石油实验地质Issue(4)：418-422,429,6.DOI:10.11781/sysydz201504418
川西坳陷中三叠统雷口坡组四段气藏气源分析
Source of gas reservoirs in the fourth member of the Middle Triassic Leikoupo Formation in Western Sichuan Depression
摘要
Abstract
A set of thick charcoal grey dolomicrite and micrite source rocks developed in the Middle Triassic Leikoupo Formation in the Western Sichuan Depression, in addition to four sets of marine source rocks in the Permian and its underlying strata. The gas generation intensity of the source rocks is about (1-4)×109 m3/km2, showing a good potential for medium or giant gas fields. According to the gas composition, carbon and hydrogen isotopes, reservoir bitumen and migration conditions, the major sources for the gas reservoirs of the fourth member of the Leikoupo Formation vary in different tectonic zones in the Western Sichuan Depression. The gas from well PZ1 in the Longmenshan piedmont tectonic zone displays high H2 S content, high δ13 C2 value (-26. 4‰) , positive alkane carbon isotopic series and lightδD1 value (-140‰) , consistent with characteristics of mixed gas. The thermal evolution degree reflected by natural gas compositions and carbon isotopes falls between those of Permian and Leikoupo source rocks, which indicates that the gas was sourced from both of them, and the deep faults in front of the Longmenshan Mountains provide favorable conditions for gas migration and accumulation from the source rocks. Meanwhile, the gases from well CK1 in the Xinchang tectonic zone display trace to moderate H2 S content, low δ13 C2 value (-33.2‰) , partial reversal of alkane carbon isotopic series and a light δD1 value (-147‰) , consistent with oil⁃type gas. The thermal evolution degree reflected by natural gas compositions and carbon isotopes is similar to that of Leikoupo source rocks, which indicates that the gases were mainly from the interior source rocks of the Leikoupo Formation.关键词
烃源岩/天然气/雷口坡组/川西坳陷/四川盆地Key words
source rock/natural gas/Leikoupo Formation/Western Sichuan Depression/Sichuan Basin分类
能源科技引用本文复制引用
谢刚平..川西坳陷中三叠统雷口坡组四段气藏气源分析[J].石油实验地质,2015,(4):418-422,429,6.基金项目
国家科技重大专项（2011ZX05005－001）资助。 （）
