Need a Lift? A Rotary Gear Pump, an ESP System Without the ESP Pump

Abstract Electric submersible pump (ESP) systems have over many decades proven themselves as a reliable Industry leading lift system. However, there are limitations to the ESP lift system particularly with reliability and performance in high volume deep unconventional wells with steep decline curves and high amounts of free gas which present multiple challenges that require reliable solutions to enhance the performance and run life of the ESP system and increase overall production. This paper presents the "new innovative next thing" in artificial lift. A robust high volume, low speed positive displacement rotary gear pump (RGP) that has the ability to operate reliably throughout ranges untouched with centrifugal pumps, delivers optimal production and does so in a cost-effective manner in comparison to a conventional ESP system. The main challenge for long economical production is high decline rate – typically production rates drop 50-80% of initial rates after the first year. The primary reasons for such reservoir behavior: transient inflow effect, no pressure maintained and fracture deterioration. Producing a wide and flexible range of production rates with high efficiency is a significant challenge to artificial lift selection. With the Industry trending to reduce costs by drilling reduced ID horizontal wellbores with long lateral lengths, this poses a challenge particularly in integrating a life-time one artificial lift system design to capture both the high and low ends of the decline curves that can be handled by ESP systems particularly in confined wellbore architectures. This coupled with operational issues such as pump cavitation or gas locking, high motor operating temperatures, and abrasion/erosional issues due to excessive gas slugging and solids production led to the development of an innovative positive displacement pump. This paper describes the steps undertaken in designing, testing, and planning a pilot for a prototype rotary gear pump which replaces the centrifugal pump component of an ESP system while addressing all of the functional requirements for successful field implementation.