DUAL STRING BACKUP TONG

Abstract: A backup tong (1) having an inner throat (19) sized to accommodate a second pipe string while a first pipe string is held within the jaws (12, 13) of the tong is disclosed. The inventive backup tong facilitates operations on dual pipe strings by allowing the tong to grip not only the closer of two pipe strings, but also the farther of the pipe strings by allowing the nearer pipe string to reside in an inner throat of the backup tong, between the gripping members (16, 17) of the tong and the body of the backup tong, while the farther pipe string is held between the gripping members. The inventive backup tong thereby allows the operator to grip either of the pipe strings from a single side, eliminating the side-to-side movement (and corresponding time and risk of harm) which is required when using prior art backup tongs.

Description: DUAL STRING BACKUP TONG FIELD OF THE INVENTION: The present invention relates generally to tools used in oilfield operations and more particularly to a backup tong suitable for use in dual tubing strings operations in conjunction with a power tong to make up or break apart joints of pipe strings. BACKGROUND OF THE INVENTION: Tongs have long been used in oilfield operations to grip and rotate pipe segments and thereby "make up" or "break apart" joints in a pipe string. A backup tong is used to grip and prevent rotation of the lower pipe in the joint while the upper pipe segment is gripped and rotated by a second tong. Typically, this second tong is not manually used to rotate the upper pipe, but is instead power-driven. Backup tongs are thus used only in conjunc- tion with a second tong, whether the second tong be manually operated or actually "powered." Tongs are generally designed to operate only on a single string of pipe. In other words, they are designed to grip and/or rotate a single pipe without regard to whether there may be any other pipes nearby, much less within the same wellbore. In a situation in which there are two pipe strings in the same casing, the tongs may be used if the strings are sufficiently far apart to allow access to each string or the two strings may be "splayed" apart to make room to engage the tongs. Even if the tongs can be used with dual tubing strings (with or without splaying the pipe strings) , the tongs must be used on the first (the nearest) of the two pipe strings, then backed off, moved to the opposite side of the pipe strings and then moved onto the second pipe string, which after moving the tongs becomes the nearer of the two. The movement of the tongs back and forth from one side of the tubing strings to the other takes a great deal of time and creates a much greater risk of harm to the tong operator than when the tongs are simply moved forward or backward onto or off of a single pipe string. The use of prior art tongs (which are designed for use in single string operations) is therefore troublesome and time consuming in situations where there are two or even three pipe strings. Although this disclosure relates to backup tongs, the scope of the problem is also apparent from the shortcomings of prior art power tongs. U.S. Patent No. 4,590,823 to Neves, et al. shows an open-throat power tong which allows one pipe string to be gripped while the adjacent string is positioned within the outer throat of the tong (i.e., the opening between the gripping mechanism of the tong and the exterior of the tong). While Neves, et al. discloses a type of power tong which can be used with dual pipe strings, it does not disclose any way to overcome the problem of having to move the power tong, or a backup tong used therewith, from side to side to properly position the first and second pipe strings between the jaws of the tong and in the throat of the tong, respectively. Backup tongs, like power tongs, are typically designed for use in single string operations. As noted above, some designs of backup tongs may be used in dual string operations by utilizing an open throat design which can accommodate a second pipe in the outer throat of the tong while gripping a first pipe string between its jaws. While this method of using a backup tong is known in the art, it requires that the backup tong be used on a first string, then backed off of the first string, moved approximately 180 degrees to face the second pipe string and then moved forward to engage the second pipe string. Although this procedure makes dual string operations possible with backup tongs designed to operate on a single string, the extra movement is time consuming and ineffi- cient and poses a much greater risk of injury than a tong which does not have to be repeatedly swung around the pipe strings. SUMMARY OF THE INVENTION: The shortcomings of the devices in the prior art are overcome in the present invention by providing a backup tong which does not need to be backed off of a first pipe string, swung around to the opposite side of the string and engaged with a second pipe string from the opposite direction. This is accomplished by placing the gripping members of the backup tongs at the end of a set of extended jaw members which have an inner throat between the gripping members and the main body of the backup tong. This inner throat is directly adjacent to the pipe which is gripped by the jaws of the backup tong and is on the side of the pipe opposite the outer throat, through which the pipe passes as the tong is moved