四川盆地北部中二叠统茅口组孤峰段优质烃源岩特征及其油气地质意义  

Characteristics and petroleum geological significance of the high-quality source rocks in the Gufeng Member of the Middle Permian Maokou Formation in the northern Sichuan basin

作　　者：付小东 陈娅娜 罗冰[3] 李文正 张建勇 王小芳 邱玉超[3] 吕学菊 姚倩颖 FU Xiaodong;CHEN Yana;LUO Bing;LI Wenzheng;ZHANG Jianyong;WANG Xiaofang;QIU Yuchao;LüXueju;YAO Qianying(PetroChina Hangzhou Research Institute of Geology,Hangzhou,Zhejiang 310023,China;Research Institute of Sichuan Basin,Petrochina Research Institute of Petroleum Exploration&Development,Chengdu,Sichuan 610041,China;PetroChina Southwest Oil Gas Field Company,Chengdu,Sichuan 610051,China)

机构地区：[1]中国石油杭州地质研究院,浙江杭州310023 [2]中国石油勘探开发研究院四川盆地研究中心,四川成都610041 [3]中国石油西南油气田分公司,四川成都610051

出　　处：《地质学报》2021年第6期1903-1920,共18页Acta Geologica Sinica

基　　金：“十三五”国家油气专项(编号2017ZX05008005);中国石油天然气股份有限公司重点科技项目(编号2018A-0105);中国石油西南油气田分公司四川盆地勘探重大项目(编号XNS14NH2019-005)联合资助的成果。

摘　　要：二叠系是四川盆地海相烃源岩发育的重要层系,对天然气勘探具有重要意义。基于钻井、测井与露头剖面资料综合分析,厘定了四川盆地北部重点钻井中二叠统与上二叠统界线,证实在盆地北部广泛发育茅口组孤峰段薄层状碳硅泥岩,揭示了孤峰段优质烃源岩分布、地球化学特征与发育环境,评价了其生烃潜力及成藏贡献。结果表明:①四川盆地北部孤峰段优质烃源岩厚度在5~40m,呈北西-南东向带状展布,存在4个厚值区;②孤峰段烃源岩TOC整体极高、变化范围大,分布在0.5%~31.04%,均值5.08%,为一套优质烃源岩,有机质类型主要为Ⅱ型,有机质成熟度处于成熟—过成熟阶段;③拉张构造背景下形成的台内裂陷深水沉积环境、强还原条件与高古生产力共同控制了孤峰段优质烃源岩发育与分布;④孤峰段优质烃源岩生烃潜力较大,生烃强度主要在5×10^(8)~25×10^(8)m^(3)/km^(2),对研究区内海相常规天然气和页岩气勘探均具有重要意义。Permian is an important stratum for the development of marine source rocks in the Sichuan basin,which is of great significance for natural gas exploration.Based on the comprehensive analyses of wells,logging and outcrop data,the stratigraphic boundary between the Middle Permian and Upper Permian in the key wells in the northern Sichuan basin has been redefined.It is confirmed that thin-layer carbonaceous and siliceous mudstone in the Gufeng Member of the Middle Permian Maokou Formation is developed widely in the northern Sichuan basin.Through systematic sampling and analysis of wells and outcrops,the thickness distribution,geochemical characteristics and control factors of high-quality source rocks in the Gufeng Member are identified,and their hydrocarbon generation potential and contribution to gas reservoir formation are evaluated.The results show that:①the thickness of the high-quality source rocks in the Gufeng Member is mainly 5~40m,which is in the NW-SE zonal distribution in the northern Sichuan basin,and there are four thickness centers.②The TOC of the source rock in the Gufeng Member is extremely high and varies widely,ranging from 0.5%to 31.04%,with an average value of 5.08%,indicating it to be a high-quality source rock.The type of organic matter is mainly type II,and the maturity of organic matter is in the stage of maturity over maturity.③The deep-water sedimentary environment,strong reducing conditions and high paleoproductivity of the rifted depression in the platform against the background of extensional structure jointly control the development and distribution of highquality source rocks in the Gufeng Member.④The high-quality source rocks in the Gufeng Member have great potential for hydrocarbon generation,with the hydrocarbon generation intensity mainly distributed over 5×10^(8)~25×10^(8)m^(3)/km^(2),reaching the standard of forming large and medium-sized gas fields.The high-quality source rocks in the Gufeng Member are of great significance for the exploration of marine conventional n

关 键 词：优质烃源岩 孤峰段 茅口组 四川盆地北部 

分 类 号：P618.13[天文地球—矿床学]