水平井内柱状柱塞举升气液流动密封特性OA

Plunger lift technology serves as one of the key methods for ensuring the efficient drainage of liquid loading during the late production stage of horizontal wells in unconventional oil and gas reservoirs.Its core mechanism relies on the plunger to form a solid sealing interface between gas and liquid phases,thereby reducing gas channeling upward and liquid slippage to significantly enhance lift efficiency.The current research has provided a sufficient understanding on the sealing behaviors of gas-liquid flow during plunger lift in vertical wells,but lacks a quantitative description for the dynamic sealing mechanism at the gas-liquid interface in unconventional horizontal wells.This paper investigates the gas-liquid flow sealing behaviors of plunger lift within the 0°–70° well inclination angle range by means of numerical simulation,focusing on gas and liquid leakage behaviors and their impact on liquid carrying capacity.Based on the governing equations of two-phase flow dynamics,a predictive model for leakage rate is developed.In addition,the multi-phase flow mechanisms in the process of plunger lift in horizontal wells are illustrated.The following results are obtained.First,the plunger velocity dominates the leakage mode,with liquid film shear instability being the main cause of liquid leakage under high-speed conditions(>6 m/s).Second,the liquid leakage rate exhibits a non-monotonic trend of increasing firstly and then decreasing with increasing well inclination angle.Third,increased wellbore pressure can suppress gas channeling upward,but intensify liquid leakage.Fourth,the derived theoretical model quantifies the competitive relationship between pressure difference drive and shear drive during the leakage process.In conclusion,the model reveals a non-monotonic variation pattern of well inclination angle with leakage rate,and the leakage rate prediction model is established,which is conducive to guide the structural design of the plungers for horizontal wells and the optimization of plunger system,thereby improving the cyclic drainage rate of plunger in horizontal wells.What's more,the revealed dynamic sealing mechanisms can provide a theoretical basis for the sealing optimization and lift process parameter design of plungers for horizontal wells,and is of important theoretical guidance significance for the efficient production of horizontal wells in unconventional oil and gas reservoirs,as well as the stable production and output increase of gas fields.