onto the pipe. This allows the invention to grip the further of two strings while the nearer string is within the inner throat of the backup tong, then release the far string, move back and grip the near string. Likewise, in backout mode, the inventive tong can grip the nearer of two pipe strings as a conventional backup tong would, then simply release the first string and move forward to grip the second string while the first string is disposed in the inner throat of the backup tong. The inner throat of the tong can also be designed to accommodate three pipe strings, although three- string operations (one string in the jaws of the tong and two strings in the inner throat) are rarely conducted. Obviously, the invention has utility in single-string operations as well. The ability to conduct dual string operations with minimal movement of the backup tong greatly reduces the time required to make or break the joints of dual pipe strings. This in turn provides increased efficiency, reduced costs and greater safety for persons operating the tongs. It is therefore an object of the invention to provide a backup tong which can accommodate a second pipe on either side of a first pipe which is held between the jaws of the backup tong and thereby allows the tong to grip either pipe with only a small lateral movement. It is another object of the invention to provide a backup tong which reduces the time, effort and related expense to make up and break apart pipe joints in multiple-string operations. It is another object of the invention to provide a backup tong which reduces the risk of harm to the tong operator by minimizing the movement of the backup tong during its use in multiple-string operations. BRIEF DESCRIPTION OF THE DRAWINGS: Figure 1 is a perspective view of one embodiment of the inventive backup tong in use, with a pipe disposed in the inner throat of the tong. Figure 2 is a perspective view of one embodiment of the inventive backup tong in use, with no pipe disposed in the inner throat of the tong. Figure 3 is a top view of one embodiment of the inventive backup tong with a pipe disposed in the inner throat of the tong. Figure 4 is a top view of one embodiment of the inventive backup tong with no pipe disposed in the inner throat of the tong. Figure 5 is a top view of the preferred embodiment of the inventive backup tong with a pipe disposed in the inner throat of the tong. Figure 6 is a perspective view of an alternate embodiment of the inventive backup tong which does not have an inner throat. Figure 7 is a perspective view of an alternate embodiment of the inventive backup tong which does not have an inner throat. Figure 8 is a perspective view of an alternate embodiment of the inventive backup tong which does not have an inner throat. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT: Referring to Figure 1, one embodiment of the backup tong of the present invention is shown. The body of the backup tong has an upper plate 10 and a lower plate 11. Between these plates are two jaw members 12, 13 which pivot about bolts 14, 15. At the outer ends of the jaw members 12, 13 are gripping members 16, 17. Gripping members 16, 17 carry dies 21, 22 which actually come into contact with and grip a pipe which is situated between them. A hydraulic actuator 18 (not shown) is disposed between the jaw members and connected to these members at their inner ends (the ends opposite gripping members 16, 17) . As the hydraulic actuator 18 forces the non-gripping ends of the jaw members outward, the jaw members pivot around bolts 14, 15 and force gripping members 16, 17 inward. Likewise, when actuator 18 pulls jaw members 12, 13 inward, the pivoting of the jaw members forces gripping members 16, 17 outward. Although this embodiment utilizes the two pivoting jaw members, this is considered a design choice and may be replaced in the invention by a wide variety of jaw designs which are known in the art. These jaw designs may incorporate pivoting jaw members, stationary jaw members with laterally movable gripping members, or any other arrangement of jaw members and/or gripping members which allows the incorporation of an inner throat into the tong design. In fact, in the preferred embodiment, shown in Figure 5, utilizes two jaw members 62, 63 which are connected to each other at pivot pin 80 instead of being connected to a separate tong body. Just as in the previously described embodiment, the preferred embodiment has gripping members 66, 67 which are pivotally attached to jaw members 62, 63. Jaw members 62, 63 have extensions 94, 96 which provide a location for the mounting of hydraulic actuator 68. The piston 84 and cylinder 82 of the actuator are pivotally connected to jaw members 62, 63 via attachment arms 86, 88. When the piston moves toward the closed end of the cylinder, contracting the length of the actuator, the gripping members are moved apart, releasing the pipe. When the piston is forced away from the closed end of the cylinder, extending the length of the actuator, the gripping members are forced toward each other, thereby gripping the pipe. The backup tong assembly shown in Figure 4, and particularly upper plate 10 and lower plate 11, is formed with an inner throat or recess 19 immediately behind gripping members 16, 17 (i.e. between gripping members 16, 17 and plates 10, 11). Because recess 19 is disposed between pivot bolts 14 and 15, jaw members 12, 13 essentially