New Perspective on Gas-Well Liquid Loading and Unloading

Abstract

Summary This paper discusses the multiphase-flow mechanism responsible for gas-well liquid loading. It shows that the conventional idea of droplet-flow reversal (Turner et al. 1969) does not fully describe reality and that liquid-loading observations appear more compatible with film-flow reversal. This paper subsequently explores how film-flow reversal changed views on existing gas-well liquidunloading techniques such as continuous foam injection, and it discusses new methods of gas-well deliquefication that specifically aim to delay film-flow reversal. The benefits of different types of tubing-wall modification have been evaluated through small-scale laboratory testing. Most promising, hydrophobic coating of tubing reduces the gas rate below which liquid loading occurs by approximately 50%. The benefits of hydrophobic coating are translated to representative field conditions.