This application claims the benefit of U.S. Provisional Application No. 61/583,230 filed January 5, 2012, which is incorporated in its entirety, for all purposes, by reference.

TECHNICAL FIELD OF THE INVENTION

The invention pertains generally to oilfield operations involving use of coiled tubing. BACKGROUND

Coiled tubing is commonly used in a wide range of oilfield services and operations. It can be run into and out of a well bore at a high rate, relative to straight, jointed pipe, and, unlike wire line, it can be pushed into the well bore. Coiled tubing refers to a continuously string of steel pipe that is continuously milled and coiled onto a large take-up reel for transportation and handling. With diameters from 0.75 inches to more than 4 inches, coiled tubing can possess a yield and tensile strengths from 50,000 pounds-force per square inch (PSI) to more than 120,000 PSI, and has been manufactured in lengths greater than 30,000 feet. It can be used, for example, for drilling, but it is more often used after the well is drilled for logging, cleanouts, fracturing, cementing, fishing, completion and production related operations.

Coiled tubing is run in and out of well bores using machines called coiled tubing injectors. The name "coiled tubing injector" derives from the fact that, in preexisting well bores, the tubing may need to be forced or "injected" into the well through a sliding seal to overcome the pressure of fluid within the well, until the weight of the tubing in the well exceeds the force produced by the pressure acting against the cross-sectional area of the pipe. However, once the weight of the tubing overcomes the pressure, it must be held by the injector.

There are a number of different types and configurations of coiled tubing injectors capable of handling coiled tubing used in oilfield operations. Most coiled tubing injectors have a head comprised of two continuous chains, each mounted on sets of spaced-apart sprockets, so that there is an extended length of chain between the sprockets. At least one of the chains is driven by a motor— typically hydraulic, though other types of motors can be used— connected to one or more of the sprockets. The chains are arranged so that the coiled tubing entering the injector is held between the chains by grippers mounted to each of the chains. The grippers are pressed against the outer diameter of the tubing thereby generating a frictional force parallel to the axis of the tubing. The frictional force is directly related to the normal force applied by the grippers.

FIGURES 1 and 2 illustrate examples of equipment typically used when conducting operations on a previously drilled well after a drilling rig has been removed. A reel 10 of coiled tubing is mounted on a trailer 11 for transport to the site. A coiled tubing injector, control cabin and other equipment for operating the injector is sometimes referred to as a "coiled tubing unit," and is generally designated in the figures by the reference number 12. As coiled tubing 14 is unspooled from the reel, or is spooled back onto the reel, it is guided into alignment with the chains of the coiled tubing injector by a tubing support guide 16. Because such guides are typically arched, they are sometimes referred to as "gooseneck" supports. When the coiled tubing injector is deployed, the guide is connected to the frame of the coiled tubing injector so that it has a fixed relationship with the coiled tubing injector while the injector is being operated. Generally, the guidance arch is positioned or oriented so that the coiled tubing is thread into the top of the head of the injector, between its rotating chains or, optionally, into a straightener mounted to the frame, on top of the injector head, for removing the bend in the tubing before it enters the injector head. (As used in this description, "coiled tubing injector" refers to the injector head with or without the straightener, unless the context indicates otherwise.) The reel must maintain tension on the coiled tubing in order to wind the tubing coiled on the reel and to keep it wound on the reel, as it is being unspooled or spooled. The guidance arch prevents the coiled tubing from kinking or otherwise being damaged by the tension the reel is applying to the tubing. However, a guidance arch is typically attached to the frame of the coiled tubing injector in a manner that allows it to be attached or connected in different positions or orientations. For example, the best positioning or orientation may depend on the diameter of tubing being used and whether the tubing is being lowered or pushed into the well bore or pulled out of the well bore. When the pipe is coming off a reel, it has relatively more curve than when it is pulled from the well, which may affect how the guidance arch is fixed to the injector. Thus, "fixed relationship" does not imply one that cannot allow for adjustment.

When being used, the coiled tubing injector is positioned over the well head, high enough to accommodate one or more blow out preventers 20, a riser 22, and other equipment that might be connected to the wellhead through which the coiled tubing must pass before entering the well bore. The riser is made up from one or more sections of straight pipe that extends from the blow out preventers attached to the wellhead. The riser is used to accommodate elongated, rigid tools that are attached to the end of the coiled tubing prior to being lowered into the well bore. The coiled tubing injector is connected to the riser with a stripper, through which the coiled tubing is pushed or pulled. Because there is no derrick or platform, a temporary structure erected above the wellhead, or a mobile crane driven to the site, is used to position and hold the injector in place.

