Subsea Electric Submersible Pump Module System And Method

Abstract

The present disclosure provides a simplified electric submersible pump (ESP) system for installation into a borehole, regardless of whether a caisson is formed in the borehole or whether an internal volume under a cap of a housing with the ESP is pressurized. A frame with associated ESP equipment can be mounted over the borehole. The ESP system can allow direct access to the ESP without having to lift the frame or a housing surrounding the ESP for maintenance and repair. A bypass provides flow during the period in which the ESP in non-operational.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

Not applicable.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO APPENDIX

Not applicable.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The disclosure generally relates to the production of hydrocarbons from subsea formations. More particularly, the disclosure relates to a subsea pumping system and method generally located on the seafloor.

2. Description of the Related Art

In producing hydrocarbons from subsea formations, a number of wells are typically drilled into the seafloor. A subsea pump is often necessary to provide additional pressure or lifting head to lift well production fluids from the well to the water or land surface for processing into the desired hydrocarbons. Historically, the pumps have been electric submersible pumps (ESPs) that are installed in a borehole with a caisson of steel or concrete lining. The ESPs have an electrical motor connected to a rotary pump and associated equipment, such as seal sections for equalizing hydrostatic fluid pressure, a pump intake section, and electrical and fluid connectors. The ESP intake receives the well production fluids and the ESP discharge is connected to a riser, pipe, or other conduit for providing the fluids to the surface. The caisson can be sealed so that the fluids are received into the caisson first, and then allowed to flow into the ESP intake. The sealed caisson may also provide for a release of gas components entrapped in the well production fluids prior to the ESP, so that the ESP is able to pump more liquid components.

ESPs require periodic maintenance and have to be disconnected and typically brought to the surface. The scheduled maintenance may need several months' lead time. Also, ESPs can malfunction and cause unplanned maintenance or replacement. In each case, the production from the well is reduced or stopped during this period and the motivation in the field is to reduce the downtime.

For example, US Publication No. 2011/0056699 provides for multiple ESPs installed as a module in a parallel flow path to discharge to a common manifold. The ESP module is installed in a sealed caisson with the well production flowing into the caisson and then into one or more of the ESP intakes. Each ESP can be selectively operated to provide an overall desired flow rate and lifting head. While this design provides backup capabilities if one ESP fails, the design still suffers from the need to shut down production from the well to open the sealed caisson and pull the ESP module for maintenance and repair.

As another example, U.S. Pat. No. 7,516,795 shows an almost horizontal pumping module installed above the seafloor. A stationary flow base is installed on the seafloor and connected with the well production hydrocarbons. A pumping module can be releasably connected with the flow base. The entire pumping module can be disconnected and pulled to the surface when maintenance and repairs are needed. The design allows for disconnection and replacement with a backup unit, while the original unit is non-operational. However, the weight of the entire pumping module may require lifting equipment that common service vessels may not have. The weight and size may require special rigging with added expense and additional lead times for scheduling.

US Publication No. 2010/0119382 also shows a horizontal installation of a pumping unit on a skid that can be lowered to the seafloor and installed on top of the seafloor. The pumping unit includes a horizontal outer housing which encloses an ESP system. Well production fluids enter the housing, encircled the pumping unit in the housing, flow into the pump intake, and then are pressurized through the pump discharge. The entire pumping unit with the housing and ESP system can be disconnected at a connector on each of the inlet and outlet of the housing. A bypass can be used while the pumping unit is non-operational. Depending on the weight and size of the pumping unit with the housing in addition to the ESP system, special rigging may be required.

U.S. Pat. No. 7,150,325 shows an ESP system in a primary housing installed in the seafloor. The primary housing communicates with an intake conduit for receiving well production fluids from an adjacent well. A capsule hanger is installed in the primary housing and extends downward to form a receptacle. A capsule lands on the capsule hanger and sealingly engages the primary housing intake and sealingly engages the downward receptacle. An ESP is mounted inside the capsule and has an intake open to an inner volume of the capsule. Well productions fluids enter through the primary housing intake, flow around the capsule hanger and the receptacle, into an inner volume of the capsule, into the ESP intake, and out through the capsule through an outlet in the head. For maintenance and repair, the well productions fluids are stopped, a cap on the primary housing is removed, and the capsule with the ESP therein can be retrieved. Thus, the retrieval of a combined housing with an ESP therein is similar to the combined housing with an ESP in the above US is Publication No. 2010/0119382.

Despite these designs, there remains then a need to simplify the structure of an ESP subsea installation that can allow ease of access, minimal time to schedule maintenance, and minimal downtime of production.

