Complementary Structural Analysis of Channelized Turbidites in the Offshore Niger Delta: Integration of 3-D Seismic Data, Inversion of Extra-Deep Azimuthal Resistivity Data, Gamma and Density Borehole Images

Abstract

Integration of subsurface geological and petrophysical data is necessary for a robust structural interpretation. Complementary structural analysis is a comparative procedure that involves pairing structural interpretations from two or more sources for improved understanding of subsurface structures. The pairing increases the robustness of any structural analysis by providing the geological (type of depositional environment, temporal and spatial considerations) or any other measurement (e.g. tool type, depth of investigation) explanation to support the outcome. In oil field management, structural analysis of the reservoir provides invaluable information on subsurface structural features (faults, fractures) and reservoir parameters that may impact oil drainage. In this study, a complementary structural analysis scheme was applied to a Mid- to Late Miocene channelized reservoir in the Niger Delta area. The reservoir consists of several individual turbidite complexes including stacked channels and extensive, lobate sheet sands. Multiple faults, multi-layered, heterogeneous and discontinuous sand bodies are some of the peculiarities of the reservoir and which required characterization for optimum drainage strategy and field management. This case study shows an integrated structural interpretation from dip measurements derived from inversion of extra-deep azimuthal resistivity data, gamma and density images, and 3D seismic. This has allowed for a better visualization of the near-wellbore structural geology of the wells drilled in the study area, detection of subsurface structural features, discontinuities, and the robust determination of key reservoir parameters (reservoir thickness, geometry) of the drilled channelized sand bodies. Our approach also underscored the importance of complementary structural analysis in the characterization of channelized turbidites during oil field management.

AAPG Datapages/Search and Discovery Article #90332 © 2018 AAPG International Conference and Exhibition, Cape Town, South Africa, November 4-11, 2018