Special Considerations for Electric, Submersible Pump Applications in Underpressured Reservoirs

This paper investigates the effect of electric submersible pump (ESP) performance tolerances and minor speed variations on the producing rate of wells completed in underpressured reservoirs, and presents ESP design considerations unique for the class of wells. These wells require considerable head to initiate flow and have relatively flat well-load curves. Pumps that operate near their maximum recommended rate have steep performance curves, and this is shown to minimize the effect of an underperforming pump on producing rate. Equations are developed for calculating the effects of pump performance and speed. Application requires evaluating the slopes of the pump-performance and well-load curves at design rate. The usefulness of these equations is demonstrated by practical examples. it is also demonstrated that flow stall can occur easily in underpressured reservoir applications when pumps designed to operate near their minimum recommended rate are installed.