液态CO_(2)脉动致裂低渗煤细观结构演化特征分析  

Analysis of the microstructural evolution characteristics of low-permeability coal induced by liquid CO_(2)pulsation fracturing

作　　者：高建良[1,3] 李星 刘佳佳[1,2,3] 朱有彬 GAO Jianliang;LI Xing;LIU Jiajia;ZHU Youbin(School of Safety Science and Engineering,Henan Polytechnic University,Jiaozuo 454003,Henan,China;State Key Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mines,Anhui University of Science and Technology,Huainan 232001,Anhui,China;Henan Collaborative Innovation Center of Coal Work Safety and Clean-Efficiency Utilization,Henan Polytechnic University,Jiaozuo 454003,Henan,China;Beijing Tiandi Huatai Mining Management Co.,Ltd.,Beijing 100013,China)

机构地区：[1]河南理工大学安全科学与工程学院,河南焦作454003 [2]安徽理工大学深部煤矿采动响应与灾害防控国家重点实验室,安徽淮南232001 [3]河南理工大学煤炭安全生产与清洁高效利用省部共建协同创新中心,河南焦作454003 [4]北京天地华泰矿业管理股份有限公司,北京100013

出　　处：《安全与环境学报》2025年第3期955-967,共13页Journal of Safety and Environment

摘　　要：在节能减排的背景下,液态CO_(2)致裂技术不仅能对煤层进行增透,还能对CO_(2)进行地质封存,因此该技术在强化煤层开采领域逐渐被重视。针对低渗煤孔隙之间连通性差且孔隙度低的问题,利用自主搭建的试验系统对低渗煤开展液态CO_(2)脉动致裂试验,基于压汞法、核磁共振法联合表征煤岩的孔隙结构,分析煤岩中不同孔径范围的孔隙比表面积、孔径分布、分形维数和孔隙度等参数的变化,揭示液态CO_(2)脉动作用下低渗煤中细观结构的演化特征。结果表明:液态CO_(2)脉动致裂技术可改变煤岩的孔隙结构和增大煤岩的渗透率;最大累计进汞量和滞后环的相对大小分别增大47.0%和51.8%;微孔和小孔的孔径占比大幅度减小,中孔和大孔的连通性得到显著增强,煤样中出现新生裂隙;渗流孔的分形维数降低,煤样的孔隙分布变得更加规则、孔隙表面变得更加平滑;吸附孔的占比降低超过25%,有效孔隙度增大超过4倍,处理后煤样的渗透率增大超过30倍。In the context of energy conservation and emission reduction,liquid CO_(2)fracturing technology not only enhances the penetration of coal seams but also facilitates geological CO_(2)sequestration.As a result,this technology is increasingly being highlighted in the field of enhanced coal seam mining.To address the issues of poor connectivity and low porosity in low-permeability coal,we conducted liquid CO_(2)pulsation fracturing tests using a self-constructed experimental system.We characterized the pore structure of the coal rock through a combination of piezomercury testing and nuclear magnetic resonance analysis.This approach allowed us to examine changes in specific surface area,pore size distribution,fractal dimensions,and porosity across various pore size ranges in the coal rock.Our findings reveal the evolutionary characteristics of the fine structure of low-permeability coal under the influence of liquid CO_(2)pulsation.The results indicate that the maximum cumulative mercury intake is approximately 1.5 times greater than the previously recorded maximum cumulative mercury intake.The results showed that the maximum cumulative mercury intake and the relative size of the hysteresis loop increased by 47.0%and 51.8%,respectively.Additionally,the proportion of micropores and small pores decreased significantly,while the connectivity of mesopores and macropores was notably enhanced.New cleavages also emerged in the coal samples.The fractal dimension of the seepage pores decreased,resulting in a more regular pore distribution and smoother pore surfaces in the coal samples.Additionally,the percentage of adsorption pores fell by over 25%,while effective porosity increased by more than four times.The permeability of the treated coal samples also rose by more than 30 times.The research results demonstrated that the proposed liquid CO_(2)pulsation fracturing technology can alter the pore structure and enhance the permeability of coal rock.This lays a theoretical foundation for further investigations into the seepage ch

关 键 词：安全工程 液态CO_(2) 脉动致裂 孔径分布 孔隙度 渗透率 

分 类 号：X936[环境科学与工程—安全科学]