BRIEF SUMMARY OF THE INVENTION

The present disclosure provides a simplified electric submersible pump (ESP) system for installation into a borehole, regardless of whether a caisson is formed in the borehole or whether an internal volume under a cap of a housing with the ESP is pressurized. A frame with associated ESP equipment can be mounted over the borehole. The ESP system can allow direct access to the ESP without having to lift the frame or a housing surrounding the ESP for maintenance and repair. A bypass provides flow during the period in which the ESP in non-operational.

The disclosure provides a system for pumping fluids from a subsea location, comprising: an inlet conduit; a bypass valve coupled to the inlet conduit; a bypass conduit coupled to the bypass valve; an electric submersible pump (ESP) flow circuit coupled to the bypass conduit; and an outlet conduit coupled to the receiver outlet of the ESP flow circuit and to the bypass conduit. The ESP flow circuit coupled to the bypass conduit, comprises an ESP valve; a vertically disposed ESP conduit loop coupled to the ESP valve and configured to fit into a vertical borehole formed in a seafloor; an ESP housing coupled to the ESP conduit loop, comprising an ESP receiver having a receiver outlet and a removable cap; a vertically disposed ESP hanger coupled in an interior volume of the ESP receiver and supported by the ESP receiver, the ESP hanger having an internal bore fluidicly coupled to the receiver outlet; and a vertically disposed ESP coupled to the ESP hanger, the ESP having an inlet within the ESP conduit loop and an outlet coupled to the internal bore of the ESP hanger; wherein flow through the ESP conduit loop and the ESP housing is independent of any flow in the borehole formed in the seafloor, and wherein the receiver is configured to allow removal of the ESP hanger with an exposed ESP independent of a removal of the ESP receiver and to allow direct access to the ESP.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is an elevational front schematic view of an exemplary system for pumping fluids from a subsea location according to the present invention.

FIG. 2 is a side schematic view of the embodiment of FIG. 1.

FIG. 3 is a top schematic view of the embodiment of FIG. 1.

FIG. 4 is a schematic cross sectional view of an ESP housing containing an ESP.

FIG. 5 is a schematic cross section view of an electrical through the ESP housing.

DETAILED DESCRIPTION

The Figures described above and the written description of specific structures and functions below are not presented to limit the scope of what Applicant has invented or the scope of the appended claims. Rather, the Figures and written description are provided to teach any person skilled in the art to make and use the inventions for which patent protection is sought. Those skilled in the art will appreciate that not all features of a commercial embodiment of the inventions are described or shown for the sake of clarity and understanding. Persons of skill in this art will also appreciate that the development of an actual commercial embodiment incorporating aspects of the present disclosure will require numerous implementation-specific decisions to achieve the developer's ultimate goal for the commercial embodiment. Such implementation-specific decisions may include, and likely are not limited to, compliance with system-related, business-related, government-related and other constraints, which may vary by specific implementation, location and from time to time. While a developer's efforts might be complex and time-consuming in an absolute sense, such efforts would be, nevertheless, a routine undertaking for those of ordinary skill in this art having benefit of this disclosure. It must be understood that the inventions disclosed and taught herein are susceptible to numerous and various modifications and alternative forms. The use of a singular term, such as, but not limited to, “a,” is not intended as limiting of the number of items. Also, the use of relational terms, such as, but not limited to, “top,” “bottom,” “left,” “right,” “upper,” “lower,” “down,” “up,” “side,” and the like are used in the written description for clarity in specific reference to the Figures and are not intended to limit the scope of the invention or the appended claims. Where appropriate, one or more elements may have been labeled with an “A” or “B” to designate various members of a given class of an element. When referring generally to such elements, the number without the letter is used. Further, such designations do not limit the number of members that can be used for that function.

The present disclosure provides a simplified electric submersible pump (ESP) system for installation into a borehole, regardless of whether a caisson is formed in the borehole or whether an internal volume under a cap of a housing with the ESP is pressurized. A frame with associated ESP equipment can be mounted over the borehole. The ESP system can allow direct access to the ESP without having to lift the frame or a housing surrounding the ESP for maintenance and repair. A bypass provides flow during the period in which the ESP in non-operational.

FIG. 1 is an elevational front schematic view of an exemplary system for pumping fluids from a subsea location according to the present invention. FIG. 2 is a side schematic view of the embodiment of FIG. 1. FIG. 3 is a top schematic view of the embodiment of FIG. 1. FIG. 4 is a schematic cross sectional view of an ESP housing containing an ESP.

FIG. 5 is a schematic cross section view of an electrical through the ESP housing. The Figures will be described in conjunction with each other. The exemplary system 2 for pumping fluids from a subsea location includes an assembly of pipe, tubing, and other conduits and various equipment mounted on a frame 10. A portion of the system is disposed downward into a borehole 4 formed in a seafloor 3. The borehole optionally can be cased with a caisson 6, but the operation of the ESP system is independent of a caisson or a pressurized volume in the caisson. The frame 10 can be mounted on a support structure 8 that is mounted to the caisson 6.

