USRE43410E1 - Universal carrier for grippers in a coiled tubing injector - Google Patents

Abstract

The gripping element of a coiled tubing injector has a carrier and a removable gripping shoe mounted to the carrier. The removable shoe slides onto slots formed on the carrier and is floated on the carrier by inserting an elastomeric pad sandwiched between the carrier and shoe. A manually depressible spring along ones side of the carrier prevents the shoe from sliding out of the slots during operation of the injector.

Description

This application claims the benefit of U.S. provisional application no. 60/045,365, filed May 2, 1997, which application is incorporated herein by reference.

FIELD OF THE INVENTION

The invention relates generally to coiled tubing injectors for handling a continuous length of tubing or pipe for insertion into or removal from a well bore, and for drilling well bores. More particularly, it concerns gripping elements used by such injectors.

BACKGROUND OF THE INVENTION

Continuous, reeled pipe is generally known within the industry as coiled tubing and has been used for many years. It is much faster to run into and out of a well bore than conventional jointed, straight pipe.

Coiled tubing is run into and out of well bores using what are known in the industry as coiled tubing injectors. The name derives from the fact that, in preexisting well bores, the tubing must be literally forced or “injected” into the well through a sliding seal to overcome the well pressure until the weight of the tubing exceeds the force produced by the pressure acting against the cross-sectional area of the tubing. However, once the weight of the tubing overcomes the pressure, it must be supported by the injector. The process is reversed as the tubing is removed from the well.

The only method by which a continuous length of tubing can be either forced against pressure into the well, or supported while hanging in the well bore or being lowered or raised is by continuously gripping a length of the tubing just before it enters the well bore. This is achieved by arranging continuous chain loops on opposite sides of the tubing. The continuous chains carry a series of grippers which are pressed against opposite sides of the tubing and grip the tubing.

Coiled tubing has traditionally been used primarily for circulating fluids into the well and other work over operations, rather than drilling, because of its relatively small diameter and because it was not strong enough, especially for deep drilling. However, in recent years, coiled tubing has been increasingly used to drill well bores. For drilling, a turbine motor suspended at the end of the tubing and is driven by mud or drilling fluid pumped down the tubing. Coiled tubing has also been used as permanent tubing in production wells. These new uses of coiled tubing have been made possible by larger, stronger coiled tubing.

SUMMARY OF THE INVENTION

A coiled tubing injector according to the present invention includes a quick-release carrier for mounting gripping shoes to chains of the injector. The carrier enables removal and replacement of grippers in the field without tools, even when the injector is operating. An injector thus may be quickly adapted to run coiled tubing within a wide range of diameters, for purposes of a well work over to drilling. Furthermore, an injector having grippers according to the present invention may be used to run conventional jointed, straight pipe, or a tool string on the end of coiled tubing. The diameter of joints are larger than the diameter of the pipe. Tool strings have various diameters. The quick-release carrier enables gripping shoes to be easily removed to accommodate a joint or a tool as it passes through the injector during operations. Gripping shoes can be easily replaced with gripping shoes that have the appropriate size and shape for gripping the tool. All shoes are sized so that, when attached to the injector, they have same centerline or axis as the other shoes. Thus, gripping shoes of differing sizes can be used on the injector to grip a downhole tool or irregularly sized object in the pipe string as it is passing through the injector.

These and other aspects and advantages of the invention are discussed below in connection with a preferred embodiment illustrated by the appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of a coiled tubing injector intended to be representative of coiled tubing injectors generally, but with grippers according to the present invention.

FIG. 2 is a front elevational view of the coiled tubing injector shown inFIG. 1.

FIG. 3 is a left side elevational view of the coiled tubing injector shown inFIGS. 1 and 2.

FIG. 4 is an plan view of a drive chain of a coiled tubing injector having gripper carriers according to the present invention.

FIG. 5 is a side, elevational view, partially sectioned, of a gripper with a first shoe type mounted on one of the gripper carriers on the drive chain ofFIG. 4.

FIG. 6 is a side, elevational view, partially sectioned, of a gripper with a second shoe type mounted on one of the gripper carriers on the drive chain ofFIG. 4.

FIG. 7 is a side, elevational view, partially sectioned, of a gripper with a third shoe type mounted on one of the gripper carriers on the drive chain ofFIG. 4.

FIG. 8 is a perspective view of the gripper carrier and the gripper shoe ofFIG. 6 before as one is being mounted to the other.

FIG. 9 is a side, elevational view of the gripper shoe mounted on the gripper carrier ofFIG. 8.

FIG. 10 is a top, plan view of the gripper shoe ofFIG. 6.

