地层供液能力差异对煤层气合层排采的影响——以大宁—吉县地区古驿背斜西翼为例  

Difference in liquid supply capacity of coal seams and its influence on multi-layer drainage of coalbed methane:Taking the west limb of Guyi anticline in Daning-Jixian region as an example

作　　者：巢海燕[1,2] 王延斌[1] 葛腾泽 侯伟 李彦飞 

机构地区：[1]中国矿业大学(北京)地球科学与测绘工程学院,北京100083 [2]中石油煤层气有限责任公司,北京100028

出　　处：《中国矿业大学学报》2017年第3期606-613,共8页Journal of China University of Mining & Technology

基　　金：国家科技重大专项(2016ZX05066001;2016ZX05042002)

摘　　要：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.Differences in the coalbed methane production of different multi-layer drainage wells in the west limb of Guyi anticline in Daning-Jixian region was studied.Based on production data and results of production profile logging interpretation,difference in liquid supply capacity of No.5and No.8coal seams and its influence on coalbed methane production of commingled producing well were analyzed.During the drainage process,big differences in liquid supply quantity of No.5and No.8coal seams will help reduce the permeability damage caused by stress sensitivity and fluid velocity sensitivity.No.8coal seams with strong liquid supply quantity protects No.5coal seams indirectly.The results indicate that water production of wellswith big difference in liquid supply quantity of two seams is larger than that of wells with small difference.The bottom hole pressure of wells with big difference in liquid supply quantity drop to 2 MPa or so after four-year drainage,and gas production increases to 1 000m3/d or above slowly,reducing the permeability damage caused by stress sensitivity and fluid velocity sensitivity and helping maintain high and stable yield.Due to differences in liquid supply capacity and quantity,pressure drop transmission speed of the two seams near the borehole zones is inconsistent,causing small amount of liquid intruding into the No.5coal seam and the pressure recovers to some extent.When the damage caused by the stress sensitivity is reduced,the pressure drop transmission speed returns to a consistent state.The working fluid level and pressure in well bore continue to maintain the existing rate of decline,which will further enlarge the pressure drop range.

关 键 词：煤层气 合层排采 供液量差异 压降传递 渗透率 

分 类 号：P618.11[天文地球—矿床学]