Postt and Pre--Sttack Seiismiic Inversiion Techniiques ffor Reservoiir Charactteriizattiion,, Siimiian Fiielld,, Offffshore Niille Delltta --Egyptt

Abstract

The Simian Field is a Pliocene dry gas field located in the eastern part of the West Delta Deep Marine (WDDM) concession, offshore Nile Delta, Egypt. The field is comprised of sandstone reservoirs within channel complexes that are more confined with stacked sands within sinuous channels in the South and more bifurcated sinuous channels in the North with a sheet-like deposit in the North West. With estimated Gas-Initially-In- Place (GIIP) at ca.3.6 TCF and field cumulative gas production as of YE 2010 of about 1.3 TCF. Some of wells have suffered from an unexpected productivity. Therefore, it was very important to understand the geological evolution and sedimentary environments of this kind of facies, to understand the seismic signature in such complex system. So, the aim of this study was to undertake a post and pre-stack seismic inversion to investigate the extent to which lithological, facies and fluid effects could be determined in the Simian field. Four wells and 3D seismic volumes (full-, near-, mid-, and far-angle stacks) were available for this study. The volumes between 2200 and 3000 ms were inverted for P-impedance, S-impedance and Density. The product of the post stack inversion was insufficient to differentiate geologic features while the pre-stack inversion products were used successfully in differentiating Lithology and fluid contents. In addition, the rock physics analysis was successfully used in finding the relationships that used to differentiate the facies identified in the wells.