川中地区中二叠统茅口组白云岩储层特征及发育主控因素  

Dolomite reservoirs of the Middle Permian Maokou Formation,central Sichuan Basin:Characteristics and main influential factors

作　　者：山述娇[1] 陈聪[1] 张玺华[1] 谢忱 陈延贵[1] 徐正华 SHAN Shujiao;CHEN Cong;ZHANG Xihua;XIE Chen;CHEN Yangui;XU Zhenghua(Exploration and Development Research Institute,PetroChina Southwest Oil&Gasfield Company,Chengdu,Sichuan 610041,China;Oil and Gas Resources Department,PetroChina Southwest Oil&Gasfield Company,Chengdu,Sichuan 610051,China;Linfen Gas Production Management Zone,PetroChina Coalbed Methane Com-pany Limited,Taiyuan,Shanxi 030000,China)

机构地区：[1]中国石油西南油气田公司勘探开发研究院 [2]中国石油西南油气田公司油气资源处 [3]中石油煤层气有限责任公司临汾采气管理区

出　　处：《天然气勘探与开发》2023年第4期27-34,共8页Natural Gas Exploration and Development

基　　金：中国石油天然气集团有限公司科技项目“风险勘探领域和目标研究、工程技术攻关及现场试验”资助项目(编号:2023YQX10104)。

摘　　要：四川盆地中部地区中二叠统茅口组发育不同程度的白云石化储层,针对该储层的天然气勘探近期获得重大发现,因此储层面貌的表征、白云石化机制的探索及白云岩储层主控因素的把握,对勘探部署具有重要的指导意义。为此,基于岩心和露头样品的宏观、微观观测及地球化学特征分析,对茅口组白云岩储层的特征、成因及主控因素进行研究,结果表明:①川中地区茅口组白云岩储层位于茅二段上部,横向稳定分布,岩性主要为细—中晶残余砂屑云岩、生屑云岩、云质灰岩等,储集类型以白云岩溶蚀孔隙型、白云岩溶蚀缝洞型、石灰岩孔隙型为主;②通过岩石学特征、矿物特征及接触关系,建立成岩序列,共识别出8期成岩作用:同生期暴露溶蚀作用—同生期白云石化作用—浅埋藏期白云石化作用—浅埋藏期硅化作用—东吴期白云石化作用—印支期热液溶蚀作用—印支期热硅化作用—深埋藏期溶蚀作用;③该区茅口组白云岩发育分布受台缘高能滩、早期暴露溶蚀和早期白云石化联合控制,后期热液及埋藏期溶蚀作用有利于改造储层。There developed varying dolomitized reservoirs in the Middle Permian Maokou Formation,central Sichuan Basin,in which significant gas discoveries have been made recently.Thus,the reservoir characterization,the enquiry of dolomitization mechanisms and the identification of main controls are very meaningful tasks for next exploration and deployment.Based on the macroscopic and microscopic observation on cores and outcrop samples,as well as some analysis on geochemical features,the characteristics,genesis and main controlling factors were investigated for the dolomite reservoirs.Results show that(i)these Maokou reservoirs in central basin are developed in the upper Maokou 2 Member,which are featured by stable lateral extension,and they are dominated by fine to medium crystalline residual sand-calstic dolomite,bioclastic dolomite,and dolomitic limestone.And there exist three reservoir types,for example dolomite porous reservoirs,dolomite fractured-vuggy and limestone porous ones;(ii)a diagenetic sequence has been es-tablished according to petrological and mineral characteristics along with contact relationship.Eight diagenetic episodes were identi-fied,including contemporaneous exposure dissolution,contemporaneous dolomitization,shalllow-burial dolomitization,shallow-burial silicification,Dongwu dolomitization,Indosinian hydrothermal dissolution,Indosinian thermal silicification,and deep-burial dissolu-tion;and(iii)for the dolomite reservoirs of Maokou Formation in the study area,both extension and distribution are jointly controlled by platform-margin high-energy beach,early exposure dissolution and dolomitization.Both later hydrothermal dissolution and burial dissolution are conducive to reforming reservoirs.

关 键 词：川中地区 二叠系茅口组 白云岩 成岩序列 同生期暴露溶蚀 白云石化 台缘滩 早期白云石化 

分 类 号：P618.13[天文地球—矿床学]