FIGURE 1 illustrates an example of the use of a portable structure 24, which is temporarily erected from one or more stackable sections transported to the site, for holding the coiled tubing injector in place above the wellhead. FIGURE 2 illustrates the use of a high capacity, self-propelled crane 26 to lift and hold the coiled tubing injector 18 and guidance arch in the proper position during the well servicing job. The crane is generally placed opposite the wellhead of the coiled tubing reel 10 or, if necessary, to one side. Some or all of the weight of the injector and the tubing is transferred to the boom of the crane. However, the tension on the section 14 of coiled tubing between coiled tubing injector 18 and the reel 10 also applies a lateral force on the guidance arch 16, which is transferred to the coiled tubing injector 18, inducing a bending moment on the wellhead. Taller wellheads, which are increasingly used to accommodate long downhole tools and larger diameter coiled, tubing, mean greater bending moments. The structure 24 can be designed to handle the load expected from the bending moment. However, in the case of the crane, the crane operator has to operate the crane in a manner that places an opposing force on the coiled tubing injector 18. This opposing force is usually applied by pulling back and away from the reel 10 in an attempt to reduce the tension loads that produce the bending moment on the wellhead. Knowing how hard to pull back on the tubing injector usually involves guesswork and, in some situations, the tension in the tubing can exceed the capacity of the crane to hold a lateral force. There have, therefore, been a number of instances in which wellheads have been pulled over and cranes toppled. SUMMARY

As the diameter, wall thickness and yield strength of coiled tubing used in well operations increases, more tension on the coiled tubing will be required to wind it around a storage reel. Reels will need to impose higher tensions on the segment of coiled tubing extending between the reel and the coiled tubing injector. Furthermore, larger tubing also requires taller wellheads. More tension and taller wellheads result in much higher bending moments applied on the wellheads.

In one example of a method and apparatus for conducting well servicing operations using coiled tubing, a coiled tubing guide for supporting coiled tubing as it turns into the top of a coiled tubing injector is affixed to a support structure, above a coiled tubing injector, without it being affixed to the coiled tubing injector. The load induced by tension on the coiled tubing is transferred through the coiled tubing guide to the support structure rather than to the coiled tubing injector. The tension from the reel thus no longer induces a bending moment in the wellhead. Greater tension can be applied to the coiled tubing by the reel without increasing bending moment on the wellhead.

In another example, a boom of a crane holding a coiled tubing injector above a wellhead is fitted with a tubing guide for supporting coiled tubing as it transitions from the reel into the coiled tubing injector. Alternately, a crane or extendable mast positions the coiled tubing guide above the coiled tubing injector, while the coiled tubing injector is held by a separate crane.

In yet another example, the reel is positioned with respect to an elongated support structure such as a crane boom or telescoping mast, so that the majority of the load induced by the tension on the coiled tubing is borne primarily as an axial, compressive load by the elongated support. Although a bending load is also placed on the elongated support structure, to the extent that it is upward, it counters the downward bending load on the mast caused by the coiled tubing injector if it is being supported by the elongated support structure, and the weight of the elongated support structure. By more closely aligning the induced load with the axis of the elongated support structure, the guesswork involved with operating that structure, in particular a crane, to counteract the load is lessened.

In yet another example, the coiled tubing guide is attached to the crane boom or telescoping mast using a coupling for allowing it to tilt and/or to swivel side-to-side. This adjustability allows the angle between the coiled tubing and the elongated member carrying the coiled tubing support boom angle to vary, thereby allowing more flexibility in positioning the elongated support structure and the reel.

In an alternate embodiment of a method and apparatus for conducting well servicing operations using coiled tubing, an injector with coiled tubing guide is suspended from a crane boom, telescoping mast or other elongated support structure and coupled with an end of the elongated support structure through a coupling that resists bending while permitting, at least during movement of the coiled tubing injector above the well head, relative rotation of the coiled tubing injector with respect to the crane. The coiled tubing guide is not mounted to the end of the crane. The coupling prevents a bending moment from being applied to the wellhead as a result of the tension of the coiled tubing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGURE 1 is a perspective view of a prior art arrangement of equipment used for running coiled tubing in a bore of an oil or gas well.

FIGURE 2 is a perspective view of a prior art arrangement of equipment used for running coiled tubing in a bore of an oil or gas well.

FIGURE 3 is a perspective view of an example of a support for guiding coiled tubing mounted to a boom of a crane holding a coiled tubing injector.

FIGURES 4A and 4B are side views of a coupling for connecting a coiled tubing support guide to mast or boom of a crane in two different positions.

