Volume 66

A Liquid-Carrying Boundary Model for Gas Wells under Spiral Flow Conditions and Its Experimental Validation Tian He, Guoqing Han, Peidong Mai ,Ting Hu

Abstract

Gas wells in long-term production commonly encounter liquid accumulation, among which insufficient liquid-carrying capacity is one of the key factors restricting productivity enhancement and stable operation. As a novel drainage tool with a simple structure and convenient operation, the spiral flow device can significantly enhance liquid removal performance and effectively mitigate liquid buildup when a stable spiral flow regime is sustained within the wellbore. However, most conventional liquid-carrying models for gas wells are established on the assumptions of droplet entrainment or annular liquid film flow. These models fail to adequately capture the force characteristics and boundary transition mechanisms of liquid films under spiral flow conditions, leading to considerable deviations in predicting the liquid-carrying boundary and making it difficult to accurately determine the applicability and failure limits of spiral flow tools. To address this issue, this study develops a spiral flow liquid film carrying-boundary model by analyzing the dynamic behavior of liquid films and incorporating the mechanisms of shear instability and film fallback. Laboratory visualization experiments were conducted to compare the predictive performance of the proposed model with conventional critical liquid-carrying models, including those of Turner, Li Min, and Wang. The results demonstrate that the proposed model achieves an average prediction error of only 7.9%, which is markedly superior to conventional models. Further sensitivity analysis reveals that smaller pipe diameters, lower spiral angles, narrower liquid film thicknesses, and higher pressure conditions are more favorable for maintaining stable spiral flow. This study not only deepens the theoretical understanding of liquid-carrying mechanisms in gas wells but also provides theoretical and technical guidance for the design optimization and field application of spiral flow tools.

Keywords Spiral flow, Drainage and gas recovery,Critical liquid carrying model,Flow regime transition