Analysis of Pool-Forming Factors of the Micangshan Thrust Belt in the Sichuan Basin
WU Shixiang~ 1,2) , TANG Liangjie~ 1,2) , MA Yongsheng~ 3) , GUO Tonglou~ 3) , HUANG Renchun~ 4) , CHENG Shenghui~ 4) , LI Rufeng~ 1,2) , CHEN Meitao~ 1,2) 1) Basin & Reservoir Research Center, China University of Petroluem, Beijing, 102249; 2) Key Laboratory of Education Ministry for Hydrocarbon Accumulation Mechanism, China University of Petroluem, Beijing, 102249; 3) Southern Exploration & Development Company, SINOPEC, Kunming, 650200; 4) Research Institute of Southern Exploration & Development Company, SINOPEC, Kunming, 650200
Foreland basins are one kind of petroleum enrichment basins all over the world. The Sichuan Basin is located in the southwest of China, and on the northern margin of the basin three foreland basins are well developed. Of the three foreland basins, the Micangshan foreland basin is between the Longmen Mountains and the Daba Mountains, which is more poorly developed. With only two small gas fields, the Jiulongshan and Hewanchang gas fields, and Chuanfu 82 and Shejianhe gas-enriched traps have been found in the basin. According to recent seismic survey data along the mountain, many structure traps have been found in the thrust belts in the area, but the key factors in gas pools formation need to be studied. Based on sequence stratigraphy, balanced section analysis, calculation of shorten amount of strata, petroleum generation modeling techniques, in combination of synthetic study of pool forming factors, the paper studies the evolution features of the thrust belt and proposes an evolution mode of Micang Mountain, which indicates that the thrust belt began to evolve from west to east, and the distortion intensity, shortening amount became less from west to east with the evolution. According to systemic studies, the paper pointes out that the pool-forming factors are good, traps are well developed and there is a huge gas potential in the thrust belt. Reservoirs and conservation conditions are the key factors of the formation of pools. The main gas generation layer is Permian rocks. Permian biologic clastic limestone and Triassic oolite are the best reservoirs and the main cover strata are salt rocks in the Leikoupo and Jialingjiang Formations of Triassic.