Patent Publication Number: US-7708058-B1

Title: Selectably elevatable injector for coiled tubing

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a selectably elevatable coiled tubing injector for a mobile self-contained unitized coil tubing rig for the drilling and workover of petroleum wells. In particular, the present invention concerns a mechanism for positioning a trailer mounted coiled tubing injector either in a first stowed position on the deck of the transport trailer or in a second position resting on an elevated rig floor of a drilling rig. 
   2. Description of the Related Art 
   Coiled tubing rigs primarily include a tubing storage reel and a coiled tubing injector for forcing a string of coiled tubing into or pulling it out of a well. Coiled tubing rigs are commonly used in the oilfield for reasons of speed and low cost operation. Due to advances in the ability to run downhole drilling motors on the lower end of a coiled tubing drill string, a need has arisen for coiled tubing injectors which can be positioned on a rig floor so that the tubing from the injector is coaxially aligned with the well bore. Previously, this need has been filled by lifting a self-contained conventional injector from a transport trailer to the rig floor using large forklift trucks, cranes, or other means. Upon completion of a job by such an injector, the injector has to be lifted back onto the transport trailer. 
   When being transported, such a conventional injector must be restrained by tiedown means, so the conventional approach involves considerable setup and rig down time, as well as necessitating lifting equipment. Additionally, the storage reel must be carefully positioned during the lifting to and from the rig floor in order to avoid damaging the tubing, particularly when the tubing is left engaged with the injector. If the tubing is released from the injector for lifting, then it must be rethreaded through the injector after the injector has been lifted. 
   Accordingly, a need exists for a coiled tubing injector which can be moved more readily between a transport trailer and a rig floor. 
   Furthermore, whenever a coiled tubing string is used to drill wells with a downhole motor, the tubing often becomes stuck in the hole due to pressure differentials between the hole and adjacent formations. Whenever this happens, it is necessary to exert considerable upward force on the tubing to free it from the well. Likewise, to retrieve packers from a well and for a variety of other downhole operations, large vertical pulls are needed. These vertical uplift forces are often in excess of what can be provided by the drive means of conventional coiled tubing injectors. 
   Thus, there is a need for a mechanism that can easily provide additional tension to a coiled tubing string beyond that which can be provided by a conventional coiled tubing injector. 
   SUMMARY OF THE INVENTION 
   This invention pertains to a selectably elevatable tubing injector for a mobile self-contained unitized coil tubing rig for the drilling and workover of petroleum wells. In particular, the present invention concerns a mechanism for positioning a trailer mounted coiled tubing injector either in a first stowed position on the deck of the transport trailer or in a second position resting on an elevated rig floor of a drilling rig. Further, the present invention provides a mechanism for selectably elevating the injector above its second position on the rig floor, while clamping onto the tubing, in order to provide additional vertical tension on the tubing string or to raise the tubing deployed within a well. 
   One embodiment of the present invention includes a positioning mechanism for a trailer mounted coiled tubing injector, the positioning mechanism comprising: (a) a coiled tubing injector support system including an injector cradle providing a framework for mounting the coiled tubing injector, wherein the injector cradle has a cradle opening wherein a portion of a drive wheel of the coiled tubing injector is rotatably housed, a frame assembly having a frame opening, wherein the injector cradle is nested within the frame opening, and a lifting mechanism for selectably elevating and lowering the injector cradle and the coiled tubing injector within the frame opening; (b) a selectably engageable coiled tubing clamp assembly mounted on a first end of the frame assembly; and (c) a swing arm assembly including a plurality of hinged support arms, wherein each support arm is attached at one end to the frame assembly and at a second end to a trailer, and a rotation device that reciprocably rotates the coiled tubing injector support system between a stowed position on the trailer and an operating position. 
   A second embodiment of the present invention includes a positioning mechanism for a trailer mounted coiled tubing injector system, the positioning mechanism comprising: (a) a coiled tubing injector support system mounted on a trailer, the injector support system including a coiled tubing injector having a rotatable drive wheel and a radially acting coiled tubing hold down mechanism, an injector cradle providing a framework for mounting the coiled tubing injector, wherein the injector cradle has a cradle opening on a top side and wherein a portion of the drive wheel of the coiled tubing injector is rotatably housed and the radially acting coiled tubing hold down mechanism sits above the injector cradle, a frame assembly having a frame opening on a top side, wherein the injector cradle is nested within the frame opening such that the drive wheel of the coiled tubing injector remains rotatable within the injector cradle and the radially acting coiled tubing hold down mechanism sits above the frame assembly, and a lifting mechanism for selectably elevating or lowering the injector cradle and the coiled tubing injector within the frame opening, wherein a first end of the lifting mechanism is attached to the injector cradle and a second end of the lifting mechanism is attached to the frame assembly; (b) a coiled tubing clamp assembly mounted on a first end of the frame assembly, wherein the coiled tubing clamp assembly has two grip blocks for selectably gripping a coiled tubing exiting the coiled tubing hold down mechanism; and (c) a swing arm assembly including a plurality of hinged support arms, wherein each support arm is attached at one end to the frame assembly and at a second end to the trailer, and a rotation device that reciprocably rotates the support arms thereby moving the coiled tubing injector support system into a stowed position on the trailer or to an operating position. 
   The foregoing has outlined rather broadly several aspects of the present invention in order that the detailed description of the invention that follows may be better understood and thus is not intended to narrow or limit in any manner the appended claims which define the invention. Additional features and advantages of the invention will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and the specific embodiments disclosed may be readily utilized as a basis for modifying or designing derivative structures for carrying out the same purposes as the invention. It should be realized by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a more complete understanding of the present invention, and the advantages thereof, reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which: 
       FIG. 1  is an oblique side view of a trailer mounted coiled tubing rig with the selectably elevatable coiled tubing injector. 
       FIG. 2  is a side profile view of the coiled tubing rig arrangement of  FIG. 1 . 
       FIG. 3  is a side profile view of the coiled tubing rig with its tubing injector elevated to rest on the rig floor of a drilling rig. For clarity, the mast and other accoutrements of the drilling platform are not shown. 
       FIG. 4  is an oblique view of the coiled tubing rig with its tubing injector resting on the rig floor of the drilling rig. 
       FIG. 5  is an oblique view of the coiled tubing injector mounted in an injector cradle. 
       FIG. 6  is a view looking towards the front of the mounting trailer showing the coiled tubing injector in its injector cradle which is in turn positioned in an intermediate frame and the gripping blocks of tubing clamp assembly in a closed, gripping position. 
