川西坳陷须家河组四段致密砂岩储层可动流体饱和度影响因素  

INFLUENCING FACTORS OF MOBILE FLUID SATURATIONIN THE TIGHT SANDSTONE RESERVOIR IN THE 4^(TH) MEMBER OF XUJIAHE FORMATION(T_(3)x^(4)),WESTERN SICHUAN BASIN

作　　者：王剑超 余瑜[1,2] 林良彪[1,2] 邓予炜 南凡驰 WANG Jianchao;YU Yu;LIN Liangbiao;DENG Yuwei;NAN Fanchi(State Key Laboratory of Oil and Gas Reservoir Geology and Eaploitation,Chengdu University of Technology,Chengdu,Sichuan 610059,China;Institute of Sedimentary Geology,Chengdu University of Technology,Chengdu,Sichuan 610059,China;Keyuan Engineering Technical Test Center of Sichuan Province,Chengdu,Sichuan 610091,China)

机构地区：[1]油气藏地质及开发工程国家重点实验室成都理工大学,四川成都610059 [2]成都理工大学沉积地质研究院,四川成都610059 [3]四川省科源工程技术测试中心,四川成都610091

出　　处：《矿物岩石》2023年第2期95-107,共13页Mineralogy and Petrology

基　　金：国家自然科学基金(项目批准号:42202128);油气藏地质及开发工程国家重点实验室(成都理工大学)开放基金项目(编号:PLC20210110)。

摘　　要：为研究四川盆地西部须家河组四段致密砂岩储层可动流体赋存特征和影响因素,结合铸体薄片、扫描电镜(SEM)、矿物全岩分析(XRD)等实验方法,分析其储层特征和孔隙微观结构特征;在此基础上利用核磁共振实验(NMR)及高压压汞实验对研究区典型岩心进行测试,详细分析、评价其可动流体赋存特征及其影响因素。结果表明研究区须四段砂岩储层样品核磁孔隙度介于1.72%~6.63%,平均值为4.34%;渗透率介于0~0.0152×10^(-3)μm^(2);可动流体饱和度介于7.92%~32.66%;核磁共振T_(2)图谱可分为单峰型、双峰型及多峰型;按照孔喉大小分类,样品中孔喉50%以上为纳米孔。压汞分析结果显示样品排驱压力高,介于1.18~4.57 MPa,平均为2.45 MPa;最大进汞饱和度高,介于46.91%~97.66%,平均为63.28%;退汞效率介于14.09%~38.97%,平均为29.55%,反映出研究区须四砂岩样品具有孔隙分选差,非均质性强,孔隙连通性差的特点。分析认为样品的可动流体赋存特征差异主要受到来自储层物性、孔隙微观结构及矿物组分的影响。储层物性中,渗透率对样品可动流体赋存具有明显的正相关影响,而孔隙度对可动流体饱和度的影响较小。孔喉的结构及连通性对可动流体的赋存具有一定的控制作用,表现为样品的中值半径越大,越有利于可动流体赋存。研究区样品长石含量与可动流体饱和度之间存在明显正相关;黏土矿物通过占据、堵塞孔隙,不利于可动流体饱和度,但样品中伊利石含量与可动流体显示出明显的正相关性,推测认为伊利石的含量高低从侧面证明了长石的溶解程度,含量越高指示溶蚀孔隙越发育,因而可动流体越高。The characteristics of tight sandstone reservoir and pore microstructure of the 4~(th)member of Xujiahe Formation(T_(3)x^(4))in western Sichuan Basin were analyzed by using by methods of cast thin section,scanning electron microscopy(SEM)and mineral whole rock analysis(XRD).Typical cores in the study area were selected for test by nuclear magnetic resonance(NMR)and high pressure mercury injection for the purpose of analyzing and evaluating the characteristics of movable fluid occurrence and its influencing factors.The results show that the nuclear magnetic porosity of the T_(3)x^(4) in the study area ranges from 1.72% to 6.63%,with an average value of 4.34%,permeability ranges from 0 to 0.0152×10^(-3)μm^2.The mobile fluid saturation ranges from 7.92% to 32.66%.The NMR T_(2) map can be divided into unimodal,bimodal and multi-modal patterns.More than 50% of pore throats in the sample are classified as nanopores.Mercury injection analysis results showed that the displacement pressure of the samples was high,ranging from 1.18 to 4.57 MPa,with an average of 2.45 MPa and the maximum mercury intake saturation was high,ranging from 46.91% to 97.66%,with an average of 63.28%.The mercury removal efficiency ranges from 14.09% to 38.97%,with an average of 29.55%,which reflects the characteristics of poor pore sorting,strong heterogeneity and poor pore connectivity of T_(3)x^(4) sandstone samples in the study area.Analysis of reservoir physical properties shows that permeability has an obvious positive correlation with the occurrence of movable fluid,while porosity has little effect on the saturation of movable fluid.The structure and connectivity of pore throat have a certain control effect on the occurrence of movable fluid,indicating that the larger the median radius of the sample,the more favorable the occurrence of movable fluid.There is an obvious positive correlation between feldspar content and mobile fluid saturation.It is recognized that the obvious positive correlation of illite content in the samples with the mo

关 键 词：川西坳陷 须家河组 致密砂岩 可动流体 核磁共振 

分 类 号：TE122.1[石油与天然气工程—油气勘探]