Submersible Pump Assembly Inside Subsea Flow Line Jumper and Method of Operation

Abstract

A subsea pumping assembly includes a flow line jumper connected between a well fluid source and a subsea flow line. A submersible pump assembly having a motor and pump os located in the flow line jumper. The pump has an intake in fluid communication with well fluid flowing into the flow line jumper. A bypass valve within the flow line jumper is coupled to a discharge of the pump. The bypass valve has a tubular housing, a bypass port extending through a wall of the housing, and a valve element upstream from the bypass port. The valve element is movable from a bypass position to a flow through position in response to discharge pressure of the pump. A spring biases the valve element toward the bypass position.

Description

FIELD OF THE DISCLOSURE

This disclosure relates in general to an electrical submersible pump assembly mounted in a subsea flow line jumper having a diverter valve that diverts well fluid flowing into the jumper past the pump and into the discharge flow line in the event the pump is not operating.

BACKGROUND

Offshore hydrocarbon production wells may be located in water thousands of feet deep. Some wells have inadequate internal pressure to cause the well fluid to flow to the sea floor and from the sea floor to a floating production vessel at the surface. Though not extensively used yet, various proposals exist to install booster pumps at the sea floor to boost the pressure of the well fluid.

Flowline jumpers are commonly employed to connect various sea floor production units to each other. A flowline juniper is a pipe having connectors on its ends for connection to inlets and outlets of the production units. It is known to install a flowline jumper by lowering it from a vessel on a lift line and using a remote operated vehicle (ROY) to make up the connections. Flowline jumpers may have U-shaped expansion joints with the connectors on downward extending legs for stabbing into receptacles of the production units. Generally, a flowline jumper is simply a communication pipe and contains no additional features for enhancing production.

U.S. Pat. No. 7,565,932 discloses placing an electrical submersible pump (ESP) within the flow line jumper to boost the pressure of the well fluid flowing from a subsea production tree to a manifold. The '932 patent does not discuss what occurs when the ESP is shut down, for whatever reason.

SUMMARY

In this disclosure, a submersible pump assembly is mounted within a chamber of a flow line assembly between a well fluid source and subsea production equipment. The submersible pump assembly comprises a motor and a pump having an intake downstream from the motor and a discharge leading to the production equipment and sealed from the chamber. A bypass valve is mounted within the chamber to the discharge of the pump, the bypass valve having a bypass port. While the pump is not operating, the bypass port is open for flowing well fluid from the well fluid source into the chamber, past the pump, into the bypass port, and out the chamber to the production equipment. While the pump is operating, the bypass port is closed for flowing well fluid from the well fluid source into the chamber and into the intake of the pump, which discharges the well fluid. out of the chamber at an increased pressure into the production equipment.

Preferably, closing the bypass port occurs in response to the occurrence of discharge pressure of the pump greater than pressure within chamber exterior of the pump. Opening the bypass port occurs in response to a spring biasing the bypass port open. Thus, in the preferred embodiment, opening and closing the bypass port is a function of discharge pressure of the pump.

Preferably, while the pump is not operating, a check valve prevents reverse flow through the bypass port into the chamber. A check valve is particularly used with first and second of the flow line assemblies, each having one of the chambers containing one of the submersible pump assemblies and one of the bypass valves. The discharges of the pumps are parallel. While the pump of the first flow line assembly is operating and the pump of the second flow line assembly is not, the check valve of the second flow line assembly blocks reverse flow of well fluid through the bypass port into the chamber of the second flow line assembly.

Normally, the chamber containing the submersible well pump assembly is oriented horizontally. The chamber is typically part of a flow line jumper between a subsea tree and a manifold.

The bypass valve isolates the discharge. of the pump from the bypass port while the bypass port is open. The isolation avoids any back flow through the pump While the bypass valve is in the bypass position.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic side view of a subsea flow line jumper containing an electrical submersible pump assembly in accordance with this disclosure.

FIG. 2 is a sectional view of a bypass valve employed with the pump assembly of FIG. 1, and shown in a bypass position while the pump is not pumping well fluid.

FIG. 3 is a sectional view of the bypass valve of FIG. 2, shown in a flow through position while the pump is pumping well fluid.

FIG. 4 is a schematic side view of the pump assembly of FIG. 1, shown while the pump is not pumping well fluid and the bypass valve in the bypass position.

FIG. 5 is a schematic side view of the pump assembly of FIG. 1, shown while the pump is pumping well fluid and the bypass valve is in the flow through position.

FIG. 6 is a top view of two flow line junipers, each having a check valve and containing a submersible pump assembly as shown in FIG. 1.

