双层或多层合采是提高煤层气单井产量的重要途径。为了提高沁水盆地南部郑庄区块合采井排采效率,基于郑庄西南部现场排采数据和排采试验结果,分别提出了通过动液面降至15号煤后产量变化趋势实时判断15号煤产气能力和通过地质工程关键参数、解吸初期排采参数预测15号煤产气能力方法,同时提出了“变速排采、控压放气、高压快提、高压稳产”的双层合采井排采管控方法并在沁水盆地郑庄西南部开展了现场试验。结果表明：动液面降至15号煤后如果产量持续上升,则15号煤产气效果较好;如果产气量趋于平稳,则表明15号煤产气量较低;15号煤深测向电阻率小于1 000 Ω·m,或施工压力相对较低的井产气能力差;利用煤层气井见套压后15号煤层底的流体压力与套压数据预测各层产气能力的方法,预测结果精确度较高;新排采方法效果较好,20口试验井平均达产周期由180 d下降至140 d,缩短了22.2 %,平均单层产量由1 000 m³升至1 200 m³,提高了20 %。但试验井井间开发效果差异大,产气能力强的井稳产气量高、稳产时间长。产能预测方法和排采方法对双层合采井充分释放单井产能具有借鉴意义。

The bilayer or multilayer co-drainage is an important approach to improve the single well production. In order to improve the drainage efficiency of bilayer drainage wells in Zhengzhuang Block of southern Qinshui Basin, the drainage data and co-drainage trial data from the southwest of Zhengzhuang Block are analyzed and the method is put forward to judge the gas production capacity of No.15 coal seam in real time by the change trend of coal production after the hydrodynamic level drops below No.15 coal seam. Two methods predicting the gas production capacity of each layer by key parameters of both geology and engineering or by early desorption drainage parameters are proposed. A new drainage method is put forth and the trial is carried out in the southeast of Qinshui Basin, that is the “variable rate drainage, gas released at certain casing pressure, high-production-rate and certain stable production kept at high pressure”. The results show that if the production continues to rise after the fluid level drops below the No.15 coal seam, the gas production capacity of No.15 coal seam is high. On the contrary, it indicates that gas production of No.15 coal seam is low. When the resistivity of No.15 coal seam is less than 1 000 Ω·m or the construction pressure is low, the gas production capacity is relatively low. The data of bottom-hole flowing pressure and casing pressure of No.15 coal seam after casing pressure come out in coalbed methane well can be used effectively to predict the gas production capacity of each layer, with high prediction accuracy. The application of the new drainage method, proposed by this paper, results in 22.2 % shorter of the production-increasing cycle decreasing from 180 d to 140 d and more than 20 % increase of the average single-layer production from 1 000 m³ to 1 200 m³, compared with the old drainage method. The great difference in the development performance among the 20 wells is affected mainly by the gas production capacity of each well. The wells with higher gas production capacity have higher stable gas production and longer stable gas production time. The productivity prediction method and the co-drainage method of bilayer vertical coalbed methane wells have great reference significance to the productivity releasing of co-drainage bilayer vertical coalbed methane wells.