AU2012201018B2 - Improved running adapter - Google Patents

Abstract

Abstract A plug for sealing a conduit comprises a body having a first section (15) and a second section (17), and at least one seal element (20) for creating a seal between the plug and the conduit. The at least one seal element (20) is adapted to be energised by movement in a setting direction of the first body section (15) relative to the second body section (17). The pug further comprises seal locking means (26) comprising a first portion and a second portion wherein as the at last one seal (26) is energised, the seal locking means first portion is rotatable unidirectionally relative to the seal locking means second portion to take up the movement of the first body section (15) relative to the second body section (17) in the setting direction and prevent movement of the first body section relative to the second body section in a releasing direction, opposite the setting direction. In one embodiment the seal locking means first portion is a locking nut

Description

Regulation 3.2 AUSTRALIA PATENTS ACT, 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT ORIGINAL Name of Applicant: PETROWELL LIMITED Actual Inventors: PURKIS, Daniel Address for service in A J PARK, Level 11, 60 Marcus Clarke Street, Canberra ACT Australia: 2601, Australia Invention Title: Improved running adapter The following statement is a full description of this invention, including the best method of perfonning it known to us. 3821912_1 2 IMPROVED RUNNING ADAPTER FIELD OF THE INVENTION The present invention relates to plugs, particularly to plugs for sealing 5 wellbores and christmas trees. BACKGROUND OF THE INVENTION Conventionally wellbores, and christmas trees associated with wellbores, have been sealed with plugs having three basic parts: an anchoring system, a sealing 10 element and a setting system. The first stage in setting a conventional plug is anchoring the plug in the wellbore. Anchoring systems for conventional wellhead plugs use a set of locking dogs, which engage a recessed profile in the wellbore or tree, or use a set of slips which "bite" the casing to hold the plug in place. 15 The seal is then set using a linear action setting mechanism to create a linear displacement to defonn the seal element. The force required to create the seal is then locked in using a linear locking mechanism. In wellbore applications the seal is generally a metal-to-metal seal formed by swaging a metal ring element into the bore or onto a no-go shoulder. 20 To provide a seal capable of withstanding well pressures, the required setting force needs to be as high as the maximum force generated by the well pressure. In recent years a number of high pressure, high temperature, high flow rate wells have been completed which have highlighted shortcomings in conventional designs of well bore plugs and tree plugs. For example, swaged seals can dislodge 25 when exposed to the high pressure, temperature and vibration cycles of these wells, and the jarring action used to set the seal can damage the plug or the surrounding environment. Additionally, linear locking mechanisms have a degree of backlash which in a high temperature, pressure and vibration cycle environment can lead to failure. 30 A further disadvantage of conventional plugs is the expansion achievable from the metal seal element is not sufficient to permit the plug to be run into the wellbore with adequate clearance between the plug and the wellbore to prevent a build-up of pressure in front of the plug, resisting the placement of the plug. This can be a 3820582-1 3 particular problem when a number of plugs are to be located in series in a conduit, as a hydraulic lock can be formed between plugs. It is an object of the present invention to obviate or mitigate at least one of the aforementioned disadvantages. 5 SUMMARY OF THE INVENTION According to a first aspect of the present invention there is provided a running adapter for setting a plug in a conduit which extends downhole, the running adapter being adapted to be releasably connected to a plug and arranged to convert a rotary 10 input force into a rotary and an axial output force. Preferably, the rotary output force is provided separately from the axial output force. In one embodiment, the adapter comprises an input mandrel, an output mandrel, an adapter casing, and a locking sleeve. 15 Preferably, the adapter is arranged such that rotation of the input mandrel causes axial movement of the output mandrel relative to the adapter casing, and causes rotational movement of the locking sleeve. Preferably, the input mandrel is adapted to be connected to a rotary drive. Preferably, the adapter casing is adapted to engage a plug first body section. 20 Preferably, the output mandrel is adapted to engage a plug second body section. Preferably, the locking sleeve is adapted to engage a plug seal locking means. Preferably, the locking sleeve is adapted to selectively engage the input mandrel. Most preferably, the locking sleeve is adapted to selectively rotate with the 25 input mandrel. Preferably, the running adapter further comprises a locking sleeve clutch to disengage the locking sleeve from the input mandrel. Preferably, the adapter casing is connected to the input mandrel by a threaded connection. Using a threaded connection converts rotation of the input mandrel to 30 axial movement of the adapter casing with respect to the input mandrel. Preferably, the output mandrel is axially fixed to the input mandrel. Most preferably, the output mandrel is rotationally independent of the input mandrel. 