礁滩相碳酸盐岩岩溶作用及其对孔隙分布的控制——以塔中东部上奥陶统良里塔格组为例  

Karstification of reef-bank facies carbonate rock and its control on pore distribution: A case study of Upper Ordovician Lianglitage Formation in eastern Tazhong area, Tarim Basin, NW China

作　　者：屈海洲[1,2] 王振宇[1,2] 杨海军[3] 张云峰[1,2] 于红枫[3] 王茜[3] 

机构地区：[1]西南石油大学油气藏地质及开发工程国家重点实验室 [2]西南石油大学资源与环境学院 [3]中国石油塔里木油田公司

出　　处：《石油勘探与开发》2013年第5期552-558,共7页Petroleum Exploration and Development

基　　金：国家科技重大专项"塔里木盆地海相碳酸盐岩油气资源潜力;有利勘探区带评价与目标优选"(2011ZX05004-004);四川省重点学科建设项目(SZD0414)

摘　　要：利用岩心、薄片、测井等资料，研究塔中东部地区上奥陶统良里塔格组礁滩相碳酸盐岩的岩溶作用类型、特征及对孔隙分布的控制机理。研究区经历了同生岩溶及早成岩近地表岩溶作用。在良三段-良一段礁滩复合体沉积期，同生岩溶形成具有大量选择性溶蚀孔隙的大气淡水成岩透镜体，发育于各期礁、滩沉积旋回的中上部，单个孔隙（洞）层厚10-30m，可增加3％～4％的绝对孔隙度。沉积期后，沉积物未经历埋藏期成岩作用就抬升、暴露，受到早成岩近地表岩溶作用，沉积地貌转换为岩溶古地貌，在距良里塔格组顶部100m深度内形成了4个岩溶带，表层岩溶带与径流岩溶带孔隙有效性、连通性较好，可增加4％～8％的绝对孔隙度。两种岩溶作用成岩阶段具有连续性、形成的孔隙空间分布具有继承性，良好的时空耦合关系是研究区有效孔隙集中发育在良三段一良一段的关键因素。The karstification type and characteristics and its control on pore distribution in reef-bank carbonate rock in the Upper Ordovician Lianglitage Formation （O31） in eastern Tazhong area were studied using cores, thin sections and well logging data. The area experienced two types of karstification： syndepositional karstification and early diagenetic karstification near surface. During the depositional stage of reef-bank complex, meteoric diagenetic lens with lots of selective dissolution pores were formed by the syndepositional karstification, they were developed in the middle and upper parts of reef-bank sedimentary cycles, and a single porouscavity layer has a thickness of 10-30 m, increasing the absolute porosity by 3%-4%. After depositional stage, sediments were uplifted and exposed without experiencing burial diagenesis, the depositional topography was influenced by early diagenetic karstification near surface and turned into karst paleotopography and formed four karstification zones within 100 m below the top of the Upper Lianglitage Formation. The surface karstification zone and radial flow karsitifiction zone have favorable porous connectivity, increasing the absolute porosity by 4%-8%. These two types of karsitifiction are continuous in diagenesis stage and the formed porosity is successive in distribution. The favorable space-time coupling is the key reason for effective pores being largely developed in the 0313-0311 members.

关 键 词：孔隙分布 岩溶作用 礁滩相 良里塔格组 奥陶系 塔中东部地区 

分 类 号：TE122.1[石油与天然气工程—油气勘探]