早石炭世断陷盆地构造特征及演化规律与页岩气保存关系:以桂中坳陷融水地区为例  

Relationship between structure and evolution of the Early Carboniferous rifted basin and shale gas preservation:A case study of the Rongshui area in the Guizhong Depression

作　　者：岑文攀 覃英伦 王祥 熊伟伟 黄文芳 卓色强 CEN Wenpan;QIN Yinglun;WANG Xiang;XIONG Weiwei;HUANG Wenfang;ZHUOSeqiang(Guangxi Institute of Geological Survey,Nanning 530023,China;Key Laboratory of Tectonics and Petroleum Resources of the Ministry of Education,China University of Geosciences(Wuhan),Wuhan 430074,China;Guangxi Energy Group Co.,Ltd.,Nanning 530000,China;School of Earth Sciences,China University of Petroleum(Beijing),Beijing 102299,China;Guangxi Liuzhou Power Generation Co.,Ltd.,Liuzhou Guangxi 545001,China)

机构地区：[1]广西壮族自治区地质调查院,南宁530023 [2]中国地质大学(武汉)构造与油气资源教育部重点实验室,武汉430074 [3]广西能源集团有限公司,南宁530000 [4]中国石油大学(北京)地球科学学院,北京102299 [5]广西柳州发电有限公司,广西柳州545001

出　　处：《地质科技通报》2024年第4期39-52,共14页Bulletin of Geological Science and Technology

基　　金：广西能源集团项目(LD-2022-117);广西科技厅重点研发计划项目(2021AB30011);广西地矿局科研项目(桂地矿综研[2023]13号,GXDK202430);广西关键矿产资源深部勘查人才小高地(2019085);广西国资委核心科技攻关和重大科技创新项目(2060404)。

摘　　要：广西页岩气勘探已在雪峰山隆起南缘桂中坳陷中北部的下石炭统鹿寨组取得多处页岩气重要发现,商业试采取得出气点火成功,但该地区坳陷内结构及演化特征尚未明确,制约了对富有机质泥页岩形成条件与有利沉积相带展布特征、页岩气富集规律的准确认识。以融水地区为例,通过地质调查分析、二维-三维地震剖面构造解译及演化平衡剖面等技术,对主要构造及结构特征、构造演化规律及其与页岩气保存关系进行研究,认为研究区现存3条主干断裂、NE-NNE向4个主要向斜构造,先存的NNE向三江-融安断裂是伸展断陷、挤压-走滑改造作用的主控因素。研究区在寒武系褶皱基底上,伸展断陷发展于晚泥盆世、强盛于早石炭世早期、停止于早石炭世晚期,坳陷改造期的挤压-走滑作用发育于印支期、燕山期,喜山期局部张性作用。现今的褶皱体系主体形成于印支期,受自西向东三江融安断裂的逆冲作用逐渐增强的影响,呈现宽缓向斜-复式向斜-断展褶皱的构造样式展布规律。沙坪复式向斜是页岩气保存的有利构造单元,页岩气保存有利的构造样式为断向斜、断背斜。该认识明确了该地区下一步页岩气勘探部署的方向,为桂中坳陷中北部的环江浅凹等结构和演化认识提供有利思路。[Objective]Many important discoveries have been made in shale gas exploration in the Lower Carboniferous Luzhai Formation in the central and northern Guizhong Depression,southern margin of the Xuefengshan Uplift,and commercial test production has achieved successful gas ignition.However,the structure and evolution of the depression in this area have not been clearly defined,which restricts an accurate understanding of the formation conditions for organic-rich mud shale,the distribution of favourable sedimentary facies zones,and shale gas enrichment law.[Methods]Taking the Rongshui area as an example,this paper studies the main structures and their relationships with shale gas preservation through geological investigation and analysis,2D-3D seismic section structural interpretation,evolutionary equilibrium section interpretation and other technologies.[Results]It is believed that there are three main faults and four main NE-NNE synclines in the study area.The preexisting NNE-trending Sanjiang-Rong′an fault is the main factor involved in extensional fault depression and compression-strike-slip transformation.In the study area,the extensional fault depression developed in the Late Devonian,strengthened in the Early Carboniferous and stopped in the late Early Carboniferous.The compression-strike-slip effect of the depression reconstruction developed in the Indochinese and Yanshanian stages,and the local tensioning effect developed in the Alpine stage.The main part of the present fold system was formed in the Indosinian period.Influenced by the increasing thrust of the Sanjiang-Rong′an fault from west to east,the structure pattern of broad and slow synclinal-compound synclinal-faulted folds is distributed.Complex synclines are favourable structural units for shale gas preservation,and the favourable structural styles for shale gas preservation are synclines and anticlines.[Conclusion]This understanding clearly defines the direction of shale gas exploration and deployment in the next step,and provides a beneficial

关 键 词：早石炭世 断陷盆地 构造演化 桂中坳陷 页岩气保存 沙坪复式向斜 

分 类 号：P618.13[天文地球—矿床学]