不同注源气体置换-驱替煤层甲烷突破时间的差异性分析
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摘要
煤层注气促抽瓦斯是近年来逐步发展起来的强化抽采技术,注气突破时间是该技术的重要参数之一。突破时间是指注源气体从煤层一端注入到另一端检测出该组分所需的时间,它与注源气体的吸附性、渗透性有着密切的关系。为了研究渗透和吸附对注气突破时间的影响规律,利用含瓦斯煤层注气模拟实验装置,进行了煤层注He,N_2和CO_2置换-驱替CH_4的实验室模拟实验。实验结果表明,不考虑煤对气体吸附性的纯渗流条件下,N_2和CO_2纯渗流突破时间极短,仅为总突破时间的5.93%和0.28%,表明气体吸附性能是引起总突破时间差异的主要因素;另外,随着注源气体吸附性增强,其总突破时间大幅度增加,He,N_2和CO_2的总突破时间分别为0.92,14,246 min。实验结果结合理论模型计算分析得出:注源气体吸附性越强,总突破时间越长,注气初期的置换效应越明显,但随着注源气体的吸附不断趋于饱和,其驱替效应逐渐增强。
Coal gas injection is an intensive extraction technology which is gradually developed in recent years,and the breakthrough time of gas injection is one of the important parameters of the technology.The breakthrough time is the required time of injection gas goes from one end of the coal seam to the other end,and it is closely related to the adsorption and the permeability of the source gas.In order to study the laws of permeability and adsorption on the breakthrough time,the laboratory simulation experiment is carried out with injecting He,N_2 and CO_2 in coal seams to replace-displace CH_4.The results show that thebreakthrough time on pure seepage of N_2 and CO_2 is very short,only 5.93% and 0.28% of the total breakthrough time,which indicates that gas adsorption performance is the main factor that causes the difference of breakthrough time.The breakthrough time increases as the gas adsorption performace of injection gas increases,and the breakthrough time of He,N_2 and CO_2 is 0.92 min,14 min and 246 min,respectively.According to the laboratory experiment and theoretical model analysis,it can be concluded that the stronger the adsorption performance of injection gas is,the longer the breakthrough time and the more obvious the replacement effect in the initial stage of gas injection is,but the displacement effect gradually increases as the adsorption of the injection gas tends to be saturated.
Coal gas injection is an intensive extraction technology which is gradually developed in recent years,and the breakthrough time of gas injection is one of the important parameters of the technology.The breakthrough time is the required time of injection gas goes from one end of the coal seam to the other end,and it is closely related to the adsorption and the permeability of the source gas.In order to study the laws of permeability and adsorption on the breakthrough time,the laboratory simulation experiment is carried out with injecting He,N_2 and CO_2 in coal seams to replace-displace CH_4.The results show that thebreakthrough time on pure seepage of N_2 and CO_2 is very short,only 5.93% and 0.28% of the total breakthrough time,which indicates that gas adsorption performance is the main factor that causes the difference of breakthrough time.The breakthrough time increases as the gas adsorption performace of injection gas increases,and the breakthrough time of He,N_2 and CO_2 is 0.92 min,14 min and 246 min,respectively.According to the laboratory experiment and theoretical model analysis,it can be concluded that the stronger the adsorption performance of injection gas is,the longer the breakthrough time and the more obvious the replacement effect in the initial stage of gas injection is,but the displacement effect gradually increases as the adsorption of the injection gas tends to be saturated.
引文
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[14]杨宏民,王兆丰,任子阳.煤中二元气体竞争吸附与置换解吸的差异性及其置换规律[J].煤炭学报,2015,40(7):1550-1554.YANG Hongmin,WANG Zhaofeng,REN Ziyang.Differences between competitive adsorption and replacement desorption of binary gases in coal and its replacement laws[J].Journal of China Coal Society,2015,40(7):1550-1554.(in Chinese)
[15]杨宏民,冯朝阳,陈立伟.煤层注氮模拟实验中的置换—驱替效应及其转化机制分析[J].煤炭学报,2016,41(9):2246-2250.YANG Hongmin,FENG Zhaoyang,CHEN Liwei.Analysis of replacement-displacement effect and its change mechanism on simulation experiment of nitrogen injection into coal seam[J].Journal of China Coal Society,2016,41(9):2246-2250.(in Chinese)
[2]Clarkson C R,Bustin R M.Binary gas adsorption/desorption isotherms:effect of moisture and coal composition upon carbon dioxide selectivity over methane[J].International Journal of Coal Geology,2000,42(4):241-272.
