PARTICLE CONCENTRATING DEVICE, CONCENTRATOR ELEMENT AND ASSEMBLY THEREOF, METHOD FOR INCREASING CONCENTRATION, METHOD FOR DIRECTIONAL DRILLING AND USE OF THE ASSEMBLY

Abstract

The invention relates to increasing a concentration of particles (92) in a circumferentially enclosed stream (90) of a fluid mixed with the particles in a target area (90ct) of a cross-section (90c) of the stream transverse to a flow direction (90f) of the stream. Deflecting surfaces (31.1, 31.2, 31.3) are arranged in the stream to extend over respective angular zones (30α1, 30α2, 30α3) with respect to an axis (la) through the target part. The deflecting surfaces slant in the flow direction in a direction from the circumference of the stream towards the target area, and define angularly in between them multiple bypass openings (32.1, 32.2, 32.3) which extend over angular zones complementary (30β1, 30β2, 30β3) to the angular zones over which the deflecting surfaces extend, and which are larger than the particles. The deflecting surfaces deflect at least a part of the particles inwardly towards the axis. A target part (90t) of the stream with the target cross-section around the axis is discharged through an outlet (20), and a remaining part (90r) is discharged through the openings, between the target part and the circumference of the stream, such as to discharge the stream as composed of the target part and the remaining part. The invention relates to an assembly comprising a circumferential enclosure and a particle concentrating device, a particle concentrating device, a concentrator element, a method for increasing a concentration of particles, a method for directional drilling and the use of the assembly.

Claims

1-24. (canceled)

25. An assembly comprising: a circumferential enclosure for accommodating a stream of a fluid mixed with particles, the stream having a cross-section defined by the circumferential enclosure transverse to a flow direction of the stream; and a particle concentrating device that extends around an axis parallel to the flow direction, and that is arranged inside and connected to the circumferential enclosure, wherein the particle concentration device is configured for increasing a concentration of the particles in a target area of the cross-section of the stream, the target area being defined by an outlet of the particle concentrating device arranged at a downstream end thereof and having a cross-section corresponding to the target area, wherein the device is arranged inside the circumferential enclosure to discharge within the circumferential enclosure the stream as being composed of a target part, discharged by the outlet, and a remaining part, wherein the particle concentrating device comprises multiple deflectors, the deflectors each having a deflecting surface, and wherein the deflecting surfaces: are arranged about the axis, slanting in the flow direction in a direction from the circumferential enclosure towards the axis, for deflecting a part of the particles towards the axis, and thus towards the target area; extend over respective angular zones of the device with respect to the axis, the angular zones each being defined by side edges of the respective deflecting surface, the deflecting surfaces together extending over a collective angular zone between the angularly most remote side edges thereof, the angular zone covering a majority of the angular range around the axis; and define between the side edges thereof one or more bypass openings which thereby extend over angular zones complementary to the angular zones over which the deflecting surfaces extend, wherein, in operation of the device, the deflecting surfaces together are configured for forming the target part discharged by the outlet of the device, and wherein the bypass openings are together configured for discharging the remaining part of the stream between the circumferential enclosure and the outlet, and wherein respective ones of the deflectors are part of multiple concentrator elements of the device which are successively arranged in the flow direction, wherein each concentrator element has one or more of the deflectors, or wherein the deflectors are all part of a single concentrator element.

26. The assembly according to claim 25, wherein the circumferential enclosure is suitable for accommodating a stream of drilling fluid mixed with abrasive particles.

27. The assembly according to claim 25, wherein the side edges of each deflecting surface extend in an axial plane comprising the axis.

28. The assembly according to claim 25, wherein the device comprises multiple axial sections, including at least an upstream axial section and a downstream axial section, wherein each deflecting surface and each opening axially extends along at least one respective axial section, and wherein over the downstream axial section at least one of the deflecting surfaces extends, the at least one of the deflecting surfaces being distinct from each deflecting surface extending over the upstream axial section and extending over an angular zone that is distinct from an angular zone over which a deflecting surface extending along the upstream axial section extends.

29. The assembly according to claim 28, wherein the device comprises for each axial section a respective concentrator element, of which the respective deflectors have the deflecting surfaces extending over each respective axial section.

30. The assembly according claim 25, wherein the concentrator elements of the device are nested along the axis, and wherein at least a most upstream one of the concentrator elements is with a downstream axial part thereof inserted into a downstream one of the concentrator elements, such that an upstream axial part of the upstream concentrator element protrudes from the downstream concentrator element, and, if present, forms the upstream axial section.

31. The assembly according to claim 30, wherein the downstream axial part is arranged concentrically inside the upstream axial part of the downstream concentrator element.

32. The assembly according to claim 25, wherein the deflecting surfaces of the device together extend over at least a majority of the angular range around the axis.

33. The assembly according to claim 25, wherein the deflecting surfaces and the one or more bypass openings of each of the concentrator elements, define between them a frustum around the axis, the target area forming the top of the frustum.

34. The assembly according to claim 33, wherein the frustum is a conical frustum rotationally symmetric with respect to the axis.

35. The assembly according to claim 25, wherein the deflecting surfaces in each concentrator element are exactly one deflecting surface, and wherein the number of concentrator elements is exactly two or three.

36. The assembly according to claim 25, wherein the deflecting surfaces in each concentrator element are exactly four deflecting surfaces, and wherein the number of concentrator elements is exactly two or three.

37. The assembly according to claim 35, wherein the angle of the angular zone over which each deflecting surface extends is between 140 and 200 degrees.

38. The assembly according to claim 29, wherein the separate concentrator elements are at least geometrically substantially equal to one another.

39. The assembly according to claim 25, wherein the particle concentrating device comprises the multiple concentrator elements, and the respective concentrator elements are angularly movable relative to one another so that the deflecting surfaces are angularly displaceable relative to one another.

40. The assembly according to claim 39, wherein the device further comprises one or more actuators, operative between the concentrator elements, and configured for angularly displacing the associated deflecting surfaces relative to one another.

41. The assembly according to claim 25, wherein the particles have an effective diameter in the range of 0.8-1.2 mm, and wherein the openings each have a smallest diameter larger than at least approximately three times a largest diameter of the particles.