FIG. 11 is a partially sectioned, end view of the gripper shoe ofFIG. 10.

FIG. 12 is a partially sectioned, side view of the gripper shoe ofFIG. 10.

FIG. 13 is a bottom, plan view of the gripper shoe ofFIG. 10.

FIG. 14, is a top, plan view of the gripper carrier shown inFIGS. 4-9.

FIG. 15 is a side view of the gripper carrier ofFIG. 14.

FIG. 16 is a cross-section of the gripper carrier taken along section line16-16 inFIG. 15.

FIG. 17 illustrates flexing of a leaf spring of the gripper carrier.

DESCRIPTION

In the following description, like numbers refer to like elements.

FIGS. 1,2 and3 illustrate an example of a coiledtubing injector101. It is intended to be representative of coiled tubing injectors generally for purposes of describing the invention, even though it may differ from other prior art coiled tubing injectors in several important aspects.

Referring first toFIG. 1, coiled tubing is transported into the top of coiledtubing injector101 from a reel (not shown) on a “goose-neck”support103. The goose-neck support includes aframe105 supporting a plurality ofrollers107.Bracing108 extending fromcage109 positions the goose-neck support103 in proper relation to theinjector101. The cage also supports theinjector101 for transportation. Legs (not shown) may also be attached to the corners of the bottom of thecage101 to stand the injector above a well head (not shown).

Referring now toFIGS. 1,2 and3 together,injector101 includes two, continuous loop drive chains generally designated byreference numbers111 and113. The drive chains revolve generally within a common plane defined byaxes114 and116, which plane is normal toaxis118. Connected to each drive chain is a plurality ofgrippers115. Thedrive chains111 and113 are arranged in a conventional, opposing relationship. Eachdrive chain111 and113 is mounted on an upper drive sprocket (not shown) and alower drive sprocket119 and121, respectively. The upper drive sprockets are mounted withindrive housing117 and are not visible in these views. One set of bearings for the shafts of upper drive sprockets are mounted within bearinghousings118 and120, respectively. The other set of bearings on which the shafts of upper drive sprockets are journalled are mounted to the opposite side of thedrive housing117.

A box-shaped frame is formed from two, parallelfront plates123 and125, separated by side plate127 and a second side plate parallel to side plate127 but not visible in these views. This frame supports thedrive housing117 andtransmission gear box131 at its upper end, and the lower drive sprockets at its lower end.

Thelower drive sprockets119 and121 are connected toshafts133 and135, respectively. The ends of each shaft is journalled on opposite sides of the injector frame within amovable carrier137. Each carrier is mounted so that it may slide vertically within anelongated slot139 defined in either thefront plate123 orrear plate125. Ahydraulic cylinder141 is inserted between the top of eachcarrier137 and ablock143 connected to the frame at the top of eachelongated slot139. Eachcylinder141 applies a spreading force between the stationary block and the movingcarrier137 to push down on thelower drive sprockets119 and121 and thus tension the drive chains.

Although not visible,coiled tubing injector101 includes two skates, one for each drive chain, for forcing thegrippers115 toward each other as they enter the area between the two drive chains through which the coiled tubing passes. Examples of such skates are shown in U.S. Pat. No. 5,309,990 and are well known in the art. A plurality ofhydraulic cylinders145 are used to pull together the skates and maintain uniform gripping pressure against coiled tubing (not shown) along the length of the skates. Eachcylinder145 is connected at each end through a clevis and pin to aneyelet147 of a bar extending behind one of the skate and terminating in another eyelet connected to another piston on the opposite side of the injector.

At the bottom of the injector, astripper149 carried by astripper adapter151, connects the injector to a well head. Power for driving the injector is provided by a high speed, low torquehydraulic motor153 coupled with thetransmission gear box131 through brake155. The hydraulic motor is supplied with a pressurized hydraulic fluid in a conventional manner.

Referring now toFIGS. 4-7,drive chain111 includes a roller chain having two strands,157 and159, on either side of the row ofgrippers115. (Note that inFIG. 4, the grippers have their shoes removed, revealinggripper carriers161.) The roller chain is of well-known construction.Rollers163 are mounted onpins165 which extend from an exterior side ofstrand157, throughgripper carrier161, to the exterior side of strand159. Roller links167 are disposed on opposite sides of each pair ofrollers163.Pin link plates169 are outboard of each roller plate and connect pairs of pins.

Mounted to an underside ofgripper carriers161 are a pair ofroller bearings171 and173 which ride upon the skates of the injector. The roller bearings are rotatably mounted onpin175.