pivot around the recess so that a pipe string disposed within the recess is not disturbed by operation of the backup tong. As mentioned above, however, this pivoting jaw arrangement is not required and recess 19 is also incorporated into the preferred embodiment shown in Figure 5. In fact, recess 19 need not even be characterized as a recess within the mechanical components of the backup tong. Figures 6-8 show embodiments of the inventive backup tong which grip the pipe from above so that additional pipes may be disposed adjacent to a first pipe which is being gripped by the tong. Each of these embodiments has a backup tong which, instead of being connected to a torque post which is in turn connected to a power tong, is directly connected to and integral with the power tong. Figure 6 shows a pair of jaw members 102, 103 which are attached at their upper ends to power tong body 110 by pivoting connections 104, 105 (105 not shown). At the lower ends of jaw members 102, 103 are gripping members 108, 109. Although not shown in the detail of Figure 6, gripping members 108, 109 hold dies which actually contact the pipe and grip it therebetween. Hydraulic actuators 106, 107 (107 not shown) are pivotally attached to the jaw members at a point between the upper (104, 105) and lower (112, 113) pivot connections. Actuators 106, 107 are attached at their opposite ends to structural members so that jaw members 102, 103 will be forced toward each other when the actuators are extended. Figure 7 shows a pair of jaw members 120, 121 which are attached at their upper ends to power tong body 110 by pivoting connections 122, 123 (123 not shown). At the lower ends of jaw members 102, 103 are gripping members 124, 125. Gripping members 124, 125 hold dies which contact and grip the pipe. The embodiment shown in Figure 7 does not use hydraulic actuators to urge jaw members 120, 121 together, but instead utilizes interlocking faces on gripping members 124, 125. Gripping members 124, 125 slide along jaw members 120, 121 so that the gripping members are vertically moveable with respect to each other. The gripping members are placed on opposite sides of a pipe, their interlocking faces are placed in contact with each other and the gripping members and slid together to interlock and grip the pipe therebetween. Figure 7 shows that the faces of gripping members 124, 125 use an interlocking dovetail arrangement to hold the gripping members together. Figure 8 shows another alternate embodiment of the invention which has a pair of jaw members 120, 121 pivotally attached to the power tong body. This embodiment uses a pair of interlocking gripping members similar to the arrangement of Figure 7, but the gripping members 134, 135 are attached to jaw members 120, 121 by pivot points 136, 137. The embodiment of Figure 8 includes a pair of actuators 142, 143 which are attached to gripping members 134, 135 at pivot points 138, 139 and which urge the gripping members to swing upward into locking engagement or downward to release a pipe held therebetween. The preferred embodiment of the invention is used in conjunc- tion with a power tong. In Figures 1 and 2, the invention is shown mounted to a torque post 30. The invention is mounted on the torque post by means of two pivoting arms 28, 29 which allow the invention to shift laterally with respect to a line extending from the center of recess 19 to a point midway between gripping members 16, 17. Also mounted on torque post 30 is a power tong 2 which is preferably capable of dual-string operations. The mounting of the backup tong 1 and the power tong 2 on the torque post prevents them from rotating with respect to each other. Gripping members 16, 17 are pivotally connected to jaw members 12, 13. Pivot connections 32, 33 allow gripping members 16, 17 to have a small range of motion in the direction essentially perpen¬ dicular to the motion imparted to the gripping members through movement of jaw members 12, 13. The degree of freedom provided by pivot connections 32, 33 allows gripping members 16, 17 to accommodate a pipe therebetween and adjust their positions so that the faces 23, 24 of dies 21, 22 come fully into contact with the pipe. In the preferred embodiment, the power tong 2 which is used with the inventive backup tong 1 is also capable of dual-string operations. Figure 1 shows a closed-throat power tong which comprises a multi-sectioned gripping assembly 40 mounted on power tong body 41. Also mounted on power tong body 41 is drive motor 44. Contained within power tong body 41 is the drive mechanism (not shown) which transfers power from the drive motor 44 to the gripping assembly 40, causing the gripping assembly to rotate. The operation of the drive mechanism and the rotation of the gripping assembly are regulated by controls 45. The physical positioning of the backup tong and power tong are facilitated by structural arms 37, 38 which are rigidly connected to torque post 30 structural arms 37, 38 have handles 35, 36 which allow the tong operator to grasp and position the backup and power tongs. The power tong body 41 is mounted to power tong frame 42. Power tong frame 42 is in turn connected to the upper portion of torque post 30. As mentioned above, the attachment of both power tong 2 and the inventive backup tong l to torque post 30 prevents the tongs from rotating relative to each other. The torque between these two components is therefore