School of Resources and Geosciences,China University of Mining and Technology Guizhou Provincial Engineering and Technology Research Center of Coalbed Methane and Shale Gas

为了制定与土城区块煤层气合采井相适配的排采制度,基于土城区块煤层气地面抽采示范工程,结合合层排采理论与COMET3数值模拟方法,分析了区块内煤层气地质条件及生产井排采曲线特征,划分了煤层气合采井产出的5个阶段,探讨了合层排采工艺优化措施。结果表明:初期排水阶段应严格控制排水速率,保持液面高度大于450 m、流压高于4.5 MPa;憋压阶段注意控制憋压幅度,在预留一定液面高度基础上憋压;控压产气阶段重点控制流压降低速率,模拟结果显示流压日降幅控制在0.010~0.015 MPa/d排采效果最佳;控压稳产阶段动液面在第1层段停留时间不宜过长,可在0.5 MPa套压下主动缓慢暴露上部产层;产气衰减阶段需维持第3压裂段流压稳定,模拟结果显示0.7MPa作为稳压值将更有利于产气。

in order to set up a gas crainage system suitable to the caled methane combined drainage well in Tucheng Block.based on the demo projec of the coal bed methane surface drainage in Tucheng Block.in combinaton with the combined seam drainage theory and the COMET3 numericalsimulaton method.thecoledmnethane geologic conditin and the gas drainage cure features ofthe gas production well vithin the bock were analized and the optimized measures of the combinedsean drainage fechrique were discussed.Theresults showed tht the water drainage rate should be seriously controlled at the intial water drainage stage.the height of the water level should be kept over 450 m and the fowing pressure value should be over 4.5 MfPa.T7he pressure buli-up margin shauld be controlld during the pressure build-up stage and the pressure built-up should be based on the certain level heigh pre-set.The fowing pressure reduced rate should be ighly conrlled at the pessure control and gas production stage and the sirulaton results showed that adrainage effect would be best when the fiowing pressuredail reducion was conral d at 0.010~0.015 MPal d. At the pressure control and stable producion stage,the retention time of the fiowin liqud lvel at the frt ay er should not be too ong andthe upper production layer could be actively and slowly exposed under the casing pressure of 0.5 MPa.At the productio attenuation stage,the flowing pressure in the third fractring secion should be kept n stable and the sinulation resuits showed that 0.7 MPa as a stablired pressure value would be favorableto the gas production

国家自然科学基金资助项目(51204162、41272154)；贵州省科技重大专项资助项目(黔科合重大专项字[2014]6002号)；