论文详情
On Tongnanba structural belt in the northeast Sichuan province, the formations of Yangxin series in lower Permian were found with the basic conditions of developing largescale gas reservoirs. Through analyzing the structural evolution of Tongnanba structural belt, the fault system and its advantages were analyzed. Tongnanba structural belt is a large anticline, and its structural trend is northeast to southwest. Meanwhile, a lot of northwest-southeast faults develop in the main body of structural belt, which cut the main body and build up many subset structures. In the area of Hei-chiliang-Malubei, northeast of Tongnanba structural belt, fault system develops a lot in the Yangxin series, with the properties of multiphase, multi-direction and inter-connected. Through analyzing balanced sections and sequence stratigraphies, some of the faults were found apparently reversal faults. These are extensional normal faults in the early phase and become compressional abnormal faults in the later stage. The large-scale fault system in Tongnanba structural belt is beneficial to the development of fractures, and the property of extensional normal faults in the early phase is beneficial to karstification. Meanwhile, though the faults develop a lot but do not cut across its upper thick gipsmantle, so the preservation condition is relatively good. Combined with the advantage that the formation of lower Permian is good hydrocarbon source rock, the conclusion is obtained that the Tongnanba structural belt is potential prospecting area.