煤样尺度的二氧化碳驱替煤层气数值模拟
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摘要
为了实现ECBM实验研究和数值模拟结合分析,基于实验室应力条件的渗透率模型,建立了煤孔隙裂隙介质系统的CO2驱替煤层CH4的数值模型。开展了不同CO2注入压力下煤样尺度的二氧化碳驱替煤层气的数值模拟。结果表明:CO2的注入压力越大,注入后CO2从煤样末端流出所需时间越小;CO2的注入会引起煤的渗透率减小,注入压力较小时渗透率变化分为三个阶段,包括有效应力影响的阶段、CH4压力不变的阶段和CO2吸附影响阶段,但是当注入压力较大时则不存在CH4压力不变的阶段;注入压力增大,CH4产出量在注入CO2后的一定时间内有很大提高,然后在注气后期,CH4产出量反而较小。上述结果对指导室内开展ECBM实验和分析ECBM室内实验的结果具有指导意义。
In order to achieve the ECBM experimental research and numerical simulation combined analysis,based on the permeability model under the laboratory stress conditions,a numerical model of CO2-ECBM,including the pore and fracture medium system of coal,was established.Numerical simulation of CO2-ECBM at different CO2 injection pressures was carried out.The results show that the greater the injection pressure of CO2,the less time it takes for CO2 to flow out from the end of the coal after injection.The injection of CO2 will cause the permeability of coal to decrease,and when the injection pressure is small,the change of permeability will be divided into three stages,including the stage of effective stress,the stage of constant CH4 pressure,and the stage of CO2 adsorption.When the injection pressure is large,there is no stage of the stage of constant CH4 pressure.As the injection pressure increases,the CH4 output increases greatly after a certain period of time after the injection of CO2,and then the CH4 output is smaller at the later stage of gas injection.The above results are instructive for the CO2-ECBM experiments and the analysis of its experimental results.
In order to achieve the ECBM experimental research and numerical simulation combined analysis,based on the permeability model under the laboratory stress conditions,a numerical model of CO2-ECBM,including the pore and fracture medium system of coal,was established.Numerical simulation of CO2-ECBM at different CO2 injection pressures was carried out.The results show that the greater the injection pressure of CO2,the less time it takes for CO2 to flow out from the end of the coal after injection.The injection of CO2 will cause the permeability of coal to decrease,and when the injection pressure is small,the change of permeability will be divided into three stages,including the stage of effective stress,the stage of constant CH4 pressure,and the stage of CO2 adsorption.When the injection pressure is large,there is no stage of the stage of constant CH4 pressure.As the injection pressure increases,the CH4 output increases greatly after a certain period of time after the injection of CO2,and then the CH4 output is smaller at the later stage of gas injection.The above results are instructive for the CO2-ECBM experiments and the analysis of its experimental results.
引文
[1] LI X,FANG Z.Current status and technical challenges of CO2 storage in coal seams and enhanced coalbed methane recovery:an overview[J].International Journal of Coal Science&Technology,2014,1(1):93-102.
[2]梁卫国,吴迪,赵阳升.CO2驱替煤层CH4试验研究[J].岩石力学与工程学报,2010,29(4):665-673.LIANG Weiguo,WU Di,ZHAO Yangsheng.Experimental study of coalbed methane replacement by carbon dioxide[J].Chinese Journal of Rock Mechanics and Engineering,2010,29(4):665-673.
[3]梁卫国,张倍宁,韩俊杰,等.超临界CO2驱替煤层CH4装置及试验研究[J].煤炭学报,2014,39(8):1511-1520.LIANG Weiguo,ZHANG Beining,HAN Junjie,et al.Experimental study on coalbed methane displacement and recovery by super critical carbon dioxide injection[J].Journal of China Coal Society,2014,39(8):1511-1520.
[4]吴迪,刘雪莹,孙可明,等.热力作用下煤层注CO2驱替CH4试验研究[J].煤炭学报,2016,41(1):162-166.WU Di,LIU Xueying,SUN Keming,et al.Experimental research on methane displacement in coalbed by carbon dioxide under thermo-mechanical action[J].Journal of China Coal Society,2016,41(1):162-166.
[5] JESSEN K,TANG G Q,KOVSCEK A R.Laboratory and simulation investigation of enhanced coalbed methane recovery by gas injection[J].Transport in Porous Media,2008,73(2):141-159.
[6] WEI X,MASSAROTTO P,WANG G,et al.CO2sequestration in coals and enhanced coalbed methane recovery:new numerical approach[J].Fuel,2010,89(5):1110-1118.
[7] PINI R,STORTI G,MAZZOTTI M.A model for enhanced coalbed methane recovery aimed at carbon dioxide storage[J].Adsorption,2011,17(5):889-900.
[8] SHI J Q,MAZUMDER S,WOLF K H,et al.Competitive methane desorption by supercritical CO2injection in coal[J].Transport in Porous Media,2008,75(1):35-54.
