Description

Field of the Invention

The present invention relates to well plugs and barriers. These may be for both oil and gas production and wireline applications, but may also be usable in other borehole applications, such as fracking, water wells, etc.

Background to the Invention

Well plugs and barriers are used predominantly in downhole oil and gas applications. They prevent fluid flow out of or into the well. They may be used in pairs as a primary and secondary well barrier or may be used individually.

Well barriers are typically placed into lined boreholes (either production or wireline) and a locking mechanism activated to maintain the well barrier in place. In prior art solutions, this is most commonly achieved by the use of slips which are hinged wedges that pivot out into contact with the borehole.

The use of slips is disadvantageous as they often damage the liner because of the point loading. This is especially true where the liner is provided with a plastic coating, but may also be an issue in metal liners, such as titanium liners. Summary of the Invention

According to a first aspect of the present invention there is provided a well barrier comprising a body, the body having one or more gripping pads provided within it, the one or more gripping pads being mounted within one or more gripping pad apertures, the one or more gripping pads being mounted on gripping pad mounts, the one or more gripping pads being extendable from a retracted position, wherein an outer gripping surface of the one or more pads is in line with or beneath an outer surface of the body surrounding the one or more gripping pad apertures, to an extended position where the outer gripping surface is raised above the outer surface of the body surrounding the one or more gripping pad apertures.

The present invention provides a well barrier which may be deployed without the need to provide slips which may damage the wellbore lining.

The body may be generally cylindrical in form and the one or more gripping pads may extend radially outwardly from a central axis of the well barrier.

The one or more gripping pads may be provided in one or more arrays.

There may be two or more gripping pads per array.

There may be four or more gripping pads per array.

There may be two or more arrays per well barrier. The two or more arrays may be provided at an angle to one another measured around the central axis.

This may provide an overlap of gripping pads along the length of the body and as measured radially around the body. This may mitigate any slippage occurring and may improve gripping function.

The outer gripping surface(s) of the one or more gripping pads may be provided with a treatment to increase the frictional resistance of the surface.

This increase in frictional resistance may be provided by roughening, knurling, and/or coating the surface.

The body may contain a locking actuation mechanism.

The locking actuation mechanism may comprise a locking ring mounted within the body and abutting one or more latches, the locking ring being movable longitudinally within the body and being able to urge a split ring from an initial or retracted position to a second or locked position.

The retracted and locked positions of the split ring may accord with the retracted and extended positions of the one or more gripping pads.

The locking ring may be generally cylindrical with one or more flat faces formed on an outer surface of the locking ring.

The locking ring may be a split ring. An interior bore of the locking ring may be provided with a ratchet thread.

The ratchet thread may comprise one or more raised lips provided around the interior bore of the locking ring.

The interior bore of the locking ring may be provided with one or more latch slots running longitudinally.

The one or more latches may be seated within the one or more latch slots.

The one or more latches may be elongate bars.

The one or more latches may have a first end and a second end.

The first end may have a first end raised portion.

The second end may have a second end raised portion.

The first and/or second end raised portions may function as cam surfaces.

The first and/or second end raised portions may function to raise and/or lower the split ring into and out of engagement.

There may be provided a central slot engaging tab provided between the first end raised portion and the second end raised portion.

According to a second aspect of the present invention there is provided a well barrier comprising a body, the body having a locking actuation mechanism comprising a locking ring mounted within the body and abutting one or more latches, the locking ring being movable longitudinally within the body and being able to urge a split ring from an initial or retracted position to a second or locked position.

The body may have one or more gripping pads provided within it, the one or more gripping pads being mounted within one or more gripping pad apertures, the one or more gripping pads being mounted on gripping pad mounts, the one or more gripping pads being extendable from a retracted position, wherein an outer gripping surface of the one or more pads is in line with or beneath an outer surface of the body surrounding the one or more gripping pad apertures, to an extended position where the outer gripping surface is raised above the outer surface of the body surrounding the one or more gripping pad apertures.