FIGURES 4C and 4D are bottom views of the coupling of FIGURE 4A in two different positions or orientations.

FIGURES 5A and 5B are side views of an alternate coupling for connecting coiled tubing support guide to a mast or boom.

FIGURES 6A and 6B are side and front views of another arrangement of a coiled tubing support guide connected to a boom of a crane.

FIGURE 7 is a side view of an alternative coiled tubing support guide connected to a boom of a crane.

FIGURES 8A and 8B are front and side views of yet another arrangement of a coiled tubing support guide connected with a boom of a crane. FIGURE 9 is a side view of a telescoping mast, to which a coiled tubing support guide is attached, holding a coiled tubing injector above well head, and a coiled tubing unit positioned in line with the mast and the well head, but behind the vehicle carrying the mast.

FIGURE 10 is another alternate embodiment with a coiled tubing support guide attached to a mast working in conjunction with a crane that supports a coiled tubing injector.

FIGURE 11 is a side view of an alternative embodiment, to the example of FIGURE 9, with a mobile, self-propelled crane in place of telescoping mast.

FIGURE 12 is a side view of the components of FIGURE 11, with the coiled tubing unit placed beside the crane rather than in line with the crane and wellhead.

FIGURE 13 is a side view of another alternative example of an arrangement of a coiled tubing support guide on a crane, from which a coiled tubing injector is suspended, with a coiled tubing unit positioned between a wellhead and the crane.

FIGURE 14 is a side view of an alternative example of an arrangement of a coiled tubing support guide on a crane, from which a coiled tubing injector is suspended, with a coiled tubing unit positioned opposite a wellhead from the crane.

FIGURE 15A is a side view in representative environment of a first example a bending- resistant coupling formed between the end of crane boom and a coiled tubing injector unit.

FIGURE 15B is a perspective view of just the coupling of FIGURE 15B.

FIGURE 15C is a perspective view of the coupling of FIGURES 15A and 15B, without being attached to a crane.

FIGURE 16A is a side view in representative environment of a second example a bending-resistant coupling formed between the end of crane boom and a coiled tubing injector unit.

FIGURE 16B is a perspective view of just the coupling of FIGURE 16B.

FIGURE 16C is a perspective view of a detail of FIGURE 16B, showing two rings of the coupling in an engaged and a disengaged position.

FIGURE 17 is a perspective side view in a representative environment of an alternate method and apparatus for countering a side force on a coiled tubing unit by a crane that uses extension arm for enabling rigging of a line to counteract a side force on the coiled tubing injector.

FIGURE 18 is a top or plan view showing placement of a crane with respect to a coiled tubing unit and wellhead for hoisting and positioning the a coiled injector over the well head.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

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

In each of the examples of FIGURES 3-17, a coiled tubing injector 18 for injecting coiled tubing 34 into a well bore is positioned above the wellhead by an elongated support structure. An example of such an elongated support structure include crane 26 with a telescoping boom 38. Another example of such an elongated support structure is a telescoping mast 60, as shown in FIGURES 9-10.

A coiled tubing unit typically comprises a frame 18a to which is mounted a coiled tubing injector head 18b. However, in other embodiments, a coiled tubing injector can include more components, including for example a straightener. In other embodiments, the unit might omit an external frame, like frame 18a. The coiled tubing enters, in the examples of FIGURES 3-14 and 16-17, a straightener 19 that is mounted on top of a frame 18a of the coiled tubing injector 18. No straightener is shown in example embodiments of FIGURES 15A-15C, however such embodiments could be adapted to accommodate one. The tubing exits the straightener and enters the top of the coiled tubing injector head. The coiled tubing injector head 18b is, in this example, comprised of a pair of opposed endless chains with grippers (not visible) for conveying the tubing in and out of the wellhead. Coiled tubing 34 is fed from reel 10 into riser 22 when being lowered into the well. The elongated support structure (e.g. boom 38 of the crane or extendable mast 60) is used to position the coiled tubing injector 18 above the wellhead. The coiled tubing injector hangs from a main hook 42 that is connected by a main host line 44 to the head 40 of the elongated support structure. Upward and downward movement of the main hook 42 is directed by the main hoist line 44. The head 40 of the elongated support structure typically includes at least one sheave 45 or other type of wheel or pulley, ratably mounted on a load shaft 47, around which the hoist line is run.

