不同产能气井携液能力的定量分析

Quantitative analysis of the capability of liquid removing from different-productivity gas wells

在老气田的生产开发过程中,井筒积液是一个非常严重的问题。为了保证气井不产生积液,国内外很多学者对气井的最小携液流量都进行了研究,建立了一系列的数学模型,但对气井产量大于临界流量时其液体能否被携带至地面的问题尚未深入探讨。为此,在井筒积液水力学分析的基础上,运用多相流理论,从垂直管柱内环雾流的动量方程出发,建立了气井最大携液量计算的数学模型,并利用VB软件实现了对该模型的求解。分析和计算结果表明:在气井产量大于最小临界携液流量的条件下,不是所有的液体都能够被携带至井口,而是存在一个最大的临界携液量。该临界携液量随着井口压力的减小而增大,随着管径的增大而减小。因此,应用气井临界携液量资料可以分析井筒积液,从而确定气井实施排水采气工艺的时机。这对于气井的稳定生产具有重要的支撑和指导作用。

Liquid loading is a serious problem in the development of mature gas fields.To avoid liquid loading in gas wells,many scholars at home and abroad have conducted their studies on the minimum unloading gas flow rate and built a series of corresponding mathematical models.However,the issue whether fluids can be taken up to the surface ground when the output of gas wells is larger than the critical flow has not yet been deeply discussed.For this reason,based on the mechanical analysis of liquid loading and by using the theory of multiphase flow,starting from the momentum equation of mist flow in the vertical pipe column,a mathematical model for calculating the maximum unloading gas rate is constructed and the corresponding solution is obtained by using VB programs.The calculation results and the corresponding analysis show that when the output of gas wells is larger than the minimum unloading gas flow rate,not all the fluids will be taken up to the wellhead.There is a maximum critical unloading gas flow rate,which will increase with the decrease of the wellhead pressure while decrease with the increase of tubing diameter.Therefore,the data about the critical unloading gas flow rate of gas wells can help engineers analyze the liquid loading.Accordingly,the timing for applying techniques of gas recovery by discharge water can be determined.This study is important in supporting and directing the stable development of gas wells.