transferred to the pipe and coupling which are held by the power tong and backup tong, respectively. Referring to Figures 1 and 3, it can be seen that the present invention can operate on dual pipe strings without having to move the backup tongs from one side of the dual pipe strings to the other, as is the case with prior art backup tongs. Both the invention, and conventional single-string backup tongs can be positioned to grip the closer of a pair of adjacent pipe strings in the same way (see Figures 2 and 4) . In order for a conventional backup tong to grasp the second (the farther) of the pipe strings, the tong must be backed off the near string, moved to the opposite side of the pair of pipe strings so that the second string is the nearer of the two, and moved forward to engage the pipe string. In other words, the conventional tong can only engage the nearer of the two pipes, so it must be repositioned on the opposite side of the dual strings before it can engage the second pipe. The invention, on the other hand, simply releases the first string, moves forward several inches so that the first pipe string is within the throat of the tong, and grips the second pipe string. The inventive tong can, of course, also initially grip the second pipe string while the first pipe string is within the inner throat of the tong, then release the second string, move backward and grip the first string. No time or effort is wasted in having to move the backup tong from one side of the pair of pipe strings to the other — the tong is simply shifted forward or backward several inches. (It does not matter which of the two pipes is gripped first or second by the tong.) The foregoing describes the use of the invention with two pipe strings. The invention nevertheless has application to operations which utilize more than two pipe strings, although these operations are somewhat rare. In such cases, the throat of the invention need only be enlarged to accommodate the additional pipe strings. While the preferred embodiment utilizes a body (formed by upper and lower plates 10, 11) with two movable jaw members, the arrangement of the body, jaw members and other components is not essential to the invention. The practice of the invention requires the use of a gripping mechanism in conjunction with recesses or spaces which allow a second pipe to reside adjacent to a first pipe on either of two substantially opposite sides of a first pipe held by the gripping mechanism. The gripping mechanism may use more or less than two movable members, it may use hydraulic, mechanical or other types of actuators, it may use pivoting or non-pivoting members, and so on. Many such modifications to the design of the invention will be obvious to a person of ordinary skill in the art and, although these alternate embodiments of the invention are not expressly described herein, they are contemplated by the invention and are within the scope of this disclosure. Many modifications can be made to the preferred embodiment and numerous resulting alternate embodiments of the invention can be designed without departing from the scope of the invention. The specific embodiments disclosed herein are exemplary and other embodiments will be obvious from this disclosure to those skilled in the art.

Claims: CLAIMS; What is claimed is: 1. A backup tong for gripping a first pipe in multiple- tubing operations comprising a gripping mechanism for engaging the first pipe and preventing movement of the first pipe with respect to the gripping mechanism, the gripping mechanism being shaped to provide a first space closely adjacent to the first pipe to accommodate a second pipe there within, the gripping mechanism being shaped to further provide a second space opposite the first space, the second space being closely adjacent to the first pipe and sized to accommodate the second pipe there within. 2. The backup tong of claim 1 wherein the gripping mechanism comprises a plurality of jaw members which are movable from a first position in which the jaw members are spaced to allow the first pipe to move freely therebetween to a second position in which the first pipe is engaged and held therebetween. 3. The backup tong of claim 2 wherein the gripping mechanism further comprises an actuator which is connected to the jaw members and which controls the movement of the jaw members and moves the jaw members between the jaw members' first position and second position. 4. The backup tong of claim 3 wherein the jaw members are opposed so that they engage substantially opposite sides of the first pipe. 5. The backup tong of claim 3 wherein the gripping mechanism further comprises a central member, each of two jaw members being elongated and having a gripping end and a second end, each jaw member being pivotally connected at a point intermediate the gripping and second ends to opposite sides of the central member, the actuator being disposed between the second ends of the jaw members so that the jaw members are engaged with the first pipe by forcing the second ends of the jaw members away from each other. 6. The backup tong of claim 5 wherein each jaw member further comprises a die disposed at the gripping end of each jaw member so that the first pipe is engaged by the dies when the jaw members are in the second position. 