Research Article3D Geometric Modeling of the Abu Madi Reservoirsand Its Implication on the Gas Development in BaltimArea (Offshore Nile Delta Egypt)
Mohamed I Abdel-Fattah1 and Ahmed Y Tawfik2
1Geology Department Faculty of Science Suez Canal University Ismailia Egypt2Geology Department Faculty of Science Suez University Suez Egypt
Correspondence should be addressed to Mohamed I Abdel-Fattah mabdelfattah99gmailcom
Received 7 July 2014 Revised 27 December 2014 Accepted 29 December 2014
Academic Editor Marek Grad
Copyright copy 2015 M I Abdel-Fattah and A Y Tawfik This is an open access article distributed under the Creative CommonsAttribution License which permits unrestricted use distribution and reproduction in any medium provided the original work isproperly cited
3D geometric modeling has received renewed attention recently in the context of visual scene understanding The reservoirgeometry of the Baltim fields is described by significant elements such as thickness depthmaps and fault planes resulting from aninterpretation based on seismic andwell data Uncertainties affect these elements throughout the entire interpretation processTheyhave some bearing on the geometric shape and subsequently on the gross reservoir volume (GRV) of the fields This uncertaintyon GRV also impacts volumes of hydrocarbons in place reserves and production profiles Thus the assessment of geometricaluncertainties is an essential first step in a field study for evaluation development and optimization purposes Seismic data arebest integrated with well and reservoir information A 3D geometric model of the Late Messinian Abu Madi reservoirs in the timeand depth domain is used to investigate the influence of the reservoir geometry on the gas entrapment Important conceptualconclusions about the reservoir system behavior are obtained using this modelThe results show that the reservoir shape influencesthe seismic response of the incised Abu Madi Paleovalley making it necessary to account for 3D effects in order to obtain accurateresults
1 Introduction
The Nile Delta Basin started to show its hydrocarbonpotential in the early 1960s Since then generations ofgeologists and geophysicists have applied different conceptsand methodologies to explore this area keeping pace withthe latest available technologies Regional gravity surveyswere followed by extended 2D seismic surveys up to almosta routine 3D acquisition in the 1990s [1] Following thistechnological and conceptual evolution the rate of technicalsuccess approached almost 100 in the last exploratory phaseof the Abu Madi Formation when 3D seismic data andseismic attributes were extensively used to predict the sanddistribution within the Abu Madi Paleovalley [1]
Baltim area lies to the north of the Nile Delta betweenlatitudes 31∘3710158402510158401015840 and 31∘5610158401910158401015840N and longitudes 31∘110158401210158401015840and 31∘261015840710158401015840E about 25 km off the Egyptian Coast It covers
an area of about 500 km2 with a length of 25 km anda width of 1875 km (Figure 1) Baltim area is considered asthe northwest extension of AbuMadi El-Qarrsquoa main channelor paleovalley [2] Inside this erosional feature the mainreservoir bodies of Abu Madi Formation are represented bysandstones mainly fluvial developed in the active channelbelts as a response to the relative fallrise of the sea level [3ndash5] Due to the discovery of hydrocarbons (gas and oil) in theonshore and offshore areas a great attention was given to theother parts of the offshore area andhigh technology of seismicdata interpretation is used which led to discovering new andbig fields at different depths ranging between 600 and 4000mand in different formations ages The area of study is a partof Nile Delta offshore area (Figure 1) which is characterizedby the presence of large number of gas fields that have abig amount of reserves from the hydrocarbon point of view[6 7]
Hindawi Publishing CorporationInternational Journal of GeophysicsVolume 2015 Article ID 369143 11 pageshttpdxdoiorg1011552015369143
2 International Journal of Geophysics
ManzalaNile Delta
0 10
32 00
Burullus
Sinai(km)
(km)
3130
Port Said
Gas field
Damietta
31 00
EL QarrsquoaAbu Madi
E DeltaKhilala
N
Mediterranean Sea
Study area
BaltimBaltim North
Baltim EastBaltim South
BE2
BE9
BE5
BE4
BN1BN2
BS
BNE1
Baltim North
Baltim East
Baltim South0 2 4 6 8 10
Abu Madi paleo-valleyGasDry
Africa
BE1
Figure 1 Location map of seismic profiles and wells in the Baltim area (offshore Nile Delta Egypt)
Baltim East was discovered in 1993 and the productionstarted in April 2000 In the past couple of years somekey workovers and a new slanted well (BE10) investigatingthe northern area of the field in addition to the goodfield performance highlighted the possibility of additionalpotential in the area and the inadequacy of the available 3Dmodel to correctly simulate the producing behavior BaltimNorth was discovered in 1995 The production started onlyin November 2005 with the tie-in of well BN1 Recentlyacquired data confirm a complex dynamic relation betweenthe Baltim East and North fields A new 3D seismic repro-cessing has been performed in 2005 merging all the 3D dataacquired on the area and producing four angle stack volumes[10]
In order to optimize the development plan in terms ofnumber and placement of wells a detailed reservoir modelcapturing the complex internal geometry of the reservoir isrequired Therefore the aim of this work is to define thegeneral geological setting of Abu Madi Formation wheregas and condensate accumulation have been trapped andto construct 3D geometric model of Abu Madi sandstonereservoirs to help in determining the next locations for thefuture development of Baltim fields
2 Geological Setting
The Upper Miocene (Messinian) Abu Madi Formation con-sists mainly of sandstone intercalated with siltstone and shaleinterbeds The Abu Madi Formation is a fluviomarine envi-ronment [3 4] The base of Abu Madi Formation is definedby an unconformity marked by iron oxide stained claysand supported by dipmeter data Based on the properties ofsandstones to siltmudstone facies the Abu Madi Formationsands could be divided into threemajor sand levels separatedby thick silty mud beds In addition a subordinate sand levelcould be identified in between levels III and II being denotedas level III A These sand levels mentioned from the older tothe younger are as follows levels III III A II and I (Figure 2)The core analysis results ditch cutting description and welllog data supported the subdivision of level III into threeunits which are mentioned from bottom to top as followslower main and upper level III units [3 4]
In Baltim area levels III upper unit III A II and I areshale-out Baltim fields in the offshore Nile Delta are gas-condensate accumulations located in the northern portionof the Abu Madi Paleovalley area [11] The fields comprisetwo separate gas pools referred to as the ldquolevel III mainrdquo
International Journal of Geophysics 3
AgeFm
LithoEnviro
La
te p
lioce
ne-h
oloc
ene
Early
-mid
dle
Kafr
El S
heik
h
Mar
ine
Fluv
iom
arin
eFl
uvio
mar
ine
Mar
ine
Late
mio
cene
M
(mes
seni
nian
)pl
ioce
ne
miocene
Emiocene Qantara
Sidi
Qawasim
Abu Madi
El-Wastani
Mit-Ghamr
Bilqas
Level II
Level III A
Upper
Mai
nLo
wer Le
vel I
II
Salem
Figure 2 Lithostratigraphic columnof theNileDelta in Baltim areaEgypt (modified after [4])
and ldquolevel III lowerrdquo within the Late Messinian Abu MadiFormation (Figure 2) Strata of the Abu Madi Formation areinterpreted to comprise two sequences [8] which are themost complex stratigraphically their deposits comprise acomplex incised valley fill (Figure 3) The lower sequence(SQ1) consists of a thick incised valley-fill of a lowstandsystems tract (LST1) overlain by a transgressive systemstract (TST1) and highstand systems tract (HST1) The uppersequence (SQ2) contains channel-fill and is interpreted as aLST2 which has thin sandstone channel deposits Above thischannel-fill sandstone and related strata with tidal influencedelineate the base of TST2 which is overlain by a HST2
The general structural setting of the Delta area has beendetermined using both geophysical methods and well dataThe main feature is the Nile Delta Hinge Zone [9] a flexurewhich affects pre-Miocene formations and extends E-Wacross the middle of the onshore Delta area producing stepfaults (Figure 4) North of theHinge Zone large normal faultsare the dominant structures These gravity-induced ldquodown-to-basinrdquo displacements occur along listric fault planes andhave thick Neogene formations which mainly developedin open marine deep-water facies The offshore Delta ischaracterized by a thick subsidence-controlled sequence oftertiary sediments South of the Hinge Zone asymmetricfolds of the Syrian Arc Fold System extend along an arcuatetrend from northern Sinai and the northern Gulf of Suezthrough the southern part of the Delta and into the WesternDesert [12] The basement in this southern area is relativelyshallow and block faulting is more common [2]
3 Materials and Methods
3D geometric model of the Abu Madi reservoirs ldquolevel IIImainrdquo and ldquolevel III lowerrdquo have been done by using Petrelprogram (Schlumbergerrsquos Reservoir Modeling Software)Theavailable data for the current study (Figure 1) are nine com-posite logs and thirty (2D) seismic profiles that were providedby the Belayim PetroleumCompany (BETROBEL) Egypt Toachieve the goal of this study the following processes andpresentations were applied to the available data well seismictie picking horizons and structural features velocity anddepth conversion and constructing time and depth contourmaps isochore maps geological model and 3D geometricmodel
31 Seismic Well Tie One of the first steps in interpretinga seismic dataset is to establish the relationship betweenseismic reflections and stratigraphy [13] Some wells havesonic (ie formation velocity) and formation density logsat least over the intervals of commercial interest from theseit is possible to construct a synthetic seismogram showingthe expected seismic response for comparison with the realseismic data In addition some wells have vertical seismicprofiling (VSP) data obtained by shooting a surface seismicsource into a downhole geophone which has the potential togive more precise tie between well and seismic data Tyingwell data (in depth) to seismic data (in time) helps to findevents (seismic reflections) that correspond to geologicalformations There are basically two methods used to tie thegeological control into the seismic data (1) using check shotdata time-depth pairs or (2) using synthetic seismogramThefirst method is the simplest but least accurate [14]
Synthetic seismograms are artificial reflection recordsmade from velocity logs by conversion of the velocity log indepth to a reflectivity function in time and by convolution ofthis function with a presumed appropriate wavelet or sourcepulse [15] Generation of the synthetic seismograms was per-formed using Petrel software In creating a synthetic seismo-gram Petrel software permits the interpreter to tie time data(seismic data) to depth data (well data) by integrating overthe velocity profile Impedance log and reflection coefficientsare generated from the velocity and density profiles Thereflection coefficients are convolved with a seismic wavelet toproduce a synthetic seismic trace The synthetic seismogramis then compared with the actual seismic traces at the drillsite The trace at the drill site was compared with adjacenttraces to assure that it was representative of that part of theseismic section Figure 5 shows a typical synthetic seismo-gram for BE1 well and illustrates the relationship betweenthe impedance logs reflection coefficients and synthetictraces for BE1 well The continuity of the sequence boundaryreflections can be observed in this figure Correlation ofthe synthetic traces with seismic sections is often helpfulin tying a well to a seismic section Generally the tiesbetween these synthetic seismograms and the seismic dataare satisfactory The main objective of synthetic seismogramis also to make time-depth relationship Any changes to thetime-depth relationship can be made and seismic horizonscan be correlated with the stratigraphic boundaries identified
4 International Journal of Geophysics
SB3
SB2
SB1
HST2
TST2
LST2
HST1
TST1
LST1
80
15
Fluvial braided channelFloodplain sediment
SQ1
SQ2
Baltim SouthBaltim EastBaltim North
Fluvial meandering channel
Sequence boundary (SB)
Abu Madi incised-valley boundary
0
Fault plane
Low
er se
quen
ce
Upp
er se
quen
ce
(km)
(m)
Figure 3 Schematic cross section illustrating the sequence stratigraphic framework of the Abu Madi Formation in Baltim fields offshoreNile Delta Egypt [8]
Mediterranean Sea
Nile Delta
N
Hinge Zone
Sinia
0 25 50
Study area
Manzala
Burullus
(km)
32∘00998400
31∘00998400
30∘00998400 30∘00998400
31∘00998400
32∘00998400
29∘30998400 30∘30998400 31∘30998400 32∘30998400
29∘30998400 30∘30998400 31∘30998400 32∘30998400
Figure 4 Hinge zone structural feature [9]
in wells When the time-depth relationship has been fine-tuned all depth indexed well tops will be automaticallyassigned the updated time value
32 Picking Horizons and Structural Features Structuralinterpretation is themost fundamental interpretation activityand includes making maps of horizons and 3D structuralmodel By correlating specific horizons on a seismic line itcan subsequently generate time data which after conversion
to depth help generate structural maps (maps which showthe geologic structure of a feature) and isochron or isopachmaps (maps which show time or thickness of particularintervals resp) [16] These maps are useful in allowingthe mapping of particular outlines and in determining thevolumes of particular reservoir hydrocarbon accumulationsBased on the well-to-seismic tie the horizons to interpretwere chosen in the seismic data The main attention wasfocused on the reservoirs intervals where four horizonswere selected to interpret The selected four horizons forinterpretation are bottom Abu Madi top level III lower toplevel III main and top Abu Madi (Figures 6 7 8 and 9)Top and bottom Abu Madi horizons have been chosen to actas structural framework to constrain the level III lower andmain reservoirs geometry
The interpreted horizons in the seismic sections frombase to top are as follows (Figures 7 to 9)
(i) Bottom Abu Madi the interpretation follows a zerocrossing value along a strongly angular unconformityat the base of the Abu Madi Fm While the acousticcontrast strongly changes along this stratigraphic sur-face the erosional geometry at its base and onlappinghorizons above allows following it (although at timeswith uncertainty) at a regional scale
(ii) Top level III lower and top level III main the inter-preted horizon is a seismic peak locally continuouswhose amplitude is related to decrease in seismic
Figure 5 Well BE1 Depth-OWT relationship with linear depth scales The impedance log reflection coefficient and synthetic seismogramgenerated using the sonic and density logs are included Part of seismic line 2609 is plotted together with the synthetic seismogram at wellBE1
0 2 4 6(km)
S NBE9 BN2 BN1
Tim
e (m
s)
1 2
34
Seismic 2D line [T6685]
BE1 BE6
minus2000
minus2500
minus3000
minus3500
minus4000 Seismic 2D line [T6101]Seismic 2D line [L1967]
BS
BNE1
BN2BE5
BE2BE1 BE4
BE3
BN1
Figure 6 Interpreted arbitrary seismic line consists of T6685 L1967 and T6101 from south to north showing the main four-horizon area((1) bottom Abu Madi (2) top level III lower (3) top level II main and (4) top Abu Madi) and the main two faults in the Baltim area
0 1 2 3(km)Ti
me (
ms)
BE9
minus2750
minus3000
minus3500
minus3250
BN2BE5
BE0
BS
BN3
(a)
0 1 2 3(km)Ti
me (
ms)
BE9
1 2
34minus2750
minus3000
minus3500
minus3250
(b)
Figure 7 Uninterpreted (a) and interpreted (b) seismic line number (L 2660) passing through Baltim East field from west to east directionwhere (1) bottom Abu Madi (2) top level III lower (3) top level II main and (4) top Abu Madi are picked
6 International Journal of GeophysicsTi
me (
ms) minus2750
minus2500
minus3000
minus3250(km)
0 1 2 3
BE1 BE4
L2609
BN2BE5BE0BS
BN3
(a)
(km)Tim
e (m
s)
BE1
1 2
34
0 1 2 3
minus2750
minus2500
minus3000
minus3250
BE4
(b)
Figure 8 Uninterpreted (a) and interpreted (b) seismic line number (L 2609) passing through Baltim East field from west to east directionwhere (1) bottom Abu Madi (2) top level III lower (3) top level II main and (4) top Abu Madi are picked
Tim
e (m
s)
BN1
BN2BE5
BE0BS
BN3
(km)0 1 2 3
minus2500
minus3000
minus3500
(a)Ti
me (
ms)
1 2
34
BN1
(km)0 1 2 3
minus2500
minus3000
minus3500
(b)
Figure 9 Uninterpreted (a) and interpreted (b) seismic line number (L 1889) passing through Baltim North field from west to east directionwhere (1) bottom Abu Madi (2) top level III lower (3) top level II main and (4) top Abu Madi are picked
velocityThe reflectionrsquos strength changes significantlyand is stronger where gas bearing sands determine astrong impedance reduction
(iii) Top Abu Madi the interpreted horizon follows azero crossing value between a strong and continuousthrough-peak couplet representing a decrease in seis-mic velocity
Because of the role faults often play in the entrapment ofhydrocarbons the techniques for finding and mapping faultshave considerable importance [15] Faults planes and theirintersections with horizons are digitized from the screendisplay in a similar way to horizons picking When a faultis picked on a seismic section its intersection will appearon an intersecting seismic section It is much easier to workwith faults on lines crossing them approximately at rightangle than on lines crossing them obliquely where the faultplane crosses the bedding at shallow angle Fault planes andtheir intersectionswith horizons are digitized from the screendisplay in a similar way to horizons picking (Figure 6)
33 Velocity and Depth Conversion Depth conversion ofa time interpretation is computationally simple and canbe quickly repeated whenever new information becomesavailable The physical quantity that relates time to depthis velocity The velocity required for converting time todepth is the P-wave velocity in the vertical direction Itcan be measured directly in a well or extracted indirectlyfrom surface seismic measurements or deduced from acombination of seismic and well measurements [17] In thepresent study the check shot survey records and sonic logswere used as a source of the velocity
The complete interpretation is automatically convertedusing Petrel software The workflow of converting databetween domains within Petrel is split into two processes
(i) make velocity model which defines how the velocityvaries in space
(ii) depth conversion which uses the velocity model tomove data between domains
4 Results and Discussion
41 Time and Depth Contour Maps The picked time valuesand the fault segments locations are posted on the base mapof the study area in order to construct structure time mapsfor the studied horizons (top Abu Madi top level III maintop level III lower and bottom AbuMadi) Then the velocitymodel is used to convert the reflection time to depths in orderto construct the structure depth maps
TopAbuMadi has two-way time (TWT) varying between2871 and 3349ms while depth values vary between 3372 and3651m (Figure 10)TheTWTof level IIImain reservoir variesbetween 2972 and 3449ms while depth values vary between3495 and 3815m (Figure 11) and achieve their maximumvalue towards the northern corner of the study area Level IIIlower reservoir has TWT varying between 3034 and 3532mswhile depth values vary between 3495 and 3943m (Figure 12)and achieve their maximum value towards the northerncorner of the study area For bottom Abu Madi the TWTvaries between 3034 and 3698ms while depth values varybetween 3495 and 4185m (Figure 13)The low-relief areas arelocated in the northern parts of the study area while the high-relief areas are located towards the south
Figure 13 Time and depth structure map of bottom Abu Madi Formation
150
150
150
BE1
BE2
BE4
BE9
BS
BN1BN2
BNE1
000
6000
12000
18000
24000
Thic
knes
s (m
)
1000
1004
1008
1012
1016
1020
1024
1028
1032
1000
1004
1008
1012
1016
1020
1024
1028
1032
times103 times103
620000 628000 636000 644000
620000 628000 636000 644000
CI = 30m
0 2 4 6 8 10(km)
N
Figure 14 Thickness map of level III main
The area was dissected by two main faults (Figure 6)the first one is a great high angle E-W normal fault dippingnorthward in the southern part of Baltim area betweenBaltimSouth andBaltimEast fieldsThe second fault between BaltimNorth and Baltim Northeast fields which are in NE-SWdirection dips to the north and displaces all the levels morethan 80mThe time and depthmaps of all horizons show thatthere is a dipping toward the north of the study area as thetime and depth values increase toward the north (Figures 10to 13)
42 Isochore Maps Two isochore thickness maps were con-structed for the two pay zones ldquolevel III lowerrdquo and ldquolevelIII mainrdquo Uncertainties affect these elements throughoutthe entire interpretation process They have some bearingon the geometric shape and subsequently on the grossreservoir volume (GRV) of the Baltim fields The increaseof the gross reservoir volume (GRV) leads subsequently to
0
0 00
0
0
0
00
0
00
0 0
150 150150
BE1
BE2
BE9
BN1BN2
BNE1
BS
6000
12000
18000
24000N
1000
1004
1008
1012
1016
1020
1024
1028
1032
times103
1000
1004
1008
1012
1016
1020
1024
1028
1032
times103
620000 628000 636000 644000
620000 628000 636000 644000
CI = 30m
0 2 4 6 8 10(km)
Thic
knes
s (m
)
minus000
0
BE4
Figure 15 Thickness map of level III lower
the increase of the net pay thickness volumes of hydrocar-bons in place reserves and production profiles For level IIImain the thickness varies between 0 and 190m (Figure 14)while for level III lower the thickness varies between 0and 210m (Figure 15) These two isochore maps show thatreservoir thickness of both level III main and lower increaseat the center of the Abu Madi Paleovalley and pinch-outand decrease toward the boundaries where the minimumthickness values were observed Thus the assessment ofgeometrical uncertainties is an essential first step in a fieldstudy for evaluation development or optimization purposes
43 Geological Model A simplified fluvial sequence strati-graphic model of the Late Messinian Abu Madi Formationis shown in Figure 16 This architecture forms the basicconceptual model of the AbuMadi reservoirs ldquolevel III mainrdquoand ldquolevel III lowerrdquo used for well correlation and seismic
Figure 16 Stratigraphic architecture of a fluvial depositional sequence influenced by base-level fluctuations for the Abu Madi incisedvalley channel system Each system tract contains a fining upward succession caused by the continuous coastal aggradation and subsequentshallowing of the fluvial graded profile List of abbreviations lowstand system tract (LST) transgressive system tract (TST) highstand systemtract (HST) maximum flooding surface (MFS) and sequence boundary (SB)
interpretation The spatial and temporal relation betweenbraided and meandering river systems is illustrated for asingle base-level cycle At the beginning of the lowstandsystem tract (LST) braided systems develop close to thesource area where the slope is generally steeper sedimentcoarser channels are overloaded and accommodation islow Towards the coastal plain as the fluvial slope becomesflatter meandering systems take over Rivers here carryless sediment are underloaded and therefore usually havesingle channels As their sinuosity increases the stresses onthe banks raise the probability of bank undermining out-of-channel flow and overbank escape of sediments Thismeandering system eventually grades into the estuary or deltafront systemsAlso due to the overall rise andflattening of thefluvial gradients the entire cycle has a fining upward tendencyBut due to the interaction between sediment supply and therate of accommodation creation at the shoreline the entiresystem progrades or retrogrades during the three stages ofbase-level rise Furthermore two sudden facies shifts may bepresent during the base-level rise cycle
As apparent from Figure 16 transgressions in fluvial sys-temsmay cause estuarine or lagoonal deposits butmore oftenthey are associated with a higher occurrence of floodplaindeposits when a marine influence remains restricted to
areas further basinwards Floodplain deposits are hardly evercontinuous over large areas due to avulsions and channelmigrations [18ndash20] Also overbank deposits and crevassesplays may hinder successful floodplain identification It istherefore often difficult and unreliable to correlate fluvialsequences based on maximum flooding surface (MFS) Thisopposed to the marine realm where the MFS is often betterdeveloped than the sequence boundary (SB) simply due tothe fact that subaerial erosion does not extend below the sealevel In fluvial settings the development of erosional surfacescan be highly heterogeneous due to incisions but theirpreservation potential is much higher due to the increasingaccommodation following the base-level lowstand This incontrast to the MFS which is trailed by a usually thinsand layer developed the highstand system tract (HST) andsubsequent base-level fall It is therefore a common practiceto correlate fluvial succession based on SBs and devise asequence stratigraphic framework in accordance with this
44 3D Geometric Modeling Reservoir modeling is playingan increasingly important role in developing and producinghydrocarbon reserves Various technologies used to under-stand a prospective reservoir provide information at manydifferent scales Core plugs are a few inches in size Well
10 International Journal of Geophysics
Elev
atio
n de
pth
(m)
BS
BE3
BE8BE9
BE5BN2BNE1
BN5BN1
BE2BE10
BE7BE4BE1
minus4100
minus4000
minus3900
minus3800
minus3700
minus3600
minus3500
minus3400
Figure 17 3D geometric model of Abu Madi reservoirs showing the promising pathway (red dashed line) of the future development wellswhich coincides with the up-to-date locations of drilling wells in the Baltim area
logs can detect properties within a few feet around thewell Seismic imaging covers a huge volume but its typicalresolution is limited to a few meters vertically and tensof meters horizontally [21] Limited by time and capitaldirect sampling of reservoir rock and fluid properties issparse Therefore geologic interpretations based on seismicinformation and understandings of sedimentary processesare used to interpolate or extrapolate the measured datain order to yield complete reservoir geometry descriptionsInformation provided by these technologies is incorporatedinto reservoir models Constructing reservoir models hasbecome a crucial step in resource development as reservoirmodeling provides a venue to integrate and reconcile allavailable data and geologic concepts [21]
One of the key challenges in reservoir modeling isaccurate representation of reservoir geometry includingthe structural framework (ie horizonsmajor depositionalsurfaces that are nearly horizontal and fault surfaces whichcan have arbitrary spatial size and orientation) and detailedstratigraphic layers (Figure 17) The structural frameworksdelineate major compartments of a reservoir and oftenprovide the first order controls on in-place fluid volumesand fluid movement during productionThus it is importantto model the structural frameworks accurately Howeverdespite decades of advances in grid generation across manydisciplines grid generation for practical reservoir modelingand simulation remains a daunting task
