各向异性和非均质性对煤层抽采钻孔瓦斯渗流的影响作用机制
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摘要
为提高深部煤层瓦斯抽采效率,研究抽采钻孔周围煤体的瓦斯渗流规律十分关键。文中基于煤体的各向异性和非均质性,考虑煤体应力变形场和瓦斯渗流场的交叉耦合作用,分析了煤层抽采中水力割缝钻孔周围瓦斯压力以及渗透率的时空演化规律。结果表明:煤体的各向异性和非均质性影响割缝钻孔周围的瓦斯渗流规律。对于瓦斯压力的变化,平行层理方向瓦斯压力降幅大于垂直层理方向,抽采影响范围分布呈现"椭圆形",煤体各向异性表征明显。对于渗透率的变化,平行层理方向的煤层渗透率高于垂直层理方向,抽采初期渗透率的增加幅度较快,随后逐渐减缓,渗透率变化曲线呈现不规则"锯齿形",煤体非均质性表征明显。将数值模拟结果与杨柳矿4~#钻场瓦斯抽采的实际监测情况相互对比,现场实测的瓦斯抽采情况与模拟得到情况基本吻合,从而验证了数值模拟的合理性及工程适用性。
In order to improve gas drainage efficiency of deep coal seams,it is very important to study the gas seepage law of coal bodies around the extraction borehole.Based on the anisotropy and heterogeneity of coal body,considering the cross-coupling effect of coal stress-deformation field and gas seepage field,the space-time evolution law of gas pressure and permeability around the borehole in the extraction process was analyzed.The results show that the anisotropy and heterogeneity of the coal affect the gas flow law around the borehole.For the change of gas pressure,the gas pressure decrease in the parallel bedding direction is larger than that in the vertical bedding direction,and the distribution of the influence range of the extraction is "elliptic",and the anisotropy of the coal body is obviously characterized.For the change of permeability,the permeability of coal seam in parallel bedding direction is higher than that of vertical bedding.The increase of permeability in the initial stage of extraction is faster,and then gradually slows down.The curve of permeability shows irregular "zigzag" and coal body heterogeneity is clearly characterized.The numerical simulation results were compared with the actual monitoring situation of the gas drainage in the 4~# drilling site of Yangliu Mine.The actual gas extraction in the field is basically consistent with the simulated situation,which verifies the rationality of the numerical simulation and the applicability of the engineering practice.
In order to improve gas drainage efficiency of deep coal seams,it is very important to study the gas seepage law of coal bodies around the extraction borehole.Based on the anisotropy and heterogeneity of coal body,considering the cross-coupling effect of coal stress-deformation field and gas seepage field,the space-time evolution law of gas pressure and permeability around the borehole in the extraction process was analyzed.The results show that the anisotropy and heterogeneity of the coal affect the gas flow law around the borehole.For the change of gas pressure,the gas pressure decrease in the parallel bedding direction is larger than that in the vertical bedding direction,and the distribution of the influence range of the extraction is "elliptic",and the anisotropy of the coal body is obviously characterized.For the change of permeability,the permeability of coal seam in parallel bedding direction is higher than that of vertical bedding.The increase of permeability in the initial stage of extraction is faster,and then gradually slows down.The curve of permeability shows irregular "zigzag" and coal body heterogeneity is clearly characterized.The numerical simulation results were compared with the actual monitoring situation of the gas drainage in the 4~# drilling site of Yangliu Mine.The actual gas extraction in the field is basically consistent with the simulated situation,which verifies the rationality of the numerical simulation and the applicability of the engineering practice.
引文
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[11] 鲁义,申宏敏,秦波涛,等.顺层钻孔瓦斯抽采半径及布孔间距研究[J].采矿与安全工程学报,2015,32(1):156-162.LU Yi,SHEN Hong-min,QIN Bo-tao,et al.Gas drainage radius and borehole distance along seam[J].Journal of Mining and Safety Engineering,2015,32(1):156-162.
[12] LU Yi-yu,GE Zhao-long,YANG Feng,et al.Progress on the hydraulic measures for grid slotting and fracking to enhance coal seam permeability[J].International Journal of Mining Science and Technology,2017,27(10):867-871.
[13] ZHOU Ai-tao,WANG Kai,FAN Ling-peng,et al.Gas-solid coupling laws for deep high-gas coal seams[J].International Journal of Mining Science and Technology,2017,27(4):675-679.
[14] WEI Jian-ping,LI Bo,WANG Kai,et al.3D numerical simulation of boreholes for gas drainage based on the pore-fracture dual media[J].International Journal of Mining Science and Technology,2016,26(4):739-744.
[15] 林柏泉,刘厅,杨威.基于动态扩散的煤层多场耦合模型建立及应用[J].中国矿业大学学报,2018,47(1):32-39.LIN Bai-quan,LIU Ting,YANG Wei.Solid-gas coupling model for coal seams based on dynamic diffusion and its application[J].Journal of China University of Mining & Technology,2018,47(1):32-39.
[16] Anggara Ferian,Sasaki Kyuro,Rodrigues Sandra.The effect of megascopic texture on swelling of a low rank coal in supercritical carbon dioxide[J].International Journal of Coal Geology,2014,125:45-56.
