US20160215575A1

US20160215575A1 - Rod Suspension System for Integrated Wellhead

Info

Publication number: US20160215575A1
Application number: US15/004,537
Authority: US
Inventors: Clark E. Robison; James S. Trapani; Benson Thomas; Kyle C. Brosch
Original assignee: Weatherford Technology Holdings LLC
Current assignee: Weatherford Technology Holdings LLC
Priority date: 2015-01-22
Filing date: 2016-01-22
Publication date: 2016-07-28
Also published as: WO2016118888A1; CA2974197A1; EP3247871A1

Abstract

An artificial lift system for a well having a wellhead reciprocates a rod string with an uphole pump unit at the wellhead to operate a downhole pump unit in the well and lift fluid in the well. A rod segment coupled to the rod string at the wellhead has first opposing surfaces facing in first opposing directions. Opposing catchers are movable laterally relative to the rod segment at the wellhead. Each of the catchers has a face with second opposing surfaces facing in second opposing directions opposite to the first opposing directions. The catchers moved in a first condition have the second opposing surfaces disengaged from the first opposing surfaces of the rod segment, but the catchers moved in a second condition have the second opposing surfaces engaged with the segment's first opposing surfaces to hold the rod string in place.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Prov. Appl. No. 62/106,569, filed 22 Jan. 2015, which is incorporated herein by reference.

BACKGROUND OF THE DISCLOSURE

Many hydrocarbon wells are unable to produce at commercially viable levels without assistance in lifting the formation fluids to the earth's surface. In some instances, high fluid viscosity inhibits fluid flow to the surface. More commonly, formation pressure is inadequate to drive fluids upward in the wellbore. In the case of deeper wells, extraordinary hydrostatic head acts downwardly against the formation and inhibits the unassisted flow of production fluid to the surface.
A common approach for urging production fluids to the surface uses a mechanically actuated, positive displacement pump. Reciprocal movement of a string of sucker rods induces reciprocal movement of the pump for lifting production fluid to the surface. For example, a reciprocating rod lift system S of the prior art is shown in FIG. 1 to produce production fluid from a wellbore B. As is typical, surface casing C hangs from the surface and has a liner casing L hung therefrom by a liner hanger H. Production fluid from the formation F outside cement CT can enter the liner L through perforations P. To convey the fluid, production tubing T extends from a wellhead W downhole, and a packer PK seals the annulus between the production tubing T and the liner L. At the surface, the wellhead W receives production fluid from the tubing T and diverts it to a flow line FL.
The production fluid may not produce naturally reach the surface so operators use the reciprocating rod lift system S to lift the fluid. The system S has a surface pumping unit SPU, a rod string RS, and a downhole pump unit DPU. Any number of surface pumping units SPU can be used, such as a pump jack shown, hydraulic unit, or the like. The surface pumping unit SPU reciprocates the rod string RS, and the reciprocating string RS operates the downhole pump unit DPU to lift produced fluid up the production tubing T to the wellhead W. Any number of downhole pump units DPU can be used, such as the rod pump shown having the barrel and plunger.
Whenever service is required on the reciprocating rod lift system S, some means of suspending the rod string RS at the wellhead W is required to facilitate any service operations that are required. Conventional wellheads W have seal rams to seal around the polished rod sections of the rod string RS, but there generally is not a way to suspend the rod string RS. This problem has been addressed by the so-called rod lock wellhead system described in U.S. Pat. No. 6,223,819 to Double-E Inc.
For example, FIG. 2 shows the prior art lock assembly 23 disclosed in U.S. Pat. No. 6,223,819. The lock assembly 23 is used on a wellhead 10, which has upper and lower bodies 11 and 12 secured together by nut-bolt assemblies 13. A bore 15 extends through the bodies 11, 12 for a sucker rod or string 20 to extend through the wellhead to a downhole pump (not shown).
The lock assembly 23 is mounted in the upper body 11 for supporting the rod string 20 and to prevent the rod string 20 from being accidentally released. The assembly 23 includes a support rod 24, an operator screw 25, and a support sleeve or nut 30. Shown in a locked or engaged position in FIG. 2, the assembly 23 locks the rod string 20 out of operation and supports the rod string 20 from the wellhead.
As shown in FIGS. 3A-3B, the support rod 24 is a cylindrical member with a keyway 31 formed in the first or outward end of the rod for coupling the operator screw 25 with the rod 24. The inward end of the support rod 24 has an open ended vertical 2-step slot 32. A lower slot portion 32 a is sized to fit around the rod string 20 below a coupling flange 33 on the rod string 20, and an upper larger slot portion 32 b serves as a locking slot sized to receive the coupling flange 33 on the rod string 20 for supporting the rod string 20.
The upper slot portion 32 b is formed with inward vertical curved surface portions 32 c and with vertical locking flanges 32 d, which are spaced apart laterally to accommodate the diameter of the rod string 20 below the rod string locking flange 33. The larger size of the upper slot portion 32 b relative to the lower slot portion 32 a provides a support shoulder surface 32 e.
The support rod 24 can be moved laterally to an engaged position only when the rod string 20 is lifted to an elevation at which the coupling flange 33 is above the support rod upper slot portion 32 b. When the support rod 24 is moved inwardly by the operator screw 25 to the engaged position, the rod string 20 may be lowered with the flange 33 on the rod string 20 moving downwardly entering the upper slot portion 32 b to rest on the shoulder surface 32 e. At this position, the curved slot surfaces 32 c fit inwardly or wrap somewhat around the rod flange 33 so that the vertical lock flanges 32 d prevent the support rod 24 from being moved laterally out of engagement with the rod string 20. The support rod 24 can be disengaged from the rod string 20 when the rod string 20 is lifted upwardly to a position at which the coupling flange 33 is not in the upper slot portion 32 b of the support rod 24.
As illustrated in FIG. 2, the operator screw 25 fits through and is threadingly engaged with a sleeve 30 so that rotation of the operator screw 25 in the sleeve 30 moves the support rod 24 inwardly to engage the rod string 20 end outwardly to disengage the support rod 24 from the rod string 20. The support rod 24 slides inwardly and outwardly in a lateral cylindrical bore 26 formed in the upper body 11 of the wellhead.
When it is necessary to perform services or remove components, the wellhead 10 can be shut in using other components (not shown). To then suspend the rod string 20 in the well from the wellhead 10, the rod string 20 is raised to an elevation at which the coupling flange 33 is above the intersection of bore 26 in the upper body 11 with the vertical bore 15 through the body. The operator screw 25 is rotated to drive the support rod 24 inwardly to the locked position shown in FIG. 2 at which the inward ends of the opposite sides of the rod 24 engage the inward end of the blind bore 26 so that the open inward end of the rod 24 is around the rod string 20 below the coupling flange 33. At this fully locked position of the support rod 24, the rod string 20 below the flange 33 is within slot 32 with the lower cylindrical surface portion 32 a of the slot engaging the rod string 20 below the flange 33 limiting the inward movement of the support rod 24. The rod string 20 is then lowered with the flange 33 entering the upper slot portion 32 b of the rod 24. The lower edge of the flange 33 engages the support shoulder 32 e of the support rod 24 at the lower end of the upper slot portion 32 b so that the lower end of the flange 33 rests on the support shoulder 32 e thereby suspending the rod string 20 in the well. With the rod string 20 locked at a suspended position in the wellhead 10, various procedures can be performed, such as closing blowout preventer ram assemblies (not shown) and the like.
As can be seen, the lock assembly 23 discussed above uses a support rod 24 with a shoulder 32 e to engage under a flange 33 on the rod string 20. In many reciprocating installations, this form of engagement as well as others used in the prior art may damage the sealing surface of the polished rod section, which will eventually damage the seals in a stuffing box or elsewhere on a wellhead.
The subject matter of the present disclosure is directed to overcoming, or at least reducing the effects of, one or more of the problems set forth above.

