Experimental and Field Investigations of Bypass Plunger Lift

Abstract

The fall and upstroke characteristics of bypass plunger are investigated for conventional and continuous flow plunger lift operations using experimental and field data. The bypass plunger's operational boundaries are compared with those of two-piece plungers. Clutch failure is also evaluated. Bypass and two-piece plungers were tested in static and dynamic conditions to compare their fall drag characteristics with two different tubing and plunger sizes. Casing pressure buildup was used to surface the bypass plunger to represent the conventional plunger lift type of operation for the upstroke tests. Continuous gas and liquid injection were used to achieve multiphase flow conditions for bypass plunger experiments. Experimental findings retrieved from the study were combined with mechanistic models to predict fall and upstroke stages of the bypass plunger in the field conditions. Multiphase flow simulator results were presented, and its effect on plunger lift mechanistic models were discussed. In the static facility, bypass plungers were found to have a higher drag coefficient, falling slower than sleeves of the same height. The drag coefficient values for 1.9-in OD and 2.34-in OD bypass and sleeves were similar, suggesting that plungers tested for a given tubing size can be extrapolated to others. The bypass plunger was suitable for conventional and continuous flow plunger lift operations. The 19.5-in bypass plunger and 9-in sleeve fall and upstroke velocities were analogous. Visual observations showed that the bypass plunger clutch mechanism may not get fully opened if the plunger does not hit the lubricator fast enough. The well test, high-frequency pressure, and plunger lift data of five wells from the Permian basin were analyzed. The continuous flow plunger-lift mechanistic models are used to estimate the bypass plunger cycle. The total cycle time and plunger run per day estimations matched with average run-time and trip-count field data. The study presents the bypass plunger lift's cycle mechanics, operational limitations, and comparison with two-piece plungers in different tubing sizes. The experimental and field data of bypass plungers, mechanistic model benchmarking, and potential bypass plunger lift applications are featured.