Abstract
An apparatus (10) includes a traction member in the form of a roller (24) configured for mounting on a body (12) so as to permit rotation of the roller (24) relative to the body (12). The roller (24) is mountable on the body (12) so as to define a skew angle relative to a longitudinal axis (26) of the body (12). In use, the roller (24) engages a wall of a borehole or bore-lining tubular and the roller (24) urges the apparatus (10) along the wall of the borehole or bore-lining tubular on rotation of the as the roller (24) rotates on the body (12).
Claims
1. An apparatus for location in a borehole, the apparatus comprising: a body; a traction member comprising a sleeve configured for location around the body, the traction member rotatably mountable on the body so that the traction member rotates around the body, wherein the traction member is mountable on the body so as to define a skew angle relative to a longitudinal axis of the body and is configured to engage a wall of a borehole or bore-lining tubular to urge the apparatus along the wall of the borehole or bore-lining tubular on rotation of the traction member relative to the body; and a fluid lubricated bearing between the traction member and the body wherein at least a part of the fluid lubricated bearing is formed on the traction member, wherein at least part of the traction member comprises, is formed with, or receives an elastomeric or polymer material, the inner surface of the elastomeric or polymer material provided with flutes and pads to create the fluid lubricated bearing.
2. The apparatus of claim 1, wherein the traction member is mountable on the body so that the traction member is offset from a central longitudinal axis of the body.
3. The apparatus of claim 1, wherein the traction member is rotatably mountable on the body so that the traction member transmits force to the body.
4. The apparatus of claim 1, wherein the traction member is configured to engage with at least one other traction member.
5. The apparatus of claim 1, wherein the traction member comprises a radially extending rib or blade or other upset diameter portion.
6. The apparatus of claim 1, wherein the traction member is formed to define the skew angle.
7. The apparatus of claim 1, wherein the body defines the skew angle.
8. The apparatus of claim 1, wherein the angle of skew of the traction member is selected to urge the apparatus along the wall of the borehole at a selected rate.
9. The apparatus of claim 1, wherein a direction of skew angle of the traction member is selected to urge the apparatus in a selected direction along the wall of the borehole.
10. The apparatus of claim 1, wherein the apparatus is configured so as to have a first, passive configuration and a second, active, configuration in which the traction member urges the apparatus along the inner wall of the borehole or bore-lining tubular.
11. The apparatus of claim 1, wherein the body comprises a connector for coupling the body to a tubular string.
12. The apparatus of claim 1, comprising a plurality of the traction members, wherein at least one of: a plurality of the traction members are configured for location on the body in abutting relation to each other; and a plurality of the traction members are longitudinally spaced along the length of the body.
13. An assembly comprising: a borehole tubular; and at least one apparatus according to claim 1.
14. The assembly of claim 13, wherein the assembly comprises a downhole drive and rotation of the body is effected at least partly by the downhole drive.
15. The assembly of claim 14, wherein at least one of the apparatus' is arranged at selected downhole locations, so as to provide a traction force at a selected location of the borehole.
