1. Field of the Invention
Generally, the present disclosure relates to a system that may be employed in recovering hydrocarbons from oil and gas wells. More specifically, the present disclosure is directed to various embodiments of a system for operating a hydraulically-powered submersible pump that uses a pump positioned subsea to supply the pressurized fluid to drive the submersible pump.
2. Description of the Related Art
As the technology for offshore deep-water exploitation becomes available at a reasonable cost, the number of sub-sea completions in deep and ultra-deep waters is expected to increase significantly. Today, high productivity wells have been producing steadily and successfully at water depths greater than 5000 feet in several regions around the world. Such subsea wells are very expensive to drill and to complete. Thus, there is always a constant drive to keep such subsea wells producing for as long as possible to extract as much of the hydrocarbons from the formation as is economically feasible.
Over time, the production rates of subsea wells may be reduced to uneconomic levels. Another problem that is frequently encountered is that the natural pressure of the reservoir, or drive energy of the well, is insufficient to cause the flow of hydrocarbons out of the well at economically feasible quantities. Various artificial-lift methods have been developed to extend the useful life of such wells. The use of submersible pumps positioned in the well is one common technique that is employed to increase the flow rate of hydrocarbons to economically acceptable levels. Such pumps may take a variety of forms, e.g., an electrical submersible pump (ESP), a hydraulic submersible pump (HSP), a progressing cavity pump, a jet pump, etc. An ESP or an HSP typically includes a multistage centrifugal pump. An ESP is operatively coupled to and driven by an electric motor. An HSP is operatively coupled to a hydraulic motor. The ESP or HSP may be installed inside the well in a tubing string, and it is typically situated at a certain depth within the well. An ESP is powered via an electrical umbilical that includes an electric cable that is connected to a source of electrical power, e.g., a generator, positioned on a topside facility, e.g., a platform, a ship, etc. An HSP is powered via a hydraulic umbilical, a tubing or pressurized fluid in an annular space that includes a conduit for the supply of pressurized fluid to the HSP, wherein the conduit is connected to a source of pressurized hydraulic fluid, e.g., a pump that is positioned on a topside facility, e.g., a platform, a ship, etc. In other cases, the HSP may be powered via pressurized fluid supplied via a tubing or via pressurized fluid supplied via an annular space.
An ESP is typically positioned within a well or a Christmas tree by suspending it on the production tubing and strapping an electrical cable on the outside of the production tubing from the ESP to the wellhead or Christmas tree. The electrical cable is operatively coupled to the electrical motor portion of the ESP. Electrical connectors or penetrators are coupled to the opposite end of the electrical cable within the wellhead of Christmas tree production tubing hanger. Multiple electrical connections will be made to thereby establish electrical conductivity with the electrical umbilical so as to provide electrical power to the electrical motor portion of the ESP. A similar arrangement is made for HSPs except that a conduit, such as the annular space between the outside diameter of the production tubing and the inside diameter of the casing, extends between the HSP hanger and the HSP positioned down-hole. The conduit is operatively coupled to the hydraulic motor portion of the HSP, and high-pressure fluid is supplied to the hydraulic motor via the conduit so as to drive the pump portion of the HSP. Eventually a hydraulic connector that is in fluid communication with the conduit will be coupled to another hydraulic connector to thereby establish fluid communication with the hydraulic umbilical so as to provide a pressurized fluid to the hydraulic motor portion of the HSP. The working fluid for an HSP motor can be either a component of the fluid the HSP is pumping, or a separate working fluid dedicated to driving the HSP may be used.
A typical problem encountered with the use of ESPs relates to reliability or longevity of electrical connectors and other electric components, e.g., electric motors. It is frequently the case that the electrical components that are responsible for powering the pump in an ESP fail for one reason or another leading to well downtime and/or expensive repairs. A hydraulic powered submersible pump utilizes a more robust power delivery system which has a significantly longer mean time to failure than electrically powered submersible pump systems. However, as wells are being drilled in deeper and deeper water, the use of a hydraulic umbilical to supply pressurized fluid from a pump positioned on a topside facility to drive an HSP becomes more problematic. For example, in a closed-loop system, as the water depth increases, the liquid head that must be overcome when the drive fluid is returned to the surface is becoming a very significant factor as it relates to system design and quality.
