Abstract: Gas produced from a reservoir tends to have liquid-phase material with it, which can accumulate in the wellbore over time when the transporting energy is low enough. The liquid thus accumulated will cause additional hydrostatic pressure onthe reservoir, resulting in a continued reduction of available
transportation energy and affecting the production capacity. In some cases, it even causes gas well to die. Many formulas related to the determination of critical rate for continuous removal of liquids from gas well have been proposed. Two of the models,as proposed by Min LI and Turner et al, respectively, are compared in this paper. The comparative study includes: (1) The shape of liquid droplets entrained in high velocity stream; (2)The drag coefficient; (3) The terminal velocity and critical rate formulae; (4) Comparative study with field data. For the easier application purpose, simplified formulas for the calculation of critical rate and production rate are also deduced and given in the paper.

Key words: natural gas, load-up, droplet, terminal velocity, critical rate