New Techniques for Plunger Lift in Conventional and Nonconventional Gas

Abstract

The interest in and demand for natural gas has dramatically shifted the focus for many operators in the past few years. Plunger lift, which for many years was viewed as a last resort, and somewhat of a nuisance, has gained an all time high in popularity, and effectiveness and applicability. Most of the guesswork in evaluating candidates has been replaced with exotic programs that combine Nodal analysis with performance based calculations. In recent years both equipment and applications have improved, and the production range of plunger lift now includes many wells previously not possible to produce with plunger lift. Here we will examine the new technology utilized in tracking, evaluating, and troubleshooting plunger lift wells. Also several case studies on where previously difficult production is now commonplace, will be presented. Introduction For years plunger lift was viewed as more of an art than a science. Selection of appropriate well candidates was as much from a "feeling" about the well's suitability. Some basic rules of thumb were often used as basic criteria. This, coupled with field experience, was the determination used in well selection. Still today, by many, rules of thumb and field knowledge are frequently used in the selection process. There are however, more and more programs and technology being utilized in the selection process. Sophisticated programs that do complex nodal analysis have been used for years for many of the other types of artificial lift, such as gas lift. Until recently, such programs have been virtually ignored for the plunger lift process. As the popularity of plunger lift continues to grow, so does the utilization of technology. It is now much more of a common practice to combine a nodal analysis with a pressure analysis to make determinations. This type analysis not only gives the operator better tools to determine a well's suitability, but also can help decide the type operation, and assist in equipment selection. The range of wells that can be improved by utilization of plunger lift is much broader today than ever. On both ends of the production scale, plunger lift is now applied to improve production and operations. From high-speed plungers in high-rate wells, to multiple plungers in the same tubing string for marginal and difficult to produce wells, the application process continues to improve and expand along with the technology used in the process of selection. Applications The typical candidates for a plunger lift system are;Gas wells with liquid loading problemsHigh ratio oil wellsIntermittent gas lift wells with fallback problemsParaffin control In North America there are 10's of thousands of wells being produced by plunger lift, outside of North America, there are very few wells produced in this manner. The principal reason is the popularity and market for Natural Gas. As the gas markets have grown and developed in other parts of the world, the applicability of plunger lift has also grown. In the life of most gas wells, there comes the time when liquid loading will occur. It is at this time in the life of a well that plunger lift becomes appropriate. Gas wells and high ratio oil wells Today, plunger lift is installed much earlier in the life of the well than had been practiced in the past. Before, it wasn't until there were significant loading problems that plunger lift was considered. Now, as wells approach critical velocity, this technique is being effectively employed.