In typical structural modeling workflows the first taskis to build a fault network as a set of surfaces and contactsbetween these surfaces This step is itself decomposed intosurface fitting which creates one fault surface from eachfault interpretation and editing in which faults can beextended filtered and connected one to another based on
proximity and modelerrsquos interpretation Then horizons arebuilt from seismic picks conformably to the fault network[22] Fault modeling within Abu Madi reservoirs is a rea-sonably straightforward process since only two faults wereidentified during the seismic interpretation Potential synsed-imentary faults and slumps are apparent within the reservoirbut these were not modeled as they are small in scale andexhibit limited throwsThe faults are all normal displacementand were modeled using a network in which individualfault geometries were classified and their interaction definedGrid-building takes the fault model described above andconstructs a 3D grid within the framework of the reservoir-defining seismic surfaces Seismic surfaces representing topAbu Madi top level III main top level III lower andbottom Abu Madi were depth-converted as a part of theinterpretation process within Petrel software
The final result is a 3D geometric model of Abu Madireservoirs based on well and seismic data (Figure 17) andinvolves the construction of the modeling grid using aframework of seismic surfaces faults and stratigraphic wellties 3D geometric model of Abu Madi reservoirs shows thepromising pathway of the future development wells based onthe integration of seismic and well data in this study whichcoincides with the up-to-date locations of drilling wells inthe Baltim area and locates at the center of the Abu MadiPaleovalley (Figure 17)
5 Conclusions
In conclusion we have seen that the role of geometricmodeling is becoming more important for exploring reser-voir structures 3D geometric modeling provided a usefulmeans towards understanding the structure of Abu Madi
International Journal of Geophysics 11
reservoirs Baltim fields (South East and North) comprisetwo separate gas pools named ldquolevel III lowerrdquo and ldquolevelIII mainrdquo within the upper Messinian Abu Madi FormationThe trap is a structural-stratigraphic type with pinch-outagainst incised AbuMadi Paleovalley boundaries and is fault-bounded in the northern and southern part Identificationof stratigraphic architecture not only helps understand thegeological history but also has implications for hydrocarbonexploration as the confinement of flow in an incised valley hasgreat implications for channel amalgamation and producesfavorable reservoirs with potential two-way closure The AbuMadi reservoirs shape influences the seismic response ofthe incised Abu Madi Paleovalley making it necessary toaccount for 3D effects in order to obtain accurate resultsThe accuracy of the estimated thickness of each Abu Madireservoir is a critical element in assessment of reservesvolumes of hydrocarbons in place and production profilesThe promising locations of the future development wellsbased on the integration of seismic and well data coincidewith the up-to-date locations of drilling wells in the Baltimarea and locate at the center of the Abu Madi Paleovalley 3Dgeometricmodel of AbuMadi reservoir in Baltim area shouldbe kept in mind during future field development decisions
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
The authors wish to express their gratitude to Egyptian Gen-eral Petroleum Corporation (EGPC) and Belayim PetroleumCompany (PETROBEL) for providing the seismic lines welllogs and other relevant data Ministry of Higher Educationamp Scientific Research andMinistry of Petroleum in Egypt arealso acknowledged for promoting advancement in researchand establishing a possible future linkage between the indus-try and university They thank Schlumberger for furnishingthe Petrel software for the seismic interpretation
References
[1] S Dalla H Harsy andM Serazzi ldquoHydrocarbon exploration ina complex incised valley fill an example from the lateMessinianAbu Madi formation (Nile Delta Basin Egypt)rdquo The LeadingEdge vol 16 no 12 pp 1819ndash1826 1997
[2] Egyptian General Petroleum Cooperation (EGPC) Nile DeltaandNorth Sinai A Field Discoveries andHydrocarbon Potentials(A Comprehensive Overview) Egyptian General PetroleumCairo Egypt 1994
[3] M Alfy F Polo and M Shash ldquoThe geology of Abu Madigas fieldrdquo in Proceedings of the 11th Petroleum Exploration andProduction Conference pp 485ndash513 Cairo Egypt 1992
[4] I El Heiny R Rizk and M Hassan ldquoSedimentological modelfor AbuMadi sand reservoir AbuMadi field Nile Delta Egyptrdquoin Proceedings of the EGPC 10th Exploration and ProductionConference pp 1ndash38 Cairo Egypt 1990
[5] J D Pigott and M I Abdel-Fattah ldquoSeismic stratigraphy of theMessinian Nile Delta coastal plain recognition of the fluvial
Regressive Systems Tract and its potential for hydrocarbonexplorationrdquo Journal of African Earth Sciences vol 95 pp 9ndash212014
[6] R A Abu El-Ella ldquoTheNeogene-Quaternary section in theNileDelta Egypt geology and hydrocarbon potentialrdquo Journal ofPetroleum Geology vol 13 no 3 pp 329ndash340 1990
[7] J C Dolson M V Shann S Matbouly C Harwood R Rashedand H Hammouda ldquoThe petroleum potential of Egyptrdquo AAPGMemoir vol 74 pp 453ndash482 2001
[8] M I Abdel-Fattah and R M Slatt ldquoSequence stratigraphiccontrols on reservoir characterization and architecture casestudy of the Messinian Abu Madi incised-valley fill EgyptrdquoCentral European Journal of Geosciences vol 5 no 4 pp 497ndash507 2013
[9] J Harms and J Wray ldquoNile Deltardquo in Geology of Egypt R SaidEd pp 329ndash343 A A Balkema Rotterdam The Netherlands1990
[10] M H Mohamed Evaluation of hydrocarbon potentiality ofMiocene rocks in the Northern portion of Abu Madi Paleovalleyoffshore Mediterranean Sea Egypt [MS thesis] Faculty ofScience Suez Canal University 2012
[11] M I Abdel-Fattah ldquoPetrophysical characteristics of the mes-sinian abu madi formation in the baltim east and north fieldsoffshore Nile delta Egyptrdquo Journal of PetroleumGeology vol 37no 2 pp 183ndash195 2014
[12] A Rizzini F Vezzani V Cococcetta and G Milad ldquoStratigra-phy and sedimentation of a Neogene-Quaternary section in theNile Delta area (ARE)rdquo Marine Geology vol 27 no 3-4 pp327ndash348 1978
[13] M Bacon R Simm and T Redshaw 3-D Seismic InterpretationCambridge University Press New York NY USA 2003
[14] M E Badley Practical Seismic Interpretation InternationalHuman Resources Development Corporation Boston MassUSA 1985
[15] M B Dobrin and C H Savit Introduction to GeophysicalProspecting McGraw-Hill New York NY USA 4th edition1988
[16] O L Anderson and J D Pigott ldquoSeismic technology and lawpartners or adversariesrdquo Energy and Mineral Law Institute vol24 2004
[17] A R Brown Interpretation of Three-Dimensional Seismic DataAmerican Association of Petroleum Geologists and the Societyof Exploration Geophysicists 6th edition 2004
[18] O Catuneanu ldquoSequence stratigraphy of clastic systems con-cepts merits and pitfallsrdquo Journal of African Earth Sciences vol35 no 1 pp 1ndash43 2002
[19] O Catuneanu V Abreu J P Bhattacharya et al ldquoTowardsthe standardization of sequence stratigraphyrdquo Earth-ScienceReviews vol 92 pp 1ndash33 2009
[20] A M Salem J M Ketzer S Morad R R Rizk and I S Al-Aasm ldquoDiagenesis and reservoir-quality evolution of incised-valley sandstone evidence from the Abu Madi gas reservoirs(upper Miocene) the Nile Delta Basin Egyptrdquo Journal ofSedimentary Research vol 75 no 4 pp 572ndash584 2005
[21] L V Branets S S Ghai S L Lyons and X-H Wu ldquoChallengesand technologies in reservoir modelingrdquo Communications inComputational Physics vol 6 no 1 pp 1ndash23 2009
[22] G Caumon G Laurent N Cherpeau et al ldquoStructural frame-work and reservoir gridding current bottlenecks and wayforwardrdquo in Proceedings of the GUSSOWGeoscience Conferencep 8 Banff Canada 2011
Figure 1 Location map of seismic profiles and wells in the Baltim area (offshore Nile Delta Egypt)
Baltim East was discovered in 1993 and the productionstarted in April 2000 In the past couple of years somekey workovers and a new slanted well (BE10) investigatingthe northern area of the field in addition to the goodfield performance highlighted the possibility of additionalpotential in the area and the inadequacy of the available 3Dmodel to correctly simulate the producing behavior BaltimNorth was discovered in 1995 The production started onlyin November 2005 with the tie-in of well BN1 Recentlyacquired data confirm a complex dynamic relation betweenthe Baltim East and North fields A new 3D seismic repro-cessing has been performed in 2005 merging all the 3D dataacquired on the area and producing four angle stack volumes[10]
In order to optimize the development plan in terms ofnumber and placement of wells a detailed reservoir modelcapturing the complex internal geometry of the reservoir isrequired Therefore the aim of this work is to define thegeneral geological setting of Abu Madi Formation wheregas and condensate accumulation have been trapped andto construct 3D geometric model of Abu Madi sandstonereservoirs to help in determining the next locations for thefuture development of Baltim fields
2 Geological Setting
The Upper Miocene (Messinian) Abu Madi Formation con-sists mainly of sandstone intercalated with siltstone and shaleinterbeds The Abu Madi Formation is a fluviomarine envi-ronment [3 4] The base of Abu Madi Formation is definedby an unconformity marked by iron oxide stained claysand supported by dipmeter data Based on the properties ofsandstones to siltmudstone facies the Abu Madi Formationsands could be divided into threemajor sand levels separatedby thick silty mud beds In addition a subordinate sand levelcould be identified in between levels III and II being denotedas level III A These sand levels mentioned from the older tothe younger are as follows levels III III A II and I (Figure 2)The core analysis results ditch cutting description and welllog data supported the subdivision of level III into threeunits which are mentioned from bottom to top as followslower main and upper level III units [3 4]
In Baltim area levels III upper unit III A II and I areshale-out Baltim fields in the offshore Nile Delta are gas-condensate accumulations located in the northern portionof the Abu Madi Paleovalley area [11] The fields comprisetwo separate gas pools referred to as the ldquolevel III mainrdquo
International Journal of Geophysics 3
AgeFm
LithoEnviro
La
te p
lioce
ne-h
oloc
ene
Early
-mid
dle
Kafr
El S
heik
h
Mar
ine
Fluv
iom
arin
eFl
uvio
mar
ine
Mar
ine
Late
mio
cene
M
(mes
seni
nian
)pl
ioce
ne
miocene
Emiocene Qantara
Sidi
Qawasim
Abu Madi
El-Wastani
Mit-Ghamr
Bilqas
Level II
Level III A
Upper
Mai
nLo
wer Le
vel I
II
Salem
Figure 2 Lithostratigraphic columnof theNileDelta in Baltim areaEgypt (modified after [4])
and ldquolevel III lowerrdquo within the Late Messinian Abu MadiFormation (Figure 2) Strata of the Abu Madi Formation areinterpreted to comprise two sequences [8] which are themost complex stratigraphically their deposits comprise acomplex incised valley fill (Figure 3) The lower sequence(SQ1) consists of a thick incised valley-fill of a lowstandsystems tract (LST1) overlain by a transgressive systemstract (TST1) and highstand systems tract (HST1) The uppersequence (SQ2) contains channel-fill and is interpreted as aLST2 which has thin sandstone channel deposits Above thischannel-fill sandstone and related strata with tidal influencedelineate the base of TST2 which is overlain by a HST2
The general structural setting of the Delta area has beendetermined using both geophysical methods and well dataThe main feature is the Nile Delta Hinge Zone [9] a flexurewhich affects pre-Miocene formations and extends E-Wacross the middle of the onshore Delta area producing stepfaults (Figure 4) North of theHinge Zone large normal faultsare the dominant structures These gravity-induced ldquodown-to-basinrdquo displacements occur along listric fault planes andhave thick Neogene formations which mainly developedin open marine deep-water facies The offshore Delta ischaracterized by a thick subsidence-controlled sequence oftertiary sediments South of the Hinge Zone asymmetricfolds of the Syrian Arc Fold System extend along an arcuatetrend from northern Sinai and the northern Gulf of Suezthrough the southern part of the Delta and into the WesternDesert [12] The basement in this southern area is relativelyshallow and block faulting is more common [2]
3 Materials and Methods
3D geometric model of the Abu Madi reservoirs ldquolevel IIImainrdquo and ldquolevel III lowerrdquo have been done by using Petrelprogram (Schlumbergerrsquos Reservoir Modeling Software)Theavailable data for the current study (Figure 1) are nine com-posite logs and thirty (2D) seismic profiles that were providedby the Belayim PetroleumCompany (BETROBEL) Egypt Toachieve the goal of this study the following processes andpresentations were applied to the available data well seismictie picking horizons and structural features velocity anddepth conversion and constructing time and depth contourmaps isochore maps geological model and 3D geometricmodel
31 Seismic Well Tie One of the first steps in interpretinga seismic dataset is to establish the relationship betweenseismic reflections and stratigraphy [13] Some wells havesonic (ie formation velocity) and formation density logsat least over the intervals of commercial interest from theseit is possible to construct a synthetic seismogram showingthe expected seismic response for comparison with the realseismic data In addition some wells have vertical seismicprofiling (VSP) data obtained by shooting a surface seismicsource into a downhole geophone which has the potential togive more precise tie between well and seismic data Tyingwell data (in depth) to seismic data (in time) helps to findevents (seismic reflections) that correspond to geologicalformations There are basically two methods used to tie thegeological control into the seismic data (1) using check shotdata time-depth pairs or (2) using synthetic seismogramThefirst method is the simplest but least accurate [14]
Synthetic seismograms are artificial reflection recordsmade from velocity logs by conversion of the velocity log indepth to a reflectivity function in time and by convolution ofthis function with a presumed appropriate wavelet or sourcepulse [15] Generation of the synthetic seismograms was per-formed using Petrel software In creating a synthetic seismo-gram Petrel software permits the interpreter to tie time data(seismic data) to depth data (well data) by integrating overthe velocity profile Impedance log and reflection coefficientsare generated from the velocity and density profiles Thereflection coefficients are convolved with a seismic wavelet toproduce a synthetic seismic trace The synthetic seismogramis then compared with the actual seismic traces at the drillsite The trace at the drill site was compared with adjacenttraces to assure that it was representative of that part of theseismic section Figure 5 shows a typical synthetic seismo-gram for BE1 well and illustrates the relationship betweenthe impedance logs reflection coefficients and synthetictraces for BE1 well The continuity of the sequence boundaryreflections can be observed in this figure Correlation ofthe synthetic traces with seismic sections is often helpfulin tying a well to a seismic section Generally the tiesbetween these synthetic seismograms and the seismic dataare satisfactory The main objective of synthetic seismogramis also to make time-depth relationship Any changes to thetime-depth relationship can be made and seismic horizonscan be correlated with the stratigraphic boundaries identified
4 International Journal of Geophysics
SB3
SB2
SB1
HST2
TST2
LST2
HST1
TST1
LST1
80
15
Fluvial braided channelFloodplain sediment
SQ1
SQ2
Baltim SouthBaltim EastBaltim North
Fluvial meandering channel
Sequence boundary (SB)
Abu Madi incised-valley boundary
0
Fault plane
Low
er se
quen
ce
Upp
er se
quen
ce
(km)
(m)
Figure 3 Schematic cross section illustrating the sequence stratigraphic framework of the Abu Madi Formation in Baltim fields offshoreNile Delta Egypt [8]
Mediterranean Sea
Nile Delta
N
Hinge Zone
Sinia
0 25 50
Study area
Manzala
Burullus
(km)
32∘00998400
31∘00998400
30∘00998400 30∘00998400
31∘00998400
32∘00998400
29∘30998400 30∘30998400 31∘30998400 32∘30998400
29∘30998400 30∘30998400 31∘30998400 32∘30998400
Figure 4 Hinge zone structural feature [9]
in wells When the time-depth relationship has been fine-tuned all depth indexed well tops will be automaticallyassigned the updated time value
32 Picking Horizons and Structural Features Structuralinterpretation is themost fundamental interpretation activityand includes making maps of horizons and 3D structuralmodel By correlating specific horizons on a seismic line itcan subsequently generate time data which after conversion
to depth help generate structural maps (maps which showthe geologic structure of a feature) and isochron or isopachmaps (maps which show time or thickness of particularintervals resp) [16] These maps are useful in allowingthe mapping of particular outlines and in determining thevolumes of particular reservoir hydrocarbon accumulationsBased on the well-to-seismic tie the horizons to interpretwere chosen in the seismic data The main attention wasfocused on the reservoirs intervals where four horizonswere selected to interpret The selected four horizons forinterpretation are bottom Abu Madi top level III lower toplevel III main and top Abu Madi (Figures 6 7 8 and 9)Top and bottom Abu Madi horizons have been chosen to actas structural framework to constrain the level III lower andmain reservoirs geometry
The interpreted horizons in the seismic sections frombase to top are as follows (Figures 7 to 9)
(i) Bottom Abu Madi the interpretation follows a zerocrossing value along a strongly angular unconformityat the base of the Abu Madi Fm While the acousticcontrast strongly changes along this stratigraphic sur-face the erosional geometry at its base and onlappinghorizons above allows following it (although at timeswith uncertainty) at a regional scale
(ii) Top level III lower and top level III main the inter-preted horizon is a seismic peak locally continuouswhose amplitude is related to decrease in seismic
Figure 5 Well BE1 Depth-OWT relationship with linear depth scales The impedance log reflection coefficient and synthetic seismogramgenerated using the sonic and density logs are included Part of seismic line 2609 is plotted together with the synthetic seismogram at wellBE1
0 2 4 6(km)
S NBE9 BN2 BN1
Tim
e (m
s)
1 2
34
Seismic 2D line [T6685]
BE1 BE6
minus2000
minus2500
minus3000
minus3500
minus4000 Seismic 2D line [T6101]Seismic 2D line [L1967]
BS
BNE1
BN2BE5
BE2BE1 BE4
BE3
BN1
Figure 6 Interpreted arbitrary seismic line consists of T6685 L1967 and T6101 from south to north showing the main four-horizon area((1) bottom Abu Madi (2) top level III lower (3) top level II main and (4) top Abu Madi) and the main two faults in the Baltim area
0 1 2 3(km)Ti
me (
ms)
BE9
minus2750
minus3000
minus3500
minus3250
BN2BE5
BE0
BS
BN3
(a)
0 1 2 3(km)Ti
me (
ms)
BE9
1 2
34minus2750
minus3000
minus3500
minus3250
(b)
Figure 7 Uninterpreted (a) and interpreted (b) seismic line number (L 2660) passing through Baltim East field from west to east directionwhere (1) bottom Abu Madi (2) top level III lower (3) top level II main and (4) top Abu Madi are picked
6 International Journal of GeophysicsTi
me (
ms) minus2750
minus2500
minus3000
minus3250(km)
0 1 2 3
BE1 BE4
L2609
BN2BE5BE0BS
BN3
(a)
(km)Tim
e (m
s)
BE1
1 2
34
0 1 2 3
minus2750
minus2500
minus3000
minus3250
BE4
(b)
Figure 8 Uninterpreted (a) and interpreted (b) seismic line number (L 2609) passing through Baltim East field from west to east directionwhere (1) bottom Abu Madi (2) top level III lower (3) top level II main and (4) top Abu Madi are picked
Tim
e (m
s)
BN1
BN2BE5
BE0BS
BN3
(km)0 1 2 3
minus2500
minus3000
minus3500
(a)Ti
me (
ms)
1 2
34
BN1
(km)0 1 2 3
minus2500
minus3000
minus3500
(b)
Figure 9 Uninterpreted (a) and interpreted (b) seismic line number (L 1889) passing through Baltim North field from west to east directionwhere (1) bottom Abu Madi (2) top level III lower (3) top level II main and (4) top Abu Madi are picked
velocityThe reflectionrsquos strength changes significantlyand is stronger where gas bearing sands determine astrong impedance reduction
(iii) Top Abu Madi the interpreted horizon follows azero crossing value between a strong and continuousthrough-peak couplet representing a decrease in seis-mic velocity
Because of the role faults often play in the entrapment ofhydrocarbons the techniques for finding and mapping faultshave considerable importance [15] Faults planes and theirintersections with horizons are digitized from the screendisplay in a similar way to horizons picking When a faultis picked on a seismic section its intersection will appearon an intersecting seismic section It is much easier to workwith faults on lines crossing them approximately at rightangle than on lines crossing them obliquely where the faultplane crosses the bedding at shallow angle Fault planes andtheir intersectionswith horizons are digitized from the screendisplay in a similar way to horizons picking (Figure 6)
33 Velocity and Depth Conversion Depth conversion ofa time interpretation is computationally simple and canbe quickly repeated whenever new information becomesavailable The physical quantity that relates time to depthis velocity The velocity required for converting time todepth is the P-wave velocity in the vertical direction Itcan be measured directly in a well or extracted indirectlyfrom surface seismic measurements or deduced from acombination of seismic and well measurements [17] In thepresent study the check shot survey records and sonic logswere used as a source of the velocity
The complete interpretation is automatically convertedusing Petrel software The workflow of converting databetween domains within Petrel is split into two processes
(i) make velocity model which defines how the velocityvaries in space
(ii) depth conversion which uses the velocity model tomove data between domains
4 Results and Discussion
41 Time and Depth Contour Maps The picked time valuesand the fault segments locations are posted on the base mapof the study area in order to construct structure time mapsfor the studied horizons (top Abu Madi top level III maintop level III lower and bottom AbuMadi) Then the velocitymodel is used to convert the reflection time to depths in orderto construct the structure depth maps
TopAbuMadi has two-way time (TWT) varying between2871 and 3349ms while depth values vary between 3372 and3651m (Figure 10)TheTWTof level IIImain reservoir variesbetween 2972 and 3449ms while depth values vary between3495 and 3815m (Figure 11) and achieve their maximumvalue towards the northern corner of the study area Level IIIlower reservoir has TWT varying between 3034 and 3532mswhile depth values vary between 3495 and 3943m (Figure 12)and achieve their maximum value towards the northerncorner of the study area For bottom Abu Madi the TWTvaries between 3034 and 3698ms while depth values varybetween 3495 and 4185m (Figure 13)The low-relief areas arelocated in the northern parts of the study area while the high-relief areas are located towards the south
Figure 13 Time and depth structure map of bottom Abu Madi Formation
150
150
150
BE1
BE2
BE4
BE9
BS
BN1BN2
BNE1
000
6000
12000
18000
24000
Thic
knes
s (m
)
1000
1004
1008
1012
1016
1020
1024
1028
1032
1000
1004
1008
1012
1016
1020
1024
1028
1032
times103 times103
620000 628000 636000 644000
620000 628000 636000 644000
CI = 30m
0 2 4 6 8 10(km)
N
Figure 14 Thickness map of level III main
The area was dissected by two main faults (Figure 6)the first one is a great high angle E-W normal fault dippingnorthward in the southern part of Baltim area betweenBaltimSouth andBaltimEast fieldsThe second fault between BaltimNorth and Baltim Northeast fields which are in NE-SWdirection dips to the north and displaces all the levels morethan 80mThe time and depthmaps of all horizons show thatthere is a dipping toward the north of the study area as thetime and depth values increase toward the north (Figures 10to 13)
42 Isochore Maps Two isochore thickness maps were con-structed for the two pay zones ldquolevel III lowerrdquo and ldquolevelIII mainrdquo Uncertainties affect these elements throughoutthe entire interpretation process They have some bearingon the geometric shape and subsequently on the grossreservoir volume (GRV) of the Baltim fields The increaseof the gross reservoir volume (GRV) leads subsequently to
0
0 00
0
0
0
00
0
00
0 0
150 150150
BE1
BE2
BE9
BN1BN2
BNE1
BS
6000
12000
18000
24000N
1000
1004
1008
1012
1016
1020
1024
1028
1032
times103
1000
1004
1008
1012
1016
1020
1024
1028
1032
times103
620000 628000 636000 644000
620000 628000 636000 644000
CI = 30m
0 2 4 6 8 10(km)
Thic
knes
s (m
)
minus000
0
BE4
Figure 15 Thickness map of level III lower
the increase of the net pay thickness volumes of hydrocar-bons in place reserves and production profiles For level IIImain the thickness varies between 0 and 190m (Figure 14)while for level III lower the thickness varies between 0and 210m (Figure 15) These two isochore maps show thatreservoir thickness of both level III main and lower increaseat the center of the Abu Madi Paleovalley and pinch-outand decrease toward the boundaries where the minimumthickness values were observed Thus the assessment ofgeometrical uncertainties is an essential first step in a fieldstudy for evaluation development or optimization purposes
43 Geological Model A simplified fluvial sequence strati-graphic model of the Late Messinian Abu Madi Formationis shown in Figure 16 This architecture forms the basicconceptual model of the AbuMadi reservoirs ldquolevel III mainrdquoand ldquolevel III lowerrdquo used for well correlation and seismic
Figure 16 Stratigraphic architecture of a fluvial depositional sequence influenced by base-level fluctuations for the Abu Madi incisedvalley channel system Each system tract contains a fining upward succession caused by the continuous coastal aggradation and subsequentshallowing of the fluvial graded profile List of abbreviations lowstand system tract (LST) transgressive system tract (TST) highstand systemtract (HST) maximum flooding surface (MFS) and sequence boundary (SB)
