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对煤层气合层排采井之间产气效果的差异性进行研究.基于排采数据和产出剖面测井解释结果,对大宁—吉县地区古驿背斜西翼5#,8#煤的供液能力差异及其对合采井产气效果的影响进行了研究分析,认为5#,8#煤之间存在的较大供液量差异在排采过程中有利于减轻低产水层应力敏感效应和速度敏感效应对渗透率的伤害,供液量大的8#煤对供液量低的5#煤起到了间接保护作用.研究结果表明:与层间供液量差异小的井相比,层间供液量差异大的井水量相对较大,投产4a后井底压力才降至2 MPa左右,气量缓慢增加至1 000m3/d以上,井底压力下降速度和产气速度均较缓慢,降低了应力敏感效应和速度敏感效应对煤层渗透率的伤害,利于保持高产稳产;由于层间供液能力及供液量的差异,排采过程中近井地带的压降传递速度不一致,井筒内的少量液量会倒灌进5#煤,使5#煤近井地带压力获得一定恢复,降低应力敏感伤害的同时,上、下煤层近井地带压降速度重新恢复一致,井筒内液面和压力继续维持现有的下降速度,利于压降范围继续扩大.
Based on the data of production extraction and log interpretation of output profile, the paper analyzes the difference of gas production effect between coalbed methane co-production wells, The difference of coal supply capacity and its influence on the gas production effect of the co-production well are analyzed and analyzed. It is considered that the large difference of the liquid supply between 5 # and 8 # coal is beneficial to reduce the low production aquifer Stress-sensitive and velocity-sensitive effects on the permeability damage, 8 # coal with a large amount of liquid has an indirect protective effect on 5 # coal with low liquid volume.The results show that: Compared with the well water volume with large difference between layers, the downhole pressure dropped to about 2 MPa and the gas volume slowly increased to over 1 000 m3 / d. The downhole pressure drop rate and gas production rate Slow and reduce the stress-sensitive and velocity-sensitive effects of coal seam permeability damage, which will help to maintain high and stable production; due to the difference between the liquid supply capacity and the amount of liquid, near the wellbore during the discharge pressure drop transmission speed inconsistent , A small amount of fluid in the wellbore will be poured into 5 # coal, so that the pressure near the well 5 # coal A certain recovery, reduce stress sensitivity injury while on the near wellbore area under the coal drop speed to regain consistency, the wellbore fluid level and pressure continue to maintain the current rate of decline, which will help to continue to expand the scope of the pressure drop.