陆相页岩层段储集特征及其油气地质意义——以四川盆地中部大安寨段为例  

Reservoir characteristics and its petroleum significance of Jurassic Da’anzhai shale interval in central Sichuan Basin,SW China

作　　者：张少敏 杨跃明[3] 洪海涛 曾溅辉[4] 张芮 李育聪 何绪全 ZHANG Shaomin;YANG Yueming;HONG Haitao;ZENG Jianhui;ZHANG Rui;LI Yucong;HE Xuquan(Exploration and Development Research Institute,Southwest Oil&Gas Field Company,PetroChina,Chengdu,Sichuan 610041,China;Shale Gas Evaluation and Exploitation Key Laboratory of Sichuan Province,Chengdu,Sichuan 610213,China;PetroChina Southwest Oil&,Gasfield Company,Chengdu,Sichuan 610051,China;China University of Petroleum,Beijing 102249,China)

机构地区：[1]中国石油西南油气田公司勘探开发研究院,四川成都610041 [2]页岩气评价与开采四川省重点实验室,四川成都610213 [3]中国石油西南油气田公司,四川成都610051 [4]中国石油大学(北京)地球科学学院,北京102249

出　　处：《中国矿业大学学报》2022年第4期718-730,共13页Journal of China University of Mining & Technology

基　　金：中国石油西南油气田公司科技项目(20200301-03);中国石油勘探与生产分公司科技项目(2021DJ1801-08)。

摘　　要：为精细评价陆相页岩储层特征,有效指导页岩油勘探开发,以四川盆地中部侏罗系自流井组大安寨段页岩层系为例,综合应用岩心精描、薄片鉴定、扫描电镜观察、核磁共振、氮气吸附和测井解释等定性和定量的分析方法,对页岩层系岩相和储层微观特征进行研究.提出了页岩层系岩相划分方案,认为大安寨段页岩层系具有以裂缝和溶蚀宏孔为主的微米级储集空间和纳米级孔、缝构成的双重介质,明确了纹层状含介壳页岩及薄层状介壳灰质页岩/泥质介壳灰岩为有利储集岩类,岩相类型和成岩作用是造成储集性能差异的主要因素,富有机质页岩与介壳灰质夹层形成源储一体的有利配置.研究结果表明:大安寨段页岩层系主要包括纹层状长英质页岩、纹层状含介壳页岩、层状—块状黏土质粉砂岩、薄层状介壳灰质页岩、薄层状泥质介壳灰岩和块状介壳灰岩6种岩相类型;块状介壳灰岩孔隙度平均为1.01%,其他(含介壳)页岩孔隙度平均为1.12%~4.85%,页岩层系储集空间以纳米级孔隙为主,形态以狭缝状为主,孔径主要分布为10~5×10~3 nm,介孔和宏孔发育.大安寨段湖相页岩层系含油气性较好,有机质发育的纹层状或薄层状(含介壳)页岩受有机酸溶蚀增孔的作用,形成大量次生孔隙,从而形成了源储一体的富有机质页岩与介壳灰质夹层有利配置,夹层中(微)裂缝和溶蚀宏孔为游离烃提供主要的储集空间,页岩基质内广泛发育的纳米孔,孔径小、连通性较差,两者形成的微纳米级孔-缝双重介质,使大安寨段油气稳产成为可能,对于四川盆地的陆相页岩油气勘探开发具有重要的意义.In order to precisely evaluate lacustrine shale reservoir and effectively guide the shale oil exploration and development, the Jurassic Da’anzhai shale interval in central Sichuan Basin were taken as a research object. Based on comprehensive application of core analysis, thin sections inspection, scanning election microscope(SEM) observation, qualitative and quantitative test of nuclear magnatic resonance, nitrogen adsorption and well logging interpretation, the lithofacies and reservoir micro-structures were studied. Division method of shale lithofacies was proposed, and it shows that micron scale reservoir space dominated by fractures and large pores, together with nanoscale pores and fractures, build up the multi-scale dual pore system. Laminated shell-containing shale and thin-layered shell limy shale/muddy shell limestone are identified as the most favorable reservoir types. The differences of reservoir performance are mainly affected by lithofacies type and diagenesis variety, forming the favourable integrated source and reservoir type as organic matter rich shale and shell limy interlayer. The results show that there were six types of lithofacies mainly developed in the Da’anzhai shale interval, which are laminated felsic shale, laminated shell-containing shale, laminated-massive muddy siltstone, thin-layered shell limy shale, thin-layered muddy shell limestone and massive shell limestone. The average porosity of massive shell limestone is about 1.01%, while(shell-containing) shale ranging from 1.12% to 4.85%. Reservoir space of the shale interval is mainly nanoscale pores, exhibiting a slit shape with well connectivity. The width of pore diameter spreads from 10 to 5×10~3 nm, including mesoporous and macroporous development. Da’anzhai shale interval shows good oil and gas possibility, organic matter rich shale and shell limy interlayer are dissolved to develop a number of second pores by organic acid. The micro fractures and dissolved macropores provide the main reservoir space for free hydrocarbon

关 键 词：岩相类型 储集性能 主控因素 页岩层系 大安寨段 川中地区 

分 类 号：TE121[石油与天然气工程—油气勘探]