[17] TAN Yu-ling,PAN Zhe-jun,LIU Ji-shan,et al.Experimental study of impact of anisotropy and heterogeneity on gas flow in coal.Part I:Diffusion and adsorption[J].Fuel,2018,232:444-453.
[18] 岳高伟,王宾宾,曹汉生,等.结构异性煤层顺层钻孔方位对有效抽采半径的影响[J].煤炭学报,2017(S1):138-147.YUE Gao-wei,WANG Bin-bin,CAO Han-sheng,et al.Influence of effective drainage radius by borehole orientation along seam with anisotropic permeability[J].Journal of China Coal Society,2017(S1):138-147.
[19] WANG Lin-lin,Vandamme M,Pereira J M,et al.Permeability changes in coal seams:The role of anisotropy[J].International Journal of Coal Geology,2018,199:52-64.
[20] 魏晨慧.热流固耦合条件下煤岩体损伤模型及其应用[D].沈阳:东北大学,2012.WEI Chen-hui.Damage model for coal and rock under coupled thermal-hydraulic-mechanical conditions and its application[D].Shenyang:Northeastern University,2012.
[21] 于永江.煤体非均质随机裂隙模型及渗流-应力耦合分析[D].沈阳:辽宁工程技术大学工程力学,2010.YU Yong-jiang.Heterogeneous random crack model and coupled process analysis of seepage field and stress field in coal mass[D].Shenyang:Liaoning Technical University,2010.
[22] LIU Ji-shan,CHEN Zhong-wei,Elsworth Derek,et al.Linking gas-sorption induced changes in coal permeability to directional strains through a modulus reduction ratio[J].International Journal of Coal Geology,2010,83:21-30.
[23] Harpalani S,Schraufnagel A.Measurement of parameters impacting methane recovery from coal seams[J].International Journal of Mining and Geological Engineering,1990,8(4):369-384.
[24] Robertson Eric P,Christiansen Richard L.Modeling laboratory permeability in coal using sorption-induced-strain data[J].SPE Reservoir Evaluation & AMP,Engineering,2007(3):260-269.
[25] ZHAO Yang,LIN Bai-quan,LIU Ting,et al.Gas flow field evolution around hydraulic slotted borehole in anisotropic coal[J].Journal of Natural Gas Science and Engineering,2018,58:189-200.
[26] LIU Ting,LIN Bai-quan,YANG Wei.Impact of matrix-fracture interactions on coal permeability:Model development and analysis[J].Fuel,2017,207:522-532.
[27] ZHANG Hong-bin,LIU Ji-shan,Elsworth D.How sorption-induced matrix deformation affects gas flow in coal seams:A new FE model[J].International Journal of Rock Mechanics and Mining Sciences,2008,45(8):1226-1236.
[2] ZOU Quan-le,LIN Bai-quan,ZHENG Chun-shan,et al.Novel integrated techniques of drilling-slotting-separation-sealing for enhanced coal bed methane recovery in underground coal mines[J].Journal of Natural Gas Science and Engineering,2015,26:960-973.
[3] 袁亮.我国深部煤与瓦斯共采战略思考[J].煤炭学报,2016,41(1):1-6.YUAN Liang.Strategic thinking of simultaneous exploitation of coal and gas in deep mining[J].Journal of China Coal Society,2016,41(1):1-6.
[4] 曹偈,孙海涛,戴林超,等.煤与瓦斯突出动力效应的模拟研究[J].中国矿业大学学报,2018,47(1):113-120,154.CAO Jie,SUN Hai-tao,DAI Lin-chao,et al.Simulation research on dynamic effect of coal and gas outburst[J].Journal of China University of Mining & Technology,2018,47(1):113-120,154.
[5] 季淮君,李增华,杨永良,等.基于瓦斯流场的抽采半径确定方法[J].采矿与安全工程学报,2013,30(6):917-921.JI Huai-jun,LI Zeng-hua,YANG Yong-liang,et al.Drainage radius measurement based on gas flow field[J].Journal of Mining and Safety Engineering,2013,30(6):917-921.
[6] 林柏泉,赵洋,刘厅,等.水力割缝煤体多场耦合响应规律研究[J].西安科技大学学报,2017,37(5):662-667.LIN Bai-quan,ZHAO Yang,LIU Ting,et al.Coupling response law of multi-field in coal seam after hydraulic slotting[J].Journal of Xi’an University of Science and Technology,2017,37(5):662-667.
[7] 肖峻峰,樊世星,卢平,等.近距离高瓦斯煤层群倾向高抽巷抽采卸压瓦斯布置优化[J].采矿与安全工程学报,2016,33(3):564-570.XIAO Jun-feng,FAN Shi-xing,LU Ping,et al.Layout parameter optimization of highly-located drainage roadway along seam for controlling gas with pressure relief from close-distance methane-rich seam group[J].Journal of Mining and Safety Engineering,2016,33(3):564-570.
[8] Candela Thibault,Brodsky Emily E,Marone Chris,et al.Laboratory evidence for particle mobilization as a mechanism for permeability enhancement via dynamic stressing[J].Earth and Planetary Science Letters,2014,392:279-291.
