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1. WO2020115484 - APPAREIL DE FORAGE ET PROCÉDÉ DE FORAGE

Note: Texte fondé sur des processus automatiques de reconnaissance optique de caractères. Seule la version PDF a une valeur juridique

[ EN ]

APPARATUS FOR BORING AND A METHOD OF BORING

Field of the Invention

The invention relates to apparatus for boring in a bore hole, particularly apparatus of a bottom hole assembly. The invention also relates to a related method.

Background

Costs involved in drilling bore holes are high. For example, the costs involving in renting a drill rig and manning it are high. One drilling technique involves rotating diamond impregnated drill bits at high speed. The drill bits wear out periodically and have to be replaced, resulting in down time for the rig. It is an object of the present invention to reduce the amount of down time.

Summary of the Invention

According to a first aspect of the present invention, there is provided apparatus for a bottom hole assembly, for boring in a bore hole, comprising: one or more conveying means; for the or each conveying means, a plurality of cutting means, wherein the or each conveying means is arranged to move the respective plurality of cutting means in turn to an end of the conveying means at which to impact a cutting face of a bore hole, and away from the end, thereby to deepen the hole.

According to a second aspect of the present invention, there is provided an assembly for a bottom hole assembly, comprising: a frame extending in a loop; a plurality of cutting means each for impacting a cutting face of a bore hole when located at an end of the frame, wherein each cutting means includes a mount portion slidably mounted on the frame to slide around the frame; a plurality of thrust bearings fixed to the mount portion and/or the frame to facilitate sliding.

According to a third aspect of the present invention, there is provided a method of boring a hole using boring apparatus comprising one or more conveying means and, for the or each conveying means, a plurality of cutting means moved by the respective

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conveying means, comprising: causing movement of the cutting means on the or each conveying means longitudinally with respect to a boring direction, to an end of the respective conveying means at which the cutting means are located for deepening the hole and away from the end.

Brief Description of the Figures

Embodiments of the invention will not be described, by way of example only, with reference to the accompanying Figures in which:

Figure 1 is an illustrative side view of a boring assembly of a bottom hole assembly;

Figure 2 is a close-up view of a part of the boring assembly illustrated in Figure

1 ;

Figure 3 is an illustrative view of an outer side of the boring assembly, from a perspective perpendicular to the side view of the assembly in Figure 1 ;

Figure 4 is an illustrative longitudinal cross-sectional view through section B-B in Figure 5;

Figure 5 is an illustrative transverse cross-sectional view through section C-C in Figure 1 ; and

Figure 6 is a close-up view of portions of the first and second rail assemblies and two cutter members shown in the view of Figure 5.

The Figures are illustrative only and parts are not shown consistently to any particular scale.

Detailed Description of Embodiments

Embodiments of the invention relate to a boring assembly that is part of a bottom hole assembly for a drill string, in which cutting members are each conveyed to a cutting position in which to cut a cutting face of a bore hole, and away from that position.

Referring to Figures 1 to 4, the boring assembly comprises a steerable arm 8, first and second conveying means and, for each of the first and second conveying means, a

plurality of cutter members. The first and second conveying means are each for conveying a respective plurality of the cutting members 10.

The steerable arm 8 has first and second side pieces 8a, 8b and is attached to another part of the bottom hole assembly via a neck 13. The first and second conveying means are located between the first and second side pieces 8a, 8b. The first and second conveying means each includes an elongate frame mounted on the side pieces 8a, 8b providing a rail assembly 20 for the respective cutter members 10 to move on. A plurality of the cutting members 10 are mounted on each rail assembly 20. Each rail assembly 20 is arranged to extend in an elongate loop having a plane . The loop extends lengthwise with respect to the bore hole, that is, the elongate loop has greater length than width. The cutting members 10 are moveable around the respective rail assembly. The cutting members 10 are in a cutting position when located at an end 18a of the respective rail assembly 20 remote from the surface and adjacent the cutting face.

The boring assembly can progress in the bore hole so that the cutting members 10 positioned at the end 18a of each rail assembly 20 can be made to press against the cutting face at a bottom of the bore hole. Typically, the boring assembly presses the cutting members 10 at the end 18a of each rail assembly 20 against the cutting face due to gravitational force on the boring assembly and the bore hole being bored at least partially in a downward direction. Cutter portions of the cutter members extend beyond the first and second side pieces 8a, 8b to cut the cutting face by a cutting depth indicated at A-A in Figure 1. The cutting depth may be, for example, 1 cm.

