PRIMARY STUDY ON THE DYNAMICS OF NATURAL GAS POOLS IN SICHUAN BASIN, CHINA
四川盆地天然气成藏动力学初探

Sichuan superposition basin is one of the main natural gas production areas in China. The dynamics of natural gas pools is the critical studying content about the natural gas exploration in the basin. The upper Triassic Xujiahe formation in west Sichuan basin can be thought as an entire abnormal pressured compartment with natural gas. There are two abnormal pressured fluid compartments in vertical profiles of east Sichuan basin. The first one, called upper abnormal pressured fluid compartment, is located from lower Triassic Jialingjiang formation to Permian system. The second one, called lower abnormal pressured fluid compartment, is located in Silurian system. Carboniferous system is in the middle of the two abnormal pressured fluid compartments. Hydrocarbon-generation is the chief lifting pressure mechanism within compartments. The model of initial migration and expulsion is vertical in the tight clastic reservoir of west Sichuan basin and the carbonate reservoir of east Sichuan basin. The mode is made by the abnormal paleo-overpressure through the crack of abnormal pressured fluid compartments. The abnormal paleo-overpressure was the movement force, which made the adjustment of the fluids and the formation of natural gas reservoir pools within the upper Triassic Xujiahe formation. Buoyancy and hydrodynamics has controlled the formation of the natural gas reservoir pools in east Sichuan basin.