CONTINUOUS ROD PUMP DRIVE SYSTEM

Abstract

In a downhole rod-driven pump, continuous rod is used to drive the pump. The continuous rod is connected directly to the drive eliminating the need for a polish rod and an uphole coupling. A coupling is used to connect the continuous rod to the pump reducing restrictions in the production annulus and wear on the production tubing. Further, clean out tubing can be inserted into the production tubing beside the continuous rod and can extend therein to the pump without restriction. When the coupling is a threaded coupling, the continuous rod can be rotated in an appropriate direction to release the continuous rod from the pump when the pump is stuck. When the coupling is a shear coupling, the shear coupling can be sheared for releasing the pump from the continuous rod. When the pump is a progressing cavity pump and the coupling is a shear coupling, the continuous rod can be reverse rotated for changing the direction of pumping and if the rotor thereafter remains stuck, the shear coupling can be sheared.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a regular application claiming priority of U.S. provisional application 61/330,095 filed Apr. 30, 2010, the entirety of which is incorporated herein by reference.

FIELD OF THE INVENTION

Embodiments of the invention relate to systems and apparatus for driving a downhole pump using continuous rod, and more particularly, for eliminating a polish rod and couplings thereto and couplings along a length of the continuous rod until at least a top of the pump for reducing wear on production tubing through which the continuous rod extends and for providing annular space thereabout for insertion of at least cleanout tubing.

BACKGROUND OF THE INVENTION

One of skill in the art will appreciate that there are many types of pumps which are actuated by rotation or reciprocation of a rod string. Examples of such pumps, used for pumping fluids in a wellbore, are plunger pumps (reciprocating) and progressing cavity pumps (rotary).

Plunger pumps typically comprise pistons or plungers which are reciprocated for pumping fluids through production tubing to surface. The pump typically comprises a standing valve, which opens on an upstroke for drawing fluids into the pump and closes on a downstroke, and a travelling valve, which is closed on the upstroke and which opens on the downstroke, for forcing fluid out of the pump and into the production string.

Progressing cavity pumps (PC pumps) comprise a stator and a rotor, the rotor being rotated within the stator for pumping fluids therethrough. The stator is generally connected at the bottom of production tubing.

The driven components, typically the plunger of the reciprocating pump and the rotor of the PC pump, are driven using a string of rods which extend axially through the production tubing from surface to the pump. The production tubing is hung from a tubing hanger in a wellhead at surface and extends downhole in a cased wellbore. A production annulus is formed between the rod string and the production tubing. Produced fluids, from the pump, flow up the production annulus to surface. The rod string comprises a polish rod at the wellhead which is coupled at a downhole end to a plurality of sucker rods therebelow, the sucker rods being connected end-to-end by couplings for forming the rod string. Typically each of the plurality of sucker rods is typically about 25 to 30 feet in length. There can be hundreds of such connections along the length of the rod string.

As one of skill in the art will appreciate, each of the couplings, being of larger diameter than the sucker rods, creates a localized restriction in the production annulus.

At a minimum, it is known to connect an uphole end of the rod string to the polish rod using a coupling and to connect a downhole end of the rod string to the pump, such as to the rotor, using a coupling The couplings have an outer diameter which is larger than the outer diameter of the sucker rod string. For example, in the case of a sucker rod having a 1″ pin end, the couplings have an outer diameter of 2- 3/16″ or in the case where the couplings are designed for slim hole, the couplings have an outer diameter of about 2″. In the case of a sucker rod having a ⅞″ pin end, the couplings have an outer diameter of 1- 13/16″ or in the case where the couplings are designed for slim hole, the couplings have an outer diameter of about 1-⅝″.

Alternatively, the rod string is a continuous rod string, such as PRO-ROD® available from C-Tech Oilwell Technologies Inc. of Edmonton, Alberta, Canada. Use of continuous rod permits couplings to be eliminated along a length of the rod string, however the continuous rod requires at least a coupling at the polish rod and at the connection to the rotor.

The polish rod extends through a rotary drive and a rotary seal at the wellhead, typically called a stuffing box, and for a short distance into the production tubing, forming a production annulus therebetween. The polish rod is generally a rod of known and consistent dimensions for unrestricted and sealable movement through the stuffing box and through the rotary drive, as necessary.

