Application of multicomponent seismic data to tight gas reservoir characterization: A case study in the Sichuan Basin, China

Abstract

Combining PP and PS-waves from multicomponent data is an effective hydrocarbon characterization strategy because these two wave types are sensitive to different subsurface properties. We present a case study using multicomponent data to characterize tight sandstone gas reservoirs in the Jurassic Shaximiao Formation, the western Sichuan Basin, China. In the study area, PP data have difficulties to distinguish sandstones, mudstones and gas sand, while recently acquired multicomponent data show potential for the joint characterization of lithology, porosity, and gas saturation from the combination of PP and PS reflections. Sandstones and mudstones show small P-velocity contrasts and large S-velocity contrasts. Thus, PS data provide a more accurate description of sandstones as a substantial proportion of sandstones are undetectable from PP sections. P-impedance is sensitive to sandstone porosity variation, and seismic-predicted porosities based on impedance inversion are in good agreement with log-interpreted porosities. The ratio of P-velocity to S-velocity is sensitive to gas accumulation, and the ratios derived from joint PP-PS prestack inversion are determined to be better than from PP prestack inversion in terms of their agreements with logs and distinct gas-sand boundaries.