Title: Origin and carbon isotope geochemistry characteristics of middle-shallow natural gas in the middle part of Western Sichuan Depression
Abstract: The middle part of Western Sichuan Depression is one of the major gas-producing areas in Sichuan Basin. However, there still exist some different opinions on the genesis and origin of middle-shallow natural gas in this area. In order to get a better understanding of the issues, the authors selected 56 gas samples and analyzed their carbon isotope compositions of C1 -C4, which were collected from producing wells in Xiaoquan-Xinchang-Hexingchang, Luodai-Xindu and Majing gas fields, and analyzed the origin of the middle-shallow natural gas combining with the natural gas composition and the source rock geochemistry characteristics. The population distribution of the methane carbon isotopes indicates a normal pattern of δ13C1 δ13C2 δ13C3 δ13C4. And the carbon isotopes show an obvious decrease vertically from the deeper Xu 4 member, Shaximiao, Suining and Penglaizhen formations until the shallower Lower Cretaceous gas reservoirs, reflecting the origin and migration characteristics of the natural gas. By means of calculating differences between δ13C2 and δ13C1, it could be concluded that the gas maturity increases from deep to shallow. In addition, the paper illustrated that the natural gas of Shaximiao, Suining and Penglaizhen formations in the study area behaves a type of pyrolysis gas and are mainly from Xu 5 and Xu 4 members, partly from Ziliujing Formation.
Publication Year: 2011
Publication Date: 2011-01-01
Language: en
Type: article
Access and Citation
Cited By Count: 4
AI Researcher Chatbot
Get quick answers to your questions about the article from our AI researcher chatbot