河北地质大学学报2026，Vol.49Issue(2)：58-68,94,12.DOI:10.13937/j.cnki.hbdzdxxb.2026.02.007
基于碳氢同位素的深层煤岩气成因分析及沉积环境响应
Deep Coal Gas Genesis Analysis and Sedimentary Environment Response Based on Hydrocarbon Isotopes:A Case Study of Longtan Formation in Western Chongqing
摘要
Abstract
In recent years,significant natural gas showshave been encountered in the deep coal measures of the Permian Longtan Formation in the western Chongqing area,preliminarily confirming considerable resource potential for deep coal-measure gas in this interval.To reveal the geochemical characteristics and clarify the genetic type and origin of the deep coal-measure gas in this region,studies were conducted on the composition of natural gas and the carbon and hydrogen isotopic characteristics of methane,ethane,and CO2.The research results indicate:1)The Longtan Formation coal-measure gas in western Chongqing is predominantly CH4,accompanied by minor CO2 and N2,with low heavy hydrocarbon content.Compared to Permian coal-measure gas from adjacent areas of the Yangtze Platform,the N2 and CO2 contents are significantly higher,indicating a high thermal evolution degree of the coal measures and favorable preservation conditions.2)The carbon isotopes of alkane gases suggest that the deep coal-measure gas is over-mature cracked gas.Hydrocarbon generation history and thermal history analyses indicate that the main gas accumulation in the study area formed during the Early Cretaceous,representing an early charging and accumulation event.3)The δD1 values of the coal-measure gas in the study area exhibit a gradual decrease from bottom to top,a pattern closely related to sea-level fluctuations and paleoclimate variations during the coal deposition period.Spatially,δD1 values in the eastern Sichuan region show an increasing trend from southwest to northeast,overall controlled by the depositional environment and also influenced by the degree of thermal evolution.Under similar thermal evolution conditions,marine δD1 values are more negative than terrestrial values,while the marine-continental transitional facies exhibit a broader range of values.The study demonstrates that the geochemical characteristics of coal-measure gas are closely linked to the formation and evolution of the coal seams,providing a scientific basis for selecting favorable targets and assessing resource potential.关键词
深部煤岩气/碳氢同位素/天然气组分/热演化/沉积环境Key words
deep coal-measure gas/C-H isotope/natural gas composition/thermal evolution/depositional environment分类
天文与地球科学引用本文复制引用
汪小龙,陈志鹏,尹菲,谢鹏辉,柏锦浩..基于碳氢同位素的深层煤岩气成因分析及沉积环境响应[J].河北地质大学学报,2026,49(2):58-68,94,12.基金项目
国家自然科学基金(42102177) （42102177）
