鄂尔多斯盆地南部长7段富有机质页岩微观结构特征  

Microstructural characterization of organic-rich shale in Ordos Yanchang Formation

作　　者：张梦雅 李严严 左通 贺昱杰 ZHANG Mengya;LI Yanyan;ZUO Tong;HE Yujie(Faculty of Architecture,Civil and Transportation Engineering,Beijing University of Technology,Beijing 100124,China)

机构地区：[1]北京工业大学,北京100124

出　　处：《世界石油工业》2024年第6期38-45,共8页World Petroleum Industry

基　　金：国家自然科学基金面上项目“鄂尔多斯盆地陆相页岩储层复杂缝网成生演化机制与可压裂性评价研究”(42077258)。

摘　　要：准确评价页岩微观孔隙结构特征对页岩油开发具有重要意义。综合总有机碳含量(TOC)检测、X射线衍射全岩分析、SEM扫描电镜、FIB-SEM技术,对陕西省宜君县2个表面泛有油光的鄂尔多斯盆地延长组长7页岩样品进行岩石物性测试及微观结构特征观测实验。从多角度研究延长组长7段富有机质页岩的微观矿物学、孔隙结构及物性特征,剖析孔喉结构。结果表明:①两块页岩样品TOC含量分别为21.33%、19.33%,具备高TOC特征,有机质丰度很好;②矿物成分复杂,样品主要由黏土矿物、黄铁矿、石英组成,伴有钾长石、斜长石、菱铁矿等赋存;③页岩十分致密,但孔隙类型较为丰富,发育有粒间孔隙、粒内孔隙、有机质孔隙和微裂隙四类微观孔隙,样品1孔隙度为0.39%,样品2孔隙度为0.88%,孔隙发育较差,矿物含量分别为3.95%和8.03%;④页岩样品中的微孔隙尺寸大多为微纳米级,且90%以上都为中孔隙,占据孔隙体积主要部分,样品配位数主要为0和1,孤立孔隙占孔隙的绝大多数,孔隙连通性较差。观测结果对油页岩岩石物理模拟并准确了解其内在特性及勘探目标选址具有重要意义。Accurate evaluation of shale microporous structure characteristics is crucial for the development of shale oil.In this study,TOC detection,X-ray diffraction whole-rock analysis,SEM scanning electron microscopy,and FIB-SEM technology were synthesized to conduct rock microphysical property experiments and microstructure observation experiments on two samples of Chang 7 shale from the Yanchang Formation of the Ordos Basin in Yijun County,Shanxi Province,which are characterized by a shiny oil surface.The micro-mineralogical characteristics,pore structure characteristics,physical properties,and dissection of the pore throat structure of the organic-rich shale in the Long 7 section of the Yanchang Formation have been investigated from multiple perspectives.The results show that:①The TOC contents of the two shale samples are 21.33%and 19.33%,respectively,exhibiting high TOC characteristics and indicating excellent organic matter abundance.②The mineral composition is complex,and samples is mainly composed of clay minerals,pyrite and quartz,accompanied by the occurrence of potassium feldspar,plagioclase feldspar,rhodochrosite and other minerals.③The shale is very dense,but rich in pore types.There are four types of microscopic pores:intergranular pores,intragranular pores,organic matter pores and micro-fissures.The porosity of sample 1 and sample 2 are 0.39%,and 0.88%,the pore space is poorly developed,and the percentage of minerals is 3.95%and 8.03%,respectively.④The size of the micropores in the shale samples is mostly at the microscale and nanoscale,and more than 90%of them are mesoporous and account for most of the pore volume,and the coordination numbers of the samples are mainly 0 and 1.Isolated pores make up the majority of the pores,and pore connectivity is poor.The observation results are critical for reliable petrophysical modeling in oil shales and accurate understanding of their intrinsic properties,as well as for shale exploration target siting.

关 键 词：页岩 微观结构 孔隙类型 孔隙连通性 延长组 鄂尔多斯盆地 

分 类 号：TE122[石油与天然气工程—油气勘探]