42. The assembly according to claim 25, wherein the target area is within a center portion of the cross-section of the stream, so that the target portion of the stream as discharged by the device is encircled by the remaining portion.

43. A particle concentrating device, configured for use in the assembly according to claim 42, wherein the circumferential enclosure is a tube of a drill string, or an internal space of a drill bit, the concentrating device being configured to extend around an axis parallel to the flow direction, for being arranged inside and connected to the circumferential enclosure, wherein the particle concentration device is configured for increasing a concentration of the particles in a target area of the cross-section of the stream, the target area being defined by an outlet of the particle concentrating device arranged at a downstream end thereof and having a cross-section corresponding to the target area, wherein the device is arranged inside the circumferential enclosure to discharge within the circumferential enclosure the stream as being composed of a target part, discharged by the outlet, and a remaining part, wherein the particle concentrating device comprises multiple deflectors, the deflectors each having a deflecting surface, and wherein the deflecting surfaces: are arranged about the axis, slanting in the flow direction in a direction from the circumferential enclosure towards the axis, for deflecting a part of the particles towards the axis, and thus towards the target area; extend over respective angular zones of the device with respect to the axis, the angular zones each being defined by side edges of the respective deflecting surface, the deflecting surfaces together extending over a collective angular zone between the angularly most remote side edges thereof, the angular zone covering a majority of the angular range around the axis, and define between the side edges thereof one or more bypass openings which thereby extend over angular zones complementary to the angular zones over which the deflecting surfaces extend, wherein, in operation of the device, the deflecting surfaces together are configured for forming the target part discharged by the outlet of the device, and wherein the bypass openings are together configured for discharging the remaining part of the stream between the circumferential enclosure and the outlet, and wherein respective ones of the deflectors are part of multiple concentrator elements of the device which are successively arranged in the flow direction, wherein each concentrator element has one or more of the deflectors, or wherein the deflectors are all part of a single concentrator element.

44. A method for increasing a concentration of particles in a circumferentially enclosed stream of a fluid mixed with the particles, in a target area of a cross-section of the stream transverse to a flow direction of the stream, the method comprising the steps of: providing the stream of the fluid mixed with the particles; providing deflecting surfaces and arranging the deflecting surfaces in the stream, such that the deflecting surfaces: extend over respective angular zones with respect to an axis through the target area of the stream cross-section; slant in the flow direction in a direction from the circumference of the stream towards the target area; and define angularly in between them multiple bypass openings, which extend over angular zones complementary to the angular zones over which the deflecting surfaces extend, and which each have a smallest diameter larger than an effective diameter; deflecting, by means of the deflecting surfaces at least a part of the particles inwardly towards the axis; and discharging a target part of the stream with the target cross-section around the axis, and discharging, through the openings, a remaining part of the stream between the target part and the circumference of the stream, such as to discharge the stream as composed of the target part and the remaining part.

45. The method according to claim 44, further comprising the step of using a particle concentrating device, wherein the step of providing deflecting surfaces and arranging the deflecting surfaces comprises arranging the device in the stream by connecting the device to a circumferential enclosure of the stream.

46. The method according to claim 44, further comprising the step of using a particle concentrating device, the particle concentrating device comprising multiple concentrator elements, the method comprising, prior to the step of deflecting, the step of assembling the device, the step of assembling comprising the steps of: arranging two or more of the multiple concentrator elements successively in the flow direction; and angularly arranging the two or more of the multiple concentrator elements with respect to one another such that the deflecting surfaces are at least partially angularly offset from one another to together extend over a collective angular zone covering at least a majority of an angular range around the axis.

47. The method according to claim 46, further comprising the step of modulating an extent of an increase of the concentration of the particles in the target area of the cross-section of the stream, the step of modulating further comprising the steps of: arranging one or more of the multiple concentrator elements along the flow direction in precession or succession to the two or more of the multiple concentrator elements of the device; and/or angularly moving one or more of the multiple concentrator elements with respect to one or more other of the multiple concentrator elements such as to increase or decrease the total angular range around the axis over which the angular zones over which the deflecting surfaces of the concentrator elements together extend.

48. The method according to claim 44, wherein the fluid is a drilling fluid and the particles are abrasive particles for abrasive jet drilling, with an effective diameter of 0.8-1.2 nm.

49. A method for directional drilling comprising the steps of the method according to claim 48, further comprising the step of varying the extent of erosion of a borehole bottom along azimuthal positions thereof, comprising selectively directing the target part of the stream into impingement with the borehole bottom at a determined range of the azimuthal positions in the form of an abrasive jet.

50. The method according to claim 49, wherein the varying of the extent of erosion of a borehole bottom is performed in a drill bit, by selectively directing, in dependence of an azimuthal position of one or more abrasive jet nozzles of the drill bit which move along the azimuthal positions of the borehole bottom, at least the target part of the stream towards the one or more of the nozzles: by stationarily directing the target part of the stream towards the determined azimuthal range and aligning the one or more of the nozzles with the directed target part only when the one or more of the nozzles are within the determined azimuthal range; or by moving the target part of the stream along with the one or more of the nozzles along the azimuthal positions of the borehole bottom and directing the target part into the one or more of the nozzle, by alignment therewith, only when the one or more of the nozzles are within the determined azimuthal range.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0164] In the drawings:

[0165] FIGS. 1a-k illustrate schematically a first and a second embodiment of a device according to the invention, and a first embodiment of a concentrator element according to the invention;

[0166] FIGS. 2a-f illustrate schematically a third embodiment of a device according to the invention, and a second embodiment of a concentrator element according to the invention;

[0167] FIGS. 3a-d illustrate schematically a third embodiment of the invention;

[0168] FIGS. 4a-c illustrate schematically the second embodiment of the invention while increasing a concentration of particles in a stream;

[0169] FIGS. 5a-d illustrate schematically a device according to the invention while being used in a sub of an abrasive jet drilling system; and

[0170] FIGS. 6a-f illustrate schematically a device according to the invention while being used in a sub and a drill bit of an abrasive jet drilling system.