16. The assembly of claim 13, wherein one or more apparatus is provided adjacent a distal leading end of the assembly.
17. The assembly of claim 13, wherein the assembly is configured to provide increased thrust in a selected direction and/or provide different amounts of thrust at different points along the length of the assembly.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) These and other aspects of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:
(2) FIG. 1 shows an isometric perspective view of an apparatus according to an embodiment of the present invention;
(3) FIG. 2 shows an enlarged view of the highlighted part of FIG. 1;
(4) FIG. 3 shows an isometric perspective view of the apparatus shown in FIGS. 1 and 2, with traction members removed and showing the offset and skewed journals;
(5) FIG. 4 shows an enlarged perspective view of the highlighted part of FIG. 3;
(6) FIG. 5 shows an enlarged side elevation view of the highlighted part of FIG. 3;
(7) FIG. 6 shows an isometric perspective view of a traction member;
(8) FIG. 7 shows an end view of the traction member shown in FIG. 6;
(9) FIG. 8 shows a ghosted isometric perspective view of the traction member shown in FIGS. 6 and 7;
(10) FIG. 9 shows an enlarged view of the highlighted part of FIG. 8;
(11) FIG. 10 shows an end view of the traction member of FIGS. 8 and 9;
(12) FIG. 11 shows a sectional view of the traction member shown in FIGS. 6 to 10;
(13) FIG. 12 shows a perspective view of an apparatus according an alternative embodiment of the present invention;
(14) FIG. 13 shows a perspective view of an apparatus according to an another embodiment of the present invention;
(15) FIG. 14 shows an end view of the apparatus shown in FIG. 13;
(16) FIG. 15 shows an end view of the apparatus shown in FIGS. 13 and 14, shown within a section of casing;
(17) FIG. 16 shows a partial cut-away view of the apparatus shown in FIGS. 13, 14 and 15;
(18) FIG. 17 shows a perspective view of an apparatus according to an another embodiment of the present invention;
(19) FIG. 18 shows a side view of the apparatus shown in FIG. 17;
(20) FIG. 19 shows a side view of the apparatus shown in FIGS. 17 and 18, with traction members removed;
(21) FIG. 20 shows a partial cut-away view of the apparatus shown in FIGS. 17, 18 and 19;
(22) FIG. 21 is a longitudinal section view of an apparatus according to another embodiment of the present invention;
(23) FIG. 22 is a perspective view of the apparatus of FIG. 21, showing the main body, collet sleeve and activation dart assemblies separately;
(24) FIGS. 23-25 are diagrammatic views showing the mechanism of the present embodiment;
(25) FIG. 26 is an isometric view of an apparatus according to another embodiment of the present invention;
(26) FIG. 27 is a plan view of the apparatus shown in FIG. 26;
(27) FIG. 28 is a longitudinal sectional view of the apparatus shown in FIGS. 26 and 27 along section A-A;
(28) FIG. 29 is an enlarged perspective view of a roller assembly according to the present invention;
(29) FIG. 30 is a plan view of the roller assembly of FIG. 29;
(30) FIG. 31 shows an exploded view of part of the roller assembly shown in FIGS. 29 and 30;
(31) FIG. 32 shows an exploded view of part of a roller assembly and body showing an alternative construction; and
(32) FIG. 33 shows a longitudinal section view of a ball retent sleeve and activation dart according to an alternative embodiment of the present invention;
(33) FIG. 34 shows an assembly according to an embodiment of the present invention;
(34) FIG. 35 shows an assembly according to another embodiment of the present invention;
(35) FIG. 36 shows an assembly according to another embodiment of the present invention;
(36) FIG. 37 shows an assembly according to another embodiment of the present invention; and
(37) FIG. 38 shows an assembly according to another embodiment of the present invention.
DETAILED DESCRIPTION OF THE DRAWINGS
(38) Referring first to FIGS. 1 and 2 of the drawings, there is shown an apparatus 10 according to an embodiment of the present invention. In the embodiment shown, the apparatus 10 takes the form of a centraliser device or tool and the apparatus 10 forms an integral part of a string of rotational tubulars, such as a drilling or workover string S, for use in a borehole.
(39) In use, the apparatus 10 provides thrust and a transport mechanism for urging the apparatus 10 and connected string S through the borehole. The apparatus 10 additionally provides centralisation of the string S when run and rotated through the borehole, torque reduction and prevents wear to the string S.
(40) As shown in FIG. 1, the apparatus 10 comprises a shaft or mandrel 12. A threaded pin connector 14 is provided at a first end 16 of the mandrel 12 and a threaded box connector 18 is provided at a second end 20 of the mandrel 12. The threaded pin connector 14 and threaded box connector facilitate connection between the ends 16, 20 of the mandrel 12 and the string S. A central throughbore 22 is provided in the mandrel 12 and, in use, the throughbore facilitates the flow of fluid through the apparatus 10 and through the string S.
(41) One or more traction members in the form of rollers 24 are mounted on the mandrel 12. In the embodiment shown in FIGS. 1 and 2, three rollers 24 are provided in abutting relationship on the mandrel 12. The rollers 24 are mounted in such a way as to provide both offset and skew or angle with respect to a central longitudinal axis 26 of the mandrel 12. As can be seen from the figures, the rollers 24 have a bladed configuration and in the embodiment shown the rollers 24 comprises spirally arranged blades 28. In use, the blades 28 provide stabilisation against the inner wall of the borehole or casing whilst maintaining clearance and a flow area 30 between the blades 28 which allows for the flow of return fluids up the annular space between the mandrel 12 and the borehole or casing internal diameter.
(42) Referring in particular to FIG. 2, it can be seen that some of the rollers 24 are provided with a key 32 and a slot 34 at respective ends of the blades 28 in order to maintain alignment of the blades 28 relative to each other.
