Pulsed high-performance drill bit and drilling tool

Description

Technical field

[0001] The present invention relates to the field of drilling and more particularly concerns a high pulsed power rotary drilling tool. Prior art

[0002] In the field of drilling, it is known to use rotary drilling tools to excavate rock. In a known solution, this type of tool has a bit with teeth that digs into the earth or rock by rotation. Such purely mechanical rotary drilling can be particularly time-consuming, especially for hard rocks.

[0003] Another known solution is to use a high-power pulsed tool that triggers electric arcs in the rock from a high-voltage electrode and a ground electrode subjected to a high potential difference, for example of the order of a few tens of kilovolts to a few hundred kilovolts. However, this solution only allows the rock to be broken at the level of the pair of electrodes, which can make the process relatively time-consuming.

[0004] CN 109577864A relates to a drill bit for a drilling tool. The drill bit comprises a drill bit body having a drilling face and a face for attaching the drill bit to a rotor assembly of the drilling tool. The central channel and the fluid circulation holes are used for the circulation of drilling fluid between the attachment face and the drilling face by opening at a circular central facial opening of the drilling face. The drill bit comprises a single high-voltage electrode, disposed in the channel passing centrally through the central facial opening, and a single ground electrode disposed around the central facial opening. The drilling face comprises a plurality of drilling teeth which appear uniformly distributed on an external surface. US 8172006 B2 relates to a drilling tool whose drill bit comprises electro-grinding electrodes.In one embodiment described in Figure 5 of this document, the drill bit has both teeth and a high-voltage electrode surrounded by an annular ground electrode. The electrical pulses are therefore concentrated only at the center of the tool head, which can limit its effectiveness and therefore presents a disadvantage. In addition, the electrodes can be damaged because they are directly exposed to the rock when the drill bit rotates. In one embodiment described in Figure 6 of this document, the drill bit has rows of teeth, a high-voltage electrode and an offset electrode arranged in place of a row of teeth. However, with this configuration, the electrical pulses are concentrated only on one side of the tool, which can limit its effectiveness and therefore presents a disadvantage. In addition, the electrodes can be damaged because they are directly exposed to the rock when the drill bit rotates.In the embodiments of Figures 35 to 37 of this prior art, the tool is toothless and non-rotatable so as not to damage the electrodes. High-voltage electrodes are distributed in the center of the front face of the drill bit and ground electrodes are distributed around the high-voltage electrodes, on the periphery of the front face of the drill bit. This configuration has the disadvantage of requiring a lot of energy to generate pulses between each of the high-voltage electrodes and a ground electrode. Then, drilling can be time-consuming with such a tool since it is only electrical and not mechanically rotating. Furthermore, it is not certain that the electrical pulses are generated efficiently, because this depends on the dielectric nature of the medium between the high-voltage electrodes and the ground electrodes.

[0005] There is therefore a need for a simple and effective solution to at least partially overcome these drawbacks. Statement of the invention

[0006] To this end, the invention firstly relates to a drill bit for a drilling tool, said drill bit comprising a drill bit body having a drilling face and a face for fixing the drill bit to a rotor assembly of the drilling tool, said drill bit body defining a through channel for the passage of the fluid flow connecting the fixing face to the drilling face and opening out at a circular central facial opening of the drilling face, the drilling face comprising an external surface connecting the central facial opening to the fixing face and from which extends a plurality of drilling members distributed uniformly on said external surface, each drilling member comprising a fin, extending radially from the external surface from the fixing face into the central facial opening,and a plurality of drilling teeth extending from said fin being arranged side by side between a first drilling tooth located at the end of the drilling face and a last drilling tooth located on the side of the fixing face, and each comprising a base and a cutting element arranged at the end of said base, the drill bit comprising a high-voltage electrode arranged in the through channel, at the center of the central facial opening set back from the first drilling tooth of each drilling member, each drilling member comprising a ground electrode placed at the end of the fin, at said high-voltage electrode, so as to extend at least partly in line with the central facial opening set back from the first drilling tooth of said drilling member.,

