Duplex snubbing jack

Abstract

A duplex snubbing jack and method of snubbing pipe into a well bore which includes first and second gripping units that alternately and synchronously grip and release a length of pipe to be attached to a pipe string. The first and second gripping units are synchronously movable upward and downward toward and away from each other to push or pull the pipe through a BOP stack and into or out of a wellbore. Linear actuators are used to synchronously move the first and second gripping units. Guide rails are provided to laterally support the pipe as the pipe is pushed or pulled through the BOP stack into or out of the wellbore. The first and second gripping units are preferably slip-type spiders.

Claims

1. A snubbing jack comprising: (a) a base, said base mountable above a BOP stack that is in axial alignment with a wellbore, said base having a central opening in axial alignment with said BOP stack and said wellbore; (b) a cap positioned above said base, said cap having a central opening in axial alignment with said central opening of said base; (c) guide rails extending between said base and said cap, said guide rails positioned around said central opening of said base and said central opening of said cap whereby a pipe positioned axially through said central opening of said base and said central opening of said cap is laterally supported by said guide rails; (d) a first pipe gripping unit, said first pipe gripping unit having a central opening in axial alignment with said central opening of said base and said central opening of said cap, said first pipe gripping unit slidably positionable along said guide rails toward and away from said base, said first pipe gripping unit having a pipe gripping mechanism whereby a pipe may be selectively gripped or released; (e) a second pipe gripping unit positioned below first pipe gripping unit, said second pipe gripping unit having a central opening in axial alignment with said central opening of said first pipe gripping unit, said second gripping unit having a pipe gripping mechanism whereby a pipe may be selectively gripped or released; and (f) a first linear actuator attached to said base and said first pipe gripping unit whereby said first pipe gripping unit may be moved linearly downward and upward along said guide rails toward and away from said second pipe gripping unit.

2. The snubbing jack as recited in claim 1, wherein said first linear actuator includes a rack and pinion mechanism whereby a jack rod is extended.

3. The snubbing jack as recited in claim 2, further comprising a second linear actuator attached to said base and said second pipe gripping unit whereby said second pipe gripping unit may be moved linearly upward and downward along said guide rails toward and away from said second pipe gripping unit.

4. The snubbing jack as recited in claim 3, wherein said first pipe gripping unit and said second pipe gripping unit has a slip pipe gripping mechanism.

5. The snubbing jack as recited in claim 4, wherein said first and second gripping units include a plurality of slidably positionable slips pivotally attached to a timing ring wherein said slidably positionable slips move radially inward and outward in response to retraction and extension of a piston rod attached to said timing ring.

6. The snubbing jack as recited in claim 1, wherein said first linear actuator is a hydraulic cylinder with an extendable and retractable piston rod.

7. The snubbing jack as recited in claim 6, further comprising a second linear actuator attached to said base and said second pipe gripping unit whereby said second pipe gripping unit may be moved linearly upward and downward along said guide rails toward and away from said first pipe gripping unit.

8. The snubbing jack as recited in claim 7, wherein said first pipe gripping unit and said second pipe gripping unit has a slip pipe gripping mechanism.

9. The snubbing jack as recited in claim 8, wherein said first and second gripping units include a plurality of slidably positionable slips pivotally attached to a timing ring wherein said slidably positionable slips move radially inward and outward in response to retraction and extension of a piston rod attached to said timing ring.

10. A snubbing jack comprising: (a) a base, said based mounted above a BOP stack that is in axial alignment with a wellbore, said base having a central opening in axial alignment with said BOP stack and said wellbore; (b) a cap positioned above said base, said cap having a central opening in axial alignment with said central opening of said base; (c) guide rails extending between said base and said cap, said guide rails positioned around said central opening of said base and said central opening of said cap; (d) a first pipe gripping unit, said first pipe gripping unit having a central opening in axial alignment with said central opening of said base and said central opening of said cap, said first pipe gripping unit slidably positionable along said guide rails toward and away from said base, said first pipe gripping unit having a pipe gripping mechanism whereby a pipe may be selectively gripped or released; (e) a second pipe gripping unit positioned below first pipe gripping unit, said second pipe gripping unit having a central opening in axial alignment with said central opening of said first pipe gripping unit, said second gripping unit having a pipe gripping mechanism whereby a pipe may be selectively gripped or released; (f) a first linear actuator attached to said base and said first pipe gripping unit whereby said first pipe gripping unit may be moved linearly downward and upward along said guide rails toward and away from said second pipe gripping unit; and (g) a second linear actuator attached to said base and said second pipe gripping unit whereby said second pipe gripping unit may be moved linearly upward and downward along said guide rails toward and away from said first pipe gripping unit.