(43) FIGS. 3, 4 and 5 of the drawings show the apparatus 10 with rollers 24 removed. As shown, a number of offset and skewed journals 36 are machined or otherwise formed in the outer circumferential surface of the mandrel 12, the journals 36 permitting the rollers 24 to be rotationally mounted to the mandrel 12. As can be seen most clearly in FIG. 5, the journals 36 are machined so as to provide an offset and skew with respect to the mandrel axis 26. The provision of offset and skewed rollers 24 introduces a longitudinal force component to the interaction between each roller 24 and the wall of the borehole or bore-lining tubular which acts to urge the apparatus 10 along the borehole or bore-lining tubular. In use, the rollers 24 roll in a helical path rather than a circumferential path around the inside of the borehole or bore-lining tubular wall. This rolling helical path has the effect of transporting the apparatus 10 and the connected string S along the wall of the borehole or bore-lining tubular.
(44) In the embodiment shown, three journals 36 are provided and are arranged at 120 degree radial spacing about the axis 26 of the mandrel 12 such that the rollers 24 mounted on the journals 36 will make three point contact on the internal diameter of the borehole or casing in which they are run. However, it will be recognised that the number of journals, their offset and skew or angle and their angular displacement about the axis 26 may be varied. Also, while the embodiment shown involves machining the journals 36 into the mandrel 12, the journals 36 may alternatively be provided as separate components or with offset and skew or angle incorporated into them.
(45) Referring now to FIGS. 6 and 7 of the drawings, there are shown perspective and end views respectively of a roller 24 according to an embodiment of the invention. In the embodiment shown, the roller 24 is manufactured from a reinforced polymer or elastomeric material such as urethane or nitrile rubber (HNBR).
(46) As described above, and as shown in FIGS. 6 and 7, the roller 24 is provided with a number of radially extending blades 28 which, in use, engage the wall of the borehole or bore-lining tubular and urge the apparatus 10 through the borehole or bore-lining tubular. The key 32 and slot 34 are also shown, these maintaining blade alignment when two or more rollers 24 are mounted on the mandrel 12.
(47) As shown most clearly in FIG. 6, the inner surface 38 of the polymer or elastomeric material of the roller 24 is provided with flutes 40 and pads 42 to create a fluid lubricated bearing similar to a marine cutlass bearing. The pads 42 are sized to make a clearance running fit on the journals 36 on the mandrel 12. The flutes 40 allow free passage of fluid to cool and lubricate the radial bearing thus formed.
(48) On the face of the roller 24, spiralled or angled grooves 44 (see FIG. 7) are formed in the polymer or elastomeric material to encourage fluid to enter the radial bearing and to cool and lubricate the pads 42 which provide a fluid lubricated thrust bearing against the mandrel 12. Although not shown in the illustrated embodiment, intermediate thrust rings may be installed between each journal 36 to form separate thrust faces.
(49) FIGS. 8, 9, 10 and 11 show a polymer or elastomeric reinforced roller 24 where the roller 24 is split along a split line 46 which permits the roller 24 to be opened up for installation onto its respective journal 36. In the illustrated embodiment, the reinforcement takes the form of a perforated steel band 48 encapsulated within the polymer or elastomeric material 50 of the roller 24. Perforations or holes 52 are provided in the band 48 to provide a strong bond between the outer stabiliser section and the inner bearing section. The band 48 also provides circumferential strength to the roller 24.
(50) As shown most clearly in FIG. 10, upset ends 54 or flanges are formed at the split line 46 and the upset ends 54 are provided with threaded bores 56 which accommodate mechanical fasteners in the form of cap screws 58. The cap screws 58 are screwed through the bores 56 formed in the polymer or elastomeric material 50 to clamp the upset ends 54 together to form the roller 24. The bores 56 are of smaller diameter than the heads of the cap screws 58 such that, when the cap screws 58 are screwed home, they deform the polymer or elastomeric material 50 of the roller 24, allowing the head of each cap screw 58 to bear against the steel upset ends 54. The polymer or elastomeric material 50 is selected to permit the material 50 to reform behind the heads of the cap screws 58 preventing rotation which could otherwise cause the cap screws 58 to back out of the bores 56.
