煤孔裂隙多尺度表征及其对渗透率的影响分析——以中国14个大型煤炭基地为例  

Multi-scale characterization of coal pore and fractures and its influence on permeability—taking 14 large coal bases in China as examples

作　　者：王刚[1,2] 陈雪畅 程卫民[1,2] 陈昊 WANG Gang;CHEN Xuechang;CHENG Weimin;CHEN Hao(Mining Disaster Prevention and Control-Ministry of State Key Laboratory Breeding Base,Shandong University of Science and Technology,Qingdao,Shandong 266590,P.R.China;b.College of Safety and Environmental Engineering,Shandong University of Science and Technology,Qingdao,Shandong 266590,P.R.China)

机构地区：[1]山东科技大学矿山灾害预防控制国家重点实验室培育基地,山东青岛266590 [2]山东科技大学安全与环境工程学院,山东青岛266590

出　　处：《重庆大学学报》2024年第4期34-50,共17页Journal of Chongqing University

基　　金：国家自然科学基金资助项目(51934004,51974176);山东省自然科学基金杰出青年基金资助项目(ZR2020JQ22)。

摘　　要：为探究煤体不同尺度孔裂隙特征及其对渗透率的影响,从我国14个大型煤炭基地分别取样,进行氮气吸附、压汞和CT实验,并将CT扫描后的煤样进行渗流实验。结果表明,各煤样中微孔和过渡孔多为封闭孔,连通性差,不利于渗流的进行。r=10 nm和r=100μm的孔裂隙体积占比相对较大,贡献了煤体大部分孔隙率,S2和S3中的大尺度平行板孔隙为渗流提供了充足的空间。通过划分3种实验表征的优势孔径段,提出了综合表征孔隙率和分形维数的方法,得到各煤样的孔隙率范围为1.62%~11.60%,分形维数范围为2.29~2.78。煤样渗透率在0.0002×10^(-15)~0.6525×10^(-15)m^(2)之间,以中低渗为主。r<50 nm、50 nm≤r≤8.5μm和r>8.5μm的孔隙率分量与渗透率的关系分别为y=0.2741x-0.0781、y=0.0674x+0.0237和y=0.0039x^(2.5986),其中r>8.5μm的孔隙率分量与渗透率的相关性最强。相对于氮气吸附和压汞实验,CT实验更适用于分析孔裂隙结构对水渗的影响。In order to explore the characteristics of pores and fractures at different scales and their influence on permeability,nitrogen adsorption,mercury injection and CT experiments were carried out on 14 large coal bases in China.Seepage experiments were then conducted on the coal samples after CT scanning.The results showed that the micropores and transition pores in each coal sample are mostly closed pores with poor connectivity,which is not conducive to coal seepage.The pore and fractures volume with r=10 nm and r=100μm accounts for a large proportion,contributing most to the porosity of coal.Large-scale parallel plate pores in S2 and S3 provide sufficient space for seepage.By dividing dominant pore size segments characterized by three experiments,a method for comprehensively characterizing porosity and fractal dimension is proposed.The porosity range of each coal sample is from 1.62%to 11.60%,and the fractal dimension range is from 2.29 to 2.78.The permeability of coal samples ranges from 0.0002×10-152 m to 0.6525×10-15 m2,mainly in medium and low permeability.The relationship between the porosity components of r<50 nm,50 nm≤r≤8.5μm and r>8.5μm and permeability is 2.598 as follows:y=0.2741x-0.0781,y=0.0674x+0.0237 and y=0.0039x 6,respectively.The correlation between the porosity component of r>8.5μm and permeability is the strongest.Compared with nitrogen adsorption and mercury intrusion experiments,the CT experiment is more suitable for analyzing the influence of pore and fractures on water seepage.

关 键 词：煤 多尺度表征 分形维数 孔隙率 渗透率 

分 类 号：TU443[建筑科学—岩土工程]