Difference of subsidence history and its influence on reservoir porosity in Kuqa Depression
Han Zhirui1, Zeng Lianbo1, Gong Lei1, Zhu Rukai2, Gao Zhiyong2
1. College of Geosciences, China University of Petroleum, Beijing 102249;
2. State Key Laboratory of Enhanced Oil Recovery, Research Institute of Petroleum Exploration & Development, PetroChina, Beijing 100083
We analyze and contrast the subsidence history of typical wells in the eastern section and the western section of Kuqa Depression with the principle of backstripping and basin modeling technology. In Kelasu structural belt,the subsidence curve reveals that the stratum is buried deep at the early stage and continues to be buried deep at the late stage. In Qiulitage structural belt,the buried stratum is shallower early compared with the stratum of Kelasu structural belt while it becomes deeper late. In Forebulge structural belt,the subsidence curve shows that the buried stratum is shallow early and remains shallow late. The distinct strength of tectonic movement and the visible difference of subsidence history lead to the different porosity between different structural belts in Kuqa Depression. The difference of subsidence history suggests that burial time and burial depth decrease from Kelasu structural belt to Forebulge structural belt,which leads to the decline in the pressure of reservoirs during burial history. Owing to those,the compaction intension of reservoirs decreases from Kelasu structural belt to Forebulge structural belt,leading to the porosity increasing from north to south. Time-depth index can quantitatively reflect the difference of subsidence history and its influence on the porosity.