interpretation The spatial and temporal relation betweenbraided and meandering river systems is illustrated for asingle base-level cycle At the beginning of the lowstandsystem tract (LST) braided systems develop close to thesource area where the slope is generally steeper sedimentcoarser channels are overloaded and accommodation islow Towards the coastal plain as the fluvial slope becomesflatter meandering systems take over Rivers here carryless sediment are underloaded and therefore usually havesingle channels As their sinuosity increases the stresses onthe banks raise the probability of bank undermining out-of-channel flow and overbank escape of sediments Thismeandering system eventually grades into the estuary or deltafront systemsAlso due to the overall rise andflattening of thefluvial gradients the entire cycle has a fining upward tendencyBut due to the interaction between sediment supply and therate of accommodation creation at the shoreline the entiresystem progrades or retrogrades during the three stages ofbase-level rise Furthermore two sudden facies shifts may bepresent during the base-level rise cycle
As apparent from Figure 16 transgressions in fluvial sys-temsmay cause estuarine or lagoonal deposits butmore oftenthey are associated with a higher occurrence of floodplaindeposits when a marine influence remains restricted to
areas further basinwards Floodplain deposits are hardly evercontinuous over large areas due to avulsions and channelmigrations [18ndash20] Also overbank deposits and crevassesplays may hinder successful floodplain identification It istherefore often difficult and unreliable to correlate fluvialsequences based on maximum flooding surface (MFS) Thisopposed to the marine realm where the MFS is often betterdeveloped than the sequence boundary (SB) simply due tothe fact that subaerial erosion does not extend below the sealevel In fluvial settings the development of erosional surfacescan be highly heterogeneous due to incisions but theirpreservation potential is much higher due to the increasingaccommodation following the base-level lowstand This incontrast to the MFS which is trailed by a usually thinsand layer developed the highstand system tract (HST) andsubsequent base-level fall It is therefore a common practiceto correlate fluvial succession based on SBs and devise asequence stratigraphic framework in accordance with this
44 3D Geometric Modeling Reservoir modeling is playingan increasingly important role in developing and producinghydrocarbon reserves Various technologies used to under-stand a prospective reservoir provide information at manydifferent scales Core plugs are a few inches in size Well
10 International Journal of Geophysics
Elev
atio
n de
pth
(m)
BS
BE3
BE8BE9
BE5BN2BNE1
BN5BN1
BE2BE10
BE7BE4BE1
minus4100
minus4000
minus3900
minus3800
minus3700
minus3600
minus3500
minus3400
Figure 17 3D geometric model of Abu Madi reservoirs showing the promising pathway (red dashed line) of the future development wellswhich coincides with the up-to-date locations of drilling wells in the Baltim area
logs can detect properties within a few feet around thewell Seismic imaging covers a huge volume but its typicalresolution is limited to a few meters vertically and tensof meters horizontally [21] Limited by time and capitaldirect sampling of reservoir rock and fluid properties issparse Therefore geologic interpretations based on seismicinformation and understandings of sedimentary processesare used to interpolate or extrapolate the measured datain order to yield complete reservoir geometry descriptionsInformation provided by these technologies is incorporatedinto reservoir models Constructing reservoir models hasbecome a crucial step in resource development as reservoirmodeling provides a venue to integrate and reconcile allavailable data and geologic concepts [21]
One of the key challenges in reservoir modeling isaccurate representation of reservoir geometry includingthe structural framework (ie horizonsmajor depositionalsurfaces that are nearly horizontal and fault surfaces whichcan have arbitrary spatial size and orientation) and detailedstratigraphic layers (Figure 17) The structural frameworksdelineate major compartments of a reservoir and oftenprovide the first order controls on in-place fluid volumesand fluid movement during productionThus it is importantto model the structural frameworks accurately Howeverdespite decades of advances in grid generation across manydisciplines grid generation for practical reservoir modelingand simulation remains a daunting task
In typical structural modeling workflows the first taskis to build a fault network as a set of surfaces and contactsbetween these surfaces This step is itself decomposed intosurface fitting which creates one fault surface from eachfault interpretation and editing in which faults can beextended filtered and connected one to another based on
proximity and modelerrsquos interpretation Then horizons arebuilt from seismic picks conformably to the fault network[22] Fault modeling within Abu Madi reservoirs is a rea-sonably straightforward process since only two faults wereidentified during the seismic interpretation Potential synsed-imentary faults and slumps are apparent within the reservoirbut these were not modeled as they are small in scale andexhibit limited throwsThe faults are all normal displacementand were modeled using a network in which individualfault geometries were classified and their interaction definedGrid-building takes the fault model described above andconstructs a 3D grid within the framework of the reservoir-defining seismic surfaces Seismic surfaces representing topAbu Madi top level III main top level III lower andbottom Abu Madi were depth-converted as a part of theinterpretation process within Petrel software
The final result is a 3D geometric model of Abu Madireservoirs based on well and seismic data (Figure 17) andinvolves the construction of the modeling grid using aframework of seismic surfaces faults and stratigraphic wellties 3D geometric model of Abu Madi reservoirs shows thepromising pathway of the future development wells based onthe integration of seismic and well data in this study whichcoincides with the up-to-date locations of drilling wells inthe Baltim area and locates at the center of the Abu MadiPaleovalley (Figure 17)
5 Conclusions
In conclusion we have seen that the role of geometricmodeling is becoming more important for exploring reser-voir structures 3D geometric modeling provided a usefulmeans towards understanding the structure of Abu Madi
International Journal of Geophysics 11
reservoirs Baltim fields (South East and North) comprisetwo separate gas pools named ldquolevel III lowerrdquo and ldquolevelIII mainrdquo within the upper Messinian Abu Madi FormationThe trap is a structural-stratigraphic type with pinch-outagainst incised AbuMadi Paleovalley boundaries and is fault-bounded in the northern and southern part Identificationof stratigraphic architecture not only helps understand thegeological history but also has implications for hydrocarbonexploration as the confinement of flow in an incised valley hasgreat implications for channel amalgamation and producesfavorable reservoirs with potential two-way closure The AbuMadi reservoirs shape influences the seismic response ofthe incised Abu Madi Paleovalley making it necessary toaccount for 3D effects in order to obtain accurate resultsThe accuracy of the estimated thickness of each Abu Madireservoir is a critical element in assessment of reservesvolumes of hydrocarbons in place and production profilesThe promising locations of the future development wellsbased on the integration of seismic and well data coincidewith the up-to-date locations of drilling wells in the Baltimarea and locate at the center of the Abu Madi Paleovalley 3Dgeometricmodel of AbuMadi reservoir in Baltim area shouldbe kept in mind during future field development decisions
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
The authors wish to express their gratitude to Egyptian Gen-eral Petroleum Corporation (EGPC) and Belayim PetroleumCompany (PETROBEL) for providing the seismic lines welllogs and other relevant data Ministry of Higher Educationamp Scientific Research andMinistry of Petroleum in Egypt arealso acknowledged for promoting advancement in researchand establishing a possible future linkage between the indus-try and university They thank Schlumberger for furnishingthe Petrel software for the seismic interpretation
References
[1] S Dalla H Harsy andM Serazzi ldquoHydrocarbon exploration ina complex incised valley fill an example from the lateMessinianAbu Madi formation (Nile Delta Basin Egypt)rdquo The LeadingEdge vol 16 no 12 pp 1819ndash1826 1997
[2] Egyptian General Petroleum Cooperation (EGPC) Nile DeltaandNorth Sinai A Field Discoveries andHydrocarbon Potentials(A Comprehensive Overview) Egyptian General PetroleumCairo Egypt 1994
[3] M Alfy F Polo and M Shash ldquoThe geology of Abu Madigas fieldrdquo in Proceedings of the 11th Petroleum Exploration andProduction Conference pp 485ndash513 Cairo Egypt 1992
[4] I El Heiny R Rizk and M Hassan ldquoSedimentological modelfor AbuMadi sand reservoir AbuMadi field Nile Delta Egyptrdquoin Proceedings of the EGPC 10th Exploration and ProductionConference pp 1ndash38 Cairo Egypt 1990
[5] J D Pigott and M I Abdel-Fattah ldquoSeismic stratigraphy of theMessinian Nile Delta coastal plain recognition of the fluvial
Regressive Systems Tract and its potential for hydrocarbonexplorationrdquo Journal of African Earth Sciences vol 95 pp 9ndash212014
[6] R A Abu El-Ella ldquoTheNeogene-Quaternary section in theNileDelta Egypt geology and hydrocarbon potentialrdquo Journal ofPetroleum Geology vol 13 no 3 pp 329ndash340 1990
[7] J C Dolson M V Shann S Matbouly C Harwood R Rashedand H Hammouda ldquoThe petroleum potential of Egyptrdquo AAPGMemoir vol 74 pp 453ndash482 2001
[8] M I Abdel-Fattah and R M Slatt ldquoSequence stratigraphiccontrols on reservoir characterization and architecture casestudy of the Messinian Abu Madi incised-valley fill EgyptrdquoCentral European Journal of Geosciences vol 5 no 4 pp 497ndash507 2013
[9] J Harms and J Wray ldquoNile Deltardquo in Geology of Egypt R SaidEd pp 329ndash343 A A Balkema Rotterdam The Netherlands1990
[10] M H Mohamed Evaluation of hydrocarbon potentiality ofMiocene rocks in the Northern portion of Abu Madi Paleovalleyoffshore Mediterranean Sea Egypt [MS thesis] Faculty ofScience Suez Canal University 2012
[11] M I Abdel-Fattah ldquoPetrophysical characteristics of the mes-sinian abu madi formation in the baltim east and north fieldsoffshore Nile delta Egyptrdquo Journal of PetroleumGeology vol 37no 2 pp 183ndash195 2014
[12] A Rizzini F Vezzani V Cococcetta and G Milad ldquoStratigra-phy and sedimentation of a Neogene-Quaternary section in theNile Delta area (ARE)rdquo Marine Geology vol 27 no 3-4 pp327ndash348 1978
[13] M Bacon R Simm and T Redshaw 3-D Seismic InterpretationCambridge University Press New York NY USA 2003
[14] M E Badley Practical Seismic Interpretation InternationalHuman Resources Development Corporation Boston MassUSA 1985
[15] M B Dobrin and C H Savit Introduction to GeophysicalProspecting McGraw-Hill New York NY USA 4th edition1988
[16] O L Anderson and J D Pigott ldquoSeismic technology and lawpartners or adversariesrdquo Energy and Mineral Law Institute vol24 2004
[17] A R Brown Interpretation of Three-Dimensional Seismic DataAmerican Association of Petroleum Geologists and the Societyof Exploration Geophysicists 6th edition 2004
[18] O Catuneanu ldquoSequence stratigraphy of clastic systems con-cepts merits and pitfallsrdquo Journal of African Earth Sciences vol35 no 1 pp 1ndash43 2002
[19] O Catuneanu V Abreu J P Bhattacharya et al ldquoTowardsthe standardization of sequence stratigraphyrdquo Earth-ScienceReviews vol 92 pp 1ndash33 2009
[20] A M Salem J M Ketzer S Morad R R Rizk and I S Al-Aasm ldquoDiagenesis and reservoir-quality evolution of incised-valley sandstone evidence from the Abu Madi gas reservoirs(upper Miocene) the Nile Delta Basin Egyptrdquo Journal ofSedimentary Research vol 75 no 4 pp 572ndash584 2005
[21] L V Branets S S Ghai S L Lyons and X-H Wu ldquoChallengesand technologies in reservoir modelingrdquo Communications inComputational Physics vol 6 no 1 pp 1ndash23 2009
[22] G Caumon G Laurent N Cherpeau et al ldquoStructural frame-work and reservoir gridding current bottlenecks and wayforwardrdquo in Proceedings of the GUSSOWGeoscience Conferencep 8 Banff Canada 2011
Figure 2 Lithostratigraphic columnof theNileDelta in Baltim areaEgypt (modified after [4])
and ldquolevel III lowerrdquo within the Late Messinian Abu MadiFormation (Figure 2) Strata of the Abu Madi Formation areinterpreted to comprise two sequences [8] which are themost complex stratigraphically their deposits comprise acomplex incised valley fill (Figure 3) The lower sequence(SQ1) consists of a thick incised valley-fill of a lowstandsystems tract (LST1) overlain by a transgressive systemstract (TST1) and highstand systems tract (HST1) The uppersequence (SQ2) contains channel-fill and is interpreted as aLST2 which has thin sandstone channel deposits Above thischannel-fill sandstone and related strata with tidal influencedelineate the base of TST2 which is overlain by a HST2
The general structural setting of the Delta area has beendetermined using both geophysical methods and well dataThe main feature is the Nile Delta Hinge Zone [9] a flexurewhich affects pre-Miocene formations and extends E-Wacross the middle of the onshore Delta area producing stepfaults (Figure 4) North of theHinge Zone large normal faultsare the dominant structures These gravity-induced ldquodown-to-basinrdquo displacements occur along listric fault planes andhave thick Neogene formations which mainly developedin open marine deep-water facies The offshore Delta ischaracterized by a thick subsidence-controlled sequence oftertiary sediments South of the Hinge Zone asymmetricfolds of the Syrian Arc Fold System extend along an arcuatetrend from northern Sinai and the northern Gulf of Suezthrough the southern part of the Delta and into the WesternDesert [12] The basement in this southern area is relativelyshallow and block faulting is more common [2]
3 Materials and Methods
3D geometric model of the Abu Madi reservoirs ldquolevel IIImainrdquo and ldquolevel III lowerrdquo have been done by using Petrelprogram (Schlumbergerrsquos Reservoir Modeling Software)Theavailable data for the current study (Figure 1) are nine com-posite logs and thirty (2D) seismic profiles that were providedby the Belayim PetroleumCompany (BETROBEL) Egypt Toachieve the goal of this study the following processes andpresentations were applied to the available data well seismictie picking horizons and structural features velocity anddepth conversion and constructing time and depth contourmaps isochore maps geological model and 3D geometricmodel
31 Seismic Well Tie One of the first steps in interpretinga seismic dataset is to establish the relationship betweenseismic reflections and stratigraphy [13] Some wells havesonic (ie formation velocity) and formation density logsat least over the intervals of commercial interest from theseit is possible to construct a synthetic seismogram showingthe expected seismic response for comparison with the realseismic data In addition some wells have vertical seismicprofiling (VSP) data obtained by shooting a surface seismicsource into a downhole geophone which has the potential togive more precise tie between well and seismic data Tyingwell data (in depth) to seismic data (in time) helps to findevents (seismic reflections) that correspond to geologicalformations There are basically two methods used to tie thegeological control into the seismic data (1) using check shotdata time-depth pairs or (2) using synthetic seismogramThefirst method is the simplest but least accurate [14]
Synthetic seismograms are artificial reflection recordsmade from velocity logs by conversion of the velocity log indepth to a reflectivity function in time and by convolution ofthis function with a presumed appropriate wavelet or sourcepulse [15] Generation of the synthetic seismograms was per-formed using Petrel software In creating a synthetic seismo-gram Petrel software permits the interpreter to tie time data(seismic data) to depth data (well data) by integrating overthe velocity profile Impedance log and reflection coefficientsare generated from the velocity and density profiles Thereflection coefficients are convolved with a seismic wavelet toproduce a synthetic seismic trace The synthetic seismogramis then compared with the actual seismic traces at the drillsite The trace at the drill site was compared with adjacenttraces to assure that it was representative of that part of theseismic section Figure 5 shows a typical synthetic seismo-gram for BE1 well and illustrates the relationship betweenthe impedance logs reflection coefficients and synthetictraces for BE1 well The continuity of the sequence boundaryreflections can be observed in this figure Correlation ofthe synthetic traces with seismic sections is often helpfulin tying a well to a seismic section Generally the tiesbetween these synthetic seismograms and the seismic dataare satisfactory The main objective of synthetic seismogramis also to make time-depth relationship Any changes to thetime-depth relationship can be made and seismic horizonscan be correlated with the stratigraphic boundaries identified
4 International Journal of Geophysics
SB3
SB2
SB1
HST2
TST2
LST2
HST1
TST1
LST1
80
15
Fluvial braided channelFloodplain sediment
SQ1
SQ2
Baltim SouthBaltim EastBaltim North
Fluvial meandering channel
Sequence boundary (SB)
Abu Madi incised-valley boundary
0
Fault plane
Low
er se
quen
ce
Upp
er se
quen
ce
(km)
(m)
Figure 3 Schematic cross section illustrating the sequence stratigraphic framework of the Abu Madi Formation in Baltim fields offshoreNile Delta Egypt [8]
Mediterranean Sea
Nile Delta
N
Hinge Zone
Sinia
0 25 50
Study area
Manzala
Burullus
(km)
32∘00998400
31∘00998400
30∘00998400 30∘00998400
31∘00998400
32∘00998400
29∘30998400 30∘30998400 31∘30998400 32∘30998400
29∘30998400 30∘30998400 31∘30998400 32∘30998400
Figure 4 Hinge zone structural feature [9]
in wells When the time-depth relationship has been fine-tuned all depth indexed well tops will be automaticallyassigned the updated time value
32 Picking Horizons and Structural Features Structuralinterpretation is themost fundamental interpretation activityand includes making maps of horizons and 3D structuralmodel By correlating specific horizons on a seismic line itcan subsequently generate time data which after conversion
to depth help generate structural maps (maps which showthe geologic structure of a feature) and isochron or isopachmaps (maps which show time or thickness of particularintervals resp) [16] These maps are useful in allowingthe mapping of particular outlines and in determining thevolumes of particular reservoir hydrocarbon accumulationsBased on the well-to-seismic tie the horizons to interpretwere chosen in the seismic data The main attention wasfocused on the reservoirs intervals where four horizonswere selected to interpret The selected four horizons forinterpretation are bottom Abu Madi top level III lower toplevel III main and top Abu Madi (Figures 6 7 8 and 9)Top and bottom Abu Madi horizons have been chosen to actas structural framework to constrain the level III lower andmain reservoirs geometry
The interpreted horizons in the seismic sections frombase to top are as follows (Figures 7 to 9)
(i) Bottom Abu Madi the interpretation follows a zerocrossing value along a strongly angular unconformityat the base of the Abu Madi Fm While the acousticcontrast strongly changes along this stratigraphic sur-face the erosional geometry at its base and onlappinghorizons above allows following it (although at timeswith uncertainty) at a regional scale
(ii) Top level III lower and top level III main the inter-preted horizon is a seismic peak locally continuouswhose amplitude is related to decrease in seismic
Figure 5 Well BE1 Depth-OWT relationship with linear depth scales The impedance log reflection coefficient and synthetic seismogramgenerated using the sonic and density logs are included Part of seismic line 2609 is plotted together with the synthetic seismogram at wellBE1
0 2 4 6(km)
S NBE9 BN2 BN1
Tim
e (m
s)
1 2
34
Seismic 2D line [T6685]
BE1 BE6
minus2000
minus2500
minus3000
minus3500
minus4000 Seismic 2D line [T6101]Seismic 2D line [L1967]
BS
BNE1
BN2BE5
BE2BE1 BE4
BE3
BN1
Figure 6 Interpreted arbitrary seismic line consists of T6685 L1967 and T6101 from south to north showing the main four-horizon area((1) bottom Abu Madi (2) top level III lower (3) top level II main and (4) top Abu Madi) and the main two faults in the Baltim area
0 1 2 3(km)Ti
me (
ms)
BE9
minus2750
minus3000
minus3500
minus3250
BN2BE5
BE0
BS
BN3
(a)
0 1 2 3(km)Ti
me (
ms)
BE9
1 2
34minus2750
minus3000
minus3500
minus3250
(b)
Figure 7 Uninterpreted (a) and interpreted (b) seismic line number (L 2660) passing through Baltim East field from west to east directionwhere (1) bottom Abu Madi (2) top level III lower (3) top level II main and (4) top Abu Madi are picked
6 International Journal of GeophysicsTi
me (
ms) minus2750
minus2500
minus3000
minus3250(km)
0 1 2 3
BE1 BE4
L2609
BN2BE5BE0BS
BN3
(a)
(km)Tim
e (m
s)
BE1
1 2
34
0 1 2 3
minus2750
minus2500
minus3000
minus3250
BE4
(b)
Figure 8 Uninterpreted (a) and interpreted (b) seismic line number (L 2609) passing through Baltim East field from west to east directionwhere (1) bottom Abu Madi (2) top level III lower (3) top level II main and (4) top Abu Madi are picked
Tim
e (m
s)
BN1
BN2BE5
BE0BS
BN3
(km)0 1 2 3
minus2500
minus3000
minus3500
(a)Ti
me (
ms)
1 2
34
BN1
(km)0 1 2 3
minus2500
minus3000
minus3500
(b)
Figure 9 Uninterpreted (a) and interpreted (b) seismic line number (L 1889) passing through Baltim North field from west to east directionwhere (1) bottom Abu Madi (2) top level III lower (3) top level II main and (4) top Abu Madi are picked
velocityThe reflectionrsquos strength changes significantlyand is stronger where gas bearing sands determine astrong impedance reduction
(iii) Top Abu Madi the interpreted horizon follows azero crossing value between a strong and continuousthrough-peak couplet representing a decrease in seis-mic velocity
Because of the role faults often play in the entrapment ofhydrocarbons the techniques for finding and mapping faultshave considerable importance [15] Faults planes and theirintersections with horizons are digitized from the screendisplay in a similar way to horizons picking When a faultis picked on a seismic section its intersection will appearon an intersecting seismic section It is much easier to workwith faults on lines crossing them approximately at rightangle than on lines crossing them obliquely where the faultplane crosses the bedding at shallow angle Fault planes andtheir intersectionswith horizons are digitized from the screendisplay in a similar way to horizons picking (Figure 6)
33 Velocity and Depth Conversion Depth conversion ofa time interpretation is computationally simple and canbe quickly repeated whenever new information becomesavailable The physical quantity that relates time to depthis velocity The velocity required for converting time todepth is the P-wave velocity in the vertical direction Itcan be measured directly in a well or extracted indirectlyfrom surface seismic measurements or deduced from acombination of seismic and well measurements [17] In thepresent study the check shot survey records and sonic logswere used as a source of the velocity
The complete interpretation is automatically convertedusing Petrel software The workflow of converting databetween domains within Petrel is split into two processes
(i) make velocity model which defines how the velocityvaries in space
(ii) depth conversion which uses the velocity model tomove data between domains
4 Results and Discussion
41 Time and Depth Contour Maps The picked time valuesand the fault segments locations are posted on the base mapof the study area in order to construct structure time mapsfor the studied horizons (top Abu Madi top level III maintop level III lower and bottom AbuMadi) Then the velocitymodel is used to convert the reflection time to depths in orderto construct the structure depth maps
TopAbuMadi has two-way time (TWT) varying between2871 and 3349ms while depth values vary between 3372 and3651m (Figure 10)TheTWTof level IIImain reservoir variesbetween 2972 and 3449ms while depth values vary between3495 and 3815m (Figure 11) and achieve their maximumvalue towards the northern corner of the study area Level IIIlower reservoir has TWT varying between 3034 and 3532mswhile depth values vary between 3495 and 3943m (Figure 12)and achieve their maximum value towards the northerncorner of the study area For bottom Abu Madi the TWTvaries between 3034 and 3698ms while depth values varybetween 3495 and 4185m (Figure 13)The low-relief areas arelocated in the northern parts of the study area while the high-relief areas are located towards the south
Figure 13 Time and depth structure map of bottom Abu Madi Formation
150
150
150
BE1
BE2
BE4
BE9
BS
BN1BN2
BNE1
000
6000
12000
18000
24000
Thic
knes
s (m
)
1000
1004
1008
1012
1016
1020
1024
1028
1032
1000
1004
1008
1012
1016
1020
1024
1028
1032
times103 times103
620000 628000 636000 644000
620000 628000 636000 644000
CI = 30m
0 2 4 6 8 10(km)
N
Figure 14 Thickness map of level III main
The area was dissected by two main faults (Figure 6)the first one is a great high angle E-W normal fault dippingnorthward in the southern part of Baltim area betweenBaltimSouth andBaltimEast fieldsThe second fault between BaltimNorth and Baltim Northeast fields which are in NE-SWdirection dips to the north and displaces all the levels morethan 80mThe time and depthmaps of all horizons show thatthere is a dipping toward the north of the study area as thetime and depth values increase toward the north (Figures 10to 13)
42 Isochore Maps Two isochore thickness maps were con-structed for the two pay zones ldquolevel III lowerrdquo and ldquolevelIII mainrdquo Uncertainties affect these elements throughoutthe entire interpretation process They have some bearingon the geometric shape and subsequently on the grossreservoir volume (GRV) of the Baltim fields The increaseof the gross reservoir volume (GRV) leads subsequently to
0
0 00
0
0
0
00
0
00
0 0
150 150150
BE1
BE2
BE9
BN1BN2
BNE1
BS
6000
12000
18000
24000N
1000
1004
1008
1012
1016
1020
1024
1028
1032
times103
1000
1004
1008
1012
1016
1020
1024
1028
1032
times103
620000 628000 636000 644000
620000 628000 636000 644000
CI = 30m
0 2 4 6 8 10(km)
Thic
knes
s (m
)
minus000
0
BE4
Figure 15 Thickness map of level III lower
the increase of the net pay thickness volumes of hydrocar-bons in place reserves and production profiles For level IIImain the thickness varies between 0 and 190m (Figure 14)while for level III lower the thickness varies between 0and 210m (Figure 15) These two isochore maps show thatreservoir thickness of both level III main and lower increaseat the center of the Abu Madi Paleovalley and pinch-outand decrease toward the boundaries where the minimumthickness values were observed Thus the assessment ofgeometrical uncertainties is an essential first step in a fieldstudy for evaluation development or optimization purposes
43 Geological Model A simplified fluvial sequence strati-graphic model of the Late Messinian Abu Madi Formationis shown in Figure 16 This architecture forms the basicconceptual model of the AbuMadi reservoirs ldquolevel III mainrdquoand ldquolevel III lowerrdquo used for well correlation and seismic
