Subsea multiphase pumping systems

1. A multiphase pumping system for subsea operation, said system comprising:

a pump;

a flow inlet for accepting incoming multiphase flow and directing incoming multiphase flow generally towards said pump;

a flow outlet for directing outgoing multiphase flow generally away from said pump;

a flow management apparatus in fluid communication with said pump and at least one of said flow inlet and said flow outlet;

said flow management apparatus configured to ensure a minimum liquid content in multiphase flow entering said pump;

said flow management apparatus comprising:

a gas liquid cylindrical cyclone in communication with said flow outlet;

a recirculation port disposed in said gas liquid cylindrical cyclone; and

a recirculation line in communication with said recirculation port, said recirculation line configured to direct flow generally towards said pump;

said gas liquid cylindrical cyclone comprising a cyclonic column, a recombination column and at least one conduit interconnecting said cyclonic column and said recombination column; and

said recombination column having an average diameter sufficient for preserving liquid flow velocity to maintain particulates within liquid flow in suspension.

2. The system according to claim 1 , wherein said recombination column has an average diameter greater than or equal to an average diameter of said cyclonic column.

3. A multiphase pumping system for subsea operation, said system comprising:

a pump;

a flow inlet for accepting incoming multiphase flow and directing incoming multiphase flow generally towards said pump;

a flow outlet for directing outgoing multiphase flow generally away from said pump;

a flow management apparatus in fluid communication with said pump and at least one of said flow inlet and said flow outlet;

said flow management apparatus configured to ensure a minimum liquid content in multiphase flow entering said pump;

said flow management apparatus comprising:

a gas liquid cylindrical cyclone in communication with said flow outlet;

a recirculation port disposed in said gas liquid cylindrical cyclone; and

a recirculation line in communication with said recirculation port, said recirculation line configured to direct flow generally towards said pump;

said flow management apparatus further comprising an impeding device configured to impede at least a portion of liquid flow in advance of said recirculation port.

4. The system according to claim 3 , wherein said impeding device is configured to maintain liquid in said gas liquid cylindrical cyclone sufficient for ensuring a minimum liquid content in multiphase flow entering said pump.

5. The system according to claim 4 , wherein:

said gas liquid cylindrical cyclone comprises a cyclonic column, a recombination column and at least one conduit interconnecting said cyclonic column and said recombination column;

said impeding device and said recirculation port being disposed in said recombination column.

6. The system according to claim 5 , wherein said recombination column has an average diameter sufficient for preserving liquid flow velocity to maintain particulates within liquid flow in suspension.

7. The system according to claim 6 , wherein said recombination column has an average diameter greater than or equal to an average diameter of said cyclonic column.

8. The system according to claim 5 , wherein:

said at least one conduit comprises a conduit interconnecting said cyclonic column and said recombination column at a lower portion of said cyclonic column and said recombination column;

said impeding device is interposed between said conduit and said recirculation port.

9. The system according to claim 8 , wherein said recirculation port is disposed at a lowermost portion of said recombination column.

10. The system according to claim 5 , wherein said impeding device comprises a baffle disposed at a lower portion of said recombination column.

11. The system according to claim 10 , wherein said baffle extends across a major portion of a diametric dimension of said recombination column.

12. The system according to claim 11 , wherein said baffle is shaped to permit limited liquid flow therepast below an uppermost portion of said baffle.

13. The system according to claim 12 , wherein said baffle comprises chamfered corners at a lowermost portion of said baffle.

14. The system according to claim 3 , further comprising an arrangement, in communication with said recirculation line, for providing heat exchange to ambient.

15. The system according to claim 14 , wherein said arrangement for affording heat exchange comprises a coiled intercooler.

16. The system according to claim 3 , further comprising an arrangement, in communication with said recirculation line, for limiting recirculation flow in advance of said pump.

17. The system according to claim 16 , wherein said arrangement for limiting recirculation flow comprises a choke valve.

18. The system according to claim 17 , wherein said arrangement for limiting recirculation flow further comprises a flow meter in communication with said choke valve.