SUMMARY OF THE DISCLOSURE

According to the present disclosure, an apparatus is used with a wellhead having a downhole unit operated with a rod string extending downhole from an uphole unit at the wellhead. The apparatus comprises a rod segment and opposing catchers. The rod segment couples to the rod string and has first opposing surfaces facing in first opposing directions. The rod segment is movable in the wellhead. For a reciprocating system, the rod segment can be moved longitudinally in the wellhead as the uphole unit reciprocates the rod string to operate the downhole unit. For a rotary system, the rod segment can be rotatable in the wellhead as the uphole unit rotates the rod string to operate the downhole unit.
The opposing catchers are movably laterally in the wellhead relative to the rod segment. Each of the catchers has a face with second opposing surfaces facing in second opposing directions opposite to the first opposing directions. The catchers moved in a first condition in the wellhead have the second opposing surfaces of the faces disengaged from the first opposing surfaces of the rod segment. Alternatively, the catchers moved in a second condition in the wellhead have the second opposing surfaces of the face engaged with the first opposing surfaces of the rod segment.
In use, the second opposing surfaces of the face engaged with the first opposing surfaces of the rod segment restrain movement of the rod segment longitudinally in opposing directions. Likewise, the opposite catches in the engaged condition restrain movement of the rod segment laterally.
In one embodiment, the first opposing surfaces can comprise surfaces facing inward toward one another forming a plurality of troughs defined circumferentially about the rod segment. As a corollary, the second opposing surfaces can then comprise surfaces facing outward away from one another forming a plurality of teeth projecting from the face for mating in the troughs of the rod segment.
In another embodiment, the first opposing surfaces can comprise outer portions of a concavity defined circumferentially about the rod segment. To be complimentary, the second opposing surfaces can then comprise outer portions of a convexity extending from the face and positionable adjacent the concavity of the rod segment.
The rod segment can be separately coupleable to sections of a rod string. For example, a first end of the rod segment can be coupleable to a first section of the rod string, while a second end of the rod segment is coupleable to a second section of the rod string.
The apparatus can further comprise an actuator coupling to one of the catchers and operable to move the catcher between the engaged and disengaged conditions. For example, the actuator can comprise an arm coupling to the catcher and movable laterally relative to the rod segment. In turn, the catcher may define a slot, and the arm can comprise a key coupling with the slot.
According to the present disclosure, an apparatus is used with a wellhead having a downhole unit operated with a rod string extending downhole from an uphole unit at the wellhead. The apparatus comprises a component, a rod segment, and opposing catchers. The component is disposed on the wellhead. The component has an axial bore for passage of the rod string and has first cross-openings communicating with the axial bore. As before, the rod segment couples to the rod string and has first opposing surfaces facing inward toward one another.
Again, the rod segment is movable in the axial bore of the component. For a reciprocating system, for example, the rod segment can be moved longitudinally in the component as the uphole unit reciprocates the rod string to operate the downhole unit. For a rotary system, the rod segment can be rotatable in the component as the uphole unit rotates the rod string to operate the downhole unit.
The opposing catchers are movable laterally in the first cross-openings of the component relative to the rod segment. As before, each of the catchers has a face with second opposing surface facing outward from one another. The catchers moved in a first condition in the component have the second opposing surfaces disengaged from the first opposing surfaces of the rod segment. Alternatively, the catchers moved in a second condition in the component have the second opposing surfaces engaged with the first opposing surfaces of the rod segment.
The rod segment can comprise a polished section. The component can have second cross-openings communicating with the axial bore. In this instance, the apparatus can comprise rams movably laterally in the second cross-openings relative to the rod segment. The rams movable between engaged and disengaged conditions with the polished section of the rod segment. For its part, the component can comprise at least one flange disposed at one end thereof that is coupleable with a portion of the wellhead.
According to the present disclosure, an apparatus is used with a wellhead having a downhole unit operated with a rod string extending downhole from an uphole unit at the wellhead. The apparatus comprises a rod segment and opposing catchers. The rod segment couples to the rod string and has a first, downward-facing profile. The rod segment is movable axially in the wellhead.
The opposing catchers are movable laterally in the wellhead relative to the rod segment. A first of the catchers has a first forked support with a second, upward facing profile. The catchers moved in a first condition in the component has the second profile disengaged from the first profile of the rod segment. Alternatively, the catchers moved in a second condition in the component have the second profile engaged with the first profile of the rod segment.
A second of the opposing catchers can comprise a second forked support fitting under at least a portion of the first forked support when in the second condition. Alternatively, the rod segment can comprise a third, upward-facing profile. A second of the opposing catchers can comprise a second forked support with a fourth, downward facing profile for engagement with the third profile.
According to the present disclosure, an artificial lift system for a well comprises an uphole pump unit, a downhole pump unit, and an apparatus. The uphole pump unit at the well is operable to reciprocate a rod string in the well, and the downhole pump unit in the well is operable to lift fluid in the well in response to the reciprocation of the rod string. The apparatus can be similar to that disclosed above and can be disposed between the uphole and downhole pump units.
According to the present disclosure, methods are used with a wellhead having a downhole unit operated with a rod string extending downhole from an uphole unit at the wellhead. The methods include steps for engaging a rod segment with opposing catchers and retaining movement of the rod segment in the wellhead.
The foregoing summary is not intended to summarize each potential embodiment or every aspect of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a reciprocating rod lift system as background to the present disclosure.

