海相油气地质2017，Vol.22Issue(4)：77-84,8.DOI:10.3969/j.issn.1672-9854.2017.04.010
渝东南地区五峰组—龙马溪组页岩气地球化学特征及其成因分析
Geochemical Features and Genesis of Shale Gas of Wufeng-Longmaxi Formation in Southeastern Chongqing
摘要
Abstract
Wufeng Formation-Longmaxi Formation is an important sequence in Sichuan and Chongqing area for shale gas exploration. Based on the analysis of chemical component and stable carbon isotope composition of the shale gas acquired by desoption experiments on Wufeng-Longmaxi Formation shale cores from the Souteastern Chongqing, it is discussed for the genetic type of shale gas and the reason for alkane carbon isotopic reversal. The results showed that the methane content is high with a value from 94.33% to 98.96% in Longmaxi Formation shale gas, and the non-hydrocarbon content is low, mainly including N2 and CO2. The drying coefficient is more than 0.98, indicating typical dry gas. The values of carbon isotopes of methane and ethane are -49℅~-24.47℅ and -39.4℅~-29℅ respectively, and the carbon isotopes of C1 to C3 alkane in Well Y1 with good gas-bearing presents complete reversal, but Well Y2 presents normal. According to the statistical criteria,natural gas in the Southeastern Chongqing area is derived from the sapropelic source rocks, which is a result of high-temperature pyrolysis. It is a mixing product of pyrolysis of kerogens and secondary pyrolysis of crude oil,with obvious features of secondary pyrolysis of oil. The reason for complete reversal of carbon isotopic in Well Y1 is the mixing of two gases. Perhaps, it has some relationships with high production of shale gas.关键词
五峰组/龙马溪组/气体组分/稳定碳同位素/成因类型Key words
Gas composition/Stable carbon isotope/Genetic type/Wufeng Formation/Longmaxi Formation/Southeastern Chongqing分类
能源科技引用本文复制引用
汪生秀,焦伟伟,方光建,王飞,张志平,王巧丽..渝东南地区五峰组—龙马溪组页岩气地球化学特征及其成因分析[J].海相油气地质,2017,22(4):77-84,8.基金项目
本文受国家科技重大专项项目"下古生界页岩有机质成熟度、类型及结构分析方法研究"(编号:2016ZX05034003-001),重庆市国土资源和房屋管理局科技项目"渝东北下寒武统页岩气吸附解析模型及应用研究"(编号:KJ-2015013)、"渝东北南北相区下寒武统页岩气富集条件对比及有利区优选"(KJ-2015014),重庆市社会事业与民生保障科技创新专项"富水断裂裂缝系统分布综合预测新技术研究与应用"(编号:cstc2017shmsA90003)联合资助 （编号:2016ZX05034003-001）
