Subsea mud pump with reduced pulsation

• US 6,102,673 A
• Filed: 03/25/1999
• Issued: 08/15/2000
• Est. Priority Date: 03/27/1998
• Status: Expired due to Term

• Current Assignee: Hydril USA Manufacturing LLC (GE Aerospace)
• Original Assignee: Hydril Company L P (General Electric Company)
• Inventors: Mott, deceased, Keith C., Pelata, Kenneth L., Colvin, Kenneth W.
• Primary Examiner(s): FREAY, CHARLES GRANT
• Assistant Examiner(s): Evora, Robert Z.
• Application Number:
  US09/276,406
• Time in Patent Office: 509 Days
• Field of Search: 417/390, 417/392, 417/395, 417/401, 417/505, 417/521, 417/533, 137/596.17, 251/129.07, 251/324, 251/282
• US Class Current: 417/392
• CPC Class Codes: E21B 21/001 specially adapted for underwater drilling dual gradient drilling E21B21/082
• CPC Class Codes: E21B 21/01 Arrangements for handling drilling fluids or cuttings outside the borehole, e.g. mud boxes
• CPC Class Codes: E21B 21/08 Controlling or monitoring pressure or flow of drilling fluid, e.g. automatic filling of boreholes, automatic control of bottom pressure valve arrangements therefor E21B21/10
• CPC Class Codes: E21B 21/085 Underbalanced techniques, i.e. where borehole fluid pressure is below formation pressure
• CPC Class Codes: E21B 33/085 Rotatable packing means, e.g. rotating blow-out preventers
• CPC Class Codes: F04B 19/003 free-piston type pumps
• CPC Class Codes: F04B 43/06 Pumps having fluid drive
• CPC Class Codes: Y10T 137/87217 Motor

Abstract

A positive-displacement pump includes multiple pumping elements, each pumping element having a pressure vessel with a first and a second chamber and a separating member disposed between the first and second chambers. The first chambers and the second chambers are hydraulically connected to receive and discharge fluid, wherein the separating members move within the pressure vessels in response to pressure differential between the first and second chambers. A valve assembly having suction and discharge valves communicates with the first chambers. The suction and discharge valves are operable to permit fluid to alternately flow into and out of the first chambers. A hydraulic drive alternately supplies hydraulic fluid to and withdraws hydraulic fluid from the second chambers such that the fluid discharged from the first chambers is free of pulsation.

Claims

1. A positive-displacement pump, comprising:

a plurality of pumping elements, each pumping element comprising a pressure vessel with a first and a second chamber and a separating member disposed between the first and second chambers, the first chambers and the second chambers being hydraulically connected to receive and discharge a working fluid and a driving fluid, respectively, wherein the separating member moves within the pressure vessel in response to pressure differential between the first and second chambers;

a valve assembly having suction and discharge valves in communication with the first chambers, the suction and discharge valves being operable to permit fluid to alternately flow into and out of the first chambers, each of the valves comprising an actuator adapted to selectively open and close the valve to fluid flow therethrough; and

a fluid drive for alternately supplying the driving fluid to and drawing the driving fluid from the second chambers such that the fluid discharged from the first chambers is substantially free of pulsation.

2. The pump of claim 1, wherein the separating member is a diaphragm.

3. The pump of claim 1, wherein the separating member is a piston.

4. The pump of claim 1, wherein the hydraulic drive comprises:

a variable-displacement pump for supplying hydraulic fluid to the second chambers;

a plurality of flow control valves for alternately communicating the first pump with the second chambers; and

a control module for controlling the discharge rate of the variable-displacement pump and operation of the flow control valves.

5. The pump of claim 4, further comprising an additional pump for boosting pressure of the fluid flowing into the first chambers such that a positive pressure differential required to fill the first chambers with fluid is maintained.

6. The pump of claim 4, further comprising an additional pump for boosting pressure of the fluid flowing out of the second chambers such that a positive pressure differential required to fill the first chambers with fluid is maintained.

7. The pump of claim 4, further comprising a position locator for monitoring the position of the separating members within the pressures vessels.

8. The pump of claim 7, wherein the position locator is a magnetostrictive linear displacement transducer.

9. The pump of claim 4, further comprising a pressure sensor for measuring a difference in pressure between the fluid flowing into the first chambers and the fluid flowing out of the variable-displacement pump.

10. The pump of claim 1, wherein the hydraulic drive comprises a variable-displacement, reversing-flow pump for alternately supplying hydraulic fluid to and withdrawing hydraulic fluid from the second chambers.

11. The pump of claim 1, wherein the pumping elements operate out of phase such that the fluid suction into the first chambers is substantially free of pulsation.

12. The pump of claim 1, further comprising a seal assembly disposed in the housing, the seal assembly having a bore for receiving a first portion of the plunger and a seal member for sealing against the first portion such that fluid communication between the ports is prevented.

13. The pump of claim 12, wherein a second portion of the plunger includes spaced ribs and fluid pressure is communicated between a space below the plunger and a space above the plunger through the spaced ribs, thereby equalizing the pressure in the housing.

14. The pump of claim 12, wherein the seal assembly includes a seat portion which provides a positive stop for the plunger.

15. The pump of claim 1 wherein each of the suction and discharge valves comprises

a housing having a bore, an inlet port, and an outlet port;

a plunger disposed in the bore and movable between a first position to prevent fluid communication between the ports and a second position to permit fluid communication between the ports; and

an actuator coupled to the plunger and adapted to move the plunger between the first and second positions.

16. A positive-displacement pump, comprising:

a plurality of pumping elements, each of the pumping elements comprising a pressure vessel having a first and a second chamber and a separating member disposed between the first and second chambers, the first chamber and the second chamber being hydraulically connected to receive and discharge a working fluid and a driving fluid, respectively, wherein the separating member moves within the pressure vessel in response to pressure differential between the first and second chambers;

a valve assembly having actuated suction and discharge valves each in communication with one of the first chambers, the suction and discharge valves being selectively operable to permit fluid to alternately flow into and out of the first chambers;

a variable-displacement pump for supplying the driving fluid to the second chambers;

a plurality of flow control valves for alternately communicating the variable-displacement pump with the second chambers; and

a control module for controlling the discharge rate of the variable-displacement pump and the positions of the flow control valves such that the fluid discharged from the first chambers is substantially free of pulsation.

17. The pump of claim 16, further comprising a position locator for monitoring the position of the separating members within the pressure vessels.

18. The pump of claim 17, wherein the control module generates signals for controlling the positions of the flow control valves in response to signals received from the position locator.

19. The pump of claim 18, wherein the position locator comprises a magnetostrictive linear displacement transducer.

20. The pump of claim 16, further comprising an additional pump for boosting pressure of the fluid flowing out of the second chambers such that a positive pressure differential required to fill the first chambers with the working fluid is maintained.

21. The pump of claim 16, further comprising a booster pump for increasing pressure of the fluid flowing out of the second chambers such that a positive pressure differential needed to fill the second chambers with the driving fluid is maintained.

22. The pump of claim 16, wherein the control module synchronizes communication between the variable displacement pump, flow control valves, and suction and discharge valves, and at least three pumping elements such that the fluid drawn into and discharged from the first chambers of the pumping elements is substantially free of pulsation.

23. The pump of claim 16, wherein the variable-displacement pump is pressure compensated.

24. The pump of claim 16 wherein each of the suction and discharge valves comprises

a housing having a bore, an inlet port, and an outlet port;

a plunger disposed in the bore and movable between a first position to prevent fluid communication between the ports and a second position to permit fluid communication between the ports; and

an actuator coupled to the plunger and adapted to move the plunger between the first and second positions.