FIG. 2 illustrates a portion of a wellhead having a lock assembly according to the prior art for supporting a rod string.

FIGS. 3A-3B illustrate a top view and a side cross-sectional view of a support rod for the lock assembly in FIG. 2.

FIGS. 4A-4B illustrate cross-sectional views of a wellhead component, revealing a first rod suspension system according to the present disclosure in disengaged and engaged conditions.

FIG. 5 illustrates a detailed view of the catchers and the rod segment of the first rod suspension system.

FIGS. 6A-6B illustrate cross-sectional views of a wellhead component, revealing a second rod suspension system according to the present disclosure in disengaged and engaged conditions.

FIGS. 7A-7B illustrate side and end views of the rod segment for the second rod suspension system of the present disclosure.

FIG. 8 illustrates a side view of the rod segment and the opposing rod catchers in an engaged condition.

FIGS. 9A-9D illustrate perspective, cross-section, top, and back views of the rod catcher for the second rod suspension system.

FIGS. 10A-10B illustrate cross-sectional views of a wellhead component, revealing a third rod suspension system according to the present disclosure in disengaged and engaged conditions.

FIGS. 11A-11B illustrate a forked catcher for the third rod suspension system in top and front views.

FIG. 11C illustrates a side view of the wellhead component with a cross-passage for the forked catcher.

FIGS. 12A-12B illustrate cross-sectional views of a wellhead component, revealing a fourth rod suspension system according to the present disclosure in disengaged and engaged conditions.

FIG. 13 schematically illustrates a reciprocating pump system at a wellhead having a rod suspension system according to the present disclosure.

FIG. 14 schematically illustrates a rotating pump system at a wellhead having a rod suspension system according to the present disclosure.

