Characteristics And Evolution Of Overpressures Within Mesozonic In Moxizhuang-yongjin Area

Based on the comprehensive analysis of geology,geochemistry and geophysics,this paper studies the present stress field depiction,the history of temperature pressure evolution,the mechanism of abnormal pressure and pressure system comprehensive division in the Moxizhuang-Yongjin area of Junggar Basin.First of all,the pressure prediction model is established by using the principle of effective stress equation and logging data to complete the longitudinal description of the drilling pressure system:MoXizhuang area showed two overpressure systems,the upper weak overpressure system maximum pressure coefficient of1.5,the lower overpressure system maximum pressure coefficient of 1.8;Zhengshacun area Showed an overpressure system,with a small increase rate of pressurization;two overpressure systems of the Xishanyao and Sangonghe formations are found in the Yongjin area.Using the seismic velocity data,lateral pressure prediction of the main strata is carried out.The overpressure of the Sangonghe Formation is mainly distributed in the area south of Zhengsha village.The overpressure centers are located in the Yongjin and the south of the depression area;the Xishanyao Formation is limited to Yongjin and south,the overpressure amplitude is slightly lower than that of the Sangonghe.In order to predict the pressure space constrained by the quantitative analysis of genetic mechanism,four relatively independent overpressure systems of Jurassic are divided.Based on the thermodynamic simulation of the minimum entrapment pressure of fluid inclusions,PetroMod simulates the geologic conditions of oil and gas and restores the pressure evolution of the main target strata.The overpressure evolution can be divided into J₁-J₃ and K-E,two complete pressure-relief cycles,N-Q YongJin only performance for the half pressurization cycle.