Geochemical Characteristics and Gas-Source Correlation of Leikoupo Formation in Zhongba Field, Northwest Sichuan Basin
详细信息
- 责任者：Liao Fengrong (Research Institute of Petroleum Exploration & Development ; PetroChina ; Beijing 100083 ; China) ; Wu Xiaoqi
- 刊名：Natural Gas Geoscience
- 出版年：2013
- 卷期：24(1)
- 关键词：天然气 ; natural gas ; 油—源对比 ; oil-source rock correlation ; 四川盆地 ; Sichuan Basin
- 页码：p.108-115
- 图表：illus., 1 table, 39 refs.
- 分类号：1003
- issnNo：ISSN1672-1926
- isbnNo：CN62-1177/TE
摘要
There are two main natural gas pay zones in the Zhongba gas field,that is,Member 2 of Xujiahe Formation,Upper Triassic(T3x2) and Member 3 of Leikoupo Formation,Middle Triassic(T2l3) in the northwest Sichuan basin.The gas source for T2l3 remains controversial.The paper analyzes the components as well as carbon and hydrogen isotopic composition characteristics of gases from T2l3.To compare with the gases from the Leikoupo Formation,the paper also selects the gases from Member 2 of the Upper Triassic Xujiahe Formation in Zhongba gas field,the Permian Maokou Formation and the Changxing Formation as well as the Lower Triassic Feixianguan Formation in the Hewanchang gas field and the Feixianguan Formation in the northeastern Sichuan basin.Gases from the Leikoupo Formation display high gas dryness index around 0.97,high H2S and CO2 contents.Gases from the Leikoupo Formation and the Xujiahe Formation of the Zhongba field,the Hewanchang field and the Feixianguan Formation in the northeastern Sichuan basin display great differences in carbon and hydrogen isotopic composition characteristics.The ethane carbon isotopic values of the Leikoupo Formation are heavier than those of the Hewanchang gas field and the Feixianguan Formation in the northeastern Sichuan basin,but the methane carbon isotopic values are lighter than those of the Feixianguan Formation.The methane hydrogen isotope of the Leikoupo Formation are about-140‰,20‰ lower than those of the oil-associated gases of the Feixianguan Formation,but 30‰ greater than those of the coal-derived gases of the Xujiahe Formation.Comprehensive analysis about gas components,carbon and hydrogen isotopic composition characteristics,light hydrocarbon compositions,Mercury contentssuggested that gases from the Leikoupo Foramation of the Zhongba field are mainly Permian oil-associated gases mixed with a proportion of coal-derived gases from the Xujiahe Formation,and experienced thermochemical sulfate reduction transformation.