In the case of a PC pump, some axial movement of the polish rod, and the rod string connected thereto is required to enable manipulation of the rotor during setting and removal of the rotor from the stator. Thus, the polish rod must have a length sufficient to enable manipulation of the rotor from the stator, typically from about 25 to about 36 feet long. Further, so as to properly locate the rotor relative to the stator, one or more short pony rods are connected and coupled between the polish rod and the rod string to ensure that the polish rod is properly located through the wellhead and wellhead drive. In the case of a reciproxating pump, the rod string must have sufficient length to ensure that the rod string, when connected between the pump jack and the pump provides sufficient length to ensure a full stroke of the pump while sealing at the stuffing box. As noted above, each coupling forms a localized restriction in the production annulus.

Additionally, a shear coupling is normally provided between the rod string and pump to ensure that the rod string can be released from the pump in a worst case scenario where the pump seizes.

The two or more couplings, spaced apart between the polish rod and the pump, reciprocate or rotate with the rod string. IN the case of a PC pump, the couplings remain at substantially the same elevation in the well throughout their service. As the couplings are localized diameter changes along the rod string, the couplings act as point loads on the wall of the production tubing and can cause significant wear thereto. Eventually, the point loading of the production tubing may result in a wearing through of the tubing causing leaks therein and a loss of production.

Additionally problematic is the reduction in the production annulus at each of the couplings. In instances where the pump becomes blocked with particulates, such as sand, it is known to lower a small diameter cleanout tubing string, generally coiled tubing, through the production annulus to the pump so as to deliver washing fluids thereto to clear sand. Each coupling, including the uphole coupling between the polish rod and the rod string, is a potential obstruction to the bypass of the cleanout tubing through the production annulus. It is known to pass the cleanout tubing into the production tubing, through ports in the wellhead such as taught in Canadian Patent 2,310,236 to Titus Tools Inc., Lloydminster, Alberta, Canada.

In the case of a PC pump, due to the threaded coupling connections, typically right hand threads, the direction of rotation of the rotor cannot be changed because, if reversed, the threading, at one or more of the couplings, can unthread risking loss of the rod string in the production tubing. Even in the case where a continuous rod is used, reverse rotation will result in an unthreading of the uphole coupling at the polish rod resulting in dropping of the rod string.

Therefore there is a need for a system which avoids these limitations and, in particular, which can minimize wear of the production tubing, rod and rod couplings and which can enable the passage of a cleanout tubing therealong.

SUMMARY OF THE INVENTION

Continuous rod is connected directly to a drive or through a stuffing box eliminating the need for the polish rod and an uphole coupling. As a result, the continuous rod utilizes one or more couplings at the downhole end of the continuous rod for connection to the pump. Localized wearing of the production tubing is minimized as there is only one location at which wear might occur. Further, the production annulus remains unrestricted from the wellhead to the top of the pump permitting cleanout tubing and the like to pass therethrough to the pump.

In a broad aspect, a method is provided for installing and driving a driven component of a rod-driven pump, the pump being fluidly connected at a bottom of a string of production tubing fluidly connected to a wellhead at surface. The method comprises providing a continuous rod and coupling a downhole end of the continuous rod to an uphole end of the driven component. The continuous rod and driven component are run downhole through a bore of the production tubing ensuring the continuous rod is of sufficient length to be operatively connected to the pump in the wellbore and drivingly secured to a drive at surface. The continuous rod is driveably secured the to the drive at surface, wherein the continuous rod is driven by the drive for pumping produced fluids to surface through the bore of the production tubing.

In the case of a progressing cavity pump the driven component is a rotor. In the case of a reciprocating pump the driven component is a plunger.

In another broad aspect, a method for servicing a rod-driven pump fluidly connected to a bore of a production tubing in a wellbore comprises: driveably connecting an uphole end of a continuous rod directly to a drive at surface, the continuous rod extending through the bore of the production tubing from the drive to the pump. A coupling is provided for driveably connecting between a downhole end of the continuous rod and the pump. A cleanout tubing string is inserted through the bore of the production tubing in a production annulus formed between the continuous rod and the production tubing, the cleanout tubing string passing within the production annulus, substantially unrestricted by the continuous rod therein, to the coupling at the downhole end of the continuous rod. Cleanout fluids are provided through the cleanout tubing string.

In another broad aspect, a rod string for driving a pump in a wellbore comprises a continuous rod having an uphole end for drivingly connecting to a drive at surface and a downhole end for connection to the pump; and a coupling for connecting between the downhole end of the continuous rod and the pump.

