WRENCHING TONG

Description

[0001] This invention relates to wrenching tongs and other power tongs.

[0002] In the construction of oil or gas wells it is usually necessary to construct long drill pipes. Due to the length of these pipes, sections or stands of pipe are progressively added to the pipe as it is lowered into the well from a drilling platform. In particular, when it is desired to add a section or stand of pipe the string is usually restrained from falling into the well by applying the slips of a spider located in the floor of the drilling platform. The new section or stand of pipe is then moved from a rack to the well centre above the spider. The threaded pin of the section or stand of pipe to be connected is then located over the threaded box of the pipe in the well and the connection is made up by rotation therebetween. An elevator is connected to the top of the new section or stand and the whole pipe string lifted slightly to enable the slips of the spider to be released. The whole pipe string is then lowered until the top of the section is adjacent the spider whereupon the slips of the spider are re-applied, the elevator disconnected and the process repeated.

[0003] It is common practice to use a power tong to torque the connection up to a predetermined torque in order to make this connection. The power tong is located on the platform, either on rails, or hung from a derrick on a chain. In order to make up or break out a threaded connection, a two tong arrangement is necessary. An active (or wrenching) tong supplies torque to the section of pipe above the threaded connection, while a passive (or back up) tong supplies a reaction torque below the threaded connection. The back up tong clamps the pipe below the threaded connection, and prevents it from rotating. This clamping can be performed mechanically, hydraulically or pneumatically. The wrenching tong clamps the upper part of the connection and is driven so that it supplies torque for a limited angle.

[0004] This power tong arrangement is also used to torque up connections between other tubulars, for example casing and tubing.

[0005] Normally, in order to supply high torque, the wrenching tong is driven hydraulically. One or two hydraulic cylinders drive the tong through a small angle, typically in the region of 25°, depending on the tong design. Due to the geometric configuration normally used, the torque output of the tong changes as a sine function of the angle driven, which results in a reduction of torque output across the drive angle of up to 15%.

[0006] In order to make up or break out a connection of modem drill pipe or casing, high torque must be supplied over a large angle. This angle is sometimes six times higher than a conventional wrenching tong can supply. In order to overcome this, the wrenching tong must grip and wrench the tubular several times to tighten or break the threaded connection fully. This has a number of disadvantages. The action of gripping and releasing the pipe repeatedly can damage the pipe surface. Due to the high costs associated with the construction of oil and gas wells, time is critical, and the repeated clamping and unclamping of the wrenching tong greatly increases the time taken to attach each new section or stand of tubulars. It also has the effect that the torque provided is discontinuous, increasing the difficulty of accurately controlling the torque with respect to the angle turned.

[0007] WO 93/18276 discloses an apparatus for applying torque to a first tubular relative to a second tubular. The apparatus comprises first and second tongs for gripping the first and second tubulars, respectively.

[0008] GB 2128526 discloses a tong for gripping a tubular, driven by a pinion and gear.

[0009] GB 1215967 discloses a tool secured in rotary table slips, and tongs for coupling and uncoupling tubulars.

[0010] According to a first aspect of the present invention there is provided a method of coupling a tool to a length of tubular, the method comprising the steps of:

securing the tool in a basket;

lowering a tong arrangement having a rotary part and a stationary part, relative to the basket to engage respective locking members of the tong arrangement and the basket, thereby fixing the basket and the tool relative to the stationary part of the tong arrangement; and

rotating the length of tubular using the rotary part of the tong arrangement so as to couple the tool to the length of tubular.

[0011] This method may be used to couple a tool such as a drill bit, to a length of drill pipe. The coupling portion of the length of drill pipe may be brought into proximity with a corresponding coupling portion of the tool either before or after the lowering of the tong arrangement.

[0012] The length of drill string may be gripped by the rotary part of the tong arrangement either before or after the lowering of the tong arrangement. The length of drill string may be located proximate to the basket containing the tool either before or after the string is gripped by the rotary part of the tong arrangement.

[0013] By carrying out the steps of the above fourth aspect of the present invention in reverse (including rotating the length of tubing in the opposite direction), a tool may be decoupled from a length of tubular.

[0014] According to a second aspect of the present invention there is provided apparatus for enabling a tool to be secured to a length of drill pipe, the apparatus comprising:

a basket arranged to securely retain the tool;

a tong arrangement having a rotary portion and a stationary portion, the rotary portion being arranged in use to grip and rotate the length of tubular; and

first locking means provided on the basket and second locking means provided on the stationary portion of the tong arrangement, the first and second locking means being engageable with one another to fix the basket relative to the stationary portion of the tong arrangement.

