WO2015179906A1

WO2015179906A1 - Drill pipe rod for air rotary drilling

Info

Publication number: WO2015179906A1
Application number: PCT/AU2015/000327
Authority: WO
Inventors: Iann PITOUT
Original assignee: Driconeq Australia Pty Limited
Priority date: 2014-05-29
Filing date: 2015-05-29
Publication date: 2015-12-03

Abstract

The present invention relates to air rotary drilling systems, apparatus and methods, particularly air rotary drill pipes for use in air rotary drilling operations as well as methods of their use and assembly as well as parts thereof. The air rotary drill pipe, also known as reverse circulation and air core drill pipes, includes an outer pipe and an inner tube. The outer pipe has male and female tool joints. Each of the tool joints includes an axial passage and are coupled to opposite ends of the outer pipe. The inner tube includes an internal passage and has male and female inner tube ends coupled to opposite ends of the inner tube. The inner tube is positionable concentrically within the outer pipe to define an annulus therebetween. The male and female tool joints and the male and female inner tube ends are adapted for retaining the inner tube including the male and female inner tube ends coupled thereto in two opposite orientations relative to the outer pipe with the male and female tool joints coupled thereto. The invention also includes methods of assembly of the air rotary drill pipe and a drilling apparatus including a plurality of such air rotary drill pipes coupled end to end. Embodiments of the present invention can cater for various drill rig apparatus requiring different relative orientations of the outer pipe with male and female tool joints coupled thereto and the inner tube with male and female inner tube ends coupled thereto using the same stock of components.

Description

Drill Pipe Rod for Air Rotary Drilling

Technical Field

[0001] The present invention relates to air rotary drilling systems, apparatus and methods. The invention is related, particularly but not exclusively, to air rotary drill pipes for use in air rotary drilling operations as well as methods of their use and assembly as well as parts thereof.

Background of the Invention

[0002] Air rotary drilling employs drill rods including concentric inner and outer pipes, the inner pipe being positionable within the outer pipe to define an annulus between the inner and outer pipes. The inner pipe defines a central passage. A plurality of the drill pipes are connected together in end to end relation to form a drill string. Attached to the end of the drill string is either a rotary drill bit or percussion hammer with drill bit. The drill bit or hammer with drill bit and drill string are adapted to drill a hole upon the application of percussion and rotation forces to the drill string causing the drill bit to cut a hole. Compressed air is pumped down the drill string through the annulus between the inner and outer pipes. When the compressed air reaches the drill bit it picks up the cuttings and returns the cuttings to the surface via the central passage defined by the inner pipes, which are coupled end to end.

[0003] As can be appreciated, the central passage defined within the inner pipe is not in fluid communication with the annulus between the inner pipe and the outer pipe. Furthermore, the inner pipe must be supported within the outer pipe in position to maintain the annulus therebetween and to enable end to end coupling of consecutive drill rods and to provide fluid communication between the annuluses of consecutive drill rods to enable the compressed air to reach the drill bit at the end of the drill string. Furthermore, the inner pipes must also be configured to enable connection of end to end drill rods and to provide for fluid communication between the central passages of the inner pipes of the consecutive drill rods coupled together end to end.

[0004] Existing air rotary drill pipes, also known as reverse circulation and air core drill pipes, include an outer pipe and an inner tube. The outer pipe includes a male tool joint coupled to one end of the outer pipe and a female tool joint coupled to the other end of the outer pipe. The male tool joint is often referred to as a pin tool joint and for the purposes of describing the present invention such terms shall be considered interchangeable. Also, the female tool joint is often referred to as a box tool joint and for the purposes of describing the present invention such terms shall be considered interchangeable. A male inner tube end is coupled to one end of the inner tube and a female inner tube end is coupled to the other end of the inner tube.

[0005] In most such drill rig assembles, the female inner tube end coupled to the inner tube is orientated downwards into the hole and in such drill rig assembles the male inner tube end is orientated upwards. In some of these drill rig assemblies the male tool joint coupled to one end of the outer pipe can face downwards and be threadably connected to an upwardly facing female tool joint of an adjacent drill rod. In other drill rig assemblies, the male tool joint can face upwards and the female tool joint can face downwards.