3820582-1 4 Preferably, a bearing interface is provided between the input mandrel and the output mandrel. A bearing interface permits the input mandrel to rotate with respect to the output mandrel. Preferably, the output mandrel includes a bearing surface. There is the 5 possibility that the bearing interface between the input and output mandrels might fail, in this case the output mandrel would rotate. If the output mandrel is directly or indirectly attached to a plug second body section, a bearing surface will reduce the possibility of damage to the second body section. Preferably, the running adapter further comprises a latch, the latch being 10 adapted to be located, in use, between the output mandrel and a plug second body section. In an alternative embodiment, the running adapter comprises a tubular member having a longitudinal axis, an outer surface and an inner surface, one of the outer surface or the inner surface adapted to engage a portion of a plug seal setting 15 means to set an at least one plug seal element, wherein the at least one plug seal element is set by rotation of the running adapter in a first direction about the longitudinal axis. Preferably, the running adapter is adapted to disengage from the plug seal setting means when rotation about the longitudinal axis is in a direction opposite to 20 the first direction. Preferably, the inner surface of the tubular member is adapted to engage a portion of an external surfice of the plug seal setting means. Preferably, the inner surface of the tubular member is adapted to engage the plug seal setting means by means of at least one first engagement element, the at least 25 one first engagement element adapted to engage with at least one first complementary notch in the portion of the external surface of the plug seal setting means to rotate the plug seal setting means. Preferably, the at least one first engagement element is arranged only to engage the at least one first complementary notch when rotation is in the first 30 direction. The at least one first engagement element may be pivotally mounted in an at least one first recess in the tubular member, the at least one first engagement element being biased to a position in which the at least one first engagement element sits proud of the iimer surface of the tubular member, such that when rotation is in the 3820582-1 5 opposite direction the outer surface of the plug seal setting means depresses the at least one first engagement member into the at least one first tubular member recess. The outer surface of the running adapter tubular member may be adapted to engage with a portion of the internal surface of an inner plug anchor setting means to 5 set at least one plug anchor, wherein the at least one plug anchor is set by rotation of the running adapter in the opposite direction about the longitudinal axis. Preferably, the running adapter is disengaged from the plug anchor setting means when rotation about the longitudinal axis is in the first direction. Preferably, the outer surface of the tubular member is adapted to engage the 10 plug anchor setting means by means of at least one second engagement element, the at least one second engagement element adapted to engage with at least one second complementary notch in the portion of the internal surface of the plug anchor setting means to rotate the anchor setting means. Preferably, the at least one second engagement element is arranged only to 15 engage the at least one second complementary notch when rotation is in the opposite direction. The at least one second engagement element may be pivotally mounted in an at least one second recess in the tubular member, the at least one second engagement element being biased to a position in which the at least one second engagement 20 element sits proud of the outer surface of the tubular member, such that when rotation is in the first direction the inner surface of the plug anchor setting means depresses the at least one second engagement member into the at least one second tubular member recess. The adapter described in the alternative embodiment will set a plug by firstly 25 setting the plug anchors by rotating the adapter in one direction, and then set the plug seal by rotating the adapter in the other direction. BRIEF DESCRIPTION OF THE DRAWINGS The present invention will now be described, by way of example, with 30 reference to the accompanying figures in which: Figure 1 is a cut away side view of a plug, for sealing a conduit, and a running adapter for setting the plug in the conduit in accordance with a first embodiment of the present invention; 3e20582-1 6 Figure 2 is an enlarged cut away side view of section A of Figure 1, showing the plug and part of the running adapter; Figure 3 is an enlarged cut away side view of section B of Figure 1, showing part of the running adapter; 5 Figure 4 is an enlarged cut away side view of section C of Figure 1, showing part of the running adapter; Figure 5 is a cut away side view of the plug of Figure 1 in a conduit prior to the anchoring dogs being set; Figure 6 is a cut away side view of the plug of Figure 1 in the conduit after the 10 anchoring dogs have been set and prior to the seal element being set; Figure 7 is a cut away side view of the plug of Figure 1 in the conduit after the anchoring dogs and the seal element have been set; Figure 8 is a cut away side view of the plug of Figure 1 in the conduit showing the retaining sleeve disengaged from the locking nut; 15 Figure 9 is a cut away side view of the plug of Figure 1 in the conduit showing the seal element released; Figure 10 is a cut away side view of the plug of Figure 1 in the conduit showing the anchoring dogs released; Figure 11 is a perspective view of a locking nut; 20 Figure 12 is a view along section A-A of Figure 2 through part of the locking nut; Figure 13 is a perspective view of one of the first conical washers of the seal element; Figure 14 is a schematic cut away side view of part of a stack of frusto-conical 25 washers in an uncompressed configuration; Figure 15 is a schematic cut away side view of part of a stack of frusto-conical washers in a compressed configuration; Figure 16 is a perspective view of part of the plug mandrel; Figure 17 is a perspective view of a plug for sealing a conduit in accordance 30 with a second embodiment of the present invention; Figure 18 is a sectional view of the plug of Figure 1 taken through line A-A on Figure 17; Figure 19 is a sectional view taken through line B-B on Figure 18; Figure 20a is a perspective view of the first rotary lock ring of Figure 18; 3820582-1 7 Figure 20b is a plan view of the second rotary lock ring of Figure 18; Figure 21 is a perspective view of a plug running adapter for setting a plug in a conduit in accordance with a second embodiment of the present invention; Figure 22 is a sectional view taken through line C-C on Figure 21; and 5 Figure 23, comprising Figures 23a to 23d is a schematic of the plug of Figure 17 being set in a wellbore. DETAILED DESCRIPTION OF THE DRAWINGS Referring firstly to Figure 1 there is shown a cut away side view of a plug, 10 generally indicated by reference numeral 10 for sealing a conduit (not shown), and a running adapter 12 for setting the plug 10 in the conduit. As can be seen from Figure 1 the plug and running adapter 10,12 had been divided into three sections indicated as "A", "B", and "C", each of these sections is shown in Figures 2, 3 and 4 respectively. 