Performance Improvement of Helical Downhole Gas-Oil Separator Using Experimental Approach

Abstract

Growing demand for a subsurface pump application to perform artificial lift in low-pressure wells increases the necessity of a high-efficiency downhole separator to prevent gas entrance in the pump. The purpose of this study is to empirically investigate the efficiency of a helical downhole separator and provide suggestions for improving its performance. To make the results more practical, dimensionless numbers governing the problem were specified using dimensional analysis and the Buckingham theorem, and a laboratory-scale separator was built. Oil and air were selected as the working fluids for this experiment. The results of the experiments showed that the separator performance was divided into three regions: inefficiency region, rapid-growth region, and nongrowth region. To increase the separator efficiency, the separator was modified by blocking the initial holes of the inner tube to provide a region for developing the prerotational effect. The modified separator showed an increase in efficiency as much as 7%. In the third step, the number of holes that were blocked at the entrance region in the first modification were distributed in the rest of the inner tube so that the total hole area remains constant. The separator efficiency, in this case, was significantly increased compared with the previous two cases by as much as twofold. It was found that the inlet design of the separator significantly affects its performance.