DETAILED DESCRIPTION OF THE DISCLOSURE

FIGS. 4A-4B illustrate cross-sectional views of a wellhead component 50, revealing a first rod suspension system 56A according to the present disclosure in disengaged and engaged conditions. Although not shown, the wellhead component 50 can be used as part of a wellhead having gate valves, tubing spools, casing hangers, etc. Additionally, any uphole unit, such as a pump jack, a hydraulic assembly, a rotary drive, or the like can sit on the wellhead component or elsewhere on the wellhead. Additionally, any downhole unit (not shown), such as a reciprocating plunger pump, a progressive cavity pump, or other downhole pump, can be disposed downhole in a borehole from the wellhead component 50. The uphole unit can operate the downhole unit using a rod string RS extending downhole from the wellhead, similar to a reciprocating rod lift system known in the art and described previously or similar to a rotary pump system known in the art.
The wellhead component 50 has an axial throughbore 52 for passage of the rod string RS, fluid, etc. First cross-openings 54 a communicate with the bore 52 toward the uphole flange 51 a of the component 50, and second cross-openings 54 b can also be provided and can communicate with the bore 52 toward the downhole flange Sib of the component 50.
The rod suspension system 56A includes a rod segment 60 and opposing catchers 70. The rod segment 60 couples to the rod string RS and can move longitudinally in the bore 52 of the wellhead component 50. For example, the rod segment 60 can be a pony rod placed at the top end of the rod string RS and beneath a polished rod of a surface pumping unit. The rod segment 60 includes a profiled section 62 a and can have a polished section 62 b. The rod segment 60 has a set length to insure the placement of the profile section 62 a is always in close proximity to the rod catchers 70.
The first cross-openings 54 a hold the opposing catchers 70, while the second cross-openings 54 b can hold sealing rams 90. The catchers 70 can move laterally in the first cross-openings 54 a of the component 50 relative to the rod segment 60. For example, a ram-type system having actuators (not shown) can be operated to engage the catchers 70 with the rod segment 60. The rams 90 can also move laterally in the second cross-openings 54 b of the component 50 relative to the rod segment 60 using a ram-type system having actuators (not shown).
As shown in FIG. 4A, the catchers 70 moved in a first condition (away from one another) in the wellhead component 50 are disengaged from the rod segment 60. As shown in FIG. 4B, however, the catchers 70 moved in a second condition (toward one another) in the wellhead component 50 can engage the rod segment 60 at the profiled section 62 a. When the weight of the rod string RS is slacked, the catchers 70 will then support all of the weight to suspend the rod string RS connected to the segment 60 so maintenance and other operations can be performed.
As shown in FIG. 4A, the catchers 70 are moved away from one another in the disengaged condition, which allows the rod segment 60 to pass longitudinally through the bore 52 of the wellhead component 50, such as when reciprocating during operation. As then shown in FIG. 4B, the catchers 70 can be moved toward one another to engage their faces 72 against the profiled section 62 b of the rod segment 60 to hold the rod string at the wellhead component 50 for maintenance or the like.
At least one or both catcher 70 can be moved by an actuator 80 a (only one shown) that couples to the catcher 70 and is operable to move the catcher 70 between the engaged and disengaged conditions. The actuator 80 a has an arm 82 coupling to the catcher 70 and movable laterally relative to the rod segment 60. In particular, a key 83 on the arm 82 can engage in a slot 73 in the back of the catcher 70. The arm can be moved in any conventional manner, such as screwing in or out.
In addition to the first cross-openings 54 a for the catchers 70, the wellhead component 50 can have the second cross-openings 54 b communicating with the bore 50. Rams 90 can be movable laterally in these second cross-openings 54 b of the component 50 relative to the rod segment 60. As shown in FIG. 4B, the rams 90 can be positioned below the catchers 70 and moved to engage their sealing faces 92 against the polished section 62 b of the rod segment 60. In this way, the sealing rams 90 can be closed around the polished section 62 b of the segment 60 to seal off fluid communication in the axial bore 52 and to insure the well pressure is isolated so the surface pumping unit can then be safely removed.
Another set of sealing rams 90 can be used either in another set of cross-openings in the same component 50 or used in another component of the wellhead. For example, the other set of rams 90 can be a set of sealing rams positioned above the catcher 70 to seal around an upper section of the rod segment 60 or around a polished rod of the rod string RS above the segment 60. Alternatively, the other set of rams 90 can be a set of blind rams positioned in a lowermost position away from the catchers 70, which can be in the upper-most position in the sequence rams. These and other configurations are possible and may have various benefits for operations.
The rams 90 can have faces 92 of known design, such as having an arrangement of rubber and steel for sealing. Overall during use, the sealing rams 90 can seal around a portion of the rod string RS in the bore 52, can seal around the polished section 62 b of the segment 60 when supported by the catchers 70, or can close off against one another for shutting the bore 52 in the absence of a rod string.
Further details of the rod suspension system 56A are shown in FIG. 5, which illustrates a detailed view of the rod segment 60 and the opposing catches 70. The rod segment 60 has a first end 61 a coupleable to a first section of the rod string (not shown). Similarly, the rod segment 60 has a second end 61 b coupleable to a second section of the rod string. As shown, the first and second ends 61 a-b can be box ends having internal threads to connect to ends of the rod string directly or with connectors, as the case may be. In other alternatives, one or both of the ends 61 a-b can be pin ends having external threads. Between the ends 61 a-b, the rod segment 60 has the first, profiled section 62 a and the second, polished section 62 b.
The faces 72 of the catchers 70 have outward opposing surfaces 74 a-b of one or more teeth 75. Complementary to this, the profiled section 62 a of the rod segment 60 has inward opposing surfaces 64 a-b of one or more troughs 65. In the current embodiment, the first opposing surfaces 64 a-b on the rod segment 60 form a plurality of the troughs 65 defined circumferentially about the rod segment 60, and the second opposing surfaces 74 a-b on the catchers 70 form a plurality of the teeth 75 projecting from the face 72.
