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Dr Cathy Hollis
Carbonate Depositional Systems – Malampaya, Philippines
EART 20020 Integrated Subsurface Description 2013-2014
Jahanzeb Ahsan 8529193
5-9-2014
TABLE OF CONTENTS
ASSIGNMENTS ........................................................................................................................................ 1-7
ASSIGNMENT 1 ............................................................................................................................................. 1
ASSIGNMENT 2 ............................................................................................................................................ 3
ASSIGNMENT 3 ............................................................................................................................................ 6
REPORT ON MALAMPAYA GAS FIELD .............................................................................................. 8
REFRENCES ...............................................................................................................................................10
Assignment 1
Land and Sea configuration for Miocene
Most of Asia, parts of American continents e.g. Florida and Europe were covered in sea water. This age was the initial step for cooling trend before the Earth’s
temperature dropped sharply (Middle Miocene Climate Transition). Antarctica was smaller than it is today. Most of the continents and land masses were covered in
water – Figure 1.
Black Sea, Mediterranean Sea and Persian Gulf were interconnected in Miocene age. The Red Sea was smaller than it is today and was blocked from Arabian Sea. The
sea level fluctuation is shown below.
Climate information for Miocene
Climate during this time was generally like today but relative to today it was warm. Western Asia was mostly
wet, and warm i.e. tropical climate. North and South poles were cold but not as it is today, as glacification
occurred from in Middle Miocene about 14.8 to 14.5 Ma. Region near equator were tropical. Further from
equator it became arid and warm before getting cool to cold towards North and South Pole as shown in
Figure 2.
Conclusion
The warm Tropical climate, relative low sea level (fluctuating), abundant sun light – closeness to equator,
and moderate to low clast input at the region of Malampaya field at that time were perfect for the carbonates
to form. The tectonic plate movement as can be seen by the attached pictures in this assignment suggest
optimum conditions for Malampaya/Nido carbonate reservoir to develop.
Relative sea level history of Malampaya field. From Grotsch
and Mecandier (1999)
1
Philippines
2
Assignment 2
Attach the work done scanned.
3
Pagasa clastic
Pre-Nido clastic
4
Low porosity – Black High porosity – red
5
Assignment 3
Ma-1 and Ma-5 share same lithofacies, but the time and space varies due to depositional processes and factors varied on both sides of the formation due to one being
on land-ward side and the other at sea-ward sides. Ma-2 do not have early Miocene deposit.
The Malampaya field consist of high porosity and low porosity zones subsiding each other, mainly carbonates.
All of the
samples
were
collected
from side
wall
No cores
recorded
Mixture of cores and side wall samples to identify the facies, for Ma-5 and Ma-2
Nido carbonates are divided into 11 units by Fournier, et al. 2005.
Intra-Nido
6
Pagasa clastics
Increase in water saturation: Sw
increasing downwards.
7
Name: Jahanzeb Ahsan Integrated Subsurface techniques ID: 8529193
1. Cenozoic Carbonate Systems of Australasia edited by Andrew Morgan.
Carbonate Depositional Systems – Malampaya,
Philippines
Malampaya is carbonate based offshore gas field located north west of
Palawan Island, Philippines. The usual sea depth ranges from 850 to 900
meters, discovered in 1989 contains generous volume of gas of up to 650
meters. Under this is an oil border of about 56 meters1 which is primarily
Oligocene – Miocene. In past years many authors have discussed Malampaya
in detail e.g. Fournier et al. (2004, 2005). The architecture of the reservoir
is complex relative to other carbonate reservoirs. Gas from Malampaya is
used to generate electricity – pipelines covering a distance of 534 km from
wells to land. There are 23 contract areas covering an area of about
112,000 km2 of which 85 % is in deep water.
8
Name: Jahanzeb Ahsan Integrated Subsurface techniques ID: 8529193
1. Cenozoic Carbonate Systems of Australasia edited by Andrew Morgan.
Malampaya gas field is based on Nido limestone. The source
rock having deep-water lithofacies (marl and deep water
carbonates) is in South west Palawan are Cretaceous pre-rift
unit Paleocene to early Oligocene Synrift section. The average
total organic carbon is about 1.8 % TOC. The sync-rift unit (i.e.