The coiled tubing 34 is spooled at one end to a storage reel (not visible), such as reel 10 of FIGURES 1 and 2. The other end is routed from the storage reel upward to a coiled tubing guide, which, in this example, is comprised of an arched support guide 36, which is sometimes referred to as a gooseneck. The radius of the arched support guide 36 supports the coiled tubing 34 as it turns into the top of the coiled tubing injector, allowing the change of direction of the coiled tubing 34, from the upward direction from the storage reel to the downward direction to be received in the top of the coiled tubing injector 18. The radius or curvature of the arch allows the change in direction without kinking or otherwise excessively damaging the coiled tubing, which is under tension by the reel. (Note that coiled tubing is designed to be plastically deformed when it is wound and unwound from the reel, or otherwise gently bent, through a number of cycles.)

According to certain embodiments, the arched support guide 36 may further comprise a series of rollers to reduce the friction with the coiled tubing as it moves along the arched support guide 36. In the embodiment shown in FIGURE 3, the arched support guide 36 is disposed generally above and in-line with the boom 38. Alignment with the boom axis of the boom permits the line of force caused by the tension of the coiled tubing to be generally aligned with the axis to the boom of the crane, resulting in a majority of the load to be carried by the boom as an axial load with any remaining load causing a bending moment. The coiled tubing support guide is, in the embodiment illustrated in several of the figures, including FIGURE 3, attached to the boom of the crane by adjustable coupling 46. Alternately, the coiled tubing support guide is attached to the boom in a manner that does not allow the position or orientation of the tubing support guide to be adjusted, so that it has a fixed relationship to the central axis of the boom when attached. For example, the plane of the tubing support guide is aligned with the central axis of the boom or at a fixed angle to the central axis of the boom. The coiled tubing support guide is, in certain embodiments, such as the one shown in FIGURE 3, detachable or removable from the boom of the crane or other elongated support structure to allow for easier transportation.

An adjustable coupling, such as coupling 46, allows the position of the arched support guide, or any other type of coiled tubing support guide, to be adjusted along multiple axes. For example, an adjustable coupling may permit the arched support guide 36 to be adjusted by tilting it forward and backward. This allows better control over the routing of the coiled tubing and provides adjustability of the angle of the boom 38 with respect to the coiled tubing. In another embodiment, the adjustable coupling may permit the coiled tubing support guide to be moved or swung from one side of the boom to the other side and/or rotated so that the plane of the coiled tubing support guide is at an angle to the axis of the boom. This capability allows the position of the crane 26 with respect to the coiled tubing unit 12 to be varied. For example, if the tubing guide is rotated approximately 30 degrees, the crane 26 may be positioned generally along side of the coiled tubing unit 12. Allowing multiple positions of the ground equipment (coiled tubing unit and crane and/or telescoping mast) may be advantageous, especially at sites where there is a reduced clearance radius around the wellhead or there are other limitations on positioning of the equipment.

FIGURES 4A, 4B, 4C, and 4D illustrate a representative example of the basic components of coupling 46. Although shown and described in reference to an arched support mounted to one end of a boom, mast or other elongated support structure, it can be adapted for other types of coiled tubing support structures, such as those shown or described in connection with other figures. In this example, the coupling permits to rotate up and down, to pivot or swing to either side of the boom, and to swivel so that the plane in which the coiled tubing support guide lines can be adjusted and placed at an angle to the axis of the boom. In this example, the coupling includes three joints, 47, 49 and 51 , which are represented by pins, and parallel offset links 53, that allows the tubing support guide to pivot up and down about a generally horizontal axis (a first axis), to swivel or rotate about a second axis that, generally speaking, is oriented vertically (depending on the position first joint 47) and to swing from side to side about a third axis that is generally parallel to the second axis.

FIGURES 5A and 5B illustrate another representative example coupling 55 that is similar to coupling 46, but that does not swing from side to side. It omits joint 51 and offset links 53, with the arched support guide being connected to joint 49. The coupling is therefore adjustable in only two degrees of freedom: it moves up and down about the pin forming joint 47, and swivels or pivots about the pin forming joint 49. Although omitted for clarity, couplings such as couplings 46 and 55 would have additional elements for enabling the joints to be, in effect, locked in position or blocked from turning while tubing is being run. Furthermore, the positions of the joints could be controlled remotely using hydraulic cylinders or other types of positioning devices.