[0015] Preferably the first and second locking means are engageable and disengageble by means of linear movement of the tong arrangement relative to the basket.

[0016] Preferably, the basket is arranged to prevent rotation of the tool in the basket, wherein in use the rotary portion of the tong arrangement may be used to rotate the length of drill pipe to secure a screw connection between the length of drill pipe and the tool.

[0017] Preferably, one of the first and second locking means comprises one or more slots, and the other of the first and second locking means comprises one or more projecting members, the slots and the members being engageable and disengageable by relative linear movement of the tong arrangement and the basket.

[0018] Some preferred embodiments of the invention will now be described by way of example only and with reference to the accompanying drawings, in which:

Figure 1 is a view of an arrangement of a wrenching tong and a back-up tong suitable for use with the apparatus and method of the present invention;

Figure 2 is a side view of the wrenching tong and back-up tong of Figure 1;

Figure 3 is a view of the back-up tong of Figure 1;

Figure 4 is a cutaway view of the back-up tong of Figure 1;

Figure 5 is a cutaway view of the wrenching tong of Figure 1;

Figure 6 is a view of the wrenching tong and back-up tong of Figure 1 supported by a C-frame and fixed in a frame for handling equipment on tracks at a rig floor;

Figure 7 is a view of the wrenching tong and back-up tong of Figure 1 in use, with a tubular clamped in the wrenching tong;

Figure 8 is a view of an arrangement of an alternative wrenching tong and back-up tong suitable for use with the invention;

Figure 9 is a view of an arrangement of a further alternative wrenching tong and back-up tong suitable for use with the invention;

Figure 10 illustrates a modified tong arrangement suitable for use with the invention;

Figure 11 illustrates a modified back-up tong suitable for use with the invention;

Figure 12 illustrates in detail a clamping arrangement of the tong of Figure 11 including support elements;

Figure 13 illustrates an arrangement for connecting a drill bit to a length of drill pipe;

Figure 14 illustrates the arrangement of Figure 13 during the connection operation; and

Figure 15 illustrates the arrangement of Figure 13 following completion of the connection operation.

[0019] Figures 1 and 2 show an arrangement of a composite wrenching tong and back-up tong which is suitable for use with the present invention. A wrenching tong 1 is generally in the form of a disc with an opening 2 through the centre thereof for receiving a stand of drill pipe (not shown), and a recess 3 cut from the edge to the opening 2 at the centre. The wrenching tong 1 is provided with two pinion drives 4 arranged opposite each other at the periphery of the disc, equally spaced either side of the recess 3. Each pinion drive comprises a drive motor 5, drive shaft 6, and pinion 7 attached to the drive shaft 6.

[0020] A back-up tong 11 is located beneath the wrenching tong 1. The back-up tong is generally in the form of a disc with similar dimensions to the wrenching tong 1. The back-up tong is also provided with an opening 12 through the centre and a recess 13 from the edge to the opening at the centre. The opening 12 and recess 13 correspond to the opening 2 and recess 3 of the wrenching tong when the back-up tong 11 and the wrenching tong 1 are correctly aligned.

[0021] A plurality of guide rollers 10 or other guide elements are spaced around the edge of the wrenching tong 1 in order to maintain the alignment of the wrenching tong 1 with the back-up tong 11.

[0022] A gear 14 is provided around the periphery of the back-up tong 11, broken by the recess 13. The gear 14 meshes with the pinions 7 attached to the motors 5 on the wrenching tong, so that when the drive motors 5 drive the drive shafts 6 and gears 7, the wrenching tong 1 rotates relative to the back-up tong 11. The angle of rotation is limited by the recess 13 of the back up tong.

[0023] Figure 3 shows a back-up tong 11 before the wrenching tong is placed on top of it. The back-up tong 11 has a plurality of roller bearings 21, upon which the wrenching tong 1 is designed to be placed. The roller bearings 21 are supported by resilient means such as springs, elastic material or hydraulic/pneumatic cylinders, in order to support the wrenching tong during wrenching. During one wrenching cycle, the stands will move axially relative to one another as the connection is tightened. The wrenching tong must follow the axial movement of the top stand during one wrenching cycle. This axial travel length depends on the pitch of the thread.

[0024] Three clamping jaws 8 equipped with dies 9 are located inside each of the wrenching tong 1 and back-up tong 11. These are hydraulically driven for clamping the drill pipe stand in place in the centre of the wrenching tong. The hydraulic power supply may be provided by hoses (not shown).