As illustrated byFIGS. 5,6 and7, a plurality of different shoes may be attached to thesame gripper carrier161. For example, inFIG. 5, “V”-shapedgripper shoe179 can support large diameter tubing or pipe, the outer diameter of which is indicated in phantom by dashedcircle181. InFIG. 6, it is round-shapedgripper shoe adaptor183 which may hold various sizes of rounded gripper shoes disposed therein (not shown) for gripping smaller diameter pipes and tubing. InFIG. 7, a comparativelysmall gripper shoe185 is shown mounted togripper carrier161. When installed in an injector, the position of the center line of the pipe to be gripped bygripper shoe185 will be the same as the center line of the larger diameter pipe to be gripped bygripper shoe179. This allows different shoes to be installed on the same injector in order to accommodate gripping of irregularly shaped tools or joints being passed through the injector without changing the relative position of the skates on which the gripper carriers roll.

Each of the gripper shoes may be quickly inserted and removed from thegripper carrier161 without the use of tools. This is especially useful when running conventional, jointed pipe rather than coiled tubing, or when running a tool string corrected to one end of the coiled tubing. One or more gripper shoes are removed from each drive chain to pass the pipe joint or tool. InFIG. 5, for example, the diameter of a joint is illustrated by dashedcircle187 and the outer diameter of the pipe by dashedcircle181.

Referring now toFIGS. 8-17, to mount a gripper shoe to thecarrier161, auniversal base189 is integrally formed on the bottom of the gripper shoe. The base mounts to the gripper shoe carrier using a tongue and groove type of mounting that allows the gripper shoe to be slid onto and out of the mounting in directions that, when the injector is in an operational position, are generally parallel to the ground, which directions are generally oriented alongaxis118, and perpendicular to the directions in which the chain moves, which directions are generally oriented alongaxis114. Thus, forces exerted by the pipe string on the gripping elements, which forces are primarily alongaxis114, tend to act in a direction alongaxis114. along which the grippers shoe is slid into and out of the gripper shoe carriers. For purposes of explanation only, thegripper shoe adaptor183 is chosen to illustrate this base. The same base is found on each of the gripper shoes179 and185. Theuniversal base189 includes four mounting lugs,191a,191b,191c and191d which function as tongues that slide into grooves in the form of slots defined by ledges195 and rails197 around the periphery of the carrier. When the gripper shoe is lowered toward the carrier, lug191a fits intoslot193a defined betweenledges195a and195c extending fromleft side rail197a.Lug191b fits inslot193b defined betweenledges195b and195c extending fromright side rail197b.Lugs191c and191d fit over the end of the side rails197a and197b, respectively. The base of the gripper shoe presses against a flat,metal leaf spring199, forcing it down to allow thegripper shoe base189 to be slid into the base, towardend rail201. When base is pushed back to the end rail, thelugs191a-191d pass underledges195a-195d, respectively and cooperate with the ledges to retain the gripper shoe on the carrier.Leaf spring199 then pops up, as best shown inFIG. 9, and retain the gripper show on the carrier. During normal operation of the injector, lateral forces which would push the gripping shoe against the leaf spring are not substantial. Nevertheless, the leaf spring does possess substantial lateral strength. To reduce the effect of forces acting as the gripper shoes in lateral direction, the orientation of the carriers may be alternated on the chain, thus preventing the springs from carrying the lateral load.

The flat,metal leaf spring199 is formed of anarched body section199a andfeet199b and199c. The feet of the spring are trapped within open-endedslots203a and203b formed in thecarrier161. Depressing the leaf spring flattens it and causes the feet to slide outward, as illustrated in phantom byFIG. 17. When the feet slide outward, any dirt or other debris which may have accumulated in theslots203a and203b is pushed out through their open ends. The spring force of the spring is such that it may easily be manually depressed to release the gripper shoe, or pulled to remove the spring to clean a shallow channel205 formed in the carrier between theopen slots203a and203b for accommodating the body of the leaf when it is depressed.

Sandwiched between thegripper shoe base189 and thecarrier161 is anelastomeric pad206 of high spring rate which allows the gripper shoe to float on thecarrier161. Slightly floating the gripper shoe allows the gripper shoe to automatically make small adjustments in its alignment with the coil tubing or pipe as it engages the tubing or pipe, thus providing a more even distribution of gripping forces across the shoe. The elastomeric pad also accommodates manufacturing tolerances that result in slight variations in the distances between the skate on which the roller bearings of the gripper carriers ride and the centerline of the pipe or other object being gripped. Thus, more of the gripping shoes will make good gripping contact with the pipe, improving overall grip. Preferably, only gripping shoes are used that have fixed shapes conforming to the normal shape of the pipe, and that surround substantially half of the circumference of the pipe. The fixed shape shoes cause the pipe to maintain its normal shape as strong forces are applied to the pipe, thus preventing deformation. By forcing the pipe to retain its normal shape and floating the gripper shoe for better alignment of the shoe with the pipe, contact area between the gripping shoe and pipe is increased. Furthermore, greater force may be applied to the pipe without concern of deformation. Thus, with greater contact area and force, gripping is improved.

