Liquid loading in gas wells occurs when the gas flow rate falls below a critical value due to reservoir depletion where the accompanying liquids can not be lifted up to surface. Since liquid loading has a detrimental impact on production, deliquification methods need to be employed in order to recover the production. To choose the right deliquification measures and achieve a timely deployment, it is therefore important to predict the onset of liquid loading in advance. Traditionally, the Turner correlation has been used for this purpose. However, latest published data from deviated large diameter offshore wells show that the Turner correlation can underpredict the critical gas rate by 20-200%. The operators can be misled by this prediction and are often not well prepared for tackling the liquid loading as they may think the problem is still some years away.

Liquid loading is a transient phenomenon in nature and thus needs to be described by a dynamic multiphase flow model. In the present study, instead of modifying or improving the Turner correlation, a comprehensive dynamic multiphase flow model is used to predict the onset of liquid loading. Totally fourteen offshore gas wells were simulated using the dynamic model. The predicted critical gas flow rates are validated against field data and the predictions lie within the ±20 % error margin. The effect of condensate gas ratio (CGR) on liquid loading is also investigated. The simulations show that it is possible for low CGR wells that the critical gas flow rate can decrease with the increasing CGR. This is also in line with the field observations.

This study brings forth the importance of transient multiphase flow modeling and opens new frontiers for dynamic simulation of gas well deliquification, which shall set up guidelines from dynamic point of view for implementing the right deliquification measures so that more production can be recovered when loading has happened.

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