[0025] Figure 4 shows the clamping mechanism of the back-up tong 11. Three hydraulic pistons 16, comprising piston rods 17 and chambers 18, are located inside the casing of the back-up tong 11. Each piston rod 17 has an end 19 which is secured to the outside edge of the back-up tong 11. At the other end of the piston, the jaw 8 containing two dies 9 with teeth (not shown) is fixed to the chamber 18 by a spherical bearing 20. With the arrangement shown, each drill pipe stand is clamped by three jaws and six dies at the joint. The spherical bearings 20 enable the jaws and dies to match the pipe surfaces closely, resulting in a low penetration depth of the teeth of the dies into the pipe surface, and thus prolonging the life of the drill pipe. The wrenching tong has a similar clamping jaw design, as shown in Figure 5.

[0026] Figure 6 shows the wrenching tong 1 and back-up tong 11 supported by a C-frame 22 for handling at the rig. The C-frame 22 is in turn fixed in a frame 23 for handling the equipment on tracks at the rig floor. A drill pipe spinner 24 is mounted on the C-frame above the tongs for rotating a drill pipe stand at high speed.

[0027] In order to make a connection between two stands of drill pipe, the recesses 3 and 13 in the wrenching 1 and back-up 11 tongs are aligned (the tongs may already be in this configuration following the removal of the tongs from a previous section of tubing). Two stands of drill pipe 25,26 are then introduced into the openings 2,12 in the wrenching and back-up tongs 1,11, respectively, through the recesses 3,13, and the lower stand 26 is clamped in position in the back-up tong 11. The upper stand 25 is introduced into the drill pipe spinner 24, and rotated at high speed in order to pretighten the threaded connection. The final high torque will be applied by the wrenching tong 1.

[0028] The upper stand 25 is now clamped in position in the opening 2 through the wrenching tong 1. The pinion drives 4 are then driven to torque the connection between the stands 25,26 until the connection is fully tightened or until one of the pinion drives 4 is at the edge of the recess 13, at which stage the wrenching tong 1 is at one end of its possible arc of travel relative to the back-up tong 11. The maximum wrenching angle which can be reached in one cycle in the embodiment shown is +/-75°. If necessary, the upper stand 25 can then be released from the wrenching tong 1, the tong returned to its original position, and the torquing process repeated.

[0029] To break a connection, the above operation is reversed.

[0030] An even larger wrenching angle can also be simply achieved with this arrangement, as shown in Figure 7. The stands of drill pipe 25,26 are introduced to the tongs 1,11 through the recesses 3,13 and pretightened using the drill pipe spinner 24 as described above. However, before the top stand 25 is clamped in place in the opening 2, the wrenching tong drive is reversed, and the wrenching tong 1 is driven to its end position relative to the back-up tong, as shown in Figure 7. The top stand 25 is now clamped with the tongs in this position, so that with the embodiment shown a wrenching angle of 150° is achievable.

[0031] Figure 8 shows an arrangement of a composite wrenching tong and back-up tong similar to that described above and again suitable for use with the method and apparatus of the present invention. However, in this case only one pinion drive 4 is used, which increases the possible wrenching angle to 300°.

[0032] Figure 9 shows another similar arrangement, with two pinion drives 4 being used as in Figures 1 to 7. This time the pinion drives 4 are not opposite each other, but spaced 120° each side of the recess 3. This gives the advantage of the torque and control provided by two drives, but allows a higher wrenching angle than the arrangement of Figure 1. The maximum wrenching angle in this embodiment will be in the region of 210°.

[0033] The torque can be monitored by measuring the reaction torque at each drive by means of a load cell, or by measuring the pressure of the drive motor.

[0034] It is to be understood that other variations may be used in connection with the invention. For example, the above examples show an arrangement whereby the pinion drives are mounted on the wrenching tong and the gear is mounted on the back-up tong. However, the arrangement could be the other way round with the pinion drives mounted to the back-up tong and the large gear mounted on the wrenching tong. Such an arrangement is illustrated in Figure 10.

[0035] Alternatively, the wrenching tong could be provided with a gear, and the pinion drives mounted on the frame 24.

[0036] Hydraulic clamping cylinders are shown, but the tong could clamp the drill pipe stands by any known means.

[0037] The above examples show one or two pinion drives, but more could be used if arranged in a suitable configuration.

[0038] Although the above examples have been described in relation to tightening stands of drill pipe, it is to be understood that the arrangements described are suitable for applying torque to any tubular sections.

