| Edge-bottom water exit in all the gas reservoirs in general, under the normal circumstances, water in the form of small droplets will be brought to the ground when the natural gas is exploited. With the further development of gas wells, the content of water in the wells is increasing day by day, the gas production rate will be reduced dramatically and the flowing ability of gas wells will be weakened. Because of the above reasons, the water cannot be carried to the ground by the gas and comeback to the downhole, eventually forming liquid loading. Liquid loading is an unavoidable problem that all the countries in the world face with. There is no “silver bullet” that will solve liquid loading. The problem will be relieved through developing the technology of deliquification. Vortex tool is a new and effective method for dewatering to enhance production and extend the flowing lift of gas wells. The development of vortex tool has been mature in other countries, while CNPC introduced this technology in 2011 and used vortex tools to existing oil and gas wells in China as soon as possible. Vortex tools, in conjunction with gas lift, saw beneficial increases in oil and gas production along with enhanced water removal, but they cannot work efficiently in all of gas wells. Therefore, this study will focus on the swirl characteristics of the vortex tool and optimizing the parameters to enhance the efficiency of dewatering.This study adopts sectional calculation method to simulate the working condition of vortex tool in the bottom of gas well, getting the flow characteristics of gas-liquid two-phase flow. According to the simulation results and analysis, the vortex tool takes a disorganized two-phase flow and creates an organized vortex flow, slinging the heavier water toward the wall of oil tube and making gas flow in the middle of the tube. The effect of gas-liquid separation may be maintained for thousands of meters by inertia.Then, calculation changes the boundary conditions by control variable method to simulate different conditions in the gas well and find the factors which can influence the vortex tool. Firstly, the results of different water fraction inlet show that the role of vortex tool will attenuation with the increasing of the water fraction. Secondly, the study changes the inlet velocity of gas-liquid two-phase flow, there is a positive correlation between the effect of vortex tool and the increase in velocity. Finally, two linear formulas which can reflect the relationships between different conditions and the vortex tool were fit.Meanwhile, the geometric parameters of the vortex tool are optimized in this paper so that the vortex tool can be adapted to the different states in the different gas wells. Because the important part of vortex tool is the helical segment, the structural parameters optimization work aimed at the spiral line. Firstly, the numbers of coils are changed at the same of spiral line length. One of the helical pitch is 240 mm, the other one is 120 mm. It is found that at the same of spiral length the bigger the value of helical pitch is, the less effective the vortex tool is. Secondly, the result of changing the spiral line’s cross-sectional shape is that the trapezoid cross section is the best shape between trapezoid, rectangle and circle. Finally, according to analysis the different length of spiral line, the calculation displays that there is a positive correlation between the length of spiral line and the dewatering of vortex tool. |
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