Patent ID: 6505691
Filing Date: 2003-01-14
Classification: E21B,F04B,Y10T

Abstract:
A subsea pump comprising:a plurality of pumping elements, each pumping element comprising a pressure vessel with a first and a second chamber therein and a separating member disposed between the first and second chambers, the first and second chambers being hydraulically coupled to receive and discharge a hydraulic fluid and a drilling fluid, respectively, wherein the separating member moves within the pressure vessel in response to a pressure differential between the first and second chambers; a hydraulic power supply adapted to pump the hydraulic fluid to the first chamber of each of the pumping elements; a valve assembly hydraulically coupled to the first chambers of the plurality of pumping elements and to the hydraulic power supply; volume measurement devices adapted to measure volumes of each of at least one of the first and second chambers; and a valve controller operatively coupled to the valve assembly and to the volume measurement devices, the valve controller adapted to control a rate and timing of application of the hydraulic fluid to each of the first chambers and a timing of discharge of hydraulic fluid therefrom in response to the measurements of volume so as to maintain at least one of a substantially constant pump inlet pressure, a substantially constant pump discharge pressure, and a substantially constant total volume of the first chambers.