In yet another broad aspect, a rod-driven pumping system comprises a drive positioned at surface, a continuous rod driveably connected to the drive and extending downhole through a bore of a production tubing to a pump, forming a production annulus therebetween; and a coupling connecting between the continuous rod and the pump, the production annulus having a maximized pass-by clearance along a length of the continuous rod from the wellhead to the coupling at the pump and being sufficient to permit a cleanout tubing to pass substantially unrestricted therethrough.

In an embodiment, the coupling is a threaded coupling. In the case of a PC pump, should the rotor become stuck in the stator, such as due to particulate deposition therein, the direction of rotation can be reversed for unthreading the threaded coupling at the rotor, freeing the continuous rod from the rotor. In the case of the reciprocating pump, the rod can be rotated in an appropriate direction for unthreading the threaded coupling at the pump for freeing the continuous rod from the reciprocating pump.

In an embodiment, the coupling is a shear coupling. Advantageously, in the case of a PC pump, as the shear coupling is not a threaded coupling, the direction of rotation of the continuous rod and the rotor can be reversed for pumping the particulates downhole for freeing the rotor without risk of separating the continuous rod from the rotor. Thereafter, the direction of rotation can be reversed again for pumping to surface.

In the case of both a PC pump and a reciprocating pump, should cleaning operations be unsuccessful, an axial shearing of the shear coupling can be performed for releasing the continuous rod from the pump.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial longitudinal sectional view of prior art couplings connecting adjacent sucker rods, for forming a rod string in production tubing;

FIG. 2A is an elevation view of a wellhead installation and PC pump showing a cross-section of a wellbore portion, the installation implementing an embodiment of the invention in a production mode;

FIG. 2B is a partial longitudinal sectional view according to FIG. 2A, illustrating a continuous rod connected to an uphole end of a pump rotor therein;

FIG. 2C is a cross-sectional view according to FIG. 2B illustrating a production annulus about the continuous rod in production tubing hung in a wellbore casing;

FIG. 2D is an elevation view of a wellhead installation and reciprocating pump showing a cross-section of a wellbore portion, the installation implementing an embodiment of the invention in a production mode;

FIG. 3A is a partial longitudinal sectional view of one embodiment of a threaded coupling for connecting between continuous rod and a pump rotor;

FIG. 3B is a partial longitudinal sectional view of one embodiment of a shear coupling for connecting between continuous rod and a pump rotor;

FIG. 4A is a longitudinal sectional view of a drive head of the wellhead installation of FIG. 2A, the continuous rod being operatively connected to a drive shaft above the production tubing;

FIG. 4B is a partial elevation view of a polished rod liner installed on the continuous rod;

FIG. 5A is an elevation view of a wellhead installation and PC pump, the installation implementing a Y-access service adapter for a running a service coil tubing into the production annulus in a service mode;

FIG. 5B is an elevation view of a wellhead installation and PC pump, the installation implementing an integrated Y-access service adapter installed below a wellhead drive for a running a service coil tubing into the production annulus in a service mode;

FIG. 5C is a partial longitudinal sectional view according to FIGS. 5A and 5B illustrating the continuous rod connected to an uphole end of the pump and the service coil tubing positioned in the production annulus thereabout;

FIG. 5D is a cross-sectional view according to FIG. 5C illustrating the service coil tubing in the production annulus;

FIG. 6 is a side elevation, cross-sectional view of an embodiment of a rod lock-out clamp for engaging the continuous rod;

FIG. 7 is a plan view of the rod lock-out clamp according to FIG. 6;

FIG. 8 is a side elevational, cross-sectional view of a blowout preventer having an integrated rod lock-out clamp for engaging the continuous rod;

FIG. 9 is a plan view of the integrated rod lock-out clamp of FIG. 8; and

FIG. 10A is a plan view of a piston of a rod-lock clamp illustrating a gripping profile suitable for use with continuous rod according to an embodiment of the invention; and

FIG. 10B is a detailed plan view of the gripping profile according to

FIG. 10A.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Having reference to FIG. 1, prior art couplings 10 are used for connecting between adjacent lengths of sucker rod 12 for forming a rod string 14. As can be seen, a diameter of the couplings 10 is greater than a diameter of the sucker rods 12 such that when the rod string 14 is positioned in a bore 15 of a string of production tubing 16, a plurality of rod-to-rod couplings create localized restrictions in a production annulus 18 between each coupling 10 along a length of the rod string 14 and the production tubing 16.

