Through tubing pumping system with automatically deployable and retractable seal

A downhole pumping system in production tubing having a seal between the intake and discharge of a through tubing downhole pump that automatically deploys when the pump initiates operation. The seal automatically disengages when the pump suspends operating and redeploys when the pump starts operating again. The pumping system can be set at a different depth before restarting the pump. The seal can include a bladder like member that has an opening facing towards the pump discharge, so that discharged fluid expands the bladder radially outward into sealing contact with the tubing.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a device for use in producing fluid from a wellbore. More specifically, the invention relates to a system and method for sealing an annular space between a pump and production tubing.

2. Description of the Related Art

Hydrocarbon producing wellbores extend subsurface and intersect subterranean formations where hydrocarbons are trapped. The wellbores are typically lined with casing and have production tubing inserted within the casing. Artificial lift is often relied on for producing hydrocarbons from within a formation when downhole pressure is insufficient for transporting produced liquids to the surface. Typically, artificial lift during oil and gas production uses pumping in the wellbore to lift fluids from downhole to surface and push them to processing facilities. Some pumping systems are integrated with production tubing and conveyed downhole with the production tubing. Other pumping systems are deployed downhole through already installed production tubing and suspended from coiled tubing or power cable.

Through tubing deployed pumping systems require isolation between pump intake and discharge, otherwise fluid exiting the pump can flow back downhole and enter the pump intake and be re-circulated through the pump. An example of an existing isolation technique presets a landing profile (e.g., seal bore) on the tubing. As the pumping system is installed, a seal assembly or seating shoe on the pumping system engages with the landing profile, thus sealing off the fluid path between pump intake and discharge.

It is not uncommon for the pump to be moved to a different depth during the life of the well to compensate for changes in reservoir pressure, water cut or productivity changes and optimize system performance. Changing pump setting depth though requires a workover rig to pull out the tubing and re-install the landing profile at a different depth.

SUMMARY OF THE INVENTION

Disclosed herein is an example of a downhole assembly for use in production tubing. In one embodiment the downhole assembly has a pump with a pump inlet and a pump discharge, a motor for driving the pump, and a seal between the pump inlet and pump discharge. In this example the seal is made up of a membrane like member shaped to define an opening facing the pump discharge. When fluid flows from the pump discharge, the discharged fluid enters the opening and urges a portion of the membrane adjacent the opening radially outward so that the membrane fills an annular space between the outer surface of the downhole assembly and production tubing and blocks discharged fluid from entering the pump inlet. Optionally, a lower end of the member distal from the pump discharge is clamped around the outer surface; in this example the member has a stowed position where it is disposed proximate an outer surface of the outer surface. The member is moveable to a deployed position having a cup like shape, wherein an upper end of the member proximate the pump discharge flares radially outward into contact with the tubing. In one alternative, a lower end of the member distal from the pump discharge is clamped around the outer surface and an upper end of the member proximate the pump discharge is secured to the outer surface so that a gap is between the upper end and the outer surface that defines the opening. In this alternate example, a middle portion of the member flares radially outward into contact with the tubing when discharge fluid flows into the opening. An anchoring system may optionally be included with the downhole assembly, where the anchoring system mounts onto an outer surface of the assembly and includes a plurality of anchoring legs. In this example, a portion of each anchoring leg selectively projects radially outward into contact with an inner surface of the tubing. An actuator is optionally mounted on the outer surface that selectively biases against ends of the anchoring legs for projecting the anchoring legs radially outward. In one example, the membrane like member is made up of an annular bladder. In an alternate embodiment, the seal includes a lower bracket that sealingly couples around the outer surface and an upper bracket that circumscribes the outer surface and is set radially outward from the outer surface. Yet further optionally, an upper end of the bladder mounts to the upper bracket and a lower end of the bladder mounts to the lower bracket. In one optional example, the membrane like member has a lower end that pivotingly mounts to the outer surface and an upper end with an outer periphery that defines the opening. Also, folds may be included in the membrane between the lower end and upper end. This embodiment may optionally include rib supports that extend along a path between lower and upper ends of the membrane and coupled with the membrane. Struts may also be included, where each strut has an end pivotingly mounted to an upper bracket that circumscribes the outer surface and a distal end pivotingly coupled to a one of the rib supports.