(51) The steel reinforcement 48, which is substantially encapsulated within the polymer or elastomeric material 50 of the roller, is exposed at its upset end 54 along the split line 46 so that when the upset ends 54 are clamped together by the cap screws 58, they form a known internal diameter of the pad sections 42. Beneficially, this provides a repeatable clearance running fit on the journals 36 to which they are attached.
(52) In this way, it is possible to construct the apparatus 10 with offset and skewed or angled rollers 24 which will roll in a helical manner on the inner wall of the borehole or bore-lining tubular while permitting the free rotation of the mandrel 12 forming an integral part of the string S. In use, the apparatus 10 provides substantial reduction of rotational friction due to the fluid lubricated bearings, wear protection to the cased borehole due to the protective rollers 24 and thrust or transport of the string S in high angle or horizontal boreholes.
(53) It should be understood that the embodiment described herein is merely exemplary and that various modifications may be made thereto without departing from the scope of the invention.
(54) Referring to FIGS. 12 to 22 of the drawings, rather than being nested together on a short sub, the rollers may be mounted on mandrel in a spaced arrangement.
(55) In the embodiment illustrated in FIG. 12, four offset and skewed rollers 24 are provided on the mandrel 12, each roller 24 offset e.g. at 180 degrees, so that the apparatus 10 provides at least two points of contact with the wall of the borehole or bore-lining tubular as the apparatus 10 travels along the borehole wall. In this configuration, the blades 28 on the rollers 24 would not have to be synchronised as they would have sufficient space between them to permit the passage of fluids, drill cuttings and the like past them.
(56) Another embodiment of the invention is shown in FIGS. 13 to 16 of the drawings. FIG. 13 shows a perspective view of the apparatus 10. FIG. 14 shows an end view of the apparatus 10. FIG. 15 shows an end view of the apparatus 10 shown in a section of casing C. FIG. 16 shows a partial cut away view of the apparatus 10.
(57) In the embodiment illustrated in FIGS. 13 to 16, six offset and skewed rollers 24 are provided on the mandrel 12, each roller 24 offset e.g. at 120 degrees, so that apparatus 10 provides at least two points of contact with the wall of the borehole or bore-lining tubular as the apparatus 10 travels along the borehole wall.
(58) In the embodiments shown in FIG. 12 and FIGS. 13 to 16, the rollers 24 are similar or identical to the rollers 24 described and shown in FIGS. 6 to 11 and are of split-sleeve type.
(59) Referring now to FIGS. 17 to 20 of the drawings, there is shown an apparatus 10 according to another embodiment of the present invention. FIG. 17 shows a perspective view of the apparatus 10 according to this embodiment. FIG. 18 shows a side view of the apparatus shown in FIG. 17. FIG. 19 shows a side view of the apparatus shown in FIGS. 17 and 18, with traction members removed. FIG. 20 shows a partial cut-away view of the apparatus shown in FIGS. 17, 18 and 19.
(60) In the embodiment illustrated in FIGS. 17 to 20, six offset and skewed rollers 24 are provided on the mandrel 12, each roller 24 offset e.g. at 120 degrees, so that apparatus 10 provides at least two points of contact with the wall of the borehole or bore-lining tubular as the apparatus 10 travels along the borehole wall.
(61) However, in this embodiment the offset and skew is provided by machined skewed and offset sleeves 60 which slide over a recessed or reduced diameter section 62 of the mandrel 12. The reduced diameter section 62 extends along the length of the mandrel 12 to a point 64 above the lower threaded pin joint connection 14 sufficiently far back to allow for application of rig tongs (not shown) in operation and recuts of the pin connection in service, where required.
(62) The sleeves 60 are keyed to the reduced diameter section 62 of the mandrel 12 at suitable angular spacings and separated from each other by shrunk fit spacers 66. of the same or similar diameter to the non-recessed section of the mandrel 12.
(63) Beneficially, utilising rollers 24 and sleeves 60 in this way permits the apparatus 10 to be assembled at low temperature avoiding damage to elastomer bearings during assembly.
(64) The rollers 24 and spacers 66 are held in place by a top sub 68 of the same or similar outer diameter to the unrecessed mandrel 12. This box by box threaded connection top sub 68 is of sufficient length to permit the setting of slips and making and breaking connections when the apparatus 10 is being run into and pulled out of the borehole.
(65) In other embodiments of the invention, and referring now to FIGS. 21 to 33 of the drawings, the traction members may be activatable, that is configured so as to have a first, passive configuration in which the apparatus is not urged along the borehole wall and a second, active, configuration in which the traction member urges the apparatus along the inner wall of the borehole or bore-lining tubular.
