Analysis on factors inducing abnormal high fracture pressure of deep tight sandstone gas reservoir

The deep gas reservoir of Western Sichuan Depression features in super depth, ultrahigh pressure, and complicated trap formation, so fracturing gets difficult. The reservoir may have abnormal high fracture pressure. The factors that may lead to the abnormal high fracture pressure of tight sandstone reservoir are studied in this paper. The tensile strength of rock increases due to the super tight reservoir. The high level of clay minerals of the rock and the presence of a large number of laminated, reticulation, porphyritic rocks result in the the increase in the carbon layer of plastic and the additional pressure caused by overpressure formation. All these above are the geological factors leading to the increase in formation fracture pressure. Engineering factors are mainly the following: the aberration of stress field near a hole induced by drilling may result in the increase in rupture pressure of no-crack formation. The formation fracture pressure may be caused by the fluid energy loss during the extension of cracks, the fluid flow friction, and the bending friction caused by bending cracks. The analysis of the main factors that may induce the abnormal high fracture pressure of the studied area is favorable for carrying out reservoir fracturing in the area in near future.