川东红星地区二叠系页岩硅质成因及其地质意义OA
Silica genesis and geological significance of the Permian shales in Hongxing area,eastern Sichuan Basin
硅质矿物的成因类型对页岩储集层的品质具有差异化控制作用,但现有储集层评价体系多以石英总量为参数,忽视了不同成因硅质的储集层效应差异.以川东红星地区二叠系吴家坪组二段(吴二段)和茅口组四段(茅四段)页岩为对象,综合应用扫描电镜—能谱分析、X射线衍射和主微量元素测试等方法,系统开展了 2段地层的硅质来源判别、成因及其地质意义探讨.结果表明:(1)红星地区吴二段和茅四段均发育碎屑石英和以放射虫来源为主的生物成因石英(结构保存型与结构改造型),热液成因硅质缺失;在吴二段硅质中,碎屑硅绝对含量为21.7％,生物硅绝对含量为21.22％,为碎屑—生物混合来源,而茅四段以生物硅为主导(20.71％),碎屑硅含量极低(3.34％).(2)提出了 2种硅质的差异富集模式,其中吴二段为深水陆棚相,兼具陆源输入与高生产力双重优势,形成"叠加型富集模式",而茅四段碳酸盐矿物极度富集,陆源输入极弱,导致生物硅相对占比被动升高,形成"碳酸盐稀释控制型模式".(3)生物硅含量对页岩有机质富集、孔隙保存和可压裂性均具有正向效应,红星地区吴二段页岩工程靶窗从富有机碳中硅岩相调整为富有机碳高硅岩相后,测试日产气量由11.67×104 m3提高至26.64×104 m3,验证了生物硅含量在"工程甜点"优选中的关键作用.建议完善包括不同成因硅质含量和岩石力学参数的甜点综合评价体系,进一步指导川东二叠系页岩气甜点的精准选层与高效开发.
The genetic type of siliceous minerals exerts differential controls on shale reservoir quality;however,current reservoir evaluation frameworks predominantly employ total quartz content as a proxy,neglecting the distinct reservoir effects associated with silica of different origins.This study systematically investigates the silica origin,genesis,and geological significance of Permian shales from the Wujiaping Formation Member 2(Wu-2 Member)and Maokou Formation Member 4(Mao-4 Member)in the Hongxing area,eastern Sichuan Basin,using an integrated approach combining scanning electron microscopy with energy-dispersive spectroscopy(SEM-EDS),X-ray diffraction(XRD),and major-trace element geochemistry.The key findings are as follows:(1)Both members contain detrital quartz and biogenic quartz-the latter encompassing structurally preserved(radiolarian fossils)and structurally recrystallized(microcrystalline quartz aggregates)varieties-while hydrothermal silica is absent.The Wu-2 Member is characterized by mixed detrital-biogenic silica(absolute detrital silica content:21.7％;absolute biogenic silica content:21.22％),whereas the Mao-4 Member is dominated by biogenic silica(absolute content 20.71％)with negligible detrital input(absolute content 3.34％).(2)Two contrasting silica enrichment models are proposed:a"superimposed enrichment model"for the Wu-2 Member,where deep-water shelf conditions sustained both substantial terrigenous supply and elevated bioproductivity;and a"carbonate dilution-controlled model"for the Mao-4 Member,where pervasive carbonate minerals accumulation overwhelmingly diluted siliceous components,passively elevating the relative proportion of biogenic silica.(3)Biogenic silica content serves as positive effects for evaluating organic matter enrichment,pore preservation,and reservoir fracability.Shifting the target window in the Hongxing area from carbon-rich,medium-silica lithofacies to carbon-rich,high-silica lithofacies increased daily test gas production from 11.67×104m3 to 26.64×104m3,demonstrating the pivotal role of biogenic silica content in engineering sweet-spot selection.A comprehensive evaluation framework integrating different genetic silica content and rock mechanical parameters is therefore recommended to guide precise layer selection and efficient development of Permian shale gas in the eastern Sichuan Basin.
高山林;李雄;刘皓天;王惠君
中国石油化工股份有限公司油田勘探开发事业部,北京 100728中国石油化工股份有限公司江汉油田分公司,湖北潜江 433124中国石油化工股份有限公司江汉油田分公司,湖北潜江 433124中国石油化工股份有限公司江汉油田分公司勘探开发研究院,湖北武汉 430223
天文与地球科学
硅质来源硅质成因生物硅储集层可压裂性页岩二叠系四川盆地
silica originsilica genesisbiogenic silicareservoir fracabilityshalePermianSichuan Basin
《古地理学报》 2026 (3)
918-933,16
国家科技重大专项(编号:2025ZD1400403)、中国博士后科学基金项目(编号:2024M753623)和中石化科技项目(编号:P24050)共同资助.[Co-funded by the Major National Science and Technology Project of China(No.2025ZD1400403),the China Postdoctoral Science Foun-dation(No.2024M753623),and the Sinopec Science and Technology Project(No.P24050)]
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