Abstract
Progressing Cavity (PC) pumps evolved from their industrial pump origins to a diverse range of geometries and configurations that satisfy a variety of oilfield artificial lift applications including several where no other lift systems had proved effective. While these downhole PC pump designs provide options for end users, the numerous products combined with a lack of industry standardization has the potential to make pump selection and application challenging. The first part of this paper describes the fundamental PC pump geometry parameters along with various other design parameters and provides context for how they are incorporated in downhole PC pump design. A second part demonstrates how the PC pump design flexibility can be deployed to address specific operational challenges through a synopsis of the design and field experience of two novel PC pump configurations. The first new configuration uses a modified rotor geometry with alternating sections of interference and clearance fits with a standard stator. Since the clearance sections of the stator do not experience contact and as a result normally no elastomer damage, the associated section of stator remains intact in most cases even after prolonged pumping under problematic operating conditions. After the initial interference sections of the stator have been damaged, an adjustment to the rotor position can be made to the non-damaged section of the stator by lifting the rod string a short distance at surface, thus restoring pumping operation without surfacing the pump. The second novel PC pump configuration employs a modified low eccentricity large cross-section rotor geometry. Potential benefits of this configuration are a strong rotor that is less prone to breaking when operating in highly directional wellbore segments; reduced eccentric pump movement that minimizes rod breaks and vibration above the pump; a rotor profile that when sanded-in pulls free easier at lower safer loads for flushing/coiling; and a wider seal line profile that makes the rotor less prone to severe damage and results in higher salvage rates for rechroming. Several different models of both novel pump configurations have been developed and run in the field to confirm benefits.