The body may be generally cylindrical in form and the one or more gripping pads may extend radially outwardly from a central axis of the well barrier.

The one or more gripping pads may be provided in one or more arrays.

There may be two or more gripping pads per array.

There may be four or more gripping pads per array.

There may be two or more arrays per well barrier.

The two or more arrays may be provided at an angle to one another measured around the central axis.

This may provide an overlap of gripping pads along the length of the body and as measured radially around the body. This may mitigate any slippage occurring and may improve gripping function.

The outer gripping surface(s) of the one or more gripping pads may be provided with a treatment to increase the frictional resistance of the surface.

This increase in frictional resistance may be provided by roughening, knurling, and/or coating the surface.

The retracted and locked positions of the split ring may accord with the retracted and extended positions of the one or more gripping pads.

The locking ring may be generally cylindrical with one or more flat faces formed on an outer surface of the locking ring.

The locking ring may be a split ring.

An interior bore of the locking ring may be provided with a ratchet thread.

The ratchet thread may comprise one or more raised lips provided around the interior bore of the locking ring.

The interior bore of the locking ring may be provided with one or more latch slots running longitudinally. The one or more latches may be seated within the one or more latch slots.

The one or more latches may be elongate bars.

The one or more latches may have a first end and a second end.

The first end may have a first end raised portion.

The second end may have a second end raised portion.

The first and/or second end raised portions may function as cam surfaces.

The first and/or second end raised portions may function to raise and/or lower the split ring into and out of engagement.

There may be provided a central slot engaging tab provided between the first end raised portion and the second end raised portion.

Brief of the

Embodiments of the present invention will now be described, by way of example only, with reference to the following drawings, in which:

Fig. 1 is a perspective view of a first embodiment well barrier according to the present invention;

Fig. 2 is a sectional elevation of the well barrier of Fig. 1 ; Fig. 3 is a perspective view of a locking ring of the well barrier of Fig. 1 ;

Fig. 4 is a sectional elevation of the locking ring of Fig. 3;

Fig. 5 is a perspective view of a latch of the of the well barrier of

Fig. 1 ;

Fig. 6 is a side elevation of the latch of Fig. 5;

Fig. 7 is a part-sectional perspective view of the locking ring within the well barrier of Fig. 1 ;

Fig. 8 is a detail perspective view of the gripping pad arrays of the well barrier of Fig. 1 in a retracted state;

Fig. 9 is a sectional side elevation of the gripping pad arrays of the well barrier of Fig. 1 in a retracted state;

Fig. 10 is a detail perspective view of the gripping pad arrays of the well barrier of Fig. 1 in an extended state;

Fig. 11 is a sectional side elevation of the gripping pad arrays of the well barrier of Fig. 1 in an extended state;

Fig. 12 is a perspective view of a gripping pad of the well barrier of Fig. 1 ; Fig. 13 is an end elevation of the gripping pad of Fig. 12;

Fig. 14 is a perspective view of a gripping pad mount of the well barrier of Fig. 1 ;

Fig. 15 is a plan view of the gripping pad mount of Fig. 12;

Fig. 16 is a perspective detail view of the locking ring and latch assembly of the well barrier of Fig. 1 ;

Fig. 17 is an exploded perspective view of the gripping pad array assembly of the well barrier of Fig. 1 ;

Fig. 18 is a perspective view of a second embodiment well barrier according to the present invention.

Referring to the drawings and initially to Fig. 1 , a well barrier according to the present invention is depicted, generally referred to as 10. The well barrier 10 comprises an outer body 12. The outer body 12 has a generally elongate cylindrical form and extends from a leading edge or point 14 to a trailing edge or rear 16.