In an effort to decrease the cost of replacing an electrical submersible pump that has failed, the traditional installation technique of attaching the ESP to the production tubing and strapping the electrical power cable to the outside diameter of the production tubing is being abandoned in favor of a method that does not require retrieval of the production tubing. Installing the ESP inside of the production tubing and conveying the ESP into the production tubing by a power cable, or a conduit containing power cabling such as coiled tubing or the like, is seen as a means to reduce the overall replacement costs, eliminating the time and effort required to pull the completion, however, this does not improve the mean time to failure of the ESP, it simply reduces the total cost of replacement.
The present disclosure is directed to various embodiments of a system for operating a hydraulically-powered submersible pump that may solve or reduce one or more of the problems identified above.
The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an exhaustive overview of the invention. It is not intended to identify key or critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is discussed later.
Generally, the present disclosure is directed to various embodiments of a system for operating a hydraulically-powered submersible pump that uses a pump positioned subsea to supply the pressurized fluid to drive the submersible pump. One illustrative system disclosed herein includes a submersible pump positioned in a well, a hydraulic motor that is operatively coupled to the submersible pump and a pressurized fluid supply pump that is positioned on or near a floor of the subsea environment and in fluid communication with the hydraulic motor.
Another illustrative system disclosed herein includes a production tree positioned above a well, a submersible pump positioned in the well, a hydraulic motor that is operatively coupled to the submersible pump, a booster pump that is adapted to receive a hydrocarbon fluid from a production outlet of the tree and a pressurized fluid supply pump that is positioned on or near a floor of the subsea environment, wherein the pressurized fluid supply pump is in fluid communication with the hydraulic motor. In further embodiments, the system may also include a separator that is adapted to receive a pressurized fluid from an outlet of the booster pump, and the pressurized fluid supply pump is in fluid communication with the hydraulic motor.
Yet another illustrative system disclosed herein includes a production tree positioned above a well, a submersible pump positioned in the well, a hydraulic motor that is operatively coupled to the submersible pump, a booster pump positioned on or near a floor of the subsea environment, wherein the booster pump is adapted to receive a hydrocarbon fluid from a production outlet of the tree, and a separator that is adapted to receive a pressurized fluid from an outlet of the booster pump, wherein the separator comprises a fluid outlet that is in fluid communication with the hydraulic motor.
Yet another illustrative system disclosed herein includes a production tree positioned above a well, a submersible pump positioned in the well, a hydraulic motor that is operatively coupled to the submersible pump, a booster pump positioned on or near a floor of the subsea environment, wherein the booster pump is adapted to receive a hydrocarbon fluid from a production outlet of the tree, and a valve that is in fluid communication with an outlet of the booster pump and adapted to receive a pressurized hydrocarbon fluid from the outlet of the booster pump and direct a portion of the pressurized hydrocarbon fluid to the hydraulic motor.
Yet another illustrative system disclosed herein includes a production tree positioned above a well, a submersible pump positioned in the well, a hydraulic motor that is operatively coupled to the submersible pump, a booster pump that is adapted to receive a hydrocarbon fluid from a production outlet of the tree, a pressurized fluid supply pump that is positioned on or near a floor of the subsea environment, wherein the pressurized fluid supply pump is in fluid communication with the hydraulic motor, and a turbine comprising a shaft that is operatively coupled to the pressurized fluid pump, the turbine being in fluid communication with an outlet of the booster pump and adapted to receive a pressurized hydrocarbon fluid from the outlet of the booster pump, wherein the shaft is adapted to be rotated by the pressurized hydrocarbon fluid, and wherein the shaft is further adapted to drive the pressurized fluid pump via rotation of the shaft.
The disclosure may be understood by reference to the following description taken in conjunction with the accompanying drawings, in which like reference numerals identify like elements, and in which:
While the subject matter disclosed herein is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.
Various illustrative embodiments of the invention are described below. In the interest of clarity, not all features of an actual implementation are described in this specification. It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developers' specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.