As can be seen, the teeth 75 are configured to mate in the troughs 65 of the rod segment 60. In particular, the catchers 70 moved toward one another around the profiled section 62 a of the rod segment 60 engage their outward opposing surfaces 74 a-b against the inward opposing surfaces 64 a-b of the rod segment 60. This retrains movement of the rod segment 60 axially in opposing directions when supported by the catchers 70 in the component's bore 52, as discussed previously. In other words, the engagement of the catches 70 prevent the rod segment 60 from moving axially up or down in the bore 52. Moreover, the opposing catches 70 also retain the rod segment 60 laterally.
In the above embodiment, the first and second opposing surfaces 64 a-b, 74 a-b include mating troughs 65 and teeth 75 for axially restraining the rod segment 60. Other opposing surfaces can be used. For example, rather than having multiple sets of opposing surfaces 64 a-b along the profiled section 62 a, the rod segment 60 can have one set of outwardly opposing surfaces 64 a-b (i.e., in the form of one trough 65). By complement, the faces 72 of the catchers 70 can have one set of inward opposing surfaces 74 a-b (i.e., in the form of one tooth 75). These surfaces 64 a-b, 74 a-b can be rectilinear (i.e., square, trapezoidal, etc.) as shown or can have other shapes.
Another embodiment of a rod suspension system 56B shown with reference to FIGS. 6A to 8 has monolithic faces with opposing surfaces for the rod segment 60 and the catchers 70. More particularly, FIGS. 6A-6B illustrates cross-sectional views of a wellhead component 50, revealing the second rod suspension system 56B according to the present disclosure in disengaged and engaged conditions. Similar reference numbers are used for like components to other embodiments disclosed herein.
The rod segment 60 has a profiled section 62 a with a monolithic face, and the opposing catchers 70 are similarly configured with opposing surfaces having complementary monolithic faces 72. In particular, FIGS. 7A-7B illustrate side and end views of the rod segment 60 for this second rod suspension system of the present disclosure. Again, the rod segment 60 has ends 61 a-b coupleable to sections of the rod string (not shown). The profiled section 62 a of the rod segment 60 has inwardly opposing surfaces 67 a-b facing toward one another. The surfaces 67 a-b are defined by the outer portions of a concavity 66 formed circumferentially about the rod segment 60.
By contrast, FIGS. 9A-9D illustrate perspective, cross-section, top, and back views of a rod catcher 70 for the second rod suspension system. Complimentary to the surfaces 67 a-b of the rod segment 60, the face 72 of the catcher 70 has a convexity 76 extending therefrom and positionable adjacent the concavity 66 of the rod segment 60 for mating therewith. At its outer portions, the convexity 76 has outwardly opposing surfaces 77 a-b facing away from one another.
Engagement of the catchers 70 with the profiled section 62 a of the rod segment 60 can follow in a similar manner as described previously. For instance, FIG. 6A illustrates a side view of the rod segment 60 and opposing rod catchers 70 in a disengaged condition, and FIG. 6B as well as FIG. 8 illustrate side views of the rod segment 60 and opposing rod catchers 70 in an engaged condition.
As best shown in the detail of FIG. 8, the faces 72 of the catchers 70 have the outward opposing surfaces 77 a-b of the convexity 76. Complementary to this, the profiled section 62 a of the rod segment 60 has the inward opposing surfaces 67 a-b of the concavity 66. The catchers 70 moved toward one another around the profiled section 62 a of the rod segment 60 engage their outward opposing surfaces 77 a-b against the inward opposing surfaces 67 a-b of the rod segment 60. This retrains movement of the rod segment 60 longitudinally in opposing directions as well as laterally when supported by the catchers 70 in the component's bore 52, as discussed previously.
During operation as shown in FIG. 6A, for example, the catchers 70 are moved away from one another in a disengaged condition, which allows the rod segment 60 to pass longitudinally through the axial bore 52 of the wellhead component 50. As then shown in FIG. 6B, the catchers 70 can be moved toward one another to engage their faces 72 against the profiled section 62 b of the rod segment 60 to hold the rod segment 60 and coupled rod string RS at the wellhead component 50.
As before, one or both of catchers 70 can be moved by an actuator 80 a (only one shown) that couples to the catcher 70 and is operable to move the catcher 70 between the engaged and disengaged conditions. The actuator 80 a has an arm 82 coupling to the catcher 70 and movable laterally relative to the rod segment 60. In particular, a key 83 on the arm 82 can engage in a slot 73 in the back of the catcher 70.
In addition to the first cross-openings 54 a for the catchers 70, the wellhead component 50 can have the second cross-openings 54 b communicating with the bore 50. Rams 90 can be movable laterally in these second cross-openings 54 b of the component 50 relative to the rod segment 60. As shown in FIG. 6B, the rams 90 can be moved to engage their sealing faces 92 against the polished section 62 b of the rod segment 60 to seal off fluid communication in the axial bore 60.
FIGS. 10A-10B illustrate cross-sectional views of a wellhead component 50, revealing a third rod suspension system 56C according to the present disclosure in disengaged and engaged conditions. Similar components to other embodiments are given like reference numbers and are not described again.
In this system 56C, a first catcher 70 a has a forked support 75 a for supporting a profile 65 a on the rod segment 60, while a second catcher 70 b opposing the first catcher 70 a has a forked support or shelf 75 b for also supporting the profile 65 a on the rod segment 60. Both of the supports 75 a-b can engage at least a portion of the profile 65 a. As particularly shown herein, the second catcher's support 75 b acts as a shelf and fits under the forked support 75 a on the first catcher 70 a.
In this way, with the catchers 70 a-b retracted in the disengaged condition shown in FIG. 10A, the rod segment 60 can pass through the component's bore 52. When the catchers 70 a-b are extended to the engaged condition shown in FIG. 10B, the forked support 75 a of the first catcher 70 a can support the rod segment 60 and attached rod string RS by engaging the profile 65 a. The forked shelf 75 b of the second catcher 70 b can in turn support the first catcher's forked support 75 a. (Similar to other embodiments, the rod segment 60 can have a polished section 65 c for engagement by the rams 90.)