DETAILED DESCRIPTION OF EMBODIMENTS

[0171] FIG. 1d illustrates schematically a front and top view of a first embodiment of a particle concentrating device 1 according to the invention. The first embodiment is furthermore illustrated in FIGS. 1f-i. In FIGS. 4a-c the first embodiment is shown while increasing a concentration of particles 92 in a stream 90 of a fluid 91 mixed with the particles 92 in a target area 90ct of a cross-section 90c of the stream 90 transverse to a flow direction 90f of the stream 90. The shown embodiments are suitable for use with a stream 90 wherein the particles 92 are sphere-shaped abrasive particles 92 with an effective diameter of approximately 1 mm, and the fluid is drilling fluid 91, as is the case in FIGS. 4a-c. In these figures six example particles 92 are illustrated of which the size is exaggerated, for illustrating possible flow trajectories thereof while passing the device 1. FIG. 4a is a partial front view with a partial cross-section of the stream 90 through a channel, and FIGS. 4b,c are top views of the cross-sections C-C and D-D indicated throughout the figures.

[0172] As shown most clearly for the respective embodiments in FIGS. 1a,d,e, FIGS. 2a,d, FIG. 3a, the device 1 according to either embodiment of the device 1 has an axis 1a running there through in a plane of the flow direction 90f.

[0173] The device 1 according to either embodiment comprises an inlet element 10 defining an inlet to the device, an outlet element 20 defining an outlet of the device, and a body 30. The inlet element 10 is arranged around the axis 1a for receiving the stream 90, and has an inner cross-section 10c approximately equal to the cross-section 90c of the stream. Its inner diameter 10di is approximately 44 mm and its outer diameter 10do is approximately 50 mm. Its axial length 10h is approximately 5 mm. The outlet element 20 is arranged around the central axis 1a downstream of the inlet element 10 and has an inner cross-section 20c equal to the target cross-sectional part 90ct, for discharging a target part 90t of the stream 90. The inner diameter 20di of the outlet is approximately 16 mm and its axial length 20h is approximately 13 mm.

[0174] The body 30 interconnects the inlet element 10 and the outlet element 20, for forming in the flow direction 90f the target part 90t of the stream 90 while discharging a remaining part 90r of the stream. In the fourth embodiment the axial length 30h of the body 30 is approximately 55 mm.

[0175] In the first, second and third embodiment, the body 30 is made out of separate concentrator elements 1.1, 1.2, 1.3 in the manner shown in FIGS. 1c and 2c and discussed in more detail later. In these embodiments the axial length of the body 30 is determined by the length 1.1bh of separate concentrator elements 1.1, 1.2, 1.3, which is approximately 60 mm, the axial length 40h of spacer element 40, which is approximately 13 mm, the axial length 1.1h of the element inlets 1.1i, which is approximately 5 mm, and the number of concentrator elements 1.1, 1.2, 1.3 of the device 1—i.e. two in case of the first and third embodiment and three in the case of the second embodiment.

[0176] The body 30 of the device 1 has multiple axial sections 30.1, 30.2, 30.3. The first and fourth embodiment have exactly two axial sections 30.1, 30.2. The second and third embodiment have exactly three axial sections 30.1, 30.2, 30.3.

[0177] As shown in FIG. 4a for the first embodiment of the device, which has two axial sections 30.1, 30.2, the axial sections 30.1, 30.2 succeed one another in the flow direction 90f. As can be verified from FIGS. 1e, 2a,d and 3a is also the case for the second, third and fourth embodiment.

[0178] The device according to either embodiment comprises multiple deflectors with respective deflecting surfaces 31.1, 31.2, 31.3. Each axial section 30.1, 30.2, 30.3 has one or more deflecting surfaces 31.1, 31.2, 31.3 extending thereover. The axial sections 30.1, 30.2 of the first and fourth embodiment each have exactly one respective deflecting surface 31.1, 31.2. The axial sections 30.1, 30.2, 30.3 of the second embodiment also each have exactly one respective deflecting surface 31.1, 31.2, 31.3 extending thereover. In the third embodiment, the axial sections 30.1, 30.2, 30.3 each have exactly four respective deflecting surfaces 31.1, 31.2, 31.3 extending thereover.

[0179] As shown best in the top views in the figures, the deflecting surfaces 31.1, 31.2, 31.3 of each axial section each extend over respective angular zones 30α1, 30α2, 30α3 of the body 30 with respect to the axis 1a. The angular zones are defined by edges 31.1e, 31.2e, 31.3e of the deflecting surfaces, which are indicated for the first and second embodiment in FIGS. 1d,e, respectively. The edges 31.1e, 31.2e, 31.3e extend in a plane of the axis 1a.

[0180] In each embodiment the deflecting surfaces 31.1, 31.2, 31.3 each slant towards the axis 1a in the flow direction 90f for deflecting a part of the particles 92 towards the axis. The deflecting surfaces 31.1, 31.2, 31.3 each define between the edges 31.1e, 31.2e, 31.3e thereof one or more bypass openings 32.1, 32.2, 32.3 which thereby extend over angular zones 30β1, 30β2, 30β3 complementary to the angular zones 30α1, 30α2, 30α3 over which the deflecting surfaces extend. The angular zones are illustrated in the schematic top views of the cross-sections C-C and D-D for the shown embodiments. In some of the figures, the bypass openings of the device are indicated by a dotted shading with low density—with the mere purpose of clarifying their locations and extension.

[0181] As can be verified from the figures, the deflecting surfaces 31.1, 31.2, 31.3 define together with the bypass openings 32.1, 32.2, 32.3 a space there between which is in the form of a frustum, namely a conical frustum.

[0182] The deflecting surfaces 31.1, 31.2, 31.3 are in each embodiment together configured for the forming of the target part 90t of the stream 90 and together extend over a collective angular range defined by the angularly most remote edges 31.1e, 31.2e, 31.3e relative to the axis 1a which covers the majority of the angular range around the axis 1a. See for example the top views of the cross-sections C-C and D-D in FIGS. 1g, 2f, and 3c. For example, in the embodiment of FIG. 1d, the angular range of the deflecting surface 31.1

[0183] The bypass openings 32.1, 32.2, 32.3 are together configured for the discharging of the remaining part 90r. The bypass openings 31.1, 31.2, 31.3 each have a smallest diameter 32.1d, 32.2d, 32.3d of at least approximately five times the diameter of the particles of the stream for which the concentrating device 1 is suited.