Paleogene) is deep marine Shale and marl with average of 1.3
% TOC. Followed by source is reservoir which is Oligo-Miocene
carbonate at approx. 3000 m TVDSS (deep-water) as well
(average porosity of 25 %). The seal is provided by Bathyal shale
(Pagasa) and trap is stratiographic anticline.
Stochastic stratiographic well correlation method is used for
Malampaya build-up. Out of 10 wells seven are cored and a high
resolution 3D seismic survey (by shell in 2002 – increased the
vertical resolution from 80m to 50m and reduction in noise
within the reservoir). Correlation of well data is used to study
diagenetic units as previous studies emphasized rock properties
are controlled by diagenesis. Correlation rules – Stratigraphic
(Fourier & Borgomano, 2007):
1. Two units are correlated if they are of same diagenetic
type.
2. If they display a similar well log pattern.
In case of lithostratigraphic correlation there should be no
distortion in the signal and sedimentary record is presumed to
be complete that is, there no erosion on the considered
stratigraphic unit. Another method by Flang et al. (1992) is used
in which well logs are converted into simple patterns. Figure 2
shows section of diagenetic units made from stratigraphic
correlations computed by recommended algorithm.
Depostion of Nido limestone happened at the edge of sloped
block as a result of rifting phase of the China sea (Fournier et
al. (2005). The reservior is made from reef related Nido
carbonate and reefal Miocene reefal limestone.The Nido
carbonate was deposited during the drifting stage during
Oligocene-Early Miocene (Clyde H. Moore, William J.Wade, et
al. 2013). The north-west was oceanic margin and south-west
land margin – eastern basin. There is ample evidence of reef
debris where oceanic margin reside – reef environment
dominat. North-East to South-West reefal (Nido Limestone)
was controlled by the rift fault system under the Nido
Limestone.
Figure 1. (A) Trap (B) Seal (C) Reservoir (D) Basement – clastic. (Source: Department of Energy, Philippines). NOT TO SCALE.
C
A
B
Figure 2. Stratigraphic correlation. Reference well MA-1, 2 and 5. (Source: F. LALLIER et al.).
Mantinloc
Pagasa
Nido
Pre-Nido
D
Oceanward margin Drowning Succession Landward margin
Aggradation
Backstepping
Figure 3. Malampaya depositional model. (Source: Grötsch and Mercadier, et al.2009).
D
9
Name: Jahanzeb Ahsan Integrated Subsurface techniques ID: 8529193
1. Cenozoic Carbonate Systems of Australasia edited by Andrew Morgan.
According to Fournier & Borgomano (2007), the reservoir in
Malampaya was mainly controlled by diagenetic processes which
he classified into five types namely Ia, Ib, II, IIIa and IIIb – shown in
figure 4. Figure 4 shows well to seismic correlation, along with
diagenetic units, offering geobodies described by reservoir
properties and particular pore type. Porosity of each diagenetic
unit is shown below in figure 5.
The permeability of Malampaya gas field is reasonably well which
can be seen clearly in figure 6 below.
Carbonate reservoir are the most abundant and significant
hydrocarbon reservoirs in the world and many exist in South-
East Asia. Sometime many features are similar between the
reservoirs of same kind, but differences such as bio-marker and
content of individual gas/oil may vary. The summary of
comparison Malampaya with two other gas field by Fournier &
Borgomano, 2007) is shown in figure 8 on the next page. The
table suggest that the three fields share many common features
such as lithofacies, dominant biological components porosity
and etc. The petrophysical properties are controlled by
secondary porosity (Fournier & Borgomano, 2006). Difference
between the compared cases is acoustic contrast between the
lithological and diagenetic units.