[0007] Each pair of electrodes formed by the high-voltage electrode and a ground electrode is configured to trigger an electric arc when said pair receives a voltage delivered to its terminals by the high-power pulse generator. Thus, by passing through the bit body to emerge at the central facial opening, the through channel allows the flow of fluid to be conveyed through the bit so that the fluid circulates continuously around the high-voltage electrode, thus forming a fluid screen having a dielectric element function allowing the electric arc to form between the high-voltage electrode and one of the ground electrodes. When the entire rotor is rotated by the turbine, the bit rotates on itself in order to mechanically dig the rock using the teeth.In doing so, the ground electrodes have a tangential velocity greater than the tangential velocity of the high-voltage electrode, which is close to zero since the high-voltage electrode is located at the center of the front face of the bit body. Thus, when a voltage is applied between the high-voltage electrode and the ground electrodes, an electric arc is generated between the high-voltage electrode and one of the ground electrodes and through the rock while the bit is rotating. Such an arrangement and operation allows the rotating bit to be as close as possible to the zone weakened by electrical fragmentation while protecting the high-voltage electrode and the ground electrodes from direct friction on the rock.The fluid circulating between the high-voltage electrode and the ground electrodes has a dual function: a dielectric element function because, between the fluid and the rock, the electric arc will favor the passage in the rock and thus fracture it and a drilling mud function because the circulation of the fluid allows the rock debris to be evacuated, conveying it to the surface. In addition, the fluid flow allows the inter-electrode zone to be cleaned.

[0008] According to one aspect of the invention, the drilling members are distributed uniformly on the external surface around the bit body in order to improve the efficiency of drilling, in particular mechanical efficiency, while allowing the flow of drilling mud between the drilling members.

[0009] Preferably, the drill body comprises at least three drilling members, preferably four, five or six drilling members to improve drilling efficiency while allowing the flow of drilling mud between the drilling members.

[0010] According to a characteristic of the invention, the fins are made from material from the external surface of the drill bit body in order to improve the strength of the drill bit and therefore the efficiency of drilling.

[0011] According to another characteristic of the invention, the tooth bases of a drilling member are made from the material of the fin of said drilling member in order to improve the solidity of the drill bit and therefore the efficiency of drilling.

[0012] Preferably, the fins extend on the outer surface in a curved manner in the direction opposite to the rotation of the drill bit for drilling efficiency.

[0013] More preferably, each drilling member comprises at least three drilling teeth, preferably four, five or six drilling teeth in order to improve drilling efficiency.

[0014] According to a characteristic of the invention, the base is of substantially cylindrical shape extending in a direction orthogonal to the axis of rotation of the drill bit in order to make the teeth solid and thus improve the efficiency of drilling and the service life of the tool.

[0015] Advantageously, the cutting elements are made of a hard and abrasive drilling material, for example from polycrystalline diamond particles bonded together, in particular of the “polycrystalline diamond compact” (PDC) type.

[0016] Preferably, the ground electrodes being identical, the high-voltage electrode and the ground electrodes each have at least partly a spherical shape in order to slow down the erosion of the electrodes. Alternatively, the electrodes could have a pointed shape, for example conical, or any other suitable shape.

[0017] In one embodiment, the electrodes each having at least in part a spherical shape, the diameter of the high-voltage electrode is at least equal to twice the diameter of each ground electrode in order to allow the formation of an electric arc between the high-voltage electrode and any of the ground electrodes.

[0018] According to one aspect of the invention, the high-voltage electrode and the six ground electrodes are made of an electrically conductive material, for example metal such as, preferably, steel.

[0019] The invention also relates to a high-power pulsed rotary drilling tool, said drilling tool comprising a stator assembly and a rotor assembly, said stator assembly comprising a hollow cylindrical body having an attachment end adapted to be connected to a drill rod and a free end, said rotor assembly comprising a turbine, mounted inside the body at the attachment end and configured to be driven by a flow of fluid supplied by the drill rod in order to drive said rotor assembly in rotation, a high-power pulse generator mounted inside the body and securely connected to the turbine and a drill bit as previously presented extending outside the cylindrical body at the free end of the stator assembly.