[3]杨宏民.井下注气驱替煤层甲烷机理及规律研究[D].焦作:河南理工大学,2010.YANG Hongmin.Study on mechanism and characteristics laws of displacement coalbed methane by underground gas injection[D].Jiaozuo:Henan Polytechnic University,2010.(in Chinese)
[4]郑尚超,代志旭.气体驱替在提高瓦斯抽采率中的创新与应用[J].煤矿安全,2008,39(8):22-24.ZHENG Shangchao,DAI Zhixu.Innovation and application of gas displacement to improve gas drainage rate[J].Safety in Coal Mines,2008,8:22-24.(in Chinese)
[5]Teng T,Wang J G,Gao F,et al.Complex thermal coal-gas interactions in heat injection enhanced CBM recovery[J].Journal of Natural Gas Science and Engineering,2016,34:1174-1190.
[6]Yang H,Xu J,Peng S,et al.Large-scale physical modelling of carbon dioxide injection and gas flow in coal matrix[J].Powder Technology,2016,294:449-453.
[7]张美红,吴世跃,李川田.煤系地层注入CO2开采煤层气质交换的机理[J].煤炭学报,2013,38(7):1196-1200.ZHANG Meihong,WU Shiyue,LI Chuantian.Mass exchange mechanism of coalbed methane exploitation by CO2injection in coal measure strata[J].Journal of China Coal Society,2013,38(7):1196-1200.(in Chinese)
[8]王永康.注二氧化碳驱替甲烷实验及数值模拟分析[D].徐州:中国矿业大学,2016.WANG Yongkang.Experiment and numerical simulation analysis of displacing CH4by CO2injection[D].Xuzhou:China University of Mining and Technology,2016.(in Chinese)
[9]Frédérick G,Eric P,Aurélien L.CO2injection in a coal seam:insights from the European CARBOLAB project with focus on water geochemical monitoring[J].Energy Procedia,2014,63(4):5836-5848.
[10]Qu H,Liu J,Chen Z,et al.Complex evolution of coal permeability during CO2injection under variable temperatures[J].International Journal of Greenhouse Gas Control,2012,9:281-293.
[11]徐龙君,刘成伦,鲜学福.注入增产法提高煤层气采收率的理论探讨[J].重庆大学学报,2000,23(6):42-44.XU Longjun,LIU Chenglun,XIAN Xuefu.Study on the mechanism of increasing coal-bed methane production by gas injection[J].Journal of Chongqing Unversity,2000,23(6):42-44.(in Chinese)
[12]Syed A,Durucan S,Shi J Q,et al.Flue gas injection for CO2storage and enhanced coalbed methane recovery:mixed gas sorption and swelling characteristics of coals[J].Energy Procedia,2013,37(2):6738-6745.
[13]Lafortune S,Adelise F,Lahaie F,et al.Monitoring a 120-kg CO2injection in a coal seam with continuous gas and microseismic measurements(European RFCS CARBOLAB research project)[J].Energy Procedia,2014,63:4464-4472.
[14]杨宏民,王兆丰,任子阳.煤中二元气体竞争吸附与置换解吸的差异性及其置换规律[J].煤炭学报,2015,40(7):1550-1554.YANG Hongmin,WANG Zhaofeng,REN Ziyang.Differences between competitive adsorption and replacement desorption of binary gases in coal and its replacement laws[J].Journal of China Coal Society,2015,40(7):1550-1554.(in Chinese)
[15]杨宏民,冯朝阳,陈立伟.煤层注氮模拟实验中的置换—驱替效应及其转化机制分析[J].煤炭学报,2016,41(9):2246-2250.YANG Hongmin,FENG Zhaoyang,CHEN Liwei.Analysis of replacement-displacement effect and its change mechanism on simulation experiment of nitrogen injection into coal seam[J].Journal of China Coal Society,2016,41(9):2246-2250.(in Chinese)