Although not illustrated, other examples of a coupling allows the tubing support guide only to be adjusted in one degree of freedom, or in more than three degrees of freedom

Coupling a coiled tubing support guide, in the manner shown in FIGS 4A-D or 5A-B, to an elongated support structure such as boom 38 allows the reel of coiled tubing to be placed on either side, behind or in front of a crane, telescoping mast, or other type of elongated support structure. When the coiled tubing 34 is tensioned, the tensile load is transferred to the boom 38 of the crane 26 and is not imparted on the coiled tubing injector 18, which is suspended over the well bore. Thus, the tension load can be accommodated independently of the coiled tubing injector 18. Moreover, with the coiled tubing guide support, in this example arched support guide 36, generally aligned with the boom 38 of the crane, the forces imparted on the crane as a result of tensioning the coiled tubing are primarily axial forces to the boom 38. Thus, the crane 26 is more easily controlled without requiring the crane operator to adjust or move the boom to counteract the load. If the arched support guide 36 is positioned so that the loading force induced by the tension in the coiled tubing is not aligned with the axis of the crane boom 38 or other elongated support structure, the elongated support structure may be subjected to bending moments, both upward and sideways. However, most cranes and other elongated support structures can handle some side loads. Alternatively, the crane or other elongated support structure can be positioned anywhere around the wellhead, provided that the crane is capable of handling the lateral or side loads induced by the tension in the coiled tubing.

FIGURES 6A and 6B are front and side views of an alternate embodiment of an arrangement of equipment for running coiled tubing in a well bore. This embodiment shows an arched support guide 36 guide similar to that shown in FIGURE 3. However, in this embodiment, the arched support guide 36 is fixed or mounted to one side of the boom 38 of the crane. Although the offset configuration may produce a bending moment in the crane boom 38, a majority of the load on the arched support guide will be transferred to the boom as an axial load. Similar to the in-line embodiment shown in FIGURE 3, the tension load is not transferred to the coiled tubing injector 18 and the wellhead. The arched support guide may be attached to the boom by a coupling that permits it to be, for example, tilted forward and backward, and to swivel, similar to the embodiment shown in FIGURE 3. However, due to the configuration of the tubing guide on the side of the boom crane, the ability of a coupling to permit swiveling could be limited by the boom 38.

FIGURE 7 illustrates an alternate embodiment in which a rotatable wheel 50 is used as a tubing support guide rather than an arched support guide 36. The rotatable wheel 50 is fixed to the head 40 FIGURE 7 of the boom 38 of the crane and is disposed generally above the boom 38. It supports the coiled tubing 34 as it changes direction from the direction it comes off from the storage reel to the downward direction where it can be received in the top of the coiled tubing injector 18. The radius of the rotatable wheel creates a sufficient arch in the coiled tubing 34 to allow the change in direction. However, the radius is great enough that the coiled tubing does not kink or otherwise damage. As with the arched support guide of FIGURE 3, the wheel 50 is attached to the boom by a coupling 46 for permitting its position or orientation to be adjusted. For example, a coupling similar to the one shown in FIGURES 4A, 4B, 5A and 5B could provide a degree of adjustability of the position and alignment of the wheel that allows some amount of freedom in terms being able to place a storage reel for the coiled tubing to one side or the other of the crane by allowing the wheel to be at an angle to the central axis of the boom of the crane. However, alternately, the wheel may be mounted in such a manner that the wheel has a fixed relationship to the central axis of the crane.

As shown in FIGURES 8A and 8B the rotatable wheel tubing guide 50 may, alternatively, be attached on one side of the crane boom 38 or other elongated support structure, such as a telescoping mast.

Referring to FIGURE 9, in another alternative embodiment, a coiled tubing guide structure can be placed on a telescoping mast, which is another example of an elongated support structure. In this example, telescoping mast 60 supports the rotatable tubing support wheel 50, illustrated in FIGURES 8 A and 8B. The rotatable wheel could also be mounted to mast 60 in a manner similar to which it is attached to crane boom 38 in FIGURE 7. Similar to the crane boom 38, the telescoping mast 60 will be subjected primarily to tensile load induced by coiled tubing 34. Neither the coiled tubing injector 18 nor the wellhead is subjected to any significant portion of the load. In certain embodiments, the telescoping mast may be mobile and mounted on a vehicle such as a trailer 62 as shown.

Reference is now made to FIGURE 10. In this embodiment, the telescoping mast 60 supports an arched support guide 36 mounted to it at its head end using coupling 46, of the type shown in FIGURE 7, for permitting it to be adjusted. In this example, it can be adjusted as described in connection with FIGURES 4A-D, or 5 A and 5B. However, the coupling could, as in the embodiment of FIGURE 3, permit adjustment in one or more degrees of freedom. In this embodiment, crane 26 is positioned opposite the telescoping mast trailer 62 and the reel 10 (which is part of coiled tubing unit 12) and supports the coiled tubing injector 18. However, it could be positioned anywhere around the wellhead. In this example, the telescoping mast 60 is used only to support and position a coiled tubing support guide, such as arched support guide 36. Γη an alternative embodiment, the injector 18 may be suspended by the mast 60 eliminating the need for the crane. It should be noted that other embodiments described and shown in this disclosure may employ a separate crane or other lifting and supporting device to support the coiled tubing injector 18, while a coiled tubing support guide is attached to a separate elongated support structure such as crane boom 38 or telescoping mast 60, whether it is an arched support guide 36 or rotatable wheel 50, like the one shown in FIGURE 7, or other type of support guide suitable for coiled tubing.

