Regional Diagenetic Law and Control of Diagenesis over Gas-Bearing Capacity of Tight Reservoirs in Deep Xujiaweizi Fault Depression, Songliao Baion

In order to understand diagenetic regularity and impact factors of the deep Xujiaweizi fault depression in Songliao basin, and their controlling over gas-bearing capacity of compact reservoir, this study focused on classification of diagenesis and discussed diagenetic features of each structural unit using fluid inclusion homogenization temperatures, Ro, TAI, Rock-Eval, organic acids, XRD, thin section, SEM, blue epoxy resin-impregnated thin sections. Results show that the Xujiaweizi fault depression is characterized by diagenesis intense in uplift and weak in depression. Compared with both areas on both sides of the depression, the central depression has high magnitude of uplift exhumation, high geothermal gradient, older formation and weak diagenesis. Oil- and gas-bearing capacity of the tight sandstone is obviously controlled by reservoir diagenesis, and bottom limits of gas exploration in sandstone and conglomerate beds responds respectively to depths of the middle stage (B1) of and late stage (A) of diagenesis.