Onset and Subsequent Transient Phenomena of Liquid Loading in Gas Wells: Experimental Investigation Using a Large Scale Flow Loop

Abstract

Liquid loading in gas wells is generally described as the inability of the well to lift the co-produced liquids up the tubing, which may ultimately kill the well. There is a lack of dedicated models that can mimic the transient features that are typical of liquid loading. Improved characterization of liquid loading in gas wells and enhanced prediction of future well performance can be achieved from the measurements and analyses resulting from this project.

An experimental investigation was carried out to study the onset of liquid loading and the subsequent transient phenomena, using a large scale flow loop to visualize two-phase flow regimes, and to measure pressure and liquid holdup along a 42-m long vertical tube.

From this investigation, it is possible to conclude that liquid loading should not be characterized based on onset criteria alone, and that it may not be a wellbore-only problem, as it would seem that the reservoir also plays a key role in determining if/when/how liquid loading manifests itself.

Additionally, the results from the experimental campaign were used to compare the performance of different wellbore flow simulators. State-of-the-art simulators do not seem to fully capture the nature of liquid loading in vertical tubes. A simplified model is roposed here to evaluate the liquid transport during the transition from one flow regime to another, during the loading sequence.