Effects of High Temperature and Overpressure on Reservoir Quality in the Yinggehai Basin, South China Sea

Research into hydrocarbon basins around the world has shown that overpressure is closely connected with hydrocarbon generation and distribution. Because of unique sedimentary sequences and temperature-pressure characteristics, reservoir diagenesis has larruping processes and traits. Through comparing two types of overpressure systems (self-source type and conduction type), confirmed by core and log, this paper illustrates their origin and hydrocarbon value, and sets forth the effects of high temperature and overpressure on reservoir qualities, which include: ① reservoir characteristics are mainly determined by sedimentary environment and diagenesis; ② high geotemperature gradient decreases sandstone porosity; ③ (overpressure) conserves parts of original porosity, which causes high porosity in a deep reservoir; ④ overpressure brings out much of secondary porosity in the processes of diagenesis; ⑤ fluid breakthrough causes cracks, which effectively increase reservoir permeability.