A simplified model to predict transient liquid loading in gas wells

Abstract

This paper presents a simplified model to predict the inception of liquid loading in gas wells and its subsequent transient phenomenon. This model enables the estimation of erratic or cease of production due to liquid loading using a simple but robust technique. This approach is validated with field data. The model described in this paper proposes the use of the so-called “nodal analysis technique” to predict liquid loading in gas wells. The approach proposed modifies the tubing performance relationship instead of using the common critical velocity or minimum pressure point concept. This modification enables the simple use of nodal analysis to accurately predict liquid loading initiation, including the amount of time required to cease production after the inception of liquid loading. The model shows good agreement field data on the prediction of liquid loading.From the modeling results and comparison with field data, it is possible to conclude that this model can provide a reasonable prediction of the liquid loading phenomena. For instance, one of the main objectives of using models to predict liquid loading is to anticipate when a gas well would start suffering from liquid loading problems, and potentially stop flowing. The use of conventional models showed a significant mismatch in the critical flow for liquid loading initiation when compared to field data while the use of the model proposed would reduce this mismatch significantly. In addition to that, the use of this simplified model also enables understanding of the main field symptoms related to liquid loading in gas wells.