Referring also to Figures 5 and 6, each rail assembly comprises first and second spaced rails 20a, 20b. Each of the cutting members 10 comprises a mounting portion 22, a cutter portion 24 and a blade 26, the blade 26 and the mounting portion 22 being delimited with a dashed line in Figure 6. The mounting portion 22 of each cutting member 10 is mounted on the rails 20a, 20b so that the cutting member 10 is moveable along the rails 20a, 20b, including in the space between the rails. The cutter portions 24 extend outwardly with respect to a middle of the loop of the rail assembly 20. The blades 26 extend inwardly with respect to the loop.

The steerable arm 8 can be steered in the bore hole by a conventional steering mechanism (not shown). The steerable arm 8 provides, for each rail assembly 20a, 20b, first and second pressure chambers 15a, 15b that each receive fluid from drill pipes (not shown) higher in the drill string, the fluid being pumped from the surface. The arm 8 and the rails 20a, 20b are fixedly coupled together. The arm 8 provides therein a plurality of nozzle holes 16 extending from each pressure chamber. The nozzle holes 16 are oriented so that fluid in the pressure chambers 15 at high pressure is expelled from the nozzle holes 16. The nozzle holes 16 and the blades 26 are respectively disposed so that expelled fluid hits the blades 26, thereby pushing the cutting members 10 along the respective rail assembly. The steering arm side pieces

8a, 8b may have cut away portions (not illustrated) facilitating moving away of the fluid.

Each rail 18a, 18b has thrust bearings 32 fixed to bearing surfaces thereof which are slid over by the mounting portions 22. Each mounting portion 22 also has thrust bearings 30 over bearing surfaces thereof that slide over the rails 18a, 18b. The bearings 30, 32 are polycrystalline diamond tablet (PDC) having a tungsten carbide substrate. Alternatively, other kinds of bearings 30, 32 may be used to reduce friction and thus heat and wear.

The bottom hole assembly further comprises a downhole motor (not shown). The downhole motor is provided to rotate the boring assembly about its length. The downhole motor may be a fluid motor. In this case, the fluid that drives the motor may be received from the surface within pipes. That fluid after passing through the fluid motor may be received at the pressure chambers 15a, 15b.

The bottom hole assembly includes a sanding ring 9. The sanding ring 9 rotates with the steering arm 8. The sanding ring 9 also includes a plurality of further cutting members 11 , which may be like the cutting members 10. The further cutting members 11 may include a polycrystalline diamond compact cutting element; for example each further cutting member 11 may include a polycrystalline diamond (PCD) top layer integrally sintered onto a tungsten carbide substrate for high performance cutting. Each further cutting member 11 is configured to sand the walls, the action of which stabilises the centre of the drilling string and reduces vibrations in the bottom hole assembly and the whole drilling string. This facilitates faster rotations of the steering arm 8, for example at greater than 2000 rpm and preferably at greater than 3000 rpm.

The bottom hole assembly further comprises other components such as a rotary steering system and measurement while drilling (MWD) components. Use of these will be known to a person skilled in the field of technology. The steerable arm 8 can be steering in the boring process according to the data acquired by an MWD system. This may include a geo-navigation option. The steering may be implemented by selectively switching on and off or selectively slowing movement of the cutting members 24 about one or other of the first and second rail assemblies 20 during operation. This is achieved by switching off or slowing flow of fluid pushing the cutter members 24 on the selected rail assembly.

The MWD components may generate data indicative of the speed of each conveyor, pressure and temperature. The data collected is used in real-time numerical modelling for automated control of fluid flow rates and rotational speed of the steering arm.

The first and second rail assemblies 20 are located in parallel planes. The cutter members 10 are mounted on the first and second rail assemblies 20 and the nozzle holes 16 are oriented such that cutting members 10 mounted on the first rail assembly move around the rail assembly in one direction and the cutting members 10 mounted on the second rail assembly move around the rail assembly in the other direction. Since the first and second rail assemblies 20 are coupled together, forces created about the lengths of the first and second rail assemblies 20 are thus balanced.

