Patent Publication Number: US-10774622-B2

Title: Pipeline booster pump system for promoting fluid flow

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a US national stage application claiming priority to Patent Cooperation Treaty (PCT) Application No. PCT/US17/53808, filed 27 Sep. 2017, which in turn claims priority to U.S. Provisional Application No. 62/400,571, filed 27 Sep. 2016. Both prior applications are titled “Pipeline Booster Pump System For Promoting Fluid Flow,” and their full contents are incorporated herein by reference. 
    
    
     FIELD OF THE APPLICATION 
     The application relates generally to promoting flow or transfer of fluids through subsea conduits to a surface and/or production facility. 
     BACKGROUND 
     In a variety of subsea applications, the production of oil, hydrocarbons, or other production fluids from subsea production zones may be limited, restricted, or written off entirely due to the presence of water within the production zone. Specifically, as the production fluids are produced from a zone, and as the zone depletes, water may permeate into the pipeline, decreasing the production, lowering the pressure or the production zone, and generally hindering profitability of a well system. In some instances, this decrease in productivity, caused by the influx of water, necessitates the temporary shutdown of a well system, or a complete abandonment of a reserve as unprofitable. Additionally, fluids from the subsea production zones may be directed from one locale to another. Depending on the activity, fluid may be directed through subsea flowlines located on the seafloor or directed upwardly from a subsea well, pipe or pipeline, pipeline end termination (PLET), a vessel, or other container to the water surface. In some cases a subsea pump is used to direct subsea fluids from one locale to another. 
     In one known subsea pumping technique, hydraulic drive systems have been employed for powering subsea pumps. However, the motor powering the pump may have to overcome a given hydrostatic pressure when returning motor fluids back to the water surface, and the result may include a time intensive endeavor placing an unwanted load on the motor powering the subsea pump. 
     In another known subsea pumping technique, electric drive systems have been employed to power subsea pumps. However, at great depths it may be difficult to supply the necessary current and amperage to effectively pump fluids to the water surface. 
     A more efficient technique for transporting subsea fluid and maintaining productivity in subsea production zones is desired. 
     In petroleum production, oil and its byproducts are typically removed from wells and transported through pipelines, including subsea pipelines. The flow of oil and other fluids through a subsea pipeline can lead to the buildup of different substances within the pipe impeding fluid flow there through. For example, scale, paraffin wax, wax plugs, paraffin plugs, hydrates, ice plugs, asphaltenes, debris or sand may build up in the pipeline over time depending on the nature of the fluid flowing through the pipeline and other surrounding circumstances. 
     One method to prevent the formation of paraffin deposits is to heat the pipelines. However, this method is very expensive and is not feasible for subsea pipelines submerged in the cold sea water. 
     Another method involves “pigging”, wherein a mechanical device is passed through the pipeline scraping the inner wall of the pipeline and pushing paraffin deposits through. However, the pigging tools (e.g., mechanical tools used for maintenance) then require removal, from the pipeline or well, for increasing or restoring the flow of hydrocarbons from subsea environments. 
     Another method for removing paraffin deposits is “hot oiling,” wherein a heated oil is pumped through the pipeline in order to remove the paraffin wax deposits. However, again this can be expensive and not very feasible for subsea environments. 
     Another cause of blockage in subsea pipelines is the formation of gas hydrates where an aqueous phase is inherently present, during the transportation of fluids including gases. This is a common problem, especially in deep sea conditions including low temperatures and/or high pressures. Low temperatures and the presence of water can lead to the formation of these gas hydrates in the pipelines. 
     One method of dealing with gas hydrates is to insulate the pipeline. But, this approach is typically expensive. Another method is to pump methanol through the pipeline or to use chemical methods, such as addition of anti-agglomerates (e.g. kinetic inhibitors or thermodynamic inhibitors). However, to be effective, large quantities of these chemicals are required making the process expensive. 
     Other problems associated with production of hydrocarbons can include increased hydrostatic pressure due to the accumulation of water in the pipeline or producing zone (e.g., a pipeline, a PLET, a producing well, or combinations thereof). Accordingly, improved systems and methods are needed for providing the flow, or increasing the flow, of hydrocarbons form a subsea environment to a surface and/or production facility. 
     SUMMARY 
     The present application is directed to a pumping system operable at the surface (e.g., a surface platform) for increasing or restoring the flow of hydrocarbons, from a subsea environment to a surface and/or surface production facility. 
     One embodiment of the present invention is directed to a subsea pipeline booster pump system, the system comprising a primary conduit forming a fluid connection between a valve assembly and a production zone, a Y-block fluidly connected to the valve assembly, wherein the Y-block divides the primary conduit into an open secondary conduit and a pump secondary conduit, wherein the pump secondary conduit comprises a pump assembly internal to the pump secondary conduit, wherein the pump assembly comprises a progressive cavity pump. 