The present subject matter will now be described with reference to the attached figures. Various structures, systems and devices are schematically depicted in the drawings for purposes of explanation only and so as to not obscure the present disclosure with details that are well known to those skilled in the art. Nevertheless, the attached drawings are included to describe and explain illustrative examples of the present disclosure. The words and phrases used herein should be understood and interpreted to have a meaning consistent with the understanding of those words and phrases by those skilled in the relevant art. No special definition of a term or phrase, i.e., a definition that is different from the ordinary and customary meaning as understood by those skilled in the art, is intended to be implied by consistent usage of the term or phrase herein. To the extent that a term or phrase is intended to have a special meaning, i.e., a meaning other than that understood by skilled artisans, such a special definition will be expressly set forth in the specification in a definitional manner that directly and unequivocally provides the special definition for the term or phrase.
The present disclosure is directed to various embodiments of a system for operating a hydraulically-powered submersible pump that uses a pump positioned subsea to supply the pressurized fluid to drive the submersible pump.
With continuing reference to
In terms of general operation, in one embodiment, the subsea PFS pump 60 is adapted to supply a pressurized fluid 70 to the hydraulic motor 30HM via the tubing 32, e.g., coiled tubing. The HSP 30 is positioned below the level of hydrocarbons (liquid and/or gas) in the well 11. The pump 30P of the HSP 30 has an intake 30A where hydrocarbons enter the pump 30P. As is known to those skilled in the art, the pressurized fluid 70 causes the hydraulic motor 30HM to rotate, which in turn, in the case where the submersible pump 30P is a centrifugal pump, causes the submersible pump 30P to rotate and thereby increases the pressure of the hydrocarbon fluids as they pass through the pump 30P. More specifically, hydrocarbons enter the pump 30P, as schematically depicted by the arrow 80, and leave the pump 30P as a pressurized hydrocarbon fluid 82 via various outlets (not shown) in the pump 30P. The pressurized hydrocarbon fluid 82 is discharged into the annular space 13 between the production tubing 14 and the tubing 32. The discharged fluid 70R from the hydraulic motor 30HM, which is now at a relatively lower pressure, leaves the hydraulic motor 30HM via various outlets (not shown), and, in this embodiment of the system 10, is also discharged into the annular space 13 between the production tubing 14 and the tubing 32 where it co-mingles with the pressurized hydrocarbon fluid 82 that passed through the pump 30P. The production tree 20 includes a production outlet 20A where a production fluid 90 (a combination of the pressurized hydrocarbon fluid 82 and the discharged fluid 70R) exits the tree 20 and flows to other processing equipment, described more fully below, for further processing.
As will be recognized by those skilled in the art after a complete reading of the present application, the various systems 10 disclosed herein may be implemented using either open-loop or closed-loop type pumping systems. Moreover, it should be understood that the PFS pump 60 depicted herein is intended to be representative in nature in that it represents any type of pump that may be used to increase the pressure of a fluid (gas or liquid, or a combination thereof) as it passes through the PFS pump 60. The PFS pump 60 may have any type of configuration, e.g., a centrifugal type pump, a positive displacement type pump, etc., it may be of any size or horsepower, and it may be adapted to pump a single phase fluid or a multi-phase fluid. In one illustrative embodiment, the PFS pump 60 may be an electrical pump that is powered and controlled via an electrical umbilical (not shown) that is connected to an electrical power supply source positioned on a topside facility, e.g., a platform. Thus, the PFS pump 60 should not be considered as limited to any particular type or form of pump. In one particular embodiment, the PFS pump 60 is of a size such that it alone is adapted to increase a pressure of a hydrocarbon fluid so that hydrocarbon fluid may flow from a floor of the subsea environment to a surface of the subsea environment without the need to further increase the pressure on the hydrocarbon fluids. The tubing 32 is also intended to be representative of any type of conduit, e.g., coiled tubing, that may be employed in a well to conduct and contain a pressurized fluid from one location to another location.
With reference to
The particular embodiments disclosed above are illustrative only, as the invention may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. For example, the process steps set forth above may be performed in a different order. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the invention.
Accordingly, the protection sought herein is as set forth in the claims below.
Filing Document | Filing Date | Country | Kind |
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PCT/US2012/059652 | 10/11/2012 | WO | 00 |