       FIG. 7  corresponds to  FIG. 6 , but with the gripping blocks of the tubing clamp assembly in an open, nongripping position. 
       FIG. 8  is an oblique view of the intermediate frame which supports the tubing injector and its mounting cradle. 
       FIG. 9  is a side view of the tubing injector and its mounting cradle positioned within the intermediate frame. 
       FIG. 10  is a view towards the front of the trailer showing the tubing injector in place on the rig floor of the drilling platform, wherein the coiled tubing is shown deployed into a well and the tubing is not gripped by the coiled tubing clamp assembly. 
       FIG. 11  corresponds to  FIG. 10 , but shows the gripping blocks of the coiled tubing clamp assembly biased against the tubing and the injector mounted in its cradle elevated relative to the intermediate frame and the rig floor in order to stretch or pull the tubing upwardly from the well. 
       FIG. 12  is a partial view of the rear end of the trailer showing the coiled tubing injector in its cradle and in the intermediate frame, wherein the unit is resting on the rear deck of the trailer. 
       FIG. 13  corresponds to  FIG. 12 , but shows the tubing injector elevated for setting on a drilling rig floor by the swing arm assembly. 
       FIG. 14  is an oblique view showing the coiled tubing rig, where the coiled tubing injector is being positioned by manipulation of both a lifting line from the drilling rig and back tension from the coiled tubing storage reel. 
       FIG. 15  corresponds to  FIG. 14 , but is a side profile view. 
       FIG. 16  is an oblique detail view corresponding to  FIGS. 14 and 15 , wherein the positioning mechanism for positioning the injector is shown in more detail. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   As a note, the use of the terms “invention”, “present invention” and variations thereof throughout the subject patent application (and headings therein) are intended to refer or relate to one or more embodiments of the present application, not necessarily every embodiment or claim of the application. 
   Referring now to the drawings, it is noted that like reference characters designate like or similar parts throughout the drawings. The figures, or drawings, are not intended to be to scale. For example, purely for the sake of greater clarity in the drawings, wall thicknesses and spacings are not dimensioned as they actually exist in the assembled embodiments. 
   The structural components of the selectably elevatable coiled tubing injector are normally constructed of steel. For some purposes involving contact between the tubing and the tensioning wheel, high stiffness rubber or plastics are typically used. 
   Much of the equipment mounted on the trailer in  FIG. 1  is commercially available and is included herein only for purposes of illustrating the need for and use of the selectably elevatable coiled tubing injector. 
   For the figures herein, certain components are not shown in order to avoid overly complicating the drawings. For example, control cables, hydraulic lines, and the fluid system for feeding the reel are not shown. All of these features are well known to those skilled in the art and so they are not described herein. 
   Referring to  FIGS. 1 and 2 , an integrated trailer mounted coiled tubing rig  10  utilizing the coiled tubing injector  50  of the present invention is shown in an oblique and a side profile view, respectively. This mobile coiled tubing rig  10  is suitable for use in drilling or servicing wells. The rig  10  is shown positioned prior to having its injector  50  set up and working on a drilling rig floor  160  at a well location. The rig arrangement shown is fairly typical of commercially available coiled tubing rig layouts, with the exception of the supporting arrangements for the injector  50  and the combination of the control room  48  and the auxiliary water tank  47  into an integrated control room assembly  46 . 
   The basic elements of a trailer mounted coiled tubing rig  10  are a tractor (not shown) for pulling the trailer  20 , a rig power unit  31  fed by fuel tank  30 , a tubing storage reel  40 , a tubing injector system  50 , tubing  70 , and a control room  48 . The power source  31 , the fuel tank  30 , the tubing storage reel  40 , the tubing injector  50 , the tubing  70 , and the control room  48  are all mounted on the trailer  20 . Trailer  20  is normally of the “low boy” type, given that the tubing storage reel  40  is normally rather tall. The length of the low boy trailer is at or close to a maximum practical length for transport over the unimproved roads that frequently are the only access to well locations. The entire rig  10  is supported on surface  18 , which can be either a roadway or the surface of the ground. 
   The low boy trailer  20  has an elevated rear deck  21 , a depressed central deck  23 , and an elevated forward deck  22 . All of the deck segments  21 ,  22 , and  23  are parallel to the ground. The rear deck  21  has multiple axles with tires  26  and a suspension system (not shown) supporting it underneath. This sort of arrangement for the trailer  20  is in common use in the trucking industry. The decks  21 ,  22 , and  23  have longitudinal beams underneath which are structurally connected to the decks to provide bending strength and stiffness to the trailer  20 . 
   Selectably axially reciprocable stabilizing jacks  28  are located at the forward outboard corners of the central deck  23  and the rear outboard corners of the rear deck  21  of the trailer  20 . These jacks  28  are extended to firmly engage the surface  18  when the trailer  20  is positioned ready to service a well. The jacks  28  are used so that the trailer  20  is stabilized as the amount of tubing  70  on the tubing storage reel  40  changes or and/or the injector is moved thereby shifting the load on the trailer. In addition, the loads on the trailer  20  and its jacks  28  will change whenever the tension changes on the tubing  71  adjacent the wellhead. 
   The fuel tank  30  is located adjacent the forward end of the central deck  23 , and the power unit  31  is located slightly to the rear of the fuel tank. The fuel tank  30  is mounted on a pair of pedestals and is a standard cylindrical tank with elliptical ends. The fuel tank  30  provides a sufficient supply of fuel to operate the power unit  31  for a period long enough to complete most jobs without refueling. The power unit  31  drives one or more hydraulic pumps and an electrical generator to power the reeling and tensioning of the coiled tubing  70  and other functions of the trailer mounted rig  10 . 
   The tubing storage reel  40  is a large device which stores a sufficient amount of steel tubing  70  to permit reaching the bottom of the wells for which the rig  10  is capable. The tubing storage reel  40  both pays out and retrieves the tubing  70 , although most of the tension or compression in the tubing string is provided by the injector  50 . The location of the tubing storage reel  40  is on the central deck  23  to the rear of the power unit  31  and forward of the rear deck  21  of the trailer  20 . Levelwinding of the tubing  70  is required to achieve compact storage and avoid overstressing the tubing  70  where wraps of tubing cross each other. The hub of the reel  40  has a diameter sufficiently large that repetitive bending cycles of the tubing  70  will not prematurely fatigue the tubing. The tubing  70  coiled on the reel  40  is laterally constrained between opposed side flanges. 