7. The backup tong of claim 6 wherein each jaw member further comprises a gripping member, the gripping member having a pivot end and an engagement end, the pivot end being pivotally attached to the gripping end of the jaw member, the engagement end being disposed toward the first space. 8. The backup tong of claim 1 wherein the gripping mechanism comprises a plurality of vertical members, each vertical member having an upper end and a lower end, the upper ends being connected to a power tong and the lower ends being connected to a plurality of gripping members, each gripping member having a gripping surface for engaging a gripping a pipe disposed between the gripping members. 9. The backup tong of claim 9 further comprising a one or more actuators connected to the vertical members for urging the vertical members in a direction radial to the pipe disposed therebetween and the gripping members attached to the vertical members are alternately engaged and disengaged with the pipe. 10. The backup tong of claim 8 wherein each gripping member has an interlocking surface which is shaped to contact and interlock with the interlocking surface of another gripping member, the gripping members having a first position in which the gripping members are interlocked and thereby held in engagement with the pipe disposed therebetween and a second position in which the pipe disposed therebetween is free to move between the gripping members. 11. The backup tong of claim 10 wherein the gripping members are slidably connected to the vertical members. 12. The backup tong of claim 10 further comprising a plurality of actuators, each actuator having a first end and a second end, the first end of each actuator being connected to one of the vertical members and the second end of each actuator being connected to one of the gripping members, the gripping members being pivotally connected to one of the vertical members so that the actuators cause the gripping members to pivot between their first and second positions. 13. A backup tong for gripping a first pipe in multiple- tubing operations while allowing a second pipe to reside in close proximity thereto without necessitating splaying of the first and second pipes, comprising: a body; and two jaws which connected to the body and which are movable with respect to each other, the jaws extending outward from the body in generally the same direction so that a space is defined on three sides by the body and jaws and on the fourth side by the first pipe when engaged by the backup tong, the space being sized to accommodate a second pipe therein, the jaws having an open position in which the first pipe may be moved therebetween and a closed position in which the first pipe is held therebetween. 14. The backup tong of claim 13 wherein each jaw has a gripping end, and wherein the backup tong further comprises a gripping member pivotally attached to the gripping end of each jaw, the gripping members being disposed to engage the first pipe. 15. The backup tong of claim 13 wherein the gripping members further comprise a pair of dies, each die being disposed so as to engage the first pipe when the jaws are in the closed position. 16. The backup tong of claim 13, further comprising an actuator which is connected to the jaws and which moves the jaws between the open position and the closed position. 17. A method for using a backup tong to grip adjacent pipe strings in a multiple-tubing subterranean wellbore operations without having to substantially change the position of the backup tong, comprising: providing a backup tong having a pair of jaws, each of which has a gripping end, the jaws being movable with respect to each other and having an inner throat therebetween, the inner throat being sized to accommodate a first pipe therein while a second pipe is held between the gripping ends of the jaws; positioning the backup tong so that a first pipe string is between the gripping ends of the jaws and a second pipe string is disposed within the inner throat of the backup tong; moving the jaws of the backup tong to engage the gripping ends with the first pipe string. 18. The method of claim 17, further comprising the steps of: moving the jaws out of engagement with the first pipe string; moving the backup tong while maintaining the orientation of the backup tong in a direction from the first pipe string toward the second pipe string until the second pipe string is between the gripping ends of the jaws of the backup tong while maintaining the orientation of the backup tong; moving the jaws of the backup tong to engage the gripping ends with the second pipe string. 19. An improvement in a backup tong assembly for preventing rotation of a first pipe section in threaded engagement with a second pipe section which is being rotated, the backup tong having a body and a plurality of gripping members connected thereto for engaging the first pipe section in a first opening between the gripping members, the improvement comprising: a second opening disposed between the body and the first opening, the second opening shaped to accommodate at least one pipe there within. 20. The improvement of claim 19, further comprising: a third opening disposed adjacent the first opening opposite the second opening, the third opening being shaped to accommodate at least one pipe there within.

Inventors: BOULIGNY VERNON, VEVERICA MARK, BOULIGNY, VERNON, VEVERICA, MARK
Applicants: FRANK S CASING AND RENTAL TOOL, FRANK'S CASING AND RENTAL TOOLS, INC.
Application year: 1997
Main classification: B25B13
IPC codes: E21B19