Eachshoe carrier161 is mounted to one of the two drive chains by inserting one of the chain pins165 (FIG. 5) through each of thebores207a and207b.Rollers171 and173 (FIGS. 5-7) are mounted betweenflanges209a,209b and209c.Roller175 extends thoughopenings211a and211b inflanges209a and209b, and in a similar opening inflange209c which is not visible in these views.

Gripping shoe adaptor183 includesrims213a and213b located at opposite ends for retaining removable gripping elements (not shown). Gripping elements may thus be replaced when worn or changed in size or shape, or to accommodate passing of downhole tools or other downhole assemblies having different diameters than the pipe.

The forgoing embodiments are but examples of the invention. Modifications, omissions, substitutions and rearrangements may be made to the forgoing embodiments without departing from the invention as set forth in the appended claims.

Claims (24)

What is claimed is:

1. A tube conveying apparatus comprising:

a frame;

a pair of continuous drive chains supported on the frame and revolving in a commom common plane, the pair of drive chains having opposed, elongated parallel runs spaced apart to form a path for engaging tubing passing therebetween; and

a plurality of grippers carried on each of the pair of drive chains;

wherein, each gripper includes a carrier mounted to the chain and a pipe gripping shoe mounted to the carrier, the shoe including a plurality of tongues for sliding, in directions generally perpendicular to the common plane, in corresponding grooves formed by the carrier for retaining the shoe on the carrier, the tongues and grooves being arranged for enabling dismounting the shoe in a sliding motion in a direction generally perpendicular to the common plane.

2. The apparatus ofclaim 1 wherein the carrier includes a releasable retaining member for preventing the shoe from sliding out of the carrier along one of the directions perpendicular to the common plane.

3. The apparatus ofclaim 1 further including a depressible spring extending from the carrier in a direction parallel with the common plane for blocking sliding of the shoe out of the carrier along one of the directions perpendicular to the common plane, wherein depressing the spring allows sufficient clearance between the spring and the shoe to allow the shoe to slide out of carrier.

4. The apparatus ofclaim 1 further wherein, in each gripper, the carrier includes a leaf spring having an arched portion between two end portions, each end portion extending into one of two slots formed in the carrier, the arched portion extending in a direction parallel with the common plane for blocking sliding of the shoe out of the carrier along one of the directions perpendicular to the common plane; whereby manually depressing the arched portion toward the carrier causes each of the two end portions of the spring to slide further into the slots and flattens the arched portion of the spring, resulting in sufficient clearance between the arched portion of the leaf spring and the shoe to allow the shoe to slide out of the carrier.

5. The apparatus ofclaim 4 wherein each of the slots have an opening opposite where the end of the leaf springs enter, whereby debris which may accumulate in each of the slots is forced out of the slots by depressing the leaf spring.

6. The apparatus ofclaim 4 wherein, in each gripper,

the carrier has an outer periphery, and the grooves are formed by ledges extending along opposites sides of the outer periphery of the carrier; and

the leaf spring is disposed along the periphery of the carrier, between the ledges.

7. The apparatus ofclaim 6 wherein, in each gripper,

the tongues on each shoe include four lugs; and

the ledges extending along opposite sides of the outer periphery of the carrier have openings through which an opposing pair of lugs may pass as the shoe is lowered toward the carrier during mounting, while the other lugs pass by to the side the ledges.

8. The apparatus ofclaim 1 wherein the carrier further includes a fixed rail for retaining sliding movement of a shoe in one of the directions perpendicular to the common plane, and a releasable retaining member for preventing the shoe from sliding out of the carrier along the other of the directions perpendicular to the common plane.

9. The apparatus ofclaim 1 further including an elastomeric pad positioned between the shoe and the carrier.

10. A tubing gripper comprising:

a carrier having front and back sides, means for mounting the back side of the carrier to a chain, two opposing slots formed on the front side of the carrier, each of the slots having an open end and closed end; and

a pipe gripping shoe removably mounted to the carrier, the shoe including a base portion having lugs for sliding along a first axis into the open ends of the slots, the slots and lugs thereby cooperating to retain the shoe on the carrier in all directions except along the first axis.