   The reel  40  has a horizontal shaft which provides a rotational axis which is transverse to the longitudinal vertical midplane of the trailer  20 . The shaft is supported by a large pillow block bearing on each side, while the pillow blocks are in turn supported on a pedestal  41 . The pedestal  41  consists of a pair of trapezoidal vertical spaced apart slabs parallel to the sides of the trailer  20  and joined by a rectangular base plate. The width of the pedestal  41  is approximately half of the width of the trailer  20 . The base plate of the pedestal  41  extends a short distance forward of the forward edge of the pedestal slabs. The two slabs of the pedestal  41  each have a transverse forward and rear through hole parallel to and slightly above the base plate. The forward holes are mutually coaxial, as are the rear holes. 
   A large driven chain sprocket is mounted on the reel shaft on the lefthand side of the reel  40  so that the reel can be rotated bidirectionally by its drive chain. The drive chain is bidirectionally driven in turn by a small chain sprocket mounted on the output shaft of the hydraulic motor of hydraulic motor assembly. A hydraulic motor is mounted on a mounting base for the hydraulic motor assembly rigidly attached to the upper surface of the forward extension of the pedestal  41  so that the chain sprockets are in alignment. 
   A double acting hydraulic levelwind actuation cylinder selectably controlled from the control room assembly  46  has its cylinder body mounted transversely in a horizontal position to the upper surface of the central deck  23  of the trailer. The rod end of the levelwind actuation cylinder is attached to the middle of the base plate of the pedestal  41  on its rear vertical side. The pedestal  41  of the tubing storage reel  40  is supported slightly above the central deck  23  of the trailer  20  on a pair of tubular horizontal transverse guide rails engaged in the transverse holes at the bottom of the slabs of the pedestal. 
   Each of the two transverse guide rails is mounted by a pair of end blocks, with the outside transverse face of each end block flush with its respective side of the trailer  20 . The combination of the length of the transverse guide rails  45  and the width between flanges of the reel  40  is selected so that system operator can controlled lateral shifting of the position of the reel by the levelwind actuation cylinder, thereby causing the coiled tubing  70  to properly nest on the reel. 
   The control room assembly  46  is positioned on the forward deck  22  of the trailer  20 . The control room assembly  46  consists of an auxiliary tank  47  and the control room module  48 . For travel, the control room module  48  is nested within the tank  47 , but the control room can be selectably elevated to its upper position so that a human operator positioned there can more readily observe the general operation of the coiled tubing rig  10  and, particularly, the level winding of tubing  70  onto the storage reel  40 . Alternatively, a more conventional control room arrangement can also be used satisfactorily. 
   The tubing injector system  50  is mounted on the longitudinal centerline of the rear deck  21  of the trailer  20 . Although a variety of tubing injectors are suitable for use, the particular tubing injector shown here is a reversible wheel type injector and is used to apply the primary tractive loads to the tubing  70  to urge the tubing into or out of the well. Often a well servicing job requires that the tubing  70  be forcefully injected through a blowout preventer device  150  which seals between the wellhead and the portion of the tubing  71  which is entered within the well bore. Likewise, frequently the weight of the tubing  71  in the well exceeds the axial pressure load applied to the tubing, requiring tractive force to lift the tubing from the well. 
   Referring to  FIG. 5 , the tubing injector system  50  consists of a drive wheel  55  mounted on a pair of pillow block bearings  52  and driven by a hydraulic motor assembly  54  engaging a drive chain  53 . A structure supporting a series of coacting radially inwardly urged rollers constitutes a radially inwardly acting holddown mechanism  57 . 
   The drive wheel  55  has two parallel circular side plates connected by a cylindrical annular ring set inwardly a short distance from their outer circumference. An array of multiple closely spaced support blocks  66  are fitted to the annular ring on their inward side and have an annular groove in the center of their outer side. Through bolts with nuts parallel to the wheel axis penetrate the side plates and the support blocks to provide support to the tubing  70  in the groove of the support blocks. 
   The drive wheel  55  has an axial horizontal shaft coaxially attached to the side plates which provides a rotational axis transverse to the longitudinal vertical midplane of the trailer  20 . The shaft is supported by a large bearing pillow block  52  on each side, while the pillow blocks are in turn supported on the upper surface of the injector cradle assembly  81  of the tubing injector support system  80 . 
   A large drive chain sprocket  56  is mounted on the shaft on the lefthand side of the drive wheel  55  so that the wheel can be rotated bidirectionally by drive chain  53 . Drive chain  53  is bidirectionally driven in turn by a small chain sprocket mounted on the output shaft of the hydraulic motor of hydraulic motor assembly  54 . The hydraulic motor is mounted on a mounting base for the hydraulic motor assembly  54  which is in turn rigidly attached to the upper surface of the injector cradle  81  so that the chain sprockets are in alignment. 
   The tubing injector system  50  is provided with a radially inwardly acting holddown mechanism  57  which serves to force the tubing  70  engaged around the drive wheel inwardly against the tubing support blocks  66  of the drive wheel  55 . This radially inward forcing ensures high frictional forces can be developed between the drive wheel  55  and the tubing  70 , regardless what the tension in the tubing is. The radially acting holddown mechanism  57  is coaxially structurally supported on the shaft of the drive wheel by a holddown support frame  59  consisting of two nonrotating mirror image reinforced plate arcuate sectors which straddle drive wheel  55 . The holddown support frame  59  is prevented from rotating by two mirror image antirotation braces  67  which connect between the support frame  59  and the upper surface of the injector cradle  81 . 
   The radially inward holddown reaction on the tubing  70  in the groove of the tubing support blocks  66  of the drive wheel  55  is provided by a set of circumferentially spaced apart parallel centrally grooved tubing rollers having axes parallel to the drive wheel and engaging the coiled tubing  70  over its arc of contact with the drive wheel. The tubing rollers are mounted on radially movable holddown roller assemblies  63  which are retained and guided within radial slots on the outer peripheral inward faces of the arcuate plate sectors of the holddown support frame  59 . The radial slots are formed by circumferentially spaced apart guide plates  60  attached to the periphery of the opposed inward facing arcuate plates of the holddown support frame  59 . 
   Each holddown roller assembly  63  has a pair of static sheaves  62  located adjacent each of its opposed distal ends. Static sheaves  62  are located on both outer sides of the arcuate plate sectors of the holddown support frame  59  inwardly from the periphery, with each static sheave mounted on the radial center plane of each guide plate  60  so that a static sheave straddles each radial guide slot. Each of the holddown roller assembly end sheaves  64  has its shaft parallel to the shafts of the static sheaves  62 . Additionally, on each side of the holddown support frame  59 , the grooves of the end sheaves  64  are coplanar with the grooves of the static sheaves. 