11. The snubbing jack as recited in claim 10, wherein a pipe extending axially through said central opening of said first pipe gripping unit and said central opening of said second pipe gripping unit is laterally supported by said guide rails.

12. The snubbing jack as recited in claim 11, wherein said first and said second pipe gripping units each include a plurality of slidably positionable gripping slips pivotally attached to a timing ring wherein said slidably positionable gripping slips move radially inward and outward in response to retraction and extension of a piston rod attached to said timing ring.

13. The snubbing jack as recited in claim 12, wherein said first linear actuator and said second linear actuator includes a rack and pinon mechanism whereby a jack rod is extended.

14. The snubbing jack as recited in claim 12, wherein said first linear actuator and said second linear actuator is a hydraulic cylinder with an extendable and retractable piston rod.

15. A method of snubbing a length of pipe into a wellbore through a BOP stack comprising the steps of: (a) providing a snubbing unit having a central opening, said snubbing unit having a first pipe gripping unit, said first pipe gripping unit having central opening in axial alignment with said central opening of said snubbing unit and a pipe gripping mechanism whereby a pipe may be selectively gripped or released by opening and closing said pipe gripping mechanism, a second pipe gripping unit positioned below first pipe gripping unit, said second gripping unit having central opening in axial alignment with said central opening of said snubbing unit and a pipe gripping mechanism whereby a pipe may be selectively gripped or released by opening and closing said pipe gripping mechanism, and guide rails positioned around said central opening of said first pipe gripping unit and said central opening of said second pipe gripping whereby said first pipe gripping unit and said second pipe gripping unit may be slidably positioned upward and downward along said guide rails; (b) mounting said snubbing unit above a BOP stack positioned in axial alignment with a pipe string positioned in a wellbore wherein said central opening of said snubbing unit and said central openings of said first and said second pipe gripping units are in axial alignment with BOP stack and said pipe string and wherein said first gripping unit is positioned above said second gripping unit; (c) moving said first and said second pipe gripping units away from each other along said guide rails; (d) closing said pipe gripping mechanism of said second pipe gripping unit thereby gripping said pipe string with said second gripping unit while opening said gripping mechanism of said first pipe gripping unit; (e) positioning a pipe through said central opening of said snubbing jack whereby said pipe is laterally supported by said guiderails; (f) attaching said pipe to said pipe string; (g) closing said pipe gripping mechanism of said first pipe gripping unit thereby gripping said pipe attached to said pipe string with said first gripping unit while synchronously opening said gripping mechanism of said second pipe gripping unit; and (h) moving said second pipe gripping unit upward along said guide rails toward said first pipe gripping unit while synchronously moving said first pipe gripping unit downward along said guide rails toward said second pipe gripping unit and said BOP stack and thereby pushing said pipe attached to said pipe string through said BOP stack into said wellbore.

16. The method of snubbing a length of pipe into a wellbore through a BOP stack of claim 15, comprising the additional steps of: (a) closing said pipe gripping mechanism of said second pipe gripping unit thereby gripping said pipe attached to said pipe string with said second gripping unit while opening said gripping mechanism of said first pipe gripping unit to release said pipe attached to said pipe string; and (b) moving said first pipe gripping unit upward away from said second pipe gripping unit while synchronously moving said second pipe gripping unit downward along said guide rails toward said BOP stack and thereby pushing said pipe attached to said pipe string through said BOP stack into said wellbore.

17. The method of snubbing a length of pipe into a wellbore through a BOP stack recited in claim 16 wherein said first pipe gripping unit is operative connected to a first linear actuator and said second pipe gripping unit is operatively connected to a second linear actuator, and the first and second gripping units are moved toward and away from each other by operation of the first linear actuator, operation of the second linear actuator, or operation of a combination of the first and second linear actuators.

18. The method of snubbing a length of pipe into a wellbore through a BOP stack recited in claim 17 wherein said linear actuator is a hydraulic cylinder with an extendable and retractable piston rod.

19. The method of snubbing a length of pipe into a wellbore through a BOP stack recited in claim 17 wherein said linear actuator includes a rack and pinon mechanism.