DETAILED DESCRIPTION OF THE DISCLOSURE

Referring to FIG. 1, a subsea production tree 11 is schematically illustrated. Tree 11 is a production unit located at the upper end of a well and has pressure control equipment for controlling the well fluid flow from the well. Tree 11 has a production well fluid outlet 13 that may be upward facing, as shown, or horizontal. Tree 11 is a well fluid source for flowing well fluid to other subsea production equipment, such as a manifold 15. Manifold 15 has an inlet 17, which also may be upward-facing or horizontal. Manifold 15 has an outlet 25 for flowing well fluid that it receives to a flow line, which in turn may lead to well fluid processing equipment at the sea surface. More than one production tree 11 may supply well fluid to manifold 15, as disclosed in FIG. 6.

A flow line jumper 27 connects tree ii to manifold 15. Flow line jumper 27 has a length sized for the spacing between tree 11 and manifold 15. Flow line jumper 27 has an upstream end or inlet 29 and a downstream end or outlet 31. Connectors 33 connect jumper inlet 29 to tree outlet 13 and jumper outlet 31 to manifold inlet 17. Jumper inlet 29 and outlet 31 are illustrated to have legs that thee downward for connection to the upward facing tree outlet 13 and manifold inlet 17; however, they could be oriented horizontally.

Flow line jumper 27 includes an elongated horizontal chamber 25 that contains an electrical submersible pump (ESP) 37. ESP 37 boosts the pressure of the well fluid flowing from tree 11 and delivers the fluid at an elevated pressure to manifold 15. ESP 37 has an electrical motor 39 that is typically a three-phase AC motor. Motor 39 is filled with a dielectric lubricant for lubricating and cooling. A seal section 41 connects to motor 39 for sealing the lubricant within motor 39 and reducing a pressure difference between well fluid pressure in chamber 35 and the lubricant pressure. An optional gas separator (not shown) may be connected to the end of seal section 41 opposite motor 39.

A rotary pump 43 driven by motor 39 connects to seal section 41. Pump 43 may be a centrifugal pump having a large number of stages, each stage having an impeller and diffuser. Alternately, pump 43 may be another type, such as a progressing cavity pump, which has a helical rotor that rotates inside a helical bore of an elastomeric stator. Pump 43 has an intake 45 that is in fluid communication with well fluid flowing into chamber 35 from tree 11. Pump 43 has a discharge 47 that is isolated from the well fluid pressure within chamber 35 on the exterior of ESP 37.

A bypass valve 49 connects pump discharge 47 sealingly to a downstream bulkhead 51 of chamber 35. Well fluid flowing through bypass valve 49 flows through bulkhead 51 and out jumper outlet 31. Bypass valve 49 has one or more bypass ports 53 that when open are in fluid communication with the well fluid flowing into chamber 35 from tree 11. When closed, bypass ports 53 isolate the well fluid flowing out of pump discharge 47 from the well fluid within chamber 35 on the exterior of ESP 37.

Referring to FIG. 4, an electrical motor lead 55 extends alongside ESP 37 within chamber 35 to motor 39 for supplying power. Motor lead 55 may extend sealingly through bulkhead Si to a source of power.

As illustrated in FIG. 4, bypass valve 49 has a bypass position that causes well fluid flowing into chamber 35 from jumper inlet 29 to flow past ESP 37, into bypass ports 53 and out jumper outlet 31. The bypass position occurs when ESP 37 is not pumping well fluid, such as when shut down or when a large gas bubble in the incoming well fluid may have gas locked ESP 37. In the bypass position, the well fluid does not flow into pump intake 45.

As illustrated in FIG. 5, bypass valve 49 has a flow through position that closes bypass ports 53 and directs the well fluid from chamber 35 to flow into pump intake 45. Pump 43 will be operating, thus will increase the pressure of the incoming well fluid and discharge the well fluid at higher pressure through bypass valve 49 into jumper outlet 31.

Bypass valve 49 may have a variety of components and configurations. Referring to FIGS. 2 and 3, in this example, bypass valve 49 has a tubular body 57 with a passage 59 extending through it along an axis 61. A valve element 63 within passage 59 moves between a bypass position opening bypass ports 53, as shown in FIG. 2, and a flow through position closing bypass ports 53, as shown in FIG. 3. Valve element 63 is a tubular member having a closed upstream end 65 that sealingly engages a seal surface 67 in passage 59 while in the bypass position. Seal surface 67 may be a shoulder within passage 59. Valve element 63 has one or more apertures or windows 69 in its side wall downstream from upstream end 65. The downstream end of valve element 63 is open.

