摘要
深部不可采煤层的CO_(2)增强煤层气采收率技术(CO_(2)-ECBM)是实现“双碳”目标的重要途径之一,但其涉及的CO_(2)在煤层中的长期封存安全性问题亟待解决,解决该问题的关键在于研究超临界CO_(2)(ScCO_(2))作用下的不同尺度煤力学性能演化和破坏机理,而颗粒煤力学特性及断裂机制方面相关研究较少。本文选取陕西省郭家河煤矿烟煤为研究对象,开展了不同ScCO_(2)浸润时间下的颗粒煤力学特性研究,基于颗粒单轴压缩试验研究颗粒煤力学参数随浸润时间的变化规律,结合扫描电镜实验(SEM)探讨不同ScCO_(2)浸润时间作用颗粒煤力学性能的时间效应和断裂机制的演化过程。研究结果表明:颗粒煤力学性能随ScCO_(2)浸润时间的不同具有显著差异,基于24 h为时间分界线,将ScCO_(2)对颗粒煤力学特性的影响分为短时物理速劣效应和长时化学缓劣效应,在短时物理速劣效应中,ScCO_(2)的吸附膨胀引起的微裂纹对颗粒煤弹性变形阶段产生快速影响;而在长时化学缓劣效应中,煤分子结构的变化、有机质萃取和矿物溶蚀作用成为主导,这些作用影响颗粒煤力学性能的速度较为缓慢且影响能力较小。ScCO_(2)的膨胀变形、有机质萃取和矿物溶蚀作用使颗粒煤的弹性应变能释放和表面能降低,从而加速了裂纹扩展过程中的能量释放;通过构建颗粒煤断裂机制演化模型,进一步阐释了ScCO_(2)时间效应对颗粒煤断裂机制的影响,短时物理速劣效应颗粒煤的断裂主要受微裂纹密度增加的影响,长时化学缓劣效应对颗粒煤断裂机制的影响以模型内部应力集中点位和孔隙数量增加为主。
Enhanced coalbed methane(ECBM)recovery technology through CO_(2) sequestration in deep unminable coal seams,denoted as CO_(2)-ECBM,is one of the pivotal strategies for achieving the dual-carbon targets.However,the longterm safety of CO_(2) sequestration within coal strata remains a pressing issue that necessitates resolution.The crux of this challenge lies in the investigation of the evolution and failure mechanisms of coal mechanical properties at various scales under the influence of supercritical CO_(2)(ScCO_(2)),with a particular scarcity of research on the mechanical characteristics and fracture mechanisms of particulate coal.This study focuses on anthracite from the Guojiahe coal mine in Shaanxi Province,China,and conducts a study on the mechanical properties of particulate coal under varying durations of ScCO_(2) saturation.By employing uniaxial compression tests on particulate coal and integrating scanning electron microscopy(SEM)experiments,we explore the time effects of ScCO_(2) saturation on the mechanical properties and the evolution of fracture mechanisms over different periods.The findings reveal significant disparities in the mechanical properties of particulate coal contingent upon the duration of ScCO_(2) saturation,with a demarcation at 24 hours.This threshold distinguishes the short-term physical rapid deterioration effects,characterized by rapid impacts on the elastic deformation stage due to micro-cracks induced by ScCO_(2) adsorption expansion,from the long-term chemical slow deterioration effects,dominated by changes in coal molecular structure,organic matter extraction,and mineral dissolution,which exert a slower and less potent influence on coal mechanical properties.The expansion,organic extraction,and mineral dissolution induced by ScCO_(2) lead to the release of elastic strain energy and a reduction in surface energy of particulate coal,thereby accelerating energy release during crack propagation.By constructing a model for the evolution of particulate coal fracture mechanisms,we further elucidate the impact of ScCO_(2) time effects on these mechanisms,with short-term physical rapid deterioration effects primarily influenced by an increase in micro-crack density and long-term chemical slow deterioration effects characterized by an increase in stress concentration points and internal porosity,as assumed by the model.
作者
刘敏轩
王亮
郑思文
吴淞玮
赵月辰
张保勇
刘超
LIU Minxuan;WANG Liang;ZHENG Siwen;WU Songwei;ZHAO Yuechen;ZHANG Baoyong;LIU Chao(State Key Laboratory of Coal Mine Disaster Prevention and Control,China University of Mining and Technology,Xuzhou 221116,China;Key Laboratory of Theory and Technology on Coal and Rock Dynamic Disaster Prevention and Control,National Mine Safety Administration,China University of Mining and Technology,Xuzhou 221116,China;National Engineering Research Center for Coal Gas Control,China University of Mining and Technology,Xuzhou 221116,China;School of Safety Engineering,Heilongjiang University of Science&Technology,Harbin 150022,China;School of Mechanics and Civil Engineering,China University of Mining and Technology,Xuzhou 221116,China)
出处
《煤炭学报》
2025年第9期4405-4415,共11页
Journal of China Coal Society
基金
国家自然科学基金资助项目(52474260)
江苏省研究生科研与实践创新计划资助项目(KYCX24_2907)
中国矿业大学研究生创新计划资助项目(2024WLKXJ132)。
关键词
超临界CO_(2)
时间效应
颗粒煤
力学特性
断裂机制
supercritical CO_(2)
time effect
particle coal
mechanical properties
fracture mechanism
作者简介
刘敏轩(2000-),男,河南平顶山人,博士研究生。E-mail:liuminxuan@cumt.edu.cn;通讯作者:王亮(1982-),男,江苏东海人,教授,博士。E-mail:wangliang@cumt.edu.cn。