     This embodiment may further comprise at least one valve between the Y-block and the open secondary conduit, at least another valve between the Y-block and the pump secondary conduit, or at least one emergency quick disconnect (EQD), the EQD selectively releasing the at least one valve, the at least another valve, or both, from the Y-block. This EQD can be operationally configured to release upon receiving an electric or acoustic signal initiated from the surface. The open secondary conduit may comprise a clear fluid path leading to a production facility, while the pump secondary conduit is in fluid communication with the production facility. Embodiments may include switch valves between the production facility and the secondary conduits to selectively control fluid communication, anchoring sections within the pump assembly securing it to a specific location along the inner wall of the pump secondary conduit (through, e.g., compressible packers, bolts, locks, clips, hooks, or other latch mechanisms). 
     A further method embodiment is directed to a method of pumping fluid from a subsea environment to a surface production facility, the method comprising attaching a primary conduit to a pipeline or pipeline end termination, splitting the primary conduit into an open secondary conduit and a pump secondary conduit by means of a Y-block, connecting the open secondary conduit to the surface production facility, and powering a motor and a progressive cavity pump located within the pump secondary conduit. 
     The method embodiment may further comprise attaching at least one emergency quick disconnect (EQD) system between the Y-block and the open secondary conduit, or between the Y-block and the pump secondary conduit, wherein the EQD system disconnects the Y-block from the open secondary conduit and the pump secondary conduit upon receipt of a signal from the surface production facility. Embodiments may include wherein the step of powering the motor and progressing cavity pump involves hydraulics, electric power, pneumatics, or combinations thereof, or wherein the step of attaching the primary conduit to the pipeline or pipeline end termination comprises attaching a valve assembly on a surface platform to a deep water or ultra deep water production zone. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates an embodiment of a pipeline booster pump system that may be used in production of fluid comprising hydrocarbons from a subsea production zone. 
         FIG. 2  illustrates an embodiment of a pipeline booster pump system that includes an emergency quick disconnect used in the production of fluid comprising hydrocarbons from a subsea production zone. 
         FIG. 3  illustrates an embodiment of a progressive cavity pump (PCP) usable in an embodiment of the pipeline booster pump system. 
         FIG. 4  provides dimensions associated with a particular type of PCP pump, a simplified PCP pump, usable in an embodiment of the pipeline booster pump system. 
     
    
    
     DETAILED DESCRIPTION 
     The present application relates, generally, a pumping system that is operable at the surface (e.g., a surface platform) for increasing or restoring the flow of hydrocarbons, from a subsea environment to a surface and/or surface production facility. 
     A motor may be used as a prime mover for a pump system to transfer fluids found in subsea environments, and maybe usable in such activities as hydrate recovery or remediation, pipeline abandonments, dewatering pipelines, subsea well kill operations, well draw downs, and for flushing subsea pipelines by increasing the flow rate of fluid to the surface of the water as compared to the flow rate generated by electric motors and hydraulic motors. In operation, the motor can be suitably powered by hydraulics, electric power and/or pneumatics. In an embodiment, the pump can be a progressive cavity pump (PCP or corkscrew pump). 
     Before describing the invention in detail, it is to be understood that the present system and method are not limited to particular embodiments. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting. As used in this specification and the appended claims, the phrase “motor” refers to a hydraulic motor, electric motor, and/or pneumatic motor. The phrase “deep water” includes subsea depths from about 914 m to about 2286 m (about 3,000 feet to about 7,500 feet). The phrase “ultra deep water” includes subsea depths of about 2286 m or more (about 7,500 feet or more). The term “PLET” stands for pipeline end termination. The phrase “surface platform” refers to a floating vessel, a stationary platform above the surface of the water, or dry land. The term “pipeline” refers to a conduit made from pipes connected end-to-end for fluid transport, including but not necessarily limited to petroleum conduits located above ground, underground, and subsea. The phrase “sea water” refers to water originating from the lake, sea, or ocean in which the present system is operating. The acronym “BPM” refers to barrels per minute. The acronym “LPM” refers to liters per minute. The acronym “GPM” refers to gallons per minute. The term “surface” as such relates to the present subsea system refers to the water surface of the body of water containing the system. Rotatable and turnable devices include those devices acted on by a corresponding drill motor of this application. Without limiting the types of rotatable and turnable devices, suitable devices for subsea purposes may include the rotating armature of a motor, pump or generator. 
     In one aspect, the application provides a system providing for the conveyance of fluid from a subsea locale to a surface locale. 