20. The method of snubbing a length of pipe into a wellbore through a BOP stack recited in claim 19 wherein said first pipe gripping unit and said second pipe gripping unit has a slip pipe gripping mechanism.

Description

DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is perspective view of the duplex snubbing jack described herein.

(2) FIG. 2 is as elevation side view of the duplex snubbing jack shown in FIG. 1 with the upper and lower gripping units in their outmost position.

(3) FIG. 3 is a cross-section side view of the duplex snubbing jack shown in FIG. 1 with the upper and lower gripping units in their inmost position.

(4) FIG. 4 is a detail cross-section side view of a pipe gripping mechanism of a gripping unit.

(5) FIG. 5 is a cross-section side view of an alternate embodiment of the duplex snubbing jack with the upper gripping unit in its outmost position.

(6) FIG. 6 is a cross-section side view of an alternate embodiment of the duplex snubbing jack shown in FIG. 5 with the upper gripping unit in its inmost position.

DESCRIPTION OF THE EMBODIMENTS

(7) In the drawings, well established features that do not bear upon points of novelty are omitted in the interest of descriptive clarity. Such omitted features may include threaded junctures, weld lines, sealing elements, pins, and the like.

(8) FIGS. 1 through 3 show an embodiment of the duplex snubbing jack (100). As shown, the duplex snubbing jack (100) has a first or upper pipe gripping unit (110) and a second or lower pipe gripping unit (120). The pipe gripping units (110) and (120) are shown as similarly configured slip-type pipe gripping units but other types of pipe gripping units or assemblies might also be utilized. The pipe gripping units (110) and (120) are positioned between a base to (112), which may be a base plate as shown or a framework of structure members such as beams and plates, and a cap (114), shown as a plate but which may also be a framework of structure members such as beams and plates, that are separated by a plurality of support rails (115).

(9) The support rails (115) are positioned around a central opening (116) that extends through the duplex snubbing jack (100). The central opening (116) of the duplex snubbing jack (100) includes base opening (116a) in the base (112), cap opening (116b) in the cap (114), gripping unit opening (116c) through the first pipe gripping unit (110), and gripping unit opening (116d) through the second pipe gripping unit (120) which are all in co-axial alignment with each other. The base (112) has an attachment flange (113), or an attachment flange-hole configuration, around base central opening (116a) that allows the duplex snubbing jack (100) to be positioned in co-axial alignment onto or adjacent to a BOP stack (300) or other wellhead device through which pipe may be inserted into a wellbore. The central opening (116) allows pipe to be extended the entire length of the duplex snubber (100) along the rails (115) though the central opening (116a) of the base (112) and the central opening (116b) of the cap (114).

(10) As shown in FIGS. 1-3 the first pipe gripping unit (110) and the second pipe gripping unit (120) each have a pipe gripping mechanism (117) whereby a length of pipe (P) may be selectively gipped or released. As shown, pipe gripping mechanism (117) may be opened to release a length of pipe (P) or closed to grip a length of pipe (P) within their respective central openings (116c) and (116d) whereby a length of pipe (P) may be gripped or released as desired.

(11) Gripping mechanism (117) with a slip-type pipe gripping mechanism is shown in detail in FIG. 4. The slip-type pipe gripping mechanism includes a plurality of gripping slips (118) that may be moved radially inward (closed) and outward (opened) whereby a length of pipe (P) may be gripped or released as desired. As shown, the pipe gripping slips (118) are moved by manipulation of extendable and retractable piston rods (123) of hydraulic or pneumatic cylinders (121) mounted between upper and lower timing rings (125) which are pivotally attached by links (128) to the pipe gripping slips (118) that are slidably mounted on inwardly tapered slip supports (127). Extension of the piston rods (123) will move the pipe gripping slips (118) radially outward or open with respect to central openings (116c) or (116d) as the pipe gripping slips (118) slide along the slip supports (127). Retraction of the piston rods (123) will move the pipe gripping slips (118) radially inward or closed with respect to central openings (116c) or (116d) as the pipe gripping slips (118) slide along the slip supports (127). Similar slip-type pipe gripping mechanisms are described in Applicant's U.S. Pat. No. 7,775,270 entitled Spider With Distributed Gripping Dies and in Applicant's U.S. Pat. No. 7,267,168 entitled Spider With Discrete Die Supports.

