Post on 03-Apr-2018
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GEOLOGIC MAP INTERPRETATION
RELATIVE AGE:
Shale
Sandstone
Unconformity
DYKE And SILL
Igneous rock intrusion and accompanying regional metamorphism
Sandstone
This was achieved by applying classical stratigraphic principles. These are the principles of (1) OriginalHoriz(2) Superposition, (3) Lateralcontinuity, (4) Cross-cuttingrelationships.
Youngest
Oldest
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Features and Sequence of events
X is sandstone
B is an Igneous Rock intrusion
Z shows a relationship to the igneous body and can bebest described as a region of metamorphism (changes in
mineral assemblage and texture that result from subjecting
a rock to conditions such as pressures, temperatures, and
chemical environments)
C is a Dyke and D is a sill
T is Sandstone A is a non-conformity
Y is shale
Sandstone was deposited first- earth forces acted on this layer causing a deformation of the layer (tilting
and folding) Igneous rock intrusion accompanied by Z which can be best described as a zone of metamorphism
Applying the principle of cross-cutting relationship, after the intrusion the dyke C cut across the igneous
formation (country rock) followed by D which is a Sill
After this there was a break in deposition accompanied by weathering and erosion which gave rise to an
unconformity (non-conformity)and subsequent deposition and erosion of the sandstone which tapers to
the right.
Finally, shale was deposited on the sandstone making it the youngest layer (principle of superposition).
SEQUENCE OF EVENTS
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TITLE
THE ROCKS SEEN
Sandstone A, Conglomarate B,Limestone D, Shale C, Salt dome G
THE RELATIVE AGES OF THE ROCK
The geological feature salt-dome is the youngest rock form secondly
D,C,B,A and G which is the oldest to the youngest rock
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THE GEOLOGICAL FEATURES
Anticline fold is indicated in green and the syncline fold is in red, fault is F
There was a deposition of limestone originally D
then erosion of the limestone occurs and also deposition of shale and
conglomerate and sandstones occurred
The red and green fold were created as a result of compression acting onthe joint formation and this created the fault F
We have the dyke formed as a result of intrusion at the surface due to
surface erosion
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MAJOR SUBDIVISIONS AND BRIEF GEOLOGICAL HISTORYOF THE NIGERIAN NIGER DELTA BASIN
Major subdivisions of
the Nigerian Niger Delta
are;
Benin formation Agbada formation
Akata formation
GEOLOGICHISTORY
Separation of the continental crust of the South America and Africa plates in the late Jurassic
rift, the event followed by early cretaceous subsidence of the African continental margin. . The
most important linked events in the chain of geologic episodes that built the Niger delta wasthe initiation of the Benue trough and its sequential filling up of marine sediments following
the cretaceous transgression (Reyment, 1955; Reyment and Tait, 1972)
The coastal sedimentary basin of Nigeria has been the scene of three depositional cycles.
The first began with a marine incursion in the middle Cretaceous and was terminated by a mild
folding phase in Santonian time.
The second included the growth of a proto-Niger delta during the late Cretaceous and ended in a
major Paleocene marine transgression.
The third cycle, from Eocene to Recent, marked the continuous growth of the main Niger delta.
