考虑含水率影响的煤岩变形及渗透率模型
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摘要
煤矿开采深度不断增加,煤层瓦斯含量升高导致动力灾害逐渐增多,给煤矿安全开采带来严峻考验。对于瓦斯在煤层中流动的研究一直以来都备受关注,其中渗透率正是影响煤层中瓦斯流动的关键参数之一。因此,为准确模拟开采环境变化导致的煤岩变形及渗透特性变化,利用含瓦斯煤热-流-固耦合三轴伺服渗流装置,开展不同含水条件下孔隙压力升高过程中煤岩渗透特性的试验研究,建立考虑含水率的吸附方程和吸附-渗透率模型,探讨含水率和孔隙压力共同作用对煤岩变形及渗透特性的影响。研究结果表明:①孔隙压力升高过程中,径向应变及轴向应变随孔隙压力的升高均呈降低趋势,瓦斯流量的变化呈上升趋势,煤基质由于吸附瓦斯产生膨胀变形,体积应变逐渐减小。②当含水率恒定时,随着孔隙压力的升高,瓦斯吸附量随孔隙压力增大先增大而后趋于平缓,产生的吸附变形的变化趋势与其相同;当孔隙压力恒定时,煤岩的吸附量和吸附变形均随着含水率的增大而减小。③在恒定含水率条件下,煤岩渗透率曲线随孔隙压力的升高先减小后趋于平缓;而在相同的孔隙压力条件下,随含水率的增加,煤岩渗透率整体逐渐减小,而且含水率越大孔隙压力对渗透率的影响越弱,水分子对渗透率的影响越强。④构建了考虑含水率的吸附量计算方程,并在此基础上进一步构建考虑含水率煤岩吸附-渗透率模型,其中所计算的渗透率值与试验所测结果基本一致,反映了煤岩渗透率变化规律。
The depth of coal mining is increasing,and the increase of gas content in coal seams leads to the gradual increase of dynamic disasters, which brings severe challenges to the safe production of coal mines. Research on the flow of gas in coal seams has always been a concern and the permeability is one of the key parameters affecting gas flow in coal seams. With the application of the coal containing gas heat-fluid-solid coupling device of three axis servo seepage,it can simulate the deformation and seepage characteristics of coal mining caused by the environment through the experimental studies on the permeability of the process of the coal when the pore pressure are under different saturated conditions. Then considering moisture content, the authors establishes an adsorption equation and adsorption-permeability model so as to model the common effect of water content and pore pressure on the deformation and permeability characteristics of coal. The results show that : ① in the process of pore pressure increase, the radial strain and axial strain decrease with the pore pressure increases,and the change of gas flow increases. Due to gas adsorption, coal matrix swells,and the volumetric strain decreases gradually.② When the water content is constant,and with the increase of pore pressure,the gas adsorption capacity increases first and then levels off. The coal gas adsorption capacity and deformation decrease with the increase in moisture content when the pore pressure is constant.③ Under constant moisture conditions,coal permeability curve decreases first and then levels off with the pore pressure increase. Under a constant pore pressure, with the increase of moisture content of coal, the permeability decreases gradually, the higher moisture content of pore pressure, the less effect on the permeability by pore pressure, the stronger effect on permeability by water molecules. ④ The calculation formula of the adsorption amount considering the water content is constructed, and on this basis,the coal adsorption-permeability model considering the water content is further constructed. The calculated permeability value is basically consistent with the experimental results, which reflects the variation law of coal permeability.
The depth of coal mining is increasing,and the increase of gas content in coal seams leads to the gradual increase of dynamic disasters, which brings severe challenges to the safe production of coal mines. Research on the flow of gas in coal seams has always been a concern and the permeability is one of the key parameters affecting gas flow in coal seams. With the application of the coal containing gas heat-fluid-solid coupling device of three axis servo seepage,it can simulate the deformation and seepage characteristics of coal mining caused by the environment through the experimental studies on the permeability of the process of the coal when the pore pressure are under different saturated conditions. Then considering moisture content, the authors establishes an adsorption equation and adsorption-permeability model so as to model the common effect of water content and pore pressure on the deformation and permeability characteristics of coal. The results show that : ① in the process of pore pressure increase, the radial strain and axial strain decrease with the pore pressure increases,and the change of gas flow increases. Due to gas adsorption, coal matrix swells,and the volumetric strain decreases gradually.② When the water content is constant,and with the increase of pore pressure,the gas adsorption capacity increases first and then levels off. The coal gas adsorption capacity and deformation decrease with the increase in moisture content when the pore pressure is constant.③ Under constant moisture conditions,coal permeability curve decreases first and then levels off with the pore pressure increase. Under a constant pore pressure, with the increase of moisture content of coal, the permeability decreases gradually, the higher moisture content of pore pressure, the less effect on the permeability by pore pressure, the stronger effect on permeability by water molecules. ④ The calculation formula of the adsorption amount considering the water content is constructed, and on this basis,the coal adsorption-permeability model considering the water content is further constructed. The calculated permeability value is basically consistent with the experimental results, which reflects the variation law of coal permeability.
