考虑变启动压降低渗气藏产能方程的建立

The Establishment of Deliverability Equation with Consideration of Variable Threshold Pressure Drop in Low Permeability Gas Reservoir.

基于低渗透气藏非达西低速稳定渗流微分方程,推导出启动压降表达式,分析得出启动压降并非为绝对常数,而与测试产量有关,并以修正等时试井为例分析了目前产能方程的误差;通过对启动压降进行定积分的近似求解,得出考虑变启动压降的低渗透气藏新的产能方程,并提出相应的修正等时试井资料的处理方法。实际应用表明,该产能试井分析新方法具有实用价值。

The percolation mechanism in low permeability gas reservoir is different from that in common gas reservoirs.All the deliverability equations regard the additional pressure drop as constant,but this is not true in the former cases.Based on the low-speed and non-Darcy steady flow equation for low permeability gas reservoir,this paper derives an expression of threshold pressure drop,concludes that the additional pressure drop is not a constant,and has something to do with the production rate during testing;gets a new deliverability equation which takes variable threshold pressure drop into account,and provides the relevant processing method of the modified isochronal test data.Field application showed that the new deliverability equation is practically useful.