Figure 16 Stratigraphic architecture of a fluvial depositional sequence influenced by base-level fluctuations for the Abu Madi incisedvalley channel system Each system tract contains a fining upward succession caused by the continuous coastal aggradation and subsequentshallowing of the fluvial graded profile List of abbreviations lowstand system tract (LST) transgressive system tract (TST) highstand systemtract (HST) maximum flooding surface (MFS) and sequence boundary (SB)
interpretation The spatial and temporal relation betweenbraided and meandering river systems is illustrated for asingle base-level cycle At the beginning of the lowstandsystem tract (LST) braided systems develop close to thesource area where the slope is generally steeper sedimentcoarser channels are overloaded and accommodation islow Towards the coastal plain as the fluvial slope becomesflatter meandering systems take over Rivers here carryless sediment are underloaded and therefore usually havesingle channels As their sinuosity increases the stresses onthe banks raise the probability of bank undermining out-of-channel flow and overbank escape of sediments Thismeandering system eventually grades into the estuary or deltafront systemsAlso due to the overall rise andflattening of thefluvial gradients the entire cycle has a fining upward tendencyBut due to the interaction between sediment supply and therate of accommodation creation at the shoreline the entiresystem progrades or retrogrades during the three stages ofbase-level rise Furthermore two sudden facies shifts may bepresent during the base-level rise cycle
As apparent from Figure 16 transgressions in fluvial sys-temsmay cause estuarine or lagoonal deposits butmore oftenthey are associated with a higher occurrence of floodplaindeposits when a marine influence remains restricted to
areas further basinwards Floodplain deposits are hardly evercontinuous over large areas due to avulsions and channelmigrations [18ndash20] Also overbank deposits and crevassesplays may hinder successful floodplain identification It istherefore often difficult and unreliable to correlate fluvialsequences based on maximum flooding surface (MFS) Thisopposed to the marine realm where the MFS is often betterdeveloped than the sequence boundary (SB) simply due tothe fact that subaerial erosion does not extend below the sealevel In fluvial settings the development of erosional surfacescan be highly heterogeneous due to incisions but theirpreservation potential is much higher due to the increasingaccommodation following the base-level lowstand This incontrast to the MFS which is trailed by a usually thinsand layer developed the highstand system tract (HST) andsubsequent base-level fall It is therefore a common practiceto correlate fluvial succession based on SBs and devise asequence stratigraphic framework in accordance with this
44 3D Geometric Modeling Reservoir modeling is playingan increasingly important role in developing and producinghydrocarbon reserves Various technologies used to under-stand a prospective reservoir provide information at manydifferent scales Core plugs are a few inches in size Well
10 International Journal of Geophysics
Elev
atio
n de
pth
(m)
BS
BE3
BE8BE9
BE5BN2BNE1
BN5BN1
BE2BE10
BE7BE4BE1
minus4100
minus4000
minus3900
minus3800
minus3700
minus3600
minus3500
minus3400
Figure 17 3D geometric model of Abu Madi reservoirs showing the promising pathway (red dashed line) of the future development wellswhich coincides with the up-to-date locations of drilling wells in the Baltim area
logs can detect properties within a few feet around thewell Seismic imaging covers a huge volume but its typicalresolution is limited to a few meters vertically and tensof meters horizontally [21] Limited by time and capitaldirect sampling of reservoir rock and fluid properties issparse Therefore geologic interpretations based on seismicinformation and understandings of sedimentary processesare used to interpolate or extrapolate the measured datain order to yield complete reservoir geometry descriptionsInformation provided by these technologies is incorporatedinto reservoir models Constructing reservoir models hasbecome a crucial step in resource development as reservoirmodeling provides a venue to integrate and reconcile allavailable data and geologic concepts [21]
One of the key challenges in reservoir modeling isaccurate representation of reservoir geometry includingthe structural framework (ie horizonsmajor depositionalsurfaces that are nearly horizontal and fault surfaces whichcan have arbitrary spatial size and orientation) and detailedstratigraphic layers (Figure 17) The structural frameworksdelineate major compartments of a reservoir and oftenprovide the first order controls on in-place fluid volumesand fluid movement during productionThus it is importantto model the structural frameworks accurately Howeverdespite decades of advances in grid generation across manydisciplines grid generation for practical reservoir modelingand simulation remains a daunting task
In typical structural modeling workflows the first taskis to build a fault network as a set of surfaces and contactsbetween these surfaces This step is itself decomposed intosurface fitting which creates one fault surface from eachfault interpretation and editing in which faults can beextended filtered and connected one to another based on
proximity and modelerrsquos interpretation Then horizons arebuilt from seismic picks conformably to the fault network[22] Fault modeling within Abu Madi reservoirs is a rea-sonably straightforward process since only two faults wereidentified during the seismic interpretation Potential synsed-imentary faults and slumps are apparent within the reservoirbut these were not modeled as they are small in scale andexhibit limited throwsThe faults are all normal displacementand were modeled using a network in which individualfault geometries were classified and their interaction definedGrid-building takes the fault model described above andconstructs a 3D grid within the framework of the reservoir-defining seismic surfaces Seismic surfaces representing topAbu Madi top level III main top level III lower andbottom Abu Madi were depth-converted as a part of theinterpretation process within Petrel software
The final result is a 3D geometric model of Abu Madireservoirs based on well and seismic data (Figure 17) andinvolves the construction of the modeling grid using aframework of seismic surfaces faults and stratigraphic wellties 3D geometric model of Abu Madi reservoirs shows thepromising pathway of the future development wells based onthe integration of seismic and well data in this study whichcoincides with the up-to-date locations of drilling wells inthe Baltim area and locates at the center of the Abu MadiPaleovalley (Figure 17)
5 Conclusions
In conclusion we have seen that the role of geometricmodeling is becoming more important for exploring reser-voir structures 3D geometric modeling provided a usefulmeans towards understanding the structure of Abu Madi
International Journal of Geophysics 11
reservoirs Baltim fields (South East and North) comprisetwo separate gas pools named ldquolevel III lowerrdquo and ldquolevelIII mainrdquo within the upper Messinian Abu Madi FormationThe trap is a structural-stratigraphic type with pinch-outagainst incised AbuMadi Paleovalley boundaries and is fault-bounded in the northern and southern part Identificationof stratigraphic architecture not only helps understand thegeological history but also has implications for hydrocarbonexploration as the confinement of flow in an incised valley hasgreat implications for channel amalgamation and producesfavorable reservoirs with potential two-way closure The AbuMadi reservoirs shape influences the seismic response ofthe incised Abu Madi Paleovalley making it necessary toaccount for 3D effects in order to obtain accurate resultsThe accuracy of the estimated thickness of each Abu Madireservoir is a critical element in assessment of reservesvolumes of hydrocarbons in place and production profilesThe promising locations of the future development wellsbased on the integration of seismic and well data coincidewith the up-to-date locations of drilling wells in the Baltimarea and locate at the center of the Abu Madi Paleovalley 3Dgeometricmodel of AbuMadi reservoir in Baltim area shouldbe kept in mind during future field development decisions
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
The authors wish to express their gratitude to Egyptian Gen-eral Petroleum Corporation (EGPC) and Belayim PetroleumCompany (PETROBEL) for providing the seismic lines welllogs and other relevant data Ministry of Higher Educationamp Scientific Research andMinistry of Petroleum in Egypt arealso acknowledged for promoting advancement in researchand establishing a possible future linkage between the indus-try and university They thank Schlumberger for furnishingthe Petrel software for the seismic interpretation
References
[1] S Dalla H Harsy andM Serazzi ldquoHydrocarbon exploration ina complex incised valley fill an example from the lateMessinianAbu Madi formation (Nile Delta Basin Egypt)rdquo The LeadingEdge vol 16 no 12 pp 1819ndash1826 1997
[2] Egyptian General Petroleum Cooperation (EGPC) Nile DeltaandNorth Sinai A Field Discoveries andHydrocarbon Potentials(A Comprehensive Overview) Egyptian General PetroleumCairo Egypt 1994
[3] M Alfy F Polo and M Shash ldquoThe geology of Abu Madigas fieldrdquo in Proceedings of the 11th Petroleum Exploration andProduction Conference pp 485ndash513 Cairo Egypt 1992
[4] I El Heiny R Rizk and M Hassan ldquoSedimentological modelfor AbuMadi sand reservoir AbuMadi field Nile Delta Egyptrdquoin Proceedings of the EGPC 10th Exploration and ProductionConference pp 1ndash38 Cairo Egypt 1990
[5] J D Pigott and M I Abdel-Fattah ldquoSeismic stratigraphy of theMessinian Nile Delta coastal plain recognition of the fluvial
Regressive Systems Tract and its potential for hydrocarbonexplorationrdquo Journal of African Earth Sciences vol 95 pp 9ndash212014
[6] R A Abu El-Ella ldquoTheNeogene-Quaternary section in theNileDelta Egypt geology and hydrocarbon potentialrdquo Journal ofPetroleum Geology vol 13 no 3 pp 329ndash340 1990
[7] J C Dolson M V Shann S Matbouly C Harwood R Rashedand H Hammouda ldquoThe petroleum potential of Egyptrdquo AAPGMemoir vol 74 pp 453ndash482 2001
[8] M I Abdel-Fattah and R M Slatt ldquoSequence stratigraphiccontrols on reservoir characterization and architecture casestudy of the Messinian Abu Madi incised-valley fill EgyptrdquoCentral European Journal of Geosciences vol 5 no 4 pp 497ndash507 2013
[9] J Harms and J Wray ldquoNile Deltardquo in Geology of Egypt R SaidEd pp 329ndash343 A A Balkema Rotterdam The Netherlands1990
[10] M H Mohamed Evaluation of hydrocarbon potentiality ofMiocene rocks in the Northern portion of Abu Madi Paleovalleyoffshore Mediterranean Sea Egypt [MS thesis] Faculty ofScience Suez Canal University 2012
[11] M I Abdel-Fattah ldquoPetrophysical characteristics of the mes-sinian abu madi formation in the baltim east and north fieldsoffshore Nile delta Egyptrdquo Journal of PetroleumGeology vol 37no 2 pp 183ndash195 2014
[12] A Rizzini F Vezzani V Cococcetta and G Milad ldquoStratigra-phy and sedimentation of a Neogene-Quaternary section in theNile Delta area (ARE)rdquo Marine Geology vol 27 no 3-4 pp327ndash348 1978
[13] M Bacon R Simm and T Redshaw 3-D Seismic InterpretationCambridge University Press New York NY USA 2003
[14] M E Badley Practical Seismic Interpretation InternationalHuman Resources Development Corporation Boston MassUSA 1985
[15] M B Dobrin and C H Savit Introduction to GeophysicalProspecting McGraw-Hill New York NY USA 4th edition1988
[16] O L Anderson and J D Pigott ldquoSeismic technology and lawpartners or adversariesrdquo Energy and Mineral Law Institute vol24 2004
[17] A R Brown Interpretation of Three-Dimensional Seismic DataAmerican Association of Petroleum Geologists and the Societyof Exploration Geophysicists 6th edition 2004
[18] O Catuneanu ldquoSequence stratigraphy of clastic systems con-cepts merits and pitfallsrdquo Journal of African Earth Sciences vol35 no 1 pp 1ndash43 2002
[19] O Catuneanu V Abreu J P Bhattacharya et al ldquoTowardsthe standardization of sequence stratigraphyrdquo Earth-ScienceReviews vol 92 pp 1ndash33 2009
[20] A M Salem J M Ketzer S Morad R R Rizk and I S Al-Aasm ldquoDiagenesis and reservoir-quality evolution of incised-valley sandstone evidence from the Abu Madi gas reservoirs(upper Miocene) the Nile Delta Basin Egyptrdquo Journal ofSedimentary Research vol 75 no 4 pp 572ndash584 2005
[21] L V Branets S S Ghai S L Lyons and X-H Wu ldquoChallengesand technologies in reservoir modelingrdquo Communications inComputational Physics vol 6 no 1 pp 1ndash23 2009
[22] G Caumon G Laurent N Cherpeau et al ldquoStructural frame-work and reservoir gridding current bottlenecks and wayforwardrdquo in Proceedings of the GUSSOWGeoscience Conferencep 8 Banff Canada 2011
Figure 3 Schematic cross section illustrating the sequence stratigraphic framework of the Abu Madi Formation in Baltim fields offshoreNile Delta Egypt [8]
Mediterranean Sea
Nile Delta
N
Hinge Zone
Sinia
0 25 50
Study area
Manzala
Burullus
(km)
32∘00998400
31∘00998400
30∘00998400 30∘00998400
31∘00998400
32∘00998400
29∘30998400 30∘30998400 31∘30998400 32∘30998400
29∘30998400 30∘30998400 31∘30998400 32∘30998400
Figure 4 Hinge zone structural feature [9]
in wells When the time-depth relationship has been fine-tuned all depth indexed well tops will be automaticallyassigned the updated time value
32 Picking Horizons and Structural Features Structuralinterpretation is themost fundamental interpretation activityand includes making maps of horizons and 3D structuralmodel By correlating specific horizons on a seismic line itcan subsequently generate time data which after conversion
to depth help generate structural maps (maps which showthe geologic structure of a feature) and isochron or isopachmaps (maps which show time or thickness of particularintervals resp) [16] These maps are useful in allowingthe mapping of particular outlines and in determining thevolumes of particular reservoir hydrocarbon accumulationsBased on the well-to-seismic tie the horizons to interpretwere chosen in the seismic data The main attention wasfocused on the reservoirs intervals where four horizonswere selected to interpret The selected four horizons forinterpretation are bottom Abu Madi top level III lower toplevel III main and top Abu Madi (Figures 6 7 8 and 9)Top and bottom Abu Madi horizons have been chosen to actas structural framework to constrain the level III lower andmain reservoirs geometry
The interpreted horizons in the seismic sections frombase to top are as follows (Figures 7 to 9)
(i) Bottom Abu Madi the interpretation follows a zerocrossing value along a strongly angular unconformityat the base of the Abu Madi Fm While the acousticcontrast strongly changes along this stratigraphic sur-face the erosional geometry at its base and onlappinghorizons above allows following it (although at timeswith uncertainty) at a regional scale
(ii) Top level III lower and top level III main the inter-preted horizon is a seismic peak locally continuouswhose amplitude is related to decrease in seismic
Figure 5 Well BE1 Depth-OWT relationship with linear depth scales The impedance log reflection coefficient and synthetic seismogramgenerated using the sonic and density logs are included Part of seismic line 2609 is plotted together with the synthetic seismogram at wellBE1
0 2 4 6(km)
S NBE9 BN2 BN1
Tim
e (m
s)
1 2
34
Seismic 2D line [T6685]
BE1 BE6
minus2000
minus2500
minus3000
minus3500
minus4000 Seismic 2D line [T6101]Seismic 2D line [L1967]
BS
BNE1
BN2BE5
BE2BE1 BE4
BE3
BN1
Figure 6 Interpreted arbitrary seismic line consists of T6685 L1967 and T6101 from south to north showing the main four-horizon area((1) bottom Abu Madi (2) top level III lower (3) top level II main and (4) top Abu Madi) and the main two faults in the Baltim area
0 1 2 3(km)Ti
me (
ms)
BE9
minus2750
minus3000
minus3500
minus3250
BN2BE5
BE0
BS
BN3
(a)
0 1 2 3(km)Ti
me (
ms)
BE9
1 2
34minus2750
minus3000
minus3500
minus3250
(b)
Figure 7 Uninterpreted (a) and interpreted (b) seismic line number (L 2660) passing through Baltim East field from west to east directionwhere (1) bottom Abu Madi (2) top level III lower (3) top level II main and (4) top Abu Madi are picked
6 International Journal of GeophysicsTi
me (
ms) minus2750
minus2500
minus3000
minus3250(km)
0 1 2 3
BE1 BE4
L2609
BN2BE5BE0BS
BN3
(a)
(km)Tim
e (m
s)
BE1
1 2
34
0 1 2 3
minus2750
minus2500
minus3000
minus3250
BE4
(b)
Figure 8 Uninterpreted (a) and interpreted (b) seismic line number (L 2609) passing through Baltim East field from west to east directionwhere (1) bottom Abu Madi (2) top level III lower (3) top level II main and (4) top Abu Madi are picked
Tim
e (m
s)
BN1
BN2BE5
BE0BS
BN3
(km)0 1 2 3
minus2500
minus3000
minus3500
(a)Ti
me (
ms)
1 2
34
BN1
(km)0 1 2 3
minus2500
minus3000
minus3500
(b)
Figure 9 Uninterpreted (a) and interpreted (b) seismic line number (L 1889) passing through Baltim North field from west to east directionwhere (1) bottom Abu Madi (2) top level III lower (3) top level II main and (4) top Abu Madi are picked
velocityThe reflectionrsquos strength changes significantlyand is stronger where gas bearing sands determine astrong impedance reduction
(iii) Top Abu Madi the interpreted horizon follows azero crossing value between a strong and continuousthrough-peak couplet representing a decrease in seis-mic velocity
Because of the role faults often play in the entrapment ofhydrocarbons the techniques for finding and mapping faultshave considerable importance [15] Faults planes and theirintersections with horizons are digitized from the screendisplay in a similar way to horizons picking When a faultis picked on a seismic section its intersection will appearon an intersecting seismic section It is much easier to workwith faults on lines crossing them approximately at rightangle than on lines crossing them obliquely where the faultplane crosses the bedding at shallow angle Fault planes andtheir intersectionswith horizons are digitized from the screendisplay in a similar way to horizons picking (Figure 6)
33 Velocity and Depth Conversion Depth conversion ofa time interpretation is computationally simple and canbe quickly repeated whenever new information becomesavailable The physical quantity that relates time to depthis velocity The velocity required for converting time todepth is the P-wave velocity in the vertical direction Itcan be measured directly in a well or extracted indirectlyfrom surface seismic measurements or deduced from acombination of seismic and well measurements [17] In thepresent study the check shot survey records and sonic logswere used as a source of the velocity
The complete interpretation is automatically convertedusing Petrel software The workflow of converting databetween domains within Petrel is split into two processes
(i) make velocity model which defines how the velocityvaries in space
(ii) depth conversion which uses the velocity model tomove data between domains
4 Results and Discussion
41 Time and Depth Contour Maps The picked time valuesand the fault segments locations are posted on the base mapof the study area in order to construct structure time mapsfor the studied horizons (top Abu Madi top level III maintop level III lower and bottom AbuMadi) Then the velocitymodel is used to convert the reflection time to depths in orderto construct the structure depth maps
TopAbuMadi has two-way time (TWT) varying between2871 and 3349ms while depth values vary between 3372 and3651m (Figure 10)TheTWTof level IIImain reservoir variesbetween 2972 and 3449ms while depth values vary between3495 and 3815m (Figure 11) and achieve their maximumvalue towards the northern corner of the study area Level IIIlower reservoir has TWT varying between 3034 and 3532mswhile depth values vary between 3495 and 3943m (Figure 12)and achieve their maximum value towards the northerncorner of the study area For bottom Abu Madi the TWTvaries between 3034 and 3698ms while depth values varybetween 3495 and 4185m (Figure 13)The low-relief areas arelocated in the northern parts of the study area while the high-relief areas are located towards the south
Figure 13 Time and depth structure map of bottom Abu Madi Formation
150
150
150
BE1
BE2
BE4
BE9
BS
BN1BN2
BNE1
000
6000
12000
18000
24000
Thic
knes
s (m
)
1000
1004
1008
1012
1016
1020
1024
1028
1032
1000
1004
1008
1012
1016
1020
1024
1028
1032
times103 times103
620000 628000 636000 644000
620000 628000 636000 644000
CI = 30m
0 2 4 6 8 10(km)
N
Figure 14 Thickness map of level III main
The area was dissected by two main faults (Figure 6)the first one is a great high angle E-W normal fault dippingnorthward in the southern part of Baltim area betweenBaltimSouth andBaltimEast fieldsThe second fault between BaltimNorth and Baltim Northeast fields which are in NE-SWdirection dips to the north and displaces all the levels morethan 80mThe time and depthmaps of all horizons show thatthere is a dipping toward the north of the study area as thetime and depth values increase toward the north (Figures 10to 13)
42 Isochore Maps Two isochore thickness maps were con-structed for the two pay zones ldquolevel III lowerrdquo and ldquolevelIII mainrdquo Uncertainties affect these elements throughoutthe entire interpretation process They have some bearingon the geometric shape and subsequently on the grossreservoir volume (GRV) of the Baltim fields The increaseof the gross reservoir volume (GRV) leads subsequently to
0
0 00
0
0
0
00
0
00
0 0
150 150150
BE1
BE2
BE9
BN1BN2
BNE1
BS
6000
12000
18000
24000N
1000
1004
1008
1012
1016
1020
1024
1028
1032
times103
1000
1004
1008
1012
1016
1020
1024
1028
1032
times103
620000 628000 636000 644000
620000 628000 636000 644000
CI = 30m
0 2 4 6 8 10(km)
Thic
knes
s (m
)
minus000
0
BE4
Figure 15 Thickness map of level III lower
the increase of the net pay thickness volumes of hydrocar-bons in place reserves and production profiles For level IIImain the thickness varies between 0 and 190m (Figure 14)while for level III lower the thickness varies between 0and 210m (Figure 15) These two isochore maps show thatreservoir thickness of both level III main and lower increaseat the center of the Abu Madi Paleovalley and pinch-outand decrease toward the boundaries where the minimumthickness values were observed Thus the assessment ofgeometrical uncertainties is an essential first step in a fieldstudy for evaluation development or optimization purposes
43 Geological Model A simplified fluvial sequence strati-graphic model of the Late Messinian Abu Madi Formationis shown in Figure 16 This architecture forms the basicconceptual model of the AbuMadi reservoirs ldquolevel III mainrdquoand ldquolevel III lowerrdquo used for well correlation and seismic
Figure 16 Stratigraphic architecture of a fluvial depositional sequence influenced by base-level fluctuations for the Abu Madi incisedvalley channel system Each system tract contains a fining upward succession caused by the continuous coastal aggradation and subsequentshallowing of the fluvial graded profile List of abbreviations lowstand system tract (LST) transgressive system tract (TST) highstand systemtract (HST) maximum flooding surface (MFS) and sequence boundary (SB)
interpretation The spatial and temporal relation betweenbraided and meandering river systems is illustrated for asingle base-level cycle At the beginning of the lowstandsystem tract (LST) braided systems develop close to thesource area where the slope is generally steeper sedimentcoarser channels are overloaded and accommodation islow Towards the coastal plain as the fluvial slope becomesflatter meandering systems take over Rivers here carryless sediment are underloaded and therefore usually havesingle channels As their sinuosity increases the stresses onthe banks raise the probability of bank undermining out-of-channel flow and overbank escape of sediments Thismeandering system eventually grades into the estuary or deltafront systemsAlso due to the overall rise andflattening of thefluvial gradients the entire cycle has a fining upward tendencyBut due to the interaction between sediment supply and therate of accommodation creation at the shoreline the entiresystem progrades or retrogrades during the three stages ofbase-level rise Furthermore two sudden facies shifts may bepresent during the base-level rise cycle
As apparent from Figure 16 transgressions in fluvial sys-temsmay cause estuarine or lagoonal deposits butmore oftenthey are associated with a higher occurrence of floodplaindeposits when a marine influence remains restricted to
areas further basinwards Floodplain deposits are hardly evercontinuous over large areas due to avulsions and channelmigrations [18ndash20] Also overbank deposits and crevassesplays may hinder successful floodplain identification It istherefore often difficult and unreliable to correlate fluvialsequences based on maximum flooding surface (MFS) Thisopposed to the marine realm where the MFS is often betterdeveloped than the sequence boundary (SB) simply due tothe fact that subaerial erosion does not extend below the sealevel In fluvial settings the development of erosional surfacescan be highly heterogeneous due to incisions but theirpreservation potential is much higher due to the increasingaccommodation following the base-level lowstand This incontrast to the MFS which is trailed by a usually thinsand layer developed the highstand system tract (HST) andsubsequent base-level fall It is therefore a common practiceto correlate fluvial succession based on SBs and devise asequence stratigraphic framework in accordance with this
44 3D Geometric Modeling Reservoir modeling is playingan increasingly important role in developing and producinghydrocarbon reserves Various technologies used to under-stand a prospective reservoir provide information at manydifferent scales Core plugs are a few inches in size Well
10 International Journal of Geophysics
Elev
atio
n de
pth
(m)
BS
BE3
BE8BE9
BE5BN2BNE1
BN5BN1
BE2BE10
BE7BE4BE1
minus4100
minus4000
minus3900
minus3800
minus3700
minus3600
minus3500
minus3400
Figure 17 3D geometric model of Abu Madi reservoirs showing the promising pathway (red dashed line) of the future development wellswhich coincides with the up-to-date locations of drilling wells in the Baltim area
logs can detect properties within a few feet around thewell Seismic imaging covers a huge volume but its typicalresolution is limited to a few meters vertically and tensof meters horizontally [21] Limited by time and capitaldirect sampling of reservoir rock and fluid properties issparse Therefore geologic interpretations based on seismicinformation and understandings of sedimentary processesare used to interpolate or extrapolate the measured datain order to yield complete reservoir geometry descriptionsInformation provided by these technologies is incorporatedinto reservoir models Constructing reservoir models hasbecome a crucial step in resource development as reservoirmodeling provides a venue to integrate and reconcile allavailable data and geologic concepts [21]
