Applications of 3-D Structural Interpretation and Seismic attribute Analysis to Hydrocarbon Prospecting over X – Field, Niger – Delta
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Date
2010-02-25
Journal Title
Journal ISSN
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Publisher
IJENS
Abstract
Complexly faulted subsurface configuration is capable of causing erroneous deductions in the absence of a well
packaged interpretation approach and workflow for an oilfield exploration programme, thus a well prepared
analysis saddled on the use and integration of sufficient data is indispensable to the unravelling of complex field
subsurface structure as the search for oil and gas progresses into deeper waters. Suite of signatures from wireline
logs and seismic volume was employed to gain more insight into the complexities of the hydrocarbon hosting
units within and outside the vicinity of well control in the X-field Niger Delta. Horizons and fault interpretation
were carried out to produce subsurface structure maps. Amplitudes of the horizons mapped were extracted and
were used to study the distribution of the hydrocarbon sand.
Three hydrocarbon bearing reservoirs were delineated within the study interval, namely: ROJ A, ROJ C and
ROJ D. Well to seismic tie revealed that these reservoirs tied direct hydrocarbon indicators (bright spots) on the
vertical sections. The structure maps produced revealed a series of NW-SE and E-W trending growth faults and
fault echelons, most of which dip to the south. Fault assisted closures were revealed at the southern part of the
field, which correspond to the crest of roll over structures and possibly served as the trapping mechanism for the
reservoirs.
The reflection amplitude of the studied horizons shows a fine network of anomalies that can be correlated to the
prediction of the lateral distribution of the hydrocarbon sand. The conclusion of the study was that the western
part of horizon ROJ A is a highly prospective area as bright spots were observed in the region. Also in the
adjacent southern direction of this horizon, hydrocarbon accumulations have been confirmed from wells. These
gas sands are possibly trapped in anticlinal closures located in the same area. On the other hand, the results from
the study of horizon ROJ C suggest development opportunities in the southern area. High amplitude gas sands
are seen to spread to the south and stratigraphy was assumed to play a major role in hydrocarbon migration. The
study over horizon ROJ D reveal likely geologic features like regional sand pinch outs and channels in the
southern part of the field. Spectral decomposition interpretation was suggested to be used further in improving
the delineation of the thin reservoir sand bodies and for better outlining of their geometries but was not available
on the workstation used.
The study has shown the feasibility of integrating structural interpretation and instantaneous amplitude in
prospect identification and reservoir prediction.
Description
The research involved the delineation of hydrocarbon bearing reservoirs on well logs at a depth of between
8,000ft (2,134m) and 11,500ft (3,507m), 3-D structural interpretation and lateral mapping of the hydrocarbon
reservoirs. From well log analysis, three hydrocarbon-producing reservoirs were identified, namely: reservoirs
ROJ A, ROJ C, and ROJ D. Well-to-seismic tie revealed that hydrocarbon bearing reservoirs were associated
with bright spots on seismic sections. The bright spots were seen on attribute surface analysis carried out on the
horizon slice as high amplitude zones. They were used to map the lateral continuity of the gas sand observed in
the southern part of the field.
Keywords
reservoirs, fault, hydrocarbon, seismic, amplitudes, structures
Citation
Rotimi, O.J., Ameloko, A. A., & Adeoye, T. O. (2010). Applications of 3-D structural interpretation and seismic attribute analysis to hydrocarbon prospecting over X-field, Niger-Delta. Int J Basic Appl Sci, 10(4), 28-40.