引文
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[13]刘永茜,张浪,李浩荡,等.含水率对煤层气渗流的影响[J].煤炭学报,2014,39(9):1840-1844.LIU Yongqian,ZHANG Lang,LI Haodang,et al. Influence of moisture content on coalbed methane seepage[J]. Journal of China Coal Society,2014,39(9):1840-1844.
[14]冯增朝,赵东,赵阳升.块煤含水率对其吸附性影响的试验研究[J].岩石力学与工程学报,2009,28(S2):3291-3295.FENG Zengchao, ZHAO Dong, ZHAO Yangsheng. Experimental study on influence of moisture content of lump coal on its adsorption[J]. Chinese Journal of Rock Mechanics and Engineering,2009,28(S2):3291-3295.
[15]尹光志,蒋长宝,许江,等.煤层气储层含水率对煤层气渗流影响的试验研究[J].岩石力学与工程学报,2010,30(S2):3401-3406.YIN Guangzhi, JIANG Changbao, XU Jiang, et al. Experimental study on the effect of coalbed methane reservoir water cut on coalbed methane percolation[J]. Chinese Journal of Rock Mechanics and Engineering,2010,30(2):3401-3406.
[16] TANG X,RIPEPI N,STADIE N P,et al. A dual-site Langmuir equation for accurate estimation of high pressure deep shale gas resources[J]. Fuel,2016,185:10-17.
[17]杨兆彪,秦勇,高弟,等.超临界条件下煤层甲烷视吸附量、真实吸附量的差异及其地质意义[J].天然气工业,2011,31(4):13-16.YANG Zhaobiao,QIN Yong,GAO Di,et al. Difference between apparent and true adsorption quantity of coalbed methane under condition and their geological significance[J]. Nature Gas Industry,2011,31(4):13-16.
[18]张国华,梁冰,毕业武.水锁对含瓦斯煤体的瓦斯解吸的影响[J].煤炭学报,2012,37(2):253-258.ZHANG Guohua, LIANG Bing, BI Yewu. Effect of water lock on gas desorption of gas-bearing coal body[J]. Journal of China Coal Society,2012,27(6):253-258.
[19] CHEN D,PAN Z,LIU J,et al.Modeling and simulation of moisture effect on gas storage and transport in coal seams[J]. Energy&Fuels,2012,26(3):1695-1706.
[20] TIAN H, LI T, ZHANG T, et al. Characterization of methane adsorption on overmature Lower Silurian-Upper Ordovician shales in Sichuan Basin, southwest China:Experimental results and geological implications[J]. International Journal of Coal Geology,2016,156:36-49.
[21]李波波,杨康,徐鹏,等.力热耦合条件下煤岩渗透率模型研究[J].中国安全科学学报,2017,27(6):139-144.LI Bobo,YANG Kang,XU Peng,et al. Research on model for permeability of coal under stress and temperature coupling condition[J]. China Safety Science Journal,2017,27(6):139-144.
[22]李波波,杨康,袁梅,等.不同温度下孔隙压力对煤岩渗流特性的影响机制[J].地球科学,2017,42(8):1403-1412.LI Bobo, YANG Kang,YUAN Mmei,et al. The mechanism of influ-ence of pore pressure on the percolation characteristics of coal and rock under different temperatures[J]. Earth Science,2017,42(8):1403-1412.
