Study On Gas-Liquid Flow Dynamic At Different Angles

With the continuous improvement of gas well development technology,horizontal wells have been widely used in various gas fields at home and abroad because of the large reservoir drainage area and the effective improvement of single well productivity.However,in the process of gas well development,there is a common problem of liquid accumulation in the wellbore.Due to the unclear understanding of the liquid-carrying mechanism of inclined pipes,the existing methods for predicting liquid loading in gas wells have certain limitations in actual production application,which leads to a lack of effective guidance in the design of drainage and production.Therefore,the ability to define the mechanism of liquid carrying and the prediction method of liquid loading in gas well is of great importance for determining the time of drainage and optimizing the related production technology.In this paper,the following studies on the dynamics of gas-liquid two-phase flow at different angles were carried out:(1)The author have investigated the methods for predicting liquid loading in various gas wells,analyzed and summarized the problems of unclear understanding of the liquid-carrying mechanism and pointed out the development direction in the aspects of experiment and theory in predicting liquid loading for gas wells;(2)The experiment of gas-liquid two-phase transient flow under different angles was carried out.The experimental media were air and water.The dynamic of gas-liquid flow under different inclination angles,gas-liquid flow rates and pipe diameters was studied by using the visual experimental device and high-precision data acquisition system;(3)The experimental results showed that the actual flow pattern of liquid carrying is transition flow;the droplets cannot exist stably in the inclined tube;the essence of liquid carrying is liquid film carrying;and the liquid film is not evenly distributed along the circumference of the tube wall;the critical gas velocity increases first and then decreases with the angle increasing,and increases with the liquid volume and pipe diameter increasing while 55 ° is the most difficult liquid carrying angle;(4)Based on the Belfroid model,considering the effects of the superficial liquid velocity,pipe diameter,bottom hole flow pressure and temperature,a modified model for predicting critical gas velocity in the inclined pipe was established by fitting and modifying the experimental data.A new film model for predicting critical gas velocity in the inclined pipe was established by taking the reverse of liquid film as the starting point of liquid accumulation and considering the uneven distribution of liquid film around the inclined pipe.The applicability of the two models was evaluated and verified based on the laboratory test data and field data,which proves that the new model is reasonable to guide the field diagnosis of liquid loading in gas wells.