[9]杨宏民,魏晨慧,王兆丰,等.基于多物理场耦合的井下注气驱替煤层甲烷的数值模拟[J].煤炭学报,2010,35(S1):109-114.YANG Hongmin,WEI Chenhui,WANG Zhaofeng,et al.Numerical simulation of coalbed methane displacement by underground gas injection based on multi-physics coupling[J].Journal of China Coal Society,2010,35(S1):109-114.
[10]王兆丰,陈进朝,杨宏民.注气驱替煤层甲烷的有效影响半径研究[J].煤炭科学技术,2012,40(9):28-31.WANG Zhaofeng,CHEN Jinchao,YANG Hongming.Study on effective influence radius of borehole air injection to remove and replace coalbed methanes in seam[J].Coal Science and Technology,2012,40(9):28-31.
[11]吴金涛,侯健,陆雪皎,等.注气驱替煤层气数值模拟[J].计算物理,2014,31(6):681-689.WU Jintao,HOU Jian,LU Xuejiao,et al.Numerical simulation of coalbed methane displacement with gas injection[J].Chinese Journal of Computational Physics,2014,31(6):681-689.
[12]王公达,REN Tingxiang,齐庆新,等.二氧化碳/氮气驱替煤层瓦斯过程的数学模型[J].岩石力学与工程学报,2016,35(S2):3930-3936.WANG Gongda,REN Tingxiang,QI Qingxin,et al.Mathematical model of coal seam methane displacement by injecting CO2/nitrogen[J].Chinese Journal of Rock Mechanics and Engineering,2016,35(S2):3930-3936.
[2]梁卫国,吴迪,赵阳升.CO2驱替煤层CH4试验研究[J].岩石力学与工程学报,2010,29(4):665-673.LIANG Weiguo,WU Di,ZHAO Yangsheng.Experimental study of coalbed methane replacement by carbon dioxide[J].Chinese Journal of Rock Mechanics and Engineering,2010,29(4):665-673.
[3]梁卫国,张倍宁,韩俊杰,等.超临界CO2驱替煤层CH4装置及试验研究[J].煤炭学报,2014,39(8):1511-1520.LIANG Weiguo,ZHANG Beining,HAN Junjie,et al.Experimental study on coalbed methane displacement and recovery by super critical carbon dioxide injection[J].Journal of China Coal Society,2014,39(8):1511-1520.
[4]吴迪,刘雪莹,孙可明,等.热力作用下煤层注CO2驱替CH4试验研究[J].煤炭学报,2016,41(1):162-166.WU Di,LIU Xueying,SUN Keming,et al.Experimental research on methane displacement in coalbed by carbon dioxide under thermo-mechanical action[J].Journal of China Coal Society,2016,41(1):162-166.
[5] JESSEN K,TANG G Q,KOVSCEK A R.Laboratory and simulation investigation of enhanced coalbed methane recovery by gas injection[J].Transport in Porous Media,2008,73(2):141-159.
[6] WEI X,MASSAROTTO P,WANG G,et al.CO2sequestration in coals and enhanced coalbed methane recovery:new numerical approach[J].Fuel,2010,89(5):1110-1118.
[7] PINI R,STORTI G,MAZZOTTI M.A model for enhanced coalbed methane recovery aimed at carbon dioxide storage[J].Adsorption,2011,17(5):889-900.
[8] SHI J Q,MAZUMDER S,WOLF K H,et al.Competitive methane desorption by supercritical CO2injection in coal[J].Transport in Porous Media,2008,75(1):35-54.
[9]杨宏民,魏晨慧,王兆丰,等.基于多物理场耦合的井下注气驱替煤层甲烷的数值模拟[J].煤炭学报,2010,35(S1):109-114.YANG Hongmin,WEI Chenhui,WANG Zhaofeng,et al.Numerical simulation of coalbed methane displacement by underground gas injection based on multi-physics coupling[J].Journal of China Coal Society,2010,35(S1):109-114.
[10]王兆丰,陈进朝,杨宏民.注气驱替煤层甲烷的有效影响半径研究[J].煤炭科学技术,2012,40(9):28-31.WANG Zhaofeng,CHEN Jinchao,YANG Hongming.Study on effective influence radius of borehole air injection to remove and replace coalbed methanes in seam[J].Coal Science and Technology,2012,40(9):28-31.
[11]吴金涛,侯健,陆雪皎,等.注气驱替煤层气数值模拟[J].计算物理,2014,31(6):681-689.WU Jintao,HOU Jian,LU Xuejiao,et al.Numerical simulation of coalbed methane displacement with gas injection[J].Chinese Journal of Computational Physics,2014,31(6):681-689.
[12]王公达,REN Tingxiang,齐庆新,等.二氧化碳/氮气驱替煤层瓦斯过程的数学模型[J].岩石力学与工程学报,2016,35(S2):3930-3936.WANG Gongda,REN Tingxiang,QI Qingxin,et al.Mathematical model of coal seam methane displacement by injecting CO2/nitrogen[J].Chinese Journal of Rock Mechanics and Engineering,2016,35(S2):3930-3936.