(66) FIG. 21 shows a longitudinal sectional view of an apparatus 10′ according to an alternative embodiment of the present invention, having one or more activatable traction member.
(67) The apparatus 10′ has a generally cylindrical body 12′ having a throughbore 14′ for passage of fluid or tools therethrough. The body 12′ is provided with threaded box 16′ and threaded pin 18′ connections at upper and lower ends for connecting the body 12′ to drill tubulars (shown schematically as 20′, 22′). The apparatus 10′ and drill tubulars 20′, 22′ form part of a drill string for use in a high angle or horizontal borehole, such as an oil or gas exploration or production wellbore, and in use the apparatus 10′ provides for traction of the drill string as well as the reduction of downward drag and of rotational torque of the drill string in high angle or horizontal well bore drilling applications.
(68) As shown in FIG. 21, the body 12′ further comprises an upset diameter portion 24′ in which there is provided a recess or pocket 26′ for mounting a traction roller assembly 28′. The traction roller assembly 28′ comprises a traction roller 30 mounted on a carrier 32′ via a bearing shaft 34′. The traction roller 30 is mounted at an offset radial position from a central longitudinal axis C′ of the body 12′ and the diameter of the traction roller 30′ is such that the roller 30′ does not extend beyond the central axis C′. In the embodiment shown, the traction roller 30′ comprises a barrel roller, although it will be recognised that the roller 30′ may be of any suitable configuration.
(69) The carrier 32′ has a shoulder 36′ shaped to engage a corresponding shoulder 38′ of the pocket 26′, preventing removal of the roller assembly 28′ from the pocket 26′.
(70) In the embodiment shown in FIG. 21, an inner surface 40′ of the carrier 32′ may be exposed to fluid in the throughbore 14′, so that the carrier 32′ may be urged in a radially outward direction relative to the pocket 26′ from a first, passive configuration in which the roller 30′ does not contact the inner wall of the borehole to a second, active configuration in which the roller 30′ engages the inner wall of the borehole.
(71) A bonded elastomer element 42′ is provided between the carrier 32′ and the pocket 26′, the bonded elastomer element 42′ providing a seal between the carrier 32′ and the throughbore 14′ in use, while also permitted a degree of movement of the carrier 32′ between the passive and active configurations.
(72) Only a single roller assembly 28′ and pocket 26′ are shown in the sectional view of FIG. 21. However, and referring now also to FIG. 22 which shows a perspective view of the apparatus 10′, the apparatus 10′ preferably comprises three pockets 26′ and three roller assemblies 28′ circumferentially spaced at 120 degrees around the body 12′.
(73) As shown in FIG. 22, it can be seen that upset diameter body portion 24′ is formed from a number of helical blades with external passages 44′ provided to permit fluid and debris bypass around the apparatus 10′.
(74) As can be seen most clearly from FIG. 22, the apparatus 10′ is configured so that the longitudinal axis of the traction roller 30′ is skewed by between about 3 degrees to about 5 degrees relative to the longitudinal axis of the body 12′. The provision of a skew angle introduces a longitudinal component to the interaction between the traction roller 30′ and the borehole wall such that, on rotation of the body 12′, the roller 30′ will, in addition to providing a rolling contact between the apparatus 10′ and the borehole wall, provide a longitudinally directed force urging the apparatus 10′ and associated coupled drill tubulars 20′, 22′ of the drill string along the inner wall of the borehole. In the embodiment shown, the direction of skew angle is selected to provide a reverse thrust force on the borehole wall which acts to urge the apparatus 10′ in an up hole direction. However, it will be recognised that the skew angle may be selected to provide forward, downhole directed thrust force if required.
