湖相混积砂岩成岩—孔隙演化及致密油意义——以川中龙岗地区侏罗系大安寨段为例  

Diagenesis pore evolution and tight oil significance of lacustrine mixed sandstone:A case study of the Jurassic Da'anzhai section in Longgang area,central Sichuan

作　　者：曹娟 刘小洪[1] 冯明友[1] 张本健 张超 石新 王兴志[1] 祝海华[1] CAO Juan;LIU Xiaohong;FENG Mingyou;ZHANG Benjian;ZHANG Chao;SHI Xin;WANG Xingzhi;ZHU Haihua(School of Geoscience and Technology,Southwest Petroleum University,Chengdu 610500,China;Research Institute of Erploration and Development,Southwest Oil&Gasfield Company,Chengdu 610041,China;CCDC Geological Erploration and Development Research Institute,Chengdu 610051,China)

机构地区：[1]西南石油大学地球科学与技术学院,四川成都610500 [2]中国石油西南油气田分公司勘探开发研究院,四川成都610041 [3]中国石油集团川庆钻探工程有限公司地质勘探开发研究院,四川成都610051

出　　处：《天然气地球科学》2025年第2期322-334,共13页Natural Gas Geoscience

基　　金：国家科技重大专项“大型地层油气藏形成主控因素与有利区带评价”(编号:2017ZX05001-001);中国石油—西南石油大学创新联合体科技合作项目(编号:2020CX050103)联合资助。

摘　　要：湖相混积砂岩多具层薄、细粒、强胶结及互层明显等特征。川中地区侏罗系自流井组大安寨段中上部发育混积砂岩,其储集空间发育程度及勘探潜力尚不明确。为厘清混积砂岩成岩演化及储层改造效应,综合岩石学及元素地球化学等分析测试开展系统研究。结果表明,龙岗地区大安寨段混积砂岩历经早成岩阶段及中成岩阶段的复杂成岩作用改造。其中,主要建设性成岩作用为中成岩阶段早期的酸性流体溶蚀作用及早成岩阶段晚期生排烃伴生的破裂作用;破坏性成岩作用为压实/压溶作用及各成岩阶段形成的黏土矿物、石英、白云石、与油气生成伴生的CO_(2)大量富集相关所致的方解石等胶结物的胶结作用。川中侏罗系大安寨段混积砂岩总体较致密,未完全充填的裂缝、铁方解石微溶孔及高岭石晶间孔隙相对较发育,可作为一定的储集空间。研究结果可为致密油勘探中有利层段的优选提供支撑。Mixed sandstones in lacustrine are characterized as thin layer,fine grain size,intense cementation and interlayer,these are found in the upper part of the Da'anzhai section of the Jurassic Ziliujing Formation in the Longgang area of the central Sichuan Basin.However,the degree of reservoir space development and exploration potential of these sandstones is unclear.To clarify the diagenesis and reservoir modification,a comprehensive study was conducted using petrology and geochemistry.The results indicate that the Da'anzhai mixed sandstones in central Sichuan Basin underwent modification during the early and middle stages of diagenesis.Constructive diagenesis is mainly caused by the three stages of acid fluid promotion of pore/fracture formation,organic acid dissolution of clay mineral impurities to form granular quartz,and fracturing caused by overpressure of fluid associated with hydrocarbon generation and expulsion,and recrystallization.Destructive diagenesis involves physical/chemical compaction and the filling of pores/fractures with cementitious materials such as clay minerals,quartz enlarged edges,dolomite,and calcite associated with the enrichment of CO_(2),in various diagenetic stages.Although the Da'anzhai mixed sandstone in central Sichuan Basin is generally dense,the incomplete filling of fractures,dissolution of micro-pores,and intercrystalline pores contribute to the relative porous reservoirs.This research can provide support for the optimization of favorable intervals in tight oil exploration.

关 键 词：侏罗系 大安寨段 混积砂岩 成岩作用 孔隙演化 酸性流体 

分 类 号：TE122.2[石油与天然气工程—油气勘探]