Embodiments of the invention can be used to drive rotary driven pumps or reciprocating pumps. In the case of rotary pumps, such as a progressing cavity pump (PC pump), the rod string 14 is rotated by a rotary drive at surface. In the case of reciprocating pumps, such as a plunger pump, the rod string 14 is reciprocated, such as by a pump jack at surface.

As shown in FIGS. 2A-2D, continuous rod 30 is utilized as the rod string 14 to replace the prior art lengths of sucker rod string 12, eliminating the need for the polish rod and the prior art plurality of rod-to-rod couplings 10 therealong. Instead, a continuous rod 30 extends from a drive D at surface to the pump P. A coupling 10 is used to couple the continuous rod 30 to the pump P at a downhole end 38 of the continuous rod 30. The continuous rod 30 is connected to a driven component of the pump P. As will be appreciated by one of skill in the art, while the coupling 10 is referred to herein in the singular, one or more couplings 10 may be used adjacent the downhole end 38 of the continuous rod 30 leaving the production annulus 18 substantially unobstructed therealong.

As shown in FIGS. 2A-2C, in the case of a PC pump P, a stator 20 is fluidly connected to the production tubing 16 in a wellbore 22. A rotor 24 is installed within the stator 20. According to embodiments of the invention, the continuous rod 30 extends from a drive head 26 installed on a wellhead 28 at surface to the rotor 24, which is the driven component. The coupling 10 is used to couple the continuous rod 30 to the rotor 24.

Having reference to FIG. 2D, in the case of a reciprocating pump P, the continuous rod 30 extends from a pumpjack drive D, through a stuffing box S which is fluidly connected to the wellhead 28 at surface to a driven component of the reciprocating pump P, typically a plunger T containing a travelling valve.

FIGS. 3A and 3B illustrate embodiments of couplings 10 which may be used to connect between the continuous rod 30 and the rotor 24.

In embodiments of the invention, the continuous rod 30 is driveably connected directly to the drive D, as will be discussed in greater detail below, eliminating the need for a conventional polish rod and eliminating the need for a prior art uphole coupling.

Further, in the case of a PC pump P, a plurality of pony rods and couplings 10, as required in the prior art to permit manipulation of the rotor 24 for installing in the stator 20, are not required as the continuous rod 30 has sufficient length to permit the rotor 24 to be raised and lowered for installation into the stator 20 in a PC pump P Only after installation of the rotor 24 into the stator 20 is the continuous rod 30 cut above the drive head 26.

In the case of a reciprocating pump P, the continuous rod 30 has sufficient length to permit connection between the pumpjack D and the plunger T for permitting a full stroke of the pump before the continuous rod 30 is connected to the pumpjack and is cut.

Advantageously, the continuous rod 30 and production tubing 16 diameters can be optimized for further benefits as described below.

In greater detail, and with reference to FIGS. 2A and 4A, for use with a PC pump P, the continuous rod 30, extends from the drive head 26 and through a wellhead 28 at surface, to the rotor 24 positioned in the stator 20 downhole. As shown in FIG. 4A, in an embodiment, the continuous rod 30 is driveably connected directly to the drive head 26, such as by extending through a hollow drive shaft 32 of the drive head 26, thereby eliminating the conventional polish rod. A variety of different sealing arrangements are known at the drive head 26, such as those avoiding a dynamic seal to the continuous rod 30.

The continuous rod 30 is coupled to the rotor 24 using a coupling 10, such as shown in FIG. 3A or 3B. The continuous rod 30 and the rotor 24 are run downhole through a bore in the production tubing 16 until the rotor 24 is inserted through the stator 20 to a tag pin or bar therebelow (not shown). The continuous rod 30 is lifted to properly locate the rotor 24 in the stator 20 after which the continuous rod 30 is driveably secured, such as by clamping, and cut to length above the drive head 26. Co-rotation of the drive shaft 32, the continuous rod 30 and the rotor 24 in a first, pumping direction, results in pumping of produced fluid through the production tubing 16 to surface.

In one embodiment, prior to installation of the drive head 26, the continuous rod 30 is coupled to the rotor 24 using the coupling 10 and is run into the production tubing 16. Once the rotor 24 is manipulated into the stator 20, the continuous rod 30 is locked to the wellhead 27, such as by a ram BOP therein. The continuous rod 30 is then cut to a length calculated based upon the length required to pass through the drive head 26, once installed on the wellhead, and to extend thereabove. The drive head 26 is then mounted to the wellhead 27 with the continuous rod 30 passing through the hollow drive shaft 32 and the continuous rod 30 is driveably secured, such as by clamping, above the drive head 26 for co-rotation with the drive shaft 32.