(75) To assist in understanding the mechanism of the present invention, reference is made to FIGS. 24 to 26 which show simplified perspective views showing a body and a single roller. FIG. 24 is shown for comparison and shows an arrangement having a roller mounted coaxially (no skew angle) on a body. In use, as the body rotates about its longitudinal axis, the roller about its longitudinal axis but in the opposite direction. As the roller has no skew angle with respect to the body, there is no longitudinal force component between the roller and the borehole wall and so no longitudinal movement of the body. Turning to FIGS. 25 and 26, where the roller is provided with a skew angle relative to the body, it will be recognised that the interaction between the roller and the borehole wall will now involve a longitudinal component, that is a component acting in the direction of the longitudinal axis of the body. As can be seen from FIGS. 25 and 26, where the roller is skewed in the direction shown in FIG. 25, rotation of the body in the direction shown will cause the body to be urged in the direction shown by the arrow A. Conversely, where the roller is skewed in the direction shown in FIG. 26, rotation of the body in the same direction will cause the body to be urged in the opposite direction, as shown by arrow B. As will be understood by the person skilled in the art, as a drill string is typically constructed from section of tubulars threadedly coupled together, a drill string will only be rotated in one direction to avoid the threaded coupling of the string from disengaging. Beneficially, embodiments of the present invention thus permit forward or reverse thrust to be achieved while also rotating the body in a single direction.
(76) Referring again to FIGS. 21 and 22, in order to retain the apparatus 10′ in the first, passive configuration, a collet sleeve 46′ having fingers 47′ is provided within the throughbore 14′. The sleeve 46′ is secured within the throughbore 14′ by a shear pin 48′ and a national pipe thread (NPT) seal plug 49′. Elastomeric seals or rings 51′ may be provided in grooves 53′ in the collet sleeve 46′ to isolate the section of the throughbore 14′ around the roller assembly 28′.
(77) In use, in order to activate the apparatus 10′ from the first configuration to the second configuration, an activation dart 50′ is dropped or driven down the drill string and into the apparatus throughbore 14′. A rupture disk 54′ is secured to the dart 50′ by a retainer ring 56′ to prevent fluid passage through the dart 50′ and allow the dart 50′ to be propelled through the drill string.
(78) Application or continued application of fluid pressure will overcome the shear limit of shear pin 48′ to release the collet sleeve 48′ to move relative to the body 12′ and thereby expose the carrier surface 40′ to fluid pressure sufficient to urge the carrier 32′, and thus the roller 30′, into contact with the borehole wall. The collet sleeve 46′ will travel through the throughbore and engage a shoulder 54′ provided in the throughbore 14′. Also, the collet fingers 47′ will engage a groove 56′ provided in the throughbore 14.
(79) Still further application of fluid pressure will burst the rupture disk 54′ and permit fluid or tool passage through the body 12′. Rupture of the disk 54′ may be detected as surface, providing an indication that the apparatus has set. It will be understood that this process may be repeated for each apparatus 10′, where a number of apparatus' 10′ are provided.
(80) Referring now to FIGS. 26, 27 and 28, there are shown perspective, plan and longitudinal sectional views of an apparatus 100′ according to another aspect of the present invention. The apparatus 100′ comprises a thick-walled cylindrical tool body 102′ with a throughbore 104′ and threadable attachment means in the form of threaded pin 106′ and threaded box 108′ (see FIG. 28) connections at either end for connecting the body 102′ to drill tubulars 110′, 112′ (see FIG. 28).
(81) The thick-walled cylindrical body 102′ has an upset section 114′ through which are machined fluid bypass grooves 116′ to form raised sections or pads 118′. As shown in FIGS. 26 to 28, the raised pads 118′ of the upset section 114′ extend substantially axially along the body 102′, although it will be recognized that the pads 118′ and grooves 116′ may be of any suitable configuration and may for example define a helical configuration similar to the portion 24′ of apparatus 10′ (shown in FIG. 22).
(82) Machined bays or pockets 120′ are formed in the pads 118′, into which are mounted roller assemblies 122′. One pocket 120′ and one roller assembly 122′ may be provided. However, it is envisaged that the apparatus 100′ may provide mounting for three roller assemblies 122′, for example arranged in a spaced fashion at 120 degrees around the circumference of the body 102′.
(83) Each roller assembly 122′ has a roller 124′ supported on a bearing shaft 126′, the shaft 126′ held in place at either end of the pocket 120′ by means of two tapered latch locked retention blocks 128′. The blocks 128′ are described in more detail below with reference to FIGS. 27, 28 and 29.
(84) The bearing shaft 126′ is angled or skewed with respect to the central longitudinal axis C″ of the thick walled cylindrical tool body 110′, thus skewing or applying angle to the roller 124′ mounted on the shaft 126′. In the embodiment shown, the skew angle is selected to provide forward thrust force, urging the apparatus 100′ and the coupled drill tubulars 110′, 112′ in a downhole direction. As the rotational speed of rotary drilling assemblies is normally limited between 100′ and 200 rpm and the borehole diameter of the section drilled through the reservoir is generally but not always 8.5″ (about 216 mm) or less, and the drilling rate of penetration generally below 100 ft. per minute (about 0.51 meters per second), then the skew angle required to provide efficient forward traction and transport system is relatively small, for example in the order of 0.5 degrees. However, in some circumstances it may be desirable to go higher.