[23]许江,彭守建,尹光志,等.含瓦斯煤热流固耦合三轴伺服渗流装置的研制及应用[J].岩石力学与工程学报,2010,29(5):907-914.XU Jiang,PENG Shoujian,YIN Guangzhi,et al. Development and application of triaxial servocontrolled seepage equipment for thermofluid-solid coupling of coal containing methane[J]. Chinese Journal of Rock Mechanics and Engineering,2010,29(5):907-914.
[24]刘震,李增华,杨永良,等.水分对煤体瓦斯吸附及径向渗流影响试验研究[J].岩石力学与工程学报,2014,33(3):586-593.LIU Zhen,LI Zenghua,YANG Yongliang,et al. Experimental study on the effect of moisture on coal gas adsorption and radial seepage[J]. Chinese Journal of Rock Mechanics and Engineering,2014,33(3):586-593.
[2] CLARKSON C R. Production data analysis of unconventional gas wells:review of theory and best practices[J]. International Journal of Coal Geology,2013,109:101-146.
[3]唐巨鹏,潘一山,李成全,等.有效应力对煤层气解吸渗流影响试验研究[J].岩石力学与工程学报,2006,25(8):1563-1568.TANG Jupeng,PAN Yishan,LI Chengquan,et al. Experimental study on effect of effective stress on desorption and seepage of coalbed methane[J]. Chinese Journal of Rock Mechanics and Engineering,2006,25(8):1563-1568.
[4]袁梅,许江,李波波,等.气体压力加卸载过程中无烟煤变形及渗透特性的试验研究[J].岩石力学与工程学报,2014,33(10):2138-2146.YUAN Mei,XU Jiang,LI Bobo,et al. Experimental study of permeability and deformation of anthracite during process of gaseous loading-unloading[J]. Chinese Journal of Rock Mechanics and Engineering,2014,33(10):2138-2146.
[5]李佳伟,刘建锋,张泽天,等.瓦斯压力下煤岩力学和渗透特性探讨[J].中国矿业大学学报,2013,42(6):888-894.LI Jiawei,LIU Jianfeng,ZHANG Zetian,et al. Investigation on mechanical properities and permeability of coal under gas pressure[J].Journal of China University of Mining and Technology,2013,42(6):888-894.
[6]许江,曹偈,李波波,等.煤岩渗透率对孔隙压力变化响应规律的试验研究[J].岩石力学与工程学报,2013,32(2):225-230.XU Jiang, CAO Jie, LI Bobo, et al. Experimental research on response law of permeability of coal to pore pressure[J]. Chinese Journal of Rock Mechanics and Engineering,2013,32(2):225-230.
[7]赵阳升,胡耀青,杨栋,等.三维应力下吸附作用对煤岩体气体渗流规律影响的试验研究[J].岩石力学与工程学报,1999,18(6):651-653.ZHAO Yangsheng,HU Yaoqing, YANG Dong,et al. Experimental study on the influence of adsorption on gas seepage in coal and rock mass under three-dimensional stress[J]. Chinese Journal of Rock Mechanics and Engineering, 1999,18(6):651-653.
[8]李志强,鲜学福,隆晴明.不同温度应力条件下煤体渗透率试验研究[J].中国矿业大学学报,2009,38(4):523-527.LI Zhiqiang, XIAN Xuefu, LONG Qingming. Experimental study on coal permeability under different temperature stress conditions[J]. Journal of the University of Mining and Technology of China,2009,38(4):523-527.
[9]聂百胜,卢红奇,李祥春,等.煤体吸附-解吸瓦斯变形特征试验研究[J].煤炭学报,2015,40(4):754-759.NIE Baisheng,LU Hongqi,LI Xiangchun,et al. Experimental study on deformation characteristics of coal adsorption-desorption gas[J].Journal of China Coal Society,2015,40(4):754-759.
[10]秦跃平,刘鹏.煤粒瓦斯吸附规律的试验研究及数值分析[J].煤炭学报,2015,40(4):749-753.QIN Yueping,LIU Peng. Experimental study and numerical analysis on adsorption law of coal particle gas[J]. Journal of China Coal Society,2015,40(4):749-753.
[11]郭平,曹树刚,张遵鹏,等.煤体吸附膨胀变形模型理论研究[J].岩土力学,2014,35(12):3467-3472.GUO Ping, CAO Shugang, ZHANG Zunpeng, et al. Study on the model of coal adsorption expansion deformation[J]. Rock and Soil Mechanics,2014,35(12):3467-3472.