   On each side of the holddown mechanism  57 , a single pulldown cable is anchored by a cale anchor  61  adjacent the bottom end of the array of static sheaves  62  and tensioned on its opposed end by a hydraulic tensioning cylinder  58 . The hydraulic tensioning cylinders  58  are mounted on the upper end of the radially acting holddown mechanism  57  approximately tangentially to the rim of the drive wheel  55 . The tensioning cables  65  are engaged alternately in the direction towards their tensioning hydraulic cylinders by the static sheaves  62  and the holddown roller assembly end sheaves  64 . The net reaction force on each tubing roller of the holddown roller assemblies  63  is thus radially inward. This radially inward force enhances the frictional forces between the drive wheel  55  and the tubing  70 , thereby permitting the tubing to be engaged only over a relatively small arc of the drive wheel in order to develop any necessary frictional tractive force. 
   As best seen in  FIGS. 5 through 7 , the coiled tubing injector system  50  is mounted in an injector cradle assembly  81 . The injector cradle  81  has a space frame  82  constructed primarily of square or rectangular tubing and provided with lift cylinders  84  and guide rollers  88 ,  89  and a clamp assembly  90 . The space frame  82  has two mirror image trussed panel sides, a horizontal trussed panel bottom, and a trussed panel forward end. The lower portion of the rear side of the space frame  82  is spanned by a clamp assembly  90  which is supported on a mounting plate  91 , while the upper portion of the rear side of the space frame is open. 
   The width of the space frame  82  is the same as the spacing between the pillow block bearings  52  of the coiled tubing injector  50 . The length of the space frame  82  is sufficient to mount the coiled tubing injector  50  so that its motor assembly  54  is supported at the front end and the vertical tangent to the drive wheel  55  is slightly to the rear of the rear end of the space frame. The height of the space frame  82  is such that when the coiled tubing injector  50  is mounted on the space frame, a small clearance will exist between the bottom panel of the space frame and the outer rim of the drive wheel  55  of the coiled tubing injector  50 . 
   The upper horizontal chord of each side panel is provided with two outwardly projecting horizontal rectangular prismatic ears  83 , with one ear near the forward end of the frame  82  and the other near the rear end of the frame. Each ear  83  has a central vertical tapped hole which is engaged by the male threaded rod end of the lift cylinder rod  86  of a hydraulic lift cylinder  84 , with the bodies  85  of the lift cylinders below the ears. 
   A horizontal transverse cross bar joins the upper horizontal chords of the space frame  82  a short distance to the rear of the front panel of the space frame  82 . This cross bar, along with the top chord of the front panel, serves as a support for the hydraulic drive motor assembly  54  used to activate the drive wheel  55  of the coiled tubing injector  50 . Each side panel has a pillow block mounting pad projecting upwardly on its upper horizontal chord slightly to the rear of midlength of the space frame  82 . The pillow block bearings  52  for the coiled tubing injector  50  are mounted there. A vertically upwardly extending plate lifting eye  100  is located flush with the side panel outside face and at approximately midlength of the upper horizontal chord of each side panel. 
   A short distance to the rear of the rear cylinder mounting ear  83  on each of the side panels of the space frame, a vertical structural guidance angle  87  is rigidly mounted with one leg of the angle projecting forward and flush with the outside of its side panel and with the other leg of the angle extending transversely outwardly. An intermediate vertical side frame member  92  is located between the rearward cylinder attachment ear  83  and the guidance angle  87  in each space frame  82 . 
   On each side of the space frame  82 , a horizontal axis bracket mounted lateral restraint roller assembly  88  is mounted at the bottom end of each intermediate vertical side frame member positioned between the rearward cylinder attachment ear  83  and the guidance angle  87 . The axes of the lateral restraint rollers  88  extend fore and aft and are positioned outboard of the side frames. On each side of the space frame  82 , a horizontal axis bracket mounted longitudinal restraint roller assembly  89  is mounted at the bottom end of the transversely outwardly extending leg of the structural guidance angle  87  on that side so that the axis of the roller is to the rear of the angle. 
   On the forward end panel of the space frame  82 , a horizontal axis longitudinal restraint roller assembly  89  is mounted at the intersection of the bottom chord of the front panel and each side panel so that the axes of the rollers are forward of the lower chord of the front panel. At the lower forward corner of each side panel of the space frame  82 , a horizontal axis lateral restraint roller assembly  88  is mounted with its axis outboard of the outer side of the panel. The lateral restraint roller assemblies  88  are similar to or identical to the longitudinal restraint roller assemblies  89 . 
   Referring to  FIGS. 5 ,  6 , and  7 , the clamp assembly  90  consists of mounting plate  91 , a pair of clamp hydraulic cylinders  94 , a pivot pin  95  for each cylinder  94 , a pair of mirror image clamp support blocks  96  with each containing a grip block  97 , a pair of clamp support block pivot pins  98 , and a pair of clamp cylinder rod end pins  99 . The mounting plate  91  of the clamp assembly  90  is a transversely extending thick rectangular plate lapped onto and spanning between the side panels of the space frame  82  of the injector cradle  81  of the tubing injector support system  80 . The mounting plate  91  is positioned slightly above the bottom side of the rear face of the space frame  82 . 
   The upper corners of the mounting plate  91  each have a horizontal through drilled and tapped hole extending parallel to the side panels of the space frame  82 . These drilled and tapped holes serve to mount the pivot pins  95  for the eye brackets located at the blind ends of the cylinder bodies of the double acting single rod clamp cylinders  94 . Another pair of mirror image drilled and tapped horizontal through holes are spaced apart by approximately 30 percent of the width of the mounting plate  91  approximately one third of the height of the mounting plate down from its upper edge. This second pair of holes serves to mount the clamp support block pins  98 . The pivot pins  95  for the cylinders  94  are typically headed bolts having large diameter shanks and distal end threads which are threadedly engaged with the outer upper corner tapped holes of the mounting plate  91 . The clamp support block pins  98  are generally hex head bolts having large diameter shanks and distal end threads threadedly engaged with the central tapped holes of the mounting plate  91 . 
   The clamp support blocks  96 , which are best seen in  FIG. 5  in an oblique view, are mirror image pieces which each have an elongated planar mounting plate onto which is integrally mounted a heavy U-shaped channel member. Each planar mounting plate has a through hole for journaling the shank of a clamp support pin  98  and has its channel radially spaced outwardly from its through hole. The trough of a channel extends parallel to and offset from the plane of its planar mounting plate. The flanges of each channel have a pair of through holes on their rear flange and a pair of tapped through holes on the forward channel leg. Each rear flange through hole is coaxial with a tapped forward hole. 
