New modeling techniques for two-piece plunger lift components



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Texas Tech University


The two piece plunger (a steel ball below and a hollow cylinder) seals the tubing when the ball is on the bottom of the cylinder. The plunger is designed to carry liquids from a producing gas well to prevent liquid loading. As such it can lift liquids when the components are together with gas pressure providing the lifting energy. When the two combined components reach the surface, the liquid is produced and the ball is pushed away from the cylinder to begin to fall against the flow. The cylinder is retained on the ball push rod until a short shut-in period of the well. Then the cylinder falls against the flow and hopefully combines with the ball at the bottom of the well to collect more liquids in the gas well and carry them to the surface with the combined ball and cylinder. There are many instances where using this plunger results in production increases. However in some cases, it appears to have a lesser effect.

Results of testing show that above certain rates, the components will not fall against the flow in the well. Test results, and the result of drag models to fit the test data are extended to show the potential user what the allowable rates are from the well, before the individual components are predicted to fall more slowly or to be unable to fall in the well, thereby making application impossible without a temporary reduction in the flow rate. The results should allow the user to be able to better use the two piece plunger in a wider range of application conditions to remove liquids from a flowing gas well.



Gas fields, Gas wells, Gas lift pumps