One of the key challenges in reservoir modeling isaccurate representation of reservoir geometry includingthe structural framework (ie horizonsmajor depositionalsurfaces that are nearly horizontal and fault surfaces whichcan have arbitrary spatial size and orientation) and detailedstratigraphic layers (Figure 17) The structural frameworksdelineate major compartments of a reservoir and oftenprovide the first order controls on in-place fluid volumesand fluid movement during productionThus it is importantto model the structural frameworks accurately Howeverdespite decades of advances in grid generation across manydisciplines grid generation for practical reservoir modelingand simulation remains a daunting task
In typical structural modeling workflows the first taskis to build a fault network as a set of surfaces and contactsbetween these surfaces This step is itself decomposed intosurface fitting which creates one fault surface from eachfault interpretation and editing in which faults can beextended filtered and connected one to another based on
proximity and modelerrsquos interpretation Then horizons arebuilt from seismic picks conformably to the fault network[22] Fault modeling within Abu Madi reservoirs is a rea-sonably straightforward process since only two faults wereidentified during the seismic interpretation Potential synsed-imentary faults and slumps are apparent within the reservoirbut these were not modeled as they are small in scale andexhibit limited throwsThe faults are all normal displacementand were modeled using a network in which individualfault geometries were classified and their interaction definedGrid-building takes the fault model described above andconstructs a 3D grid within the framework of the reservoir-defining seismic surfaces Seismic surfaces representing topAbu Madi top level III main top level III lower andbottom Abu Madi were depth-converted as a part of theinterpretation process within Petrel software
The final result is a 3D geometric model of Abu Madireservoirs based on well and seismic data (Figure 17) andinvolves the construction of the modeling grid using aframework of seismic surfaces faults and stratigraphic wellties 3D geometric model of Abu Madi reservoirs shows thepromising pathway of the future development wells based onthe integration of seismic and well data in this study whichcoincides with the up-to-date locations of drilling wells inthe Baltim area and locates at the center of the Abu MadiPaleovalley (Figure 17)
5 Conclusions
In conclusion we have seen that the role of geometricmodeling is becoming more important for exploring reser-voir structures 3D geometric modeling provided a usefulmeans towards understanding the structure of Abu Madi
International Journal of Geophysics 11
reservoirs Baltim fields (South East and North) comprisetwo separate gas pools named ldquolevel III lowerrdquo and ldquolevelIII mainrdquo within the upper Messinian Abu Madi FormationThe trap is a structural-stratigraphic type with pinch-outagainst incised AbuMadi Paleovalley boundaries and is fault-bounded in the northern and southern part Identificationof stratigraphic architecture not only helps understand thegeological history but also has implications for hydrocarbonexploration as the confinement of flow in an incised valley hasgreat implications for channel amalgamation and producesfavorable reservoirs with potential two-way closure The AbuMadi reservoirs shape influences the seismic response ofthe incised Abu Madi Paleovalley making it necessary toaccount for 3D effects in order to obtain accurate resultsThe accuracy of the estimated thickness of each Abu Madireservoir is a critical element in assessment of reservesvolumes of hydrocarbons in place and production profilesThe promising locations of the future development wellsbased on the integration of seismic and well data coincidewith the up-to-date locations of drilling wells in the Baltimarea and locate at the center of the Abu Madi Paleovalley 3Dgeometricmodel of AbuMadi reservoir in Baltim area shouldbe kept in mind during future field development decisions
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
The authors wish to express their gratitude to Egyptian Gen-eral Petroleum Corporation (EGPC) and Belayim PetroleumCompany (PETROBEL) for providing the seismic lines welllogs and other relevant data Ministry of Higher Educationamp Scientific Research andMinistry of Petroleum in Egypt arealso acknowledged for promoting advancement in researchand establishing a possible future linkage between the indus-try and university They thank Schlumberger for furnishingthe Petrel software for the seismic interpretation
References
[1] S Dalla H Harsy andM Serazzi ldquoHydrocarbon exploration ina complex incised valley fill an example from the lateMessinianAbu Madi formation (Nile Delta Basin Egypt)rdquo The LeadingEdge vol 16 no 12 pp 1819ndash1826 1997
[2] Egyptian General Petroleum Cooperation (EGPC) Nile DeltaandNorth Sinai A Field Discoveries andHydrocarbon Potentials(A Comprehensive Overview) Egyptian General PetroleumCairo Egypt 1994
[3] M Alfy F Polo and M Shash ldquoThe geology of Abu Madigas fieldrdquo in Proceedings of the 11th Petroleum Exploration andProduction Conference pp 485ndash513 Cairo Egypt 1992
[4] I El Heiny R Rizk and M Hassan ldquoSedimentological modelfor AbuMadi sand reservoir AbuMadi field Nile Delta Egyptrdquoin Proceedings of the EGPC 10th Exploration and ProductionConference pp 1ndash38 Cairo Egypt 1990
[5] J D Pigott and M I Abdel-Fattah ldquoSeismic stratigraphy of theMessinian Nile Delta coastal plain recognition of the fluvial
Regressive Systems Tract and its potential for hydrocarbonexplorationrdquo Journal of African Earth Sciences vol 95 pp 9ndash212014
[6] R A Abu El-Ella ldquoTheNeogene-Quaternary section in theNileDelta Egypt geology and hydrocarbon potentialrdquo Journal ofPetroleum Geology vol 13 no 3 pp 329ndash340 1990
[7] J C Dolson M V Shann S Matbouly C Harwood R Rashedand H Hammouda ldquoThe petroleum potential of Egyptrdquo AAPGMemoir vol 74 pp 453ndash482 2001
[8] M I Abdel-Fattah and R M Slatt ldquoSequence stratigraphiccontrols on reservoir characterization and architecture casestudy of the Messinian Abu Madi incised-valley fill EgyptrdquoCentral European Journal of Geosciences vol 5 no 4 pp 497ndash507 2013
[9] J Harms and J Wray ldquoNile Deltardquo in Geology of Egypt R SaidEd pp 329ndash343 A A Balkema Rotterdam The Netherlands1990
[10] M H Mohamed Evaluation of hydrocarbon potentiality ofMiocene rocks in the Northern portion of Abu Madi Paleovalleyoffshore Mediterranean Sea Egypt [MS thesis] Faculty ofScience Suez Canal University 2012
[11] M I Abdel-Fattah ldquoPetrophysical characteristics of the mes-sinian abu madi formation in the baltim east and north fieldsoffshore Nile delta Egyptrdquo Journal of PetroleumGeology vol 37no 2 pp 183ndash195 2014
[12] A Rizzini F Vezzani V Cococcetta and G Milad ldquoStratigra-phy and sedimentation of a Neogene-Quaternary section in theNile Delta area (ARE)rdquo Marine Geology vol 27 no 3-4 pp327ndash348 1978
[13] M Bacon R Simm and T Redshaw 3-D Seismic InterpretationCambridge University Press New York NY USA 2003
[14] M E Badley Practical Seismic Interpretation InternationalHuman Resources Development Corporation Boston MassUSA 1985
[15] M B Dobrin and C H Savit Introduction to GeophysicalProspecting McGraw-Hill New York NY USA 4th edition1988
[16] O L Anderson and J D Pigott ldquoSeismic technology and lawpartners or adversariesrdquo Energy and Mineral Law Institute vol24 2004
[17] A R Brown Interpretation of Three-Dimensional Seismic DataAmerican Association of Petroleum Geologists and the Societyof Exploration Geophysicists 6th edition 2004
[18] O Catuneanu ldquoSequence stratigraphy of clastic systems con-cepts merits and pitfallsrdquo Journal of African Earth Sciences vol35 no 1 pp 1ndash43 2002
[19] O Catuneanu V Abreu J P Bhattacharya et al ldquoTowardsthe standardization of sequence stratigraphyrdquo Earth-ScienceReviews vol 92 pp 1ndash33 2009
[20] A M Salem J M Ketzer S Morad R R Rizk and I S Al-Aasm ldquoDiagenesis and reservoir-quality evolution of incised-valley sandstone evidence from the Abu Madi gas reservoirs(upper Miocene) the Nile Delta Basin Egyptrdquo Journal ofSedimentary Research vol 75 no 4 pp 572ndash584 2005
[21] L V Branets S S Ghai S L Lyons and X-H Wu ldquoChallengesand technologies in reservoir modelingrdquo Communications inComputational Physics vol 6 no 1 pp 1ndash23 2009
[22] G Caumon G Laurent N Cherpeau et al ldquoStructural frame-work and reservoir gridding current bottlenecks and wayforwardrdquo in Proceedings of the GUSSOWGeoscience Conferencep 8 Banff Canada 2011
Figure 5 Well BE1 Depth-OWT relationship with linear depth scales The impedance log reflection coefficient and synthetic seismogramgenerated using the sonic and density logs are included Part of seismic line 2609 is plotted together with the synthetic seismogram at wellBE1
0 2 4 6(km)
S NBE9 BN2 BN1
Tim
e (m
s)
1 2
34
Seismic 2D line [T6685]
BE1 BE6
minus2000
minus2500
minus3000
minus3500
minus4000 Seismic 2D line [T6101]Seismic 2D line [L1967]
BS
BNE1
BN2BE5
BE2BE1 BE4
BE3
BN1
Figure 6 Interpreted arbitrary seismic line consists of T6685 L1967 and T6101 from south to north showing the main four-horizon area((1) bottom Abu Madi (2) top level III lower (3) top level II main and (4) top Abu Madi) and the main two faults in the Baltim area
0 1 2 3(km)Ti
me (
ms)
BE9
minus2750
minus3000
minus3500
minus3250
BN2BE5
BE0
BS
BN3
(a)
0 1 2 3(km)Ti
me (
ms)
BE9
1 2
34minus2750
minus3000
minus3500
minus3250
(b)
Figure 7 Uninterpreted (a) and interpreted (b) seismic line number (L 2660) passing through Baltim East field from west to east directionwhere (1) bottom Abu Madi (2) top level III lower (3) top level II main and (4) top Abu Madi are picked
6 International Journal of GeophysicsTi
me (
ms) minus2750
minus2500
minus3000
minus3250(km)
0 1 2 3
BE1 BE4
L2609
BN2BE5BE0BS
BN3
(a)
(km)Tim
e (m
s)
BE1
1 2
34
0 1 2 3
minus2750
minus2500
minus3000
minus3250
BE4
(b)
Figure 8 Uninterpreted (a) and interpreted (b) seismic line number (L 2609) passing through Baltim East field from west to east directionwhere (1) bottom Abu Madi (2) top level III lower (3) top level II main and (4) top Abu Madi are picked
Tim
e (m
s)
BN1
BN2BE5
BE0BS
BN3
(km)0 1 2 3
minus2500
minus3000
minus3500
(a)Ti
me (
ms)
1 2
34
BN1
(km)0 1 2 3
minus2500
minus3000
minus3500
(b)
Figure 9 Uninterpreted (a) and interpreted (b) seismic line number (L 1889) passing through Baltim North field from west to east directionwhere (1) bottom Abu Madi (2) top level III lower (3) top level II main and (4) top Abu Madi are picked
velocityThe reflectionrsquos strength changes significantlyand is stronger where gas bearing sands determine astrong impedance reduction
(iii) Top Abu Madi the interpreted horizon follows azero crossing value between a strong and continuousthrough-peak couplet representing a decrease in seis-mic velocity
Because of the role faults often play in the entrapment ofhydrocarbons the techniques for finding and mapping faultshave considerable importance [15] Faults planes and theirintersections with horizons are digitized from the screendisplay in a similar way to horizons picking When a faultis picked on a seismic section its intersection will appearon an intersecting seismic section It is much easier to workwith faults on lines crossing them approximately at rightangle than on lines crossing them obliquely where the faultplane crosses the bedding at shallow angle Fault planes andtheir intersectionswith horizons are digitized from the screendisplay in a similar way to horizons picking (Figure 6)
33 Velocity and Depth Conversion Depth conversion ofa time interpretation is computationally simple and canbe quickly repeated whenever new information becomesavailable The physical quantity that relates time to depthis velocity The velocity required for converting time todepth is the P-wave velocity in the vertical direction Itcan be measured directly in a well or extracted indirectlyfrom surface seismic measurements or deduced from acombination of seismic and well measurements [17] In thepresent study the check shot survey records and sonic logswere used as a source of the velocity
The complete interpretation is automatically convertedusing Petrel software The workflow of converting databetween domains within Petrel is split into two processes
(i) make velocity model which defines how the velocityvaries in space
(ii) depth conversion which uses the velocity model tomove data between domains
4 Results and Discussion
41 Time and Depth Contour Maps The picked time valuesand the fault segments locations are posted on the base mapof the study area in order to construct structure time mapsfor the studied horizons (top Abu Madi top level III maintop level III lower and bottom AbuMadi) Then the velocitymodel is used to convert the reflection time to depths in orderto construct the structure depth maps
TopAbuMadi has two-way time (TWT) varying between2871 and 3349ms while depth values vary between 3372 and3651m (Figure 10)TheTWTof level IIImain reservoir variesbetween 2972 and 3449ms while depth values vary between3495 and 3815m (Figure 11) and achieve their maximumvalue towards the northern corner of the study area Level IIIlower reservoir has TWT varying between 3034 and 3532mswhile depth values vary between 3495 and 3943m (Figure 12)and achieve their maximum value towards the northerncorner of the study area For bottom Abu Madi the TWTvaries between 3034 and 3698ms while depth values varybetween 3495 and 4185m (Figure 13)The low-relief areas arelocated in the northern parts of the study area while the high-relief areas are located towards the south
Figure 13 Time and depth structure map of bottom Abu Madi Formation
150
150
150
BE1
BE2
BE4
BE9
BS
BN1BN2
BNE1
000
6000
12000
18000
24000
Thic
knes
s (m
)
1000
1004
1008
1012
1016
1020
1024
1028
1032
1000
1004
1008
1012
1016
1020
1024
1028
1032
times103 times103
620000 628000 636000 644000
620000 628000 636000 644000
CI = 30m
0 2 4 6 8 10(km)
N
Figure 14 Thickness map of level III main
The area was dissected by two main faults (Figure 6)the first one is a great high angle E-W normal fault dippingnorthward in the southern part of Baltim area betweenBaltimSouth andBaltimEast fieldsThe second fault between BaltimNorth and Baltim Northeast fields which are in NE-SWdirection dips to the north and displaces all the levels morethan 80mThe time and depthmaps of all horizons show thatthere is a dipping toward the north of the study area as thetime and depth values increase toward the north (Figures 10to 13)
42 Isochore Maps Two isochore thickness maps were con-structed for the two pay zones ldquolevel III lowerrdquo and ldquolevelIII mainrdquo Uncertainties affect these elements throughoutthe entire interpretation process They have some bearingon the geometric shape and subsequently on the grossreservoir volume (GRV) of the Baltim fields The increaseof the gross reservoir volume (GRV) leads subsequently to
0
0 00
0
0
0
00
0
00
0 0
150 150150
BE1
BE2
BE9
BN1BN2
BNE1
BS
6000
12000
18000
24000N
1000
1004
1008
1012
1016
1020
1024
1028
1032
times103
1000
1004
1008
1012
1016
1020
1024
1028
1032
times103
620000 628000 636000 644000
620000 628000 636000 644000
CI = 30m
0 2 4 6 8 10(km)
Thic
knes
s (m
)
minus000
0
BE4
Figure 15 Thickness map of level III lower
the increase of the net pay thickness volumes of hydrocar-bons in place reserves and production profiles For level IIImain the thickness varies between 0 and 190m (Figure 14)while for level III lower the thickness varies between 0and 210m (Figure 15) These two isochore maps show thatreservoir thickness of both level III main and lower increaseat the center of the Abu Madi Paleovalley and pinch-outand decrease toward the boundaries where the minimumthickness values were observed Thus the assessment ofgeometrical uncertainties is an essential first step in a fieldstudy for evaluation development or optimization purposes
43 Geological Model A simplified fluvial sequence strati-graphic model of the Late Messinian Abu Madi Formationis shown in Figure 16 This architecture forms the basicconceptual model of the AbuMadi reservoirs ldquolevel III mainrdquoand ldquolevel III lowerrdquo used for well correlation and seismic
Figure 16 Stratigraphic architecture of a fluvial depositional sequence influenced by base-level fluctuations for the Abu Madi incisedvalley channel system Each system tract contains a fining upward succession caused by the continuous coastal aggradation and subsequentshallowing of the fluvial graded profile List of abbreviations lowstand system tract (LST) transgressive system tract (TST) highstand systemtract (HST) maximum flooding surface (MFS) and sequence boundary (SB)
interpretation The spatial and temporal relation betweenbraided and meandering river systems is illustrated for asingle base-level cycle At the beginning of the lowstandsystem tract (LST) braided systems develop close to thesource area where the slope is generally steeper sedimentcoarser channels are overloaded and accommodation islow Towards the coastal plain as the fluvial slope becomesflatter meandering systems take over Rivers here carryless sediment are underloaded and therefore usually havesingle channels As their sinuosity increases the stresses onthe banks raise the probability of bank undermining out-of-channel flow and overbank escape of sediments Thismeandering system eventually grades into the estuary or deltafront systemsAlso due to the overall rise andflattening of thefluvial gradients the entire cycle has a fining upward tendencyBut due to the interaction between sediment supply and therate of accommodation creation at the shoreline the entiresystem progrades or retrogrades during the three stages ofbase-level rise Furthermore two sudden facies shifts may bepresent during the base-level rise cycle
As apparent from Figure 16 transgressions in fluvial sys-temsmay cause estuarine or lagoonal deposits butmore oftenthey are associated with a higher occurrence of floodplaindeposits when a marine influence remains restricted to
areas further basinwards Floodplain deposits are hardly evercontinuous over large areas due to avulsions and channelmigrations [18ndash20] Also overbank deposits and crevassesplays may hinder successful floodplain identification It istherefore often difficult and unreliable to correlate fluvialsequences based on maximum flooding surface (MFS) Thisopposed to the marine realm where the MFS is often betterdeveloped than the sequence boundary (SB) simply due tothe fact that subaerial erosion does not extend below the sealevel In fluvial settings the development of erosional surfacescan be highly heterogeneous due to incisions but theirpreservation potential is much higher due to the increasingaccommodation following the base-level lowstand This incontrast to the MFS which is trailed by a usually thinsand layer developed the highstand system tract (HST) andsubsequent base-level fall It is therefore a common practiceto correlate fluvial succession based on SBs and devise asequence stratigraphic framework in accordance with this
44 3D Geometric Modeling Reservoir modeling is playingan increasingly important role in developing and producinghydrocarbon reserves Various technologies used to under-stand a prospective reservoir provide information at manydifferent scales Core plugs are a few inches in size Well
10 International Journal of Geophysics
Elev
atio
n de
pth
(m)
BS
BE3
BE8BE9
BE5BN2BNE1
BN5BN1
BE2BE10
BE7BE4BE1
minus4100
minus4000
minus3900
minus3800
minus3700
minus3600
minus3500
minus3400
Figure 17 3D geometric model of Abu Madi reservoirs showing the promising pathway (red dashed line) of the future development wellswhich coincides with the up-to-date locations of drilling wells in the Baltim area
logs can detect properties within a few feet around thewell Seismic imaging covers a huge volume but its typicalresolution is limited to a few meters vertically and tensof meters horizontally [21] Limited by time and capitaldirect sampling of reservoir rock and fluid properties issparse Therefore geologic interpretations based on seismicinformation and understandings of sedimentary processesare used to interpolate or extrapolate the measured datain order to yield complete reservoir geometry descriptionsInformation provided by these technologies is incorporatedinto reservoir models Constructing reservoir models hasbecome a crucial step in resource development as reservoirmodeling provides a venue to integrate and reconcile allavailable data and geologic concepts [21]
One of the key challenges in reservoir modeling isaccurate representation of reservoir geometry includingthe structural framework (ie horizonsmajor depositionalsurfaces that are nearly horizontal and fault surfaces whichcan have arbitrary spatial size and orientation) and detailedstratigraphic layers (Figure 17) The structural frameworksdelineate major compartments of a reservoir and oftenprovide the first order controls on in-place fluid volumesand fluid movement during productionThus it is importantto model the structural frameworks accurately Howeverdespite decades of advances in grid generation across manydisciplines grid generation for practical reservoir modelingand simulation remains a daunting task
In typical structural modeling workflows the first taskis to build a fault network as a set of surfaces and contactsbetween these surfaces This step is itself decomposed intosurface fitting which creates one fault surface from eachfault interpretation and editing in which faults can beextended filtered and connected one to another based on
proximity and modelerrsquos interpretation Then horizons arebuilt from seismic picks conformably to the fault network[22] Fault modeling within Abu Madi reservoirs is a rea-sonably straightforward process since only two faults wereidentified during the seismic interpretation Potential synsed-imentary faults and slumps are apparent within the reservoirbut these were not modeled as they are small in scale andexhibit limited throwsThe faults are all normal displacementand were modeled using a network in which individualfault geometries were classified and their interaction definedGrid-building takes the fault model described above andconstructs a 3D grid within the framework of the reservoir-defining seismic surfaces Seismic surfaces representing topAbu Madi top level III main top level III lower andbottom Abu Madi were depth-converted as a part of theinterpretation process within Petrel software
The final result is a 3D geometric model of Abu Madireservoirs based on well and seismic data (Figure 17) andinvolves the construction of the modeling grid using aframework of seismic surfaces faults and stratigraphic wellties 3D geometric model of Abu Madi reservoirs shows thepromising pathway of the future development wells based onthe integration of seismic and well data in this study whichcoincides with the up-to-date locations of drilling wells inthe Baltim area and locates at the center of the Abu MadiPaleovalley (Figure 17)
5 Conclusions
In conclusion we have seen that the role of geometricmodeling is becoming more important for exploring reser-voir structures 3D geometric modeling provided a usefulmeans towards understanding the structure of Abu Madi
International Journal of Geophysics 11
reservoirs Baltim fields (South East and North) comprisetwo separate gas pools named ldquolevel III lowerrdquo and ldquolevelIII mainrdquo within the upper Messinian Abu Madi FormationThe trap is a structural-stratigraphic type with pinch-outagainst incised AbuMadi Paleovalley boundaries and is fault-bounded in the northern and southern part Identificationof stratigraphic architecture not only helps understand thegeological history but also has implications for hydrocarbonexploration as the confinement of flow in an incised valley hasgreat implications for channel amalgamation and producesfavorable reservoirs with potential two-way closure The AbuMadi reservoirs shape influences the seismic response ofthe incised Abu Madi Paleovalley making it necessary toaccount for 3D effects in order to obtain accurate resultsThe accuracy of the estimated thickness of each Abu Madireservoir is a critical element in assessment of reservesvolumes of hydrocarbons in place and production profilesThe promising locations of the future development wellsbased on the integration of seismic and well data coincidewith the up-to-date locations of drilling wells in the Baltimarea and locate at the center of the Abu Madi Paleovalley 3Dgeometricmodel of AbuMadi reservoir in Baltim area shouldbe kept in mind during future field development decisions
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
The authors wish to express their gratitude to Egyptian Gen-eral Petroleum Corporation (EGPC) and Belayim PetroleumCompany (PETROBEL) for providing the seismic lines welllogs and other relevant data Ministry of Higher Educationamp Scientific Research andMinistry of Petroleum in Egypt arealso acknowledged for promoting advancement in researchand establishing a possible future linkage between the indus-try and university They thank Schlumberger for furnishingthe Petrel software for the seismic interpretation
References
[1] S Dalla H Harsy andM Serazzi ldquoHydrocarbon exploration ina complex incised valley fill an example from the lateMessinianAbu Madi formation (Nile Delta Basin Egypt)rdquo The LeadingEdge vol 16 no 12 pp 1819ndash1826 1997
[2] Egyptian General Petroleum Cooperation (EGPC) Nile DeltaandNorth Sinai A Field Discoveries andHydrocarbon Potentials(A Comprehensive Overview) Egyptian General PetroleumCairo Egypt 1994
[3] M Alfy F Polo and M Shash ldquoThe geology of Abu Madigas fieldrdquo in Proceedings of the 11th Petroleum Exploration andProduction Conference pp 485ndash513 Cairo Egypt 1992
[4] I El Heiny R Rizk and M Hassan ldquoSedimentological modelfor AbuMadi sand reservoir AbuMadi field Nile Delta Egyptrdquoin Proceedings of the EGPC 10th Exploration and ProductionConference pp 1ndash38 Cairo Egypt 1990
[5] J D Pigott and M I Abdel-Fattah ldquoSeismic stratigraphy of theMessinian Nile Delta coastal plain recognition of the fluvial
Regressive Systems Tract and its potential for hydrocarbonexplorationrdquo Journal of African Earth Sciences vol 95 pp 9ndash212014
[6] R A Abu El-Ella ldquoTheNeogene-Quaternary section in theNileDelta Egypt geology and hydrocarbon potentialrdquo Journal ofPetroleum Geology vol 13 no 3 pp 329ndash340 1990
[7] J C Dolson M V Shann S Matbouly C Harwood R Rashedand H Hammouda ldquoThe petroleum potential of Egyptrdquo AAPGMemoir vol 74 pp 453ndash482 2001
[8] M I Abdel-Fattah and R M Slatt ldquoSequence stratigraphiccontrols on reservoir characterization and architecture casestudy of the Messinian Abu Madi incised-valley fill EgyptrdquoCentral European Journal of Geosciences vol 5 no 4 pp 497ndash507 2013
[9] J Harms and J Wray ldquoNile Deltardquo in Geology of Egypt R SaidEd pp 329ndash343 A A Balkema Rotterdam The Netherlands1990