   The back of each channel is perpendicular to its mounting plate and approximately coplanar with the through hole in the planar mounting plate of each clamp support block  96 . A vertical integral swing arm projects on the vertical plane of symmetry of the channel back on the section of the channel distal from the pivot pin hole. The swing arms are parallel to and offset from the planar mounting plates. Each swing arm extends in a direction opposed to the legs of its channel and has a through hole parallel to the through hole in the mounting plate of the clamp support block  96 . The through hole in each swing arm is engaged with and journals a screw with a cylindrical shank and distal male threads which serves as a rod end pin  99  for the clamp cylinder  94 . The rod end of the clamp cylinder  94  is provided with a female rod eye knuckle having a tapped hole transverse to and intersecting the longitudinal axis of the cylinder. The rod end pin  99  of each cylinder  94  is threadedly engaged with the tapped hole of the female rod eye knuckle. 
   The grip blocks  97  of the clamp assembly  90  are rectangular cross section blocks which are mounted in the channels of the clamp support blocks  96 . The grip blocks  97  have circular cross section grooves which are a close fit to the tubing  70 . The depth of a groove is approximately 40 percent of the diameter of the tubing, and the groove runs in the middle of one side of the grip block. The grip block cross section is a close fit to the inside faces of the channel of a clamp support block, and the length of the grip block is the same as the length of its mounting channel. The grip blocks  97  extend slightly outwardly from the channels. Transverse through holes parallel to the grooved face of the grip blocks  97  are coaxial with the holes in the flanges of the channels of the clamp support blocks  96  so that bolts can be extended through those holes and the corresponding holes in the grip blocks in order to retain the grip blocks. 
   The clamp support blocks  96  with their integrally mounted grip blocks  97  are pivotable about their clamp support block pins  98  when the cylinders  94  are actuated. The cylinders  94  are operated in parallel by a single valve (not shown). The extension of the cylinders  94  causes the clamp support blocks  96  to jointly pivot about their clamp support pins  98  as seen in  FIG. 6 . Similarly, the retraction of the cylinders  94  causes the clamp support blocks  96  to move apart as shown in  FIG. 7 . The relative positioning of the grooves of the grip blocks  97  and the vertically extending coiled tubing section  71  deploying into a well is such that the midplanes of the grooves are coplanar with the axis of the vertical tubing section. 
     FIG. 8  shows an oblique view of the intermediate frame assembly  110  of the tubing injector support system  80 . The intermediate frame assembly  110  supports the injector cradle assembly  81  which in turn supports the coiled tubing injector  50 . The intermediate frame  110  consists of a space frame  111  constructed primarily of square or rectangular tubing and provided with guide rollers  118  and  119 . The space frame  111  has two mirror image trussed panel sides, a horizontal trussed bottom panel, and a transverse trussed forward end panel at the forward end  112  of the space frame. The trussed forward end panel has two vertical tubular members set inwardly from the side panels by a short distance and a single diagonal between those verticals. The rear side of the space frame  111  is open except for a transverse horizontal member of the bottom panel. 
   The width of the space frame  111  is sufficiently large that the interior faces of its side frames will have a fit with the lateral restraint rollers  88  of the injector cradle  81  such that the rollers can readily guide the vertical movement of the injector cradle relative to the intermediate frame  110 . The length of the space frame  111  is slightly less than that of the injector cradle assembly  81 . The height of the space frame  111  is such that when the injector cradle  81  is mounted within the space frame and reciprocated vertically to its highest position by the lift cylinders  84 , enough of the cradle  81  is retained within the intermediate frame to ensure stability under operating loads. 
   The lower horizontal chord of each side panel of the intermediate space frame  111  is provided with two inwardly projecting horizontal rectangular prismatic ears which serve as lift cylinder mounting pads  114 , with one ear near the forward end of the frame and the other near the rear end of the frame. The spacing between the lift cylinder mount pads  114  on each side frame panel is the same as that for the lift cylinder rod attachment ears  83  of the injector cradle  81 . Each lift cylinder mounting pad  114  has a central vertical through hole which journals a machine screw (not shown) which can be threadedly engaged with a tapped mounting hole on the blind end of a lift cylinder  84  to rigidly attach the cylinder body of a lift cylinder to the upper surface of the lift cylinder mounting pad. 
   A short distance to the rear of the rear cylinder mounting pad  114  on each of the side panels of the space frame, two coaxial segments of a first pair of vertical structural guidance angles  115  are rigidly mounted with one leg of the angles projecting to the rear flush with the inside face of its side panel and with the other leg of the angles extending transversely outwardly. These first angle  115  segments are cut so that each one has one end attached to a horizontal chord and the other end attached to an adjacent diagonal of its side panel. 
   A short distance to the rear of the front transverse panel of the space frame  111  on each of the side panels of the space frame, two coaxial segments of a second pair of vertical structural guidance angles  115  are rigidly mounted with one leg of the angles projecting to the rear flush with the inside face of its side panel and with the other leg of the angles extending transversely outwardly. These second angle  115  segments also are cut so that each one has one end attached to a horizontal chord and the other end attached to an adjacent diagonal of its side panel. 
   A short distance to the rear of the first set of guidance angles  115  is a third pair of guidance angles. For the third pair, on each of the side panels of the space frame  111 , a vertical structural guidance angle  115  is rigidly mounted with one leg of the angle projecting to the rear and flush with the inside of its side panel and with the other leg of the angle extending transversely inwardly. The forward transverse faces of the third pair of guidance angles  115  are flush with the rear transverse horizontal cross member of the bottom frame panel. 
   Each side panel of the space frame  111  has a pair of horizontally outwardly projecting cylindrical pivot arm mounting bosses  116  on its upper horizontal chord. The first boss  116  of the pair on a side panel is located at the forward end  112  of the space frame  111 , while the second boss is located approximately 65 percent of the length of the space frame to the rear. Each boss  116  has a tapped centrally located transverse horizontal hole for threaded engagement with an arm end pin  129  so that either a first  126  or second  127  swing arm can be pivotably mounted there as shown in  FIG. 12 . 
   On each side of the space frame  111  of the intermediate frame assembly  110 , a horizontal axis bracket mounted lateral restraint roller assembly  118  is mounted at the upper end of each first pair of vertical guidance angles  115 . The axes of the lateral restraint rollers  118  extend fore and aft and are positioned inboard of the side frames. The spacing between these opposed lateral restraint rollers  118  is such that they can bear on and freely roll on the outwardly facing planar vertical face of the intermediate vertical side members  92  of the injector cradle  81 . 