[0020] In one embodiment, the drilling tool further includes an electrical generator configured to convert mechanical energy from the rotating turbine into electrical energy to power the high-power pulse generator.

[0021] Preferably, the generator is mounted inside the stator assembly.

[0022] Advantageously, the drilling tool further comprises a drilling motor mounted inside the body, securely connected to the high-power pulse generator and configured to be driven by the flow of fluid having passed through the turbine.

[0023] Advantageously, the drilling tool further comprises a steering device securely connected to the drill bit and in the form of an articulated tube configured to receive the power supplied by the turbine or the increased power supplied by the drilling motor and transmit said power to the drill bit, to orient the drill bit in a given direction and to transfer the flow of fluid from the turbine to the drill bit. Brief description of the drawings

[0024] Other characteristics and advantages of the invention will become apparent from reading the description which follows. This description is purely illustrative and must be read in conjunction with the appended drawings in which: [ Fig. 1 ] There [ Fig. 1 ] is a partial side view in transparency of an embodiment of a drilling tool according to the invention. [ Fig.2 ] There [ Fig.2] is a partial side perspective view of the drill bit and tool steering device of the [ Fig. 1 ] . [ Fig.3 ] There [ Fig.3 ] is a front view of the bit of the tool of the [ Fig. 1 ] . [ Fig.4 ] There [ Fig.4 ] is a partial side perspective view of the bit of the tool of the [ Fig. 1 ], showing in particular some of the teeth. Description of the embodiments

[0025] The figures show an example of a drilling tool 1 according to the invention. The drilling tool 1 is rotary and has high pulsed powers. I) Drilling tool 1

[0026] With reference to the [ Fig. 1 ], the drilling tool 1 comprises a stator assembly 10 and a rotor assembly 20. 1) Stator assembly 10

[0027] The stator assembly 10 comprises a hollow cylindrical body 110 having a fixing end 110A, adapted to be connected to a drill rod 2, and a free end 110B. 2) Rotor assembly 20

[0028] The rotor assembly 20 includes a turbine 210, a high-power pulse generator 220, and a drill bit 230. In this preferred but non-limiting example, the drilling tool 1 further includes an electricity generator 240, a drilling motor 250, and a steering device 260. a) Turbine 210

[0029] The turbine 210 is mounted within the body 110 of the stator assembly 10 at the attachment end 110A and is configured to be driven by a fluid flow provided by the drill pipe 2 to drive said rotor assembly 20 into rotation. b) Electricity generator 240

[0030] The electricity generator 240 is configured to convert the mechanical energy of the rotating turbine 210 into electrical energy. c) High-power pulse generator 220

[0031] The high-power pulse generator 220 is mounted inside the body 110 of the stator assembly 10 and is integrally connected to the turbine 210. d) 250 drilling motor

[0032] The drilling motor 250 is of the “mud motor” type. The drilling motor 250 is mounted inside the body 110 of the stator assembly 10 and is securely connected to the high-power pulse generator 220 and is configured to be driven by the flow of fluid having passed through the turbine 210 in order to increase the torque generated by the turbine 210 and supply it to the drill bit 230 via the steering device 260. e) Steering device 260

[0033] The steering device 260 is securely connected on the one hand to the drilling motor 250 and on the other hand to the drill bit 230.

[0034] The steering device 260 is in the form of an articulated tube configured both to receive the increased power provided by the drilling motor 250 and transmit said increased power to the bit 230, to steer the bit 230 in a given direction and to transfer the flow of fluid from the turbine 210 via the drilling motor 250 to the bit 230. f) 230 drill bit

[0035] With reference to the [ Fig.2 ], the drill bit 230 is connected to the steering device 260 via a tubular connection portion 270 so as to extend outside the hollow cylindrical body 110 of the stator assembly 10 by the free end 110B. The drill bit 230 is rotatable about an axis of rotation X.