It is difficult to categorize carbonate reservoir, mainly due to
heterogeneity. The recovery factor of all oil fields is about 35 %
but it’s a fact that recovery factor of carbonate gas reservoir is
lower than that of sandstone. Sand can travel a great distance
and deposit in another place far from its origin whereas
carbonate are locally formed close to their origin. Sand is less
reactive to chemical reactions whereas carbonates are bound
to react hence their initial porosity and permeability is high
(35% to 75%), but decrease sharply as sediments are altered
and depth of burial increase plus diagenesis. Heterogeneity in
Malampaya reservoir exist at all levels.
In most carbonate reservoir like Malampaya the rock matrix
holds the hydrocarbon, whilst fractures often provide main flow
paths. In fact the E11 offshore Malaysia share almost similar
shape, nearly shape porosity, age, constituents and
aggradational zones that leads to final drowning [William
Andrew Morgan, 2010]. More details for E11 and its comparison
is shown by Andrew Morgan et. al 2010.
Malampaya is one of the most studied and well documented
carbonate reservoir. Core analysis, seismic imaging, well
correlations, laboratory tests and use of analogues have been
performed on Malampaya to understand it better. Though
there is little that can be further done on Malampaya analysis
uncertainty at micro and macro level can still exist. Few other
types of tests that can be done may include: Soil sampling, in-
situ tests such as cone penetrometering and Electromagnetic.
Figure 4. Stratigraphic Model (Source: Fournier & Borgomano, 2007).
MA-3 MA-9 MA-4 MA-6 MA-7 MA-5 MA-8
Rudstone/reef debris or uppermost karst Rudstone-grainstone intermediate reef debris Grainstone-wackestone Cemented/dense layers “intra Nido” unit Cemented reef/slope Cemented slope
Figure 6. Source Shell
Figure 5. Histogram of acoustic impedance and porosity (Source: Fournier & Borgomano, 2007).
Quartz rich packestone Grainstone
Packestone to floatstone Wackestone to packstone
Packstone to floatstone
% Porosity
Figure 7. Porosity in depth v/s lateral distance (Source: Seismic imaging of carbonate reservoirs and systems: AAPG Memoir 81,
page 181).
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Name: Jahanzeb Ahsan Integrated Subsurface techniques ID: 8529193
1. Cenozoic Carbonate Systems of Australasia edited by Andrew Morgan.
Figure 8. Comparison of Malampaya, Luihua and Luconia
References
Dancer, N. & B.V, S. P., n.d. Reservoir Characterisation of the Malampaya Field, a Carbonate ReefalBuild-up in the Philippines. s.l.:s.n.
Department of Energy, Philippines, n.d. Department of Energy. [Online]
Available at: http://www.doe.gov.ph/microsites/archives/win_opp/cd/SPEX/Malampaya%20Subsurface.pdf
[Accessed 11 April 2014].
Lallier, F. et al., 2012. Relevance of the stochastic stratigraphic well correlation approach for the study of complex carbonate settings:
Application to the Malampaya buildup (Offshore). In: Advances in Carbonate Exploration. s.l.:The Geological Society London.
Moore, C. H., 2001. In: CARBONATE RESERVOIRS: POROSITY, EVOLUTION & DIAGENESIS IN A SEQUENCE STRATIGRAPHIC FRAMEWORK:
Porosity Evolution and Diagenesis in a Sequence Stratigraphic Framework. s.l.:Elsevier, pp. 376-379.
Moore, C. H. & Wade, W. J., 20013. Carbonate Reservoirs: Porosity and diagenesis in a sequence stratigraphic framework. s.l.:Newnes.
Neuhaus, D. J. B., Jauffred, J.-C. & C. Mercadier, S. O. a. J. G., 2004. Quantitative seismic reservoir characterization of an Oligocene – Miocene.
Seismic imaging of carbonate reservoirs and systems: AAPG Memoir 81, pp. 169-183.
Otto Energy Limited, 2008. Offhore Philippines Farm-in Opportunities. [Online]
Available at: http://www.asx.com.au/asxpdf/20080407/pdf/318fp2f340flnx.pdf
[Accessed 11 April 2014].
PNOC Exploration Corporation, n.d. The South East Asia Petroleum Exploration Society. [Online]
Available at: http://www.seapex.org/farmout_files/9956_sc632011seapexfarm-out.pdf
[Accessed 10 April 2014].
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