Downhole drilling assembly

Abstract

A downhole stabilizer (5), such as a drill motor stabilizer, comprises at least one reaming means and/or reinforcing means (10). The present invention also relates to an assembly (30), such as a downhole drilling assembly (31), comprising at least one such stabilizer (5) and/or a drill bit (40,41) comprising a gauge bit (42) at or near a drilling end (45) thereof, and a connection means (46) for connecting the drill bit (40,41) to a drill motor assembly (60), wherein the drill bit gauge (42) comprises a substantially cylindrical portion having a length less than or equal to approximately 1.0 times the nominal bit diameter. The present invention also relates to a novel locking mechanism (80), such as a lock and key mechanism, to allow locking of a shaft (70), e.g. a motor drive shaft (71), through or together with a stabilizer (5).

Claims

1. A downhole drilling assembly comprising: a drill bit defining a bit gauge radius; a motor body portion; a motor shaft; and a stabiliser comprising at least one reaming means, a cylindrical body and a plurality of circumferentially spaced blades on or around an outer surface of the cylindrical body, wherein at least one of the circumferentially spaced blades is an offset blade such that the shape of the stabiliser is acentric or eccentric in relation to the motor shaft and/or motor body portion of the downhole drilling assembly and wherein the stabilizer is provided at a lower end of the motor body portion, wherein the at least one offset blade of the stabiliser sweeps an offset radius greater than the bit gauge radius; wherein a lower end portion of the stabiliser is substantially level or flush with a lower end portion of the motor body portion.

2. The downhole drilling assembly according to claim 1, wherein the stabiliser is rotationally connected to the motor shaft and/or motor body portion of the downhole drilling assembly.

3. The downhole drilling assembly according to claim 1, wherein the stabiliser comprises a drill motor stabiliser, and/or wherein the downhole drilling assembly is a drill motor assembly.

4. The downhole drilling assembly according to claim 1, wherein each blade comprises at least one sloped or inclined portion or surface extending between at least one top or outermost portion or surface of the blade and a body portion or end portion of the stabiliser at or near a first or lower end and/or a second or upper end thereof.

5. The downhole drilling assembly according to claim 1, wherein the reaming means is provided on at least one blade of the stabiliser.

6. The downhole drilling assembly according to claims 5, wherein the reaming and/or reinforcing means is provided on more than one blade of the stabiliser.

7. The downhole drilling assembly according to claim 5, wherein the reaming and/or reinforcing means is provided on the same at least one blade of the stabiliser.

8. The downhole drilling assembly according to claim 1, wherein the stabiliser comprises at least one first reaming means and/or reinforcing means provided at least at or near a first or lower end portion of the stabiliser, which first end is nearest a drill end thereof, in use.

9. The downhole drilling assembly according to claim 8, wherein the stabiliser comprises at least one second reaming means and/or reinforcing means provided at least at or near a second or upper end portion of the stabiliser, which second end is farthest from a drill end thereof, in use.

10. The downhole drilling assembly according to claim 9, wherein the stabiliser comprises at least one third reaming means and/or reinforcing means provided on at least one sloped portion of at least one blade.

11. The downhole drilling assembly according to claim 10, wherein the stabiliser comprises at least one fourth reaming and/or reinforcing means provided on at least a top portion or surface of at least one blade.

12. The downhole drilling assembly according to claim 11, wherein the at least one fourth reaming and/or reinforcing means is substantially level or flush with an outer surface at least one blade of the stabiliser.

13. The downhole drilling assembly according to claim 11, wherein the stabiliser comprises at least one fifth reaming means and/or reinforcing means provided at least partially along at least one substantially longitudinal edge of at least one blade.

14. The downhole drilling assembly according to claim 13, wherein the at least one fifth reaming means and/or reinforcing means is provided at least partially along or near an edge of at least one blade facing substantially towards a direction of rotation of the stabiliser, in use.

15. The downhole drilling assembly according to claim 13, wherein the first, second, third and/or fifth reaming means and/or reinforcing means comprises blocks and/or are made from a diamond-impregnated material.

16. The downhole drilling assembly according to claim 15, wherein the diamond-impregnated material comprises diamond-impregnated tungsten carbide.

17. The downhole drilling assembly according to claim 11, wherein the fourth reaming and/or reinforcing means comprises blocks and/or are made from a tungsten carbide material.

