川东北地区中—上二叠统层序地层格架内多重地质事件耦合的富有机质页岩成因模式  

Organic-rich Shale Genesis Model Coupled with Multiple Geological Events in Middle-upper Permian Sequence Stratigraphic Framework in Northeastern Sichuan

作　　者：陈斐然[1,2] 刘珠江 陆永潮[3] 魏富彬 李飞[1,2] 郭金才 苏泽昕[1,2] CHEN Feiran;LIU Zhujiang;LU Yongchao;WEI Fubin;LI Fei;GUO Jincai;SU Zexin(Research Institute of Geophysics,Exploration Company,China Petroleum&Chemical Corporation,Chengdu 610041,China;State Key Laboratory of Shale Oil and Gas Enrichment Mechanisms and Effective Development,Beijing 102206,China;Resource Institute,China University of Geology(Wuhan),Wuhan 430074,China)

机构地区：[1]中国石化勘探分公司物探研究院,四川成都610041 [2]页岩油气富集机理与高效开发全国重点实验室,北京102206 [3]中国地质大学(武汉)资源学院,湖北武汉430074

出　　处：《地球科学进展》2024年第5期519-531,共13页Advances in Earth Science

基　　金：中国石油化工股份有限公司科技攻关项目(编号:P22136,P23070,P23221)资助。

摘　　要：川东北地区中—上二叠统发育大隆组、吴家坪组二段和茅口组三段3套优质页岩,是继五峰组—龙马溪组之后海相页岩气勘探重要的接替新层系。利用等时地层格架内建立重要地质事件与沉积构造、古环境及古生物之间的对应关系,对川东北地区中—晚二叠世上升流和火山活动等重大地质事件对富有机质页岩发育的影响进行研究。结果表明:①川东北地区茅口组三段—大隆组可划分为5个四级层序,其中TST1、TST3、TST4和TST5体系域为富有机质黑色硅质页岩发育有利层段,明确了中—晚二叠世等时地层格架内火山活动与上升流事件的地质响应特征;②建立了受火山活动和上升流等地质事件共同作用的优质页岩发育模式,明确了茅三段SqPm-2初始拉张期,上升流带来的丰富溶解硅和营养盐等物质,有利于硅藻、硅质海绵和放射虫等生物大量繁殖,为典型上升流—生物耦合发育模式,发育高碳(>10.0%)、高硅(>70.0%)页岩,但厚度相对较薄,具有典型“薄而肥”的特征,是普光地区页岩气勘探亟待突破的有利新层系;吴二段—吴三段SqPw-2快速拉张期,火山活动形成的火山灰携带营养物质有利于有机质的富集,为火山活动—热液富有机质页岩发育模式,页岩总有机碳含量超过4%、硅质矿物含量超过50.0%,但厚度相对较薄,是下一步积极拓展的有利层系;大隆组SqPd-1~SqPd-2拉张鼎盛定型期,基底沉降,上升洋流和热液活动造成硅质生物繁盛,大量有机质在深水缺氧强还原条件下得到良好保存,为上升流—热液富有机质页岩发育模式,优质页岩厚度相对较大(>30 m),具备良好的勘探潜力,是下一步提交页岩气规模储量的有利层系。There exist three sets of quality shale that developed in the Dalong,Wujiangping,and Maokou Formations during the mid-upper Permian,which are important replacements for marine shale gas exploration or the Wufeng Formation-Longmaxi Formation.Based on the relationships between important geological events built on an isochronous stratigraphic framework,sedimentary structures,paleoenvironments,and ancient living organisms,the influence of major geological events,such as middle-late Permian upwelling and volcanic activity,on the development of organic-rich shale in northeastern Sichuan was studied.①It was concluded that the 3rd member of the Maokou-Dalong Formation can be divided into five four-level sequences,among which the systems of TST1,TST3,TST4,and TST5 are favorable for black organic-rich siliceous shale development,and the geological response characteristics of Middle and Late Permian volcanic activity and upwelling events were clarified.②A high-quality shale development model with the combined action of volcanic activity,upwelling,and other geological events was established.It was clear that SqPm-2 represents the initial stage underwent by tectonic extension.The upwelling brought abundant soluble silicon and other nutrients that are favorable for the rapid breeding of organisms such as diatoms,siliceous sponges,and radiolarians.Belonging to a typical coupled developing mode of upwelling and organisms,the shale has high carbon(>10.0%)and silicon(>70.0%)content,whereas the thickness is relatively thin,a typical“thin and high-quality”characteristic,which represents a favorable new layer for shale gas exploration in the Puguang area.SqPw-2 is the state that underwent rapid extension,the tephra that carries abundant nutrients is favorable for organic matter accumulation,belonging to the coupled developing mode of volcanic activity and organisms.The TOC of shale is>4%and siliceous minerals>50.0%,but it is relatively thin,which is favorable for further exploration and expansion.SqPd-1~SqPd-2 is the flourish

关 键 词：川东北地区 中—上二叠统 层序地层 富有机质页岩 火山活动 上升流 

分 类 号：P618.13[天文地球—矿床学]