[0036] The drill bit 230 includes a drill bit body 231 having a drilling face 231A and a fixing face 231B ([ Fig.2]). The drilling face 231A is intended to come into contact with the rock in order to crush it. The fixing face 231B is configured to fix the drill bit 230 to the tubular connection portion 270 such that the drill bit body 231 and the tubular connection portion 270 are coaxially connected.

[0037] The drill bit body 231 delimits a through channel 231C for the passage of the fluid flow connecting the fixing face 231B, at the connection to the tubular connection portion 270, to the drilling face 231A, opening out at a central circular facial opening 231A1 of the drilling face 231A ([ Fig.3 ]) to allow the flow of fluid to circulate from the drill bit 230 towards the rock in order in particular to evacuate rock debris.

[0038] In reference to the Figures 3 and 4, the drill bit 230 comprises a high-voltage electrode 232C arranged in the center of the central facial opening 231A1 and having a half-sphere shape whose axis coincides with the rotation axis X. The rotation axis X passes through the center of the central facial opening 231A1 and the center of the high-voltage electrode 232C.

[0039] The bit body 231 includes an outer surface 232 extending from the central facial opening 231A1 to the attachment face 231B and from which extends a plurality of drilling (or cutting) members 233 adapted to break rock.

[0040] The drilling members 233 are preferably made from the material of the bit body 231 and are distributed uniformly on the external surface 232, around the bit body 231. In the illustrated example, which is in no way limiting, the bit 230 comprises six drilling members 233.

[0041] Each drilling member 233 includes a fin 233A formed from the outer surface 232 and extending radially in a curved manner in the direction opposite to the rotation of the drilling bit 230 for the purpose of drilling efficiency.

[0042] Each fin 233A includes a distal end extending partially into the central facial opening 231A1 and a proximal end located at the junction between the outer surface 232 and the attachment face 231B ([ Fig.2 ]). Each pair of adjacent fins 233A delimits a groove 234 allowing in particular the evacuation of drilling mud.

[0043] Drill teeth 233B are formed from the material of the fin 233A and are distributed side by side along the fin 233A from the distal end toward the proximal end. In the example of the figures, in particular at [ Fig.4 ], each drilling member 230 comprises five drilling teeth 233B.

[0044] As illustrated on the figures 2 to 4 , each drilling tooth 233B extends from the fin 233A in a direction orthogonal to the rotation axis X of the drill bit 230 so as to excavate the rock efficiently. As illustrated in the [ Fig.2 ], the assembly comprising each first drilling tooth of each drilling member 233 constitutes the end of the drill bit body 231 which first comes into contact with the rock.

[0045] The high-voltage electrode 232C is arranged set back from the first drilling teeth 233B of each drilling member 233, that is to say set back in the through-channel 231C for the passage of fluid, in order to protect it from friction of the rock during rotation of the drill bit 230.

[0046] In reference to the Figures 3 and 4, each drilling tooth 233B comprises a base 233B1 and a cutting element 233B2. The base 233B1 is made from the material of the fin 233A and is of substantially cylindrical shape extending in a direction orthogonal to the axis of rotation X of the drill bit 230. The cutting element 233B2 is arranged at the end of the base 233B1 in the direction of rotation of the drill bit 230 in order to drill the rock by rotation of the rotor assembly 20. The cutting element 233B2 is made of a hard and abrasive drilling material, for example from polycrystalline diamond particles bonded together, in particular of the “polycrystalline diamond compact” (PDC) type. The cutting elements 233B2 may be manufactured separately from the bit body 231 and then attached to the bases 233B1 using a bonding material such as a brazing alloy.

[0047] Each drilling member 233 comprises a ground electrode 233C placed at the end of the fin 233A, at the level of the high-voltage electrode 232C, so as to extend at least partly in line with the central facial opening 231A1. Like the high-voltage electrode 232C, each ground electrode 233C is arranged set back from the first drilling teeth 233B of the drilling members 233, that is to say set back in the through channel 231C for the passage of fluid, in order to protect it from friction of the rock during the rotation of the drill bit 230. Advantageously, each ground electrode 233C has a half-sphere shape whose axis can be slightly inclined in the direction of the high-voltage electrode 232C, for example between 0 and 30°, in order to improve the formation of an electric arc between the high-voltage electrode 232C and said ground electrode 233C.