Also described herein is a wellbore assembly insertable in a tubular disposed in a wellbore. In one example the wellbore assembly includes a pump having a discharge and an annular inlet that depends axially from an end of the pump. A seal assembly is included that circumscribes the annular inlet and that includes; a lower bracket sealingly mounted to an outer surface of the annular inlet, a membrane having a lower end coupled to the lower bracket and an outer periphery that selectively projects radially outward into sealing contact with an inner surface of the tubular. The membrane is radially extended in response to a fluid flowing from the discharge and into a space between the membrane and the annular inlet. The wellbore assembly can further include an upper bracket that circumscribes the annular inlet an axial distance from the lower bracket. In this example an upper end of the membrane is coupled to the upper bracket. In one example, the upper bracket is spaced radially outward from the annular inlet. In one alternate embodiment, the wellbore assembly further includes an anchoring system made up of elongated linkage members disposed at circumferential positions around the annular inlet, upper ends mounted in an upper collar, and lower ends mounted in a lower collar. In this example, an actuator is included for selectively biasing the upper collar towards the lower collar and causing the mid portions of the linkage members to extend radially outward from the annular inlet and into engagement with an inner surface of the tubular. In an example embodiment, the membrane has an elliptical shape when the outer periphery projects radially outward. Optionally, the membrane like member has a lower end that pivotingly mounts to an outer surface of the annular inlet and an upper end with an outer periphery that defines an opening, folds may be included in the membrane that are between the lower end and upper end. Also optionally in the membrane are rib supports extending along a path between lower and upper ends of the membrane and coupled with the membrane. Alternatively, struts may be included that each have an end pivotingly mounted to an upper bracket that circumscribes the outer surface and a distal end pivotingly coupled to a one of the rib supports.

A method of pumping fluid from a wellbore is also disclosed herein. In one example the method includes providing a wellbore assembly that includes a pump having an inlet and a discharge, and a seal assembly. In this example the seal assembly has a toroidally shaped membrane with a lower end sealed against an outer surface of the wellbore assembly and an upper end spaced radially outward from the outer surface to define an opening. The method of this embodiment further includes disposing the wellbore assembly in a tubular in the wellbore and forming a seal between the wellbore assembly and the tubular. The seal is formed by using the pump to pressurize fluid produced from the wellbore, and flowing the pressurized fluid from the discharge to the opening to radially expand the membrane into sealing engagement with the tubular. The method can also include suspending pump operation so the membrane radially retracts from the tubular, moving the wellbore assembly to a different depth in the wellbore, and reforming the seal at the different depth. In one example, the seal isolates fluid produced from the wellbore from fluid being discharged from the pump.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

Shown inFIG. 1Ais a side partial sectional view of an example of an electrical submersible pumping (ESP) system10disposed within a length of production tubing12. In an example embodiment, the ESP system10is used for pumping fluids from within a wellbore13shown lined with casing14. An optional packer16is illustrated set in the annular space18between the tubing12and casing14, where the packer16forms a flow barrier in the annular space18. The ESP system10ofFIG. 1Ais suspended within the tubing12on a lower end of a power cable20. Electricity for powering the ESP system10can be delivered through the power cable20. Optionally, the power cable20can also deliver control signals from a controller (not shown) to the ESP system10. An annular pump inlet22having an opening23on its lowermost end is shown depending downward from a lower end of a pump24. In an example, fluids produced from the wellbore13are directed to the pump24through the pump inlet22. Above the pump24are a series of ports26that define a pump exit through which fluid discharges after being pressurized in the pump24. A pressure compensating seal28is included shown disposed above the ports26and having on its upper end a motor30for driving the pump24. In one example, a pump shaft (not shown) connects the motor30to the pump24.

An isolation device32is shown circumscribing a portion of the annular pump inlet22. In the embodiment ofFIG. 1A, the isolation device32includes a membrane like barrier34set between an upper bracket36and lower bracket38. The barrier34as shown in the example ofFIG. 1A, is in a stowed position and set proximate to an outer surface of the pump inlet22. Optionally, the isolation device32can be set on other portions of the ESP system10. Other embodiments have the isolation device32anywhere between the opening23on the inlet22and ports26.

Still referring toFIG. 1A, the lower end of the barrier34is affixed around the pump inlet22by the lower bracket38. The upper end of the barrier34however can freely move in a direction radially outward from the outer surface of the inlet22. As will be discussed in more detail below, the barrier34has an outer circumference that increases with distance away from the lower bracket38and towards the upper end of the barrier34. To allow the increasing diameter of the barrier34to be in the stowed position ofFIG. 1A, a series of folds40are shown optionally formed in the barrier34.