While in the flow through position shown in FIG. 3, well fluid flows around upstream end 65 and through windows 69 into the interior of valve element 63, then out the open downstream end. The length of valve element 63 is selected to close off bypass ports 53 while valve element 63 is in the flow through position of FIG. 3. When valve element 63 is in the bypass position shown in FIG. 2, valve element 63 is entirely upstream from bypass ports 53, opening them. A coil swing 71 encircles valve element 63 and urges it upstream to the bypass position. Bypass ports 53 may be inclined relative to axis 61 in a downstream direction to facilitate the flow of well fluid into bypass ports 53 while they are open.

In operation, well fluid flows from tree 11 into chamber 35 at a positive pressure. While pump 43 is operating, the well fluid flows past motor 39 into pump intake 45. Pump 43 increases the pressure of the well fluid relative to the pressure at jumper inlet 29. At pump discharge 47, the elevated pressure acts against valve element 63, compressing spring 71 and pushing upstream end 65 away from its seated position, sealing against seal surface 67. As shown by the arrows in FIG. 3, the discharged well fluid flows through valve element windows 69 and out bypass valve 49 into jumper outlet 31. The movement of valve element 63 to the flow through position also doses bypass ports 53. During normal operation, the discharge pressure of pump 43 is sufficiently greater than the intake pressure, which is the pressure within chamber 35 exterior of ESP 37, to overcome the force of spring 71.

If the discharge pressure of pump 43 drops sufficiently relative to the pressure within chamber 35 exterior of pump 43, coil spring 71 forces valve element 63 back to the bypass position of FIG. 2. In the bypass position, bypass ports 53 are open. The sealing engagement of valve element upstream end 65 with seal surface 67 isolates pump discharge 47 from the pressure of well fluid flowing into bypass ports 53. Consequently, no portion of the well fluid flowing into bypass ports 53 will back flow into pump 43. Well fluid flowing into jumper inlet 29 thus flows past ESP 37 into bypass ports 53 and out jumper outlet 31.

The discharge pressure of pump 43 would drop to the same as the pressure at pump intake 45 if motor 39 is tamed off for whatever reason. Also, the discharge pressure of pump 43 may drop substantially to the pressure at pump intake 45 in the event the incoming well fluid contains a large gas bubble, causing pump 43 to gas lock. In either event, the well fluid flowing into jumper inlet 2.9 continues to flow through jumper 27 and to manifold 15. If a gas lock occurs, bypassing ESP 37 with the flowing well fluid allows ESP 37 to restart, possibly with no damage or at least less damage to ESP 37 than otherwise. A separate bypass line on the exterior of jumper 27, along with valves and control equipment, is not required. The bypass of ESP 37 occurs automatically in response to the discharge pressure of pump 43.

In FIG. 6, two trees 73, 75 supply well fluid separately to flow line jumpers 77, 79, respectively. The outlets of jumpers 77, 79 are in parallel with each other and connect to a manifold 81. Each jumper 77, 79 contains an ESP 83 having a bypass valve 85, as discussed in connection with FIGS. 1-5. Each bypass valve 85 has bypass ports 87. In this embodiment, a check valve 89 is mounted to each jumper outlet 91. Check valves 89 allows well fluid to flow from trees 73, 75 to manifold 81, but prevent any reverse flow from either jumper outlet 91 into either chamber 93. Check valves 89 could he mounted within chambers 93, but must be downstream of bypass ports 87. Check valves 89 thus prevent any reverse flow through bypass ports 87.

In the event the ESP 83 in one of the jumpers, for example jumper 77, is not operating while the other s operating, the bypass valve 85 in jumper 79 would be in the flow through position of FIG. 3. The bypass valve 85 in jumper 77 would be in the bypass position of FIG. 2, Since the outlets 91 of jumpers 77, 79 are in parallel, the higher pressure from the operating ESP 83 in jumper 79 would be present at the check valve 89 of jumper 77, which contains the non. operating ESP 83. The check valve 89 at jumper 77 would block reverse flow from jumper outlet 91 out the bypass ports 87 into the chamber 3 of jumper 77.

While the disclosure has been shown in only two of its forms, it should be apparent to those skilled in the art that it is not so limited but is susceptible to various changes without departing from the scope of the disclosure.

Claims

1. A method for boosting well fluid pressure of well fluid flowing from a subsea well fluid source through a subsea flow line assembly to production equipment, comprising:

mounting a submersible pump assembly within a chamber of the flow line assembly, the submersible pump assembly comprising a motor and a pump having an intake downstream from the motor and a discharge leading to the production equipment and sealed from the chamber;

mounting a bypass valve within the chamber and to the discharge of the pump, the bypass valve having a bypass port;

while the pump is not operating, opening the bypass port and flowing well fluid from the well fluid source into the chamber past the pump, into the bypass port, and out the chamber to the production equipment; and

while the pump is operating, closing the bypass port and flowing well fluid from the well fluid source into the chamber and into the intake of the pump, and discharging the well fluid out of the chamber through the discharge of the pump at an increased pressure into the production equipment.

