柴达木盆地西部南翼山地区新近系油砂山组Ⅲ-Ⅴ油组藻灰岩储层特征及控制因素  

Characteristics and Controlling Factors of Algal Limestone Reservoir in Neogene Youshashan Formation III-V Oil Group,Nanyishan Oilfield of Western Qaidam Basin

作　　者：郭德光 李琦[1,2] GUO De-guang;LI Qi(Ocean Sciences College,China University of Geosciences(Beijing),Beijing 100083,China;Hainan Institute of China University of Geosciences(Beijing),Sanya 572025,China)

机构地区：[1]中国地质大学(北京)海洋学院,北京100083 [2]中国地质大学(北京)海南研究院,三亚572025

出　　处：《科学技术与工程》2024年第36期15413-15426,共14页Science Technology and Engineering

基　　金：国家自然科学基金(41576066)。

摘　　要：柴达木盆地西部南翼山地区新近系湖相碳酸盐岩发育广泛,其中藻灰岩储层是最优储层。为进一步探索其储层特征及控制因素,通过厘米级别岩心描述、重点井段取样综合分析和测录井资料,对柴达木盆地西部地区南翼山油田新近系油砂山组III-V油组藻灰岩储层进行研究。结果表明:油砂山组III-V油组储层有明显的混积特征,以碳酸盐岩为主,平均质量分数40.2%,黏土矿物和陆源碎屑平均质量分数分别为27.8%和23.2%,储层岩性主要以藻灰岩和灰云岩为主,平均体积分数分别为33.6%和42.9%。藻灰岩分为藻团块灰岩、藻叠层灰岩、藻凝块灰岩3种类型,结构组分主要是藻球粒和内碎屑,其次是藻丝结构、团块、藻屑和黏连组构;灰云岩分为砂质泥晶云岩、颗粒泥晶灰岩和泥晶灰岩3种岩性,主要由颗粒、泥晶基质和胶结物组成。研究区储层孔隙以溶蚀孔和晶间孔为主,微裂缝发育。藻灰岩以溶蚀孔为主,非均质性强,饱和度中值半径0.085μm,细喉道,样品孔隙度23.17%,渗透率54.3 mD,排驱压力2.97 MPa,表现高孔中渗特征。灰云岩孔喉均匀,饱和度中值半径0.039μm,微型喉道,样品孔隙度17.24%,渗透率15.13 mD,排驱压力10.34 MPa,表现中孔低渗特征。藻灰岩孔隙结构优于灰云岩,储层质量更高。研究区储层主要受控于岩性、矿物种类、碳酸盐矿物含量和成岩作用,泥质含量增加会降低储层质量,碳酸盐岩含量与储层质量呈正相关,溶蚀作用与白云石化作用对储层是建设性成岩作用,改善了储层的空间结构,胶结作用会破坏储层结构,降低储层物性。The Neogene lacustrine carbonate rocks are widely developed in the Nanyishan Oilfield in the western part of the Qaidam Basin,of which the algal limestone reservoir is the optimal reservoir.In order to further explore its reservoir characteristics and controlling factors,the algal limestone reservoir of the neogene Youshashan Formation III-V oil group in the Nanyishan Oilfield was studied through centimeter-level core descriptions,comprehensive analysis of samples taken from key wells,logging and recording well data,located in the western region of the Qaidam Basin.It is found that the reservoirs of Youshashan Formation III-V have obvious miscible characteristics,dominated by carbonate rocks with an average mass fraction of 40.2%,and the average mass fractions of clay minerals and terrigenous clasts are 27.8%and 23.2%,respectively.The lithology of the reservoirs is mainly dominated by algal limestone and grey dolomites,with an average volume fraction of 33.6%and 42.9%,respectively.Algal limestone is divided into three types:algal mass limestone,algal stromatolite limestone and algal clot limestone.The main structural components are algal spherules and endoclasts,followed by algal filament structures,clumps,algal debris and cohesive fabric.Grey dolomites are divided into sandy limestone,granular micrite and micrite,with lithologies mainly consisting of particles,micrite matrix,and cement.Reservoir pores in the study area are dominated by dissolved pores and intercrystalline pores,and microfractures are developed.The algal limestone is dominated by dissolved pores,showing strong non-homogeneity with a median saturation radius of 0.085μm,small throat size,sample porosity of 23.17%,permeability of 54.3 mD,and displacement pressure of 2.97 MPa,which exhibits high pore and medium seepage characteristics.The grey dolomite has uniform pore throat,with median saturation radius of 0.039μm,micro-throat channel,sample porosity of 17.24%,permeability of 15.13 mD,drainage pressure of 10.34 MPa,showing the characteristics of

关 键 词：藻灰岩 储层特征 控制因素 油砂山组 南翼山油田 

分 类 号：TE122[石油与天然气工程—油气勘探]