致密砂岩储层可动流体分布及影响因素研究——以吉木萨尔凹陷芦草沟组为例  

Distribution characteristics and influencing factors of movable fluid in tight sandstone reservoirs:a case study of Lucaogou Formation in Jimsar Sag,NW China

作　　者：李闽[1] 王浩[1] 陈猛[1] 

机构地区：[1]油气藏地质及开发工程国家重点实验室.西南石油大学,成都610500

出　　处：《岩性油气藏》2018年第1期140-149,共10页Lithologic Reservoirs

基　　金：国家重点基础研究发展(973计划)项目"致密油多相多尺度流动机理及渗流理论研究"(编号:2015CB250902);石油化工联合基金(A类)项目"致密气多相多尺度流动规律及跨尺度耦合渗流"(编号:U1562217)联合资助

摘　　要：明确可动流体含量、分布及影响因素是有效评价致密储层开发潜能的基础。选取准噶尔盆地芦草沟组21块致密砂岩样品,采用核磁共振T_2谱分析和离心实验相结合的方法,测量岩样在不同含水饱和度下的核磁共振T_2谱,并辅以铸体薄片和扫描电镜技术分析储层可动流体含量差异的影响因素。结果表明:储层岩样核磁共振T_2谱主要呈现为5种形态,复杂的储层微观特征和孔喉结构均是导致核磁共振T_2谱形态多样的主要原因;储层建立束缚水饱和度的最佳离心力是400~450 psi,计算得到可动流体饱和度为29.44%~68.92%,平均值为46.69%,不同岩样可动流体含量和分布均有明显差异,可动流体分布的有效孔喉半径下限约为50 nm,储层主流喉道半径为70~200 nm;可动流体含量和物性参数之间的关系表明,对于物性较差的储层,渗透率是决定可动流体含量的主要因素,但对于物性较好的储层,渗透率对可动流体含量的影响较小;孔隙类型、形状及表面粗糙程度均会影响储层束缚水含量和分布;储层次生孔隙的发育程度及分布、孔喉半径大小及连通性、黏土矿物的充填程度及产状和裂缝的发育情况都会对可动流体含量产生影响。该研究成果可为致密储层开发潜力评价提供依据。Determining the content, distribution and influencing factors of movable fluid is the basis for effective evaluation of the development potential of tight reservoir. 21 samples of tight sandstone reservoirs of Lucaogou Formation in Junggar Basin were selected to measure the NMR T： spectrum at different degrees of water saturationby using NMR T2 spectrum analysis and centrifuge tests, and the influencing factors of the differences in the movable fluid were analyzed by cast thin section and scanning electron microscopy. The results show that the T~ spec- trum of reservoir rocks is mainly manifested by five forms, and the complexity of reservoir micro-characteristics and pore throat structure are the main reasons for the various types of NMR T2 spectrum. The best centrifugal force for tight oil reservoir to make bound water state is 400-450 psi, the saturation of movable fluid is 29.44%- 68.92%, and the average value is 46.69%. The content and distribution of the movable fluid in different rock sam- ples are obviously different, and the minimum of pore throat radius of the movable fluid distribution is about 50 nm, and the mainstream throat radius is 70-200 nm. The relationship between movable fluid content and phys- ical property shows that for the reservoirs with poor physical properties, the permeability is the main controlling factors, but for the reservoirs with better physical properties, the impact of permeability on the movable fluid content is small. The pore type, shape and surface roughness all affect the content and distribution of the bound water. The development and distribution of secondary pores, the size of pore throat and its connectivity, the fill- ing degree and occurrence of clay minerals and the development of cracks, are the influencing factors of mov- able fluid content. These results can provide a basis for evaluating the development potential of tight reservoirs.

关 键 词：核磁共振 可动流体分布 孔喉半径 影响因素 芦草沟组 准噶尔盆地 

分 类 号：TE122.23[石油与天然气工程—油气勘探]