Prediction method of continuous liquid-carrying gas flow rate for highly deviated and high liquid-gas ratio gas wells

The natural gas wells in Nanpu Oilfield are of high liquid-gas ratio, and the well types are mainly directional wells and highly deviated wells. The existing liquid-carrying liquid film model does not fully consider the influence of the inclination angle, resulting in inaccurate calculation of the critical liquid-carrying gas flow rate. Based on the experiment data on the distribution of liquid film thickness of the annular flow in inclined tubes, the relationship between the thickness of the liquid film at the bottom of inclined tubes and the average thickness of the liquid film of the annular flow in vertical tubes was proposed, the empirical relational expression between the average thickness of the liquid film in the vertical pipe and the interfacial friction coefficient was determined, and a new model for predicting the critical liquid-carrying gas flow rate for wells with high inclination and high liquid-gas ratio was established. The experiment and production data show that the model is accurate and reliable, with an average error of −7.67%. This model is the development and improvement of the existing liquid-carrying theory for directional wells. The new model is helpful to improve the design quality of the tubing string for the highly deviated wells in the gas reservoir, to enhance production allocation level for gas wells, and to improve the diagnostic ability of the liquid accumulation after the gas well is put into production.