考虑温度、孔隙压力影响的煤岩渗透性演化机制分析  

Analysis of coal permeability evolution mechanism considering the effect of temperature and pore pressure

作　　者：李波波[1,2,3] 高政 杨康 李建华[1] 任崇鸿 袁梅 汪泓[1,2,3] LI Bobo;GAO Zheng;YANG Kang;LI Jianhua;REN Chonghong;YUAN Mei;WANG Hong(College of Mining,Guizhou University,Guiyang 550025,China;The National Joint Engineering Laboratory for the Utilization of Dominant Mineral Resources in Karst Mountain Area,Guizhou University,Guiyang 550025,China;Guizhou Key Laboratory of Comprehensive Utilization of Non-metallic Mineral Resources,Guiyang 550025,China)

机构地区：[1]贵州大学矿业学院,贵州贵阳550025 [2]贵州大学喀斯特山区优势矿产资源高效利用国家地方联合工程实验室,贵州贵阳550025 [3]贵州省非金属矿产资源综合利用重点实验室,贵州贵阳550025

出　　处：《煤炭学报》2020年第2期626-632,共7页Journal of China Coal Society

基　　金：国家自然科学基金资助项目(51804085);贵州省科技计划资助项目(黔科合LH字[2016]7465号);贵州省科学技术基金资助项目(黔科合J字[2015]2049号)

摘　　要：为探究煤层气抽采过程中温度与孔隙压力对煤岩渗透特性变化的影响,以贵州黔北煤田原煤为研究对象,利用自主研发的出口端正压三轴渗流装置,通过控制进出口气体压力分别设定3个不同压差条件,开展不同温度下改变孔隙压力的渗流试验。在当前典型的S&D模型基础上结合温度引起的吸附变形、热膨胀和滑脱效应的作用,新建考虑温度和恒定外应力条件下的渗透率模型。通过试验与模型对比验证其合理性,并对有无考虑滑脱效应的渗透率计算值进行了定量分析。结果表明:①渗流试验过程中,煤岩渗透率随孔隙压力升高而降低,其渗透率下降量受温度升高影响呈现降低趋势;孔隙压力升高,煤岩渗透率受温度影响的敏感程度逐渐降低。②在试验的各孔隙压力点下,温度升高使得煤岩渗透率降低;在各温度状态下,煤岩渗透率随压差增大呈现降低趋势。③经定量分析后发现修正模型较其他两个模型更加符合试验结果,且修正模型的滑脱因子随温度升高而增大,从理论方面验证了模型的合理性。④考虑滑脱效应的煤岩渗透率曲线比不考虑滑脱效应的渗透率曲线更加符合试验结果。在不同温度条件下,前者的渗透率计算值大于后者的计算值。随孔隙压力升高,滑脱效应引起的渗透率变化量逐渐降低。In order to explore the influence of temperature and pore pressure on the variation of coal permeability during the process of coalbed methane extraction,the original coal samples from the Qianbei coalfield of Guizhou were investigated in this study.The experimental instrument is a positive pressure triaxial seepage device developed independently.Three different differential pressure conditions were set by controlling the inlet and outlet gas pressure.Then the seepage tests were carried out,in which the pore pressure at different temperatures was varied.On the basis of the S&D model,one of the current typical permeability models,combined with the effects of temperature-induced adsorption deformation,thermal expansion and slippage effects,a new permeability model considering temperature and constant external stress was newly established.The rationality was verified by ex-periment and model comparison.Quantitative analysis was also made on the calculated values of permeability considering slippage effect and those without considering slippage effect.The results show that ① during the seepage test,the permeability of coal decreases with the increase of pore pressure,and the decrease is affected by the increase of temperature.With the increase of pore pressure,the sensitivity of coal permeability to temperature decreases gradually.② Under the pressure point of each pore of the test,the temperature increase causes the permeability of coal to decrease;under each temperature state,the permeability of coal decreases with the increase of pressure difference.③ After quantitative analysis,it is found that the modified model is more consistent with the experimental results than the other two models,and the value of slip factor of the modified model increases with the increase of temperature,which proves the rationality of the model theoretically.④ The permeability curve of coal with slippage effect is more consistent with the test results than that without slippage effect.The calculated value of the former is higher

关 键 词：煤岩 渗透率 孔隙压力 温度 压差 

分 类 号：P618.11[天文地球—矿床学]