考虑液滴夹带的气井连续携液预测模型

在有水气藏开发过程中,随着气藏压力的降低和含水量的增加,井筒内的气相能量不足以将水携带到地面,导致井底积液,从而影响气井产量,严重时甚至压死气井,造成停产。准确预测气井临界携液流速对判断气井是否积液和优化气井配产具有重要的意义。基于液膜携液假设,通过气液两相流受力平衡分析,建立了考虑液滴夹带影响的气井连续携液预测模型。模型引入了基于临界液膜流量和临界气相流速的液滴夹带判据,并采用了考虑液膜雾化与液滴沉积动态过程影响的液滴夹带率计算公式。结合实际气井生产数据,所建立模型与现有的液膜临界流速模型的对比结果表明,该模型的预测结果与气井实际状况更加吻合,可用于气井积液的判断。

A prediction model for continuous liquid-carrying in gas wells considering droplet entrainment

In the development of water-bearing gas reservoir, with the reduction of reservoir pressure and the increase of water content, the natural gas is no longer capable of lifting liquid to surface which triggers gradual accumulation of liquid in the bottom of wellbore. Liquid loading can reduce gas production, even completely kill gas wells and stop production. Accurate prediction of critical liquid-carrying velocity has an important significance for liquid loading judgment and optimization allocation in gas well production. Through analyzing the force balance of gas-liquid two-phase flow, we established a new liquid film model which take into account the impacts of liquid entrainment, to predict the minimum gas velocity for continuous liquid-carrying in gas wells. A droplet entrainment onset criterion based on critical liquid film flow rate and critical gas velocity, and a droplet entrainment rate correlation considering the influences of liquid film atomization and droplet deposition at gas-liquid interface were employed in the model. The present and existing liquid film-based critical gas velocity models are validated and compared with the actual gas wells data. The results show that the present model agrees well with the actual state of gas wells, implying it can be used to judge the liquid loading in gas wells.