(12) To move the first and second pipe gripping units (110) and (120), a first gripping unit positioning linear actuator (130) having a jack rod (131), or a plurality of such first gripping unit positioning linear actuators (130), is mounted on the base (112) with jack rod (131) attached to the first pipe gripping unit (110). A second gripping unit positioning linear actuator (132) having a jack rod (133), or a plurality of such second gripping unit linear actuators (132), is mounted on the base (112) with jack rod (133) attached to the second pipe gripping unit (120). A suitable positioning linear actuator (130), (132) may be a hydraulic or pneumatic cylinder having an extendable and retractable piston rod or jack rod, a rack and pinion mechanism with a motor for extending and retracting a jack rod or jack plate, or a screw jack and motor mechanism for extending and retracting a jack rod.

(13) In operation, the base (112) of the duplex snubbing jack (100) will be mounted above the BOP stack (300) by mean of attachment flange (113) so that the central opening (116) of the duplex snubbing jack is aligned with the central opening of the BOP stack (300). The first pipe gripping unit (110) and the second ripping unit (112) are then situated at their outmost positions with respect to each other by extension of the jack rod (131) of the first gripping unit positioning linear actuator (110) and by retraction of the jack rod (133) of the second pipe gripping unit linear actuator (120) as shown in FIGS. 1 and 2. When situated at their outmost position, the second pipe gripping unit (120) is at its lowest position with respect to the BOP stack and the first pipe gripping unit (110) is at its extreme upward position away from the second pipe gripping unit (120) and BOP stack (300).

(14) Retraction of the jack rod (131) of the first gripping unit positioning linear actuator (130) and extension of the jack rod (131) of the second pipe gripping unit linear actuator (133) will synchronously move the first pipe gripping unit (110) and the second pipe gripping unit (120) to their inmost position with respect to each other as shown in FIG. 3. When situated at such inmost position, the second pipe gripping unit (120) will have moved upwardly along the guide rails (115) to its upmost position just below the horizontal mid-line of the duplex snubbing jack (100) and the first pipe gripping unit (110) will have moved downwardly along the guide rails (115) to its lowest position just above the horizontal mid-line of the duplex snubbing jack (100). In a normal operating sequence of the duplex snubbing jack (100), the first pipe gripping unit (110) and second gripping unit (120) will always move synchronously toward or away from each other, never independently.

(15) When attaching a pipe (P) to a wellbore pipe string (PS) and running the running pipe (P) through the BOP stack (300) into a wellbore, the pipe (P) is positioned through the central opening (116) of the duplex snubbing jack (100). The first pipe gripping unit (110) and the second unit (120) are synchronously moved to their outmost position away from each other by extension of the jack rod (131) of the first gripping unit positioning linear actuator (130) and by retraction of the jack rod (133) of the second pipe gripping unit positioning linear actuator (132).

(16) The pipe gripping slips (118) of the lower second gripping unit (120) are then closed by moving the pipe gripping slips (118) radially inward in the central opening (116d) of the second pipe gripping unit (120) to grip the wellbore pipe string (PS) while the pipe gripping slips (118) of the upper gripping unit (120) are synchronously opened by moving the pipe gripping slips (118) of the first pipe gripping unit (110) radially outward in the central opening (116c) of the first pipe gripping unit (110) to allow a length of pipe (P) to be inserted through the central opening (116) of the duplex snubbing jack (100) where it may be attached to the wellbore pipe string (PS).

(17) When the length of pipe (P) is attached to the wellbore pipe string (PS), the pipe gripping slips (118) of the first pipe gripping unit (110) are closed by moving the pipe gripping slips (118) of the first pipe gripping unit (110) radially inward in the central opening (116c) of the first gripping unit to grip the length of pipe (P) now attached to the wellbore pipe string (PS) while the gripping slips of the second pipe gripping unit (120) are synchronously opened by moving the pipe gripping slips (118) of the second pipe gripping unit radially outward in the central opening (116d) of the second pipe gripping unit (120) to release the wellbore pipe string (PS).

(18) The first pipe gripping unit (110) and the second pipe gripping unit (120) are then synchronously moved downwardly and upwardly, respectively, to their inmost position toward each other by retraction of the jack rod (131) of the first gripping unit positioning linear actuator (130) and extension of the jack rod (133) of the second gripping unit positioning linear actuator (132). The downward movement of the first pipe gripping unit (110) toward its inmost position will then run the length of pipe (P) attached to the wellbore pipe string (PS) through the central opening (116d) of the second pipe gripping unit (120) and snub the length of pipe (P) through the BOP stack (300) and into the wellbore.