Having reference again to FIGS. 2D and 4B, in the case of a reciprocating pump P, the continuous rod 30 is coupled to the driven component of the reciprocating pump P, which is typically lowered through the production tubing using the continuous rod 30. Once the reciprocating pump P is positioned in the wellbore, the continuous rod 30 is cut to a sufficient length to pass through the wellhead components 28 and the stuffing box S and extend to the bridle 60 of the pumpjack D when the pumpjack D is at the top of the pump stroke. Once cut, a polished rod liner 70 and stuffing box S are typically lowered over the continuous rod 30 and the polished rod liner 70 is secured to the continuous rod 30. The continuous rod 30 is then typically connected to the bridle 60. As with the drive head 26 for the PC pump, a variety of different sealing arrangements are known at the stuffing box S, such as those avoiding a dynamic seal to the continuous rod 30. One such sealing arrangement comprises static seals which seal to the continuous rod and dynamic seals which seal to the polished rod liner 70 in the stuffing box S.

In an embodiment, having reference to FIG. 2B, a connection between the continuous rod 30 and the driven component of the pump P can comprise a short length or interface of sucker rod 34, such as about 2 feet in length. While shown and described in the context of a PC pump P, the interface of sucker rod 34 can also be used to connect between the continuous rod 30 and the driven component of a reciprocating pump. The sucker rod interface 34 is truncated at an uphole end 36 and is joined, such as by butt-welding directly to a downhole end 38 of the continuous rod 30. A downhole end 40 of the interface 34 comprises conventional rod male threading.

Further, in an embodiment, the coupling 10 is a conventional threaded coupling (FIG. 3A), which is threaded between the downhole end 40 of the interface 34 and an uphole threaded end 42 of the driven component. Using this embodiment, a conventional shear coupling 10 is not required to enable retrieval of the continuous rod 30 upon some failure, such as sanding-in of the rotor 24 in the stator 20 or blockage of the travelling valve T. Unlike a rod string 14 comprising a plurality of threaded sucker rod 12 lengths, the entirety of the continuous rod 30 can be reverse-rotated to predictably unthread only the threaded coupling 10 from the rotor 24. Thus, the rod string 14 cannot be lost and retrieval is easily available in cases where the pump P is stuck.

In an embodiment, the coupling 10 is a shear coupling, such as shown in FIG. 3B, which can transmit driving torque yet is susceptible to axial shearing. IN the case of a PC pump, connecting the continuous rod 30 to the rotor 24 with a driveable coupling 10 which enables bi-direction co-rotation, when the rotor 24 is stuck in the stator 20, generally as a result of sand or other particulates, the continuous rod 30 and rotor 24 can be reverse co-rotated to attempt to pump the particulates downhole into the formation for freeing the rotor 24. Thereafter, rotation can be returned to the first direction for pumping produced fluid to surface. Should efforts to free the rotor 24 fail, axial shearing of the shear coupling 10 is used to release the continuous rod 30 from the rotor 24. Similarly, in the case of a reciprocating pump, axial shearing of the shear coupling 10 is used to release the continuous rod 30 from the pump P.

Having reference to FIG. 4B, in the case of both rotary and reciprocating pumps P, a polished rod liner 70 may be installed over the continuous rod 30 for providing a larger diameter or improved surface for sealing, such as in the drive head 26 or the stuffing box S, to prevent the leakage of well fluid from around the continuous rod 30 at surface. Further, the polished rod liner 70 provides better bearing support and a smoother surface for sealing.

In a production mode, through the elimination of couplings 10 along a length of the continuous rod 30, the production annulus 18 is freed of restrictions. Further, one can implement production tubing 16 having a smaller bore 15 and still maximize a pass-by clearance in the production annulus 18 sufficient to permit passage of at least another small diameter tubing 50 thereby. For example, where 3-½″ production tubing would normally be used with conventional rod string 14, the use of 1″ continuous rod 30 without rod-to-rod couplings could instead enable use of 2-⅞″ production tubing 16. The smaller diameter production tubing 16 is less expensive and also increases the “rise velocity” of produced fluids for retention of suspended solids therein. With ⅞″ continuous rod 30, one might reduce the production tubing 16 further, to 2-⅜″ for example. Smaller production tubing 16 can further have the advantage of enabling re-commissioning of wells having damaged casing in which 3-½″ production tubing 16 can no longer be run downhole through the damaged area.