For reference, FIGS. 11A-11B illustrate an embodiment of the first forked catcher 70 a for the disclosed rod suspension system in top and front views. The forked support 75 a preferably has an angled surface or shoulder 77 that can match the profile (65 a) of the rod segment (60). For its part, the second forked catcher 70 b can have orthogonal shoulders for its shelf to rest against the underside of the first catcher's forked support 75 a.
To align and guide the forked catcher 70 a, tabs or guides 79 can extend from the sides. As shown in the side view of the wellhead component 50 in FIG. 11C, the cross-opening 54 a for the first forked catcher (70 a) can have side slots 59 in which the tabs or guides (79) fit.
In the previous embodiment, the second forked catcher 70 b fits under (at least partially) and supports the first forked catcher 70 a. As an alternative, FIGS. 12A-12B illustrate cross-sectional views of a wellhead component 50, revealing a fourth rod suspension system 56D according to the present disclosure in disengaged and engaged conditions. Similar components to other embodiments are given like reference numbers and are not described again.
In this system 56D, the first catcher 70 a has the forked support 75 a for engaging a first profile 65 a on the rod segment 60, while the second catcher 70 b opposing the first catcher 70 a also has a forked support 75 b for engaging a second, opposite profile 65 b on the rod segment 60. In this arrangement, the first forked support 75 a is upward-facing to engage the downward-facing first profile 65 a of the segment 60, and the second forked support 75 b is downward-facing to engage the upward-facing second profile 65 b of the segment 60.
In this way, with the catchers 70 a-b retracted in the disengaged condition shown in FIG. 12A, the rod segment 60 can pass through the component's bore 52. When the catchers 70 a-b are extended to the engaged condition shown in FIG. 12B, the forked supports 75 a-b of the first and second catcher 70 a-b can engage and support the rod segment 60 at both of the opposing profiles 65 a-b.
In embodiments of the rod suspension system 56A-D disclosed herein, the engagement of the faces 72, shoulders 77, and the like of the catchers 70 with the profiled section 62 a, profiles 65 a-b, and the like of the rod segment 60 suspends the rod string RS without damaging the outside surface of the rod segment 60 or rod string RS. The inward and outward opposing surfaces 74 a-b, shoulders 77, forked supports 75 a-b, and the like of the catchers 70 and the profiled section 62 a and profiles 65 a-b engage one another so that the catchers 70 hold the weight of the rod string RS as well as any downward load and any upward load that may be applied to the rod string as a function of the well pressure.
A number of variations can be used for the inward and outward opposing surfaces. As discussed above in FIGS. 4A-4B and 5, for example, the surfaces 74 a-b can use angled shoulder, although square shoulders could be used. Additionally, the surfaces 74 a-b can use a series of shoulders facing both directions. In this way, the one or more surfaces on the catchers 70 can be formed as a pin, tooth, convexity, etc. of a desired geometry that engages in a matching hole, trough, concavity, etc. as the one or more surfaces on the rod segment 60. Other arrangements can be used. In fact, the catchers 70 can intertwine with the rod segment 60 in any number of robust structures.
Although previous arrangements disclosed the opposing surfaces of the rod segment 60 facing inward toward one another and disclosed the opposing surfaces of the catchers 70 facing outward away from one another, an opposite arrangement can be used.
Although sealing rams 90 have been disclosed for use with the rod segment 60 as noted above, the engagement of the rod segment 60 and the catchers 70 may not only support the full weight of the rod string, but can also help seal off any pressure forces. Also as an alternative, any sealing rams can be used on other components of the wellhead to engage another polished section of the rod string RS so that the wellhead component 50 disclosed herein can be configured without the second cross-ports 54 b and the rod segment 60 can be configured without the specific polished section 62 b.
As has been disclosed herein, the wellhead component 50 of the present disclosure having the catchers 70 (with or without sealing rams 90) can be used on a Blowout Preventer (BOP) of a wellhead where multiple sealing rams are used in the BOP. The rod suspension catchers 70 can be positioned in any sequence in the BOP relative to the other rams. Preferably, the catchers 70 are either in a middle position or an upper position in the BOP. Although the catchers 70 are preferably not in a lowermost position in the BOP, they could be for a given the implementation.
For example, FIG. 13 schematically illustrates a pumping system 100A that can use a rod suspension system 56 according to the present disclosure. As shown here, the pumping system 100A can be a reciprocating type of system having a plunger pump for the downhole unit 108 and having a pump jack 106 or the like as a surface drive. A wellhead 120 has a Blowout Preventer (BOP) 110, a stuffing box 130, polished rod 102, and the like along with catchers 70 and rams 90 of a wellhead component 50 according to the present disclosure.
As shown here, the catchers 70 are preferably in an uppermost position in the BOP 110 because this facilitates the optimum placement of the rod segment 60 during operations. In particular, to suspend the rod string 106 during operations, the rod string 106 can be pulled to its uppermost position by either the pumping unit 104 (if present) at the surface or by a crane (not shown). When this is done, the profile 62 a on the rod segment 60 will be more readily situated in the correct position between the opposing catchers 70 in the wellhead component 50.
With the catchers 70 in the uppermost position, lower rams 90 a (in a dual ram configuration) or a middle ram 90 b (in a triple configuration) may include seals configured to seal around a polished section 62 b of the rod segment 60 or around a normal sucker rod of the rod string 106 and not necessarily a polished rod 102. In the triple BOP configuration, the lowermost rams 90 b will most likely always be a set of blind rams. In this way, should the rods 102, 106, and/or 60 come apart, the blind rams 90 b can be activated to seal off the well pressure in the BOP 110 without the need for a rod member to be positioned across the rams 90 b.
