Experimental and Numerical Simulation Study on Continuous Liquid Carrying in Wellbore of Water-Producing Gas Wells

Abstract

In the developed gas fields in China, most of the gas reservoirs belong to different degrees of water-bearing gas reservoirs. Formation water or condensate will be produced in the process of gas reservoir development. If the produced liquid can not be discharged in time, it will accumulate at the bottom of the well, and when it is serious, it will cause water flooding to stop production. Therefore, how to carry liquid continuously in the process of natural gas production is very important. In the past, scholars believed that as long as there was no liquid accumulation at the bottom of the well, the gas well would have continuous liquid carrying capacity. In this paper, a visual experimental frame with a total height of 16 m is established, compressed air and water are used as experimental media (gas-liquid ratio > 10000) to simulate the physical phenomenon of continuous drainage and liquid accumulation in gas wells. The parameters such as wellhead pressure, wellhead temperature, injection gas volume and experimental liquid volume are tested. The actual shape of droplets in high speed air flow is captured by modern technical means, and the mathematical model of continuous liquid carrying is established according to the force analysis of the actual physical model. In this paper, the influence of temperature and pressure on continuous liquid carrying in gas wells is calculated by using the model formula. At the same time, the sensitivity analysis of the important parameters of 7 wells in western Sichuan gas field is carried out, and the regularity of continuous liquid carrying in natural gas wells is obtained. That is: When the liquid production is small, the pressure loss in the wellbore is small, but the temperature loss is large. The temperature becomes the dominant factor affecting the liquid carrying capacity, and the maximum critical flow rate in the wellbore appears near the wellhead. With the increase of liquid production, the temperature loss is small and the pressure loss is large. The pressure becomes the dominant factor affecting the liquid carrying capacity, and the maximum critical flow rate in the wellbore appears near the bottom of the well. This also shows that the maximum critical flow rate of low-pressure gas wells is easy to appear at the bottom of the well, while the maximum critical flow rate of high pressure gas wells is easy to appear near the wellhead. The research results are of great significance for scientific research and teaching as well as field application.