[12] WANG S,ELSWORTH D,LIU J. Permeability evolution in fractured coal:the roles of fracture geometry and water-content[J]. International Journal of Coal Geology,2011,87(1):13-25.
[13]刘永茜,张浪,李浩荡,等.含水率对煤层气渗流的影响[J].煤炭学报,2014,39(9):1840-1844.LIU Yongqian,ZHANG Lang,LI Haodang,et al. Influence of moisture content on coalbed methane seepage[J]. Journal of China Coal Society,2014,39(9):1840-1844.
[14]冯增朝,赵东,赵阳升.块煤含水率对其吸附性影响的试验研究[J].岩石力学与工程学报,2009,28(S2):3291-3295.FENG Zengchao, ZHAO Dong, ZHAO Yangsheng. Experimental study on influence of moisture content of lump coal on its adsorption[J]. Chinese Journal of Rock Mechanics and Engineering,2009,28(S2):3291-3295.
[15]尹光志,蒋长宝,许江,等.煤层气储层含水率对煤层气渗流影响的试验研究[J].岩石力学与工程学报,2010,30(S2):3401-3406.YIN Guangzhi, JIANG Changbao, XU Jiang, et al. Experimental study on the effect of coalbed methane reservoir water cut on coalbed methane percolation[J]. Chinese Journal of Rock Mechanics and Engineering,2010,30(2):3401-3406.
[16] TANG X,RIPEPI N,STADIE N P,et al. A dual-site Langmuir equation for accurate estimation of high pressure deep shale gas resources[J]. Fuel,2016,185:10-17.
[17]杨兆彪,秦勇,高弟,等.超临界条件下煤层甲烷视吸附量、真实吸附量的差异及其地质意义[J].天然气工业,2011,31(4):13-16.YANG Zhaobiao,QIN Yong,GAO Di,et al. Difference between apparent and true adsorption quantity of coalbed methane under condition and their geological significance[J]. Nature Gas Industry,2011,31(4):13-16.
[18]张国华,梁冰,毕业武.水锁对含瓦斯煤体的瓦斯解吸的影响[J].煤炭学报,2012,37(2):253-258.ZHANG Guohua, LIANG Bing, BI Yewu. Effect of water lock on gas desorption of gas-bearing coal body[J]. Journal of China Coal Society,2012,27(6):253-258.
[19] CHEN D,PAN Z,LIU J,et al.Modeling and simulation of moisture effect on gas storage and transport in coal seams[J]. Energy&Fuels,2012,26(3):1695-1706.
[20] TIAN H, LI T, ZHANG T, et al. Characterization of methane adsorption on overmature Lower Silurian-Upper Ordovician shales in Sichuan Basin, southwest China:Experimental results and geological implications[J]. International Journal of Coal Geology,2016,156:36-49.
[21]李波波,杨康,徐鹏,等.力热耦合条件下煤岩渗透率模型研究[J].中国安全科学学报,2017,27(6):139-144.LI Bobo,YANG Kang,XU Peng,et al. Research on model for permeability of coal under stress and temperature coupling condition[J]. China Safety Science Journal,2017,27(6):139-144.
[22]李波波,杨康,袁梅,等.不同温度下孔隙压力对煤岩渗流特性的影响机制[J].地球科学,2017,42(8):1403-1412.LI Bobo, YANG Kang,YUAN Mmei,et al. The mechanism of influ-ence of pore pressure on the percolation characteristics of coal and rock under different temperatures[J]. Earth Science,2017,42(8):1403-1412.
[23]许江,彭守建,尹光志,等.含瓦斯煤热流固耦合三轴伺服渗流装置的研制及应用[J].岩石力学与工程学报,2010,29(5):907-914.XU Jiang,PENG Shoujian,YIN Guangzhi,et al. Development and application of triaxial servocontrolled seepage equipment for thermofluid-solid coupling of coal containing methane[J]. Chinese Journal of Rock Mechanics and Engineering,2010,29(5):907-914.
[24]刘震,李增华,杨永良,等.水分对煤体瓦斯吸附及径向渗流影响试验研究[J].岩石力学与工程学报,2014,33(3):586-593.LIU Zhen,LI Zenghua,YANG Yongliang,et al. Experimental study on the effect of moisture on coal gas adsorption and radial seepage[J]. Chinese Journal of Rock Mechanics and Engineering,2014,33(3):586-593.