15 Referring to Figure 2, an enlarged cut away side view of section A of Figure 1, showing the plug 10 and part of the running adapter 12. The plug 10 includes a housing 14, divided in to a moveable upper housing section 15 and a fixed lower housing section 17. The plug 10 also includes a seal setting means 16 in the form of a plug mandrel 18 and a seal element 20 in the form 20 of a stack of frusto-conical washers 22. The plug 1.0 includes eight anchoring dogs 34 for anchoring the plug 10 in the conduit (not shown). The dogs 34 are axially restrained by the lower housing section 17 but are pennitted to move radially outwards from the housing 14 through a series of openings 36. 25 The dogs 34 are moved radially outwards through the apertures 36 by the upper housing section 15, specifically, by the action of a housing ramp 54. The plug 10 further comprises a seal and anchor locking means 24 comprising a locking nut 26, a spacer sleeve 28, and a retaining sleeve 30. The retaining sleeve 30 is releasably fixed to the locking nut 26 by means of a number of sheer screws 32, of 30 which one is indicated. The locking nut 26 is attached to the plug mandrel 18 by a threaded connection 27, and the spacer sleeve acts on the housing upper portion 14, specifically the housing ramp 54. It will be understood that the spacer sleeve 28 could be part of the housing 14. 3820582-1 8 The seal and anchor locking means 24 permits movement of the housing upper portion 15 relative to the mandrel 18 in a setting direction, that is a direction which the seal element 20 is energised, but not in a releasing direction, opposite the setting direction. 5 Referring to Figures 3 and 4, enlarged cut away side views of sections B and C of Figure 1 showing the running adapter 12, the adapter 12 is arranged, in use with the plug 10, to convert a rotary input force applied to an input mandrel 80 into a rotary and an axial output force for application to the plug 10. The rotary output force is applied to the locking nut 26 by a locking sleeve 82, and the axial output force is 10 applied to the upper housing section 15 by a running adapter casing 86, and to the plug mandrel 18 by an output mandrel 84. The setting of the plug 10, by the plug and the running adapter 12 will now be described with reference to Figures 1 to 4, and Figures 5 to 7. Figure 5 to 7 are cut away views of the plug 10 being set in a conduit 90. For clarity, the running adapter 15 12 is not shown in any of Figures 5 to 7. The plug and adapter 10,12 are lowered into the conduit 90, in this case the bore of a christmas tree. As can be seen from Figure 5, the stack of washers 22 is arranged so that the washers 22 do not extend beyond the circumference housing lower section 17. This permits the plug 10 to be run in to the conduit 90 without 20 damaging the seal element 20. The plug 10 is run into the conduit 90 until a housing shoulder 92 engages a conduit no-go 94, indicating the plug 10 has reached the correct location. At this point the adapter 12 can be activated and the plug 10 can be set. A rotary force is applied to the running adapter input mandrel 80 by an 25 external drive (not shown). The running adapter input mandrel 80 engages the running adapter casing 86 by means of a threaded connection 96. The threaded connection 96 has a pitch of0.2 inches (0.508 mm). The running adapter casing 86 is locked to a motorised setting tool (not shown) connected to the running adapter 12, preventing the casing 86 from rotating 30 with the input mandrel 80. However linear axial movement of the running adapter casing 86 is permitted. The threaded connection 96 is arranged such that rotational movement of the input mandrel 80, in the absence of a resistance, would result in the input mandrel 80 moving the direction of arrow "X" (Figure 4), applying a pulling 3820582-1 9 force on the output mandrel 80, and the casing moving in the direction of arrow "Y", that is pushing on the upper housing section 15. There is however a resistance preventing the input mandrel 80 moving in the direction is arrow "X". The input mandrel 80 is connected to a collar 98 (Figure 3), 5 which is in turn connected to the output mandrel 84 via a number of shear screws 100. A pair of roller bearings 102 permit the input mandrel 80 to rotate within the collar 98 whilst still transmitting axial pulling forces, applied by the input mandrel 80, to the output mandrel 84. The output mandrel 84 is in turn connected to the plug mandrel 18 by means of a collet 104 (Figure 2). The pulling force applied to the plug mandrel 10 18 by the input mandrel 80, via the collar 98 and the output mandrel 84 is resisted by a set of shear set screws 106. The resistance of the shear set screws 106 prevents the input mandrel moving in the direction of arrow "X" and therefore the running adapter casing 86 moves in the direction of arrow "Y" and applies an axial "pushing" force on the upper housing 15 section 15. Referring to Figure 5, a cut away side view of a plug 10 in a conduit 90 prior to the dogs 34 being set, under the action of this force, the upper housing section 15 and the housing ramp 54 move in the direction of arrow "Y", the ramp 54 engaging the dogs 34 and pushing them radially outwards through the housing apertures 36. 