[0184] In the first, second, and fourth embodiment this smallest diameter is approximately 16 mm, substantially corresponding to the inner diameter 20di of the outlet element 20. In the third embodiment the smallest diameter is approximately 10 mm.

[0185] It is noted that the dimensions mentioned in relation to the shown embodiments form merely one option out of a large range of possibilities for the intended particle size of these embodiments. Furthermore, for other particle sizes and fluids, the device may be scaled accordingly in order to obtain the same or a similar concentrating effect. For the same or other particle sizes and fluids, dimensioning and spatial arrangement may be adapted to either enhance or reduce the concentrating effect of the device 1 towards the target section 90t of the stream 90 as desired.

[0186] In the fourth embodiment, the body 30 of the device 1 is unitary—i.e. is made out of one piece.

[0187] In the first, second and third embodiment, the body 30 of the device 1 comprises for each axial section 30.1, 30.2, 30.3 a respective separate hollow open-ended concentrator element 1.1, 1.2, 1.3. Each respective concentrator element 1.1, 1.2, 1.3 comprises the deflectors having the deflecting surfaces 31.1, 31.2, 31.3 and bypass openings 32.1, 32.2, 32.3 of the respective axial section 30.1, 30.2, 30.3.

[0188] For the first and second embodiment, FIGS. 1a,b show, respectively in a front view and a top view of cross-section C-C, a first body element 1.1 of the device 1, which comprises a deflector with a first deflecting surface 31.1 and a first opening 32.1 of the device 1. The first body element 1.1 comprises a body element inlet 1.1i, a central axis 1.1a, and a body element outlet 1.10.

[0189] As is indicated in FIG. 1c, for forming the device 1 according to the first embodiment of the device 1 shown in FIGS. 1d,f-i, the first concentrator element 1.1 is inserted with a downstream part 1.1d thereof into a second concentrator element 1.2. The second concentrator element 1.2 is identical with the first concentrator element 1.1, and comprises a second deflecting surface 31.2 and a second bypass opening 32.2. The concentrator elements 1.1 and 1.2 are successively arranged in the intended flow direction 90f such that their axes 1.1a collide to form the axis 1a of the device 1. The second concentrator element 1.2 is angularly arranged with respect to the first concentrator element 1.1 such that the deflecting surfaces are angularly offset from one another by an angle of 180° around the axis 1a—see the top views of cross-sections C-C of the elements 1.1, 1.2 in FIG. 1c, of cross-sections C-C and D-D through the device in FIG. 1g and the top views of the device 1 in FIGS. 1d,i. As may also be verified therefrom, the downstream axial part 1.1d of the first concentrator element 1.1 is arranged concentrically inside the successive second concentrator element 1.2.

[0190] The inlet element 1.1i of the first concentrator element 1.1 forms the inlet element 10 of the device 1. The inlet element 1.1i, and therefore, the inlet element 10, is formed by a circumferential flange at the upstream end of the first concentrator element 1.1. The outlet element of the second concentrator element 1.2 forms the outlet element 20 of the device 1.

[0191] The outlet element 20 defining a cylindrical internal space over an axial length 20h is provided for rectifying the flow of the particles 92 and the fluid 91 to follow parallel stream lines—i.e. for synchronizing the flow directions of the fluid 91 and the particles 92.

[0192] The spacer element 40 in the form of a hollow, short tube is arranged between the inlet element 1.1i of the first concentrator element 1.1 and the inlet of the second concentrator element 1.2. The spacer element 40 is shown individually in FIG. 1k and has an axial length 40h of approximately 13 mm, so as to maintain an axial distance between the inlets of the body elements 1.1 and 1.2 such that in the device 1, the radial distance between the deflecting surfaces 31.1 and 31.2 is at least five times the particle diameter of 1 mm. As shown in FIGS. 1d,f-i the first axial section 30.1 of the device 1 is formed only by an upstream part 1.1u of the first concentrator element 1.1 which protrudes above the second concentrator element 1.2. The axial length 40h of the spacer element 40 determines the axial length of the first axial section 30.1. The second axial section 30.2 is formed by the second concentrator element 1.2, and additionally by the downstream part 1.1d of the first concentrator element 1.1.

[0193] As visible from the top views of the cross-sections C-C in FIG. 1c of the body elements 1.1, 1.2 and from the top views of the cross-sections C-C and D-D of the device 1 in FIG. 1g, the deflecting surfaces 31.1, 31.2 together extend over a majority of the angular range around the central axis 1a—the respective angular zones 30α1 and 30α2 are diametrically opposite and together extend over around 350 degrees.

[0194] The angular zones 30α1, 30α2 over which the directing surfaces 31.1, 31.2 of both respective axial sections extend, are thus slightly smaller than the angular zones 30β1, 30β2 over which the bypass openings 32.1, 32.2 extend. Furthermore, the angular zones 30α1, 30α2 are respectively completely inside the angular zones 30β2, 30β1, so that the bypass openings 32.1, 32.2 overlap over angular zones 32βo of around 5°, resulting in corresponding axial slits 32o of the device 1.

[0195] In the first embodiment, the remaining part 90r of the stream 90 is thus discharged from the device 1 through the bypass openings 32.1, 32.2 partly via the annular space between the concentrator elements 1.1, 1.2 and partly directly via angular slits 32o.

[0196] The outlet elements 1.1o of the concentrator elements 1.1, 1.2 are provided with an axially and tangentially bounded opening. The opening in the outlet element 1.1o of the first concentrator element 1.1 enables particles 92 between the outlet element 1.1o of the first concentrator element 1.1 and the deflecting surface 31.2 of the second concentrator element 1.2 to move into the outlet element 20 of the device 1 such as to end up in the target stream part 90t, thereby substantially preventing accumulation of these particles 92 between the outlet element 1.1o and the deflecting surface 31.2.