Furthermore, the polished rod sections 102 are optimally placed above the rod segment 60 because the stuffing box 130 normally used to seal against the polished rod 102 is above all of the rams 90 a-b in the BOP 110. This gives the operator the additional flexibility to suspend the rod string 106, seal off the well pressure, and then break the connection to the polished rods 102 above the rod segment 60 to replace the stuffing box seals or the like.
In one implementation, the rod segment 60 can be about 36-in in length and about 1.5-in in diameter. With such a length for the rod segment 60, it is possible for sealing rams 90 a configured to seal around the segment's polished rod section 62 b with a 1.5-in sealing dimension. However, other configurations are possible.
For instance, the rod segment 60 can be shorter (say 12-in in length). A changeover thread on the bottom of the segment 60 can be the size of the sucker rod of the rod string 106 used. In this case, the sealing rams (e.g., 90 a in FIG. 13) in the BOP 110 below the catchers 70 can be configured to instead seal around a portion of the sucker rod string 106 with an appropriate sealing dimension—instead of around the polished section 62 b of the rod segment 60. Being able to seal around the sucker rod string 106 can be beneficial when operators are changing polished rods 102 out. The shorter rod segment 60 can be fitted on the lower end of any length of upper polished rod 102, and a pony rod (not shown) for spacing of the sucker rod string 106 can extend downhole from the lower end of the rod segment 60. When the shorter rod segment 60 is lifted up and held by the catchers 70, the lower sealing rams 90 a on the BOP 110 can be closed on the sucker rod string 106 or the sucker rod pony used for spacing.
Because this rod suspension system 56 can include seal rams 90 a, the surface pumping unit 104 can be safely removed from the well to perform whatever service is required. The structure in the wellhead 120 can be designed with various configurations to distribute the loads between a key way, in interlocking shoulders between the catchers 70 and rod segments, or between a dual catcher system.
The rod suspension system 56 of the present disclosure can be used with other uphole and downhole units for other pumping assemblies, such as rotary pumping assemblies having a progressive cavity pump or the like. For example, FIG. 14 schematically illustrates a rotary pump assembly 100B having a rod suspension system 56 according to the present disclosure.
This rotary pump assembly 100B is a progressive cavity pumping system. As such, the assembly 100B includes a progressive cavity pump 140 as the downhole unit and has a rotary drive 150 as the uphole unit, which imparts rotation to the progressive cavity pump 140 via a rod string 106.
Downhole, the progressive cavity pump 140 installs below the wellhead 120 at a substantial depth (e.g., about 2000 m) in the wellbore. Typically, the pump 140 has a single helical-shaped rotor 142 that turns inside a double helical elastomer-lined stator 144. During operation, the stator 144 attached to production tubing string 14 remains stationary, and surface drive 150 coupled to rotor 142 by drive string 106 cause rotor 142 to turn eccentrically in stator 144. As a result, a series of sealed cavities form between stator 142 and rotor 144 and progress from the inlet end to the discharge end of pump 140, which produces a non-pulsating positive displacement flow.
At the surface, the surface drive 150 has a drive head 152 mounted above wellhead 120 and has an electric or hydraulic motor 154 coupled to the drive head 152 by a pulley/belt assembly or gear box 156. The drive head 150 typically includes a stuffing box (not shown), a clamp 158, and a polished rod 159. The stuffing box is used to seal the connection of drive head 150 to drive shaft 106, and the clamp 158 and polished rod 159 are used to transmit the rotation from the drive head 152 to the drive shaft 106.
To suspend the rod string 106 for maintenance or the like, a wellhead component 50 at the wellhead 120 has catchers 70 (and optionally rams 90). A rod segment 60 of the rod suspension system 56 is connected to the rod string 106 and is disposed in the wellhead component 50. The catchers 70 and the rams 90 can be configured respectively to engage the profiled section 62 a and the polished section 62 b of the rod segment 60 as before to suspend the rod string 106.
For such a rotating system, it may be advantageous to be able to react to torque in the rod string 106 and prevent rotation while gripping the rod string 106 to support its weight at the wellhead 120. Accordingly, the assembly 100B can include components and features to hold the rod string 106 and prevent it from rotating due to torque and the like. For example, back spin retarders, brakes, locking mechanisms, and other components know in the art can be used to prevent rotation of the rod string 106 when the rod string 106 is being supported by the rod suspension system 56. Many of these types of components are already used with rotary drives for rod strings and can be readily incorporated into the rod suspension system 56 of the present disclosure.
Moreover, should alignment be achievable between an orientation of the rod segment 60 and the catchers 70, then longitudinally arranged slots and profiles between the outside surface of the rod segment 60 and the inside surfaces of the catchers 70 can be used to prevent rotation of the rod segment 60 once aligned and engaged by the catchers 70. Although both longitudinal and rotational support could be provided by the same catcher 70, separate sets of catchers 70 (one set for longitudinal support and another set for rotational support) could preferably be used in the same or separate wellhead component 50.
The foregoing description of preferred and other embodiments is not intended to limit or restrict the scope or applicability of the inventive concepts conceived of by the Applicants. It will be appreciated with the benefit of the present disclosure that features described above in accordance with any embodiment or aspect of the disclosed subject matter can be utilized, either alone or in combination, with any other described feature, in any other embodiment or aspect of the disclosed subject matter.
In exchange for disclosing the inventive concepts contained herein, the Applicants desire all patent rights afforded by the appended claims. Therefore, it is intended that the appended claims include all modifications and alterations to the full extent that they come within the scope of the following claims or the equivalents thereof.