(85) In the embodiment shown, the machined pocket 120′ does not extend into the throughbore 104′ of the body 102′ and so permanently defines an active configuration with the roller 124′ contacting the inner borehole wall in use. However, in alternative embodiments the pocket 120′ may be configured in a similar arrangement to that shown in FIGS. 1 and 2 which is capable of moving from a passive configuration to an active configuration.
(86) Reference is now made to FIGS. 29 to 31 of which FIGS. 29 and 30 show isometric and plan views of a roller assembly 122′ and FIG. 31 shows an exploded view. As shown, the roller assembly 122′ has two tapered latch locked retention blocks 128′ at either end of the roller shaft 126′. The blocks 128′ are configured for location within a pocket, such as the pocket 120′ provided in body 102′.
(87) To construct the assembly 122′, the roller 124′ is mounted on bearings, including one or more pressure-compensated radial bearings 130′. Pressure-compensated lubricant is held within a pressure-compensated, modular, positive pressure reservoir 132′ contained within the centre portion of one or both of the retention blocks 128′. Beneficially, the internal volume of the retention block or block 128′ may provide the facility to contain substantially more lubricant than is currently provided in rolling element tools of equivalent size, thereby increasing the life of the radial bearings in operation.
(88) The lubricant held within the positive pressured reservoirs 132′ is fed into a drilled central bore 134′ at either end of the bearing shaft and fed to the bearing by means of one or more cross-drilled hole 136′ communicating between the drilled central bore 134′ and lubrication grooves 138′ machined on the external diameter of the shaft 126′.
(89) The lubricant is retained within the bearing section of the roller 124′ by rotary seals located at either end of the roller 124′ between the external diameter of the shaft 126 and the internal diameter of the roller 124′.
(90) The end thrust loads experienced by the roller 124′ due to the traction forces may be supported by internal thrust bearings, for example contained within the pressure compensated area of the roller 124′ and/or by mud lubricated thrust bearings situated at either end of the roller 124′ outwith the sealed pressure compensated area between the roller 124′ and the bearing faces on the retention blocks 128′.
(91) The retention blocks 128′ are secured by means of cap screws 140′ passing through cap screw holes 142′ in the retention blocks 128′ and into threaded holes 143′ at the bottom of the pocket 120′. A spring-loaded latch 144′ is also installed on each retention block 128′ to provide a secondary attachment means should the cap screws 140′ fail. The spring-loaded latch 144′ locks into a recess 145′ in the pocket 120′ and can only be released for disassembly by means of a release screw 146′ inserted into a release screw hole 148′. In this arrangement, the latch mechanism 144′ is integral with the retention blocks 128′. However, as an alternative to the construction shown and described above, and with reference to FIG. 32, the latch lock 11a′ may alternatively be a separate sprung loaded component mounted higher up on the tapered retention block 128′ and held in place for assembly purposes by the release screw 146′ passing through a retention hole 150′ in the latch lock component.
(92) It should be understood that the above described embodiments describing the activatable traction member or members are also merely exemplary and that various modifications may be made thereto without departing from the scope of the invention.
(93) For example, the roller assembly 122′ may be adapted for use in an apparatus such as the apparatus 10′ shown in FIGS. 21 and 22. The retention blocks, latch lock, lubrication and bearing elements of the roller assembly 122′ may alternatively be formed in or provided on a carrier such as the carrier 32′.
(94) In addition, at least one of the body, the upset diameter body portion/blade, or roller of any of the above described apparatus' may be provided or formed with a hard facing surface or material which may, for example be used to ream or grind the borehole.
