Marine shale reservoir evaluation in the Sichuan Basin-A case study of the Lower Silurian Longmaxi marine shale of the B201 well in the Baoluan area, southeast Sichuan Basin, China

Based on the total organic matter (TOC) content, brittle minerals (quartz + feldspar) content, total gas content, porosity and production data of eight vertical and twenty-three horizontal shale gas wells in the Sichuan Basin, a new reservoir evaluation method for the marine shale reservoirs of the Sichuan Basin is developed. In this study, based on the analytic hierarchy process (AHP) and deviation method, a comprehensive evaluation index (CEI) was proposed to evaluate the marine shale reservoir. According to the CEI and the production data, three type marine shale reservoirs were proposed. The CEI was applied to evaluate the Wufeng-Longmaxi marine shale of the B201 well. The results show that the Wufeng-Longmaxi marine shale is the low quality shale reservoir. The comprehensive evaluation criteria proposed in this study can also be applied to evaluate the marine shale reservoirs in other areas in the Sichuan Basin through the verification of several other shale gas wells in the Sichuan Basin.