Interpretation of P- and S-Wave Prestack Inversion for Characterizing Morrow A Sandstone

Abstract

The Upper Morrow sandstones in the western Anadarko Basin have been prolific oil producers for more than five decades. Exploration for Morrow reservoirs has a tradition of being high-risk but high-reward. Detection of Morrow sandstones is a major problem in the exploration for new fields and the characterization of existing fields because they are very thin and laterally discontinuous. The Postle field in Oklahoma is undergoing CO₂ flood and for successful flood management it is important to characterize the Morrow A sandstone, which is the main reservoir in the study area. The S-wave velocity contrast between Morrow shale and A sandstone is strong as compared to P-wave velocity contrast, and therefore, multicomponent seismic data can help in characterizing these reservoirs. I have used P-impedance from prestack inversion of P data and the S-impedance and density from prestack inversion of SV data for interpretation in this paper. Stratal slicing method is used to get the P- and S-impedance and density maps. We find that the S-impedance map gives a better match with the Morrow A sandstone distribution as compared to the P-impedance map. The density estimation from prestack inversion of SV data is able to distinguish between low- and high-quality reservoirs. The porosity volume is estimated from density obtained from prestack S-wave inversion. The density and porosity maps obtained from seismic shows satisfactory match with the well log density and porosity maps. Some possible well locations are suggested based on the interpretation of inversion results.

AAPG Datapages/Search and Discovery Article #90216 ©2015 AAPG Annual Convention and Exhibition, Denver, CO., May 31 - June 3, 2015