   On each side of the space frame  111 , a horizontal axis bracket mounted longitudinal restraint roller assembly  119  is mounted at the upper end of the transversely inwardly extending leg of the third structural guidance angle  115  on that side so that the axis of the roller is to the front of the angle. The lateral restraint roller assemblies  118  are similar to or identical to the longitudinal restraint roller assemblies  119 . The spacing between these longitudinal restraint roller assemblies  119  is such that the rollers bear on the rear face of the vertical guidance angles  87  of the injector cradle  81 . 
   On the forward end panel of the space frame  111 , a horizontal axis longitudinal restraint roller assembly  119  is mounted on the rear face of the top chord of the front panel so that the axes of the rollers are to the rear of the upper chord of the front panel. The spacing of the roller assemblies  119  is such that the rollers can bear on and freely roll on the front face of the forward vertical members of the side frames of the injector cradle  81  when that cradle is positioning within the intermediate frame assembly. 
   A few inches to the rear of the front frame panel of the space frame  111 , two opposed horizontal axis lateral restraint roller assemblies  118  are mounted with their axes inboard of the inner sides of their respective side frame panels. When the injector cradle  81  is positioned in the intermediate frame assembly  110 , the spacing between these opposed lateral restraint rollers  118  is such that they can bear on and freely roll on the outwardly facing planar vertical face of the second (forward) pair of vertical guidance angle segments  115 . 
   The positioning of the forward longitudinal restraint rollers  89  of the injector cradle  81  is such that they bear on and roll on the rear face of the inwardly set vertical members in the front frame panel of the space frame  111  of the intermediate frame assembly  110 . The positioning of the third (rear) pair of vertical guidance angles  115  of the intermediate frame  110  is such that the rear longitudinal restraint rollers  119  of the injector cradle  81  bear on the forward vertical faces of those angles. 
   The location of the second (forward) pair vertical guidance angle segments  115  is such that the forward lateral restraint roller assemblies  88  of the injector cradle bear on and roll on the inner face of those angle segments  115 . The location of the first (rear) pair of vertical guidance angle segments  115  is such that the rear lateral restraint roller assemblies  88  of the injector cradle  81  bear on and roll on the inner face of those angle segments  115 . 
   Accordingly, the location in the horizontal plane of the injector cradle  81  relative to the intermediate frame  110  is closely controlled by the restraint roller assemblies  88 ,  89 ,  118 , and  119  when the lift cylinders  84  vertically reciprocate the injector cradle  81  within the intermediate frame  110 .  FIG. 9  illustrates a side view of the intermediate frame assembly  110  housing the injector cradle  81  in its lower position. 
   The swing arm assembly  125 , best seen in  FIG. 12  in its lower position and  FIG. 13  in its upper position, consists of a pair of first arms  126 , a pair of second arms  127 , arm end pins  129 , four arm pedestals  130 , a pair of cylinder bases  133 , and a pair of swing cylinders  134 . The first  126  and second  127  swing arms are similar rectangular constant cross section tubular members having parallel horizontal axis through pivot holes at their ends. Both the first  126  and second  127  swing arms have the same length and distance between their pivot holes, but the first swing arms  126  also have a boss with a through hole parallel to their distal pivot holes on their lower sides positioned approximately 40 percent of the arm length from the pivot holes on their lower ends. 
   The arm end pins  129  are large bolts with cylindrical shanks which are close fits to the distal pivot holes of swing arms  126 ,  127 . The upper four of the arm end pins  129  are journaled in the upper end pivot holes of the swing arms  126 ,  127  and have distal male threads which are threadedly engaged with the tapped holes in the cylindrical pivot arm mounting bosses on the outer sides of the intermediate frame  110 . 
   Two identical arm pedestals  130  are located on each side of the rear deck  21  of the trailer  20 . An arm pedestal  130  consists of a vertical main plate with a shorter central transverse vertical stiffening plate welded to the outboard side of the main plate. The main plate and the stiffening plate have coplanar horizontal bases, and the upper end of the main plate has a central transverse through hole which has tapped threads comatable with the distal threads of an arm end pin  129 . 
   The forward arm pedestals  130  are mounted to the rear deck  21  with their tapped holes coaxial and their main plates equally offset from the centerline of the rear deck so that their main plates are parallel to the trailer centerline with their stiffening plates on their outboard sides. The rear arm pedestals  130  are positioned to the rear of the forward arm pedestals and mounted similarly. The spacing between the tapped holes at the upper ends of the forward and rear arm pedestals and the distance between the outer faces of the main plates of the opposed arm pedestals  130  is the same as the distance between the pivot arm mounting bosses  116  of the intermediate frame assembly  110 . 
   The pivot holes, at the lower end of each of the first swing arms  126  and the second swing arms  127 , journal arm end pins  129  which are threadedly engaged in the tapped holes of the arm pedestals  130 . Thus, both first swing arms  126  and both second swing arms  127  are all mutually parallel. Because the first and second swing arms  126 ,  127  have the same length and are always parallel, the intermediate frame assembly  110  is always parallel to the rear deck  21  of the trailer  20 . 
   The cylinder base  133  is a long rectangular prismatic box with integral opposed devises for mounting of the swing cylinders  134 . The cylinder base is symmetrically transversely mounted on the central deck  23  of the trailer  20  and is itself symmetrical about the longitudinal midplane of the trailer. The cylinder base  133  extends across most of the width of the central deck. Each clevis on the upper side of the cylinder base consists of two parallel spaced apart vertical plates having coaxial through holes which are perpendicular to the longitudinal midplane of the trailer  20 . The gap between an adjacent pair of plates in the devises is a loose slip fit to the mount  139  of the swing cylinder body  135  of the swing cylinder  134 . The spacing between the devises of the cylinder base  133  is such that the lateral spacing of the axes of the swing cylinders  134  is the same as the spacing between the opposed first swing arms  126 . 
   The two swing cylinders  134  are substantially identical double acting hydraulic cylinders, each with a rod clevis  137  having a clevis pin  138  on the distal end of its cylinder rod  136 . The mounting of the body  135  of a swing cylinder  134  is provided by a swing cylinder mount  139  having mirror image horizontally transversely extending external upsets located close to the blind end of the cylinder body  135 . The outer ends of the upsets are vertical and have central tapped horizontal holes with axes intersecting the longitudinal axis of their cylinder  134 . The width of the swing cylinder mount  139  is such that it is a close slip fit between a pair of adjacent clevis plates on the cylinder base  133 . 