[0039] Figure 11 illustrates in partial section a modified back-up tong 40 which may replace the back-up tong 11 of the example of Figure 1 to 9. The modified tong 40 has only two jaws 41 associated with respective clamping arrangements 42. Each arrangement 42 is held in place within the main body 43 of the tong 40 by a set of four "pendulum" bolts 44. A clamping arrangement 42 associated with four pendulum bolts 44 is illustrated in more detail in Figure 12 from which it can be seen that each bolt comprises a cylinder cut in half along its longitudinal axis to provide a flat surface and a rounded surface. The flat surface of each bolt 44 abuts the side of the clamping arrangement 42, whilst the rounded side is located in a rounded recess 45 provided in the side of the main body 43 opposed to the clamping arrangement. It will be appreciated that as the bolts 44 are able to rotate within their respective recesses in the tong body 43, each clamping arrangement 42 may pivot slightly about its centre. This allows the jaws 41 to conform to the outer surface of a tubular to be clamped when the tubular is for example not perfectly cylindrical.

[0040] Figure 13 illustrates apparatus in accordance with the invention which is used in association with a tong arrangement 49 to connect and disconnect a tool such as a drill bit to and from a length of tubular such as a drill pipe. The apparatus comprises a basket 50 which is arranged in use to be placed on the floor of a drilling rig. The basket 50 has an opening in the top thereof for receiving a tool 51 which is to be connected to a length of tubular 52. The opening has a shape which is complimentary to the shape of the tool 51 such that the tool is held securely in an upright position and rotation of the tool within the basket 50 is prevented.

[0041] Two opposed sides of an upper plate of the basket 50 are provided with slots 53. These slots 53 are shaped to receive locking members 54 which project downwardly from the lower surface of the back-up tong 55 of the tong arrangement. The operation to connect a tool will now be described.

[0042] As shown in Figure 13, the tool 51 is first located in the basket 50. The length of tubular 52 is moved to a position over the tool (Figure 14) and is lowered to bring the box of the tubular into engagement with the externally threaded coupling of the tool 51. At this point, the tong arrangement is brought up to the tubular 52 with the jaws of the rotary and back-up tongs being fully opened, and the tong is placed around the tubular 52. The tong arrangement is then lowered within its frame, to a position in which the locking members 54 are received by the respective receiving slots 53 of the basket 50. In this position, the basket is locked to the back-up tong. The jaws of the rotary tong are then clamped against the tubular 52 and the rotary tong rotated, relative to the back-up tong, to tighten the threaded joint (Figure 15). The jaws of the rotary tong are then released, and the tong arrangement withdrawn from around the tubular. The tubular and the connected tool can then be lifted clear of the basket 50.

[0043] It will be appreciated that the tool 51 may be disconnected from the tubular 52 by carrying out the same operation but in reverse.

Claims

1. A method of coupling a tool to a length of tubular, the method comprising the steps of:

securing the tool in a basket;

lowering a tong arrangement having a rotary part and a stationary part, relative to the basket to engage respective locking members of the tong arrangement and the basket, thereby fixing the basket and the tool relative to the stationary part of the tong arrangement; and

rotating the length of tubular using the rotary part of the tong arrangement so as to couple the tool to the length of tubular.

2. Apparatus for enabling a tool to be secured to a length of drill pipe, the apparatus comprising:

a basket arranged to securely retain the tool; and

a tong arrangement having a rotary portion and a stationary portion, the rotary portion being arranged in use to grip and rotate the length of tubular;

   characterised by first locking means provided on the basket and second locking means provided on the stationary portion of the tong arrangement, the first and second locking means being engageable with one another to fix the basket relative to the stationary portion of the tong arrangement.

3. Apparatus according to claim 2, wherein the first and second locking means are engageable and disengageble by means of linear movement of the tong arrangement relative to the basket.

4. Apparatus according to claim 2 or 3, wherein the basket is arranged to prevent rotation of the tool in the basket so that in use the rotary portion of the tong arrangement can be used to rotate the length of drill pipe to secure a screw connection between the length of drill pipe and the tool.

5. Apparatus according to any one of claims 2 to 4, wherein one of the first and second locking means comprises one or more slots, and the other of the first and second locking means comprises one or more projecting members, the slots and the members being engageable and disengageable by relative linear movement of the tong arrangement and the basket.

Ansprüche

1. Verfahren zum Koppeln eines Werkzeugs an eine Rohrabschnittslänge, wobei das Verfahren die folgenden Schritte umfaßt:

Befestigen des Werkzeugs in einem Korb,

Absenken einer Zangenanordnung mit einem rotierenden Teil und einem feststehenden Teil, im Verhältnis zu dem Korb, um entsprechende Verriegelungselemente der Zangenanordnung und des Korbs in Eingriff zu bringen, wodurch der Korb und das Werkzeug im Verhältnis zum feststehenden Teil der Zangenanordnung fixiert werden, und

Drehen der Rohrabschnittslänge unter Verwendung des rotierenden Teils der Zangenanordnung, um so das Werkzeug an die Rohrabschnittslänge zu koppeln.

