A novel evaluation on fracture pressure in depleted shale gas reservoir

Abstract

Fracture pressure is the key parameter both for horizontal drilling and hydraulic fracturing in the shale gas reservoir. Reservoir depletion will push for the change of the fracture pressure. Previous studies showed that fracture pressure will be decreased with reservoir depletion, which is not suitable for the anisotropic shale gas reservoir. Aiming at resolving this problem, a novel evaluation was established, which can be used to evaluate the influence on fracture pressure of the reservoir depletion, the anisotropy, and the well inclination. The results showed that the fracture pressure will be increased for the strongly anisotropic reservoir with reservoir depletion, and the fracture pressure has a tiny difference between the various anisotropic reservoirs before reservoir depleted, but a larger difference will appear after reservoir depleted, at the later depletion period, the fracture pressure is higher for the stronger anisotropic one. When the anisotropy and the depletion are both the same, the fracture pressure for the higher deviated well is lower. The method and the results can provide a theoretical basis both for the drilling and hydraulic fracturing in depleted shale gas reservoir.