ABSTRACT:

The understanding of in situ stresses is very important in the oil and gas exploitation. To provide an effective guidance for the field operations including drilling, fracturing and production, the finite element method was employed to model the in situ stresses as well as pore pressure in Sichuan shale gas reservoir embedded fault networks. The linear elastic model was used to depict the deformation of shale gas reservoir, and the friction behavior on the surfaces of faults was considered. Enough trial numerical experiments were used to obtain an optimized prediction that is expected to agree with actual test data. The information of in situ stresses in whole the geometric model as well as main shale gas reservoir layers, and on the fault surfaces can be acquired. Case studies on Changning and Weiyuan regions, Sichuan Basin, southwest China, were conducted, and the in situ stress information including stress gradients and horizontal stress differences in three typical areas was predicted. The orientation of horizontal maximum principal stress in the Changning and Weiyuan regions is almost east-west. The fault only affects the magnitude and orientation of situ stresses near itself, but have little effect on those in the farther strata.

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