鄂西下寒武统牛蹄塘组页岩孔隙结构特征及影响因素

Pore structure characteristics and controls of Lower Cambrian Niutitang Formation, western Hubei Province

何庆 何生 董田 翟刚毅 王亿 万阔

HE Qing HE Sheng DONG Tian ZHAI Gangyi WANG Yi WAN Kuo

1. 中国地质大学(武汉) 构造与油气资源教育部重点实验室, 武汉 430074; 2. 中国地质调查局 油气资源调查中心, 北京 100029; 3. 湖北省地质调查院, 武汉 430034

1. Key Laboratory of Tectonics and Petroleum Resources of Ministry of Education, China University of Geoscience(Wuhan), Wuhan, Hubei 430074, China; 2. Oil and Gas Survey Center, China Geological Survey, Beijing 100029, China; 3. Hubei Geological Survey, Wuhan, Hubei 430034, China

利用低温CO2和N2吸附测试以及场发射-扫描电镜观察、有机碳（TOC）含量测定、X衍射矿物成分分析，对鄂西地区下寒武统牛蹄塘组页岩储层的孔隙结构特征及不同岩相页岩的孔隙发育影响因素进行了研究和探讨。鄂西地区牛蹄塘组页岩的有机碳含量较高，孔隙类型以有机孔和粒内孔为主，且孔隙形态较为复杂；页岩的矿物组分主要以石英和黏土矿物为主。CO2和N2吸附实验显示，页岩孔径分布呈多峰型，介孔多数分布在2~25 nm；页岩的孔隙体积和比表面积主要由微孔和介孔提供。页岩按岩相可分为硅质页岩、混合质页岩和泥质页岩。不同岩相页岩的孔隙发育受TOC和矿物组分的控制机制不同，硅质页岩的孔隙结构主要受TOC和生物硅质含量的影响；混合质页岩的孔隙结构主要受TOC和黏土矿物含量的影响。

The pore structure features of shale in the Lower Cambrian Niutitang Formation in the western Hubei Province were examined using low-temperature CO2 and N2 adsorption tests, Field Emission-Scanning Electron Microscopy (FE-SEM) observations, TOC content measurements, and X-ray diffraction analyses. The TOC content is high in the Niutitang Formation, and the dominant pore types are organic pores and intra-particle pores, displaying complex pore morphology. XRD analysis suggests that the mineral components are dominated by quartz and clays. The CO2 and N2 adsorption experiments show that the pore size distribution displays multi-peaks, and the size of mesopores was mostly within the range of 2-25 nm. The pore volumes and specific surface areas of Niutitang shale are mainly provided by micropores and mesopores. Three shale lithofacies can be identified including siliceous shale, mixed shale and muddy shale. The role of TOC content and minerals on pore development is different in different lithofacies of Niutitang Formation. The porosity development of siliceous shale is mainly affected by the contents of TOC and biogenic silica. The porosity development of mixed shale is mainly affected by the contents of TOC and clay minerals.

国家"十三五"科技重大专项（2016ZX05034-002-003）、国家基础地质调查项目（12120114046901，DD20160185）和中国地质大学（武汉）构造与油气资源教育部重点实验室开放课题基金（TPR-2018-15）联合资助。

https://doi.org/10.11781/sysydz201904530