Claims

What is claimed is:

1. An apparatus for use at a wellhead of a well having a downhole unit operated with a rod string extending downhole from an uphole unit at the wellhead, the apparatus comprising:

a rod segment coupling to the rod string and having first opposing surfaces facing in first opposing directions, the rod segment movable in relation to the wellhead; and

opposing catchers movable laterally at the wellhead relative to the rod segment,

the opposing catchers each having a face with second opposing surfaces facing in second opposing directions opposite to the first opposing directions,

the opposing catchers moved in a first condition at the wellhead having the second opposing surfaces of the faces disengaged from the first opposing surfaces of the rod segment,

the opposing catchers moved in a second condition at the wellhead having the second opposing surfaces of the faces engaged with the first opposing surfaces of the rod segment.

2. The apparatus of claim 1, wherein the first opposing surfaces comprise first inward surfaces facing inward toward one another and forming a plurality of troughs defined circumferentially about the rod segment.

3. The apparatus of claim 2, wherein the second opposing surfaces comprise second outward surfaces facing outward away from one another and forming a plurality of teeth projecting from the face for mating in the troughs of the rod segment.

4. The apparatus of claim 1, wherein the first opposing surfaces comprise first outer portions of a concavity defined circumferentially about the rod segment.

5. The apparatus of claim 4, wherein the second opposing surfaces comprise second outer portions of a convexity extending from the face and positionable adjacent the concavity of the rod segment.

6. The apparatus of claim 1, wherein the rod segment comprises a first end coupleable to a first section of the rod string and comprises a second end coupleable to a second section of the rod string.

7. The apparatus of claim 1, further comprising an actuator coupling to at least one of the opposing catchers and operable to move the at least one opposing catcher between the first and second conditions.

8. The apparatus of claim 7, wherein the actuator comprises an arm coupling to the at least one opposing catcher and movable laterally relative to the rod segment.

9. The apparatus of claim 8, wherein the at least one opposing catcher defines a slot, and wherein the arm comprises a key coupling with the slot.

10. The apparatus of claim 1, wherein the second opposing surfaces of the face engaged with the first opposing surfaces of the rod segment restrain movement of the rod segment longitudinally in opposing directions.

11. The apparatus of claim 1, wherein the opposing catchers in the second condition restrain movement of the rod segment laterally.

12. The apparatus of claim 1, further comprising a component disposed at the wellhead, the component having a throughbore for passage of the rod segment and having first cross-openings for the opposing catchers communicating with the throughbore.

13. The apparatus of claim 12, wherein the rod segment comprises a polished section.

14. The apparatus of claim 13, wherein the component comprises opposing rams movable laterally in second cross-openings of the component relative to the rod segment, the opposing rams movable between sealed and unsealed conditions with the polished section of the rod segment.

15. The apparatus of claim 12, wherein the component comprises at least one flange disposed at one end thereof and coupleable with a portion of the wellhead.

16. An artificial lift system for a well having a wellhead, the system comprising:

a rod string;

an uphole unit at the wellhead operable to move the rod string in the well;

a downhole unit in the well operable to lift fluid in the well in response to the movement of the rod string; and

a rod segment coupled to the rod string at the wellhead and having first opposing surfaces facing in first opposing directions; and

opposing catchers movable laterally relative to the rod segment at the wellhead,

17. The system of claim 16, comprising a component disposed at the wellhead, the component having a throughbore for passage of the rod segment and having first cross-openings communicating with the throughbore for the opposing catchers.

18. The system of claim 17, wherein the rod segment comprises a polished section; and wherein the component comprises rams movable laterally in a second cross-openings relative to the rod segment, the rams movable between sealed and unsealed conditions with the polished section of the rod segment.

19. The system of claim 16, wherein the uphole unit at the wellhead is operable to reciprocate the rod string longitudinally in the well; and wherein the downhole unit in the well is operable to lift fluid in the well in response to the reciprocation of the rod string.

20. The system of claim 19, wherein the downhole unit comprises a reciprocating rod pump disposed in the well; and wherein the uphole unit comprises a pump jack or a hydraulic jack.

21. The system of claim 16, wherein the uphole unit at the wellhead is operable to rotate the rod string in the well; and wherein the downhole unit in the well is operable to lift fluid in the well in response to the rotation of the rod string.

22. The system of claim 21, wherein the downhole unit comprises a progressive cavity pump having a stator with a rotor rotatable therein by the rotation of the rod string; and wherein the uphole unit comprises a rotary drive imparting the rotation to the rod string.

23. An apparatus for use at a wellhead having a downhole unit operated with a rod string extending downhole from an uphole unit at the wellhead, the apparatus comprising:

a rod segment coupling to the rod string and having a downward-facing profile, the rod segment movable longitudinally relative to the wellhead; and

opposing catchers movable laterally in the wellhead relative to the rod segment, the catchers each having a forked support with an upward-facing profile, the catchers moved in a first condition having the upward-facing profiles disengaged from the downward-facing profile of the rod segment, the catchers moved in a second condition having the upward-facing profiles supporting with the downward-facing profile of the rod segment.

24. The apparatus of claim 23, wherein the forked support of a first of the opposing catchers when in the second condition fits under at least a portion of the forked support of a second of the opposing catchers.

25. An apparatus for use at a wellhead having a downhole unit operated with a rod string extending downhole from an uphole unit at the wellhead, the apparatus comprising:

a rod segment coupling to the rod string and having a first downward-facing profile and first upward-facing profile, the rod segment movable longitudinally relative to the wellhead; and

opposing catchers movable laterally in the wellhead relative to the rod segment, a first of the opposing catchers having a first forked support with a second upward-facing profile, a second of the opposing catchers having a second forked support with a second downward-facing profile, the opposing catchers moved in a first condition having the second profiles disengaged from the first profiles of the rod segment, the opposing catchers moved in a second condition having the second profiles engaged with the first profiles of the rod segment.