低渗透气藏气水两相流井产能分析方法研究

Productivity analysis method of water and gas two-phase flow well in low permeability gas reservoirs

对于存在边水、底水及层间水的低渗透气藏,当气井产水后,出现了气水两相流动。气井产能的合理计算关系到各项开发指标的确定,有利于整个气田的高效开发。以质量守恒原理为基础,通过建立气水两相同时流动的运动方程,在定义气水两相拟压力函数和气水两相拟启动压力梯度之后,推导出考虑启动压力梯度和地层损害影响的低渗透气藏气水两相流井的三项式产能方程,并在此基础上阐明了该方程的求解方法。通过实际应用,得到了受启动压力梯度和水气质量比影响的低渗透气藏气水两相流井的流入动态关系曲线。研究表明,随启动压力梯度和水气质量比的增大,均导致气井无阻流量减小。该项研究为存在边水、底水及层间水的低渗透气藏的产能及动态分析提供了一定的理论基础。

During the well produces in lowpermeability gas reservoir,it appears the gas and water two-phase flowdue to the existence of edge water,bottom water and interlayer water.The reasonable productivity is associated with kinds of development indexes,and it is helpful for the effective development of gas field.Based on the principle of mass conservation,this paper defined pseudopressure function and threshold pressure gradient of two-phase flowof both gas and water,and deduced trinomial productivity equation of gas and water two-phase flowin lowpermeability gas reservoirs in considering threshold pressure gradient and formation damage effects.This paper expounded the method of calculating the trinomial deliverability equation.Through the analysis of actual case,the relation curves of the well that gas and water two-phase flowunder the influence of threshold pressure gradient and the water/gas quality ratio in low-permeability gas reservoirs was obtained.The research shows that with the increase of threshold pressure gradient and water/gas quality ratio,the AOF becomes small.So it provides a theory basis for gas and water two-phase flow well productivity anddynamic analysis of the well in the existence of edge water,bottomwater and interlayer water in low-permeability gas reservoirs.