FIGURE 11 illustrates an example of relative positions of the coiled tubing unit 12 (and thus also reel 10) and the crane 26. In this embodiment, the crane 26 is positioned in front of the coiled tubing unit 12 substantially aligned with an imaginary line between the wellhead and the coiled tubing unit 12. As such, the force exerted on the crane boom 38 by the tension on the coiled tubing is in the same plane as the axis of the crane boom 38.

However, in certain oil well servicing operations, ground clearance constraints may require that the reel 10 and the crane 26 be positioned substantially side -by-side. This configuration is shown in FIGURE 12. In this configuration, a coupling such as coupling 46 may be employed to swivel the coiled tubing support guide (for example, arched support guide 36 or rotatable wheel 50). With a coiled tubing unit 12 carrying reel 10 positioned to the side of the crane, the plane of coiled tubing support guide will need to swivel up with respect to the axis of the crane boom 38. This adjustability of a coupling that permits the coiled tubing support guide to be swiveled allows the coiled tubing 34 from the storage reel 10 disposed to be properly supported by the tubing guide. Thus, the coiled tubing guide structure can be fully supported by the crane boom 38 without the crane boom 38 being aligned with the coiled tubing 34 extending upward from the storage reel 10.

Reference is now made to FIGURE 13. The illustrated embodiment is similar to that shown in FIGURE 7, with the coiled tubing unit 12 being positioned between the wellhead and the crane 26, generally along a line between the crane and the wellhead. Although wheel 50 is used as a coiled tubing support guide, an arched support guide could be employed instead.

Similarly, a telescoping mast may be employed instead of crane 26.

Reference is now made to FIGURE 14. In this example, an arched support guide 36 mounted to crane boom 38 is positioned to allow the coiled tubing unit 12 to be positioned generally opposite the wellhead from the crane boom 38. The coupling 46, attaches arched support guide 36 to the head 40 of the boom. Alternately, rotatable wheel 50 may be attached to the boom 38, or a telescoping mast 60 may be employed in place of the crane. In this example, the load induced by the tension in the coiled tubing 34 is predominately a downward bending moment on the boom 38, generally in the vertical plane of its axis if the reel 10, wellhead and crane are generally in line with each other. Referring now to FIGURES 15A-15C and 16A-C illustrate alternate embodiments of an apparatus and a method for relieving bending loads on a wellhead during conventional rigging of a coiled tubing injector on a well head. In these embodiments a bending-resistant coupling is formed between the end of the elongated support structure (for example, a crane boom, extendable mast, or similar structure) and a coiled tubing injector unit. The bending-resistant coupling forms a rigid connection from the head of the elongated support unit to the top of riser 22 once it is coupling of its two members occurs. The rigid connection, at least during expected loads, prevents tension on coiled tubing 34 from inducing a bending moment on the wellhead or substantially limiting the amount of bending to an otherwise acceptable level. However, the bending-resistant coupling in these examples permits relative rotation of a coiled tubing injector 18 with respect to the elongated support structure. During pick up and maneuvering of the coiled tubing unit toward the wellhead with the elongated support structure, the freedom of the coiled tubing injector unit to rotate with respect to the elongated support structure allows the coiled tubing injector 18, and in particular tubing support guide 16 attached to it, to maintain the same orientation with respect to reel 10.

In the two example embodiments, the bending-resistant coupling is comprised of two coupling members. An upper coupling member is connected to the elongated support structure, and a bottom coupling member is connected with the coiled tubing unit. A hoist line extending down from the elongated support structure is connected to either the bottom coupling member or the coiled tubing injector. The hoist line is used to raise the coiled tubing injector from the back of at trailer or other location in which it is being rigged for placement on top of the wellhead. When ready to be connected to the wellhead, the lower coupling member is raised into engagement with the upper coupling member. The surfaces along which the coupling members engage are, in the examples, circular in cross-section, to allow for rotation. In both embodiments, the central axis defined by the respective coupling members are coincident with each other, as well as with an axis extending from the well head 20, along the riser, to a sheave, pulley or wheel, winch, or other connection point on the head of the elongated support structure.

