低温氩气吸附实验在页岩储层微观孔隙结构表征中的应用

Microscopic pore structure characteristics of shale reservoir based on low-temperature argon adsorption experiments

朱汉卿 贾爱林 位云生 贾成业 金亦秋 袁贺

ZHU Hanqing JIA Ailin WEI Yunsheng JIA Chengye JIN Yiqiu YUAN He

中国石油勘探开发研究院, 北京 100083

Research Institute of Petroleum Exploration & Development, CNPC, Beijing 100083, China

针对页岩储层微观非均质性强、孔径分布广泛的特点，使用氩气作为吸附质，通过87 K下的低温氩气吸附实验，研究蜀南地区五峰-龙马溪组富有机质页岩样品的微观孔隙结构特征，并探讨了有机碳含量对页岩微观孔隙结构的影响。结果表明：页岩孔隙呈狭缝型，富有机质页岩样品平均比表面积31.65 m2/g，平均孔体积0.062 2 cm3/g，小于50 nm的微孔和介孔贡献了页岩孔隙中90%以上的比表面积，2~100 nm的介孔和宏孔贡献了页岩孔隙中90%以上的孔体积。有机质含量是影响富有机质页岩微观孔隙发育的主要因素，随着页岩中有机碳含量的增高，页岩比表面积、孔体积增大，微孔占比增多，孔隙表面分形维数增大，孔隙结构非均质性增强，页岩的吸附能力增强。

Shale reservoirs have a strong microscopic heterogeneity and a wide pore size distribution. In this study, argon was used as the adsorbent, and argon isotherm adsorption experiments at 87 K were used to investigate the microscopic pore structure characteristics of six organic-rich shale samples taken from the Upper Ordovician Wufeng-Lower Silurian Longmaxi formations in southern Sichuan Basin. The effect of total organic carbon content on the microscopic pore structure of shale samples was also discussed. The results showed that the pore shape of organic-rich shale samples is slit-like, with an average specific surface area of 31.65 m2/g and an average pore volume of 0.062 2 cm3/g. Over 90% of the specific surface area of the shale samples was provided by micro pores and meso pores, which were less than 50 nm in size, and the 2-100 nm meso pores and macro pores comprising over 90% of the pore volume. TOC content is the main factor affecting the development of organic-rich shale microscopic pores. With the increase of organic carbon content in shale, the specific surface area and pore volume of shale increase, the micro pore ratio increases, and the fractal dimension of pore surface increases, which means that the heterogeneity of pore structure is enhanced. All these factors will enhance the methane adsorption capacity of shale.

国家科技重大专项“页岩气生产规律表征与开发技术政策优化”（2017ZX05037002）资助。

https://doi.org/10.11781/sysydz201804559