Formation Conditions And Accumulation Rules Of Natural Gas From Sinian To Upper Paleozoic In Northwest Sichuan

Northwestern Sichuan is one of the most important areas for the exploration of marine natural gas in the Sinian Upper Paleozoic of Sichuan Basin.At present,industrial oil and gas flow has been found in Zhongba,Kuangshanliang,Hewanchang,Wujiaba,Jiulongshan,Shuangyushi and other structures.In this paper,the oil and gas accumulation in Northwest Sichuan is studied from the aspects of multi-layer oil source correlation,structural evolution,inclusion characteristics and oil and gas accumulation history Reservoir analysis,focusing on Jiulongshan structure and shuangyushi structure,analyzes the reservoir forming process,summarizes the reservoir forming model of Northwest Sichuan,predicts the favorable oil and gas areas in Northwest Sichuan,hoping to have guiding significance for exploration and production in Northwest Sichuan.The results show that the reservoir forming system is developed in the deep layer,in which the mudstone of the Cambrian Qiongzhusi formation is the source rock,the shale of the Sinian Dengying Formation is the reservoir,and the mudstone of the Cambrian Qiongzhusi formation is the regional cap rock.The Jiulongshan anticline structural belt in Northwest Sichuan is one of the most favorable structural exploration areas.In the middle and deep layers,the Permian carbonate and argillaceous source rocks are the main source rocks,the Permian Qixia Formation and Maokou Formation are the main reservoirs,and the Triassic Jialingjiang formation and Leikoupo Formation gypsum salt rocks are the regional caprock forming systems.The natural gas is mainly self generated and self stored in the Permian system as a whole.Due to the fault communication near the piedmont fault active area,it has part of the contribution of the Cambrian system.Especially in the South and west of pisolite structure.