[10] M H Mohamed Evaluation of hydrocarbon potentiality ofMiocene rocks in the Northern portion of Abu Madi Paleovalleyoffshore Mediterranean Sea Egypt [MS thesis] Faculty ofScience Suez Canal University 2012
[11] M I Abdel-Fattah ldquoPetrophysical characteristics of the mes-sinian abu madi formation in the baltim east and north fieldsoffshore Nile delta Egyptrdquo Journal of PetroleumGeology vol 37no 2 pp 183ndash195 2014
[12] A Rizzini F Vezzani V Cococcetta and G Milad ldquoStratigra-phy and sedimentation of a Neogene-Quaternary section in theNile Delta area (ARE)rdquo Marine Geology vol 27 no 3-4 pp327ndash348 1978
[13] M Bacon R Simm and T Redshaw 3-D Seismic InterpretationCambridge University Press New York NY USA 2003
[14] M E Badley Practical Seismic Interpretation InternationalHuman Resources Development Corporation Boston MassUSA 1985
[15] M B Dobrin and C H Savit Introduction to GeophysicalProspecting McGraw-Hill New York NY USA 4th edition1988
[16] O L Anderson and J D Pigott ldquoSeismic technology and lawpartners or adversariesrdquo Energy and Mineral Law Institute vol24 2004
[17] A R Brown Interpretation of Three-Dimensional Seismic DataAmerican Association of Petroleum Geologists and the Societyof Exploration Geophysicists 6th edition 2004
[18] O Catuneanu ldquoSequence stratigraphy of clastic systems con-cepts merits and pitfallsrdquo Journal of African Earth Sciences vol35 no 1 pp 1ndash43 2002
[19] O Catuneanu V Abreu J P Bhattacharya et al ldquoTowardsthe standardization of sequence stratigraphyrdquo Earth-ScienceReviews vol 92 pp 1ndash33 2009
[20] A M Salem J M Ketzer S Morad R R Rizk and I S Al-Aasm ldquoDiagenesis and reservoir-quality evolution of incised-valley sandstone evidence from the Abu Madi gas reservoirs(upper Miocene) the Nile Delta Basin Egyptrdquo Journal ofSedimentary Research vol 75 no 4 pp 572ndash584 2005
[21] L V Branets S S Ghai S L Lyons and X-H Wu ldquoChallengesand technologies in reservoir modelingrdquo Communications inComputational Physics vol 6 no 1 pp 1ndash23 2009
[22] G Caumon G Laurent N Cherpeau et al ldquoStructural frame-work and reservoir gridding current bottlenecks and wayforwardrdquo in Proceedings of the GUSSOWGeoscience Conferencep 8 Banff Canada 2011
Figure 8 Uninterpreted (a) and interpreted (b) seismic line number (L 2609) passing through Baltim East field from west to east directionwhere (1) bottom Abu Madi (2) top level III lower (3) top level II main and (4) top Abu Madi are picked
Tim
e (m
s)
BN1
BN2BE5
BE0BS
BN3
(km)0 1 2 3
minus2500
minus3000
minus3500
(a)Ti
me (
ms)
1 2
34
BN1
(km)0 1 2 3
minus2500
minus3000
minus3500
(b)
Figure 9 Uninterpreted (a) and interpreted (b) seismic line number (L 1889) passing through Baltim North field from west to east directionwhere (1) bottom Abu Madi (2) top level III lower (3) top level II main and (4) top Abu Madi are picked
velocityThe reflectionrsquos strength changes significantlyand is stronger where gas bearing sands determine astrong impedance reduction
(iii) Top Abu Madi the interpreted horizon follows azero crossing value between a strong and continuousthrough-peak couplet representing a decrease in seis-mic velocity
Because of the role faults often play in the entrapment ofhydrocarbons the techniques for finding and mapping faultshave considerable importance [15] Faults planes and theirintersections with horizons are digitized from the screendisplay in a similar way to horizons picking When a faultis picked on a seismic section its intersection will appearon an intersecting seismic section It is much easier to workwith faults on lines crossing them approximately at rightangle than on lines crossing them obliquely where the faultplane crosses the bedding at shallow angle Fault planes andtheir intersectionswith horizons are digitized from the screendisplay in a similar way to horizons picking (Figure 6)
33 Velocity and Depth Conversion Depth conversion ofa time interpretation is computationally simple and canbe quickly repeated whenever new information becomesavailable The physical quantity that relates time to depthis velocity The velocity required for converting time todepth is the P-wave velocity in the vertical direction Itcan be measured directly in a well or extracted indirectlyfrom surface seismic measurements or deduced from acombination of seismic and well measurements [17] In thepresent study the check shot survey records and sonic logswere used as a source of the velocity
The complete interpretation is automatically convertedusing Petrel software The workflow of converting databetween domains within Petrel is split into two processes
(i) make velocity model which defines how the velocityvaries in space
(ii) depth conversion which uses the velocity model tomove data between domains
4 Results and Discussion
41 Time and Depth Contour Maps The picked time valuesand the fault segments locations are posted on the base mapof the study area in order to construct structure time mapsfor the studied horizons (top Abu Madi top level III maintop level III lower and bottom AbuMadi) Then the velocitymodel is used to convert the reflection time to depths in orderto construct the structure depth maps
TopAbuMadi has two-way time (TWT) varying between2871 and 3349ms while depth values vary between 3372 and3651m (Figure 10)TheTWTof level IIImain reservoir variesbetween 2972 and 3449ms while depth values vary between3495 and 3815m (Figure 11) and achieve their maximumvalue towards the northern corner of the study area Level IIIlower reservoir has TWT varying between 3034 and 3532mswhile depth values vary between 3495 and 3943m (Figure 12)and achieve their maximum value towards the northerncorner of the study area For bottom Abu Madi the TWTvaries between 3034 and 3698ms while depth values varybetween 3495 and 4185m (Figure 13)The low-relief areas arelocated in the northern parts of the study area while the high-relief areas are located towards the south
Figure 13 Time and depth structure map of bottom Abu Madi Formation
150
150
150
BE1
BE2
BE4
BE9
BS
BN1BN2
BNE1
000
6000
12000
18000
24000
Thic
knes
s (m
)
1000
1004
1008
1012
1016
1020
1024
1028
1032
1000
1004
1008
1012
1016
1020
1024
1028
1032
times103 times103
620000 628000 636000 644000
620000 628000 636000 644000
CI = 30m
0 2 4 6 8 10(km)
N
Figure 14 Thickness map of level III main
The area was dissected by two main faults (Figure 6)the first one is a great high angle E-W normal fault dippingnorthward in the southern part of Baltim area betweenBaltimSouth andBaltimEast fieldsThe second fault between BaltimNorth and Baltim Northeast fields which are in NE-SWdirection dips to the north and displaces all the levels morethan 80mThe time and depthmaps of all horizons show thatthere is a dipping toward the north of the study area as thetime and depth values increase toward the north (Figures 10to 13)
42 Isochore Maps Two isochore thickness maps were con-structed for the two pay zones ldquolevel III lowerrdquo and ldquolevelIII mainrdquo Uncertainties affect these elements throughoutthe entire interpretation process They have some bearingon the geometric shape and subsequently on the grossreservoir volume (GRV) of the Baltim fields The increaseof the gross reservoir volume (GRV) leads subsequently to
0
0 00
0
0
0
00
0
00
0 0
150 150150
BE1
BE2
BE9
BN1BN2
BNE1
BS
6000
12000
18000
24000N
1000
1004
1008
1012
1016
1020
1024
1028
1032
times103
1000
1004
1008
1012
1016
1020
1024
1028
1032
times103
620000 628000 636000 644000
620000 628000 636000 644000
CI = 30m
0 2 4 6 8 10(km)
Thic
knes
s (m
)
minus000
0
BE4
Figure 15 Thickness map of level III lower
the increase of the net pay thickness volumes of hydrocar-bons in place reserves and production profiles For level IIImain the thickness varies between 0 and 190m (Figure 14)while for level III lower the thickness varies between 0and 210m (Figure 15) These two isochore maps show thatreservoir thickness of both level III main and lower increaseat the center of the Abu Madi Paleovalley and pinch-outand decrease toward the boundaries where the minimumthickness values were observed Thus the assessment ofgeometrical uncertainties is an essential first step in a fieldstudy for evaluation development or optimization purposes
43 Geological Model A simplified fluvial sequence strati-graphic model of the Late Messinian Abu Madi Formationis shown in Figure 16 This architecture forms the basicconceptual model of the AbuMadi reservoirs ldquolevel III mainrdquoand ldquolevel III lowerrdquo used for well correlation and seismic
Figure 16 Stratigraphic architecture of a fluvial depositional sequence influenced by base-level fluctuations for the Abu Madi incisedvalley channel system Each system tract contains a fining upward succession caused by the continuous coastal aggradation and subsequentshallowing of the fluvial graded profile List of abbreviations lowstand system tract (LST) transgressive system tract (TST) highstand systemtract (HST) maximum flooding surface (MFS) and sequence boundary (SB)
interpretation The spatial and temporal relation betweenbraided and meandering river systems is illustrated for asingle base-level cycle At the beginning of the lowstandsystem tract (LST) braided systems develop close to thesource area where the slope is generally steeper sedimentcoarser channels are overloaded and accommodation islow Towards the coastal plain as the fluvial slope becomesflatter meandering systems take over Rivers here carryless sediment are underloaded and therefore usually havesingle channels As their sinuosity increases the stresses onthe banks raise the probability of bank undermining out-of-channel flow and overbank escape of sediments Thismeandering system eventually grades into the estuary or deltafront systemsAlso due to the overall rise andflattening of thefluvial gradients the entire cycle has a fining upward tendencyBut due to the interaction between sediment supply and therate of accommodation creation at the shoreline the entiresystem progrades or retrogrades during the three stages ofbase-level rise Furthermore two sudden facies shifts may bepresent during the base-level rise cycle
As apparent from Figure 16 transgressions in fluvial sys-temsmay cause estuarine or lagoonal deposits butmore oftenthey are associated with a higher occurrence of floodplaindeposits when a marine influence remains restricted to
areas further basinwards Floodplain deposits are hardly evercontinuous over large areas due to avulsions and channelmigrations [18ndash20] Also overbank deposits and crevassesplays may hinder successful floodplain identification It istherefore often difficult and unreliable to correlate fluvialsequences based on maximum flooding surface (MFS) Thisopposed to the marine realm where the MFS is often betterdeveloped than the sequence boundary (SB) simply due tothe fact that subaerial erosion does not extend below the sealevel In fluvial settings the development of erosional surfacescan be highly heterogeneous due to incisions but theirpreservation potential is much higher due to the increasingaccommodation following the base-level lowstand This incontrast to the MFS which is trailed by a usually thinsand layer developed the highstand system tract (HST) andsubsequent base-level fall It is therefore a common practiceto correlate fluvial succession based on SBs and devise asequence stratigraphic framework in accordance with this
44 3D Geometric Modeling Reservoir modeling is playingan increasingly important role in developing and producinghydrocarbon reserves Various technologies used to under-stand a prospective reservoir provide information at manydifferent scales Core plugs are a few inches in size Well
10 International Journal of Geophysics
Elev
atio
n de
pth
(m)
BS
BE3
BE8BE9
BE5BN2BNE1
BN5BN1
BE2BE10
BE7BE4BE1
minus4100
minus4000
minus3900
minus3800
minus3700
minus3600
minus3500
minus3400
Figure 17 3D geometric model of Abu Madi reservoirs showing the promising pathway (red dashed line) of the future development wellswhich coincides with the up-to-date locations of drilling wells in the Baltim area
logs can detect properties within a few feet around thewell Seismic imaging covers a huge volume but its typicalresolution is limited to a few meters vertically and tensof meters horizontally [21] Limited by time and capitaldirect sampling of reservoir rock and fluid properties issparse Therefore geologic interpretations based on seismicinformation and understandings of sedimentary processesare used to interpolate or extrapolate the measured datain order to yield complete reservoir geometry descriptionsInformation provided by these technologies is incorporatedinto reservoir models Constructing reservoir models hasbecome a crucial step in resource development as reservoirmodeling provides a venue to integrate and reconcile allavailable data and geologic concepts [21]
One of the key challenges in reservoir modeling isaccurate representation of reservoir geometry includingthe structural framework (ie horizonsmajor depositionalsurfaces that are nearly horizontal and fault surfaces whichcan have arbitrary spatial size and orientation) and detailedstratigraphic layers (Figure 17) The structural frameworksdelineate major compartments of a reservoir and oftenprovide the first order controls on in-place fluid volumesand fluid movement during productionThus it is importantto model the structural frameworks accurately Howeverdespite decades of advances in grid generation across manydisciplines grid generation for practical reservoir modelingand simulation remains a daunting task
In typical structural modeling workflows the first taskis to build a fault network as a set of surfaces and contactsbetween these surfaces This step is itself decomposed intosurface fitting which creates one fault surface from eachfault interpretation and editing in which faults can beextended filtered and connected one to another based on
proximity and modelerrsquos interpretation Then horizons arebuilt from seismic picks conformably to the fault network[22] Fault modeling within Abu Madi reservoirs is a rea-sonably straightforward process since only two faults wereidentified during the seismic interpretation Potential synsed-imentary faults and slumps are apparent within the reservoirbut these were not modeled as they are small in scale andexhibit limited throwsThe faults are all normal displacementand were modeled using a network in which individualfault geometries were classified and their interaction definedGrid-building takes the fault model described above andconstructs a 3D grid within the framework of the reservoir-defining seismic surfaces Seismic surfaces representing topAbu Madi top level III main top level III lower andbottom Abu Madi were depth-converted as a part of theinterpretation process within Petrel software
The final result is a 3D geometric model of Abu Madireservoirs based on well and seismic data (Figure 17) andinvolves the construction of the modeling grid using aframework of seismic surfaces faults and stratigraphic wellties 3D geometric model of Abu Madi reservoirs shows thepromising pathway of the future development wells based onthe integration of seismic and well data in this study whichcoincides with the up-to-date locations of drilling wells inthe Baltim area and locates at the center of the Abu MadiPaleovalley (Figure 17)
5 Conclusions
In conclusion we have seen that the role of geometricmodeling is becoming more important for exploring reser-voir structures 3D geometric modeling provided a usefulmeans towards understanding the structure of Abu Madi
International Journal of Geophysics 11
reservoirs Baltim fields (South East and North) comprisetwo separate gas pools named ldquolevel III lowerrdquo and ldquolevelIII mainrdquo within the upper Messinian Abu Madi FormationThe trap is a structural-stratigraphic type with pinch-outagainst incised AbuMadi Paleovalley boundaries and is fault-bounded in the northern and southern part Identificationof stratigraphic architecture not only helps understand thegeological history but also has implications for hydrocarbonexploration as the confinement of flow in an incised valley hasgreat implications for channel amalgamation and producesfavorable reservoirs with potential two-way closure The AbuMadi reservoirs shape influences the seismic response ofthe incised Abu Madi Paleovalley making it necessary toaccount for 3D effects in order to obtain accurate resultsThe accuracy of the estimated thickness of each Abu Madireservoir is a critical element in assessment of reservesvolumes of hydrocarbons in place and production profilesThe promising locations of the future development wellsbased on the integration of seismic and well data coincidewith the up-to-date locations of drilling wells in the Baltimarea and locate at the center of the Abu Madi Paleovalley 3Dgeometricmodel of AbuMadi reservoir in Baltim area shouldbe kept in mind during future field development decisions
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
The authors wish to express their gratitude to Egyptian Gen-eral Petroleum Corporation (EGPC) and Belayim PetroleumCompany (PETROBEL) for providing the seismic lines welllogs and other relevant data Ministry of Higher Educationamp Scientific Research andMinistry of Petroleum in Egypt arealso acknowledged for promoting advancement in researchand establishing a possible future linkage between the indus-try and university They thank Schlumberger for furnishingthe Petrel software for the seismic interpretation
References
[1] S Dalla H Harsy andM Serazzi ldquoHydrocarbon exploration ina complex incised valley fill an example from the lateMessinianAbu Madi formation (Nile Delta Basin Egypt)rdquo The LeadingEdge vol 16 no 12 pp 1819ndash1826 1997
[2] Egyptian General Petroleum Cooperation (EGPC) Nile DeltaandNorth Sinai A Field Discoveries andHydrocarbon Potentials(A Comprehensive Overview) Egyptian General PetroleumCairo Egypt 1994
[3] M Alfy F Polo and M Shash ldquoThe geology of Abu Madigas fieldrdquo in Proceedings of the 11th Petroleum Exploration andProduction Conference pp 485ndash513 Cairo Egypt 1992
[4] I El Heiny R Rizk and M Hassan ldquoSedimentological modelfor AbuMadi sand reservoir AbuMadi field Nile Delta Egyptrdquoin Proceedings of the EGPC 10th Exploration and ProductionConference pp 1ndash38 Cairo Egypt 1990
[5] J D Pigott and M I Abdel-Fattah ldquoSeismic stratigraphy of theMessinian Nile Delta coastal plain recognition of the fluvial
Regressive Systems Tract and its potential for hydrocarbonexplorationrdquo Journal of African Earth Sciences vol 95 pp 9ndash212014
[6] R A Abu El-Ella ldquoTheNeogene-Quaternary section in theNileDelta Egypt geology and hydrocarbon potentialrdquo Journal ofPetroleum Geology vol 13 no 3 pp 329ndash340 1990
[7] J C Dolson M V Shann S Matbouly C Harwood R Rashedand H Hammouda ldquoThe petroleum potential of Egyptrdquo AAPGMemoir vol 74 pp 453ndash482 2001
[8] M I Abdel-Fattah and R M Slatt ldquoSequence stratigraphiccontrols on reservoir characterization and architecture casestudy of the Messinian Abu Madi incised-valley fill EgyptrdquoCentral European Journal of Geosciences vol 5 no 4 pp 497ndash507 2013
[9] J Harms and J Wray ldquoNile Deltardquo in Geology of Egypt R SaidEd pp 329ndash343 A A Balkema Rotterdam The Netherlands1990
[10] M H Mohamed Evaluation of hydrocarbon potentiality ofMiocene rocks in the Northern portion of Abu Madi Paleovalleyoffshore Mediterranean Sea Egypt [MS thesis] Faculty ofScience Suez Canal University 2012
[11] M I Abdel-Fattah ldquoPetrophysical characteristics of the mes-sinian abu madi formation in the baltim east and north fieldsoffshore Nile delta Egyptrdquo Journal of PetroleumGeology vol 37no 2 pp 183ndash195 2014
[12] A Rizzini F Vezzani V Cococcetta and G Milad ldquoStratigra-phy and sedimentation of a Neogene-Quaternary section in theNile Delta area (ARE)rdquo Marine Geology vol 27 no 3-4 pp327ndash348 1978
[13] M Bacon R Simm and T Redshaw 3-D Seismic InterpretationCambridge University Press New York NY USA 2003
[14] M E Badley Practical Seismic Interpretation InternationalHuman Resources Development Corporation Boston MassUSA 1985
[15] M B Dobrin and C H Savit Introduction to GeophysicalProspecting McGraw-Hill New York NY USA 4th edition1988
[16] O L Anderson and J D Pigott ldquoSeismic technology and lawpartners or adversariesrdquo Energy and Mineral Law Institute vol24 2004
[17] A R Brown Interpretation of Three-Dimensional Seismic DataAmerican Association of Petroleum Geologists and the Societyof Exploration Geophysicists 6th edition 2004
[18] O Catuneanu ldquoSequence stratigraphy of clastic systems con-cepts merits and pitfallsrdquo Journal of African Earth Sciences vol35 no 1 pp 1ndash43 2002
[19] O Catuneanu V Abreu J P Bhattacharya et al ldquoTowardsthe standardization of sequence stratigraphyrdquo Earth-ScienceReviews vol 92 pp 1ndash33 2009
[20] A M Salem J M Ketzer S Morad R R Rizk and I S Al-Aasm ldquoDiagenesis and reservoir-quality evolution of incised-valley sandstone evidence from the Abu Madi gas reservoirs(upper Miocene) the Nile Delta Basin Egyptrdquo Journal ofSedimentary Research vol 75 no 4 pp 572ndash584 2005
[21] L V Branets S S Ghai S L Lyons and X-H Wu ldquoChallengesand technologies in reservoir modelingrdquo Communications inComputational Physics vol 6 no 1 pp 1ndash23 2009
[22] G Caumon G Laurent N Cherpeau et al ldquoStructural frame-work and reservoir gridding current bottlenecks and wayforwardrdquo in Proceedings of the GUSSOWGeoscience Conferencep 8 Banff Canada 2011
Figure 13 Time and depth structure map of bottom Abu Madi Formation
150
150
150
BE1
BE2
BE4
BE9
BS
BN1BN2
BNE1
000
6000
12000
18000
24000
Thic
knes
s (m
)
1000
1004
1008
1012
1016
1020
1024
1028
1032
1000
1004
1008
1012
1016
1020
1024
1028
1032
times103 times103
620000 628000 636000 644000
620000 628000 636000 644000
CI = 30m
0 2 4 6 8 10(km)
N
Figure 14 Thickness map of level III main
The area was dissected by two main faults (Figure 6)the first one is a great high angle E-W normal fault dippingnorthward in the southern part of Baltim area betweenBaltimSouth andBaltimEast fieldsThe second fault between BaltimNorth and Baltim Northeast fields which are in NE-SWdirection dips to the north and displaces all the levels morethan 80mThe time and depthmaps of all horizons show thatthere is a dipping toward the north of the study area as thetime and depth values increase toward the north (Figures 10to 13)
42 Isochore Maps Two isochore thickness maps were con-structed for the two pay zones ldquolevel III lowerrdquo and ldquolevelIII mainrdquo Uncertainties affect these elements throughoutthe entire interpretation process They have some bearingon the geometric shape and subsequently on the grossreservoir volume (GRV) of the Baltim fields The increaseof the gross reservoir volume (GRV) leads subsequently to
0
0 00
0
0
0
00
0
00
0 0
150 150150
BE1
BE2
BE9
BN1BN2
BNE1
BS
6000
12000
18000
24000N
1000
1004
1008
1012
1016
1020
1024
1028
1032
times103
1000
1004
1008
1012
1016
1020
1024
1028
1032
times103
620000 628000 636000 644000
620000 628000 636000 644000
CI = 30m
0 2 4 6 8 10(km)
Thic
knes
s (m
)
minus000
0
BE4
Figure 15 Thickness map of level III lower
the increase of the net pay thickness volumes of hydrocar-bons in place reserves and production profiles For level IIImain the thickness varies between 0 and 190m (Figure 14)while for level III lower the thickness varies between 0and 210m (Figure 15) These two isochore maps show thatreservoir thickness of both level III main and lower increaseat the center of the Abu Madi Paleovalley and pinch-outand decrease toward the boundaries where the minimumthickness values were observed Thus the assessment ofgeometrical uncertainties is an essential first step in a fieldstudy for evaluation development or optimization purposes
43 Geological Model A simplified fluvial sequence strati-graphic model of the Late Messinian Abu Madi Formationis shown in Figure 16 This architecture forms the basicconceptual model of the AbuMadi reservoirs ldquolevel III mainrdquoand ldquolevel III lowerrdquo used for well correlation and seismic
Figure 16 Stratigraphic architecture of a fluvial depositional sequence influenced by base-level fluctuations for the Abu Madi incisedvalley channel system Each system tract contains a fining upward succession caused by the continuous coastal aggradation and subsequentshallowing of the fluvial graded profile List of abbreviations lowstand system tract (LST) transgressive system tract (TST) highstand systemtract (HST) maximum flooding surface (MFS) and sequence boundary (SB)
interpretation The spatial and temporal relation betweenbraided and meandering river systems is illustrated for asingle base-level cycle At the beginning of the lowstandsystem tract (LST) braided systems develop close to thesource area where the slope is generally steeper sedimentcoarser channels are overloaded and accommodation islow Towards the coastal plain as the fluvial slope becomesflatter meandering systems take over Rivers here carryless sediment are underloaded and therefore usually havesingle channels As their sinuosity increases the stresses onthe banks raise the probability of bank undermining out-of-channel flow and overbank escape of sediments Thismeandering system eventually grades into the estuary or deltafront systemsAlso due to the overall rise andflattening of thefluvial gradients the entire cycle has a fining upward tendencyBut due to the interaction between sediment supply and therate of accommodation creation at the shoreline the entiresystem progrades or retrogrades during the three stages ofbase-level rise Furthermore two sudden facies shifts may bepresent during the base-level rise cycle
As apparent from Figure 16 transgressions in fluvial sys-temsmay cause estuarine or lagoonal deposits butmore oftenthey are associated with a higher occurrence of floodplaindeposits when a marine influence remains restricted to
areas further basinwards Floodplain deposits are hardly evercontinuous over large areas due to avulsions and channelmigrations [18ndash20] Also overbank deposits and crevassesplays may hinder successful floodplain identification It istherefore often difficult and unreliable to correlate fluvialsequences based on maximum flooding surface (MFS) Thisopposed to the marine realm where the MFS is often betterdeveloped than the sequence boundary (SB) simply due tothe fact that subaerial erosion does not extend below the sealevel In fluvial settings the development of erosional surfacescan be highly heterogeneous due to incisions but theirpreservation potential is much higher due to the increasingaccommodation following the base-level lowstand This incontrast to the MFS which is trailed by a usually thinsand layer developed the highstand system tract (HST) andsubsequent base-level fall It is therefore a common practiceto correlate fluvial succession based on SBs and devise asequence stratigraphic framework in accordance with this
44 3D Geometric Modeling Reservoir modeling is playingan increasingly important role in developing and producinghydrocarbon reserves Various technologies used to under-stand a prospective reservoir provide information at manydifferent scales Core plugs are a few inches in size Well
