Study On Pore Pressure Prediction In Shale Gas Reservoirs From Wufeng To Longmaxi Formation In The Southern Jiaoshiba Area

As the development of the shale gas resources exploration is increasing,especially the shale gas field block of Fuling in China, the experience of exploration for the construction of phase I and phase II has shown that pore pressure prediction in shale gas reservoir is the key factors influencing high yield of the shale. Pore pressure prediction in shale gas reservoir from Wufeng member to Longmaxi member in the southern Jiaoshiba block of Fulin shale gasfield directly determines the shale gas production finally. In addition,pore pressure prediction in shale gas reservoirs ensures the high quality, efficient, safe drilling and also is key to protect hydrocarbon reservoirs. Only master the layer pore pressure parameters, can adopt the reasonable density of drilling fluid, improve the quality of drilling and completion, reduce drilling costs. This thesis carried out the prediction research about pore pressure prediction in shale gas reservoir from Wufeng member to Longmaxi member in the southern Jiaoshiba block of Fulin shale gasfield. The result has an important significance to improve the study area of shale gas exploration and production of precision.Shale gas reservoir from Wufeng member to Longmaxi member in the southern Jiaoshiba block, which experienced intense tectonic movement, resulted in the tectonic characteristics of the area with alternating uplifts and depressions. Early fracture was destroyed by late fracture leads to the areas with complex surface conditions and structures. Existing drilling and pressure test data are very scarce. The low S/N of acquired seismic data is a big problem. Based on available data and production requirements, in this paper, the model selection of the pressure balance method and the prediction of the three-dimensional pore pressure in the area of the south of the Jiaoshiba are carried out. Bowers, Eaton and Fillppone model are used to calculate the pressure value of the well point. The Fillppone model is used to predict the three-dimensional pore pressure by using the actual drilling fluid density. Based on the relationship between the pressure of the drilling fluid density test point and various elastic parameters, the prediction method of the elastic parameter fitting is carried out, and the three parameter pressure prediction model of the southern of Jiaoshiba is established. Through the AVO inversion, the seismic velocity of the shale in the Fillppone model and the compressional wave impedance, Poisson's ratio and Young's modulus of the three parameters are obtained, which makes the formation pressure prediction results more precise and accurate.The fine 3D formation pressure prediction based on the principle of pressure balance method is realized by Fillppone model. Based on the relationship between the pressure of the drilling fluid density test point and various elastic parameters, the prediction method of the elastic parameter fitting is carried out, and the three parameter pressure prediction model of the southern of Jiaoshiba is established. By comparative analysis between the three parameter pressure prediction model and the Fillppone model, we can summarize that pressure precision is improved. The results of this thesis will provide guidance for the "sweet spots" prediction and production practice of the shale gas research in shale gas reservoir from Wufeng member to Longmaxi member in the southern Jiaoshiba block of Fulin shale ga in the late period.