An analysis of the continuous removal of liquids from gas wells

Natural gas wells producing liquid phase material along with the gas must be flowed at a gas rate sufficient to continuously remove the liquids. Otherwise these liquids will accumulate in the wellbore, restricting the flow of gas and affecting the calculations associated with standard performance tests required by most states. The minimum gas flow rate necessary to prevent accumulation is therefore significantly important to gas producers. The purpose of this thesis is to analyze the methods of liquid mass transport in a two-phase gas/liquid system flowing co-currently upward, and to establish a method of calculating the minimum gas flow rate that will carry the liquid phase material continuously up the conduit. The mass transport mechanisms in vertical tubes are developed theoretically with continuous upward moving annular liquid films, flooding countercurrent annular films and entrained liquid drop movement each treated separately. The minimum gas flow conditions for each mechanism are derived and the developments tested against field flow test data. A method of predicting the minimum gas flow rate necessary to continuously remove liquids from gas wells is presented.