19. The system according to claim 16 , wherein said arrangement for limiting recirculation flow comprises a fast-acting shutoff valve.

20. The system according to claim 3 , wherein:

said gas liquid cylindrical cyclone comprises a cyclonic column, a recombination column and at least one conduit interconnecting said cyclonic column and said recombination column; and

said recombination column has an average diameter sufficient for preserving liquid flow velocity to maintain particulates within liquid flow in suspension.

21. The system according to claim 20 , wherein said recombination column has an average diameter greater than or equal to an average diameter of said cyclonic column.

22. A multiphase pumping system for subsea operation, said system comprising:

a pump;

a flow inlet for accepting incoming multiphase flow and directing incoming multiphase flow generally towards said pump;

a flow outlet for directing outgoing multiphase flow generally away from said pump;

a flow management apparatus in fluid communication with said pump and at least one of said flow inlet and said flow outlet;

said flow management apparatus configured to ensure a minimum liquid content in multiphase flow entering said pump;

said flow management apparatus comprising:

a gas liquid cylindrical cyclone in communication with said flow outlet;

a recirculation port disposed in said gas liquid cylindrical cyclone; and

a recirculation line in communication with said recirculation port, said recirculation line configured to direct flow generally towards said pump;

said gas liquid cylindrical cyclone comprising a recombination column; and

said recirculation port is being disposed at a lowermost portion of said recombination column.

23. The system according to claim 22 , wherein said pump comprises a twin-screw multiphase pump.

24. The system according to claim 22 , wherein:

said gas liquid cylindrical cyclone further comprises a cyclonic column and at least one conduit interconnecting said cyclonic column and said recombination column; and

said recombination column has an average diameter sufficient for preserving liquid flow velocity to maintain particulates within liquid flow in suspension.

25. The system according to claim 24 , wherein said recombination column has an average diameter greater than or equal to an average diameter of said cyclonic column.

26. The system according to claim 22 , wherein said flow management apparatus further comprises an impeding device configured to impede at least a portion of liquid flow in advance of said recirculation port.

27. The system according to claim 26 , wherein said impeding device is configured to maintain liquid in said gas liquid cylindrical cyclone sufficient for ensuring a minimum liquid content in multiphase flow entering said pump.

28. The system according to claim 26 , further comprising an arrangement, in communication with said recirculation line, for providing heat exchange to ambient.

29. The system according to claim 26 , further comprising an arrangement, in communication with said recirculation line, for limiting recirculation flow in advance of said pump.

30. A multiphase pumping system for subsea operation, said system comprising:

a pump;

a flow inlet for accepting incoming multiphase flow and directing incoming multiphase flow generally towards said pump;

a flow outlet for directing outgoing multiphase flow generally away from said pump;

a flow management apparatus in fluid communication with said pump and at least one of said flow inlet and said flow outlet;

said flow management apparatus configured to ensure a minimum liquid content in multiphase flow entering said pump;

said flow management apparatus comprising:

a gas liquid cylindrical cyclone in communication with said flow outlet;

a recirculation port disposed in said gas liquid cylindrical cyclone; and

a recirculation line in communication with said recirculation port, said recirculation line configured to direct flow generally towards said pump;

said flow management apparatus further comprising:

a liquid slug distributor;

said liquid slug distributor comprising an inlet and an outlet, said outlet being in communication with said pump;

said liquid slug distributor configured to regulate gas slugs incoming from said inlet in a manner to ensure propagation, through said outlet, of a minimum liquid content in multiphase flow.

31. The system according to claim 30 , wherein said inlet of said liquid slug distributor is in communication with said recirculation line.