11. The gripper ofclaim 10 further comprising manually-depressible means for blocking, in an extended position, movement of the lugs out of the open ends of the slots, and for allowing movement, when in a depressed position, of the lugs out of the open ends of the slots of the carrier.

12. The gripper ofclaim 11 wherein the means for blocking movement includes a spring.

13. The gripper ofclaim 12 wherein the spring is a leaf spring having an arched portion between two ends inserted into slits in the carrier, the arched portion extending in a plane generally perpendicular to the axis for blocking sliding of the shoe out of the carrier along one of the directions parallel to the axis; whereby, manually depressing the arched portion toward the carrier causes each of the two ends of the spring to slide further into the slits and flattens the arched portion of the spring, resulting in sufficient clearance between the arched portion of the leaf spring and the shoe to allow the shoe to slide out of the carrier.

14. The gripper ofclaim 11 wherein the means for blocking movement incudes includes a leaf spring having an arched portion between two ends inserted into slits formed in the carrier, the arched portion extending in a plane generally perpendicular to the pivot axis of the carrier for blocking sliding of the shoe out of the carrier along one of the directions parallel to the axis; whereby manually depressing the arched portion toward the carrier causes each of the two ends of the spring to slide further into the slits and flattens the arched portion of the spring, resulting in sufficient clearance between the arched portion of the leaf spring and the shoe to allow the shoe to slide out of the carrier.

15. The gripper ofclaim 10 wherein the carrier has an outer periphery, and wherein the slots are defined by ledges located along opposites sides of the side edges.

16. The gripper ofclaim 10 further comprising an elastomeric pad positioned between the shoe and the carrier.

17. The gripper ofclaim 10 further comprising a releasable retaining member for blocking movement of the lugs out of the open ends of the slots.

18. A tube conveying apparatus comprising:

a frame;

a pair of continuous drive chains supported on the frame and revolving in a common plane, the pair of drive chains having opposed, elongated parallel runs spaced apart to form a path for engaging tubing passing therebetween; and

a plurality of grippers carried on each of the first and second pair of continuous drive chains;

wherein, each gripper includes,

a carrier mounted to the chain,

a pipe gripping shoe retained on the carrier, the pipe gripping shoe having a gripping portion having a rigid shape that fits around substantially one-half of an outer circumference of tubing to be injected, and

an elastomeric pad positioned between the carrier and shoe for floating the shoe on the carrier;

wherein,

the carrier has two opposing slots, each of the slots having an open end and closed end; and

the pipe gripping shoe has lugs for sliding into the open ends of the slots, the slots and lugs thereby cooperating to retain the shoe on the carrier.

19. A tube conveying apparatus comprising:

a frame;

a pair of continuous drive chains supported on the frame and revolving in a common plane, the pair of drive chains having opposed, elongated parallel runs spaced apart to form a path for engaging tubing passing therebetween; and

a plurality of grippers carried on each of the pair of drive chains;

wherein, each gripper includes a carrier mounted to the chain and a gripping shoe connected to the carrier by means of tongues that slide into corresponding grooves in directions generally perpendicular to the common plane for retaining the shoe on the carrier, the tongues and grooves being arranged to retain the gripping shoe on the carrier in all directions but the directions generally perpendicular to the common plane.

20. The apparatus ofclaim 19 wherein the carrier includes a retaining member for preventing the shoe from sliding out of the carrier alone one of the directions perpendicular to the common plane.

21. The apparatus ofclaim 19 further including a depressible spring extending from the carrier in a direction parallel with the common plane for blocking sliding of the shoe out of the carrier along one of the directions perpendicular to the common plane, wherein depressing the spring allows sufficient clearance between the spring and the shoe to allow the shoe to slide out of carrier.

22. The apparatus ofclaim 19 further wherein each gripper includes a leaf spring having an arched portion between two end portions, each end portion extending into one of two slots formed in the carrier, the arched portion extending in a direction parallel with the common plane for blocking sliding of the shoe out of the carrier along one of the directions perpendicular to the common plane; whereby manually depressing the arched portion toward the carrier causes each of the two ends of the spring to slide further into the slots and flattens the arched portion of the spring, resulting in sufficient clearance between the arched portion of the leaf spring and the shoe to allow the shoe to slide out of the carrier.

23. The apparatus ofclaim 22 wherein each of the slots have an opening opposite where the end Of the leaf springs enter, whereby debris which may accumulate in each of the slots is forced out of the slots by depressing the leaf spring.

24. The apparatus ofclaim 19 further including an elastomeric pad positioned between the shoe and the carrier.

Images