18. The downhole drilling assembly according to claim 8, wherein the fifth reaming and/or reinforcing means is provided on a different one of the one or more blades of the stabilizer than at least one of the first, second third and/or fourth reaming and or/reinforcing means.

19. The downhole drilling assembly according to claim 1, wherein the stabiliser is made from a low carbon alloy steel.

20. The downhole drilling assembly according to claim 1, wherein the at least one reaming means comprises a combined reaming and reinforcing means.

21. The downhole drilling assembly according to claim 1, wherein the at least one reaming means and/or reinforcing means is made of a material harder than a body of the stabiliser.

22. The downhole drilling assembly according to claim 1, wherein the assembly further comprises a drill motor assembly.

23. The downhole drilling assembly according to claim 22, wherein the stabiliser is provided at a lower end of the drill motor assembly nearest a drill end thereof.

24. The downhole drilling assembly according to claim 22, wherein the assembly is devoid of a connector or bit box between the drill bit and a lower or drilling end of the drill motor assembly.

25. The downhole drilling assembly according to claim 22, wherein the drill motor assembly comprises a deviating device.

26. The downhole drilling assembly according to claim 25, wherein the acentric or eccentric stabiliser is alignable with and/or relative to the deviating device.

27. The downhole drilling assembly according to claim 1, comprising a drill bit attachment means provided at or near a lower end portion of the motor shaft.

28. The downhole drilling assembly according to claim 27, wherein a lower end portion of the motor shaft is provided with a receiving portion into which is received the drill bit attachment means.

29. The downhole drilling assembly according to claim 1, wherein an external diameter of the stabiliser is substantially identical to a full gauge diameter of the drill bit.

30. The downhole drilling assembly according to claim 1, wherein the offset radius is in the range of 0 to +3 mm of the bit gauge radius.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments of the present invention will now be described by way of example only, and with reference to the accompanying drawings, which are:

(2) FIG. 1 a side view of a drill motor stabiliser according to a first embodiment of the present invention;

(3) FIG. 2 an enlarged side view of a drilling end of the stabiliser of FIG. 1;

(4) FIG. 2a an enlarged cross-sectional view of part of the drilling end of FIG. 2;

(5) FIG. 3 a perspective view of an upper part of the stabiliser of FIG. 1;

(6) FIG. 4 a side view of an alternative embodiment of the drill motor stabiliser of FIG. 1, showing an eccentric stabiliser.

(7) FIG. 5 a perspective view of a drill bit according to a second embodiment of the present invention;

(8) FIG. 6 a side view of a first drilling assembly comprising the stabiliser of FIG. 1 and the drill bit of FIG. 5;

(9) FIG. 6a is a cross-sectional side view of an example drilling assembly comprising the stabiliser of FIG. 1 and the drill bit of FIG.5

(10) FIG. 7 a side view of a second drilling assembly comprising a modified stabiliser similar to that of the stabiliser of FIG. 1;

(11) FIG. 8 a further side view of the drilling assembly of FIG. 7 with a drill bit removed and a key means in an engaged position;

(12) FIG. 9 a front perspective view of a lower end of a motor drive shaft and stabiliser of the drilling assembly of FIG. 7, showing the key means engaged with a locking means;

(13) FIG. 10 a cut-away side view of a lower end of the drilling assembly (stabiliser not shown) of FIG. 7, showing the key means engaged with the locking means; and

(14) FIG. 11 a side view of the drilling assembly of FIG. 6 or FIG. 7 with a drill bit removed.

DETAILED DESCRIPTION OF DRAWINGS

(15) Referring to FIGS. 1 to 4 there is shown a drill motor stabiliser 5 according to a first embodiment of the present invention. The stabiliser 5 comprises reaming means and/or reinforcing means 10.

(16) The stabiliser 5 comprises a plurality of blades 20, e.g. longitudinally extending blades, on or around an outer surface 4 thereof, e.g. circumferentially spaced.

(17) The stabiliser 5 comprises a cylindrical body 8, and the outer surface 4 comprises an outer surface of the cylindrical body 8. Each blade 20 comprises at least one top or outermost portion or surface 22.

(18) Each blade 20 also comprises at least one sloped or inclined portion or surface 23 extending between the at least one top or outermost portion or surface 22 of the blade 20 and a body portion 8 or end portion 9 of the stabiliser 5, e.g. of the cylindrical body, at or near a first or lower or drilling end 6 and/or a second or upper end 7 thereof.