32. A multiphase pumping system for subsea operation, said system comprising:

a pump;

a flow inlet for accepting incoming multiphase flow and directing incoming multiphase flow generally towards said pump;

a flow outlet for directing outgoing multiphase flow generally away from said pump;

a flow management apparatus in fluid communication with said pump and at least one of said flow inlet and said flow outlet;

said flow management apparatus configured to ensure a minimum liquid content in multiphase flow entering said pump;

said flow management apparatus comprising:

a liquid slug distributor;

said liquid slug distributor comprising an inlet and an outlet, said outlet being in communication with said pump;

said liquid slug distributor configured to regulate gas slugs incoming from said inlet in a manner to ensure propagation, through said outlet, of a minimum liquid content in multiphase flow,

said liquid slug distributor configured to limit the duration of predominantly gas slugs propagating into said outlet;

said liquid slug distributor further comprising a barrier dividing said interior chamber into upper and lower sub-chambers; and

said barrier comprising throughholes for admitting a predetermined liquid flow profile between said upper and lower sub-chambers.

33. The system according to claim 32 , wherein:

said liquid slug distributor comprises an interior chamber; and

said inlet is configured for creating a vortex within said interior chamber.

34. The system according to claim 33 , wherein said inlet comprises a tangential inlet.

35. The system according to claim 32 , wherein:

said liquid slug distributor comprises metering holes for admitting a predetermined liquid flow profile from said lower sub-chamber to said outlet; and

said throughholes are sized and disposed to break down paraffin in a manner to preclude blockage of said metering holes.

36. The system according to claim 35 , wherein:

said liquid slug distributor further comprises a standpipe extending through said barrier between said upper and lower sub-chambers;

said standpipe comprising an inlet disposed above said inlet of said liquid slug distributor and an outlet which directs flow into said outlet of said liquid slug distributor.

37. The system according to claim 36 , wherein said standpipe bypasses said metering holes in directing flow into said outlet of said liquid slug distributor.

38. The system according to claim 35 , further comprising at least one breather tube in communication with said upper and lower sub-chambers.

39. The system according to claim 38 , wherein said at least one breather tube extends from said barrier upwardly into said upper chamber.

40. The system according to claim 39 , further comprising a support web interconnecting said standpipe and said at least one breather tube at upper portions of said standpipe and said at least one breather tube.

41. The system according to claim 32 , wherein said pump comprises a twin-screw multiphase pump.

42. A gas liquid cylindrical cyclone for a multiphase pumping system for subsea operation, said gas liquid cylindrical cyclone comprising:

a recirculation port for communicating with a pump;

a cyclonic column;

a recombination column; and

at least one conduit interconnecting said cyclonic column and said recombination column;

said recombination column having an average diameter sufficient for preserving liquid flow velocity to maintain particulates within liquid flow in suspension.

43. The gas liquid cylindrical cyclone according to claim 42 , wherein said recombination column has an average diameter greater than or equal to an average diameter of said cyclonic column.

44. A gas liquid cylindrical cyclone for a multiphase pumping system for subsea operation, said gas liquid cylindrical cyclone comprising:

a recirculation port for communicating with a pump; and

an impeding device configured to impede at least a portion of liquid flow in advance of said recirculation port.

45. The gas liquid cylindrical cyclone according to claim 44 , wherein said impeding device is configured to maintain liquid in said gas liquid cylindrical cyclone sufficient for ensuring a minimum liquid content in multiphase flow entering a pump.

46. The gas liquid cylindrical cyclone according to claim 45 , wherein:

said gas liquid cylindrical cyclone comprises a cyclonic column, a recombination column and at least one conduit interconnecting said cyclonic column and said recombination column;

said impeding device and said recirculation port being disposed in said recombination column.

47. The gas liquid cylindrical cyclone according to claim 46 , wherein:

said at least one conduit comprises a conduit interconnecting said cyclonic column and said recombination column at a lower portion of said cyclonic column and said recombination column;

said impeding device is interposed between said conduit and said recirculation port.

48. The gas liquid cylindrical cyclone according to claim 44 , further comprising: a cyclonic column;

a recombination column; and

at least one conduit interconnecting said cyclonic column and said recombination column;

said recombination column having an average diameter sufficient for preserving liquid flow velocity to maintain particulates within liquid flow in suspension.