     In another aspect, the application provides a means for pumping fluid from a subsea environment to the surface using a pump (e.g., PCP pump) powered by a motor, the motor in turn being powered by hydraulics, electricity, and/or pneumatics. 
     In another aspect, the application provides a system and method for pumping fluid from a subsea location to the surface using a motor and a pump (e.g., PCP). The system can include a flex-shaft seal assembly coupled to the pump rotor to compensate for the eccentric rotation and vibration of the pump. 
     In another aspect, the application provides a system and method for subsea pipeline hydrate remediation. 
     In another aspect, the application provides a system and method for subsea pipeline blockage or plug remediation, including hydrate plugs or ice plugs, wax plugs, paraffin plugs, sand debris, and other debris forming blockages or plugs. 
     In another aspect, the application provides a system and method for pipeline “pigging,” as the term is known to persons of ordinary skill in the petroleum industry, including the removal of the pipeline pigging tools. 
     In another aspect, the application provides a system and method for dewatering pipelines in deep water and ultra deep water. 
     In another aspect, the application provides a system and method for chemical injection into subsea pipelines in deep water and ultra deep water, and/or the removal of chemicals from subsea pipelines and/or wells. 
     In another aspect, the application provides a system and method for moving fluid from a subsea location to the surface of the water at a hydrostatic pressure up to about 463 bar (about 6708 psi). 
     In another aspect, the application provides a system and method for pumping fluid from a subsea pipeline at a depth of about 2134 meters (about 7,000 feet) to the surface of the water at a rate about 75 liters (about 20 gallons) or more per minute. 
     In another aspect, the application provides a system operationally configured to pump fluid from such depth to the water surface at a rate of about 227 liters (about 60 gallons) or more per minute. 
     In another aspect, the application provides a system and method effective for dropping pressure within a pipeline downstream of an ice plug or other plug or blockage. 
     In another aspect, the application provides a system operationally configured to be tested, repaired or otherwise serviced above the surface of the water. 
     In another aspect, the application provides a system including at least a motor, pump, valve assembly, and y-block for connecting to a pipeline to increase or restore the flow of hydrocarbons, to a production facility. The system can include an emergency quick disconnect as described below. 
     In another aspect, the application provides a system that may be built to scale. 
     In another aspect, the application provides a system located on or tethered to a surface platform or vessel. Alternatively, the system may be located on or tethered to one or more land based components. 
     In another aspect, the application provides a system that meets all required American Petroleum Institute (“A.P.I.”) tolerances. In another aspect, the system tolerances are greater than the corresponding A.P.I. tolerances. 
     In another aspect, the application provides a system operationally configured for deep water or ultra deep water pumping of fluid from the seafloor to the surface, the system being operationally configured to recover about seven times more fluid from a subsea locale than is necessary to power a pump means. 
     To better understand the novelty of the system and method of use thereof, reference is hereafter made to the accompanying drawings. With reference to  FIG. 1 , a simplified illustration of a pipeline booster pump system  10  is provided. Suitably, the system  10  may be installed as an above-sea finishing pump to a subsea system that includes a motor  46 . With reference to  FIG. 1 , the system  10  may be configured to operate in conjunction with one or more fluid sources (e.g., hydrocarbons, natural gas, water, etc.) or production zones  12  to produce increased fluid flow of the fluid (e.g., hydrocarbons, natural gas, water etc.). For example, the present system  10  may be operationally configured for boosting production in depleted production zones, dewatering pipelines, subsea hydrate recovery or remediation, plug remediation, dewatering purposes, flushing purposes, cleaning purposes, evacuation purposes, recovery purposes, testing pipeline integrity, pipeline maintenance and combinations thereof. In a particularly advantageous embodiment, the system  10  may be operationally configured for use at the surface where fluid is being produced from deep water or ultra deep water environments. 
     The system  10  may be installed in or on a surface platform, and may comprise at least one motor, at least one pump, at least one valve assembly (e.g., dual valve assembly, additional valve assembly), and a y-block assembly. The system  10  can include an emergency quick disconnect as discussed below. 
     Fluid flow within the system  10  is provided via fluid conveyance (hereafter referred to as “conduit”), which may include conventional metal piping, coiled tubing, flexible hose, flexible piping, and combinations thereof. As shown, a conduit  14  (e.g., pipeline) is operationally configured to provide a fluid connection between a valve assembly  16  on the surface platform and the production zone  12  for conveying fluid from the subsea environment to a surface and/or a production facility  18 . It will be understood that the conduit  14  may include one or several pipes, tubes, tubulars, or layers of such for enabling the flow of the fluid from the subsea environment to the surface. As described above, the production fluid from the production zone  12  may, over time, become less productive and, as such, have a measurable decrease in the pressure in the production fluid. In addition, the decrease in production fluid may allow water (e.g., sea water) to permeate the production zone and flow into the conduit  14 , further decreasing the flow of fluid within the pipeline. 
