Delineating oil-sand reservoirs with high-resolution PP/PS processing and joint inversion in the Junggar Basin, Northwest China

Abstract

Dramatic lateral lithological variations in the fluvial sediments in Chepaizi, in the Junggar Basin of Northwest China, have posed challenges in distinguishing true and false “bright spots” in oil-bearing sand reservoirs. A high-resolution multicomponent seismic survey and joint prestack PP and PS inversion conducted recently provided an effective technique for solving the problem and successfully delineating the characteristics of the reservoir. This is due to the different reflection response of shear waves to the lithology and fluid content, and their ability to resolve thin layers. Surface-consistent amplitude- and resolution-preserving pro-cessing produced high-quality prestack PP and PS migrated gathers and stacks for extracting seismic attributes. Application of joint prestack PP and PS inversion resulted in higher fluid factors and lower [Formula: see text] in oil-bearing sands compared with dry sands. The correlation between the inversion and the existing well data suggests that high-resolution multicomponent AVO can reduce drilling risks and provide more accurate reservoir characterization.