(95) Referring to FIG. 33, as an alternative to the collet sleeve described above, the sleeve may alternatively comprise a ball retent sleeve 152′. As shown in FIGS. 31 and 32, the sleeve 152′ is adapted for location in the body 12′ and comprises elastomeric seals 154′ mounted in grooves 156′ which in use straddle access port 158′ through the body 12′. As with the collet sleeve, an activation dart 160′, which may be identical to the dart 50′ described above, with rupture disk 162′ and retainer ring 164′ mounted thereon may be dropped or propelled through the drill string and seats in the sleeve 152′. Applied pressure will shear the shear pin 166′ and force the sleeve 152′ downwards (to the left in the figure) to permit fluid access to the access port 158′. The sleeve 152′ comprises a number of circumferentially spaced balls which engage with a ball detent groove to prevent further movement of the sleeve 152′.
(96) In particular embodiments, the selected skew angle may be set at surface. However, the apparatus may alternatively be configured so that the traction member is activateable from a passive configuration to an active configuration. For example, the traction member may be positioned coaxially (that is, without a skew angle) relative to the longitudinal axis of the body at surface, activation of the apparatus from the passive configuration to the active configuration providing a skew angle.
(97) FIG. 34 shows an assembly 200 according to an embodiment of the present invention. In the embodiment illustrated in FIG. 34, the assembly 200 is configured to deploy a liner 202 into a borehole having a high angle or horizontal section 204. The assembly 200 comprises a running string 206 comprising sections of drill pipe 208. A number of apparatus according to embodiments of the present invention are connected to the downhole end of the drill pipe 208. In the illustrated embodiment, three apparatus' 10 are shown, although any number of the apparatus may be employed as required. The distalmost apparatus 10 is coupled to the liner 202 by a swivel 210. In use, the string 206 is deployed into the borehole, the apparatus operable to push the string along the high angle or horizontal section 204 to assist in deploying the string 206 to the required depth. Once at the desired depth, the liner 202 may be installed and the string 206, including the apparatus' 10 may be withdrawn from the bore.
(98) FIG. 35 shows an assembly 300 according to another embodiment of the present invention. The assembly 300 is similar to the assembly 200. However, in this embodiment, the assembly 300 is configured to deploy production/completion equipment 302 and a liner hanger 303 into a borehole having a high angle or horizontal section 304. The assembly 300 comprises a running string 306 comprising sections of drill pipe 308. A number of apparatus according to embodiments of the present invention are connected to the downhole end of the drill pipe 308. In the illustrated embodiment, three apparatus' 10 are shown, although any number of the apparatus may be employed as required. The distalmost apparatus 10 is coupled to the liner 302 by a swivel 310. In use, the string 306 is deployed into the borehole, the apparatus' 10 operable to push the string 306 along the high angle or horizontal section 304 to assist in deploying the string 306 to the required depth. Once at the desired depth, the liner 302 may be installed and the string 306, including the apparatus' 10 may be withdrawn from the bore.
(99) FIG. 36 shows an assembly 400 according to another embodiment of the present invention. The assembly 400 is similar to the assembly 200 or 300. However, in the embodiment illustrated in FIG. 36, the assembly 400 is configured to deploy a hanger 402 and in-flow control valve 404 into a borehole having a high angle or horizontal section 406.
(100) FIG. 37 shows an assembly 500 according to another embodiment of the present invention. The assembly 500 is similar to the assembly 200, 300, or 400. However, in the embodiment illustrated in FIG. 37, the assembly 500 is configured to deploy a hanger 502 and sandscreen 504 into a borehole having a high angle or horizontal section 506.
(101) FIG. 38 shows an assembly 600 according to another embodiment of the present invention. In the embodiment illustrated in FIG. 38 the assembly 600 is configured to deploy a liner 602 and liner hanger 604 into a borehole having a high angle or horizontal section 606. The assembly 600 comprises a running string 608 comprising sections of drill pipe 610 as in previous embodiments. However, in this embodiment the apparatus' 10 are positioned downhole of the liner 602 and liner hanger 604, the apparatus' 10 being coupled to the liner 602 via a downhole motor 612. In use, the motor 612 is operable to drive the apparatus' 10 to pull the liner 602 and liner hanger 604 to the desire depth. Once at the desired depth, the liner 602 and liner hanger 604 may be installed and the string 608 withdrawn. The motor 612 and/or the apparatus' 10 may be left in the borehole or, where possible, retrieved.
(102) It should be understood that the above described embodiments describing the assemblies of the present invention are also merely exemplary and that various modifications may be made thereto without departing from the scope of the invention. For example, while all of the apparatus shown in the embodiments of FIGS. 34 to 38 are illustrated as apparatus 10, one or more of the apparatus may comprise an activatable apparatus according to embodiments described hereinabove.
