Characteristics of formation pressure and its significance for the subsalt deep layer in foreland thrust belt of Kuqa depression
Wang Xiang1, Li Yong1, Lü Xiuxiang2, Wang Yuan1, Zhou Lu1, Zhuo Qingong3, Shang Jiangwei1
1. Research Institute of Petroleum Exploration and Development, Tarim Oilfield Company, CNPC, Korla, Xingjiang 841000;
2. School of Earth Sciences, China University of Petroleum, Beijing 102249;
3. Research Institute of Petroleum Exploration and Development, CNPC, Beijing 100083
The gas reservoirs with deep burial developed high formation pressure. Large amount of tested pressure data were collected and formation pressure framework and distribution were analyzed, and revealed their relationships with gas reservoirs. The results showed that the values of formation pressure and pressure coefficient are 85~127 MPa and 1.5~1.9, respectively. Pressure and pressure coefficient both displayed features of different zones in north and south, different parts in east and west. The top distance between Jurassic source rock and Cretaceous Bashenjiqike sand is 1 500~4 000 m, averaging 3 000 m, the pressure difference between source rock and reservoirs is over 70 MPa, which provided the dynamical conditions for gas charging strongly and forming gas reservoir efficiently. Distribution of high formation pressure and subsalt deep large gas field superimposed in the plane, and vertically gas reservoir group distributed as a row and belt shape, locating in the thrust wedge with high formation pressure.