(19) The pipe gripping slips (118) of the second pipe gripping unit (120) are then closed as previously described to grip the length of pipe (P) and then attached wellbore pipe string (PS) while the gripping slips of the first pipe gripping unit (110) are synchronously opened as previously described to release the length of pipe (P) and the attached wellbore pipe string (PS). The first pipe gripping unit (110) and the second pipe gripping unit (120) are then synchronously moved upwardly and downwardly, respectively, to their outmost position away from each other by extension of the jack rod (131) of the first positioning linear actuator (130) and retraction of the jack rod (133) of the second positioning linear actuator (132). The downward movement of the second pipe gripping unit (120) will further push the length of pipe (P) and the attached wellbore pipe string (PS) into the wellbore. This process may then be repeated to snub or run additional lengths of pipe into the wellbore.

(20) The guide rails (115) of the duplex snubbing jack (100) support the length of pipe (P) being snubbed into the wellbore along its entire length. The lateral support of pipe (P) being snubbed provided by the guide rails will reduce the incidence of pipe buckling as the length of pipe is pushed through the BOP stack by the reciprocal movement of the gripping units.

(21) When pulling pipe (P) from a wellbore through BOP stack (300), the duplex snubbing jack (100) is mounted above the BOP stack around the axis of a wellbore pipe string as described above for running pipe. The first or upper gripping unit (110) and the second or lower gripping unit (120) are synchronously moved to their outmost position away from each other by extension of the jack rod (131) of the first positioning linear actuator (130) and retraction of the jack rod (133) of the second positioning linear actuator (132). The pipe gripping slips (118) of the second pipe gripping unit (120) are then closed by moving the pipe gripping slips (118) of the second pipe gripping unit (120) radially inward in the central opening (116d) of the second pipe gripping unit to grip the wellbore pipe string (PS) while the pipe gripping slips (118) of the first pipe gripping unit (110) are synchronously opened by moving the pipe gripping slips (118) of the first gripping unit radially outward in the central opening (116c) of the first pipe gripping unit (110) to allow the first gripping unit to be moved along the length of the pipe (P) being pulled.

(22) The first pipe gripping unit (110) and the second pipe gripping unit (120) are then synchronously moved downwardly and upwardly, respectively, to their inmost position toward each other by retraction of the jack rod (131) of the first positioning linear actuator (130) and extension of the jack rod (133) of the second positioning linear actuator (132). The upward movement of the second pipe gripping unit (120) toward its inmost position will then pull the length pipe (P) and the attached wellbore pipe string (PS) through the BOP stack (300) from the wellbore. The pipe gripping slips (118) of the first ripping unit (110) are then closed as previously described to grip the length of pipe (P) while the gripping slips of the second or lower gripping unit are synchronously opened as previously described to release the wellbore pipe string (PS). The first pipe gripping unit (110) and the second pipe gripping unit (120) are then synchronously moved upwardly and downwardly, respectively, to their outmost position away from each other by extension of the jack rod (131) of the first positioning linear actuator (130) and retraction of the jack rod (133) of the second positioning linear actuator (132). The upward movement of the first pipe gripping unit (110) will further pull the length of pipe (P) and the attached wellbore pipe string (PS) from the wellbore through the BOP stack (300). The attached length of pipe (P) may then be removed from the wellbore pipe string (PS). This process may then be repeated to pull or remove additional lengths of pipe from the wellbore through the BOP stack (300).

(23) FIGS. 5 and 6 show a second embodiment of the duplex snubbing jack designated as duplex snubbing jack (200). In this second embodiment, snubbing jack (200) has the same first and second gripping units (110) and (120), respectively, which operate to grip and release pipe in the same manner as that shown described above for embodiment of duplex snubbing jack (100). Snubbing jack (200) also has an essentially the same base (112), cap (114), rails (115), and central opening (116) as that described above for duplex snubbing jack (100) except for perhaps for variations in size that might be necessary to accommodate attachment of an alternate to gripping unit positioning actuator (110) shown in FIGS. 1-3 and described above. Base (112) of duplex snubbing jack (200) is also configured for attachment to BOP stack (300) bye means of an attachment flange (113) at the base (112) as described for duplex snubbing jack (100).

