Gas-Well Liquid-Loading-Field-Data Analysis and Multiphase-Flow Modeling

Gas-well liquid loading occurs when gas production becomes insufficient to lift the associated liquids to surface. When that happens, gas production becomes intermittent and eventually stops. In depleting gas reservoirs, the technical abandonment pressure and ultimate recovery are typically governed by liquid loading. To date, most methods for predicting liquid loading have followed Turner et al. (1969), who describe liquid loading as the point where the liquid droplets suspended in the gas flow start moving downward rather than upward. This paper presents (offshore) liquid-loading field data that exceed the Turner predicted values by an average of 40%, and analyzes the sensitivity of the liquid-loading gas rate for different well parameters. It subsequently presents the results of steady-state and transient multiphase-flow modeling, carried out to identify the influence of the same well parameters. A modified Turner expression is proposed that best fits the liquid-loading field data and broadly agrees with the results of a multiphase-flow model that uses a modified version of the Gray outflow correlation. The results of transient-flow modeling support the flow-loop observation that liquid loading occurs because of liquid-film-flow reversal rather than droplet-flow reversal. The impact of these findings on gas-well deliquefication is explored.