In embodiments, the smaller diameter tubing or cleanout string 50 is inserted into the bore 15 of the production tubing 16. The cleanout string 50 can be inserted through a stuffing box mounted to the well after removal of the drive equipment D or through service ports 52 provided in the wellhead 28.

Having reference to FIGS. 5A-5D, wellhead installations 28, fluidly connected to the production tubing 16, can comprise the service ports 52, such as Y-access service adapters (FIGS. 5A and 5B) or integrated Y-access service adapters installed below the drive head 26 (FIGS. 5C and 5D) to provide access to the production annulus 18. PC pumps may require servicing, such as cleaning out by flowing cleanout fluids therethrough. As a result of maximizing the pass-by clearance in the production annulus 18, the smaller diameter tubing 50, such as coiled tubing, can be passed through the service ports 52 and into the production annulus 18. Passage of the coiled tubing 50 is substantially unrestricted within the production annulus 18 until the coiled tubing 50 reaches the coupling 10 adjacent the uphole end 42 of the rotor 24. The coiled tubing 50 is inserted into the production 18 annulus through the variety of service ports 52 in the wellhead 28 and is lowered therein adjacent the uphole end 42 of the rotor 24 after which clean out fluids are provided therethrough.

Rod lock-out clamps, in most cases include BOP seals for sealing the well from release of well fluids and gases as taught in Applicant's issued Canadian patent 2,349,988, the entirety of which is incorporated herein by reference, are known for gripping a polished rod in a conventionally-driven pump installation. Relevant aspects from Canadian Patent 2,349,988 have been extracted and applied as follows.

Having references to FIGS. 6-9 and in embodiments of the invention, such rod lock-out clamps 160,180 may be used to grip the continuous rod 30 for temporarily suspending the continuous rod 30 in the wellbore and spacing out the pump P connected thereto during installation or servicing of the pump and drive components or during connection of drive and other wellhead components thereto.

The rod lockout clamp 160, 180 generally comprises a clamp body having a bore 164 formed therethrough for receiving the continuous rod 30. clamp members 182, such as two opposing radial pistons, for gripping the continuous rod 30 in the bore 164 and manipulating means 184, such as bolts, for moving the clamp members 182 into gripping engagement with the continuous rod 30.

As shown in FIGS. 6 and 7, it may be preferable not to restrict the diameter through the bore 164 so that the continuous rod 30 can be pulled through the clamp 160. The continuous rod 30 is gripped by arcuate recesses 186, which are prefereably made undersize relative to the continuous rod 30 to enhance gripping force. The pistons 182 further include O-rings 223 to provide a better seal in the bore 164.

Having reference to FIGS. 8 and 9, where the clamp 180 is integrated with a blow out preventer, the pistons 182 are made substantially of metal so as to allow the pistons 182 to be forced into engagement with the continuous rod 30 to prevent movement of the continuous rod 30 therein. An inner end of the pistons 182 is formed with an arcuate recess 186 with a curvature corresponding substantially to that of the continuous rod 30. Enhanced gripping force is achieved if the arcuate recess diameter is undersized relative to the continuous rod 30. A narrow elastomeric seal 188 is provided which runs across the vertical flat surface of the piston 182, along the arcuate recess 186, along a mid-height of the piston 182 and circumferentially around the piston 182. The circumferential seal can encompass only the lower portion of the piston if desired. The seal 188 compresses into grooves which permit the pistons 182 to engage the continuous rod 30 in metal-to-metal contact. The seals 188 seal between the pistons 182, between the pistons 182 and the continuous rod 30 and between the pistons 182 and the bores in which the pistons 182 are installed.

Having reference to FIGS. 10A and 10B, gripping of the continuous rod 30 with less surface damage can be accomplished by several modifications, including minimizing a gap between the pistons 182 in the gripping position, making a gripping arc starting at an inward edge of the piston 182 at a radius of about 0.025 inches smaller than the largest continuous rod 30 to be gripped, making a straight gripping surface tangential to the gripping arc at about a 15 to 20 degree angle g and then forming another arc tangential to the straight gripping surface at a radius equal to the smallest continuous rod 30 to be gripped.