(24) However, for duplex Snubbing jack (200), the lower gipping unit (120) is fixed in position on the base (112) and remains stationary throughout the pipe snubbing process. The upper gripping unit (110) is moveably positioned axially along duplex snubbing jack (200), upward and downward, such as by a linear actuator (230). In this alternate embodiment, the linear actuator (230) of snubbing jack (200) is shown as a rack and pinion mechanism (232) with a motor for (240) for rotating a pinon gear (242) that engages with a gear rack (244) on a jack rod or jack plate (246) attached to the first pipe gripping unit (110). A suitable linear actuator (230) may also be a hydraulic or pneumatic cylinder having an extendable and retractable piston rod or jack rod or a screw jack and motor mechanism for extending and retracting a jack rod.

(25) In operation of duplex snubbing jack (200), lower second gripping unit (120) stays in place and the upper first pipe gripping unit (110) is moved upward and downward with respect to gripping unit (120) and BOP stack (300). As shown in FIG. 5, first pipe gripping unit (110) may be moved to its extreme upward position away from gripping unit (120) and BOP stack (300) by rotating pinon gear (242) to engage with a gear rack (244) on a jack rod or jack plate (246) to move the attached first pipe gripping unit (110) upward to its extreme upward position with respect to first gipping unit (120) and BOP stack (300). Rotating pinon gear (242) in the opposite direction will engage gear rack (244 on a jack rod or jack plate (246) to move upper gripping unit (110) downward from its extreme upward position to its extreme lowest position just above the lower second gripping unit (120) as shown in FIG. 6. In its normal operating sequence, the first pipe griping unit (110) will always move toward or away from second gripping unit (120) and second gripping unit (120) never moves.

(26) When pulling a length of pipe (P) attached to a wellbore pipe string (PS) from a wellbore through BOP stack (300), the pipe gripping slips (118) of the second pipe gripping unit (120) are closed by moving the pipe gripping slips (118) of the second pipe gripping unit (120) radially inward to grip the wellbore pipe string (PS) while the pipe gripping slips (118) of the first pipe gripping unit (110) are synchronously opened by moving the pipe gripping slips (118) of the first pipe gripping unit (110) radially outward to release the pipe (P) of the attached wellbore pipe string (PS) and the upper gripping unit (110) moves downwardly along the length of the pipe (P) of the attached wellbore pipe string (PS).

(27) When the first pipe gripping unit (110) reaches its terminal downward position just above the second pipe gripping unit (120), the pipe gripping slips (118) of the first pipe gripping unit (110) are closed by moving the pipe gripping slips (118) of the first pipe gripping unit (110) radially inward to grip the length of the pipe (P) of the attached wellbore pipe string (PS) and the pipe gripping slips (118) of the second pipe gripping unit (120) are synchronously opened by moving the pipe gripping slips (118) of the second pipe gripping unit (120) radially outward to release the pipe (P) of the attached wellbore pipe string (PS). The first pipe gripping unit (110) then moves upward toward its extreme upward position with respect to the second pipe gripping unit (120) and the BOP stack (300); pulling the length of the pipe (P) and the attached wellbore pipe string (PS) from the wellbore through the BOP stack (300).

(28) The method for pulling a length of pipe (P) attached to a wellbore pipe suing (PS) from a wellbore through BOP stack (300) described above for use of duplex snubbing jack (200) may be repeated to pull or remove additional lengths of pipe (P) from the wellbore through the BOP stack (300). The method may also be reversed for attaching a length of pipe (P) to a wellbore pipe string (PS) and snubbing or running the attached length of (P) into the wellbore through the BOP stack (300).

(29) As noted above for the first embodiment of duplex snubber (100), the rails (115) of the duplex snubbing jack (200) are positioned around central opening (116) of the duplex snubbing jack (200) and adjacent the length of the pipe (P) of the attached wellbore pipe suing (PS) to support the length of pipe (P) when it is being run into or pulled from the wellbore through the BOP stack (300).

(30) Among the advantages of the duplex snubbing jacks (100) and (200) is faster operation over conventional snubbing units because longer lengths of pipe (P) may be snubbed due to the support provided by the guide rails (150). This also results in gripping, releasing, and re-gripping of the pipe gripping slips (118) of the pipe gripping units (110) and (120) and less wear or on their gripping faces.