沉积和成岩作用对湖相重力流致密砂岩储层质量的影响——以鄂尔多斯盆地合水地区长7段为例  

Effect of sedimentation and diagenesis on the quality of lacustral gravity flow tight sandstone reservoirs--A case study of the Chang-7 Member in Heshui area,Ordos Basin

作　　者：霍宏亮 刘成林 李闻达[1,2] 臧起彪 李国雄 卢振东 苏加佳 杨易卓 HUO Hongliang;LIU Chenglin;LI Wenda;ZANG Qibiao;LI Guoxiong;LU Zhendong;SU Jiajia;YANG Yizhuo(National Key Laboratory of Petroleum Resources and Engineering,Beijing,102249;College of Earth Sciences,China University of Petroleum(Beijing),Beijing,102249)

机构地区：[1]油气资源与工程全国重点实验室,北京102249 [2]中国石油大学(北京)地球科学学院,北京102249

出　　处：《地质论评》2024年第6期2411-2427,共17页Geological Review

基　　金：国家重点研发计划项目(编号:2021YFA071900)的成果。

摘　　要：为揭示深水重力流沉积致密砂岩储层发育特征及分布规律,笔者等以鄂尔多斯盆地合水地区三叠系延长组7段(简称长7段)为例,通过岩芯描述、铸体薄片以及扫描电镜观察,结合物性数据以及分析化验资料对研究区长7段沉积、储层岩石学、孔隙类型以及成岩作用特征进行了分析,在沉积和成岩作用特征研究基础上探讨了优质储层的形成机理,据此建立了湖相深水重力流致密砂岩储层质量的演化模式。结果表明:合水地区长7段储层岩性以长石岩屑砂岩为主,孔隙类型主要为溶蚀孔和残余粒间孔,属于特低孔—超低渗储层,主要成岩作用为压实、胶结和溶蚀作用。重力流致密砂岩储层质量受沉积相和成岩作用共同影响,限制性水道中沉积的砂体由于具有强的抗压实能力、少的伊利石和碳酸盐矿物含量以及较多长石、岩屑溶蚀孔隙,储层质量最好。不同沉积环境中的砂岩在颗粒粒度、分选、沉积厚度方面存在差异,通过影响成岩作用类型与强度综合控制储层质量。研究成果可为相同类型储层的预测和评价提供参考。Objectives:This paper aims to study the characteristics and distribution of tight sandstone reservoirs deposited by gravity flow in deep water.Specifically,the study focuses on the 7th Member,Yanchang Formation,Triassic(the Chang-7 Member),in Heshui area,Ordos Basin.Methods:The analysis is conducted through the core description,cast thin slice,and scanning electron microscope observation.By combining physical property data and analytical laboratory data,the study analyzes the petrology,pore types,and diagenetic characteristics of the Chang-7 Member reservoir in the study area.Additionally,the formation mechanism of a high-quality reservoir is discussed based on sedimentary and diagenetic characteristics.Results:The reservoirs of the Chang-7 Member in Heshui area mainly comprise feldspathic lithic sandstone.The pore types are mainly solution and residual intergranular pores,which belong to the ultra-low porosity and ultralow permeability reservoirs.The main diagenetic processes are compaction,cementation,and dissolution.The quality of gravity flow tight sandstone reservoirs is controlled by sedimentary facies,compaction resistance,illite mineral content,and feldspar and other minerals dissolution.Reservoirs deposited in restricted channels generally have the best reservoir quality under relatively weak compaction,cementation,and strong dissolution.Sandstones in different sedimentary environments have differences in particle size,sorting,and sedimentary thickness,which can control reservoir quality by influencing diagenetic type and intensity.Conclusions:There are differences in grain size,sorting and thickness of reservoirs formed in different sedimentary environments,which lead to differential diagenesis and affect reservoir quality.Based on this,a quality evolution model of tight sandstone reservoirs under gravity flow sedimentary background is established.The research results can provide a reference for predicting and evaluating the same type of reservoir.

关 键 词：重力流 致密砂岩 沉积相 成岩作用 储层质量 长7段 鄂尔多斯盆地 

分 类 号：P618.13[天文地球—矿床学]