Liquid loading in jet-lifted gas wells producing through annular channels is difficult to predict because the inner tubing changes the flow area, wall confinement, gas–liquid interfacial shear distribution, and liquid-film reversal behavior. To address this problem, this study develops a mechanistic critical liquid-carrying model for gas-well annuli by coupling droplet entrainment in the gas core with liquid-film reversal on both the inner and outer annular walls. A vertical gas–liquid flow experiment was conducted in an annular test section to investigate flow-pattern evolution and pressure-gradient response under gas flow rates of 0.1–250 m3/h and liquid flow rates of 0.1–2.5 m3/h. The experimental observations show that liquid loading in annuli is characterized by nonuniform dual-wall liquid-film thickening, local film fallback, and interaction between upward-moving and downward-moving liquid films. Based on these observations, the proposed model incorporates annular geometric parameters, dual-wall liquid-film thickness distribution, droplet entrainment fraction, gas–liquid interfacial shear, liquid-film gravity, and wall friction. The model was evaluated using laboratory data, published annular-flow data, and field production data from annular gas wells. The predicted critical gas velocities showed good agreement with experimental and literature data, with most errors within ±20%. Field-data validation further showed that the proposed model correctly identified 39 of 44 annular-production cases, corresponding to a misclassification rate of 11.3%, which was lower than that of the Wallis, Belfroid, Barnea, and Turner–Hubbard–Duckler (THD) models. These results indicate that the proposed model provides a physically based and field-applicable method for predicting liquid loading and supporting production optimization in jet-lifted annular gas wells.
Shi et al. (Mon,) studied this question.