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Experimental investigation of acoustic atomization in liquid loading horizontal gas wells
Al Munif, Eiman
Al Munif, Eiman
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2021
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Abstract
Enhancing the production in liquid loading natural gas wells using acoustic liquid atomizers tool is proposed as a possible artificial lift method. The more liquid converted to droplets, the more available gas to carry the liquid to the surface resulting in an increase in production. The acoustic atomizer was selected to be the atomization device as it can create very small droplets at certain frequencies leading to a mist flow. The contribution of this research includes obtaining experimental data using different laboratory procedures for horizontal and slightly inclined tubing. Two-phase (gas and water) streams along the test section and injection lines are joined to the test section to introduce gas and water at desired rates. An installed ultrasonic atomizer inside the test section is used for a better understanding of the atomization mechanism as an artificial lift technique. Several experiments with variation of the factors influencing the acoustic properties are tested. Different liquid and gas rates are injected, four different frequencies, two different flow pipe inclination angles, and two different acoustic device orientations. The results showed that when using frequencies of 62 and 62.5 kHz, the results were almost identical for horizontal and slightly inclined pipe. Both frequencies reduced liquid film accumulation by 1% at lower (0.001 m/s) and higher (0.0168 m/s) liquid velocities while gas velocity was kept at 14 m/s. The performance of the acoustic tool was highly dependent on the orientation of the tool inside the flowing loop due to its atomizer geometry, shape and size. Sprayers facing up (0o, original case) helped the droplets to be carried by the gas since the gas occupies the top portion of the pipe and did not block the atomizer. The sprayers failed to work while facing the bottom of the pipe (180o). Water started accumulating around the sprayers, plugging the atomizer and hindering it from working. Using an orientation of 90o (sprayers facing sideways) gave better results and positive impact in reducing the liquid film level. The efficiency of the tool decreases in slightly inclined wells. As more liquid quantity accumulated in the well, the atomization technique seems to be slow in reducing the liquid film height. Using four stages of sprayers was an extremely reserved approach in a 6 inch pipe. The CFD results showed that water liquid droplets of size 30 μm follow the pathway along the tool surface due to low mass of the droplets and high air velocity. This phenomenon is called wall impingement where the droplets are very small and clustering on the wall. The 200 and 300 μm water liquid droplets kept their inertial high chaotic movements in all directions within the computational domain due to the increased weight of the droplets where they withstand back pressure from high turbulent air velocity and tend to keep their inertial turbulent movement. Comparison between the experiments and the CFD computation shows that generating a droplet size of 30 μm gives lower improvement in reducing liquid film height. However, generating 200 or 300 microns predict higher improvement. In reality, having larger size droplets could reduce the droplet impingement but it might have the risk of falling back.This research presents a set of diverse experimental data to confirm acoustic atomization can be used as a possible artificial lift technique. The technique shows 1-4% improvement which can be experimental error or in experimental control. In addition, the device used in the lab needs more improvement to work as efficiently as other artificial lift techniques to enhance the production. This investigation can improve liquid loading well cases without the need to use chemicals. This technique has never been used in the oil and gas industry and continued evaluation of such a method is a vital addition to the oil and gas industry as it will help enhance the production and provide a possible new artificial lift technique.
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