Arrows A representing fluid produced from within the wellbore13are shown within the tubing12and directed towards the opening23in the inlet22. In the configuration ofFIG. 1A, the produced fluid can flow unimpeded within the annulus42defined between the ESP10and inner surface of the tubing12. Activation of the motor30to drive the pump pressurizes the portion of the produced fluid drawn into the inlet22and discharges the pressurized fluid (represented by arrows exiting the ports26) into the annulus42. Because the discharged fluid has a pressure greater than the produced fluid, at least some of the discharge fluid will flow downward within the annulus and towards the isolation device32.

Referring now toFIG. 1B, the isolation device32is shown in a deployed configuration wherein the upper end of the barrier34has expanded radially outward and into sealing contact with the inner surface of the tubing12. The radial expansion of the barrier34is caused by the flow of the discharged fluid from the ports26, into the annular space42between the ESP system10and tubing12, and towards the barrier34. Directing a flow of pressurized fluid from the ports26and across the upper end of the barrier34, separates the upper free end of the barrier34from the surface of the ESP system10from the stowed configuration ofFIG. 1Ainto the open and deployed configuration ofFIG. 1B. As shown inFIG. 1B, the upper end of the barrier34sealingly contacts against the inner surface of the tubing12while the lower bracket38retains the lower end of the barrier34against the ESP system10. While in the deployed configuration, the barrier34thus defines a pressure barrier within the annulus42that separates produced fluid flowing into the pump inlet22from the discharged fluid exiting the ports26. In an example, the isolation device32will remain in the deployed configuration as long as the pump24remains operational and forces pressurized discharge fluid from the ports26so that a pressure differential exists across the barrier34. Optional support ribs43are shown included with the embodiment of the barrier34ofFIG. 1B, where the ribs43are elongate members integral with or attached to the barrier34and extend in a general direction from a lower end of the barrier34to its upper end. Struts44may optionally be included that each pivotingly attach on one end to the upper bracket36and pivotingly attach on a distal end to one of the ribs43. The combination of the ribs43and struts44provides structural support for the barrier34, such as for when the barrier34is deployed as inFIG. 1Band subjected to a pressure differential. In an example embodiment, deployment of the barrier34as illustrated inFIG. 1Boccurs automatically with operation of the pump24.

In an example alternative, operation of the pump24can be momentarily suspended while the ESP system10is repositioned within the tubing12to a different depth. While being repositioned, the barrier34can migrate into the stowed configuration ofFIG. 1A. Once set at the different depth, operation of the pump24may be resumed by powering the motor30thereby reverting configuration of the barrier34into the deployed position ofFIG. 1Bfrom the stowed position ofFIG. 1A. An optional controller45is shown that can be used for operation of the pump24and via connection to the power cable20. In this configuration, control signals may be made via the power cable and to the pump motor30. The controller45can be disposed at surface or downhole.

An axial view of the isolation device32is provided inFIG. 2taken along lines2-2. As shown in the embodiment of the isolation device32ofFIG. 2, a series of plates46are shown set on an inner surface of barrier34, where each plate46has a trapezoid like configuration. The shorter side of each of the two parallel sides of the trapezoidal like plate46is pivotingly anchored adjacent the lower bracket38. When the barrier34is in the deployed position, the upper planar surfaces of each of the plates46are slidingly sandwiched against one another. When deployed, as in the example ofFIG. 2, the plates46may slightly fan out from one another and provide support for the barrier34during its sealing function against the wall of the tubing12. Example materials for the plates46include metals, composites, combinations thereof, and the like.

FIGS. 3A and 3Billustrate in side partial sectional view operation of an alternate example of an ESP system10A. In the example ofFIG. 3A, the ESP system10A includes an annular pump inlet22A connected onto the lower end of the pump24A and ports26A that define a discharge for the pump24A. The equalizing seal28A and motor30A are also shown as part of the ESP system10A ofFIG. 3A, which in an example are similar to the respective seal28and motor30ofFIG. 1A. The ESP10A ofFIG. 3Aalso includes an isolation device32A having a barrier34A that resembles a bladder like membrane. The lower end of the barrier34A is sealingly mounted to the outer surface of the pump inlet22A by lower bracket38A. Upper bracket36A secures upper end of the barrier34A around an axial portion of the pump inlet22A. Further included with the ESP assembly10A ofFIG. 3Ais an anchor48that circumscribes the pump inlet22A at a location just above upper bracket36A. The anchor48includes a series of linkage members50having one of their ends pivotingly mounted into an upper collar52. The upper collar52ofFIG. 3Adefines an upper end of the anchor48. Another series of linkage members50each have an end pivotingly mounted into a lower collar54shown coaxially adjacent with upper bracket36A and below upper collar52. Ends of linkage members50respectively distal from the upper and lower collars52,54extend towards one another and couple within landing pads56shown within the mid portion of the anchor48and between the upper and lower collars52,54. Optionally, each linkage member50may have one end within the upper collar52and its opposite end set within the lower collar54; so that along their respective mid-portions, each of the linkage members50intersect a landing pad56.