Claims

1. A method for installing and driving driven component of a rod-driven pump, the pump being fluidly connected at a bottom of a string of production tubing fluidly connected to a wellhead at surface, the method comprising:

providing a continuous rod;

coupling a downhole end of the continuous rod to an uphole end of the driven component;

running the continuous rod and driven component downhole through a bore of the production tubing;

ensuring the continuous rod is of sufficient length to be operatively connected to the pump in the wellbore and drivingly secured to a drive at surface; and

driveably securing the continuous rod to the drive at surface,

wherein the continuous rod is driven by the drive for pumping produced fluids to surface through the bore of the production tubing.

2. The method of claim 1 wherein the pump is a rotary pump having a rotor and a stator, the rotor being the driven component, and the drive is a drive head, the method comprising:

coupling the downhole end of the continuous rod to an uphole end of the rotor;

running the continuous rod and rotor downhole through a bore of the production tubing;

landing the rotor in the stator of the rotary pump for operatively engaging the rotor therein; and

once the rotor is engaged with the stator,

cutting the continuous rod above the drive head for driveably securing the continuous rod thereto,

wherein the continuous rod co-rotates with the drive shaft for rotation of the rotor in the stator in a first pumping direction for pumping produced fluids to surface through the bore of the production tubing.

3. The method of claim 2 further comprising coupling the downhole end of the continuous rod to the uphole end of the rotor using a threaded coupling.

4. The method of claim 3, when the continuous rod is to be disconnected from the rotor without removal of the rotor from the stator, the method further comprising;

rotating the continuous rod in a reverse direction for unthreading the downhole end of the continuous rod from the rotor.

5. The method of claim 2 further comprising driveably coupling the downhole end of the continuous rod to the rotor using a shear coupling.

6. The method of claim 5, when the rotor cannot be rotated in the stator in the first direction, the method further comprising:

rotating the continuous rod and the rotor in a reverse direction for pumping particulates downhole into the wellbore for freeing the rotor in the stator and thereafter

rotating the continuous rod and the rotor in the first pumping direction for pumping produced fluids to surface.

7. The method of claim 6 wherein, after rotating the rotor in the reverse direction, the rotor cannot be reverse-rotated in the stator, further comprising:

axially shearing the shear coupling for freeing the downhole end of the continuous rod from the rotor.

8. The method of claim 2 further comprising:

coupling the downhole end of the continuous rod to the rotor using a length of sucker rod, the sucker rod being welded, at an uphole end, to the downhole end of the continuous rod and having the threaded coupling at the downhole end for threaded connection to the rotor.

9. The method of claim 1 wherein the pump is a reciprocating pump, the driven component being a plunger, and the drive is a pumpjack, the method further comprising:

coupling the downhole end of the continuous rod to the uphole end of the plunger using a threaded coupling.

10. The method of claim 9, when the continuous rod is to be disconnected from the pump, the method further comprising;

rotating the continuous rod for unthreading the downhole end of the continuous rod from the plunger.

11. The method of claim 1 wherein the pump is a reciprocating pump, the driven component being a plunger, and the drive is a pumpjack, the method further comprising:

coupling the downhole end of the continuous rod to the plunger using a shear coupling.

12. The method of claim 11 wherein the continuous rod is to be disconnected from the pump, further comprising:

axially shearing the shear coupling for freeing the downhole end of the continuous rod from the plunger.

13. The method of claim 1, when particulates deposit in the pump, further comprising:

inserting a cleanout tubing string into the bore of the production tubing in a production annulus formed between the continuous rod and the production tubing;

passing the cleanout tubing string substantially unrestricted through the production annulus to the coupling of the continuous rod to the driven component of the pump; and

providing fluid through the cleanout tubing string for cleaning particulates from the pump.

14. A method for installing and driving a rotor in a stator of a rod-driven rotary pump, the pump being fluidly connected at a bottom of a string of production tubing fluidly connected to a wellhead at surface, the method comprising:

providing a continuous rod;

coupling a downhole end of the continuous rod to an uphole end of the rotor;

running the continuous rod and rotor through a bore of the production tubing;

landing the rotor in the stator of the rotary pump for operatively engaging the rotor therein; and

once the rotor is engaged with the stator, locking the continuous rod in the wellhead; cutting the continuous rod at a length calculated to extend above a drive head when installed on the wellhead; installing the drive head to the wellhead, the continuous rod passing through a hollow drive shaft in the drive head; and driveably securing the continuous rod thereto above the drive head,

wherein the continuous rod co-rotates with the drive shaft for rotation of the rotor in the stator in a first pumping direction for pumping produced fluids to surface through the bore of the production tubing.

