煤层气直井排采初期水力模型的建立

Coalbed Methane Vertical Well Production Hydraulic Model Building

为研究在地质资料不足的情况下煤层气井产气量的预测模型,利用Theis公式、Jacob公式对煤层气储层的导水系数、降落漏斗影响半径进行计算,利用Langmuir公式对煤层气临界解吸压力计算,并通过积分计算煤层气井的解吸半径。通过建立大佛寺煤层气直井排采过程的水力模型,进行单井产气量模拟,结果与实际排采曲线吻合程度较好。我们发现:不同排采阶段井底压力与产水量呈线性关系;降落漏斗影响半径与液面降深呈对数关系,与排采时间呈幂指数关系;在客观因素上,导水系数、影响半径对产气量的影响最大。

In order to study the prediction model of gas production of CBM wells in the drainage process with the shortage of geological data, we calculated the transmissibility of reservoir and the conical de-pression influence radius of water cone by using Theis formula and Jacob formula, calculated the critical desorption pressure by using Langmuir formula and calculated the desorption radius of CBM wells by integral. We founded the simulation results and the actual production curve with a better fit degree by model building and gas production fitting of single well. The result showed that there is a linear relationship between the bottom hole pressure in different production stages and water production. The conical depression influence radius of water cone and level drawdown shows a logarithm relationship, and it shows a exponential relationship with the production time. The transmissibility and the influence radius have the greatest effect on the gas production in the objective factors.