[0048] The high-voltage electrode 232C and the ground electrodes 233C are made of an electrically conductive material, for example metal such as, preferably, steel.

[0049] Each pair of electrodes formed by the high-voltage electrode 232C and a ground electrode 233C is configured to trigger an electric arc when said pair receives a voltage delivered to its terminals by the high-power pulse generator 220. II) Implementation

[0050] The fixed-cut drill bit 230 may be placed in a borehole such that the cutting elements 233B2 abut the rock formation to be drilled, with the high-voltage electrode 232C and the ground electrodes 233C being protected from the rock by the drill teeth 233B.

[0051] In order to drive the rotor assembly 20, and therefore the drill bit 230, in rotation, a fluid, for example of the mud type, is sent by the drill rod 2 into the turbine 210 in order to drive it in rotation.

[0052] The power generator 240, driven by the turbine 210, then generates a charging current making it possible to recharge the capacitors of the high-frequency pulse generator 220 by means of a suitable electronic circuit.

[0053] Once passing through the turbine 210, the fluid flow passes through the drilling motor 250 which increases the power (torque) transmitted to the drill bit 230 in order to drill the rock by rotation.

[0054] As the drill bit 230 rotates, the cutting elements 233B2 scrape and shear the surface of the underlying formation. At the same time, the high-frequency pulse generator 220 periodically applies, for example between 0.5 and 50 pulses per second, preferably 30 pulses per second, a voltage between the high-voltage electrode 232C and the ground electrodes 233C to initiate the formation of an electric arc to generate rock fragments, thereby removing the significant mechanical stresses on the drill bit that would have had to be applied to generate these fragments.

[0055] By passing through the bit body 231 to open at the central facial opening 231A1, the through channel 231C allows the flow of fluid to be conveyed through the bit body 231 so that the fluid circulates continuously around the high-voltage electrode 232C, thus forming a fluid shield having a dielectric function allowing the electric arc to form between the high-voltage electrode 232C and one of the ground electrodes 233C. The flow of fluid conveyed through the bit 230 also allows the rock debris at the drilling zone to be evacuated towards the top of the wellbore.

[0056] As the drill bit rotates, the ground electrodes 233C have a tangential velocity greater than the tangential velocity of the high-voltage electrode 232C, which is close to zero since the high-voltage electrode 232C is located in the center of the drilling face 231A of the drill bit body 231. Thus, when a voltage is applied between the high-voltage electrode 232C and the ground electrodes 233C, the fluid flow surrounding the high-voltage electrode 232C creates an effective medium that ensures the formation of an electric arc in the rock between the high-voltage electrode 232C and one of the ground electrodes 233C while the drill bit 230 is rotating.

[0057] The fluid thus has a dual function: a dielectric function because, between the fluid and the rock, the electric arc will favor the passage in the rock and thus fracture it and a drilling mud function because the circulation of the fluid allows the rock debris to be evacuated, conveying it to the surface. In addition, the fluid flow allows the inter-electrode zone to be cleaned.

Claims

1. A bit (230) for drilling tool (1), said bit (230) comprising a bit body (231) having a drilling face (231A) and a face (231B) for attaching the bit (230) to a rotor assembly (20) of the drilling tool (1), said bit body (231) delimiting a through channel (231C) for passing the fluid flow connecting the attachment face (231B) to the drilling face (231A) by opening at a circular central face opening (231A1) of the drilling face (231A), the drilling face (231A) comprising an outer surface (232) connecting the central face opening (231A1) to the attachment face (231B) and from which a plurality of drilling members (233) evenly distributed on said outer surface (232) extend, each drilling member (233) comprising a fin (233A), extending radially from the outer surface (232) from the attachment face (231B) into the central face opening (231A1), and a plurality of drilling teeth (233B) extending from said fin (233A) by being disposed side-by-side between a first drilling tooth (233) located at the end of the drilling face (231A) and a last drilling tooth (233B) located on the side of the attachment face (231B), and each comprising a base (233B1) and a cutting element (233B2) disposed at the end of said base (233B1), the bit (230) comprising a high-voltage electrode (232C) disposed in the through channel (231C), in the center of the central face opening (231A1) recessed from the first drilling tooth (233B) of each drilling member (233), each drilling member (233) comprising a ground electrode (233C) placed at the end of the fin (233A), at said high-voltage electrode (232C), so as to extend at least partially in line with the central face opening (231A1) recessed from the first drilling tooth (233B) of said drilling member (233).

