Weiqi Fu (Master of Science in Petroleum Engineering)
Gas Well Liquid Loading Onset and Plunger Lift Modelling
Summary, Conclusions and Recommendations
Based on Zhang et al. (2003) unified model, liquid loading behavior in gas wells is studied in this thesis. The predictions of liquid loading are analyzed for different well inclinations including 900, 75 0 and 600 . Superficial liquid velocities of 0.01, 0.05 and 0.1 m/s are selected for comparison. The minimum pressure gradient and liquid film velocity reversal concepts are examined as liquid loading onset criteria in gas wells. Compared with experimental data of Yuan (2011), the liquid film velocity reversal method gives better predictions on liquid loading for the studied well inclination angles.
A plunger lift mechanistic model is developed to simulate the plunger lift working process and predict the production rates in gas wells with plunger lift operation. The model is based on the approaches presented by Lea (1982) and Gasbarri and Wiggins (2001). Improvements have been made on the equations of plunger rising and falling velocities. The present model also accounts different reservoir performances in plunger lift simulation. Oil and water cases from previous studies are used to evaluate the present model which shows more accurate and reasonable predictions of plunger rising and
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falling velocities. Further validations for this model are recommended when more field
data become available.