15. The method of claim 14 further comprising coupling the downhole end of the continuous rod to the uphole end of the rotor using a threaded coupling.

16. The method of claim 15, when the continuous rod is to be disconnected from the rotor without removal of the rotor from the stator, the method further comprising;

rotating the continuous rod in a reverse direction for unthreading the downhole end of the continuous rod from the rotor.

17. The method of claim 14 further comprising coupling the downhole end of the continuous rod to the rotor using a shear coupling.

18. The method of claim 17, when the rotor cannot be rotated in the stator in the first direction, the method further comprising:

co-rotating the continuous rod and the rotor in a reverse direction for pumping particulates downhole into the well for freeing the rotor in the stator and thereafter

co-rotating the continuous rod and the rotor in the first pumping direction for pumping produced fluids to surface.

19. The method of claim 18 wherein after co-rotating the continuous rod and the rotor in the reverse direction, the rotor cannot thereafter be co-rotated in the stator in the first pumping direction, further comprising:

axially shearing the shear coupling for freeing the downhole end of the continuous rod from the rotor.

20. The method of claim 14 further comprising:

coupling the continuous rod to the rotor using a length of sucker rod welded, at an uphole end, to the downhole end of the continuous rod and having a threaded end at the downhole end for threaded connection to the rotor.

21. The method of claim 14, when particulates deposit in the stator inhibiting co-rotation of the rotor, further comprising:

inserting a cleanout tubing string into the bore of the production tubing in a production annulus formed between the continuous rod and the production tubing;

passing the cleanout tubing string substantially unrestricted through the production annulus to the coupling of the continuous rod to the rotor; and

providing fluid through the cleanout tubing string for cleaning particulates from the pump.

22. A method for servicing a rod-driven pump fluidly connected to a bore of a production tubing in a wellbore comprising:

driveably connecting an uphole end of a continuous rod to a drive at surface, the continuous rod extending through the bore of the production tubing from the drive to the pump;

providing a coupling for driveably connecting between a downhole end of the continuous rod and the pump;

inserting a cleanout tubing string into the bore of the production tubing in a production annulus formed between the continuous rod and the production tubing, the cleanout tubing string passing within the production annulus, substantially unrestricted by the continuous rod therein, to the coupling at the downhole end of the continuous rod; and

circulating cleanout fluids through the cleanout tubing string.

23. The method of claim 22 further comprising:

providing a threaded coupling for connecting between the downhole end of the continuous rod and the pump.

24. The method of claim 22 further comprising:

providing a shear coupling for connecting between the downhole end of the continuous rod and the pump.

25. A rod-driven pumping system comprising:

a drive positioned at surface;

a continuous rod driveably connected to the drive and extending downhole through a bore of a production tubing to a pump, forming a production annulus therebetween; and

a coupling connecting between the continuous rod and the pump, the production annulus having a maximized pass-by clearance along a length of the continuous rod from the wellhead to the coupling at the pump and being sufficient to permit a cleanout tubing to pass substantially unrestricted therethrough.

26. The rod-driven pumping system of claim 25 wherein the coupling is a threaded coupling.

27. The rod-driven pumping system of claim 25 wherein the coupling is a shear coupling.

28. The rod-driven pumping system of claim 25 wherein the system further comprises a length of sucker rod welded at an uphole end to a downhole end of the continuous rod and having threads at a downhole end for connection to the coupling.

29. The rod-driven pumping system of claim 25 wherein the pump is a rod-driven progressing cavity pump having a stator and a rotor operatively engaged within the stator for rotation therein and wherein,

the drive comprises a drive head having a hollow drive shaft supported on a wellhead at surface, the continuous rod being driveably connected through the hollow drive shaft of the drive head; and

the coupling connects between the continuous rod and the rotor.

30. A rod string for driving a pump in a wellbore, the rod string comprising:

a continuous rod having an uphole end for drivingly connecting to a drive at surface and a downhole end for connection to the pump; and

a coupling for connecting between the downhole end of the continuous rod and the pump.

31. The rod string of claim 30 further comprising

a length of sucker rod having an uphole end welded to the downhole end of the continuous rod and having a downhole end for connection to the coupling.

32. The rod string of claim 30 wherein the coupling is a threaded coupling.

33. The rod string of claim 31 wherein the coupling is a threaded coupling and wherein the downhole end of the length of sucker rod is threaded for connection to the coupling.

34. The rod string of claim 30 wherein the coupling is a shear coupling.