[0197] The outlet element 20 is provided with a shape adapter element 21 enclosing the outlet element 20. It is shown dashed in FIG. 1c on the second concentrator element as it is only provided to the outlet element of the second body element 1.2 in the first embodiment and not in the second embodiment. The shape adapter element 21 is shown individually in FIGS. 1j and 1s by its shape configured to convert the cross-section 90ct of the target stream portion 90t of the stream 90 from a substantially circular shape to a substantially square shape. The target part 90t is enabled to spread over the square shaped cross-section by means of the opening in the outlet element 20. As is illustrated in FIG. 5d, the square shaped cross-section of the target part 90t discharged from the shape adapter element 21 enables that movement of an inlet of a channel ch1, or of another part or device, which is to be arranged downstream of the outlet element 20 and the adapter element 21, with a corresponding square or rectangular cross-section linearly along an edge of the square causes this inlet to overlap with the now square shaped target part 90t with a cross-sectional area that scales linearly with the movement. As a result, an amount of particles 92 received of the concentrated target stream part 90t can be adjusted linearly by the movement of the channel ch1. This possibility may make regulation of the amount of particles 92 flowing into the channel ch1 more predictable and accurately controllable. Such regulated inflow of particles 92 into a downstream channel ch1 may be desired in applications of abrasive jet drilling, wherein modulation of the concentration of the abrasive particles 92 is used to obtain a difference in the erosive power between azimuthal sections of a borehole for directing the borehole towards the less eroded azimuthal section. This will be discussed below in relation to FIGS. 5a-c and 6a-e.

[0198] As is indicated in FIG. 1c, for forming the device 1 according to the second embodiment of the device 1 shown in FIG. 1e, the first concentrator element 1.1 is inserted with a downstream part 1.1d thereof into the second concentrator element 1.2, which is in turn inserted with a downstream part 1.2d thereof inserted into a third concentrator element 1.3 which is identical with the first and second concentrator elements 1.1, 1.2. Thus, the second embodiment corresponds to the first embodiment, with the addition of the third concentrator element 1.3. The third concentrator element 1.3 comprises a third deflector with a third deflecting surface 31.3 and a third bypass opening 32.3. The concentrator elements 1.1, 1.2 and 1.3 are successively arranged in the intended flow direction 90f such that their axes 1.1a collide to form the axis 1a of the device 1. From the top views of cross-sections C-C of the concentrator elements 1.1, 1.2 in FIG. 1c, the third concentrator element 1.3 is angularly arranged correspondingly to the first concentrator element 1.1, so that the deflecting surface 31.3 thereof is angularly offset from the second deflecting surface 31.2 by an angle of approximately 180° around the axis 1a. Alike the arrangement of the first and second concentrator elements 1.1, 1.2, the downstream axial part 1.2d of the second concentrator element 1.2 is also arranged concentrically inside the successive third concentrator element 1.3.

[0199] The inlet element 1.1i of the first concentrator element 1.1 again forms the inlet element 10 of the device 1 according to the second embodiment. The outlet element of the third body element 1.3 forms the outlet element 20 of the device 1, and rectifies the flow of the particles 92 and the fluid 91 to follow parallel stream lines. In addition to the spacer element 40 between the inlets of the first and second concentrator element 1.1, 1.2, a spacer element 40 according to FIG. 1k is also arranged between the inlet elements of the second and third concentrator element 1.2, 1.3 so as to maintain an axial distance also between the inlets of these concentrator elements 1.2 and 1.3. As a result in the device 1, the radial distance between the deflecting surfaces 31.1 and 31.2, and between the deflecting surfaces 31.2 and 31.3, is at least five times the particle diameter of 1 mm. The axial length 40h of the spacer element 40 determines the axial length of both the first and second axial section 30.1, 30.2.

[0200] As shown in FIG. 1e, the first axial section 30.1 of the device 1 is formed only by an upstream part 1.1u of the first concentrator element 1.1 which protrudes above the second concentrator element 1.2. The intermediate, second axial section 30.2 is formed by the upstream axial part 1.2u of the second concentrator element 1.2 and part of the downstream axial part 1.1d of the preceding, first concentrator element 1.1. The third axial section 30.2 is formed by the third concentrator element 1.3, and additionally by the part of the downstream part 1.1d of the first concentrator element 1.1 and by the downstream part 1.2d of the second concentrator element 1.2.

[0201] As derivable from the top views of the cross-sections C-C in FIG. 1c of the concentrator elements 1.1, 1.2, 1.3, the deflecting surfaces 31.1, 31.2, 31.3 together extend over a majority of the angular range around the axis 1a—the respective angular zones 30α1, 30α2, 30α3 are diametrically opposite and together extend over around 350 degrees—alike in the first embodiment since the angular zones 30α1, and 30α3 are arranged to correspond to one another. Correspondingly, again the angular zones 30α1, 30α2, 30α3 over which the deflecting surfaces 31.1, 31.2, 31.3 of the three respective axial sections 30.1, 30.2, 30.3 extend, are smaller than the angular zones 30β1, 30β2, 30β3 over which the bypass openings 32.1, 32.2, 32.3 extend and the angular zones 30α1, 30α2, 30α3 are respectively completely inside the angular zones 30β2, 30β1, 30β2—wherein 30β1 corresponds to 30β3. Thus also in this embodiment the bypass openings 32.1, 32.2, 32.3 overlap over angular zones 32βo of around 5°, resulting in corresponding axial slits 32o of the device 1.

[0202] The remaining part 90r of the stream 90 is thus discharged from the device 1 through the bypass openings 32.1, 32.2, 32.3 partly via the annular spaces between the concentrator elements 1.1, 1.2, 1.3 and partly or directly or indirectly via angular slits 32o.

[0203] As explained in relation to the first embodiment the opening in the outlet elements 1.1o of the first and second concentrator element 1.1, 1.2 substantially prevent accumulation of particles 92 between the respective outlet element 1.1o and the respective deflecting surface 31.2, 31.3. The outlet element 20 is again provided with the shape adapter element 21.

[0204] For the third embodiment, FIGS. 2a,b show, respectively in a front view and a top view of cross-section C-C, a first concentrator element 1.1 of the device 1, which comprises four deflectors, having four first deflecting surfaces 31.1, and four first bypass openings 32.1 of the device 1. The first concentrator element 1.1 comprises an inlet element 1.1i, an axis 1.1a, and a outlet element 1.1o.