Starting on the left of FIG. 1, an inlet 16 can be fluidicly coupled to one or more wells (not shown) from which well production fluids flow into the inlet. The inlet 16 can be supported by an inlet support 12 of various structural members. The inlet 16 can be coupled to an inlet conduit 18 forming an inlet flow circuit that can be divided into a bypass flow circuit 22 and an ESP flow circuit 32. The bypass circuit 22 includes conduits, clamps, valves and other equipment, including a bypass valve 23 disposed therein to control flow through the bypass flow circuit. The bypass circuit 23 can rejoin the ESP flow circuit 32 on a downstream portion of the bypass flow circuit and ESP flow circuit after the ESP 52 described below. After the bypass circuit 22 rejoins the ESP flow circuit 32 and is coupled with an outlet conduit 26, the outlet conduit can form an outlet flow circuit and be coupled to an outlet 30 of the system 2. The outlet 30 and associated conduit 26 can be supported by an outlet support 28 of various structural members. The outlet 30 can be coupled up to a riser, piping, or other conduit (not shown) that can be used to flow the well production fluids to the surface for further processing.

The ESP flow circuit 32 includes at least one valve 20 that can isolate the ESP flow is circuit 32 from flow through the bypass circuit 22. The valve 20 can be disposed in close proximity to the bypass flow circuit 22. The valve 20 can be coupled to an ESP inlet conduit 34 that can join an ESP conduit loop 38. In some embodiments, an additional valve 36 can be coupled to the ESP inlet conduit as an additional valve to control the fluid therethrough. The conduit loop 38 is generally shaped into a loop that can extend downward into the borehole 4. If a caisson 6 is installed in the borehole, then the loop can extend downward into the caisson as well. The length of the loop can vary and, as an example but without limitation, could be about 30 meters to 40 meters long. The loop can form a U-turn and come back up toward the assembly of valves and conduits on the frame 10. At least one of the downwardly disposed conduits of the ESP conduit loop can have a sufficient inside diameter and length into which the ESP 52 can be inserted vertically.

An ESP housing 40 can form a portion of the ESP conduit loop 38. The ESP housing 40 includes an ESP receiver 42 that receives an assembly to which the ESP 52 is coupled, as explained below. The ESP receiver 42 generally includes a cap 44 to restrict debris and the like from entering an internal volume 43 of the receiver. The design of the system 2 does not depend upon the pressurized internal volume 53 in contrast to earlier designs. Thus, the cap 44 can be opened without requiring time for depressurization of an internal volume of earlier pressurized designs. The ESP receiver 42 includes a receiver outlet 46 through which production fluids from the discharge of the ESP 52 can be pumped. The ESP receiver 42 also includes a hanger shoulder 48, which can be a tapered surface extending inwardly toward the internal volume 43 of the ESP receiver 42. An ESP hanger 50 is coupled with the ESP 52 in some embodiments through an intermediate conduit 54. The ESP hanger 50 includes a bore 56 therethrough that is fluidicly coupled to the conduit 54 and the discharge of the ESP 52 on a first portion. On a second portion of the ESP hanger 50 that is distal from the first portion, a hanger outlet 60 intersects the bore 56 and is fluidicly coupled with the receiver outlet 46. Thus, the well production fluid enters into an intake of the ESP 52, and is discharged through the conduit 54, through the bore 56, laterally outward through the hanger outlet 60, through the receiver outlet 46, and thence on to other portions of the ESP flow circuit 32. The ESP hanger 50 can sealingly engage the internal surfaces of the ESP receiver 42 through seals 62 and 64. Thus, the sealingly engaged ESP hanger 50 restricts pressure of the well production fluids below the hanger from entering the internal volume 43 above the hanger, so that the cap 44 is not under a pressurized embodiment from internal pressure.

Electrical service to the ESP 52 can be supplied through an electrical cable 74 from the is ESP 52 through the ESP hanger 50 and laterally outward through the ESP receiver 42. An electrical connector 76 can be coupled to the electrical cable 74. The electrical connector 76 can be used to detachably couple electrical service to the electrical cable 74, so that the ESP hanger 50 can be removed from the ESP receiver 42.

Once the well production fluids have been pumped through the ESP 52 and discharged through the ESP receiver 42, the fluid can reenter the conduit of the ESP flow circuit 32 external to the ESP housing 40. A valve 66 coupled in the ESP flow circuit 32 can be used to control the flow on the ESP flow circuit downstream from the ESP housing 40. The valve 66 can further be coupled to an ESP outlet conduit 72, which can be coupled to another valve 24. The ESP flow circuit 32 can rejoin the bypass flow circuit 22 and well production fluids can then flow into the outlet conduit 26 that is described above.

