Plunger Lift Optimization
- _ JPT staff
- Document ID
- Society of Petroleum Engineers
- Journal of Petroleum Technology
- Publication Date
- August 1996
- Document Type
- Journal Paper
- 720 - 722
- 1996. Society of Petroleum Engineers
- 6 in the last 30 days
- 161 since 2007
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Plunger lift is one of the best options for low-productivity, high gas/liquid ratio (GLR) wells. Advantages are zero input energy and efficient removal of paraffin and scale depositions. The main disadvantage is a greater requirement for continuous monitoring.
A well producing by conventional plunger lift (Fig. 1) operates cyclically. During the buildup period, the flowline is kept closed. Liquid accumulates at the bottom of the well, and wellhead pressures continuously increase as gas accumulates in the tubing and annulus. After a set time, the flowline opens and a liquid slug, driven by gas expansion below the plunger, is produced to the surface. The main role of the plunger is to mitigate liquid fallback to the bottom of the well. Several electronic controllers for plunger-lift wells are available on the market. Usually, their logic consists of adjusting the buildup and afterflow times on the basis of the measurement of plunger rise velocity However, this may not always be the best approach.
Good estimates of possible well production rates are very important when considering lift alternatives for a particular well. Several prediction models have been suggested. None, however, accurately account for all the phenomena involved. Points of controversy include liquid accumulation at the bottom of the well during buildup and the flow of fluids around the plunger during slug production.
To study several aspects of plunger-lift operation, a small-scale experimental facility was built and a simple hydrodynamic model was developed. This paper discusses the results obtained, pointing out important factors that have been neglected in the past. An extensive literature review determined that neither the possibility nor the consequences of liquid accumulation in the tubing below the plunger or in the annulus during buildup have been addressed. Afterflow time is also an important parameter for well optimization but has not been considered in the dynamic models developed. This work attempts to clarify some of these points.
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