[0205] As is indicated in FIG. 2c, for forming the device 1 according to the third embodiment of the device 1 shown in FIGS. 2d-f, the first concentrator element 1.1 is inserted with a downstream part 1.1d thereof into a second concentrator element 1.2, which is in turn inserted with a downstream part thereof into a third concentrator element 1.3. The second and third concentrator elements 1.2, 1.3 are identical with the first concentrator element 1.1. The second concentrator element 1.2 comprises four second deflectors, having second directing surfaces 31.2, and four second bypass openings 32.2. The third concentrator element 1.3 comprises four third deflecting surfaces 31.3 and four third bypass openings 32.3. The concentrator elements 1.1, 1.2 and 1.3 are successively arranged in the intended flow direction 90f such that their axes 1.1a collide to form the axis 1a of the device 1. The second concentrator element 1.2 is angularly arranged with respect to the first concentrator element 1.1 such that the deflecting surfaces are angularly offset from one another by an angle 30αs of 45° around the axis 1a—see the top views of cross-sections C-C of the concentrator elements 1.1, 1.2, 1.3 in FIG. 2c and the top views of the device 1 in FIG. 2f. As may also be verified therefrom, the downstream axial parts of the first and second concentrator elements 1.1, 1.2 are arranged concentrically inside the successive second and third concentrator elements 1.2, 1.3, respectively.

[0206] As with the first and second embodiment, also here the inlet element 1.1i of the first concentrator element 1.1 forms the inlet element 10 of the device 1. The outlet element of the third body element 1.3 forms the outlet element 20 of the device 1. The outlet element 20 of the device 1 defining a cylindrical internal space over an axial length 20h is provided for rectifying the flow of the particles 92 and the fluid 91 to follow parallel stream lines.

[0207] As shown in FIG. 2c the spacer element 40 is arranged between the inlet element 1.1i of the first concentrator element 1.1 and the inlet element of the second concentrator element 1.2 and between the inlet elements of the second and third concentrator elements 1.2, 1.3 for maintaining an axial distance between the inlet elements of the concentrator elements 1.1, 1.2, 1.3 such that in the device 1, the radial distance between the deflecting surfaces 31.1 and 31.2 is at least five times the particle diameter of 1 mm. As shown best in FIG. 2d the first axial section 30.1 of the device 1 is formed only by an upstream part 1.1u of the first concentrator element 1.1 which protrudes above the second concentrator element 1.2. The axial length 40h of the spacer element 40 determines the axial length of the first and second axial sections 30.1, 30.2. The intermediate second axial section 30.2 is formed by the second concentrator element 1.2, and additionally by part of the downstream part 1.1d of the first concentrator element 1.1. The third axial section 30.2 is formed by the third concentrator element 1.3, and additionally by part of the downstream part 1.1d of the first element 1.1 and the downstream part of the second body element 1.2.

[0208] As visible from the top views of the cross-sections C-C in FIG. 2c of the concentrator elements 1.1, 1.2 and from the top views of the cross-sections C-C and D-D of the device 1 in FIG. 1g, the deflecting surfaces 31.1, 31.2 together extend over a majority of the angular range around the central axis 1a—the respective angular zones 30α1 and 30α2 are diametrically opposite and together extend over around 340 degrees.

[0209] The angular zones 30α1, 30α2, 30α3 over which the deflecting surfaces 31.1, 31.2, 31.3 of the three respective axial sections 30.1, 30.2, 30.3 extend, are also in this embodiment smaller than the angular zones 30β1, 30β2, 30β3 over which the bypass openings 32.1, 32.2, 32.3 extend. Furthermore, the angular zones 30α1, 30α2, 30α3 are respectively completely inside the angular zones 30β2, 30β1, 30β2—wherein 30β1 corresponds to 30β3—so that the bypass openings 32.1, 32.2 overlap over angular zones 32βo of around 5°, resulting in corresponding axial slits 32o of the device 1.

[0210] In the third embodiment, the remaining part 90r of the stream 90 is thus discharged from the device 1 through the bypass openings 32.1, 32.2, 32.3, partly via the annular space between the concentrator elements 1.1, 1.2 and partly directly and indirectly via angular slits 32o.

[0211] The outlet elements 1.1o of the concentrator elements 1.1, 1.2, 1.3 are provided with multiple axially and tangentially bounded and angularly regularly spaced openings. The opening in the outlet element 1.1o of the first concentrator element 1.1 enables particles 92 between the outlet element 1.1o of the first concentrator element 1.1 and the second deflecting surfaces 31.2 of the second concentrator element 1.2, and between the outlet element of the second concentrator element 1.2 and the third deflecting surfaces 31.3 to move into the outlet element 20 of the device 1 such as to end up in the target stream part 90t, thereby substantially preventing accumulation of these particles 92 between the outlets of the first and second concentrator elements 1.1, 1.2 and the respective deflecting surfaces 31.2, 31.3.

[0212] The outlet element 20 of the device 1 is provided with the shape adapter element 21 enclosing the outlet element 20 for converting the cross-section 90ct of the target stream part 90t of the stream 90 from a substantially circular shape to a substantially square shape. The target part 90t is enabled to spread over the square shaped cross-section by means of the openings in the outlet element 20.

[0213] In the first, second, and third embodiment, the deflecting surfaces 31.1, 31.2, 31.3 of each one of the axial sections 30.1, 30.2, 30.3 are angularly movable relative to the deflecting surfaces 31.1, 31.2, 31.3 of the other ones of the axial sections 30.1, 30.2, 30.3 by an angularly displacing axial sections 30.1, 30.2, 30.3 relative to one another. This is achieved by angularly displacing the respective concentrator elements 1.1, 1.2, 1.3 relative to one another.

[0214] For example, in relation to the third embodiment, the deflecting surfaces 31.1, 31.2, 31.3 are angularly spaced by an angle 31αs of 45°. One or more of the concentrator elements 1.1, 1.2, 1.3 of the device 1 may be rotated around axis 1a relative to one or more other ones of the concentrator elements 1.1, 1.2, 1.3 such as to change one or more of the angular spacing angle(s) 31αs and one or more of the angle(s) of the angular zones 32βo over which the axial slits 32o extend. When the angular zones 32βo are increased by the rotating, the chance that particles 92 escape through the slits 32o is increased, so that a larger part of the particles 92 in the stream 90 will end up in the remaining part 90r of the stream 90, and a smaller part of the particles 92 in the target part 90t. Thus, the concentration difference of the particles 92 between the remaining part 90r and the target part 90t will be reduced, and therefore the extent of the concentrating effect of the device 1 towards the target part 90ct of the cross-section 90c of the stream 90. Vice versa, by decreasing the angular zones 32βo less particles 92 will escape through the slits 32o to end up in the remaining part 90r whereas more particles 92 will end up in the target part 90t, such as to increase the concentration difference between the stream parts 90r, 90t, and increase the effectiveness of the device 1. The same principle applies to the first and second embodiment.