10 International Journal of Geophysics
Elev
atio
n de
pth
(m)
BS
BE3
BE8BE9
BE5BN2BNE1
BN5BN1
BE2BE10
BE7BE4BE1
minus4100
minus4000
minus3900
minus3800
minus3700
minus3600
minus3500
minus3400
Figure 17 3D geometric model of Abu Madi reservoirs showing the promising pathway (red dashed line) of the future development wellswhich coincides with the up-to-date locations of drilling wells in the Baltim area
logs can detect properties within a few feet around thewell Seismic imaging covers a huge volume but its typicalresolution is limited to a few meters vertically and tensof meters horizontally [21] Limited by time and capitaldirect sampling of reservoir rock and fluid properties issparse Therefore geologic interpretations based on seismicinformation and understandings of sedimentary processesare used to interpolate or extrapolate the measured datain order to yield complete reservoir geometry descriptionsInformation provided by these technologies is incorporatedinto reservoir models Constructing reservoir models hasbecome a crucial step in resource development as reservoirmodeling provides a venue to integrate and reconcile allavailable data and geologic concepts [21]
One of the key challenges in reservoir modeling isaccurate representation of reservoir geometry includingthe structural framework (ie horizonsmajor depositionalsurfaces that are nearly horizontal and fault surfaces whichcan have arbitrary spatial size and orientation) and detailedstratigraphic layers (Figure 17) The structural frameworksdelineate major compartments of a reservoir and oftenprovide the first order controls on in-place fluid volumesand fluid movement during productionThus it is importantto model the structural frameworks accurately Howeverdespite decades of advances in grid generation across manydisciplines grid generation for practical reservoir modelingand simulation remains a daunting task
In typical structural modeling workflows the first taskis to build a fault network as a set of surfaces and contactsbetween these surfaces This step is itself decomposed intosurface fitting which creates one fault surface from eachfault interpretation and editing in which faults can beextended filtered and connected one to another based on
proximity and modelerrsquos interpretation Then horizons arebuilt from seismic picks conformably to the fault network[22] Fault modeling within Abu Madi reservoirs is a rea-sonably straightforward process since only two faults wereidentified during the seismic interpretation Potential synsed-imentary faults and slumps are apparent within the reservoirbut these were not modeled as they are small in scale andexhibit limited throwsThe faults are all normal displacementand were modeled using a network in which individualfault geometries were classified and their interaction definedGrid-building takes the fault model described above andconstructs a 3D grid within the framework of the reservoir-defining seismic surfaces Seismic surfaces representing topAbu Madi top level III main top level III lower andbottom Abu Madi were depth-converted as a part of theinterpretation process within Petrel software
The final result is a 3D geometric model of Abu Madireservoirs based on well and seismic data (Figure 17) andinvolves the construction of the modeling grid using aframework of seismic surfaces faults and stratigraphic wellties 3D geometric model of Abu Madi reservoirs shows thepromising pathway of the future development wells based onthe integration of seismic and well data in this study whichcoincides with the up-to-date locations of drilling wells inthe Baltim area and locates at the center of the Abu MadiPaleovalley (Figure 17)
5 Conclusions
In conclusion we have seen that the role of geometricmodeling is becoming more important for exploring reser-voir structures 3D geometric modeling provided a usefulmeans towards understanding the structure of Abu Madi
International Journal of Geophysics 11
reservoirs Baltim fields (South East and North) comprisetwo separate gas pools named ldquolevel III lowerrdquo and ldquolevelIII mainrdquo within the upper Messinian Abu Madi FormationThe trap is a structural-stratigraphic type with pinch-outagainst incised AbuMadi Paleovalley boundaries and is fault-bounded in the northern and southern part Identificationof stratigraphic architecture not only helps understand thegeological history but also has implications for hydrocarbonexploration as the confinement of flow in an incised valley hasgreat implications for channel amalgamation and producesfavorable reservoirs with potential two-way closure The AbuMadi reservoirs shape influences the seismic response ofthe incised Abu Madi Paleovalley making it necessary toaccount for 3D effects in order to obtain accurate resultsThe accuracy of the estimated thickness of each Abu Madireservoir is a critical element in assessment of reservesvolumes of hydrocarbons in place and production profilesThe promising locations of the future development wellsbased on the integration of seismic and well data coincidewith the up-to-date locations of drilling wells in the Baltimarea and locate at the center of the Abu Madi Paleovalley 3Dgeometricmodel of AbuMadi reservoir in Baltim area shouldbe kept in mind during future field development decisions
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
The authors wish to express their gratitude to Egyptian Gen-eral Petroleum Corporation (EGPC) and Belayim PetroleumCompany (PETROBEL) for providing the seismic lines welllogs and other relevant data Ministry of Higher Educationamp Scientific Research andMinistry of Petroleum in Egypt arealso acknowledged for promoting advancement in researchand establishing a possible future linkage between the indus-try and university They thank Schlumberger for furnishingthe Petrel software for the seismic interpretation
References
[1] S Dalla H Harsy andM Serazzi ldquoHydrocarbon exploration ina complex incised valley fill an example from the lateMessinianAbu Madi formation (Nile Delta Basin Egypt)rdquo The LeadingEdge vol 16 no 12 pp 1819ndash1826 1997
[2] Egyptian General Petroleum Cooperation (EGPC) Nile DeltaandNorth Sinai A Field Discoveries andHydrocarbon Potentials(A Comprehensive Overview) Egyptian General PetroleumCairo Egypt 1994
[3] M Alfy F Polo and M Shash ldquoThe geology of Abu Madigas fieldrdquo in Proceedings of the 11th Petroleum Exploration andProduction Conference pp 485ndash513 Cairo Egypt 1992
[4] I El Heiny R Rizk and M Hassan ldquoSedimentological modelfor AbuMadi sand reservoir AbuMadi field Nile Delta Egyptrdquoin Proceedings of the EGPC 10th Exploration and ProductionConference pp 1ndash38 Cairo Egypt 1990
[5] J D Pigott and M I Abdel-Fattah ldquoSeismic stratigraphy of theMessinian Nile Delta coastal plain recognition of the fluvial
Regressive Systems Tract and its potential for hydrocarbonexplorationrdquo Journal of African Earth Sciences vol 95 pp 9ndash212014
[6] R A Abu El-Ella ldquoTheNeogene-Quaternary section in theNileDelta Egypt geology and hydrocarbon potentialrdquo Journal ofPetroleum Geology vol 13 no 3 pp 329ndash340 1990
[7] J C Dolson M V Shann S Matbouly C Harwood R Rashedand H Hammouda ldquoThe petroleum potential of Egyptrdquo AAPGMemoir vol 74 pp 453ndash482 2001
[8] M I Abdel-Fattah and R M Slatt ldquoSequence stratigraphiccontrols on reservoir characterization and architecture casestudy of the Messinian Abu Madi incised-valley fill EgyptrdquoCentral European Journal of Geosciences vol 5 no 4 pp 497ndash507 2013
[9] J Harms and J Wray ldquoNile Deltardquo in Geology of Egypt R SaidEd pp 329ndash343 A A Balkema Rotterdam The Netherlands1990
[10] M H Mohamed Evaluation of hydrocarbon potentiality ofMiocene rocks in the Northern portion of Abu Madi Paleovalleyoffshore Mediterranean Sea Egypt [MS thesis] Faculty ofScience Suez Canal University 2012
[11] M I Abdel-Fattah ldquoPetrophysical characteristics of the mes-sinian abu madi formation in the baltim east and north fieldsoffshore Nile delta Egyptrdquo Journal of PetroleumGeology vol 37no 2 pp 183ndash195 2014
[12] A Rizzini F Vezzani V Cococcetta and G Milad ldquoStratigra-phy and sedimentation of a Neogene-Quaternary section in theNile Delta area (ARE)rdquo Marine Geology vol 27 no 3-4 pp327ndash348 1978
[13] M Bacon R Simm and T Redshaw 3-D Seismic InterpretationCambridge University Press New York NY USA 2003
[14] M E Badley Practical Seismic Interpretation InternationalHuman Resources Development Corporation Boston MassUSA 1985
[15] M B Dobrin and C H Savit Introduction to GeophysicalProspecting McGraw-Hill New York NY USA 4th edition1988
[16] O L Anderson and J D Pigott ldquoSeismic technology and lawpartners or adversariesrdquo Energy and Mineral Law Institute vol24 2004
[17] A R Brown Interpretation of Three-Dimensional Seismic DataAmerican Association of Petroleum Geologists and the Societyof Exploration Geophysicists 6th edition 2004
[18] O Catuneanu ldquoSequence stratigraphy of clastic systems con-cepts merits and pitfallsrdquo Journal of African Earth Sciences vol35 no 1 pp 1ndash43 2002
[19] O Catuneanu V Abreu J P Bhattacharya et al ldquoTowardsthe standardization of sequence stratigraphyrdquo Earth-ScienceReviews vol 92 pp 1ndash33 2009
[20] A M Salem J M Ketzer S Morad R R Rizk and I S Al-Aasm ldquoDiagenesis and reservoir-quality evolution of incised-valley sandstone evidence from the Abu Madi gas reservoirs(upper Miocene) the Nile Delta Basin Egyptrdquo Journal ofSedimentary Research vol 75 no 4 pp 572ndash584 2005
[21] L V Branets S S Ghai S L Lyons and X-H Wu ldquoChallengesand technologies in reservoir modelingrdquo Communications inComputational Physics vol 6 no 1 pp 1ndash23 2009
[22] G Caumon G Laurent N Cherpeau et al ldquoStructural frame-work and reservoir gridding current bottlenecks and wayforwardrdquo in Proceedings of the GUSSOWGeoscience Conferencep 8 Banff Canada 2011
Figure 13 Time and depth structure map of bottom Abu Madi Formation
150
150
150
BE1
BE2
BE4
BE9
BS
BN1BN2
BNE1
000
6000
12000
18000
24000
Thic
knes
s (m
)
1000
1004
1008
1012
1016
1020
1024
1028
1032
1000
1004
1008
1012
1016
1020
1024
1028
1032
times103 times103
620000 628000 636000 644000
620000 628000 636000 644000
CI = 30m
0 2 4 6 8 10(km)
N
Figure 14 Thickness map of level III main
The area was dissected by two main faults (Figure 6)the first one is a great high angle E-W normal fault dippingnorthward in the southern part of Baltim area betweenBaltimSouth andBaltimEast fieldsThe second fault between BaltimNorth and Baltim Northeast fields which are in NE-SWdirection dips to the north and displaces all the levels morethan 80mThe time and depthmaps of all horizons show thatthere is a dipping toward the north of the study area as thetime and depth values increase toward the north (Figures 10to 13)
42 Isochore Maps Two isochore thickness maps were con-structed for the two pay zones ldquolevel III lowerrdquo and ldquolevelIII mainrdquo Uncertainties affect these elements throughoutthe entire interpretation process They have some bearingon the geometric shape and subsequently on the grossreservoir volume (GRV) of the Baltim fields The increaseof the gross reservoir volume (GRV) leads subsequently to
0
0 00
0
0
0
00
0
00
0 0
150 150150
BE1
BE2
BE9
BN1BN2
BNE1
BS
6000
12000
18000
24000N
1000
1004
1008
1012
1016
1020
1024
1028
1032
times103
1000
1004
1008
1012
1016
1020
1024
1028
1032
times103
620000 628000 636000 644000
620000 628000 636000 644000
CI = 30m
0 2 4 6 8 10(km)
Thic
knes
s (m
)
minus000
0
BE4
Figure 15 Thickness map of level III lower
the increase of the net pay thickness volumes of hydrocar-bons in place reserves and production profiles For level IIImain the thickness varies between 0 and 190m (Figure 14)while for level III lower the thickness varies between 0and 210m (Figure 15) These two isochore maps show thatreservoir thickness of both level III main and lower increaseat the center of the Abu Madi Paleovalley and pinch-outand decrease toward the boundaries where the minimumthickness values were observed Thus the assessment ofgeometrical uncertainties is an essential first step in a fieldstudy for evaluation development or optimization purposes
43 Geological Model A simplified fluvial sequence strati-graphic model of the Late Messinian Abu Madi Formationis shown in Figure 16 This architecture forms the basicconceptual model of the AbuMadi reservoirs ldquolevel III mainrdquoand ldquolevel III lowerrdquo used for well correlation and seismic
Figure 16 Stratigraphic architecture of a fluvial depositional sequence influenced by base-level fluctuations for the Abu Madi incisedvalley channel system Each system tract contains a fining upward succession caused by the continuous coastal aggradation and subsequentshallowing of the fluvial graded profile List of abbreviations lowstand system tract (LST) transgressive system tract (TST) highstand systemtract (HST) maximum flooding surface (MFS) and sequence boundary (SB)
interpretation The spatial and temporal relation betweenbraided and meandering river systems is illustrated for asingle base-level cycle At the beginning of the lowstandsystem tract (LST) braided systems develop close to thesource area where the slope is generally steeper sedimentcoarser channels are overloaded and accommodation islow Towards the coastal plain as the fluvial slope becomesflatter meandering systems take over Rivers here carryless sediment are underloaded and therefore usually havesingle channels As their sinuosity increases the stresses onthe banks raise the probability of bank undermining out-of-channel flow and overbank escape of sediments Thismeandering system eventually grades into the estuary or deltafront systemsAlso due to the overall rise andflattening of thefluvial gradients the entire cycle has a fining upward tendencyBut due to the interaction between sediment supply and therate of accommodation creation at the shoreline the entiresystem progrades or retrogrades during the three stages ofbase-level rise Furthermore two sudden facies shifts may bepresent during the base-level rise cycle
As apparent from Figure 16 transgressions in fluvial sys-temsmay cause estuarine or lagoonal deposits butmore oftenthey are associated with a higher occurrence of floodplaindeposits when a marine influence remains restricted to
areas further basinwards Floodplain deposits are hardly evercontinuous over large areas due to avulsions and channelmigrations [18ndash20] Also overbank deposits and crevassesplays may hinder successful floodplain identification It istherefore often difficult and unreliable to correlate fluvialsequences based on maximum flooding surface (MFS) Thisopposed to the marine realm where the MFS is often betterdeveloped than the sequence boundary (SB) simply due tothe fact that subaerial erosion does not extend below the sealevel In fluvial settings the development of erosional surfacescan be highly heterogeneous due to incisions but theirpreservation potential is much higher due to the increasingaccommodation following the base-level lowstand This incontrast to the MFS which is trailed by a usually thinsand layer developed the highstand system tract (HST) andsubsequent base-level fall It is therefore a common practiceto correlate fluvial succession based on SBs and devise asequence stratigraphic framework in accordance with this
44 3D Geometric Modeling Reservoir modeling is playingan increasingly important role in developing and producinghydrocarbon reserves Various technologies used to under-stand a prospective reservoir provide information at manydifferent scales Core plugs are a few inches in size Well
10 International Journal of Geophysics
Elev
atio
n de
pth
(m)
BS
BE3
BE8BE9
BE5BN2BNE1
BN5BN1
BE2BE10
BE7BE4BE1
minus4100
minus4000
minus3900
minus3800
minus3700
minus3600
minus3500
minus3400
Figure 17 3D geometric model of Abu Madi reservoirs showing the promising pathway (red dashed line) of the future development wellswhich coincides with the up-to-date locations of drilling wells in the Baltim area
logs can detect properties within a few feet around thewell Seismic imaging covers a huge volume but its typicalresolution is limited to a few meters vertically and tensof meters horizontally [21] Limited by time and capitaldirect sampling of reservoir rock and fluid properties issparse Therefore geologic interpretations based on seismicinformation and understandings of sedimentary processesare used to interpolate or extrapolate the measured datain order to yield complete reservoir geometry descriptionsInformation provided by these technologies is incorporatedinto reservoir models Constructing reservoir models hasbecome a crucial step in resource development as reservoirmodeling provides a venue to integrate and reconcile allavailable data and geologic concepts [21]
One of the key challenges in reservoir modeling isaccurate representation of reservoir geometry includingthe structural framework (ie horizonsmajor depositionalsurfaces that are nearly horizontal and fault surfaces whichcan have arbitrary spatial size and orientation) and detailedstratigraphic layers (Figure 17) The structural frameworksdelineate major compartments of a reservoir and oftenprovide the first order controls on in-place fluid volumesand fluid movement during productionThus it is importantto model the structural frameworks accurately Howeverdespite decades of advances in grid generation across manydisciplines grid generation for practical reservoir modelingand simulation remains a daunting task
In typical structural modeling workflows the first taskis to build a fault network as a set of surfaces and contactsbetween these surfaces This step is itself decomposed intosurface fitting which creates one fault surface from eachfault interpretation and editing in which faults can beextended filtered and connected one to another based on
proximity and modelerrsquos interpretation Then horizons arebuilt from seismic picks conformably to the fault network[22] Fault modeling within Abu Madi reservoirs is a rea-sonably straightforward process since only two faults wereidentified during the seismic interpretation Potential synsed-imentary faults and slumps are apparent within the reservoirbut these were not modeled as they are small in scale andexhibit limited throwsThe faults are all normal displacementand were modeled using a network in which individualfault geometries were classified and their interaction definedGrid-building takes the fault model described above andconstructs a 3D grid within the framework of the reservoir-defining seismic surfaces Seismic surfaces representing topAbu Madi top level III main top level III lower andbottom Abu Madi were depth-converted as a part of theinterpretation process within Petrel software
The final result is a 3D geometric model of Abu Madireservoirs based on well and seismic data (Figure 17) andinvolves the construction of the modeling grid using aframework of seismic surfaces faults and stratigraphic wellties 3D geometric model of Abu Madi reservoirs shows thepromising pathway of the future development wells based onthe integration of seismic and well data in this study whichcoincides with the up-to-date locations of drilling wells inthe Baltim area and locates at the center of the Abu MadiPaleovalley (Figure 17)
5 Conclusions
In conclusion we have seen that the role of geometricmodeling is becoming more important for exploring reser-voir structures 3D geometric modeling provided a usefulmeans towards understanding the structure of Abu Madi
International Journal of Geophysics 11
reservoirs Baltim fields (South East and North) comprisetwo separate gas pools named ldquolevel III lowerrdquo and ldquolevelIII mainrdquo within the upper Messinian Abu Madi FormationThe trap is a structural-stratigraphic type with pinch-outagainst incised AbuMadi Paleovalley boundaries and is fault-bounded in the northern and southern part Identificationof stratigraphic architecture not only helps understand thegeological history but also has implications for hydrocarbonexploration as the confinement of flow in an incised valley hasgreat implications for channel amalgamation and producesfavorable reservoirs with potential two-way closure The AbuMadi reservoirs shape influences the seismic response ofthe incised Abu Madi Paleovalley making it necessary toaccount for 3D effects in order to obtain accurate resultsThe accuracy of the estimated thickness of each Abu Madireservoir is a critical element in assessment of reservesvolumes of hydrocarbons in place and production profilesThe promising locations of the future development wellsbased on the integration of seismic and well data coincidewith the up-to-date locations of drilling wells in the Baltimarea and locate at the center of the Abu Madi Paleovalley 3Dgeometricmodel of AbuMadi reservoir in Baltim area shouldbe kept in mind during future field development decisions
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
The authors wish to express their gratitude to Egyptian Gen-eral Petroleum Corporation (EGPC) and Belayim PetroleumCompany (PETROBEL) for providing the seismic lines welllogs and other relevant data Ministry of Higher Educationamp Scientific Research andMinistry of Petroleum in Egypt arealso acknowledged for promoting advancement in researchand establishing a possible future linkage between the indus-try and university They thank Schlumberger for furnishingthe Petrel software for the seismic interpretation
References
[1] S Dalla H Harsy andM Serazzi ldquoHydrocarbon exploration ina complex incised valley fill an example from the lateMessinianAbu Madi formation (Nile Delta Basin Egypt)rdquo The LeadingEdge vol 16 no 12 pp 1819ndash1826 1997
[2] Egyptian General Petroleum Cooperation (EGPC) Nile DeltaandNorth Sinai A Field Discoveries andHydrocarbon Potentials(A Comprehensive Overview) Egyptian General PetroleumCairo Egypt 1994
[3] M Alfy F Polo and M Shash ldquoThe geology of Abu Madigas fieldrdquo in Proceedings of the 11th Petroleum Exploration andProduction Conference pp 485ndash513 Cairo Egypt 1992
[4] I El Heiny R Rizk and M Hassan ldquoSedimentological modelfor AbuMadi sand reservoir AbuMadi field Nile Delta Egyptrdquoin Proceedings of the EGPC 10th Exploration and ProductionConference pp 1ndash38 Cairo Egypt 1990
[5] J D Pigott and M I Abdel-Fattah ldquoSeismic stratigraphy of theMessinian Nile Delta coastal plain recognition of the fluvial
Regressive Systems Tract and its potential for hydrocarbonexplorationrdquo Journal of African Earth Sciences vol 95 pp 9ndash212014
[6] R A Abu El-Ella ldquoTheNeogene-Quaternary section in theNileDelta Egypt geology and hydrocarbon potentialrdquo Journal ofPetroleum Geology vol 13 no 3 pp 329ndash340 1990
[7] J C Dolson M V Shann S Matbouly C Harwood R Rashedand H Hammouda ldquoThe petroleum potential of Egyptrdquo AAPGMemoir vol 74 pp 453ndash482 2001
[8] M I Abdel-Fattah and R M Slatt ldquoSequence stratigraphiccontrols on reservoir characterization and architecture casestudy of the Messinian Abu Madi incised-valley fill EgyptrdquoCentral European Journal of Geosciences vol 5 no 4 pp 497ndash507 2013
[9] J Harms and J Wray ldquoNile Deltardquo in Geology of Egypt R SaidEd pp 329ndash343 A A Balkema Rotterdam The Netherlands1990
[10] M H Mohamed Evaluation of hydrocarbon potentiality ofMiocene rocks in the Northern portion of Abu Madi Paleovalleyoffshore Mediterranean Sea Egypt [MS thesis] Faculty ofScience Suez Canal University 2012
[11] M I Abdel-Fattah ldquoPetrophysical characteristics of the mes-sinian abu madi formation in the baltim east and north fieldsoffshore Nile delta Egyptrdquo Journal of PetroleumGeology vol 37no 2 pp 183ndash195 2014
[12] A Rizzini F Vezzani V Cococcetta and G Milad ldquoStratigra-phy and sedimentation of a Neogene-Quaternary section in theNile Delta area (ARE)rdquo Marine Geology vol 27 no 3-4 pp327ndash348 1978
[13] M Bacon R Simm and T Redshaw 3-D Seismic InterpretationCambridge University Press New York NY USA 2003
[14] M E Badley Practical Seismic Interpretation InternationalHuman Resources Development Corporation Boston MassUSA 1985
[15] M B Dobrin and C H Savit Introduction to GeophysicalProspecting McGraw-Hill New York NY USA 4th edition1988
[16] O L Anderson and J D Pigott ldquoSeismic technology and lawpartners or adversariesrdquo Energy and Mineral Law Institute vol24 2004
[17] A R Brown Interpretation of Three-Dimensional Seismic DataAmerican Association of Petroleum Geologists and the Societyof Exploration Geophysicists 6th edition 2004
[18] O Catuneanu ldquoSequence stratigraphy of clastic systems con-cepts merits and pitfallsrdquo Journal of African Earth Sciences vol35 no 1 pp 1ndash43 2002
[19] O Catuneanu V Abreu J P Bhattacharya et al ldquoTowardsthe standardization of sequence stratigraphyrdquo Earth-ScienceReviews vol 92 pp 1ndash33 2009
[20] A M Salem J M Ketzer S Morad R R Rizk and I S Al-Aasm ldquoDiagenesis and reservoir-quality evolution of incised-valley sandstone evidence from the Abu Madi gas reservoirs(upper Miocene) the Nile Delta Basin Egyptrdquo Journal ofSedimentary Research vol 75 no 4 pp 572ndash584 2005
[21] L V Branets S S Ghai S L Lyons and X-H Wu ldquoChallengesand technologies in reservoir modelingrdquo Communications inComputational Physics vol 6 no 1 pp 1ndash23 2009
[22] G Caumon G Laurent N Cherpeau et al ldquoStructural frame-work and reservoir gridding current bottlenecks and wayforwardrdquo in Proceedings of the GUSSOWGeoscience Conferencep 8 Banff Canada 2011
Figure 16 Stratigraphic architecture of a fluvial depositional sequence influenced by base-level fluctuations for the Abu Madi incisedvalley channel system Each system tract contains a fining upward succession caused by the continuous coastal aggradation and subsequentshallowing of the fluvial graded profile List of abbreviations lowstand system tract (LST) transgressive system tract (TST) highstand systemtract (HST) maximum flooding surface (MFS) and sequence boundary (SB)
interpretation The spatial and temporal relation betweenbraided and meandering river systems is illustrated for asingle base-level cycle At the beginning of the lowstandsystem tract (LST) braided systems develop close to thesource area where the slope is generally steeper sedimentcoarser channels are overloaded and accommodation islow Towards the coastal plain as the fluvial slope becomesflatter meandering systems take over Rivers here carryless sediment are underloaded and therefore usually havesingle channels As their sinuosity increases the stresses onthe banks raise the probability of bank undermining out-of-channel flow and overbank escape of sediments Thismeandering system eventually grades into the estuary or deltafront systemsAlso due to the overall rise andflattening of thefluvial gradients the entire cycle has a fining upward tendencyBut due to the interaction between sediment supply and therate of accommodation creation at the shoreline the entiresystem progrades or retrogrades during the three stages ofbase-level rise Furthermore two sudden facies shifts may bepresent during the base-level rise cycle
As apparent from Figure 16 transgressions in fluvial sys-temsmay cause estuarine or lagoonal deposits butmore oftenthey are associated with a higher occurrence of floodplaindeposits when a marine influence remains restricted to