49. The gas liquid cylindrical cyclone according to claim 48 , wherein said recombination column has an average diameter greater than or equal to an average diameter of said cyclonic column.

50. A gas liquid cylindrical cyclone for a multiphase pumping system for subsea operation, said gas liquid cylindrical cyclone comprising:

a recirculation port for communicating with a pump;

said gas liquid cylindrical cyclone comprises a recombination column; and

said recirculation port is being disposed at a lowermost portion of said recombination column.

51. The gas liquid cylindrical cyclone according to claim 50 , further comprising: a cyclonic column;

at least one conduit interconnecting said cyclonic column and said recombination column;

said recombination column having an average diameter sufficient for preserving liquid flow velocity to maintain particulates within liquid flow in suspension.

52. The gas liquid cylindrical cyclone according to claim 51 , wherein said recombination column has an average diameter greater than or equal to an average diameter of said cyclonic column.

53. The gas liquid cylindrical cyclone according to claim 50 , further comprising an impeding device configured to impede at least a portion of liquid flow in advance of said recirculation port.

54. The gas liquid cylindrical cyclone according to claim 53 , wherein said impeding device is configured to maintain liquid in said gas liquid cylindrical cyclone sufficient for ensuring a minimum liquid content in multiphase flow entering a pump.

55. The gas liquid cylindrical cyclone according to claim 54 , wherein:

said gas liquid cylindrical cyclone further comprises a cyclonic column and at least one conduit interconnecting said cyclonic column and said recombination column;

said impeding device and said recirculation port being disposed in said recombination column.

56. The gas liquid cylindrical cyclone according to claim 55 , wherein:

said at least one conduit comprises a conduit interconnecting said cyclonic column and said recombination column at a lower portion of said cyclonic column and said recombination column;

said impeding device is interposed between said conduit and said recirculation port.

57. A liquid slug distributor for a multiphase pumping system for subsea operation, said liquid slug distributor comprising:

an inlet; and

an outlet for communicating with a pump;

said liquid slug distributor configured to regulate gas slugs incoming from said inlet in a manner to ensure propagation, through said outlet, of a minimum liquid content in multiphase flow;

said liquid slug distributor configured to limit the duration of predominantly gas slugs propagating into said outlet;

said liquid slug distributor comprising an interior chamber;

said liquid slug distributor further comprising a barrier dividing said interior chamber into upper and lower sub-chambers; and

said barrier comprising throughholes for admitting a predetermined liquid flow profile between said upper and lower sub-chambers.

58. The liquid slug distributor according to claim 57 , wherein:

said inlet is configured for creating a vortex within said interior chamber.

59. A method of providing multiphase pumping in subsea operation, said method comprising:

providing a pump;

accepting incoming multiphase flow and directing incoming multiphase flow generally towards the pump;

directing outgoing multiphase flow generally away from the pump;

ensuring a minimum liquid content in multiphase flow entering the pump;

said step of ensuring a minimum liquid content comprising:

providing a gas liquid cylindrical cyclone; and

recirculating at least a portion of liquid flow in the gas liquid cylindrical cyclone generally towards the pump;

step of ensuring a minimum liquid content further comprising:

providing a liquid slug distributor; and

regulating gas slugs incoming into the liquid slug distributor in a manner to ensure propagation of a minimum liquid content in multiphase flow exiting out of the liquid slug distributor.

60. The method according to claim 59 , wherein said recirculating step comprises recirculating at least a portion of liquid flow in the gas liquid cylindrical cyclone into the liquid slug distributor.

61. The method according to claim 60 , wherein said recirculating step comprises:

providing continuous recirculation flow via the gas liquid cylindrical cyclone during pump startup and until steady state multiphase flow through the pump is achieved; and

thereafter throttling recirculation flow from the gas liquid cylindrical cyclone.