The design and circuitry of the flow paths can vary. In some embodiments, a bypass circuit may not be used. In other embodiments, the extra set of valves on the inlet and outlet to the ESP conduit loop 38 may not be used. In some embodiments, a caisson may be used and in other embodiments, an open frame structure can be used to protect the ESP conduit loop. In some embodiments, the frame 10 can be mounted to the seafloor. Other and further embodiments utilizing one or more aspects of the inventions described above can be devised without departing from the spirit of the disclosed invention.

Further, the various methods and embodiments of the system can be included in combination with each other to produce variations of the disclosed methods and embodiments. Discussion of singular elements can include plural elements and vice-versa. References to at least one item followed by a reference to the item may include one or more items. Also, various aspects of the embodiments could be used in conjunction with each other to accomplish the understood goals of the disclosure. Unless the context requires otherwise, the word “comprise” or variations such as “comprises” or “comprising,” should be understood to imply the inclusion of at least the stated element or step or group of elements or steps or equivalents thereof, and not the exclusion of a greater numerical quantity or any other element or step or group of elements or steps or equivalents thereof. The device or system may be used in a number of directions and orientations. The term “coupled,” “coupling,” “coupler,” and like terms are used broadly herein and may include any method or device for securing, binding, bonding, fastening, attaching, joining, inserting therein, forming thereon or therein, communicating, or otherwise associating, for example, mechanically, magnetically, electrically, is chemically, operably, directly or indirectly with intermediate elements, one or more pieces of members together and may further include without limitation integrally forming one functional member with another in a unity fashion. The coupling may occur in any direction, including rotationally.

The order of steps can occur in a variety of sequences unless otherwise specifically limited. The various steps described herein can be combined with other steps, interlineated with the stated steps, and/or split into multiple steps. Similarly, elements have been described functionally and can be embodied as separate components or can be combined into components having multiple functions.

The invention has been described in the context of preferred and other embodiments and not every embodiment of the invention has been described. Obvious modifications and alterations to the described embodiments are available to those of ordinary skill in the art. The disclosed and undisclosed embodiments are not intended to limit or restrict the scope or applicability of the invention conceived of by the Applicant, but rather, in conformity with the patent laws, Applicant intends to protect fully all such modifications and improvements that come within the scope or range of equivalent of the following claims.

Claims

1. A system for pumping fluids from a subsea location, comprising:

an inlet conduit;

a bypass valve coupled to the inlet conduit;

a bypass conduit coupled to the bypass valve;

an electric submersible pump (ESP) flow circuit coupled to the bypass conduit, comprising: an ESP valve; a vertically disposed ESP conduit loop coupled to the ESP valve and configured to fit into a vertical borehole formed in a seafloor; an ESP housing coupled to the ESP conduit loop, comprising an ESP receiver having a receiver outlet and a removable cap; a vertically disposed ESP hanger coupled in an interior volume of the ESP receiver and supported by the ESP receiver, the ESP hanger having an is internal bore fluidicly coupled to the receiver outlet; and a vertically disposed ESP coupled to the ESP hanger, the ESP having an inlet within the ESP conduit loop and an outlet coupled to the internal bore of the ESP hanger; wherein flow through the ESP conduit loop and the ESP housing is independent of any flow in the borehole formed in the seafloor, and wherein the receiver is configured to allow removal of the ESP hanger with an exposed ESP independent of a removal of the ESP receiver and to allow direct access to the ESP; and

an outlet conduit coupled to the receiver outlet of the ESP flow circuit and to the bypass conduit.

2. The system of claim 1, wherein a flow of fluids into the pump inlet is independent of flow of other fluids in the borehole.

3. The system of claim 1, wherein flow of the fluids into the ESP intake is exclusive of flow in the borehole.

4. The system of claim 1, wherein the borehole comprises nonpressurized borehole.

5. The system of claim 1, wherein the ESP comprises a pump that is oriented inline with flow through the ESP conduit loop.

6. The system of claim 1, further comprising a bypass conduit coupled to an inlet of the ESP conduit loop on one portion and an outlet of the ESP conduit loop on a second portion.

7. The system of claim 6, further comprising a valve disposed in the bypass conduit and configured to close to restrict flow through the bypass conduit.

8. The system of claim 7, further comprising a valve disposed in the ESP conduit loop and configured to close to restrict flow through the ESP conduit loop.

9. The system of claim 1, further comprising a detachable electrical connection coupled through the receiver to the ESP.

10. The system of claim 1, wherein the ESP receiver comprises a zone above the ESP hanger and wherein the zone is non-pressurized during flow through the ESP hanger.

11. The system of claim 1, further comprising a caisson at least partially surrounding the ESP conduit loop