     For times when the production zone operates with an excess of pressure, or the booster pumping system can create the pressure needed for the flow of the fluid, the system  10  includes a y-block  20 . The y-block  20  divides the fluid flow from into the open conduit  22  and the pump conduit  24 . The open conduit  22  includes a clear path for the production fluid, which enables fluid to flow cleanly to the production facility  18 . The open conduit  22  may include one or more valves  26  to ensure that the production fluid does not build up pressure in any unwanted location along the open conduit  22 . The pump conduit  24  likewise includes valves  28  (e.g., dual valve assembly) for related purposes, and is likewise fluidly connected to the production facility  18 . Switch valve  48  enables selective communication from the production facility  18  to the open conduit  22  and the pump conduit  24 . While the illustrated embodiment shows two valves  28 , certain embodiments may have one valve  28 , three valves  28 , four valves  28 , or more depending on the pressures being pumped and the needs of the system  10 . The system  10  may also include at least one emergency quick disconnect (EQD)  30  for releasing the valves  26 ,  28  from the y-block  20  for maintenance, treatment, replacement, or other servicing of the system  10 . 
     The pump conduit  24 , in certain embodiments, includes a pump assembly  40  for pumping production fluid, water, gas, contaminants, or other chemicals or fluids from the pump conduit  24 . The illustrated pump assembly  40  includes an anchoring section  42  and a pump  44 . The anchoring section  42  includes a number of components that secure the pump assembly  40  into a specific location within the pump conduit  24 . For example, the anchoring section  42  may include packers or other compressible members that seal the space between the anchoring section  42  and the pump conduit  24 . The anchoring section  42  may also include bolts, locks, clips, hooks, or other latching means to keep the pump assembly  40  in place so that the pump  44  can operate without moving, such as attaching to a wall. 
     Although not necessarily limited to a particular means for producing fluid flow, a suitable pump  44  for use within the pump conduit  24  includes a corkscrew pump. In a particularly advantageous embodiment, the pump includes a progressive cavity pump or “PCP pump” as understood by persons of ordinary skill in the art. Although not necessarily limited to a particular type of PCP pump, a simplified PCP pump is depicted in  FIG. 3  with corresponding dimensions listed in  FIG. 4 . 
     Suitably, the motor  46  and pump  44  can be coupled in a manner effective for the motor  46  to operationally power the pump  44  to recover fluids from subsea environments. 
     Although not necessarily limited to a particular type of connection, the motor  46  and pump  44  may connect to the valve assembly  28 , as shown in  FIGS. 1 and 2 , that can connect to an emergency quick disconnect (EQD)  30 , commonly referred to as “hot stabs” by persons of ordinary skill in the art of subsea pumping operations. In one aspect, a suitable emergency quick disconnect  30  is operationally configured to prevent any ambient water ingress into the motor, pump, and valve assembly during system operation. In another aspect, the emergency quick disconnects are operationally configured to allow the pumping system to release from the pipeline in an emergency situation. In operation, the emergency quick disconnects are operationally configured to release the attached pumping system, e.g., via an electric signal or an acoustic signal initiated from the surface. Although the system may be built to scale, including the emergency quick disconnects, suitable disconnects can range in size from about 5.08 cm to about 10.16 cm (about 2.0 inches to about 4.0 inches). 
     In operation, the motors(s)  46  can act as prime mover(s) for the corresponding pump  44 , which in one aspect is effective for forming a vacuum on the pipeline resulting in the flow of pipeline fluids and hydrates into a conduit through the pipeline. The hydrate, or other plug or blockage, can be found in the pipeline, a pipeline end termination (PLET), a producing well or any combination thereof. As understood by persons of ordinary skill in the art, a typical subsea pipeline terminates at PLET—a structure that provides a connection of the pipeline to other system components. A suitable PLET includes a foundation that vertically supports the pipeline, the weight of one or more end connectors, and any valves employed. As shown, the PLET may also include a hub connector, a vertical connector or similar device operationally configured to act as a tie-in connection between the pipeline and the pumping system components. 
     As stated above, the present system  10  may be employed for boosting production in depleted production zones, dewatering pipelines, subsea hydrate recovery or remediation, plug remediation, dewatering purposes, flushing purposes, cleaning purposes, evacuation purposes, recovery purposes, testing pipeline integrity, and combinations thereof. 
     Persons of ordinary skill in the art will recognize that many modifications may be made to the present application without departing from the spirit and scope of the application. The embodiment(s) described herein are meant to be illustrative only and should not be taken as limiting the invention, which is defined in the claims.