2. The method according to claim 1, wherein closing the bypass port occurs in response to response to the occurrence of discharge pressure of the pump greater than pressure within chamber exterior of the pump.

3. The method according to claim 1, wherein opening the bypass port occurs in response to a spring biasing the bypass port open.

4. The method according to claim 1, wherein opening and closing the bypass port is a function of discharge pressure of the pump.

5. The method according to claim 1, further comprising while the pump is not operating, preventing reverse flow through the bypass port into the chamber.

6. The method according to claim 1, further comprising:

providing first and second of the flow line assemblies, each having one of the chambers containing one of the submersible pump assemblies and one of the bypass valves;

connecting the discharges of the pumps in parallel;

mounting a check valve downstream of the bypass port of each of the bypass valves; and

while the pump of the first flow line assembly is operating and the pump of the second flow line assembly is not, blocking reverse flow of well fluid through the bypass port into the chamber of the second flow line assembly.

7. The method according to claim 1, wherein mounting the submersible well pump assembly in the chamber comprises orienting the chamber horizontally.

8. The method according to claim 1, further comprising:

isolating the discharge of the pump from the bypass port while the bypass port is open.

9. An apparatus for boosting well fluid pressure of well fluid flowing from a subsea well fluid source through a subsea flow line assembly to a production equipment, comprising:

a submersible pump assembly mounted within a chamber of the flow line assembly, the submersible pump assembly comprising a motor and a pump having an intake downstream from the motor and a discharge sealed from the chamber;

a bypass valve within the chamber at the discharge of the pump, the bypass valve having a bypass port;

the bypass valve having an open position that occurs while the pump is not operating that opens the bypass port, enabling a flow of well fluid from the well fluid source into the chamber, past the pump, into the bypass port, and out the chamber to the production equipment; and

the bypass valve having a closed position that occurs while the pump is operating, closing the bypass port, enabling flowing of well fluid from the well fluid source into the chamber and into the intake of the pump for discharging the well fluid out of the chamber through the discharge of the pump at an increased pressure.

10. The apparatus according to claim 9, wherein the closed position of the bypass valve occurs in response to the discharge pressure of the pump being greater than pressure of the well fluid within the chamber.

11. The apparatus according to claim 9, wherein the bypass valve is biased to the open position.

12. The apparatus according to claim 9, further comprising:

a check valve mounted downstream of the bypass port and configured to prevent any reverse flow through the bypass port into the chamber.

13. The apparatus according to claim 9, wherein the bypass valve is configured such that during the closed position, the discharge of the pump is isolated from the bypass port.

14. A subsea pumping apparatus, comprising:

at least one flow line jumper having an upstream end for connection to a well fluid source of flowing well fluid and a downstream end for connection to subsea flow line;

a submersible pump assembly comprising a motor and a pump located in the flow line jumper, the pump having an intake downstream from the motor and in fluid communication with well fluid flowing into the flow line jumper from the upstream end;

a bypass valve within the flow line jumper and coupled to a discharge of the pump, the bypass valve comprising:

a tubular housing;

a bypass port extending through a wall of the housing;

a valve element in the housing upstream from the bypass port, the valve element being movable from a bypass position to a flow through position; wherein

the bypass position allows flow from the well fluid source through the flow line jumper around the pump into the bypass port and out the discharge; and

the flow through position blocks the bypass port and allows flow from the pump out the downstream end of the flow line jumper.

15. The apparatus according to claim 14, wherein the bypass valve element moves from the bypass position to the flow through position in response to discharge pressure of the pump being greater than well fluid pressure in the jumper exterior of the pump.

16. The apparatus according to claim 14, wherein the bypass valve element moves to the bypass position in response to cessation of pump discharge pressure.

17. The apparatus according to claim 14, further comprising a check valve downstream from the bypass port that prevents reverse flow from the downstream end of the flow line jumper out the bypass port and into the flow line jumper.

18. The apparatus according to claim 14, wherein:

the at least one flow line jumper comprises a plurality of flow line jumpers, each of the flow line jumpers containing one of the submersible pump assemblies and one of the bypass valves;

the downstream ends of the flow line jumpers are connected in parallel; and wherein the apparatus further comprises:

a check valve downstream from the bypass port of each of the flow line jumpers configured to prevent reverse flow through each of the bypass ports into each of the flow line jumpers.

19. The apparatus according to claim 14, wherein the bypass valve further comprises a spring that urges the valve element toward the bypass position.

20. The apparatus according to claim 14, wherein the valve element closes a passage from the discharge of the pump while in the bypass position.