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BENIN AGBADA AKATA
Environment of
Deposition
Continental
environmentTransitional
environmentMarine
environmentThickness >6000feet >10,000feet >4,000feetShale content 20% 40% 80%
Sand content 80% 60% 20%Age Miocene-recent Eocene-
OligoceneEocene-recent
Hydrocarbon
content
Very little
hydrocarbon
accumulation has been
associated with this
formation
Major
hydrocarbon
accumulations are found
in this formation
Source rock
Composition/Na
ture of deposits
Coarse grained,
poorly sorted, sub angular
to well-rounded and bears
wood fragments
Rich in micro-
fauna at the base
decreasing upward, poor
sorting and coarse grains
Presence of
Benthonic assemblages,
thin sandstone lenses
occur near the contact
with the overlying Agbada
formation
BENIN AGBADA AKATA
Environment
of Deposition
Continental
environment Transitionalenvironment MarineenvironmentThickness >6000feet >10,000feet >4,000feetShale content 20% 40% 80%Sand content 80% 60% 20%Age Miocene-
recent Eocene-Oligocene Eocene-recentHydrocarbon
content
Very little
hydrocarbon
accumulation has
been associated
with this formation
Major
hydrocarbon
accumulations are
found in this
formation
Source rock
Composition/
Nature
Coarse
grained, poorly
sorted, sub angular
to well-rounded and
bears wood
fragments
Rich in micro-
fauna at the base
decreasing upward,
poor sorting and
coarse grains
Presence of
Benthonic
assemblages, thin
sandstone lenses
occur near the
contact with theoverlying Agbada
formation
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A sedimentary rock is the second great rock class. Whereas
igneous rocks are born hot, sedimentary rocks are born cool
at the Earth's surface, mostly under water. They usually
consist of layers or strata; hence they are also called
stratified rocks. Depending on what they're made of,
sedimentary rocks fall into one of three types.
There are three type of sedimentary rock:
Clastic sedimentary rocks which are formed as a result of
eroded sediment.
Biogenic sedimentary rock which are formed from the
remains of living things.Evaporates which are formed by minerals precipitating out
of a solution.
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ARABIAN PENINSULASIMPLIFIED MAP OF THE ARABIAN PENINSULA
Geologically it lies on a tectonic plate of its own.
it consist of two distinctively different geological regions; (Western and Eastern region).
The Eastern Region is made up of mostly sedimentary limestone rock which deposited
in layers by expanding and receding ancient seas. These sedimentary layers where then
folded by tectonic pressure from east that resulted in the formation of mountains.
The large deposition of oil is found in the sedimentary folds anticline of the peninsula.
The original sediments of the peninsula are clarbonates, clastics and everporites
followed by marine sandstones and variegated shales.
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A MAP SHOWING OIL AND GAS FIELD OF THE PENISULA
PRODUCTION PROFILE OF OIL AND GAS IN THE PENINSULA
it has the largest oil field reserves in the world, especially the GHAWAR field, with
estimated remaining reserve of 70million bbls.
The arabian peninsula contains alone two third of the entire world estimated reserves.
As at 2010 saudi arabia has an estimated 260bbbl of crude reserves and 1.8mbbl ofNGL, of which 12mbbl/d is produced daily.
Also as at 2007, saudi arabia has 275trillion cubic feet of gas reserver of which 2.7 TCf
is produced daily.
Finally there ongoing and completed projects to improve the production capacity of
arabian peninsula, it is analyzed that production figures will more than double present
figures once these projects come on stream.
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North Sea Basin
North Sea
Netherlands, UK, Germany, Denmark, Norway
Major Subdivisions:
Northern / Central (80% of UK fields are under
development or on production).
Southern North Sea SNS (50% of UK fields are
under development or on production).Worldoil.com
E&P Companoes:
BG Group, BP, Chevron, Eni, ExxonMobil, Gaz de
France, Shell, Statoil
Geological History.
Pre-Devonian
Later Paleozoic Mesozoic.
Cenozoic
Tectonic Process:
Plate-margin effects (subduction).
Deformation
Almost all of the hydrocarbon fields in the southern partof the North Sea are gasfields
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NORTH SEA (FD & PROD)
FIELD DEVELOPMENT
PRODUCTION
Exploratorary of DutchGas field took
exploration offshore
leading to investigation
into the North Sea.
Formed through a period
of sequential
sedimentation , TheNorth Sea basin is
characterised by a rift
drift sequence.
Production has peaked twice but steadily declines
now. The earlier peak was during the mid 80s whentechnology and demand grew and production was
from 32 fields.
The second peak was 1999 when production was
from 136 fields.
The dip in between is due to fall in oil price and the
fitting of safety equipment post Piper Alpha.