Gas geochemistry characteristic of shale gas in Longmaxi Formation, SE Sichuan Basin, China

International Conference on Energy Engineering and Environmental Protection 2016

能源学;生态环境科学

Cao, Chunhui^1,2 ; Du, Li^1 ; Li, Liwu^1 ; He, Jian^1 ; Li, Zhongping^1

Key Laboratory of Petroleum Resources, Gansu Province/Key Laboratory of Petroleum Resources Research, Institute of Geology and Geophysics, Chinese Academy of Sciences, Lanzhou

730000, China^1

Key Lab of Mineral Resources in Western China (Gansu), School of Earth Sciences, Lanzhou University, Lanzhou

730000, China^2

关键词: Continuous monitoring;    Crustal materials;    Endogenic process;    Gas geochemistry;    Maturity stages;    Molecular compositions;    Stable carbon isotope compositions;    Thermal destruction;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/52/1/012009/pdf
DOI  :  10.1088/1742-6596/52/1/012009

学科分类：环境科学（综合）

来源: IOP

【 摘 要 】

Shale gas samples collected from Lower Silurian Longmaxi Formation of Southern Sichuan Basin in Weiyuan were analysed for stable isotope composition of noble gases and molecular composition, stable carbon isotope composition of hydrocarbons. Results show these shale gases are of organic origin gas, and produced at high-over maturity stage. All the analysed hydrocarbon gases reveal complete inversed isotopic trends from methane to propane, and δ13C1, δ13C2have obviously different between Weiyuan and Changning areas. CO2was mainly generated during thermogenic processes of transformation of organic matter, although some gases can contain components from endogenic processes and from thermal destruction of carbonates. He and Ar are mainly product of α-decay of U and Th enriched in crustal materials. A small contribution of mantle origin He was found in the gas reservoirs. Continuous monitoring data indicate3He/4He ratio didn't change with the mining time.