An example of an actuator58is illustrated set above the anchor48and is provided for actuating the anchor to retain the ESP system10A within the tubing12. The example actuator58as shown includes a base60with arms62that depend axially downward and into contact with the upper collar52of the anchor48. In one example, the base60is an annular member that couples on an outer surface of the pump inlet22A and provides a support for the arms62to exert an axial force onto the upper collar52. Control and power may be provided to the actuator58via a line64that connects to the power cable20A. Optionally, a battery (not shown) can be included with the ESP system10A for powering the system alone or in combination with power delivered via the power line20A.

Referring now toFIG. 3B, illustrated in side sectional view is an example of operation of anchoring the ESP system10A. In this example the arms62of the actuator58extend away from the base60and urge the upper collar52downward along the outer surface of the pump inlet22towards the lower collar54. The pivoting attachment of the linkage members50with the upper collar52and lower collar54causes the landing pads56to project radially outward and into contact with the inner surface of the tubing12. In an example, the landing pads56exert a force onto the tubing12sufficient to prevent rotation of the ESP assembly10A within the tubing12. When engaged, the anchor48can also prevent the ESP assembly10A from moving axially within the tubing12. The actuator58may be electrically or hydraulically powered. Control and/or power of the actuator58can be done via the power cable20A. It is within the capabilities of those skilled in the art to develop and implement an actuator for use with the ESP system.

Further shown inFIG.3Bis the barrier34in a deployed mode with its outer surface in sealing contact with the inner surface of the tubing12. Because the barrier34extends radially outward from the pump inlet22A and fills the space between the inlet22A and tubing12, a pressure barrier is formed. In this example, the pressure barrier isolates discharged fluid flowing from ports26from produced fluid flowing into the pump inlet22A. Au example of expanding the barrier34A into its deployed configuration is shown in side partial sectional view InFIG. 4where illustrated in detail is an example embodiment of the anchoring and isolation portions of the ESP assembly10A ofFIG.3B. As depicted in the example ofFIG. 4, the upper end of the barrier34B is secured to the upper bracket36B, and the upper bracket36B is spaced radially outward from the pump inlet22B and axially away from lower bracket38B.Spacing the upper bracket36B radially outward defines a gap66between the upper bracket36B and pump inlet22B similar to the barrier34of Figures lA and1B. In an example, barrier34B fills with discharged fluid from the pump24A (FIG. 3B), as illustrated by arrows A making their way through the gap66. As such, pressure isolation can he achieved between the inlet and discharge of the pump24A while it is operational. Optionally, barrier34A can he made from a substantially solid elastomerie member that expands radially outward when axially compressed. Metal plates (not shown) may be included with barrier34A in one example embodiment where the plates can overlap to improve sealing. A portion of the plates can extrude outside the elastomer and engage the tubular, which can provide an anti-rotation force. In an alternate embodiment, a timer (not shown) is included with the ESP system10A for use in control of the system10A, embodiments include the timer being in communication with the controller45.

Further illustrated inFIG. 4is a spring68coiled around the pump inlet22B and between the upper and lower collars52B,54B. When the anchor48B is in the anchoring configuration ofFIG. 4, the spring68is in a compressed state, so that by retracting the actuator58upward and away from the upper collar52B, the compressed spring68can axially bias the upper collar52B away from the lower collar54B thereby drawing the landing pads56B radially inward and away from the tubing12. This unanchors the pumping assembly from within the tubing12and enables withdrawal of the ESP system10A, or redeployment of the ESP system10A at a different depth within the tubing12. In one optional embodiment, the lower collar54B is in selective contact with the upper bracket36B, so that when anchor48B is deployed, the upper bracket36B is urged downward causing the barrier34A to radially expand similar to a packer and create the sealing barrier.

The present invention described herein, therefore, is well adapted to carry out the objects and attain the ends and advantages mentioned, as well as others inherent therein. While a presently preferred embodiment of the invention has been given for purposes of disclosure, numerous changes exist in the details of procedures for accomplishing the desired results. For example, a locking mechanism can be included to lock the isolation device in place. Also, shear pins may optionally be included to allow unsetting of the isolation device when being pulled. These and other similar modifications will readily suggest themselves to those skilled in the art, and are intended to be encompassed within the spirit of the present invention disclosed herein and the scope of the appended claims.