[0215] The invention also relates to the concentrator element 1.1 shown in relation to either embodiment—even as variations derivable therefrom which are within the scope of the invention.

[0216] A fourth, constructionally simple embodiment is shown in FIGS. 3a-d. This embodiment has a body 30 with two axial sections 30.1, 30.2, each with one respective deflector, having a respective deflecting surface 31.1, 31.2, and one respective bypass opening 32.1, 32.2. The inlet element 10, outlet element 20 and shape converter 21 are the same as in the first three embodiments—evenas the mentioned dimensions 10di, 10do, 10c, 20di, 10h, 20di, 20h thereof. The axial length 30h of the body 30 is approximately 55 mm. The angular zone 30α1 over which the first deflecting surface 31.1 extends is slightly larger than 1800 and the angular zone over which the second deflecting surface 31.2 extend is smaller than 180°. Together they again extend over the majority of the 360° angular range around the central axis 1a, namely over around 350°. The angular zones 30β1 and 30β2 over which the openings 32.1, 32.2 extend overlap over the angular zone 30βo.

[0217] Eventually, e.g. to enhance or reduce the concentrating effect, this embodiment may also be used as a single concentrator element, into which other, e.g. identical, concentrator elements are inserted in the way shown for the first three embodiments to form another embodiment of the device 1.

[0218] The device 1 according to either embodiment may be used in a method according to the invention as described herein.

[0219] Other embodiments of the device 1 may be envisaged from the figures—e.g. with more or less concentrator elements, more or less, or differently dimensioned or mutually spaced deflecting surfaces and bypass openings per axial section, non-concentric or (rotationally) non-symmetric arrangements of the concentrator elements, an axis not parallel to, but at an angle with the flow direction, etc., which suit the intended purpose and stream properties.

[0220] As mentioned, in FIGS. 4a-c a use of the first embodiment is shown being arranged inside a tube 80, and connected therewith at the inlet. Therein the particles 92 are sphere-shaped abrasive particles 92 with a diameter of approximately 1 mm, and the fluid is drilling fluid 91. The six example particles 92.1, 92.2, 92.3, 92.4, 92.5, 92.6 with exaggerated size illustrate how particles may end up either in the remaining part 90r of the stream 90 or the target part 90t. These examples do not represent an average of the behavior of the gross of the particles 92 in the stream 90—and are only shown for illustration of a few possibilities. It is shown that the target part 90t and remaining part 90r are discharged to continue downstream of the device and inside the tube 80 as a stream composed of the target part 90t and remaining part 90r, wherein the remaining part 90r encircles the target part 90t.

[0221] Because of their large Stokes number in the drilling fluid 91, the movement of the particles 92 is dominated by their inertia, though still influenced by the stream lines of the stream 90.

[0222] Particle 92.1 is by the impact with the first deflecting surface 31.1 in the first axial section 30.1 deflected inwardly towards the outlet element 1.1o of the first concentrator element 1 and bows off to the stream lines of the stream 90 to end up in the outlet element 20 of the device 1 and thus in the target portion 90t of the stream 90.

[0223] Particle 92.2 hits the first deflecting surface 31.1 quite far downstream in the downstream part 1.1d of the first concentrator element 1.1 in the second axial section 30.2 and happens to be redirected such that it passes the opening in the outlet element 1.1o of the first concentrator element 1.1 from the inside towards the annular space between the second deflecting surface 31.2 and consequently the outlet element 1.1o. By subsequently colliding with the second deflecting surface 31.2 at its downstream edge it is deflected via the annular space between the outlet element 1.1o and the second deflecting surface 31.2 into the remaining portion 90r of the stream 90.

[0224] Particle 92.3 is located halfway the radius of the stream 90 when entering the device 1 and is by a slight deflection due to a collision with another particle 92 pushed into an axial slit 300 to be discharged from the device 1 in the remaining portion 90r of the stream 90.

[0225] Particle 92.4 is deflected far downstream by impacting the second deflecting surface 31.2, such that it moves into outlet element 1.1o of the first concentrator element 1.1 via the bypass opening thereof, subsequently into the outlet element 20 of the device 1 where it moves through the lateral opening of the outlet element 20 against the wall of the shape converter 21, and is discharged from the device 1 in the target portion 90t of the stream 90—of which the cross-sectional shape is converted into a square by the shape converter 21 as shown.

[0226] Particle 92.5 is by the impact with the second deflecting surface 31.2 halfway the axial length of the device 1 in the second axial section 30.2 deflected inwardly towards the outlet element 1.10 of the first concentrator element 1 and bows off to the stream lines of the stream 90 to end up in the outlet element 20 of the device 1 and in the target portion 90t of the stream 90.

[0227] Particle 92.6 hits simultaneously another particle 92 and the second deflecting surface 31.2 at the corner of its upstream tangential edge with the inlet of the second concentrator element 1.2 and takes a sharp turn along the second deflecting surface 31.2 and through the second bypass opening 32.2 outwards from the first deflecting surface 31.1 to end up in the remaining portion 90r of the stream 90.

[0228] Of course, numerous other flow trajectories of the particles 92 are possible—the shown trajectories are only some special cases.

[0229] FIG. 5 illustrates the use of the device 1 in a sub 2 of an abrasive jet drilling system. Here, the device 1 is represented by simple contour lines only. FIG. 6a illustrates the sub 2 in a system 8 for abrasive jet drilling. The sub 2 is connected at a downhole end thereof via a recirculation sub 5 to a drill bit 3 of the system so as to be rotatable along therewith. At another end thereof the sub 2 is connected to a tubular drill string 4 of the system. The system is shown during a method of directional drilling of a curved borehole 6a in a subterranean earth formation 2. The drilling has progressed through limestone layer 7a and sandstone layer 7b into a rock layer 7c of the subterranean earth formation. The drill string 4 is rotated by top drive 9b of drilling tower 9a at the surface 7d. Within the cement casing of a main, vertical borehole 6, an anchor 3c is arranged and a whipstock 3d, which guides the drill string 4 through the casing to deviate into borehole 4a. Borehole 6a is the last of four curved boreholes 6a, 6b, 6c, 6d deviating from the main borehole 6 being drilled. All deviating curved boreholes 6a, 6b, 6c, 6d comprise a curved section and a subsequent straight section. The directional drilling system 8 is shown while deepening the straight section of borehole 6a. Borehole 6a has a borehole bottom 6a′.

