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Abstract: Stratigraphic Response to Growth Faulting in the Niger Delta

BOUROULLEC, R., H. D. JOHNSON, J. A. CARTWRIGHT, Imperial College, London, United Kingdom.

Understanding the style of displacement (continuous or by step) and the rate of movement of a growth fault is important for the prediction of stratigraphic architecture of oil and gas accumulations. The nature of the ductile level, such as salt or shale, has a dominant control in gravitational gliding but the influence of sedimentary load is frequently underestimate. This study attempt to quantify the interaction between sediments loading and fault displacement. This is base on an analysis of Upper Oligocene-Middle Miocene sediments and of three growth faults situated in the central part of onshore Niger Delta.

The kinematics of the hanging walls is deduced from the vertical component of displacement (subsidence and uplift) which has been measured from 26 wells using high-resolution sequence stratigraphic principles. Estimates of palaeobathymetry have been made through a detailed reconstruction of vertical sedimentary facies profiles. Variations in relative sea-level (accommodation space) has been obtained with a resolution of 0.5 to 1 Ma and is extrapolated between wells using 3D seismic data. Sedimentary architecture including channel orientation, facies distribution around faults plans and sand body stacking patterns has been determined from 3D seismic attributes, cores and well logs. These architectures and the restored paleogeographical maps are compared with the tectonic events to estimate the relative influence of fault displacements during deltaic progradation. Quantification of tectonic and stratigraphic processes is used to build a basin model taking into account sequence stratigraphy concepts and local tectonic displacement.

AAPG Search and Discovery Article #90937©1998 AAPG Annual Convention and Exhibition, Salt Lake City, Utah