In general, the well barrier comprises a body 12, the body 12 having one or more gripping pads 18 provided within it, the one or more gripping pads 18 being mounted within one or more gripping pad apertures 20, the one or more gripping pads 18 being mounted on gripping pad mounts 22, the one or more gripping pads 18 being extendable from a retracted position, wherein an outer gripping surface 24 of the one or more gripping pads 18 is in line with or beneath an outer surface of the body 12 surrounding the one or more gripping pad apertures 20, to an extended position where the outer gripping surface 24 is raised above the outer surface of the body 12 surrounding the one or more gripping pad apertures 24.

The body 12 in the present embodiment is comprised of a plurality of modular sections, in the present embodiment there are five such modular sections. It will be understood that such modular sections may be added to or decreased to produce multiple different alternative embodiments.

These modular sections will now be described as they occur from the leading edge 14 to the trailing edge 16. A nose cap 26 is provided first adjacent to and forming the leading edge 12. The nose cap 26 is an elongate cylindrical body 28 with a chamfered/frusto-conical formation 30 provided adjacent the leading edge 12. The chamfered/frusto-conical formation 30 assists in locating the barrier 10 into a wellbore (not shown). A central leading edge bore 32 is provided adjacent the leading edge 12 at the front of the nose cap 26. The central leading edge bore 32 may be used to suspend gauges or the like from the leading edge 12 of the barrier 10.

A first gripping pad section 34 is provided adjacent to and attached to the nose cap 26. A first gripping pad array 36 is provided on the first gripping pad section 34. The first gripping pad array 36 comprises a first gripping pad array chassis 38 surrounded by a cylindrical first gripping pad array sleeve 40. The cylindrical first gripping pad array sleeve 40 is provided with four gripping pad apertures 18 around its external surface. Four gripping pad mounts 22 are slidably mounted within the chassis 38 and may extend radially outwardly from a central axis X-X of the well barrier 10 from a retracted position (shown in Figs 8 and 9) to an extended position (shown in Figs 10 and 11). In the retracted position, the gripping surfaces 24 of the pads 18 are substantially flush with the outer surface of the sleeve 40 such that a largely smooth exterior surface to the sleeve 40 is provided when deploying the barrier 10. In the extended position, the gripping pad mounts 22 are urged radially outwardly from the central axis X-X, such that the gripping surfaces 24 of the pads 18 are displaced beyond the exterior surface of the sleeve 40 and into contact with a lined bore in which the barrier is being deployed.

The chassis 38 comprises a central cylindrical portion 42 with a first shoulder flange cap 44 provided at an end located towards the leading edge 14 and a second shoulder flange cap 46 provided towards the trailing edge 16. The first and second flange caps 44, 46 are largely identical. The flange caps 44, 46 are generally cylindrical. Four chamfers 48, 50 are formed on the innermost side of each cap 44, 46, such that the chamfers 48, 50 face each other across the central cylindrical portion 42. Four slots 52, 54 are formed longitudinally (i.e. parallel to the axis X-X) in the centre of each chamfers 48, 50. Four screw holes 56, 58 are formed on the caps on the opposite edge from the flange/slot formation.

Two mounting bosses 60, 62 are provided on the central cylindrical portion 42. The mounting bosses 60, 62 are a short section of increased thickness. Four corresponding screw bores 64, 66 are provided on the mounting bosses 60, 62. Shear screws 68 attach the flange caps 44, 46 to the mounting bosses 60, 62.

Four gripping pad mounts 22 are provided around the chassis 38 spanning the central cylindrical portion 42 between the flange caps 44, 46.

The gripping pad mounts 22 comprise a central beam 70 with mounting lugs 72, 74 provide at either end of the central beam 70. A mounting plinth 76 is formed on a side edge of the central beam 70. The mounting plinth 76 has a T-profile when viewed along the length of the mounts 22. The lugs 72, 74 are located within the flange caps 44, 46. Portions of the central beam 70 located adjacent each lug 72, 74 extend through the slots 52, 54. This locates the gripping pad mounts 22 adjacent the gripping pad apertures 20.