areas further basinwards Floodplain deposits are hardly evercontinuous over large areas due to avulsions and channelmigrations [18ndash20] Also overbank deposits and crevassesplays may hinder successful floodplain identification It istherefore often difficult and unreliable to correlate fluvialsequences based on maximum flooding surface (MFS) Thisopposed to the marine realm where the MFS is often betterdeveloped than the sequence boundary (SB) simply due tothe fact that subaerial erosion does not extend below the sealevel In fluvial settings the development of erosional surfacescan be highly heterogeneous due to incisions but theirpreservation potential is much higher due to the increasingaccommodation following the base-level lowstand This incontrast to the MFS which is trailed by a usually thinsand layer developed the highstand system tract (HST) andsubsequent base-level fall It is therefore a common practiceto correlate fluvial succession based on SBs and devise asequence stratigraphic framework in accordance with this
44 3D Geometric Modeling Reservoir modeling is playingan increasingly important role in developing and producinghydrocarbon reserves Various technologies used to under-stand a prospective reservoir provide information at manydifferent scales Core plugs are a few inches in size Well
10 International Journal of Geophysics
Elev
atio
n de
pth
(m)
BS
BE3
BE8BE9
BE5BN2BNE1
BN5BN1
BE2BE10
BE7BE4BE1
minus4100
minus4000
minus3900
minus3800
minus3700
minus3600
minus3500
minus3400
Figure 17 3D geometric model of Abu Madi reservoirs showing the promising pathway (red dashed line) of the future development wellswhich coincides with the up-to-date locations of drilling wells in the Baltim area
logs can detect properties within a few feet around thewell Seismic imaging covers a huge volume but its typicalresolution is limited to a few meters vertically and tensof meters horizontally [21] Limited by time and capitaldirect sampling of reservoir rock and fluid properties issparse Therefore geologic interpretations based on seismicinformation and understandings of sedimentary processesare used to interpolate or extrapolate the measured datain order to yield complete reservoir geometry descriptionsInformation provided by these technologies is incorporatedinto reservoir models Constructing reservoir models hasbecome a crucial step in resource development as reservoirmodeling provides a venue to integrate and reconcile allavailable data and geologic concepts [21]
One of the key challenges in reservoir modeling isaccurate representation of reservoir geometry includingthe structural framework (ie horizonsmajor depositionalsurfaces that are nearly horizontal and fault surfaces whichcan have arbitrary spatial size and orientation) and detailedstratigraphic layers (Figure 17) The structural frameworksdelineate major compartments of a reservoir and oftenprovide the first order controls on in-place fluid volumesand fluid movement during productionThus it is importantto model the structural frameworks accurately Howeverdespite decades of advances in grid generation across manydisciplines grid generation for practical reservoir modelingand simulation remains a daunting task
In typical structural modeling workflows the first taskis to build a fault network as a set of surfaces and contactsbetween these surfaces This step is itself decomposed intosurface fitting which creates one fault surface from eachfault interpretation and editing in which faults can beextended filtered and connected one to another based on
proximity and modelerrsquos interpretation Then horizons arebuilt from seismic picks conformably to the fault network[22] Fault modeling within Abu Madi reservoirs is a rea-sonably straightforward process since only two faults wereidentified during the seismic interpretation Potential synsed-imentary faults and slumps are apparent within the reservoirbut these were not modeled as they are small in scale andexhibit limited throwsThe faults are all normal displacementand were modeled using a network in which individualfault geometries were classified and their interaction definedGrid-building takes the fault model described above andconstructs a 3D grid within the framework of the reservoir-defining seismic surfaces Seismic surfaces representing topAbu Madi top level III main top level III lower andbottom Abu Madi were depth-converted as a part of theinterpretation process within Petrel software
The final result is a 3D geometric model of Abu Madireservoirs based on well and seismic data (Figure 17) andinvolves the construction of the modeling grid using aframework of seismic surfaces faults and stratigraphic wellties 3D geometric model of Abu Madi reservoirs shows thepromising pathway of the future development wells based onthe integration of seismic and well data in this study whichcoincides with the up-to-date locations of drilling wells inthe Baltim area and locates at the center of the Abu MadiPaleovalley (Figure 17)
5 Conclusions
In conclusion we have seen that the role of geometricmodeling is becoming more important for exploring reser-voir structures 3D geometric modeling provided a usefulmeans towards understanding the structure of Abu Madi
International Journal of Geophysics 11
reservoirs Baltim fields (South East and North) comprisetwo separate gas pools named ldquolevel III lowerrdquo and ldquolevelIII mainrdquo within the upper Messinian Abu Madi FormationThe trap is a structural-stratigraphic type with pinch-outagainst incised AbuMadi Paleovalley boundaries and is fault-bounded in the northern and southern part Identificationof stratigraphic architecture not only helps understand thegeological history but also has implications for hydrocarbonexploration as the confinement of flow in an incised valley hasgreat implications for channel amalgamation and producesfavorable reservoirs with potential two-way closure The AbuMadi reservoirs shape influences the seismic response ofthe incised Abu Madi Paleovalley making it necessary toaccount for 3D effects in order to obtain accurate resultsThe accuracy of the estimated thickness of each Abu Madireservoir is a critical element in assessment of reservesvolumes of hydrocarbons in place and production profilesThe promising locations of the future development wellsbased on the integration of seismic and well data coincidewith the up-to-date locations of drilling wells in the Baltimarea and locate at the center of the Abu Madi Paleovalley 3Dgeometricmodel of AbuMadi reservoir in Baltim area shouldbe kept in mind during future field development decisions
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
The authors wish to express their gratitude to Egyptian Gen-eral Petroleum Corporation (EGPC) and Belayim PetroleumCompany (PETROBEL) for providing the seismic lines welllogs and other relevant data Ministry of Higher Educationamp Scientific Research andMinistry of Petroleum in Egypt arealso acknowledged for promoting advancement in researchand establishing a possible future linkage between the indus-try and university They thank Schlumberger for furnishingthe Petrel software for the seismic interpretation
References
[1] S Dalla H Harsy andM Serazzi ldquoHydrocarbon exploration ina complex incised valley fill an example from the lateMessinianAbu Madi formation (Nile Delta Basin Egypt)rdquo The LeadingEdge vol 16 no 12 pp 1819ndash1826 1997
[2] Egyptian General Petroleum Cooperation (EGPC) Nile DeltaandNorth Sinai A Field Discoveries andHydrocarbon Potentials(A Comprehensive Overview) Egyptian General PetroleumCairo Egypt 1994
[3] M Alfy F Polo and M Shash ldquoThe geology of Abu Madigas fieldrdquo in Proceedings of the 11th Petroleum Exploration andProduction Conference pp 485ndash513 Cairo Egypt 1992
[4] I El Heiny R Rizk and M Hassan ldquoSedimentological modelfor AbuMadi sand reservoir AbuMadi field Nile Delta Egyptrdquoin Proceedings of the EGPC 10th Exploration and ProductionConference pp 1ndash38 Cairo Egypt 1990
[5] J D Pigott and M I Abdel-Fattah ldquoSeismic stratigraphy of theMessinian Nile Delta coastal plain recognition of the fluvial
Regressive Systems Tract and its potential for hydrocarbonexplorationrdquo Journal of African Earth Sciences vol 95 pp 9ndash212014
[6] R A Abu El-Ella ldquoTheNeogene-Quaternary section in theNileDelta Egypt geology and hydrocarbon potentialrdquo Journal ofPetroleum Geology vol 13 no 3 pp 329ndash340 1990
[7] J C Dolson M V Shann S Matbouly C Harwood R Rashedand H Hammouda ldquoThe petroleum potential of Egyptrdquo AAPGMemoir vol 74 pp 453ndash482 2001
[8] M I Abdel-Fattah and R M Slatt ldquoSequence stratigraphiccontrols on reservoir characterization and architecture casestudy of the Messinian Abu Madi incised-valley fill EgyptrdquoCentral European Journal of Geosciences vol 5 no 4 pp 497ndash507 2013
[9] J Harms and J Wray ldquoNile Deltardquo in Geology of Egypt R SaidEd pp 329ndash343 A A Balkema Rotterdam The Netherlands1990
[10] M H Mohamed Evaluation of hydrocarbon potentiality ofMiocene rocks in the Northern portion of Abu Madi Paleovalleyoffshore Mediterranean Sea Egypt [MS thesis] Faculty ofScience Suez Canal University 2012
[11] M I Abdel-Fattah ldquoPetrophysical characteristics of the mes-sinian abu madi formation in the baltim east and north fieldsoffshore Nile delta Egyptrdquo Journal of PetroleumGeology vol 37no 2 pp 183ndash195 2014
[12] A Rizzini F Vezzani V Cococcetta and G Milad ldquoStratigra-phy and sedimentation of a Neogene-Quaternary section in theNile Delta area (ARE)rdquo Marine Geology vol 27 no 3-4 pp327ndash348 1978
[13] M Bacon R Simm and T Redshaw 3-D Seismic InterpretationCambridge University Press New York NY USA 2003
[14] M E Badley Practical Seismic Interpretation InternationalHuman Resources Development Corporation Boston MassUSA 1985
[15] M B Dobrin and C H Savit Introduction to GeophysicalProspecting McGraw-Hill New York NY USA 4th edition1988
[16] O L Anderson and J D Pigott ldquoSeismic technology and lawpartners or adversariesrdquo Energy and Mineral Law Institute vol24 2004
[17] A R Brown Interpretation of Three-Dimensional Seismic DataAmerican Association of Petroleum Geologists and the Societyof Exploration Geophysicists 6th edition 2004
[18] O Catuneanu ldquoSequence stratigraphy of clastic systems con-cepts merits and pitfallsrdquo Journal of African Earth Sciences vol35 no 1 pp 1ndash43 2002
[19] O Catuneanu V Abreu J P Bhattacharya et al ldquoTowardsthe standardization of sequence stratigraphyrdquo Earth-ScienceReviews vol 92 pp 1ndash33 2009
[20] A M Salem J M Ketzer S Morad R R Rizk and I S Al-Aasm ldquoDiagenesis and reservoir-quality evolution of incised-valley sandstone evidence from the Abu Madi gas reservoirs(upper Miocene) the Nile Delta Basin Egyptrdquo Journal ofSedimentary Research vol 75 no 4 pp 572ndash584 2005
[21] L V Branets S S Ghai S L Lyons and X-H Wu ldquoChallengesand technologies in reservoir modelingrdquo Communications inComputational Physics vol 6 no 1 pp 1ndash23 2009
[22] G Caumon G Laurent N Cherpeau et al ldquoStructural frame-work and reservoir gridding current bottlenecks and wayforwardrdquo in Proceedings of the GUSSOWGeoscience Conferencep 8 Banff Canada 2011
Figure 17 3D geometric model of Abu Madi reservoirs showing the promising pathway (red dashed line) of the future development wellswhich coincides with the up-to-date locations of drilling wells in the Baltim area
logs can detect properties within a few feet around thewell Seismic imaging covers a huge volume but its typicalresolution is limited to a few meters vertically and tensof meters horizontally [21] Limited by time and capitaldirect sampling of reservoir rock and fluid properties issparse Therefore geologic interpretations based on seismicinformation and understandings of sedimentary processesare used to interpolate or extrapolate the measured datain order to yield complete reservoir geometry descriptionsInformation provided by these technologies is incorporatedinto reservoir models Constructing reservoir models hasbecome a crucial step in resource development as reservoirmodeling provides a venue to integrate and reconcile allavailable data and geologic concepts [21]
One of the key challenges in reservoir modeling isaccurate representation of reservoir geometry includingthe structural framework (ie horizonsmajor depositionalsurfaces that are nearly horizontal and fault surfaces whichcan have arbitrary spatial size and orientation) and detailedstratigraphic layers (Figure 17) The structural frameworksdelineate major compartments of a reservoir and oftenprovide the first order controls on in-place fluid volumesand fluid movement during productionThus it is importantto model the structural frameworks accurately Howeverdespite decades of advances in grid generation across manydisciplines grid generation for practical reservoir modelingand simulation remains a daunting task
In typical structural modeling workflows the first taskis to build a fault network as a set of surfaces and contactsbetween these surfaces This step is itself decomposed intosurface fitting which creates one fault surface from eachfault interpretation and editing in which faults can beextended filtered and connected one to another based on
proximity and modelerrsquos interpretation Then horizons arebuilt from seismic picks conformably to the fault network[22] Fault modeling within Abu Madi reservoirs is a rea-sonably straightforward process since only two faults wereidentified during the seismic interpretation Potential synsed-imentary faults and slumps are apparent within the reservoirbut these were not modeled as they are small in scale andexhibit limited throwsThe faults are all normal displacementand were modeled using a network in which individualfault geometries were classified and their interaction definedGrid-building takes the fault model described above andconstructs a 3D grid within the framework of the reservoir-defining seismic surfaces Seismic surfaces representing topAbu Madi top level III main top level III lower andbottom Abu Madi were depth-converted as a part of theinterpretation process within Petrel software
The final result is a 3D geometric model of Abu Madireservoirs based on well and seismic data (Figure 17) andinvolves the construction of the modeling grid using aframework of seismic surfaces faults and stratigraphic wellties 3D geometric model of Abu Madi reservoirs shows thepromising pathway of the future development wells based onthe integration of seismic and well data in this study whichcoincides with the up-to-date locations of drilling wells inthe Baltim area and locates at the center of the Abu MadiPaleovalley (Figure 17)
5 Conclusions
In conclusion we have seen that the role of geometricmodeling is becoming more important for exploring reser-voir structures 3D geometric modeling provided a usefulmeans towards understanding the structure of Abu Madi
International Journal of Geophysics 11
reservoirs Baltim fields (South East and North) comprisetwo separate gas pools named ldquolevel III lowerrdquo and ldquolevelIII mainrdquo within the upper Messinian Abu Madi FormationThe trap is a structural-stratigraphic type with pinch-outagainst incised AbuMadi Paleovalley boundaries and is fault-bounded in the northern and southern part Identificationof stratigraphic architecture not only helps understand thegeological history but also has implications for hydrocarbonexploration as the confinement of flow in an incised valley hasgreat implications for channel amalgamation and producesfavorable reservoirs with potential two-way closure The AbuMadi reservoirs shape influences the seismic response ofthe incised Abu Madi Paleovalley making it necessary toaccount for 3D effects in order to obtain accurate resultsThe accuracy of the estimated thickness of each Abu Madireservoir is a critical element in assessment of reservesvolumes of hydrocarbons in place and production profilesThe promising locations of the future development wellsbased on the integration of seismic and well data coincidewith the up-to-date locations of drilling wells in the Baltimarea and locate at the center of the Abu Madi Paleovalley 3Dgeometricmodel of AbuMadi reservoir in Baltim area shouldbe kept in mind during future field development decisions
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
The authors wish to express their gratitude to Egyptian Gen-eral Petroleum Corporation (EGPC) and Belayim PetroleumCompany (PETROBEL) for providing the seismic lines welllogs and other relevant data Ministry of Higher Educationamp Scientific Research andMinistry of Petroleum in Egypt arealso acknowledged for promoting advancement in researchand establishing a possible future linkage between the indus-try and university They thank Schlumberger for furnishingthe Petrel software for the seismic interpretation
References
[1] S Dalla H Harsy andM Serazzi ldquoHydrocarbon exploration ina complex incised valley fill an example from the lateMessinianAbu Madi formation (Nile Delta Basin Egypt)rdquo The LeadingEdge vol 16 no 12 pp 1819ndash1826 1997
[2] Egyptian General Petroleum Cooperation (EGPC) Nile DeltaandNorth Sinai A Field Discoveries andHydrocarbon Potentials(A Comprehensive Overview) Egyptian General PetroleumCairo Egypt 1994
[3] M Alfy F Polo and M Shash ldquoThe geology of Abu Madigas fieldrdquo in Proceedings of the 11th Petroleum Exploration andProduction Conference pp 485ndash513 Cairo Egypt 1992
[4] I El Heiny R Rizk and M Hassan ldquoSedimentological modelfor AbuMadi sand reservoir AbuMadi field Nile Delta Egyptrdquoin Proceedings of the EGPC 10th Exploration and ProductionConference pp 1ndash38 Cairo Egypt 1990
[5] J D Pigott and M I Abdel-Fattah ldquoSeismic stratigraphy of theMessinian Nile Delta coastal plain recognition of the fluvial
Regressive Systems Tract and its potential for hydrocarbonexplorationrdquo Journal of African Earth Sciences vol 95 pp 9ndash212014
[6] R A Abu El-Ella ldquoTheNeogene-Quaternary section in theNileDelta Egypt geology and hydrocarbon potentialrdquo Journal ofPetroleum Geology vol 13 no 3 pp 329ndash340 1990
[7] J C Dolson M V Shann S Matbouly C Harwood R Rashedand H Hammouda ldquoThe petroleum potential of Egyptrdquo AAPGMemoir vol 74 pp 453ndash482 2001
[8] M I Abdel-Fattah and R M Slatt ldquoSequence stratigraphiccontrols on reservoir characterization and architecture casestudy of the Messinian Abu Madi incised-valley fill EgyptrdquoCentral European Journal of Geosciences vol 5 no 4 pp 497ndash507 2013
[9] J Harms and J Wray ldquoNile Deltardquo in Geology of Egypt R SaidEd pp 329ndash343 A A Balkema Rotterdam The Netherlands1990
[10] M H Mohamed Evaluation of hydrocarbon potentiality ofMiocene rocks in the Northern portion of Abu Madi Paleovalleyoffshore Mediterranean Sea Egypt [MS thesis] Faculty ofScience Suez Canal University 2012
[11] M I Abdel-Fattah ldquoPetrophysical characteristics of the mes-sinian abu madi formation in the baltim east and north fieldsoffshore Nile delta Egyptrdquo Journal of PetroleumGeology vol 37no 2 pp 183ndash195 2014
[12] A Rizzini F Vezzani V Cococcetta and G Milad ldquoStratigra-phy and sedimentation of a Neogene-Quaternary section in theNile Delta area (ARE)rdquo Marine Geology vol 27 no 3-4 pp327ndash348 1978
[13] M Bacon R Simm and T Redshaw 3-D Seismic InterpretationCambridge University Press New York NY USA 2003
[14] M E Badley Practical Seismic Interpretation InternationalHuman Resources Development Corporation Boston MassUSA 1985
[15] M B Dobrin and C H Savit Introduction to GeophysicalProspecting McGraw-Hill New York NY USA 4th edition1988
[16] O L Anderson and J D Pigott ldquoSeismic technology and lawpartners or adversariesrdquo Energy and Mineral Law Institute vol24 2004
[17] A R Brown Interpretation of Three-Dimensional Seismic DataAmerican Association of Petroleum Geologists and the Societyof Exploration Geophysicists 6th edition 2004
[18] O Catuneanu ldquoSequence stratigraphy of clastic systems con-cepts merits and pitfallsrdquo Journal of African Earth Sciences vol35 no 1 pp 1ndash43 2002
[19] O Catuneanu V Abreu J P Bhattacharya et al ldquoTowardsthe standardization of sequence stratigraphyrdquo Earth-ScienceReviews vol 92 pp 1ndash33 2009
[20] A M Salem J M Ketzer S Morad R R Rizk and I S Al-Aasm ldquoDiagenesis and reservoir-quality evolution of incised-valley sandstone evidence from the Abu Madi gas reservoirs(upper Miocene) the Nile Delta Basin Egyptrdquo Journal ofSedimentary Research vol 75 no 4 pp 572ndash584 2005
[21] L V Branets S S Ghai S L Lyons and X-H Wu ldquoChallengesand technologies in reservoir modelingrdquo Communications inComputational Physics vol 6 no 1 pp 1ndash23 2009
[22] G Caumon G Laurent N Cherpeau et al ldquoStructural frame-work and reservoir gridding current bottlenecks and wayforwardrdquo in Proceedings of the GUSSOWGeoscience Conferencep 8 Banff Canada 2011
reservoirs Baltim fields (South East and North) comprisetwo separate gas pools named ldquolevel III lowerrdquo and ldquolevelIII mainrdquo within the upper Messinian Abu Madi FormationThe trap is a structural-stratigraphic type with pinch-outagainst incised AbuMadi Paleovalley boundaries and is fault-bounded in the northern and southern part Identificationof stratigraphic architecture not only helps understand thegeological history but also has implications for hydrocarbonexploration as the confinement of flow in an incised valley hasgreat implications for channel amalgamation and producesfavorable reservoirs with potential two-way closure The AbuMadi reservoirs shape influences the seismic response ofthe incised Abu Madi Paleovalley making it necessary toaccount for 3D effects in order to obtain accurate resultsThe accuracy of the estimated thickness of each Abu Madireservoir is a critical element in assessment of reservesvolumes of hydrocarbons in place and production profilesThe promising locations of the future development wellsbased on the integration of seismic and well data coincidewith the up-to-date locations of drilling wells in the Baltimarea and locate at the center of the Abu Madi Paleovalley 3Dgeometricmodel of AbuMadi reservoir in Baltim area shouldbe kept in mind during future field development decisions
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
The authors wish to express their gratitude to Egyptian Gen-eral Petroleum Corporation (EGPC) and Belayim PetroleumCompany (PETROBEL) for providing the seismic lines welllogs and other relevant data Ministry of Higher Educationamp Scientific Research andMinistry of Petroleum in Egypt arealso acknowledged for promoting advancement in researchand establishing a possible future linkage between the indus-try and university They thank Schlumberger for furnishingthe Petrel software for the seismic interpretation
References
[1] S Dalla H Harsy andM Serazzi ldquoHydrocarbon exploration ina complex incised valley fill an example from the lateMessinianAbu Madi formation (Nile Delta Basin Egypt)rdquo The LeadingEdge vol 16 no 12 pp 1819ndash1826 1997
[2] Egyptian General Petroleum Cooperation (EGPC) Nile DeltaandNorth Sinai A Field Discoveries andHydrocarbon Potentials(A Comprehensive Overview) Egyptian General PetroleumCairo Egypt 1994
[3] M Alfy F Polo and M Shash ldquoThe geology of Abu Madigas fieldrdquo in Proceedings of the 11th Petroleum Exploration andProduction Conference pp 485ndash513 Cairo Egypt 1992
[4] I El Heiny R Rizk and M Hassan ldquoSedimentological modelfor AbuMadi sand reservoir AbuMadi field Nile Delta Egyptrdquoin Proceedings of the EGPC 10th Exploration and ProductionConference pp 1ndash38 Cairo Egypt 1990
[5] J D Pigott and M I Abdel-Fattah ldquoSeismic stratigraphy of theMessinian Nile Delta coastal plain recognition of the fluvial
Regressive Systems Tract and its potential for hydrocarbonexplorationrdquo Journal of African Earth Sciences vol 95 pp 9ndash212014
[6] R A Abu El-Ella ldquoTheNeogene-Quaternary section in theNileDelta Egypt geology and hydrocarbon potentialrdquo Journal ofPetroleum Geology vol 13 no 3 pp 329ndash340 1990
[7] J C Dolson M V Shann S Matbouly C Harwood R Rashedand H Hammouda ldquoThe petroleum potential of Egyptrdquo AAPGMemoir vol 74 pp 453ndash482 2001
[8] M I Abdel-Fattah and R M Slatt ldquoSequence stratigraphiccontrols on reservoir characterization and architecture casestudy of the Messinian Abu Madi incised-valley fill EgyptrdquoCentral European Journal of Geosciences vol 5 no 4 pp 497ndash507 2013
[9] J Harms and J Wray ldquoNile Deltardquo in Geology of Egypt R SaidEd pp 329ndash343 A A Balkema Rotterdam The Netherlands1990
[10] M H Mohamed Evaluation of hydrocarbon potentiality ofMiocene rocks in the Northern portion of Abu Madi Paleovalleyoffshore Mediterranean Sea Egypt [MS thesis] Faculty ofScience Suez Canal University 2012
[11] M I Abdel-Fattah ldquoPetrophysical characteristics of the mes-sinian abu madi formation in the baltim east and north fieldsoffshore Nile delta Egyptrdquo Journal of PetroleumGeology vol 37no 2 pp 183ndash195 2014
[12] A Rizzini F Vezzani V Cococcetta and G Milad ldquoStratigra-phy and sedimentation of a Neogene-Quaternary section in theNile Delta area (ARE)rdquo Marine Geology vol 27 no 3-4 pp327ndash348 1978
[13] M Bacon R Simm and T Redshaw 3-D Seismic InterpretationCambridge University Press New York NY USA 2003
[14] M E Badley Practical Seismic Interpretation InternationalHuman Resources Development Corporation Boston MassUSA 1985
[15] M B Dobrin and C H Savit Introduction to GeophysicalProspecting McGraw-Hill New York NY USA 4th edition1988
[16] O L Anderson and J D Pigott ldquoSeismic technology and lawpartners or adversariesrdquo Energy and Mineral Law Institute vol24 2004
[17] A R Brown Interpretation of Three-Dimensional Seismic DataAmerican Association of Petroleum Geologists and the Societyof Exploration Geophysicists 6th edition 2004
[18] O Catuneanu ldquoSequence stratigraphy of clastic systems con-cepts merits and pitfallsrdquo Journal of African Earth Sciences vol35 no 1 pp 1ndash43 2002
[19] O Catuneanu V Abreu J P Bhattacharya et al ldquoTowardsthe standardization of sequence stratigraphyrdquo Earth-ScienceReviews vol 92 pp 1ndash33 2009
[20] A M Salem J M Ketzer S Morad R R Rizk and I S Al-Aasm ldquoDiagenesis and reservoir-quality evolution of incised-valley sandstone evidence from the Abu Madi gas reservoirs(upper Miocene) the Nile Delta Basin Egyptrdquo Journal ofSedimentary Research vol 75 no 4 pp 572ndash584 2005
[21] L V Branets S S Ghai S L Lyons and X-H Wu ldquoChallengesand technologies in reservoir modelingrdquo Communications inComputational Physics vol 6 no 1 pp 1ndash23 2009
[22] G Caumon G Laurent N Cherpeau et al ldquoStructural frame-work and reservoir gridding current bottlenecks and wayforwardrdquo in Proceedings of the GUSSOWGeoscience Conferencep 8 Banff Canada 2011
![ExperimentalValidationoftheElectrokineticTheory ...downloads.hindawi.com/journals/ijge/2012/514242.pdf · Mikhailov et al. [36] and Haines et al. [39] compare seismoelectric synthetic](https://static.documents.pub/doc/80x56/6041bbc13a96f6316f3c2af0/experimentalvalidationoftheelectrokinetictheory-mikhailov-et-al-36-and-haines.jpg)