20 The dogs 34 move towards engagement with a complementary recess 108 in the conduit wall 110. The ramp 54 defines a variable surface taper 55 having two sections 57 of shallow taper and two sections 59 of steep taper. The steep taper sections 59 are arranged to move the dogs 34 rapidly towards the conduit recess 108, with the shallow taper sections 57 pushing the dogs 34 for the final stage of their 25 travel into the recess 108 and into engagement with the conduit wall 110. A shallow taper for the stage of the travel in which actual engagement occurs is preferred because a shallow taper maximises the radial force applied to the dogs 34 and assists in locking the plug 10 in the conduit 90. Utilising the steep taper sections 59 for the initial expansion of the travel reduces the axial length of the ramp 54. 30 The movement of the upper housing section 15 relative to the plug mandrel 18 is taken up by the locking nut 26, which engages the plug mandrel 18 by means of the threaded connection 27. As the upper housing section 15 moves relative to the plug mandrel 18, the locking nut 26 is rotated by the running adapter locking sleeve 82 relative to the spacer sleeve 28. This rotation is unidirectional preventing relative 3820582-1 10 movement of the mandrel 18 with respect to the upper housing section 15 in the opposite direction, which, if permitted, would release the seal element 20. The locking sleeve 82 is connected to the input mandrel 80 by a clutch 112 (Figure 4). As the input mandrel 80 rotates the locking sleeve 82 rotates, however if 5 the locking sleeve 82 encounters sufficient resistance, the clutch 112 slips and the rotation of the locking sleeve 82 stops. The pitch of the threaded connection 27 between the locking nut 26 and the plug mandrel 18 is 0.25 inches (6.35 mm), compared to the pitch of the threaded connection between the input mandrel 80 and the adapter casing 86 of 0.2 inches (5.08 mm). This difference in the two pitches 10 means that for every revolution of the input mandrel 18, the adapter casing 86, and hence the upper housing section, will move 0.2 inches (5.08 mm), and the locking nut will move 0.25 inches (6.35 mm). However as the locking nut 26 is acts on upper housing section 15 via the spacer sleeve 28, the full movement of the locking nut 26 per revolution of the input mandrel 18 is not permitted and sufficient resistance is 15 generated on the locking sleeve 82 to slip the clutch 112. The locking sleeve 82, however, applies a continual rotational force to the locking nut 26 and as soon as there is further movement of the upper housing section 15 relative to the plug mandrel 18, the locking nut 26 will take up this movement. Referring now to Figure 11, a perspective view of the locking nut 26, it can be 20 seen the locking nut comprises a first locking nut portion 56 and a second locking nut portion 58. The first locking nut portion 56 comprises six axial sections 60, each axial section 60 being attached to the second locking nut portion 58 by means of a dovetail connection 62. The internal surfaces 61 of the six axial sections 60, when assembled, define one half of the threaded connection 27, The dovetail connections 25 62 permit the axial sections 60 to move in a radial direction relative to the second locking nut portion 58 but not in an axial direction. When the seal locking means 24 is assembled the axial sections 60 are prevented from moving radially outwards by the retaining sleeve 30. The locking nut 26 also includes unidirectional locking device 64. The 30 arrangement of each locking device 64 can be seen more clearly in Figure 12, a view along section A-A of Figure 2 Each locking device 64 comprises a ball bearing 66 located in a channel 68 having an internal surface 74. The ball bearing 66 is mounted on a spring 70 which pushes against the ball bearing 66, forcing the ball bearing 66 out of the channel 68. 3820582-1 11 As the locking nut 26 rotates with respect to the spacer sleeve 28, the ball bearing 66 is pressed against the spacer sleeve surface 72. If the locking nut 26 is moving relative to the spacer sleeve 28 in the direction of arrow "A", the ball bearing is pushed back up the channel 68, however if a force is applied to the locking nut 26 5 in the direction of arrow "B", then the ball bearing 66 is drawn out of the channel 68 and wedges between the sleeve surface 72 and the channel surface 74, preventing further movement in the direction of arrow "B". As the interface between the locking nut 26 and the spacer sleeve 28 is located on an are centred on, and substantially perpendicular to, the longitudinal axis of the adapter, backlash is minimised. For 10 example if the locking nut moved 1/20 of a revolution in the direction of arrow "B", this would result in axial movement in the release direction of (0.25 x 1/20) inches, that is 0.0125 inches (0.318 mm). The motorised setting tool (not shown) records the torque versus turn profile of the locking nut 26. This information is transmitted live by e-line (not shown) from the adapter 12 and compared with the expected profile 15 in order to confirm proper setting of the plug. Referring now to Figure 6, a cut away side view of the plug 10 in the conduit 90 after the anchoring dogs 34 have been set and prior to the seal element 20 being set, the dogs 34 have engaged the recess 108, particularly, a first dog surface region 112 has engaged a first recess surface region 114. This arrangement imparts a 20 downward force on the plug 10 which is resisted by the interaction between the plug shoulder 92 and the conduit no-go 94, with the result that the plug 10 is firmly locked in the conduit 90. With the dogs 34 fully set, the upper housing section 15 can not move any further in the direction of arrow "Y". Once the plug 10 is firmly locked in position, the seal element 20 can be set. 2 5 This is achieved by increasing the rotary force on the input mandrel 80. Referring to Figure 7, a cut away side view of the plug 10 in the conduit 90 after the anchoring dogs and the seal element 20 have been set, the force is increased on the input mandrel 80 until the shear screws 106 shear, permitting the input mandrel 80, and hence the plug mandrel 18, to move in the direction of arrow "X". 30 The seal element 20 is located in a seal recess 116 defined by the plug mandrel 18 and the lower housing section 17. As the plug mandrel 18 moves upwards, that is in the direction of arrow "X", the seal recess 116 reduces in size, coinpressing the seal element 20 into engagement with the conduit 90. 3820582-1.

