Quantifying a new horizontal well gas anchor performance
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Abstract
Downhole gas separation in horizontal well has been one of the most important research areas in the oil and gas industry for decades. Separating free gas from gas-liquid mixture in the horizontal part of a well before the gas reaches a rod pump system in the vertical part will highly improve the efficiency of the pump. Free gas effects range from lower pump efficiency to reduction in oil production of a well. A new horizontal well gas anchor has been designed and tested experimentally to investigate its separation performance. The test facility used for the experiment is a transparent closed flow loop with horizontal wellbore configurations. Air and water were allowed to flow simultaneously creating a mixture at the inlet of the lateral section of the flow loop. The experiments were conducted in two folds: 1) With the tool in flow loop and 2) Without the tool in the flow loop. The new horizontal well gas anchor has a bull plug at the end, which breaks the wave produced by the mixture and creates a more stable mixture flow that enables gas separation. Also, the tool creates a tortuous path for the gas-liquid mixture and separates gas bubbles in liquid phase of the mixture.
Results from the experiments show that the tool could potentially separate 90 – 100% gas from the gas-liquid mixture given that the tool is fully submerged in the liquid phase of the mixture. Additionally, the separation of gas from the mixture was attained for stratified flow pattern and a superficial gas velocity (v_SG) below the established critical (v_SG) of 1.4 m/s. The gas separation phenomenon was also observed for experiments that the tool was removed from the flow loop. Separation existed when the inlet of the tubing was fully submerged in the liquid phase. Nonetheless, the bare tubing could not break the wave created by the gas-liquid mixture as in the case of bull plug of the tool. In addition, the upscale analysis was performed to predict the tool performance in the field condition. This allows proper design and installation of the new tool in the field condition.