摘要
川中广安气田是四川盆地2006年新发现的上报探明地质储量超过500×108m3的大型气田,也是目前四川盆地在上三叠统产层发现的最大气田。由于广安气田所在地区上三叠统烃源岩的生气强度小于20×108m3/km2,不具备形成大中型气田的理想条件,因此该气田的天然气成因类型及气源成为一个亟待解决的问题。笔者通过对广安气田天然气组分和碳同位素等资料的详细分析,判定其天然气为煤成气;根据气源对比,排除了下伏和上覆烃源岩的供源可能性,证实广安气田为上三叠统须家河组煤系地层自生自储形成。最后,经过对天然气运移途径分析,认为近源侧向运移是形成广安大型气田的主因。
The Guang＇an gasfield is a large one newly discovered in the Sichuan basin in 2006 and has identified reserves of more than 500×108 m^3. It is also the largest gasfield ever discovered in the Upper Triassic strata in the Sichuan basin up to now. Because the gas generation intensity of Upper Triassic hydrocarbon source rocks in the study area is less than 20×10^8m^3/km^2, theoretically, no ideal conditions for the formation of a large or mediumsized gasfield are available in the area, and consequently the genetic type and source of natural gas in the gasfield are a problem that needs urgent solution. An intensive analysis of the components and carbon isotope data of the gas shows that the gas is coal gas. According to a correlation of gas sources, the possibility that the overlying and underlying source rocks provide gas is ruled out. In other words, the formation of the Guang＇an gasfield is due to self-generation and self-accumulation of gas in the coal measures of the Upper Triassic Xujiahe Formation. Finally, an analysis of the gas migration pathway reveals that the proximal lateral migration is the main cause for the formation of the large Guang＇an gasfield.
出处
《中国地质》
CAS
CSCD
2007年第5期829-836,共8页
Geology in China
基金
中国石油天然气股份有限公司科技项目"岩性地层油气藏勘探理论与实践"(040501-09)资助。
关键词
广安气田
上三叠统
碳同位素
天然气成因
气源
Guang＇an gasfield
Upper Triassic
carbon isotope
genesis of natural gas
gas source