   A pair of opposed bolts serve as an opposed pair of swing cylinder body pivot pins  140 . For each swing cylinder  134 , the swing cylinder body pivot pins  140  have their shanks journaled in the pivot holes of an adjacent pair of clevis plates of the cylinder base  133  and threadedly engaged with the female threads of the swing cylinder mount  139 . Thus, the swing cylinder bodies  135  are pivotably mounted near their blind ends about the clevises of the cylinder base  133 . Each swing cylinder  134  has its rod clevis connected by a rod clevis pin  138  to the transverse hole in the intermediate boss on the lower side of its first swing arm  126 . 
   The swing cylinders  134  are actuated to extend or retract by pressured hydraulic fluid from the hydraulic system (not shown) of the coiled tubing rig  10  and controlled from the control room  48  by means of a four-way three position hydraulic valve. Reciprocation of the swing cylinders  134  causes the swing arm assembly  125  to move the intermediate frame assembly  110  with its attached injector cradle  81  in an arc between a traveling position on the rear deck  21  of the trailer  20 , shown in  FIG. 12 , and an elevated position, shown in  FIG. 13 . 
   Referring to  FIGS. 3 ,  4 ,  10 , and  11 , the coiled tubing rig  10  with the tubing injector support system  80  of the present invention is seen set up on a well location at which a drilling rig is present. For clarity in description, the drilling mast  164 , drawworks  165 , and crown block assembly  166  are not shown for these figures. These rig items and other equipment associated with the drilling rig are familiar to those skilled in the art, so the description herein is limited. The well is provided with a blowout preventer assembly  150  mounted on its wellhead. The substructure  161  of the rig straddles the wellhead and preventer  150  and supports a rig floor  160  above the preventer. A rotary table  162  is positioned on the rig floor  160  coaxially with the well bore. The coiled tubing rig  10  has its tubing deployed into the well, with the tubing section between the injector  50  and the well designated by numeral  71 . 
     FIGS. 14 ,  15 , and  16  describe a coiled tubing rig  10  having an alternative lifting means for the movement of the swing arms  126  and  127  with the attached tubing injector support system  80 . Here the movement of the swing arms  126  and  127  is effected by using a lifting line  169  which is controlled by the rig drawworks  165  and is dependent from the crown block assembly  166  mast  164  of the drilling rig. 
   Whenever the lifting line  169  is used as the lifting means for the swing arm assembly  125 , a central pad eye on the upper side of a horizontal spreader bar  170  is attached to the free end of the lifting line  169 . Lifting line  169  is dependent from the crown block assembly  166  at the upper end of the rig mast  164  and is wound around the drum of the drawworks  165  of the drilling rig. Mirror image spreader rods  171  or cables are attached at their upper ends to the distal ends of the spreader bar  170 . At their lower ends, the opposed spreader rods  171  have clevises which are attached by spreader clevis pins  172  to the lifting eyes  100  on the upper chords of the side frames of the cradle space frame  82  of the injector cradle assembly  81 . Whenever it is desired to move the tubing injector support system  80  in either direction between its first stowed position on the rear deck  21  of the trailer or its second position on the rig floor  160 , the tubing is clamped by the clamp assembly  90 . 
   Rather than using the hydraulic system of the coiled tubing rig  10  to actuate the swing cylinders  134  and thereby raise or lower the tubing injector support system  80 , the cylinders  134  can either serve as hydraulic dampers or be replaced by commercially available hydraulic dampers. Using the conventional swing cylinders  134  as dampers is done either by installing one or more restrictive orifices in each of the piston heads of the cylinders  134  or by interconnecting the two extreme ends of each cylinder cavity of the individual cylinder bodies  135  by means of a connecting line having an in-line restrictive orifice. Either of these approaches provides the functional equivalent of a commercially available hydraulic damper. 
   OPERATION OF THE INVENTION 
   The operation of the tubing injector support system  80  of the coiled tubing rig  10  proceeds as described below. The trailer  20  supporting the coiled tubing rig is delivered to the well location in the configuration shown in both  FIGS. 1 and 2 . Typically, the tractor rig used for towing the coiled tubing rig  10  would be attached throughout the job, but the tractor is not shown herein for reasons of clarity. 
   To begin the job setup, the trailer  20  is backed up towards the drilling rig so that the midplane of the trailer  20  intersects the vertical axis of the well. When the trailer  20  is in its approximate position for swinging the intermediate frame assembly  110  with its injector cradle  81  and injector  50  up onto the rig floor  160 , the jacks  28  supporting the trailer  20  are set to bear against the ground surface  18  so that the trailer is stabilized. Following this, the control room module  48  is elevated to its working position and the operator occupies the control room. The lift cylinders  134  are extended then by the coiled tubing rig operator so that the intermediate frame  110  is swung upwardly and towards the rig floor  160 . 
   While the intermediate frame  110  is being raised or lowered by the lift cylinders  134 , the clamp assembly  90  on the injector cradle  81  is used to clamp and immobilize the free end  72  of the tubing string  70 . The operation of the clamp assembly  90  is discussed in the material below. During lifting of the tubing injector support system  80 , the storage reel  40  is allowed to freewheel so that the tubing  70  is tensioned only by reel turning friction between the reel and the injector  50 . During lowering of the tubing injector support system  80 , the reel  40  is rotated so that excess tubing length between the reel and the injector  50  is retrieved onto the reel. 
   The length of the swing arms  126  and  127  is preselected to ensure that the intermediate frame  110  can reach the rig floor  160 . After the swing arms  126  and  127  pass vertical, the intermediate frame  110  is lowered so that it rests on the rig floor. Counterbalance valves are used in the hydraulic control circuit for the lift cylinders  134  to prevent the sudden dropping of the tubing injector support system  80  when that system is being lowered in either direction. 
   If the free end  72  of the coiled tubing string  70  is not concentric with the well bore, the error is measured, the intermediate frame assembly  110  is lowered, the jacks  28  raised, and the trailer is moved to correct the trailer placement error. The jacks  28  are again lowered and the intermediate frame assembly  110  is again elevated so that the free end  72  of the coiled tubing string  70  can be entered coaxially into the well. The injector  50  can then be used to insert tubing  70  into or retract it from the well. 
   In the event that the tubing string  71  in the well becomes stuck or it is being used to pull a packer from the well, then it can be necessary to exert more tension on the tubing than can be provided by the rotational drive means of the injector  50 . In such a case, the following procedure is used. 
   The initial, lower position of the injector cradle  81  relative to the intermediate frame  110  is shown in  FIG. 10 . First, the tubing is clamped by extending the previously retracted clamp cylinders  94  of the clamp assembly  90  of the injector cradle  81  so that the clamp support blocks  96  supporting the grip blocks  97  are rotated about their clamp support block pins  98 . The extension of the clamp cylinders  94  is continued until the tubing section  71  between the drive wheel  55  of the injector  50  and the blowout preventer  150  is firmly gripped between the grip blocks  97 . The positions of the components of the clamp assembly  90  when clamping are shown in  FIG. 11 . 
