As overpressure in continental shale formations in the Fuxing area of Sichuan Basin seriously affects well control safety, timely and accurate prediction of formation overpressure can effectively prevent the occurrence of accidents such as well kicks and blowouts, contributing to safe and efficient drilling operations. To this end, this paper adopts methods including combined logging curve analysis, loading–unloading curves, and acoustic velocity-density cross plots to analyze the overpressure genesis of continental shale in the study area. In view of the genesis mechanism characteristics of continental shale overpressure, this paper proposes a new pore pressure prediction method that comprehensively considers the composite pressurization mechanism of hydrocarbon generation expansion and undercompaction. The research results show that the gas logging of multiple wells in the study area shows abnormal values, and two wells have repeated abnormal gas logging values and well kick even after increasing the density of drilling fluid, which can effectively determine the abnormal increase of pore pressure in the formation. By integrating three kinds of overpressure genesis mechanism, the overpressure of the Lianggaoshan Formation in the study area is attributed to undercompaction, and the overpressure of the Dongyuemiao Formation is due to the composite effect of hydrocarbon generation expansion and undercompaction. The relative error of formation pressure predicted by the new method is only 4.6 %, with strong applicability and high prediction accuracy. The research results are of significance for the efficient exploration and development of continental shale oil and gas in the study area.
He et al. (Wed,) studied this question.