12 The movement of the plug mandrel 18 relative to the housing 14 is taken up by the locking nut 26, which is driven by the running adapter locking sleeve 82, in the same way as described previously. As discussed earlier, the seal element 20 is a stack of frusto-conical washers 5 22. Referring to Figure 13 there is shown a perspective view of one of the first conical washers 22. Each frusto-conical washer 22 is made from Inconel steel and coated in a layer of silver 35 microns thick. The washer inner edge 44 defines an aperture through which the plug mandrel 18 passes and when the seal is set this inner edge 44 is adapted to sealingly engage the mandrel 18. The outer washer edge 46, 10 when the seal element 20 is energised, is adapted to form a seal with a conduit, each washer 22 in the stack forming an independent seal from every other washer 22. As can be seen from Figure 14, a schematic cut away side view of part of a stack of frusto-conical washers 22 in an uncompressed configuration, between each washer 22 there is a laminate of softer material 48. This laminate 48 is made up of a 15 central layer 50 of PEEK sandwiched between two layers 52 of PTFE. As the stack of washers 22 is energised, by being compressed by relative movement between the housing 14 and the plug mandrel 18, the laminate 48 is squeezed radially inwards, forming a seal with the plug mandrel 18, and radially outwards, forming a seal with the conduit 90. Figure 15 shows a schematic cut away side view of part of a stack of 2 0 frusto-conical washers 22 in a compressed, or set, configuration As can be seen from Figure 15 the laminate of softer material 48 is squeezed beyond the edges of the washers 22, and assists in forming a seal if the conduit 90 is not entirely smooth; the softer material spreading into any voids or inconsistencies in the surface of the conduit 90. 25 It will be noted from Figure 15 that even when fully compressed each washer 22 is not completely flattened. In the uncompressed state the angle of each washer to the horizontal, indicated as angle 0 on Figures 14 and 15, is 8' to the horizontal. In the compressed, or set, configuration angle 0 is 5 '. The retention of a slight angle to the horizontal assists the seal element in recovering back to the uncompressed 30 configuration when the compression force is removed. Referring back to Figure 7, in the leading end 38 of the plug 10 is a reservoir 40. The reservoir 40 is sealed from the surrounding environment and contains a body of air at a pressure of I bar. A reservoir cap 42 is provided which seals the reservoir 40 and is adapted to rupture at a given threshold pressure. The purpose of the 3820582-1 13 reservoir 40 is to reduce pressure on the seal element 20 in the event that a volume of air becomes trapped and pressurised below the plug 10. A volume of air may get trapped if, for example, it is decided to set two plugs 10 in series. Without the reservoir 40, the increased pressure would apply a force on the 5 plug 10 which may affect the integrity of the seal element 20. With the reservoir 40, before any damage can be done to the integrity of the seal, the cap 42 ruptures, with the effect of reducing the overall pressure of the air trapped below the plug 10. Figures 5 to 7 explained the setting of the plug 10 in the conduit 90, the releasing and retrieval of the plug will now be described with reference to Figures I to 10 4 and Figures 8 to 10. The releasing and retrieval of the plug 10 is achieved using conventional wireline techniques The plug 10 is prevented from being removed from the conduit 90 by the locking means 24, particularly because the plug mandrel 18 can not move in the release direction relative to the housing 14. As previously discussed the locking nut 15 26 comprises a first portion 56 and a second portion 58, the first portion 56 comprising six radially moveable sections 60, which together define one half of the threaded connection 27 between the locking nut 26 and the plug mandrel 18. The retaining sleeve 30 prevents radial movement of the locking nut sections 26. Referring to Figure 8, a cut away side view of the plug 10 in the conduit 90 20 showing the retaining sleeve 30 disengaged from the locking nut 26, sufficient force has been applied to the retaining sleeve 30 by a wireline controlled releasing tool (not shown) to overcome the shear screws 32 so the shear screws 32 are no longer securing the retaining sleeve 30 to the locking nut 26, permitting the six moveable sections 60 to move radially outwardly and break the threaded connection 27 between the locking 25 nut 26 and the plug mandrel 18. As the plug mandrel 18 is no longer locked relative to the housing 14, the wireline controlled releasing tool can apply a force to the plug mandrel 18 to move the plug mandrel 18 in the release direction, that is in the direction of arrow "R" on Figure 8. 30 As the plug mandrel 18 moves in the direction of arrow "R", the compression force on the seal element 20 is removed and the seals are permitted to spring back to the uncompressed configuration, releasing the pressure below the seal element 20. Referring to Figure 9, a cut away side view of the plug 10 in the conduit 90 showing the seal element 20 released, the plug mandrel 18 includes a grooved section 3820582-1 14 120 describing a number of grooves 122. The grooves 122 can be seen more clearly on Figure 16, a perspective view of part of the plug mandrel 18. When the seal element 20 is set, the inner edge 44 of each washer 22 engages a non-grooved section 124 of the plug mandrel 18, however as the plug mandrel 18 moves in the release 5 direction the grooved section 122 is translates behind the seal element 20, and a pressure equalising flow path is created around the seal element 20. To ensure the seal element 20 does not re-set, the plug mandrel 18 is also provided with a wickered surface 126 (Figures 9 and 16) which engages with a complementary wickered element 128 (Figure 9), which is secured to the lower 10 housing section 17 by a screw 130. The engagement between the wickered surface 126 and the wickered element 128 is arranged to permit only uni-directional movement, thereby preventing the plug mandrel 18 moving and resetting the seal element 20. The plug mandrel 18 is moved in the direction arrow "R" until the plug mandrel lug 132 engages the wickered element 128, preventing further movement of 15 the plug mandrel 18. With the seal between the plug 10 and the conduit 90 broken, the plug 10 can be safely removed from the conduit 90, because the seal element 