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为分析煤层气井产能,基于煤层气井压裂后地层液渗流和管流模型,建立了气水两相流阶段下变裂缝变流量产气通道导流能力模型,并对排采阶段影响导流能力的因素进行了分析,提出了持液率是影响气水两相流阶段导流能力的重要因素.该模型为煤层气井产能的分析提供了重要依据.当持液率等于1时,该模型为单相水流阶段导流能力模型;当持液率等于0时,该模型为单相气体流动阶段导流能力模型;当计算模型中裂缝宽度变化函数为常数时,即为恒裂缝宽度导流能力模型;分析结果表明:煤层气井在气水两相流阶段其产气通道导流能力受持液率的影响,随着持液率增加,导流能力增加;气水两相流中水所占的比例越大其导流能力越大,即单相水流阶段比单相气体流动阶段产气通道的导流能力大,一方面煤层气的解吸产出使产气通道内持液率降低,产气通道的导流能力降低;另一方面煤层气的解吸产出时煤基质收缩,产气通道增大,其导流能力增加.故煤层气定量排采中可以设计合理的产气量使产气通道达到最佳的导流能力,以优化煤层气的排采制度.
In order to analyze the productivity of CBM wells, based on the fluid seepage and flow model of formation after fracturing of coalbed methane wells, a model of diversion capacity of gas production channel with variable flow in gas-water two-phase flow was set up and the diversion capacity , The author holds that liquid holdup is an important factor affecting the diversion capability of gas-water two-phase flow.The model provides an important basis for the analysis of CBM productivity.When the holdup is equal to 1, the model is When the liquid holdup is equal to 0, the model is a single-phase gas flow stage flow conductivity model; when the change function of the crack width is a constant in the calculation model, it is the flow conductivity of the constant crack width The results show that the diversion ability of coalbed methane wells in the gas-water two-phase flow is influenced by the liquid holdup. With the increase of the holdup rate, the diversion capability increases. The gas-water two-phase flow accounts for The larger the ratio is, the greater the diversion capability is, that is, the single-phase flow stage is larger than the single-phase gas flow stage, and on the other hand, the desorbed output of coalbed gas decreases the liquid holdup rate in the gas production channel. Gas channel diversion ability to reduce; On the other hand, when the desorption of coalbed methane is produced, the coal matrix shrinks and the gas production channel increases, and its diversion capability increases, so that the rational gas production can be designed in the quantitative gas drainage of CBM so as to achieve the optimal diversion capability , In order to optimize the CBM drainage system.