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The Role of 
Fault
Kinematics and Capture in the Western Niger
Delta and the Control of Sediment and Reservoir Distribution*
By
Jacob Diedjomahor1; Charles Kluth2, Eric Frost3, and Robert Mellors3
Search and Discovery Article #40092 (2003)
*Adapted from “extended abstract” for presentation at the AAPG Annual Meeting, Houston, Texas, March 10-13, 2002.
1Chevron, San Ramon, CA
2Chevron, San Ramon, CA; present address: Littleton, CO ([email protected]; [email protected])
3San Diego State University, San Diego, CA ([email protected])
General Statement
Large,
south-dipping cuspate normal faults separate structural trends within the shelf
of the western Niger Delta (Figures 1 and
2). The growth and linkage of these faults exerts
control on the distribution, thickness and quality of reservoirs. We have
examined 3D seismic, well, and biostratigraphic data to examine the structural
control over reservoirs in detail in order to understand the relationship
between the structure and reservoirs so that we could explore and develop fields
more efficiently. The major faults link together to form trends through the
process of fault capture. These faults form a linked system whose temporal
pattern of movement is documented in the sedimentary record. Four-way structural
traps occur in the hanging walls of the major faults.
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Structural Control on Sediment and Reservoir Distribution
A chronostratigraphic framework was established by interpreting and
mapping time correlative sequences and their associated sediments. A
strong structural control is observed on sediment and reservoir
deposition and distribution (Figures 3 and
4). There is an overall thickening of each
sequence basinwards from one structural trend to the next (Figure
4). There is also a decrease in reservoir rock thickness and
net-to-gross ratio from one structure-building
Structural
control on sedimentation is also observed within each trend in an
along-strike direction, with decreasing net-to-gross ratio in reservoir
rock thickness towards |
Figure
1. Map of Africa showing Nigeria and the position of the Niger Delta and
the study area.
Figure
2. A 3-D view of the major structural trends in the study area.
Figure
3. Transverse profile A-A’ through the study area. (a) Interpreted time
seismic section. (b) Depth section showing faults, gamma-ray well logs
and sequence boundaries.
Figure
4. Longitudinal profile X-X’ through the study area. (a) Interpreted
time seismic section. (b) Depth section showing faults, gamma-ray well
logs and sequence boundaries.
Figure
5. Dip profile through the Meren Trend showing reservoir distribution
away from the major structure-building 