Effects of High Temperature and Overpressure on Deep Reservoir in Qiongdongnan Basin, Northwestern South China Sea

Abstract

Abnormal temperature and pressure with their effects on deep reservoir is the frontier in petroleum geology. Taking Qiongdongnan basin as a case study, the geological settings of this basin are primarily analyzed in this paper. Then, based on the full consideration of sedimentation and diagenesis, effects of abnormal temperature and pressure on deep reservoir are discussed. Main conclusions are drawn as following: (1) high geothermal or geothermal gradient accelerates the reduction of sandstone porosity, (2) high geothermal or geothermal gradient can improve the reservoir properties by promoting the dissolution of carbonate minerals, the filling of hydrocarbon and the development of overpressure, (3) overpressure can preserve partial primary pores, (4) overpressure can inhibit the growth of some cements and slow down the destruction of diagenesis on deep reservoir, and (5) overpressure can generate some secondary pores by enhancing dissolution.