2. The bit (230) according to claim 1, wherein the drilling members (233) are evenly distributed on the outer surface (232) around the bit body (231).

3. The bit (230) according to any of the preceding claims, wherein the bit body (231) comprises at least three drilling members (233), preferably four, five, or six drilling members (233).

4. The bit (230) according to any of the preceding claims, wherein the fins (233A) are made as one piece with the outer surface of the bit body (231).

5. The bit (230) according to any of the preceding claims, wherein the bases (233B1) of teeth (233B) of a drilling member (233) are made as one piece with the fin (233A) of said drilling member (233).

6. The bit (230) according to any of the preceding claims, wherein the fins (233A) extend onto the outer surface (232) in a curved manner in the opposite sense to the rotation of the drilling bit (230).

7. The bit (230) according to any of the preceding claims, wherein each drilling member (230) comprises at least three drilling teeth (233B), preferably four, five, or six drilling teeth (233B).

8. The bit (230) according to any of the preceding claims, wherein the base (233B1) is substantially cylindrical in shape extending in an orthogonal direction to the axis of rotation (X) of the bit (230).

9. The bit (230) according to any of the preceding claims, the cutting elements (233B2) are made of a hard, abrasive drilling material, for example from interlinked polycrystalline diamond particles, in particular of the "polycrystalline diamond compact" (PDC) type.

10. The bit (230) according to any of the preceding claims, wherein, the ground electrodes (233C) being identical, the high-voltage electrode (232C) and the ground electrodes (233C) each have at least partially a spherical shape.

11. The bit (230) according to any of the preceding claims, the electrodes (232C, 233C) each having at least partially a spherical shape, the diameter of the high-voltage electrode (232C) is at least equal to twice the diameter of each ground electrode (233C) in order to allow the formation of an electric arc between the high-voltage electrode (232C) and any of the ground electrodes (233C).

12. A pulsed high-power rotary drilling tool (1), said drilling tool (1) comprising a stator assembly (10) and a rotor assembly (20), said stator assembly (10) comprising a hollow cylindrical body (110) comprising an attachment end (110A), adapted to be connected to a drilling rod (2), and a free end (110B), said rotor assembly (20) comprising a turbine (210), mounted inside the body (110) at the attachment end (110A) and configured to be driven by a fluid flow provided by the drilling rod (2) in order to rotatably drive said rotor assembly (20), a high-power pulse generator (220) mounted inside the body (110) and integrally connected to the turbine (210), and a bit (230) according to one of the preceding claims extending out of the cylindrical body (110) at the free end (110B) of the stator assembly (10).

13. The drilling tool (1) according to the preceding claim, further comprising an electricity generator (240) configured to convert the mechanical energy of the rotating turbine (210) into electrical energy in order to supply the high-power pulse generator (220).

14. The drilling tool (1) according to any of claims 12 or 13, further comprising a drilling motor (250) mounted inside the body (110), integrally connected to the high-power pulse generator (220) and configured to be driven by the fluid flow having passed through the turbine (210).

15. The drilling tool (1) according to any of claims 12 to 14, further comprising a steering device (260) integrally connected to the bit (230) and being in the form of a hinged tube configured to receive the power provided by the turbine (210) or the increased power provided by the drilling motor (250) and transmit said power to the bit (230), to direct the bit (230) in a given direction and to transfer the fluid flow from the turbine (210) to the bit (230).