Analysis of the effect of the borehole length on the efficiency of coal-bed#br#
methane exploitation
MA Bo1,2,3,XU Jiang1,2,3,LIU Longrong1,2,3,MING Jinke3,YUAN Jing3,SU Xiaopeng1,2,3
(1. State Key Laboratory of Coal Mine Disaster Dynamics and Control,Chongqing University,Chongqing 400044,China;
2. State and Local Joint Engineering Laboratory of Methane Drainage in Complex Coal Gas Seam,Chongqing University,Chongqing 400044,China;3. College of Resources and Environmental Science,Chongqing University,Chongqing 400044,China)
Abstract:The physical simulation about the coal-bed methane(CBM) exploitation under 3D stress state was conducted with a multi-field coupling test system developed in-house. The development of gas pressure under the different borehole lengths was analyzed. The results show that the gas pressure decreases rapidly near the center of the borehole under the different borehole lengths. The rate of pressure drop is high at the beginning and then decreases gradually. With the increase of the borehole length,the area with high pressure gradient increases significantly,which leads to the rise of gas desorption rate and productivity. On the cross sectional plane of borehole,the pressure contours are ring shaped with the center located at the borehole,indicating that the gas flows from the coal to the borehole. On the horizontal plane,the pressure contours present the funnel shaped distribution around the symmetry axis of the borehole. Although the length of the borehole has limited influence on the occurrence time of the danger elimination area of gas outburst,the time needed to prevent the gas outburst is greatly reduced with the increase of the borehole length. Because of the high stress and the low rate of gas desorption in the coal seam area of stress concentration,more time is needed for the gas production to eliminate the outburst danger than in the other areas.
马 波1, 2,3,许 江1, 2,3,刘龙荣1, 2,3,明金科3,袁 璟3,苏小鹏1,2,3. 抽采长度对煤层气开采效果的影响分析[J]. 岩石力学与工程学报, 2017, 36(1): 175-185.
MA Bo1,2,3,XU Jiang1,2,3,LIU Longrong1,2,3,MING Jinke3,YUAN Jing3,SU Xiaopeng1,2,3. Analysis of the effect of the borehole length on the efficiency of coal-bed#br#
methane exploitation. , 2017, 36(1): 175-185.
张智峰. 煤层钻孔瓦斯抽采效果影响因素的实验研究[硕士学位论文][D]. 焦作:河南理工大学,2012.(ZHANG Zhifeng. Experiments and analysis about influence factors on coal seam gas extraction[M. S. Thesis][D]. Jiaozuo:Henan Polytechnic University,2012.(in Chinese))
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