(19) Typically, each blade 20 comprises at least one edge 21 between the at least one top portion or surface 22 and the at least one sloped portion or surface 23 thereof.

(20) Beneficially, the reaming means and/or reinforcing means 10 are provided on at least one blade 20 of the stabiliser 5.

(21) The stabiliser 5 comprises first reaming means 11 provided at least at or near a first or lower end portion 6 of the stabiliser 5, which first end 6 is nearest a drill end thereof, in use.

(22) The stabiliser 5 further comprises second reaming means 12 provided at least at or near a second or upper end portion 7 of the stabiliser 5, which second end 7 is farthest from a drill end thereof, in use.

(23) As can be seen from FIGS. 2 and 3, in this embodiment first and/or second reaming means 11,12 comprise reaming blocks 11a, 12a protruding or extending at least partially from an end of a top surface 22 of at least one blade 20 over or onto a sloped surface 23 thereof.

(24) The first and/or second reaming means 11,12 each have an outermost surface which is substantially planar. A portion of the outermost surface of the first and second reaming means 11,12 is substantially flush or level with the outermost surface 22 of the blade(s) 20 upon which they are provided. A further portion of the outermost surface of the first and/or second reaming means 11,12 is provided radially outward of the respective inclined surface 23.

(25) In another embodiment, the stabiliser 5 further optionally comprises third reaming means or reinforcing means 13 provided on at least one portion, e.g. the sloped portion 23, of at least one blade 20. By such provision the sloped portion 23 of a blade 20 is, in use, protected from excessive or premature wear, by e.g. undercutting.

(26) The stabiliser 5 further comprises fourth reaming means 14a or reinforcing means 14b provided on at least a top portion or surface 22 of at least one blade 20 thereof.

(27) Typically, the third 13 and fourth 14a, 14b reaming and/or reinforcing means are substantially level or flush with an outer surface 25 at least one blade 20 of the stabiliser 5.

(28) As shown in FIGS. 1 and 2, the stabiliser further comprises at least one fifth reaming means and/or reinforcing means 15 provided at least partially along a longitudinal edge 26 of at least one blade 20.

(29) In this embodiment, the at least one fifth reaming means and/or reinforcing means 15 is provided at least partially along a longitudinal edge 26 facing substantially towards a direction of rotation of the stabiliser 5, in use. By such provision, reaming performance is improved and/or the at least one blade 20 is protected from excessive or premature wear, e.g. by undercutting.

(30) Typically, the first 11, second 12, third 13 and fifth 15 reaming and/or reinforcing means comprise blocks and/or are made from a diamond-impregnated material, e.g. a diamond-impregnated tungsten carbide material.

(31) Typically, the fourth reaming means 14a or reinforcing means 14b are made from an optionally diamond-impregnated tungsten carbide material.

(32) The fourth reaming means 14a or reinforcing means 14b comprise blocks 14c made from a diamond-impregnated tungsten carbide material and blocks 14d made from a tungsten carbide material.

(33) In this embodiment, reaming blocks 14c or reinforcing blocks 14d made from different materials are provided with different shapes.

(34) Reaming blocks 14c made from a diamond-impregnated tungsten carbide material are provided in a circular, hexagonal, or octagonal shape, and reinforcing blocks 14d made from a non-reinforced tungsten carbide material are provided in a rectangular shape.

(35) In this embodiment, the reaming and/or reinforcing means 11,12,13,14a,15 comprise a combined reaming and reinforcing means, e.g. provide both a reaming and reinforcing function, whereas the reinforcing means 14b provide a reinforcing function.

(36) In this embodiment, the reaming and/or reinforcing means 11,12,13,14a,15 and/or the reinforcing means 14b are provided on one blade 20 of the stabiliser 5.

(37) In an alternative embodiment, the reaming and/or reinforcing means 11,12,13,14a,15 and/or the reinforcing means 14b are provided on more than one blade 20, e.g. every blade, of the stabiliser 5.

(38) In this embodiment, the reaming and/or reinforcing means 11,12,13,14a,15 and/or the reinforcing means 14b are provided on the same blade 20 of the stabiliser 5.

(39) In another embodiment, each of first, second, third, fourth and fifth reaming and/or reinforcing means 11,12,13,14a,15 and/or of reinforcing means 14b are provided independently on one or more blades of the stabiliser.

(40) It is understood that the reaming means 10 provided on the stabiliser 5 of the present invention may fulfil their function when the stabiliser 5 is in rotational motion, e.g. during normal drilling mode.