20 has been de energised and pressure equalisation has occurred across the seal element 20. The pressure equalisation prevents the possibility of the plug being blown up the conduit 20 90 by pressure trapped below the plug 10. The wireline releasing tool is recovered to surface and a wireline pulling tool (not shown) is sent down to the plug 10 to engage the plug housing 14. Referring to Figure 10, a cut away side view of the plug 10 in the conduit 90 showing the anchoring dogs 34 released. As the input mandrel 18 can not now move 25 relative to the housing 14, the upper housing section 15 moves in the direction of arrow "S" under the action of the wireline pulling tool. The housing ramp 54 moves away from the dogs 34 permitting the dogs 34 to retract into the housing 14 through the housing apertures 36. The plug 10 is now released from the conduit 90 and can be recovered to 30 surface by the wireline pulling tool. A second embodiment of the present invention will now be described with reference to Figures 17-23. Referring firstly to Figure 17, there is shown a perspective view of a plug, generally indicated by reference numeral 510, for sealing a conduit in accordance 3820582-1 15 with a second embodiment of the present invention. The plug 510 comprises a housing 512 having a longitudinal axis 514. The plug 510 further includes a plurality of seal elements 516 for creating a seal between the plug 510 and the conduit (not shown). Within the housing 512 is a seal setting means 518 for setting the plurality 5 of seal elements 516 by rotationally translating the seal setting means 518 with respect to the housing 512 such that the plurality of seal elements 516 are compressed into a sealing engagement with the conduit (not shown). The plug further includes an anchoring system 520 for securing the plug 10 in the conduit (not shown). The anchoring system 20 includes a dog expander ramp (shown and discussed in 10 connection with Figure 18) and a plurality of dogs 522. The anchoring system 520 is set by anchor setting means 524. Rotation of the anchor setting means 524 with respect to the housing 512 translates the anchor setting means 524 with respect to the housing 512 and forces the dogs 522, through the dog expander ramp 528, into engagement with recesses in the conduit (not shown). 15 These and additional elements of the plug 510 can be seen on Figure 18, a sectional view of the plug 510 taken through line A-A on Figure 17. As can be seen from Figure 18, the anchor setting means 524 comprises a dog nut 526, the anchoring system 520 comprises six dogs 522 and the housing 512 further comprises a dog expander ramp 528. The dog nut 526 engages the housing 12 by means of a threaded 20 connection 530. As the dog nut 526 is rotated it translates to the right of Figure 18. This translation acts on the dog expander ramp 528 which also moves to the right. The dog expander ramp 528 includes a leading surface 532 which engages a back surface 534 of the dogs 522. Co-operation between the dog expander ramp leading surface 532 and the dog back surface 534 causes the dogs 522 to move outwards from 25 the plug 510, through apertures 521 in the housing 512, in a direction perpendicular to the longitudinal axis 514. Referring now to Figure 19, there is shown a sectional view through line B-B from Figure 18. This shows that the dog expander ramp 528 is rotationally fixed to the housing 512 by means of a key 536. Therefore as the dog expander ramp 528 30 translates to the right it does not rotate. Referring back to Figure 18, the plug 510 further includes an anchor ratchet 538. The anchor ratchet 538 comprises a set of teeth or serrations (not shown) in the form of a buttress, located on an end surface 544 of the dog nut 524 and three complementary anchor ratchet tangs (not shown on Figure 18) located on a first rotary 3820582-1 16 lock ring 546 pinned to the dog expander ramp 520. The engagement of the tangs and the teeth or serrations allows rotation in one direction but not the other as the tang prevents rotation in the opposite direction because it would lock against the buttress. The first rotary lock ring 546 can be best seen in Figure 20a, a perspective 5 view of the first rotary lock ring 546. The first rotary lock ring 546 comprises three tangs 542 located on, and sitting proud of, an external surface 552 of the first rotary lock ring 546. One of the tangs is also shown in enlarged detail on Figure 20a. The tangs 542 are machined into the first rotary lock ring 546, and are bent outwards such that edge 553 forms a ratchet with the serrated face 544 of dog nut 524. 10 The first rotary lock ring 546 is centred on the longitudinal axis 514 of the plug 10 such that the anchor ratchet 538 is arranged along an arc centred on, and substantially perpendicular to the longitudinal axis 514. Referring back to Figure 18, the plurality of seal elements 516 comprises a stack of fifteen frusto-conical washers 554. Frusto-conical washers 554 are used 15 because a high expansion ratio is achievable by compression of a frusto-conical washer permitting the plug 510 to be run into position within a conduit without building up a significant head of pressure in front of the plug 510. The plug 510 is set by seal setting means 518 which comprises a two-part mandrel 556a,b. The mandrel 556a,b is connected to the housing 512 by means of a threaded connection 20 558. The threaded connection 558 is such that if the seal setting means 518 is rotated it translates to the left of Figure 17, travelling along the threaded connection 558. This motion compresses the frusto-conical washers 554 increasing the radius 560 defined by the frusto-conical washers 554 from the longitudinal axis 514. As they expand, the frusto-conical washers 554 engage the wall of a conduit (not shown) and 25 form a seal with the conduit. Over compression of the frusto-conical washers 554 is prevented by stop 562 engaging with housing no-go 564. The plug 510 further includes a seal ratchet 580. The seal ratchet 580 comprises a set of teeth (not shown) located on an external surface 582 of the mandrel 30 556 and six complementary seal ratchet tangs (not shown on Figure 18) located on a second rotary lock ring 584. The second rotary lock ring 584 can be best seen in Figure 20b, a plan view of the second rotary lock ring 584. The second rotary lock ring 584 is secured to the housing no-go 564 by lugs 586. The second rotary lock ring 3820582-1 17 584 comprises six tangs 588 located on, and sitting proud of, an internal surface 590 of the second rotary