   When the tubing section  71  deployed into the well is gripped at its upper end, then pressurized hydraulic fluid is directed to extend the four lift cylinders  84  by a selectably operable four-way three-position closed-center control valve. The longitudinal restraint roller assemblies  89  and  119  and the lateral restraint roller assemblies  88  and  118  centralize the injector cradle  81  within the intermediate frame  110  during raising and lowering. This raising of the injector cradle  81  with its clamped integral clamp assembly  90  gripping the upper end of the clamped tubing produces additional tension in the tubing section  71 .  FIG. 11  shows the injector cradle  81  in its position when fully raised by the lift cylinders  84 . 
   In the event that this additional tension is insufficient to free the tubing or the packer, standard oilfield coiled tubing slips (not shown) can be used to hold the tubing  71  temporarily at the rotary table  162  while the clamp assembly  90  is released from the tubing  71  by retracting the clamp cylinders  94 . The injector cradle  81  then can be lowered by the lift cylinders  84  preparatory to reclamping the tubing  71  for another lifting cycle to further tension the tubing  71 . If the tubing section  71  is freed, then the injector cradle  81  can be lowered while the injector  50  and the tubing reel are rotated to retrieve the slack in the tubing. Further operations of the coiled tubing rig are then free to proceed as necessary. 
   When the job is complete, all of the tubing section  71  is pulled from the well and the clamp assembly is used to clamp the free end  72  of the tubing string  70 . The tubing injector support system  80  can then be lowered to the rear deck  21  of the trailer  20  by retracting the swing cylinders  134  while the storage reel  40  is rotated to retrieve the excess tubing  70  between reel and the injector  50 . The jacks  28  for the trailer of the coiled tubing rig  10  are then raised and the control room  48  lowered to its travel position. At this point, the coiled tubing rig is again roadworthy. 
   Alternatively, the swing cylinders  134  with restrictive orifices (or the equivalent commercially available hydraulic dampers) only provide motion damping when the tubing injector support system  80  is raised or lowered by cooperative manipulation of the tubing reel  40  and a lifting line  169  dependent from the crown block assembly  166  of the rig mast  164 . 
   To raise the tubing injector support system  80  using the lifting line  169 , the following steps replace the use of the hydraulic pressure to extend the lift cylinders  134 . A lifting line  169  controlled by the drilling rig drawworks  165  and dependent from the crown block assembly  166  of the drilling rig mast is attached to the spreader bar  170 . The spreader rods  171  at the ends of the spreader bar  170  are attached to the lifting eyes  100  of the injector cradle  81  of the injector support system  80  while the lift cylinders  84  are held in their retracted positions. 
   With the clamp assembly  90  gripping the tubing end  72 , the tubing injector support system  80  is then raised from the rear deck  21  of the trailer  20  by reeling on the lifting line  169  while the tubing reel is allowed to freewheel. When the swing arms  126  and  127  are vertical, then additional tension on the tubing  70  between the reel  40  and the injector  50  is provided by braking the reel. The resulting lateral force in the forward direction on the tubing injector support system  80  is controlled by the coiled tubing rig operator so that the intermediate frame  110  of the injector support system will not impact the rig floor  160 . The restraint on the motion of the tubing injector support system  80  provided by the damping of the swing cylinders  134  further aids the controlled lowering of the intermediate frame  110  to the rig floor  160 . This allows the coiled tubing injector  50  to be emplaced on the rig floor  160  so that coiled tubing operations can begin following disconnection of the spreader bar  170  with its spreader rods  171  and spreader bar clevis pins  172 . 
   To lower the tubing injector support system to the rear deck  21  of the trailer  20  for transport upon job completion, the following steps are used. The lifting line  169  with its spreader bar  170  and spreader rods  171  and spreader bar clevis pins  172  is reattached to the lifting eyes  100  of the injector cradle  81 . With the end  72  of the tubing string  70  rigidly held by the clamp assembly  90  of the injector cradle  81 , the storage reel  40  is rotated to initiate additional retrieval of the tubing  70 . This initially pulls the swing arms  126 ,  127  towards a vertical position. 
   As the swing arms  126 ,  127  approach vertical, the slack in the lifting line  169  is taken up so that the tubing injector support system  80  will not fall to the rear deck  21  of the trailer  20  after the swing arms pass their vertical position. The hydraulic damping action provided by the swing cylinders  134  further aids avoidance of the dropping of the injector support system  80  after the swing arms  126 ,  127  pass vertical during the lowering operation. The slowing of the lowering operation thus permits the tubing storage reel  40  to take up excess slack in the tubing  70  between the reel and the injector  50 . 
   ADVANTAGES OF THE INVENTION 
   The moveable tubing injector support assembly  80  is a self-contained means and apparatus for operating a coiled tubing rig either with its tubing injector located on the deck at the rear of its trailer in the conventional manner or operating the tubing injector on the rig floor of a drilling rig. 
   It is operationally much more convenient to have integral, rapidly operable means for both transferring and operating the coiled tubing injector either in its conventional position on the rear deck of the rig trailer or on the rig floor of a drilling rig. This saves operating time when the injector is to be transferred to and from a drilling rig floor and may avoid the need for providing a separate lifting means such as a crane or large forklift truck to effect the transfer. The transfer between the trailer and the drilling rig floor is easily accomplished with the self-contained lifting system shown in  FIG. 3 . 
   The second means of transferring the coiled tubing injector between the trailer and the rig floor of a drilling rig uses routinely available drilling rig equipment as a lifting means. Since the drilling rig lifting means is always available, this second lifting means is almost as easy to use as the hydraulic cylinders. Normally, hydraulic dampers do not need to be as large and expensive as the large hydraulic swing cylinders which would be needed to transfer the injector between the trailer and the drilling rig floor. 
   In addition, the lifting of the tubing injector support system between a first and second position provide can be used to induce additional tension in a coiled tubing string deployed into a well beyond that commonly available using only the coiled tubing injector. This novel feature is useful in the event that either the tubing has become stuck in the well or the tubing string is being used to unseat a packer or shift a downhole valve. These and other advantages of the present invention are readily recognizable by those skilled in the art. 
   Although the present invention and its advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims. For example, the configuration of various elements and/or the structure of the individual elements of the selectably elevatable coiled tubing injector can be varied without departing from the spirit of the invention.