煤田地质与勘探2025，Vol.53Issue(6)：70-83,14.DOI:10.12363/issn.1001-1986.25.09.0489
川东南地区不同构造样式页岩气中氦气差异富集机理
Mechanisms underlying differential helium enrichment in shale gas of varying structural styles in the southeastern Sichuan Basin
摘要
Abstract
[Objective]Shale gas reservoirs hold considerable helium reserves despite relatively low helium abundance,establishing them as a critical replacement for helium production growth.The southeastern Sichuan Basin exhibits di-verse structural styles with varying preservation conditions,leading to an unclear understanding of the distribution char-acteristics and enrichment patterns of helium in shale gas.Determining the mechanisms behind the differential helium enrichment in shale gas is significant for the effective utilization of helium in shale gas.[Methods]Focusing on the typ-ical shale gas reservoirs of different structural styles in the southeastern Sichuan Basin,this study explored the mechan-isms underlying differential helium accumulation in shale gas in different structural styles and determined the potential play fairways for the exploration of helium in shale gas.[Results and Conclusions]The Wulong residual syncline,Baima fault-fold deformation zone,and the shallowly buried Dingshan faulted anticline,featuring unfavorable structural preservation conditions and normal formation pressure,have relatively high helium abundance,averaging 524×10-6,606×10-6,and 534×10-6,respectively and reaching the industrial helium extraction standards.In contrast,the Jiaoshiba broad gentle anticline,Baima syncline,and deeply buried Dingshan faulted anticline,with favorable structural preserva-tion conditions and formation overpressure,show relatively low helium abundance,averaging 335×10-6,381 ×10-6,and 250×10-6,respectively.The shale gas in the Wufeng-Longmaxi formations of different structural styles in the southeast-ern Sichuan Basin primarily holds crust-derived helium,exhibiting great helium-generating potential.However,shales of different structural styles show nonsignificantly different helium-generating potential.The calculations of helium pro-duction based on the uranium and thorium decay theories,as well as the helium and argon isotope analyses,demonstrate that the helium in shale gas reservoirs in the southeastern Sichuan Basin is primarily of an endogenous origin,suggest-ing self-sourced helium reservoirs.The differences in shale gas dilution intensity,caused by the differential preservation conditions of different structural styles and resulting differential dissipation behavior of the shale gas-helium system,serve as a key factor in helium accumulation of varying structural styles in the southeastern Sichuan Basin.Additionally,the synergistic effects of the diffusion and enrichment effects of helium in micro/nano pores and the physical clogging of migration pathways with methane molecules are identified as another significant factor governing helium enrichment in shale gas.Based on the investigation of the mechanisms behind helium enrichment in shale gas of different structural styles in the southeastern Sichuan Basin,it is predicted that secondary low-pressure zones with low shale gas grades out-side the basin-such as the Qijiang,Wulong,Baima,and Pengshui blocks-are potential play fairways for helium en-richment in shale gas.This study is expected to open up an entirely new direction for the exploration and production of helium in shale gas.关键词
氦气/页岩气/川东南地区/构造样式/保存条件/差异富集Key words
helium/shale gas/southeastern Sichuan Basin/structural style/preservation condition/differential accumu-lation分类
石油、天然气工程引用本文复制引用
辛志源,陈践发,王杰,马勇..川东南地区不同构造样式页岩气中氦气差异富集机理[J].煤田地质与勘探,2025,53(6):70-83,14.基金项目
国家重点研发计划项目(2021YFA0719000) （2021YFA0719000）
国家自然科学基金项目(42173030) （42173030）
中国石化油气成藏重点实验室开放基金课题(33550007-24-ZC0607-0002) （33550007-24-ZC0607-0002）
