鄂尔多斯盆地南梁-华池地区长8储层微观孔喉结构差异及成藏意义  

Differences in Microscopic Pore-Throat Structure of Reservoirs and Their Significance for Hydrocarbon Accumulation of Chang 8 Reservoir in the Nanliang-Huachi Area,Ordos Basin

作　　者：张晓辉[1,2] 辛红刚 曹润荣[1,2] 李成[1,2] 马继业[1,2] ZHANG Xiaohui;XIN Honggang;CAO Runrong;LI Cheng;MA Jiye(Exploration and Development Research Institute of PetroChina Changqing Oilfield Company,Xi an,Shaanxi 710018;NationalEngineering Laboratory for Exploration and Development of Low Permeability Oil and Gas Fields,Xi an,Shaanxi 710018)

机构地区：[1]中国石油长庆油田公司勘探开发研究院,陕西西安710018 [2]低渗透油气田勘探开发国家工程实验室,陕西西安710018

出　　处：《地质与勘探》2023年第2期418-432,共15页Geology and Exploration

基　　金：国家科技重大专项课题“鄂尔多斯盆地致密油资源潜力、甜点预测与关键技术应用”(编号:2016ZX05046005);中国石油天然气股份有限公司重大科技专项“鄂尔多斯盆地石油富集规律及勘探目标评价”(编号:2016E-0501);陕西省教育厅科研计划项目“页岩纹层结构差异对页岩油赋存的控制机理”(编号:21JK0839)联合资助。

摘　　要：南梁-华池地区位于鄂尔多斯盆地的湖盆中心,长8层紧邻上部优质烃源岩,是鄂尔多斯盆地勘探开发的重点层系之一。为探究该区不同物性储层微观孔喉结构特征及差异,通过铸体薄片、扫描电镜、高压压汞、恒速压汞等方法,系统研究了南梁-华池地区长81储层微观孔隙结构,对比分析了研究区不同物性样品微观孔喉结构差异及其成因。研究结果表明,南梁-华池地区长8_(1)储层微观孔隙结构复杂多样,微观非均质性较强;随着渗透率的增大,孔喉变异系数、分选系数越大,微观均质系数越小,储层微观非均质性越强;渗透率大于1 mD的储层,大孔喉数量相对较多,连通孔喉半径比、迂曲度较小,孔喉结构多呈“通道型”型,渗透率贡献率主要依靠少数半径大于6μm的连通喉道,而渗透率小于1 mD的储层,连通孔喉半径比较大,孔喉结构多呈“束口袋”型,渗透率贡献率主要由其喉道半径峰值区间的小喉道决定。不同储层物性的微观孔喉差异主要由沉积、成岩差异而形成的。研究区水下分流河道、河口坝主砂带沉积粒度相对较粗,孔隙衬里状绿泥石薄膜发育,薄膜厚度可达10~25μm,可增加岩石颗粒的抗压强度和抑制后期碳酸盐、硅质胶结,有效保存了原生粒间孔;但由于绿泥石薄膜易吸附有机质,致使储层润湿性转向亲油,复杂的孔喉结构与润湿性特征,对该区油气运移、成藏有着重要的影响。The Nanliang-Huachi area is located in the center of the lake basin in the Ordos Basin.The Chang 8 reservoir is adjacent to the upper high-quality hydrocarbon source rock that makes it one of the key layers for exploration and development in the Ordos basin.In order to explore the microscopic pore throat structure characteristics and differences of different physical property reservoirs in this area,the micro pore structure of the Chang 8_(1) reservoir in Nanliang-Huachi area was systematically studied using casting thin section,scanning electron microscope,high pressure mercury injection,and constant velocity mercury injection.The study compared and analyzed the differences in micro pore throat structure of different physical property samples in the study area and their causes.The results showed that the micro pore structure of the Chang 81 reservoir in Nanliang-Huachi area is complex and diverse,with strong micro heterogeneity.With increasing permeability,the variation coefficient and sorting coefficient of pore throat become larger,the micro homogeneity coefficient becomes smaller,and the the micro heterogeneity of the reservoir becomes stronger.For reservoirs with permeability greater than 1 mD,the number of large pore throats is relatively high,the radius ratio of connected pore throats and tortuosity is small,and the pore throat structure is mostly“channel type”.The permeability contribution rate mainly depends on a few connected throats with a radius of more than 6μm.For reservoirs with permeability less than 1 mD,the radius ratio of connected pore throat and tortuosity is relatively large,and the structure of pore throat is mostly“bundle pocket”.The permeability contribution rate is mainly determined by the small throats between the peak areas of throat radius.The difference in micro pore throat of different reservoir physical properties is mainly formed by the difference in sedimentation and diagenesis.In the study area,the sedimentary grain size of the underwater distributary channel and the ma

关 键 词：微观孔隙结构 恒速压汞 微米CT 微观非均质性 长8储层 南梁-华池地区 鄂尔多斯盆地 

分 类 号：TE122[石油与天然气工程—油气勘探]