The gripping pads 18 have a corresponding T-shaped internal slot 78 allowing the gripping pads 18 to be mounted on the gripping pad mounts 22. The gripping pads 18 have a generally oblong shape and the gripping surface 24 has a slight curve which generally matches that of the internal diameter of a well liner (not shown) in which the barrier 10 is to be deployed. The edge 80 of the gripping surface 24 is filleted. The four corners 82 of the gripping pads 18 are also filleted. The bottom surface 84 (opposite the gripping surface 24) is formed with a concave depression 86 adjacent the T-shaped internal slot 78. Chamfers 88 are provided on both of the short ends 90 the chamfers 88 being slightly less in depth than the margin of the T-shaped internal slot 78. The chamfers 88 of the gripping pads 18 match the chamfers 48, 50 of the first and second flange caps 44, 46. As the chamfers 48, 50 are compressed towards one another, they meet the chamfers 88 and urge the gripping pads 18 outwardly from the central axis X-X and into contact with a well liner. The outer gripping surface 24 of the gripping pads 18 may be provided with a treatment to increase the frictional resistance of the surface 24. This increase in frictional resistance may be provided by roughening, knurling, and/or coating the surface. In the present embodiment, the gripping surfaces 24 have been roughened to provide that increase in frictional resistance.

A second gripping pad section 90 is provided adjacent to and attached to the first gripping pad section 34. The second gripping pad section 90 is identical to the first gripping pad section 34 and does not need to be described further. The second gripping pad section 90 is attached to the first gripping pad section 34 at an angle of 45°. As can be seen from the Figs, this means that the gaps between the gripping pads 18 on the first gripping pad section 34 are effectively covered upstream by the position of the gripping pads 18 on the second gripping pad section 90; there is an overlap when viewed longitudinally along the barrier 10. It will be understood that further gripping pad sections may be added to both improve grip and increase contact area/footprint of the gripping pads 18 on the well liner (not shown). This may also decrease contact pressure.

An actuator section 92 is provided adjacent to and attached to the second gripping pad section 90. A locking actuation mechanism 94 is housed within the actuator section 92.

The locking actuation mechanism 94 comprises a locking ring 96 mounted within the actuator section 92 and abutting one or more latches 98, the locking ring 96 being movable longitudinally within the actuator section 92 of the body 12 and being able to urge a split ring 100 from an initial or retracted position to a second or locked position.

The retracted and locked positions of the split ring 100 corresponds with the retracted and extended positions of the one or more gripping pads 18.

The locking ring 96 is generally cylindrical with one or more flat faces 102 formed on an outer surface of the locking ring 96. The flat faces 102 in the present embodiment are machined into the exterior surface of the locking ring 96.

A ratchet thread 104 is provided on the interior bore 106 of the locking ring 96. The ratchet thread 104 comprises one or more raised lips provided around the interior bore 106 of the locking ring 96.

Three latch slots 108 are provided on the interior bore 106 of the locking ring 96 running longitudinally i.e. parallel to axis X-X and perpendicular to the ratchet thread 104. The three latches 98 are seated within latch slots 108.

The latches 98 are generally elongate bars. The latches 98 have a first end 110 and a second end 112. The first end 110 has a first end raised portion 114. The first end raised portion 114 is filleted to form a substantially rounded end. The second end 112 has a second end raised portion 116. A central raised portion 113 is provided which has a slight taper which increases between the first end 110 and second end 112. The central raised portion 113 is situated within the locking ring 96. A seal 115 is provided between the second end raised portion 116 and the central raised portion 113 which abuts the locking ring 96 and an exterior body 97 of the actuator section 92.

The first end raised portion 114 functions as a form of cam surface as will subsequently be described.

