基于流-固-热耦合的煤层瓦斯抽采数值模拟研究
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摘要
为了提高煤层瓦斯抽采效果预测的准确性,揭示瓦斯抽采过程中煤层各参数的变化规律,基于煤岩结构和瓦斯煤层内运移特征,结合岩体力学、渗流力学、传热学相关理论,建立了煤层瓦斯抽采的流-固-热耦合模型,进行了单裸竖直钻井瓦斯抽采数值模拟,结果表明:所建模型解算结果与工程实际相吻合,能够满足工程需要;在瓦斯抽采过程中煤层温度、瓦斯压力和产气速率均随着抽采时间的增加而减小,瓦斯抽采活动对煤层温度的变化有着很大影响;由于瓦斯吸附量减少和温度降低引起的煤基质应变降低值大于煤层压力降低引起应变增高值,瓦斯抽采影响范围内煤体渗透率不断增高,但受煤层瓦斯运移、解吸速度的影响,煤体渗透率增高速率不断减缓。
In order to improve the predicted accuracy of coal seam gas extraction,the variation law of coal seam parameters for gas drainage is revealed. Based on the characteristics of coal structure and gas movement,rock mechanics,percolation theory mechanics and heat transfer mechanics are introduced to establish the fluid-solid-thermal coupling model. Numerical simulation of gas extraction in single vertical drilling is carried out. The results are consistent with the engineering practice,which can meet the engineering requirements. The coal seam temperature,gas pressure and gas production rate decrease with the increase of pumping process. The gas drainage activity has a great influence on the change of coal seam temperature. The decrease of gas adsorption quantity and temperature caused the decrease of matrix of coal is much bigger than that of caused by the decrease of coal seam pressure. The permeability of coal in the range of gas drainage is increasing,affected by gas movement speed and desorption rate,the increased rate of coal permeability slows down.
In order to improve the predicted accuracy of coal seam gas extraction,the variation law of coal seam parameters for gas drainage is revealed. Based on the characteristics of coal structure and gas movement,rock mechanics,percolation theory mechanics and heat transfer mechanics are introduced to establish the fluid-solid-thermal coupling model. Numerical simulation of gas extraction in single vertical drilling is carried out. The results are consistent with the engineering practice,which can meet the engineering requirements. The coal seam temperature,gas pressure and gas production rate decrease with the increase of pumping process. The gas drainage activity has a great influence on the change of coal seam temperature. The decrease of gas adsorption quantity and temperature caused the decrease of matrix of coal is much bigger than that of caused by the decrease of coal seam pressure. The permeability of coal in the range of gas drainage is increasing,affected by gas movement speed and desorption rate,the increased rate of coal permeability slows down.
引文
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[3]凡永鹏,王钰博.塔山矿特厚煤层综放面采空区瓦斯治理措施研究[J].中国安全科学学报,2016,26(12):116-121.
[4]马念杰,李季,赵希栋,等.深部煤与瓦斯共采中的优质瓦斯通道及其构建方法[J].煤炭学报,2015,40(4):742-748.
[5]凡永鹏,穆晓刚,师超.“U+I”型采煤工作面瓦斯抽采与浮煤自燃耦合研究[J].中国安全生产科学技术,2017,13(5):96-102.
[6]袁亮,郭华,李平,等.大直径地面钻井采空区采动区瓦斯抽采理论与技术[J].煤炭学报,2013,38(1):1-8.
[7]王兆丰,田富超,赵彬,等.羽状千米长钻孔抽采效果考察试验[J].煤炭学报,2010,35(1):76-79.
[8]齐庆新,季文博,元继宏,等.底板贯穿型裂隙现场实测及其对瓦斯抽采的影响[J].煤炭学报,2014,39(8):1552-1558.
[9]梁冰,袁欣鹏,孙维吉.本煤层顺层瓦斯抽采渗流耦合模型及应用[J].中国矿业大学学报,2014,43(2):208-213.
[10]赵国景,步道远.煤与瓦斯突出的固─流两相介质力学理论及数值分析[J].工程力学,1995(2):1-7.
[11]徐涛,唐春安,宋力,等.含瓦斯煤岩破裂过程流固耦合数值模拟[J].岩石力学与工程学报,2005(10):1667-1673.
[12]陈立伟,杨天鸿,杨宏民,等.软、硬煤残余瓦斯含量差异性研究[J].东北大学学报(自然科学版),2015,36(7):1037-1041.
[13]秦跃平,刘鹏.煤层瓦斯流动模型简化计算误差分析[J].中国矿业大学学报,2016,45(1):19-26.
[14]Zhu W C,Wei C H,Liu J,et al.A model of coal-gas interaction under variable temperatures[J].International Journal of Coal Geology,2011,86(2/3):213-221.
[15]Wu Y,Liu J,Elsworth D,et al.Dual poroelastic response of a coal seam to CO2injection[J].International Journal of Greenhouse Gas Control,2009,4(4):668-678.
[16]Li S,Fan C,Han J,et al.A fully coupled thermal-hydraulic-mechanical model with two-phase flow for coal bed methane extraction[J].Journal of Natural Gas Science and Engineering,2016,33:324-336.
[17]陶云奇.含瓦斯煤THM耦合模型及煤与瓦斯突出模拟研究[D].重庆大学,2009.
[18]杨新乐,任常在,张永利,等.低渗透煤层气注热开采热-流-固耦合数学模型及数值模拟[J].煤炭学报,2013,38(6):1044-1049.
[19]范超军,李胜,罗明坤,等.基于流-固-热耦合的深部煤层气抽采数值模拟[J].煤炭学报,2016,41(12):3076-3085.
[20]吴宇.煤层中封存二氧化碳的双重孔隙力学效应研究[D].中国矿业大学,2010.