lock ring 584. The second rotary lock ring 584 is centred on the longitudinal axis 514 of the plug 510 such that the seal ratchet 580 is arranged along an are centred on, and 5 substantially perpendicular to the longitudinal axis 514. The setting of the plug 510 is a two stage process because the plug 510 is arranged such that rotation in one direction (here after referred to as direction X) will drive the dog nut 526 and set the dogs 522 in a conduit recess, and rotation in the opposite direction (hereafter referred to as direction Y) will drive the mandrel 556 and 10 set the sealing element 516. Referring now to Figure 21, there is shown a perspective view of a plug running adapter generally indicated by reference numeral 610 for setting the plug 510 in a conduit in accordance with a second embodiment of the present invention. The plug running adapter includes a housing 612, and a tubular member 614 extending 15 from the housing 612. The tubular member 614 has a longitudinal axis 616, an outer surface 618 and an inner surface 620. The outer surface 618 is adapted to engage the anchor setting means 524 of the plug 510 and the inner surface 620 is adapted to engage the seal setting means 518 of the plug 510. Located on the inner surface 620 of the tubular member 614 are first 20 engagement clement 622 and located on the outer surface 618 of the tubular member 614 are second engagement elements 624. The first and second engagement elements 622,624 can be best seen on Figure 22, a sectional view taken through line C-C of Figure 21. Each engagement element 622,624 is pivoted at one end about a pivot 626- The first engagement element 622 are biased to sit proud of the internal 25 surface 620 of the tubular member 614 and the second engagement elements 624 are biased to sit proud of the outer surface 618 of the tubular member 614, as shown in Figure 22. Associated with each of the first engagement elements 622 are first tubular member recesses 628 and associated with each of the second engagement elements 624 are second tubular member recesses 630. 30 Referring to both Figures 17 and 22 the anchor setting means 524 in the form of dog nut 526 have a number of second complimentary notches 640 in the internal surface 642 of the dog nut 526. When the rotation of the running adapter 612 is in the direction X, the second engagement elements 624 engage the inner surface 644 of the second complimentary notches 640 thereby driving the dog nut 528, and setting 3820582-1 18 the dogs 522. When the rotation of the running adapter is in direction Y, the inner surface 642 of the dog nut 528 depresses the second engagement 630 elements 624 into the second tubular member recesses 630. Continuing to refer to Figures 17 and 22, the first engagement elements 622 5 are adapted to engage with first complimentary notches 632 on the outer surface of the mandrel 556. The complimentary notches 632 are separated by fingers 634. The pivotal mounting of the first engagement elements 622 means that when the running adapter 610 is driven in direction Y, the first engagement elements 622 engage with the inner surface 636 of the first complimentary notches 632 thereby rotating the 10 mandrel 556, and setting the seal element 516. When the direction of the running adapter is reversed, to direction X, the upper surface 638 of the fingers 634 press the first engagement elements 622 into the first tubular member recesses 628 such that there is no driving engagement between the running adapter 610 and the mandrel 556. Referring now to Figure 23, comprising Figures 23a to 7d, there is shown a 15 schematic of the plug 510 of Figure 17 being set in a wellbore 700. The plug 510 is shown in Figure 23a attached to the running adapter 610, which in turn is suspended from a wireline cable 710. The running adapter 610 includes a latch (not shown) which engages a recess 557 (Figure 18) in the inner surface of the mandrel 556. In Figure 23a, the plug/running adapter 510,610 is being 20 run into the wellbore 700. When the plug 510 is in the correct position, shown in Figure 23b the dogs 522 are set in recesses 712. The dogs are set, as described above, by rotating the tubular member 614 (Figure 21) of the running adapter 610 in a first direction. This rotation drives the dog nut 526 (Figure 18) towards the dogs 522, which are moved 25 into the position shown in Figure 23b by the action of the dog expander ramp 528 (Figure 18). Once the dogs 522 have been set in the recesses 712, and the plug 510 is correctly located in the wellbore 700, the running adapter tubular member 614 is rotated in a second direction, which is opposite to the first direction. This rotation 30 drives the two-part mandrel 556a,556b, which in turn compresses the frusto-conical washers 714 into a sealing engagement with the wall 716 of the wellbore 700, as shown in Figure 23c. The plug 510 is now set in the wellbore 700. 3820582-1 19 Finally the running adapter 610 is disconnected by shearing the running adapter latch (not shown) from the plug recess 557 (Figure 18). The adapter 610 is then withdrawn to surface. Various modifications and improvements may be made to the embodiments 5 hereinbefore described without departing from the scope of the invention. For example, it will be understood that any suitable form of seal element may be used or slips may be used instead of the dogs described. For example, multiple metal seals could be used or, alternatively, a combination of metal and plastic seals where seal bore damage prevents an all metal seal arrangement from testing. Additionally, with 10 regard to the first described embodiment, although a two trip releasing and recovery of the plug has been described, a single trip wireline tool could be used or the running adapter could be modified to retrieve the plug as well as set the plug. Those of skill in the art will also recognise that the above described embodiment of the invention provides a plug in which backlash is substantially 15 reduced. The use of a rotary lock mechanism substantially prevents any movement within the plug and is unaffected by vibration which can occur at the wellhead. Furthermore, from a simple rotational input the running adapter produces both rotational and axial force to set and seal the plug in the conduit. Because the running adapter delivers all the force required during setting and because the seal element is a 20 smaller diameter than the diameter of the conduit at the point of sealing, there is no requirement for jarring and no damage is done to the conduit bore. 3820582-1