A central locking mandrel 118 is provided around which the components of the locking mechanism 94. A corresponding mandrel ratchet thread 120 is provided on the central locking mandrel 118. The mandrel ratchet thread 120 corresponds and cooperates with the locking ring ratchet thread 104. Although formed as threads in the present invention (i.e. helical windings) the ratchets may be formed as a succession of unconnected raised lips as an alternative. Three latch grooves 123 are formed longitudinally along the central locking mandrel 118. These receive the latches 98 and allow them to slide along the mandrel 118.

A locking ring socket portion 115 is provided at the second end of the actuator section providing a close but sliding fit between it and the locking ring 96. The locking ring socket portion 115 has an internal tapered surface 117 which expands from the narrowest section at a throat of the locking ring socket portion 115 adjacent an end cap 150 towards the first end 14 of the barrier 10.

As the barrier 10 is set, the locking ring 96 is urged from the second end 16 towards the first end 14. The locking ring 96 traverses the central locking mandrel 118. The locking ring ratchet thread 104 interacts with the mandrel ratchet thread 118 and causes the locking ring 96 to expand radially (by virtue of it being a split ring) to enable the ratchets 104, 120 to pass over one another. There may be an audible “clicking” as the locking ring 96 successfully engages, expands, and disengages the mandrel ratchet thread 118 as it moves along the mandrel 118. The split ring 100 is in turn urged towards the first end 14 under the action of the moving locking ring 96. A connecting sleeve 124 is provided between the split ring 100 and the gripping arrays. A sleeve shoulder 126 is provided on the edge adjacent the locking mechanism 94. The sleeve shoulder 126 is filleted and the split ring 100, having a corresponding fillet at the adjacent side, abuts and then urges the sleeve shoulder 126 towards the first end 14 of the barrier 10, as the locking ring 96 travels along the mandrel 118. A second end 128 of the connecting sleeve 122 has a slightly flared initial portion 130 with a diameter sufficient to receive the first end raised portions 114 of the latches 98.

A first end 132 of the connecting sleeve 122 is attached to the flange cap 46 of the second gripping array 90. Thus, as the connecting sleeve 122 is urged towards the first end 14, the flange cap 46 abuts the gripping pads 18 and urges them outwards into engagement with the well liner (not shown).

A further connecting sleeve 134 connects the first flange cap 44 of the second gripping array 90 to the first flange cap 46 of the first gripping array 34 and causes similar outward travel of the gripping pads 18 of the first array 34. Similar connections may be made in the event of embodiments incorporating further gripping pad arrays.

A tail section 150 is attached to the actuator section 92. The tail section 150 comprises a cylindrical body 152 with a first flared end 154 and a second flared end 156. The first flared end 154 attaches to the actuator section 92 and the second flared end is effectively the second end 16 of the barrier 10. Fillets 158, 160 are provided between the cylindrical body 152 and the flared ends 154, 156. Prior art barriers typically have an actuating mechanism which activates the slips into and out of engagement from a first, unlocked position, to a second locked position. Once locked, they do not readily become unlocked without full removal of the barrier.

In contrast, the present invention also allows unlocking of the mechanism whilst in situ.

Shear screws 162 attach the tail section 150 to the actuator section 92.

These may be sheared to enable the mechanism to be reset. Once sheared, the locking ring 96 is free to expand because the locking ring socket portion 115 is free to expand such that the ratchets are no longer in engagement and is therefore able to move back towards the second end 16. The second raised ends 114 of the latches 98 act as a cam surface or hammer mechanism which expand the split ring 100 out of engagement with the connecting sleeve 122 enabling the gripping pads 18 of the individual arrays to retract within the body 12.

A second embodiment well barrier generally referred to as 200 is depicted in Fig. 18. The second embodiment well barrier 200 is similar in construction and function to the first embodiment and employs a numbering scheme similar to the first embodiment albeit prefixed with a “2” or a “3” as the context requires, such that the body is numbered 212 and the tail piece is numbered 350.

The major difference is that the first and second gripping pad arrays are separated by an elongate spacer 380 to provide a greater distance between the two arrays. This may improve stability of the well barrier given the greater distance between the two loading points.