Study On Geostress Prediction And Crack Identification Method Of Conventional Logging In Qigu Area

Taking the actual exploration of Qigu anticline area in the southern margin of Junggar basin as an example,the geostress analysis and crack identification are carried out.First,the logging data are corrected and normalized;and then the formation parameters are processed to obtain the curves of porosity,mud content and water saturation of the five wells in the area.In view of the characteristics of complex lithology and strong heterogeneity in this area,the construction method of physical volume model of strata rock is studied,and the rock mineral content of the target layer is obtained by the optimization method.The shear wave velocity in this area is predicted by the improved Biot-Gassmann theory.By comparison,it is found that the predicted shear wave velocity is basically the same as the measured shear wave velocity.On this basis,the study of geostress prediction is carried out in this study.The dynamic elastic modulus and overlying strata pressure are calculated by the P-wave and S-wave velocity logging curves and the density logging curves respectively.The pore pressure is predicted based on the effective stress principle.Then according to the relationship between pore elasticity theory,we calculate vertical geostress,maximum and minimum horizontal stress and other parameters.Finally,the method of support vector machine analysis is used to identify the fractures in tight reservoirs.This study provides theoretical support for reservoir prediction.