Long-stroke sucker-rod pumping units have definite advantages as compared to their traditional counterparts. They produce greater liquid rates with less downhole pump problems and can also increase the life of the rod string due to the reduced number of stress reversals. This article examines present-day long-stroke rod pumping methods and discusses the two main types of technologies available: the fully mechanically driven Rotaflex and the hydraulically driven DynaPump. Although several types of long-stroke pumping units were developed in the past with some success, today only two models are available.
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