2. Vorrichtung, um zu ermöglichen, daß ein Werkzeug an einer Bohrrohrlänge befestigt wird, wobei die Vorrichtung folgendes umfaßt:

einen Korb, angeordnet zum sicheren Halten des Werkzeugs, und

eine Zangenanordnung mit einem rotierenden Teil und einem feststehenden Teil, wobei der rotierende Teil bei Anwendung angeordnet wird, um die Rohrabschnittslänge zu ergreifen und zu drehen,

gekennzeichnet durch erste, am Korb bereitgestellte, Verriegelungsmittel und zweite, am feststehenden Teil der Zangenanordnung bereitgestellte, Verriegelungsmittel, wobei die ersten und die zweiten Verriegelungsmittel miteinander in Eingriff gebracht werden können, um den Korb im Verhältnis zum feststehenden Teil der Zangenanordnung zu fixieren.

3. Vorrichtung nach Anspruch 2, bei der die ersten und die zweiten Verriegelungsmittel mit Hilfe einer linearen Bewegung der Zangenanordnung im Verhältnis zum Korb eingerückt und ausgerückt werden können.

4. Vorrichtung nach Anspruch 2 oder 3, bei welcher der Korb angeordnet wird, um ein Drehen des Werkzeugs im Korb zu verhindern, so daß bei Anwendung der rotierende Teil der Zangenanordnung verwendet werden kann, um die Bohrrohrlänge zu drehen, um eine Schraubverbindung zwischen der Bohrrohrlänge und dem Werkzeug zu sichern.

5. Vorrichtung nach einem der Ansprüche 2 bis 4, bei der das eine der ersten und zweiten Verriegelungsmittel einen oder mehrere Schlitze umfaßt und das andere der ersten und zweiten Verriegelungsmittel ein oder mehrere vorstehende Elemente umfaßt, wobei die Schlitze und die Elemente durch eine relative lineare Bewegung der Zangenanordnung und des Korbs eingerückt und ausgerückt werden können.

Revendications

1. Procédé d'accouplement d'un outil à une longueur de tube, le procédé comprenant les étapes ci-dessous:

fixation de l'outil dans un panier;

abaissement d'un dispositif de clé à tiges comportant une partie rotative et une partie stationnaire par rapport au panier pour engager des éléments de verrouillage respectifs du dispositif de clé à tiges et du panier, afin de fixer ainsi le panier et l'outil par rapport à la partie stationnaire du dispositif de clé à tiges; et

rotation de la longueur de tube par l'intermédiaire de la partie rotative du dispositif de clé à tiges, pour accoupler ainsi l'outil à la longueur de tube.

2. Dispositif permettant la fixation d'un outil à une longueur de tube de forage, le dispositif comprenant:

un panier destiné à retenir fermement l'outil; et

un dispositif de clé à tiges comportant une partie rotative et une partie stationnaire, la partie rotative servant en service à saisir et à faire tourner la longueur de tube;

   caractérisé par un premier moyen de verrouillage agencé sur le panier et un deuxième moyen de verrouillage agencé sur la partie stationnaire du dispositif de clé à tiges, les premier et deuxième moyens de verrouillage pouvant s'engager mutuellement pour fixer le panier par rapport à la partie stationnaire du dispositif de clé à tiges.

3. Dispositif selon la revendication 2, dans lequel les premier et deuxième moyens de verrouillage peuvent s'engager et se dégager par l'intermédiaire d'un déplacement linéaire du dispositif de clé à tiges par rapport au panier.

4. Dispositif selon les revendications 2 ou 3, dans lequel le panier est destiné à empêcher la rotation de l'outil dans le panier, de sorte qu'en service, la partie rotative du dispositif de clé à tiges peut servir à faire tourner la longueur du tube de forage pour assurer une connexion par vis entre la longueur du tube de forage et l'outil.

5. Dispositif selon l'une quelconque des revendications 2 à 4, dans lequel l'un des premier et deuxième moyens de verrouillage comprend une ou plusieurs fentes, l'autre des premier et deuxième moyens de verrouillage comprenant un ou plusieurs éléments en saillie, les fentes et les éléments pouvant s'engager et se dégager par l'intermédiaire d'un déplacement linéaire relatif du dispositif de clé à tiges et du panier.

Drawing