(41) The reaming and/or reinforcing means 11,12,13,14a,15 and/or the reinforcing means 14b are made of a material harder than the material of the body 8 of the stabiliser 5.

(42) Typically, the stabiliser 5 is made from a low carbon alloy steel, e.g. a AISI4145 steel.

(43) Advantageously, the stabiliser 5 is a downhole drill motor stabiliser.

(44) Referring to FIG. 5 there is provided a drill bit according to a second embodiment of the present invention 40 comprising a gauge bit 42 at or near a drilling end 45 thereof, and a connection means 46 for connecting the drill bit 40 to a drill motor assembly. The connection means 46, e.g. a thread connection, are provided to connect the drill bit 40 to a motor shaft of the drill motor assembly.

(45) In this embodiment, the connection means 46 comprises a thread connection, e.g. an externally threaded pin 47 configured for engaging and connecting with a receiving portion, e.g. an internal thread, of a lower end portion of the shaft. By such provision, the need for a connector, e.g. a bit box, between the drill bit 40 and the end of the motor body, e.g. motor shaft, is eliminated.

(46) Conveniently, the drill bit further comprises a neck portion 50 provided at or near an upper end of the gauge bit 42 to allow gripping, e.g. by a bit gripper.

(47) In this embodiment, the neck portion 50 comprises two diametrically opposed flat portions 55 to allow gripping, e.g. by a bit gripper.

(48) Advantageously, the drill bit 40 is devoid of a bit sleeve.

(49) Typically, the drill bit 40 comprises a substantially cylindrical portion gauge 42 having a length less than or equal to approximately 1.0 times the nominal bit diameter, and typically in the range of 1 inch to 1.0 times the nominal bit diameter.

(50) By such provision the drill bit 40 may be termed a short gauge bit 41.

(51) The drill bit gauge 42 may have a length in the range of 1 to 8, typically 2 to 6.

(52) Typically, the drill bit 42 may be made from a diamond-impregnated carbide material with a suitable binder material.

(53) Referring now to FIG. 6 there is provided a drilling assembly 30 comprising a stabiliser 5 according to the first embodiment of the present invention, a drill bit 40 according to the second embodiment of the present invention, and a drill motor assembly 60.

(54) The stabiliser 5 is provided at a lower end of the drill motor assembly 60, i.e. an end nearest a drill end 45 thereof.

(55) Typically, the drill motor assembly 60 comprises a tubular motor body portion 65 adapted for selective rotational movement, a motor shaft provided within or inside said tubular motor body portion, and a drill bit attachment means provided at or near a lower end portion of the motor shaft.

(56) Typically also, the tubular motor body portion 65 is attached and/or rotationally connected to the stabiliser 5. By such provision, rotational motion of the motor body portion 65 causes rotational motion of the stabiliser 5, e.g. during normal drilling. Conversely, absence of rotational motion of the motor body portion 65, e.g. during directional or lateral drilling, causes the stabiliser 5 to remain stationary in relation to the motor shaft.

(57) Typically, a lower end portion of the shaft is provided with an internal thread into which is received an externally threaded pin 47 of the drill bit 40.

(58) The assembly is devoid of a connector, e.g. a bit box, between the drill bit 40 and a lower or drilling end of the motor body 65, e.g. motor shaft.

(59) Conveniently, a lower end portion of the stabiliser is substantially level or flush with a lower end portion of the motor shaft.

(60) Preferably, the drill bit 40 is a short gauge drill bit 41. In the art, a short gauge bit is understood to mean a drill bit with an outer cylindrical portion the length of which measures less than or equal to approximately 1.0 times the nominal bit diameter, and typically in the range of 1 inch to 1.0 times the nominal bit diameter.

(61) Conveniently, the drill bit 40,41 comprises a neck portion 50 to allow gripping, e.g. by a bit gripper.

(62) In one implementation, as shown in FIGS. 1 to 3, the shape of the stabiliser 5 is substantially concentric in relation to the motor shaft.

(63) In this embodiment, the external diameter of the stabiliser 5 diameter is substantially identical to the full gauge diameter of the drill bit 40,41, i.e. 0 to ??, of the nominal hole size.

(64) In another implementation, as shown in FIG. 4, the shape of the stabiliser 5 is acentric or eccentric in relation to the motor shaft. The stabiliser 5 displays an offset such that an offset blade 20a of the stabiliser 5 sweeps a radius equal to or greater than the bit gauge radius. Typically, the offset radius is 0 to +3 mm of the bit gauge radius.

