In-situ stress prediction method and research of shale reservoir based on VTI medium
In-situ stress plays an important guiding role in shale gas collection and reservoir transformation,and accurate in-situ stress prediction can provide the basis for optimizing fracturing transformation.Longitudinal anisotropy exists in shale reservoirs.In order to improve the accuracy of shale reservoir in-situ stress prediction,shale reservoir is equivalent to trans-versely isotropic media(VTI)model.Combining with equivalent model stiffness matrix parameters,elastic coefficient and structural strain coefficient,a three-dimensional simulation of shale reservoir in-situ stress field and stress difference ratio is carried out to predict the value,stress direction,and stress difference ratio of horizontal principal stress.The relationship be-tween in-situ stress and related parameters of reservoir fractures and gas content is analyzed.The method is applied to the pre-diction of ground stress of the Longmaxi Formation shale reservoir in the test work area.The results show that the prediction results of ground stress based on VTI medium model are more accurate than those based on the isotropic model,and the stress difference in the work area is more significant than that of the whole area.Fracturing modification is more complicated,and forming a better fracture network is difficult.With the increase of horizontal maximum principal stress,the curvature value de-creases,and the gas content decreases.
国家科技期刊平台
NSTL
万方数据
