川南地区深层页岩孔隙水对纳米孔隙结构的影响及其地质意义  

Influences of pore water on shale nanopore structures and their geological significance for deep shales in the southern Sichuan Basin

作　　者：高海涛 程鹏[1] 吴伟 罗超 李腾飞[1] 田辉[1] GAO Haitao;CHENG Peng;WU Wei;LUO Chao;LI Tengfei;TIAN Hui(State Key Laboratory of Deep Earth Processes and Resources,Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,Guangdong,China;University of Chinese Academy of Sciences,Beijing 100049,China;Shale Gas Research Institute,Southwest Oil and Gas Field Company,PetroChina,Chengdu 610051,Sichuan,China)

机构地区：[1]中国科学院广州地球化学研究所,深地过程与战略矿产资源全国重点实验室,广东广州510640 [2]中国科学院大学,北京100049 [3]中国石油西南油气田分公司页岩气研究院,四川成都610051

出　　处：《地球化学》2025年第2期234-247,共14页Geochimica

基　　金：国家杰出青年科学基金项目(41925014);广东省自然科学基金项目(2021A1515011381);中国石油西南油气田项目(XNS-YYYJS2021-49)联合资助。

摘　　要：川南地区泸州区块五峰组–龙马溪组深层页岩是我国页岩气勘探的重要目标,但对该套页岩的含水性特征还缺乏深入认识。本研究对泸州区块钻井现场采集的一套新鲜页岩样品开展地球化学、含水性以及实取(含水)和干燥状态下的孔隙结构分析,系统研究该套深层页岩的含水性特征及其对纳米孔隙结构的影响。结果表明:该套页岩的孔隙含水量较低,介于5.53~9.33 mg/g之间,平均为7.44 mg/g;页岩孔隙含水量与黏土矿物含量呈显著的正相关关系,表明孔隙水主要储集在页岩无机孔中;孔隙水在不同孔径纳米孔中的分布不同,主要赋存在孔径<10 nm的孔隙之中,并且可能完全堵塞孔径<0.5 nm的微孔。泸州区块五峰组–龙马溪组深层页岩中孔隙水对不同孔径孔隙的影响程度存在显著差别。相对于干燥状态,实取状态下页岩有效孔比表面积平均占比77.90%,其中微孔和非微孔提供的有效比表面积基本相似,两者占比分别为37.13%和40.77%;有效孔体积占比74.74%,非微孔的贡献显著大于微孔,两者占比分别为66.20%和8.54%。因此,地质条件下页岩中的吸附气主要富集在微孔和非微孔之中,而游离气可能主要储集在非微孔中。The deep Wufeng-Longmaxi shales of the Luzhou block in southern Sichuan are important targets for shale gas exploration in China.However,the water-bearing characteristics of these shales are poorly understood.Fresh shale samples collected from drilling sites in this area were analyzed for geochemical characteristics,water content,and pore structure under as-received and dried conditions,and the water content of the deep Wufeng-Longmaxi shales and their effects on nanopore structures were systematically studied.The water content of the deep Wufeng-Longmaxi shales was low,ranging from 5.53 to 9.33 mg/g with an average of 7.44 mg/g.The water content of the shale samples significantly positively correlated with the clay mineral content,indicating that the pore water was mainly stored in inorganic pores.The distribution of pore water varies with nanopore width,mainly occurring in pores with widths less than 10 nm and completely blocking pores with widths less than 0.5 nm.There was a significant difference in the degree of effect of pore water on different pore widths in the deep Wufeng-Longmaxi shales in the Luzhou block.Compared with the pore distribution characteristics of shale samples under dried conditions,the average percentage of effective pore surface area of shale samples under as-received conditions was 77.90%,with micropores and nonmicropores providing similar effective surface areas,accounting for 37.13% and 40.77%,respectively.The average percentage of effective pore volume of the shale samples was 74.74%,with nonmicropores contributing significantly more than micropores,accounting for 66.20% and 8.54%,respectively.Therefore,under geological conditions,adsorbed gas may have similar distribution patterns in micropores and nonmicropores,whereas free gas may be mainly stored in nonmicropores.

关 键 词：孔隙水 深层页岩 孔隙结构 含水性模型 五峰组–龙马溪组 

分 类 号：P618.13[天文地球—矿床学]