Claims (15)

1. A running adapter for setting a plug in a conduit which extends downhole, the running adapter being releasably connectable to the plug and the running adapter comprising: an input mandrel; an output mandrel; an adapter casing; and a locking sleeve, the running adapter being arranged such that rotation of the input mandrel causes axial movement of the output mandrel relative to the adapter casing, and causes rotational movement of the locking sleeve relative to the adapter casing.

2. The running adapter of claim 1, wherein the input mandrel is adapted to be connected to a rotary drive.

3. The running adapter of claim 1 or 2, wherein the adapter casing is adapted to engage a plug first body section.

4. The running adapter of any of claims 1 to 3, wherein the output mandrel is adapted to engage a plug second body section.

5. The running adapter of any of claims 1 to 4, wherein the locking sleeve is adapted to engage a plug seal and/or anchor locking means.

6. The running adapter of any of claims 1 to 5, wherein the locking sleeve is adapted to selectively engage the input mandrel.

7. The running adapter of any of claims 1 to 6, wherein the locking sleeve is adapted to selectively rotate with the input mandrel.

8. The running adapter of any of claims 1 to 7, wherein the running adapter further comprises a locking sleeve clutch to disengage the locking sleeve from the input mandrel. 2347054v1 21

9. The running adapter of any of claims 1 to 8, wherein the adapter casing is connected to the input mandrel by a threaded connection.

10. The running adapter of any of claims 1 to 9, wherein the output mandrel is axially fixed to the input mandrel.

11. The running adapter of any of claims 1 to 10, wherein the output mandrel is rotationally independent of the input mandrel.

12. The running adapter of any of claims 1 to 11, wherein a bearing interface is provided between the input mandrel and the output mandrel.

13. The running adapter of any of claims 1 to 12, wherein the output mandrel includes a bearing surface.

14. The running adapter of any of claims 1 to 13, further comprising a latch, the latch being adapted to be located, in use, between the output mandrel and a plug second body section.

15. A running adapter substantially as hereinbefore described with reference to the accompanying drawings. 2347054v1