中国地质2025，Vol.52Issue(2)：665-679,15.DOI:10.12029/gc20210816001
湘中坳陷石炭系天鹅坪组富有机质页岩的形成与页岩气富集机理
Mechanism of organic-rich shale formation and shale gas enrichment in the Carboniferous Tian'eping Formation from the Xiangzhong Depression
摘要
Abstract
This paper is the result of oil and gas exploration engineering. [Objective]Through the study of shale formation and shale gas enrichment mechanism,the current study aims at finding out main factor controlling shale gas reservoir in the Carboniferous Tian'eping Formation in the Xiangzhong Depression as well as its enrichment patterns.[Methods]Carbonates carbon and oxygen isotopes as well as shale trace elements and major elements were analyzed at Well Xiangxindi 4 in order to recover paleo-environment and investigate the origin for the shale formation.Combined with the thermal evolution simulation of medium-low maturity shale gas reservoirs,the mechanism for shale gas enrichment is identified through petromineralogy,organic geochemistry,physical properties of shale gas reservoirs,existence forms of shale gas and tectonic preservation condition.[Results](1)The organic-rich shale in Lower Carboniferous Tian'eping Formation were formed due to seawater stratification and seabed anoxia caused by the intensive climatic fluctuations in the Early Carboniferous.(2)The extensive and intense magmatic events in central Hunan led to the increase of locally paleogeothermal gradient and further caused secondary hydrocarbon generation in the Lower Carboniferous organic-rich shale.Shale gas in the Tian'eping Formation was formed owing to crude oil cracking and secondary hydrocarbon generation of organic matter.(3)Shale gas preservation was promoted due to decollement in the Ceshi Formation of the lower Carboniferous blocking the vertical escaping channel of the shale gas from the underlying Tian'eping Formation.[Conclusions]The shale gas of Lower Carboniferous Tian'eping Formation in Xiangzhong Depression is the common result of favorable facies zone controlling the total organic carbon content,magmatic thermogenesis controlling the reservoir physical properties and detachment structure controlling the preservation.关键词
页岩气/富有机质页岩/成因/富集模式/下石炭统/油气勘查工程/湘中Key words
shale gas/organic-rich shale/genesis/enrichment pattern/Lower Carboniferous/oil and gas exploration engineering/Central Hunan Province分类
天文与地球科学引用本文复制引用
陈孝红,石万忠,田巍,何红生,李海..湘中坳陷石炭系天鹅坪组富有机质页岩的形成与页岩气富集机理[J].中国地质,2025,52(2):665-679,15.基金项目
中国地质调查局项目(DD20190558、DD20190559)资助. Supported by the projects of China Geological Survey(No.DD20190558,No.DD20190559). （DD20190558、DD20190559）