[0230] At the surface 7d, besides the tower 9a and top drive 9b, a pump 98 is provided which pumps the drilling fluid 91 through a particle injection device 99. In particle injection device 99, abrasive particles 92 from an abrasive particles supply 95 are combined with the drilling fluid 91 to form the stream 90 of drilling fluid 91 mixed with abrasive particles 92. The stream 90 has a substantially constant flow rate and concentration of abrasive particles 92. The stream 90 is passed through a supply channel that runs through the drill string 4 into the system 8, inside which it runs subsequently through the steerable sub 4 and a recirculation sub 5 and drill bit 3. The drill bit 3 is in this case an abrasive jet drill bit. After passing the drill bit 3, the stream 90 impinges the borehole bottom 6a′ in the form of an abrasive jet of said stream 90, so as to erode the borehole bottom 6a′. After this impingement, the stream 90 progresses upwardly again towards the surface 7d, moving in between the annular space in between the cylindrical borehole wall and the system 8. While passing the recirculation sub 5, a portion of the abrasive particles 92 inside the stream 90 is captured from the annulus by the recirculation sub 5, and recirculated within the recirculation sub as a recirculation stream 93 to the stream 90. After the capture of the abrasive particles 92, the stream 90 progresses further towards the surface as return stream 94. The particles 92 still left in the recirculation stream 94 are filtered at the surface 7d to join the supply 95 of abrasive particles 92.

[0231] FIGS. 6b and 6c show, schematically, two possible embodiments of an abrasive jet drilling system 8. Both have the steerable sub 2, the interior of which is shown schematically in FIG. 6d in a magnification. In the system 8 of FIG. 6b, the drill bit 3 is a mechanical drill bit. In FIG. 6c, the drill bit 3 is an abrasive jet drill bit, and the system 8 comprises the recirculation unit 5. The mechanical drill bit comprises abrasive nozzle 3a, washer nozzle 3w, and cutters 3c. The abrasive jet drill bit comprises only an abrasive nozzle 3a.

[0232] The device 1 is shown provided in, and upstream of the drill bit 3 in the two respective, schematic, details in FIG. 6b, and is directed to the abrasive nozzle 3a so that the target part 90t of the stream 90 as received from the sub 2 via drill bit inlet 3i as discharged from the outlet 20 of the device 1 is directed into the abrasive jet nozzle 3a. When upstream of the drill bit 3, a hose catches the target stream with the high- and low concentration stream portions 90h, 901 from the outlet element 20 and guides it towards the abrasive jet nozzle 3a. Similarly, the device 1 may be provided upstream of, or in the abrasive jet drill bit, directing the target part 90t of the stream 90 as received from the recirculation sub 5 into the abrasive jet nozzle 3a thereof. This is shown in FIGS. 6e and 6f, also illustrating the alignment of the device with the borehole bottom section 6a″ which needs enhanced erosive power. The target part 90t of the stream 90 discharged by the outlet element 20 of the device 1 and containing the stream portions 90l, 90h is directed into the nozzle 3a in dependence of an azimuthal position of the nozzles such as to modulate the extent of erosion of a borehole bottom 6a′ along azimuthal positions thereof.

[0233] In FIG. 6d, the device 1 is shown being provided in the sub 2 of the system 8, upstream of a first channel ch1 inside a second channel ch2. The inlet 10 of the device 1 receives the stream 90 of drilling fluid 91 and abrasive particles 92 from the drill string 4. As depicted by FIGS. 5a-d, by alternately aligning and not aligning the first channel 1 with the outlet element 20 of the device 1, high concentration stream portions 90h and low concentration stream portions 90l are alternatingly created such that these are ejected by the nozzle 3a of the drill bit 3 when azimuthally within a section of the borehole bottom 6a′ which needs respectively enhanced or reduced erosive power—see FIG. 6e.

[0234] FIGS. 5a-d illustrate that the creation of the high and low concentration stream portions 10h and 10l is based on directing portions 90t.1, 90t.2, 90t.3, 90t.4, 90t.5, 90t.6, 90t.7, 90t.8 of the target part 90t discharged by the outlet element 20 of the device 1 alternatingly through the first channel ch1 and the second channel ch2, and portions 90r.1, 90r.2, 90r.3, 90r.4, 90r.6, 90r.7, 90r.8 of the remaining part 90r. Therein due to the larger cross-sectional area of the second channel ch2 relative to the first channel ch1 the target part portions 90t.4, 90t.6, 90t.8 move through the second channel ch2 at a larger velocity than the target part portions 90t.1, 90t.3, 90t.5, 90t.7, 90t.9 move through the first channel ch1. As a consequence the target part portions arrive together at the outlets of the channels ch1, ch2 to together combine to a high concentration stream portions 90h. As shown the target part portion 90t.1 combines with the target part portion 90t.4. Target part portion 90t.2 is here already downstream of 90t.1 and therefore not visible anymore. Similarly, the remaining part portions 90r.1, 90r.2, 90r.3, 90r.4, 90r.6, 90r.7, 90r.8 combine to low concentration stream portions 90l at the channel outlets. This principle of generating the high and low concentration stream portions for directional drilling is disclosed in NL2024001.

[0235] Here, the aligning and not aligning of the first channel ch1 is actuated by a linear motor 2m of the sub 2 pulling and releasing the inlet end of the channel ch1 via a connected cable 2c led over sheave 2cs, counteracted by spring 2s, such as to pivot the channel ch1 out of and into alignment with the outlet 20 of the device, respectively, around a pivot axis at the outlet end. FIGS. 5b and 5c illustrate alignment and non-alignment of the inlet of the first channel ch1 resulting from the pivoting.