In variant embodiments, the cutting mechanism may include only a single conveying mechanism, or may include greater than two conveying mechanisms. Also, any one conveying mechanism may in variant embodiments be operated independently of any other conveying mechanism.

The cutter portion 24 of each cutting member is shaped to separate material from the cutting face of the bore hole, for example by cutting and shearing. Each cutting portion 24 may be a polycrystalline diamond compact cutting element; for example each cutting portion 24 may include a polycrystalline diamond (PCD) top layer integrally sintered onto a tungsten carbide substrate for high performance cutting. Embodiments of the invention are not limited to use with any particular material in the cutting element. Embodiments are also not limited to any particular shape of cutting portion, which can be determined by the skilled person.

In operation, the boring assembly extends lengthwise in the boring hole. Fluid is pumped into the pressure chambers 15a, 15b in the interior of the arm 8 and expelled at high pressure from the nozzle holes 16 onto the blades 26, which results in the cutter members 10 being pushed along the rail assembly 20. The boring assembly is also simultaneously rotated about its length by the downhole motor. The boring assembly moves, typically downwardly due to gravity, so that the cutter members 10 at the end 18a of the rail assembly 20 impacts the cutting face at the bottom of the bore hole, and thus the cutting face is cut. The cutter members 10 move continuously along the rail assembly 20. The cutter members 10 heat while cutting at the end 18a of the rail assembly. They cool when not located at the end 18a. The fluid expelled by the nozzle holes 16 pushes material cut from the cutting face up the bore hole to the surface. In addition, the fluid cools the cutter members 10.

In the embodiments described above, the cutter members 10 are not coupled to one another. In variant embodiments, the cutter members 10 may be linked, so there is pull between adjacent cutter members 10 as they move along the rail assembly 20.

In a variant embodiment, each conveying means may include a frame and a track, belt or chain movable in an elongate loop, supported by the frame. In this case, the moveable track, belt or chain has on one side thereof the blades affixed thereto. The cutting portions are mounted on the other side of the track, belt or chain. Movement of the track, belt or chain may be driven by the fluid being directed at the blades, as described above.

In the embodiments described above, the cutter members 10 are moved by high pressure fluid ejected from the nozzle holes 16. Embodiments of the invention are not limited to any particular way in which the cutter members 10 are made to move in a loop. For example, instead of the cutting members 10 each including a blade, they may be each attached to a line or chain that extends with the rail assembly. In this

case, a motor may be provided to cause the line or chain to move around the rail assembly. Such a motor may be powered by electricity, for example carried from the surface. Alternatively, the motor may be pneumatically powered.

In variant embodiments, the boring assembly may be arranged so that the cutter members 10 can be moved around each rail assembly in both directions, that is, in one direction for one period and then in the reverse direction for another period. This may be advantageous as different directions would result in different wear on the cutter portions 24, resulting in the cutter portions lasting longer. Reversing direction of movement of the cutter members 10 is simple when movement of the cutter members is driven by an electric motor, for example, as will be clear to the skilled person. When the movement of the cutter members 10 is driven through directing of high-pressure fluid at the blades 16, changing of direction of movement may be achieved by providing of alternate nozzles and an arrangement of valves operable to open and close to control fluid so that the fluid exits via nozzles disposed to drive the blades in one direction or the fluid exits via nozzles disposed to drive movement of the blades in the opposite direction. In this case, as can be seen in Figure 4, the blades can be shaped to allow driving in both directions.

A length of the rail assembly may be from 1000mm to 2500mm. A width of the rail assembly may be about 180mm to 1000mm. Embodiments are not limited to these ranges and may be longer or shorter in length and wider or narrower in width. The downhole motor may spin the boring assembly about its length at from about 70rpm, preferably from about 1500, to about 3000 rpm.

As will be clear to the person skilled in the art, variant modifications can be made to the embodiments described above while remaining within the scope of the claims.

The applicant hereby discloses in isolation each individual feature or step described herein and any combination of two or more such features, to the extent that such features or steps or combinations of features and/or steps are capable of being carried out based on the present specification as a whole in the light of the common general knowledge of a person skilled in the art, irrespective of whether such features or steps or combinations of features and/or steps solve any problems disclosed herein, and without limitation to the scope of the claims.