In the embodiment of FIGURES 15A-C cooperating or engaging surfaces of the coupling members are cylindrical, with one member fitting inside the other. The lengths of the cylindrical portions of the members are sufficient for the portions of those surfaces that engage each other when the two members are coupled to cooperate to resist substantial bending of the coupling. In the embodiment of FIGURES 16A-C bending is resisted by pulling the bottom coupling member up, using the hoist line, until complementary mating surfaces that are oblique to the central axis of each on each of the coupling members touch, and using tension on the hoist line to maintain that engagement.

During rigging, the top coupling is attached to the crane boom, mast or other elongated support member being used to move to and support over the wellhead the coiled tubing injector. The bottom coupling is connected to the coiled tubing injector when it is on the ground or trailer. The hoist line is then connected to a lift point on the bottom coupling or coiled tubing injector. At this point, the end of the elongate support member is typically much higher above the ground than the top of the coiled tubing injector. When the coiled tubing injector is ready to be positioned over the wellhead, the hoist line is used to lift the coiled tubing injector up until the bottom coupling engages or couples with the top coupling. The bottom and top coupling members will disengage when the hoist line is lowered. In these example no device or mechanism, other than the hoist line, is required to connect the two coupling members after they have been coupled. Alternately, such a device or mechanism could be used.

Referring to the embodiment of FIGURES 15A-C, coupling assembly 52 connects the coiled tubing injector 18 to the head 40 of the crane boom 34. Crane boom 34 is intended to be representative of an elongated support structure. The coupling assembly forms a rigid connection from the head 40 to the top of riser 22. The rigid connection avoids placing a bending moment on the wellhead that would otherwise result, if the coiled tubing injector 18 were allowed simply to hang form the main hoist line, from a pulling force generated by the reel 10 as it coils the tubing being wound on the drum of the reel and maintains tension on the coiled tubing 34 necessary for keeping the tubing spooled properly on the reel drum.

In this example a cylindrical member 56, made from, for example, a short length of pipe, comprises a top coupling member. The bottom coupling member is comprised of hollow cylindrical member 58, which could also be made from a length of pipe. It has inner cylindrical surface with inner diameter larger than the outer diameter of cylindrical outer surface of cylindrical member 56. When the coupling is pulled together along a central axis common to both cylindrical members, so that they at least partially overlap, at least a portion of the inner surface of hollow cylindrical member 58 surrounds and engages at least a portion of the outer surface of cylindrical member 56. Such portions will be referred to herein as an engaging surface. The cylindrical members 56 and 58 can rotate with respect to one another and translate axially with respect to one another while, as long as they remain engaged, maintaining a coupling that resists a load caused by tension on the coiled tubing that would otherwise allow bending moments on the riser 22 and wellhead 20. Note, however, that some bending may occur due to spacing between the cylinders. Such spacing might exist to allow the cylindrical members to couple and then move axially and rotationally with respect to each other.

Cylindrical member 56 is attached to the head 40 of the crane by yoke 60. In this example the yoke is attached to the ends of an extended load shaft 47 of sheave 45. However, different structures can be used to attach the cylindrical member to the crane or to a mast or other elongated support structure. Cylindrical member 58 is connected to, and supported above, a top of the coiled tubing injector 18 through a frame 62. Hoist hook 42 is connected to a hook or latch member 64 that is connected to or otherwise part of the framework. The frame 62 provides sufficient clearance to allow tubing support guide 16 to connect to the top of the coiled tubing injector 18.

In this example, the frame 62 is connected to the top of the frame 18a through a balancing mechanism that allows the position of the coiled tubing injector 18 to be shifted from side to side with respect to the lift point at which hook 42 is attached, so that the center of gravity of the coiled tubing injector unit, is directly below the lift point, thereby compensating for the weight of the tubing support guide 16 extending to one side. The balancing mechanism, in this example, allows for translational movement of the coiled tubing injector 18 with respect to the frame 62 by means of one or more tracks 66 mounted and a plurality of rollers 68. The tracks 66 are connected to frame 62 and the rollers 68 are connected to the frame 18a of the coiled tubing injector 18.

Once the coiled tubing injector unit is positioned correct, it is pinned, bolted, or otherwise fixed to the frame 62.