[9] PAN Zhe-jun,Connell Luke D.Modelling permeability for coal reservoirs:A review of analytical models and testing data[J].International Journal of Coal Geology,2012,92:1-44.
[10] 尹光志,李小双,赵洪宝,等.瓦斯压力对突出煤瓦斯渗流影响试验研究[J].岩石力学与工程学报,2009,28(4):697-702.YIN Guang-zhi,LI Xiao-shuang,ZHAO Hong-bao,et al.Experimental study of effect of gas pressure on gas seepage of outburst coal[J].Chinese Journal of Rock Mechanics and Engineering,2009,28(4):697-702.
[11] 鲁义,申宏敏,秦波涛,等.顺层钻孔瓦斯抽采半径及布孔间距研究[J].采矿与安全工程学报,2015,32(1):156-162.LU Yi,SHEN Hong-min,QIN Bo-tao,et al.Gas drainage radius and borehole distance along seam[J].Journal of Mining and Safety Engineering,2015,32(1):156-162.
[12] LU Yi-yu,GE Zhao-long,YANG Feng,et al.Progress on the hydraulic measures for grid slotting and fracking to enhance coal seam permeability[J].International Journal of Mining Science and Technology,2017,27(10):867-871.
[13] ZHOU Ai-tao,WANG Kai,FAN Ling-peng,et al.Gas-solid coupling laws for deep high-gas coal seams[J].International Journal of Mining Science and Technology,2017,27(4):675-679.
[14] WEI Jian-ping,LI Bo,WANG Kai,et al.3D numerical simulation of boreholes for gas drainage based on the pore-fracture dual media[J].International Journal of Mining Science and Technology,2016,26(4):739-744.
[15] 林柏泉,刘厅,杨威.基于动态扩散的煤层多场耦合模型建立及应用[J].中国矿业大学学报,2018,47(1):32-39.LIN Bai-quan,LIU Ting,YANG Wei.Solid-gas coupling model for coal seams based on dynamic diffusion and its application[J].Journal of China University of Mining & Technology,2018,47(1):32-39.
[16] Anggara Ferian,Sasaki Kyuro,Rodrigues Sandra.The effect of megascopic texture on swelling of a low rank coal in supercritical carbon dioxide[J].International Journal of Coal Geology,2014,125:45-56.
[17] TAN Yu-ling,PAN Zhe-jun,LIU Ji-shan,et al.Experimental study of impact of anisotropy and heterogeneity on gas flow in coal.Part I:Diffusion and adsorption[J].Fuel,2018,232:444-453.
[18] 岳高伟,王宾宾,曹汉生,等.结构异性煤层顺层钻孔方位对有效抽采半径的影响[J].煤炭学报,2017(S1):138-147.YUE Gao-wei,WANG Bin-bin,CAO Han-sheng,et al.Influence of effective drainage radius by borehole orientation along seam with anisotropic permeability[J].Journal of China Coal Society,2017(S1):138-147.
[19] WANG Lin-lin,Vandamme M,Pereira J M,et al.Permeability changes in coal seams:The role of anisotropy[J].International Journal of Coal Geology,2018,199:52-64.
[20] 魏晨慧.热流固耦合条件下煤岩体损伤模型及其应用[D].沈阳:东北大学,2012.WEI Chen-hui.Damage model for coal and rock under coupled thermal-hydraulic-mechanical conditions and its application[D].Shenyang:Northeastern University,2012.
[21] 于永江.煤体非均质随机裂隙模型及渗流-应力耦合分析[D].沈阳:辽宁工程技术大学工程力学,2010.YU Yong-jiang.Heterogeneous random crack model and coupled process analysis of seepage field and stress field in coal mass[D].Shenyang:Liaoning Technical University,2010.
[22] LIU Ji-shan,CHEN Zhong-wei,Elsworth Derek,et al.Linking gas-sorption induced changes in coal permeability to directional strains through a modulus reduction ratio[J].International Journal of Coal Geology,2010,83:21-30.
[23] Harpalani S,Schraufnagel A.Measurement of parameters impacting methane recovery from coal seams[J].International Journal of Mining and Geological Engineering,1990,8(4):369-384.
[24] Robertson Eric P,Christiansen Richard L.Modeling laboratory permeability in coal using sorption-induced-strain data[J].SPE Reservoir Evaluation & AMP,Engineering,2007(3):260-269.
[25] ZHAO Yang,LIN Bai-quan,LIU Ting,et al.Gas flow field evolution around hydraulic slotted borehole in anisotropic coal[J].Journal of Natural Gas Science and Engineering,2018,58:189-200.
[26] LIU Ting,LIN Bai-quan,YANG Wei.Impact of matrix-fracture interactions on coal permeability:Model development and analysis[J].Fuel,2017,207:522-532.
[27] ZHANG Hong-bin,LIU Ji-shan,Elsworth D.How sorption-induced matrix deformation affects gas flow in coal seams:A new FE model[J].International Journal of Rock Mechanics and Mining Sciences,2008,45(8):1226-1236.
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