Modeling of Liquid Unloading in Vertical Gas Wells by Foam.

      Аннотация: Liquid loading of gas and gas condensate wells contributes significantly to production decline. The accumulation of liquids begins when the gas rate drops below the critical gas rate required lifting liquids out of the well to surface due to reservoir depletion, skin, back pressure effects, etc. The prevalence of foam treatment for well liquefaction has increased over the past two decades, where a surfactant is introduced to the well, allowed to mix with the wellbore liquids and agitated resulting in improved unloading characteristics with reduced fluid surface tension and liquid column density. There are two general models for gas wells unloading prediction. The first model is Droplet Model and the second model is Film Model. In droplet model critical gas velocity and rate has calculated with writing force balance for liquid droplets in pipe center. In film model has assumed gas flows in center of pipe and foam film flows on the pipe wall. The correlation that has published is a function of tubing diameter and liquid gas ratio. Now we think their model has a defect.

Ключевые слова: Gas well, Liquid Loading, foam, Critical Gas Rate, Film Model