(65) Beneficially, the drill bit 40,41 is devoid of a bit sleeve. By such provision the drill bit relies only on the integral matrix gauge for stabilisation and the bit overhang is reduced significantly thereby improving the steerability of the motor assembly.

(66) The drill bit gauge 42 has a length in the range of 1 to 8, typically 2 to 6.

(67) The distance between a lower or drilling end of the motor body 65, e.g. motor shaft and/or of the stabiliser and the bit gauge 42 is in the range of 1 to 8, typically 2 to 6.

(68) Typically, the drill bit 40,41 is made from a diamond-impregnated carbide material with a suitable binder material.

(69) Typically the drilling assembly 30 is a downhole drilling assembly 31.

(70) Referring to FIGS. 7 to 10 there is provided a drilling assembly 30 comprising a stabiliser 5 according to a third embodiment of the present invention. The stabiliser 5 comprises a lockable means or lock and key mechanism 80.

(71) The lockable means or lock and key mechanism 80 is adapted for temporarily and/or releasably locking a drive shaft 70 through or together with a drill motor stabiliser 5.

(72) Advantageously, the drive shaft 70 is a motor drive shaft 71 and/or the stabiliser 5 is a drill motor stabiliser.

(73) By such provision a lower end portion of the shaft 70 provided underneath or inside the stabiliser 5 may be held in position while attaching or detaching a drill bit 40 to/from the shaft 70.

(74) Typically, the lockable means or lock and key mechanism comprises a lock means 90 and a key means 100.

(75) The lock means 90 comprises at least one opening, aperture or slot 91 provided in or through a portion of the stabiliser 5, and at least one receiving or lock portion 95 provided on at least one portion of the motor drive shaft 70.

(76) Conveniently, in use, the or one of the at least one openings 91 of the stabiliser 5 is aligned with the or one of the at least one receiving or lock portions 95 of the motor shaft 70.

(77) The at least one opening 91 is openably covered or protected with covering means 92, e.g. a flap or cover. Such may seek to prevent, in use, ingress, egress or gathering of debris or drilling particles in or near the opening 91.

(78) Typically, the key means 100 comprises at least one handling portion 101 and at least one engaging portion 102.

(79) Conveniently, the shape and size of the at least one opening portion 91 is such that the at least one engaging portion 102 of the key means 100 may be inserted therethrough.

(80) Conveniently, the at least one receiving or lock portion 95 of the shaft 70 is adapted for receiving the at least one engaging portion 102 of the key means 100.

(81) Typically, the at least one receiving or lock portion 95 of the shaft 70 comprises e.g. a slot, and the at least one engaging portion 102 of the key means 100 is e.g. T-shaped.

(82) Typically, the shaft 70 is provided with one or more, e.g. two, receiving or lock portions 95, optionally diametrically opposite one another.

(83) Typically also, the stabiliser 5 is provided with one or more, e.g. two, openings 91.

(84) Preferably, the drill motor stabiliser 5 is a stabiliser according to the first embodiment of the present invention.

(85) Preferably, the locking means or lock and key mechanism 80 is adapted for a downhole drill motor assembly 31.

(86) Preferably, the downhole drilling assembly 31 comprises a stabiliser 5, a drill bit 40, and a drill motor assembly 60.

(87) Referring now to FIG. 11, there is provided a drilling assembly 30,30 comprising a stabiliser 5,5 according to a first or third embodiment of the present invention, a drill motor assembly 60,60, and a drill bit according to a second embodiment of the present invention (not shown).

(88) In one implementation, the drilling motor assembly 60,60 comprises a deviating device 110,110, e.g. an offset stabiliser or a bend.

(89) When the shape of the stabiliser 5,5 of the present invention is acentric or eccentric in relation to the motor shaft 70,70 and/or motor body portion 65,65, the acentric or eccentric stabiliser 5,5 may be aligned with and/or relative to the deviating device 110,110. By such provision, deviation of the drilling assembly 30,30 by the deviating device 110,110 may be adjusted, improved and/or increased by aligning the acentric or eccentric stabiliser 5,5 with and/or relative to the deviating device 110,110. Typically, deviation will occur in a direction opposite the offset blades 20a of the stabiliser 5,5.

(90) It will be appreciated that the embodiments of the present invention hereinbefore described are given by way of example only and are not meant to limit the scope thereof in any way.