FIGURES 16A-C illustrate an alternate embodiment in which the bending-resistant coupling is comprised of a pair of concentric rings 70 and 72. Although the rings, in this example, have engaging surfaces that are cylindrically shaped, they are too short to provide resist bending. The rings include concentric cylindrical surfaces 70a and 72a, having a common central axis that is generally aligned vertically when the coiled tubing injector 18 is freely hanging from hook 42. The rings also present mating surfaces 70b and 72b, respectively, that are oriented at an oblique angle with respect to the cylindrical surfaces 70a and 72a. In this example, they generally lay within a plane that is perpendicular to the cylindrical surfaces 70a and 72a. When the two rings are pulled together to engage at least along the mating surfaces 70b and 72b, and then held in that position, the coupling resists bending. The concentric cylindrical surfaces70a and 72a maintain alignment of the mating surfaces, at least while they are engaged, and tend to assist with alignment during the coupling process. Alternatively, rather than having two surfaces that engage, mate or otherwise cooperate, each ring could present to the other ring a single complementary surface with which the other could engage to resist bending. This surface could, for example, be conical in shape, which would function to both guide and center the two rings, as well as provide mating surfaces that resist a bending moment on the two parts of the coupling.

Rotation is possible at least before the two rings engage, as well as after the rings engage, depending on the amount of friction. Translation movement of the two rings with respect to each other is enabled by raising and lowering the hook 42.

Hook 42 is connected to a balancing harness 76, which in turn is connected to the frame of straightener 19, which in turn is connected to the frame 18a of the coiled tubing injector unit. If no straightener is included, the balancing harness 76 would be connected directly to frame 18a of the coiled tubing injector 18. The balancing harness 76 allows the position of the coiled tubing injector 18 and straightener 19 to be moved so that its center of gravity of aligns with the lift point (the point at which hook 42 connects to the balancing harness). Frame 78 connects the lower ring 72 to the coiled tubing injector 18 or, in this example, which includes straightener 19, to the top of the frame of the straightener 19, which is in turn connected to the frame 18a of the coiled tubing unit in a fixed relationship. Yoke 80 connects the upper ring 70 to the extended load shaft 47 of sheave 45.

The embodiment of FIGURE 17 does not include a coupling and allows the coiled tubing injector 18, to which is attached tubing support guide 16, to hang in a conventional manner from main hoist line 44. An extension arm 82 mounted to the head 40, a pulley or sheave 84 mounted at one end of the arm, and a line run around the pulley or sheave. The line is connected to tubing support guide 16 to apply a force that counteracts the force from the tension on coiled tubing 34 that would induce a bending moment on riser 22 and the wellhead 20.

Referring now to FIGURE 18, in order to perform a service on an oil and gas well using the exemplary arrangements illustrated in FIGS 3-17, an elongated support structure, such as crane 26, a telescoping mast, or other structure, is transported to the site and set up in position near the well head 20, and a coiled tubing support guide is mounted to the elongated support structure. Also transported to the site are a reel of coiled tubing 10, a coiled tubing injector 18, and one or more blowout preventers, risers and other equipment and tools needed for connecting the coiled tubing injector to the wellhead, as well as power packs and controls for operating the reel and injector. Although there are many different ways and to setup this equipment to perform a service on the well, which depends in part on the type of the service to be performed, the process generally involves, in no particular order, connecting the blowout preventers and riser to the well, feeding coiled tubing from reel into the injector, over the coiled tubing support guide, and hoisting the injector in place above the wellhead using either the crane, telescoping mast or other type elongated support structure. Once the injector is connected to the wellhead and the free end of the coiled tubing is connected with a tool, the injector is then operated to run the coiled tubing in and out of the well bore, and the storage reel of coiled tubing is operated in conjunction with the injector to maintain at least a predetermined tension of the coiled tubing as the coiled tubing is being spooled on to, and unspooled from, the reel.

FIGURE 18 shows a preferred placement of the base of a crane 26 or the base of other elongated support structure with respect to the reel 10 of coiled tubing unit 12 and wellhead 20. When the coiled tubing injector 18 is initially hoisted off the back of the trailer 11 by, for example, crane 26, the position of its boom 38 is indicated by a line 88. As the coiled tubing injector 18 is maneuvered by the crane and connected to well head 20, the orientation of the boom is indicated by line 88, which is a line extending between the base of crane, where the boom attaches, and the well head. Line 90 extending between the coiled tubing reel 10 and the wellhead 20 generally indicates the path of the coiled tubing 34, and thus also the direction of the force generated by the tension on the coiled tubing. The angle 92 formed between liens 88 and 90 is, preferably not greater than 70 degrees in a first embodiment, not greater than 30 degrees in a second embodiment, and not greater than twenty degrees in a third embodiment.

The foregoing description is of exemplary embodiments. Alterations and modifications to the disclosed embodiments may be made without departing from the inventions taught by the examples. The meanings of the terms used in this specification are, unless expressly stated otherwise, intended to have ordinary and customary meaning, and are not intended to be limited to the details of the illustrated structures or the disclosed embodiments.