Integrated seismic attributes and stochastic inversion for reservoir characterization: Insights from Wadi field (NE Abu-Gharadig Basin, Egypt)

Abstract

Sand-lithofacies distributions are a vital component of reservoir characterization and the generation of successful reservoir models. Through the integration of selected seismic attributes with post-stack stochastic seismic inversion reservoir distributions and architectures are accurately delineated for the Upper Cretaceous reservoir (Abu Roash “C”) in the Wadi field of NE Abu-Gharadig Basin, Egypt. Seismic interpretation and 3D structural modeling generate a regionally accurate image of the subsurface of Wadi field revealing a variety of structures: low-relief horsts and grabens, a faulted inversion-related anticline, normal and reverse faults (inverted basin phenomenon). Seismic attributes (second derivative and acoustic P-impedance) indicate that the Abu Roash “C” reservoir is characterized by the presence of two discrete sand-filled channels. The P-impedance attributes derived from post-stack seismic inversion utilized with the distributed petrophysical properties (density) predict the occurrence probability of the distinctive lithofacies in Abu Roash “C” reservoir. As stochastic seismic inversion provided an extensive vertical and lateral information set for the reservoir heterogeneity between wells, it was utilized as the definitive information requirement in generating the lithofacies models. The lithofacies obtained from integrating seismic attributes and inversion are calibrated with facies identified using well logs. The lithofacies model derived from this integrated approach provides an added geologic insight into the stratigraphic architecture and reservoir distribution and lessens exploration/development risk in the Wadi field. The resulting workflow is an effective tool for highlighting potential areas of better quality reservoir development, thereby demonstrating the value of this integrated approach.