The Application of in-situ Stress Prediction in Shale Gas Reservoir Through Pre-stack Seismic Anisotropy Inversion – A Case Study from Sichuan Basin, SW China.

Summary Shale gas reservoir in deep burial has the features of developed fracture and complex in-situ stress property. To improve the accuracy of stress prediction for shale gas reservoir, we proposed that Differential Horizontal Stress Ratio (DHSR) evaluate the in-situ stress property for shale gas reservoir in function of Poisson’s ratio and fracture density. First of all, new rock physics model for shale gas reservoir is established considering the influence of Total Organic Content (TOC), fracture and anisotropy. Then, pre-stack angle gathers of different azimuthal angles is obtained by Offset Vector Tile (OVT) processing. Finally, pre-stack seismic anisotropy inversion was executed to obtain the Poisson’s ratio and fracture density. DHSR can be estimated by above two parameters. The real data test demonstrated that the predicted DHSR is consisting with prior geology information. The stress evaluation can offer useful geophysical evidence for hydraulic fracturing and well track design.