[0006] In some less common drill rig assemblies, the female inner tube end is oriented upwards while the male inner tube end is oriented downwards. In such drill rig assembles, the male tool joint can face downwards and be threadably connected to an upwardly facing female tool joint of an adjacent drill rod, or vice versa. Rotation and percussion forces are primarily transferred through the outer pipes and through the male and female tool joints coupled to opposite ends of the outer pipe.

[0007] As can be appreciated, there are different drill rig apparatus that require a variety of orientations of the tool joints and of the inner tube ends. Existing drill rods for such different drilling apparatus require male and female tool joints that are specific to each configuration as well as male and female inner tubes ends that are specific to each configuration. Thus, to cater for each of the various drill rig apparatus, it is necessary to manufacture and stock two different male tool joints, one capable of receiving a female inner tube end and another capable of receiving a male inner tube end therewithin. Conversely, it is also necessary to manufacture and stock two different female tool joints, one capable of receiving a female inner tube end and another capable of receiving a male inner tube end therewithin. [0008] The above discussion of background art is included to explain the context of the present invention. It is not to be taken as an admission that any of the documents or other material referred to was published, known or part of the common general knowledge in Australia at the priority date of any one of the claims of this specification.

Summary of Invention

[0009] Accordingly, in one aspect, the present invention provides a drill pipe for air rotary drilling, the drill pipe including: an outer pipe having male and female tool joints, each tool joint including an axial passage and being coupled to opposite ends of the outer pipe,

an inner tube including an internal passage and having male and female inner tube ends coupled to opposite ends of the inner tube;

the inner tube being positionable concentrically within the outer pipe to define an annulus therebetween;

wherein the male and female tool joints and the male and female inner tube ends are adapted for retaining the inner tube including the male and female inner tube ends coupled thereto in each of two opposite orientations relative to the outer pipe with the male and female tool joints coupled thereto.

[0010] The male tool joint can sometimes be referred to as a pin tool joint and for the purposes of describing the present invention such terms shall be considered interchangeable. Also, the female tool joint can sometimes be referred to as a box tool joint and for the purposes of describing the present invention such terms shall be considered interchangeable.

[0011] The male and female tool joints can each include a shoulder extending radially inwardly within the axial passage for abutment with at least one of the male and female inner tube ends. Preferably, the abutment between the shoulder and the at least one of the male and female inner tube ends is in the axial direction.

[0012] Preferably, one of the male and female inner tube ends includes a radially outwardly extending shoulder for abutment in an axial direction with either of the male and female tool joints. Preferably, the other one of the male and female inner tube ends includes a fastener removably coupled thereto for abutment in the opposite axial direction with the other one of the male and female tool joints. The abutment between the male and female inner tube ends with the male and female tool joints in opposite axial directions restricts longitudinal movement of the inner tube relative to the outer pipe. Preferably, the abutment between the male and female inner tube ends with the male and female tool joints in opposite axial directions prevents any substantial longitudinal movement of the inner tube relative to the outer pipe.

[0013] The fastener can be in the form of a retaining ring that is releasably received within a groove of the other one of the male and female inner tube ends. In a preferred embodiment, the retaining ring is a circlip.

[0014] Preferably, one of the male and female inner tube ends includes a pair of opposite radially outwardly extending shoulders for abutment in opposite axial directions with either of the male and female tool joints. The abutment between the opposite radially outwardly extending shoulders of the male and female inner tube ends with the male and female tool joints in opposite axial directions restricts longitudinal movement of the inner tube relative to the outer pipe. Preferably, the radially outwardly extending shoulders are received within the male or the female tool joint through an interfering section into a slot formed within the male or the female tool joint.

[0015] One or both of the male and female tool joints can include a plurality of ridges extending inwardly from a circumference of the axial passage. The ridges abut each of the male and female inner tube ends, preferably in the radial direction, to position the inner tube concentrically within the outer pipe to define the annulus therebetween. The ridges are separated by troughs for providing fluid communication between the annuluses of consecutive drill pipes.

[0016] The male and female tool joints can include complementary threads for threaded connection therebetween.

[0017] The male inner tube end is received within the female inner tube end for providing fluid communication between the internal passages of consecutive inner tubes of consecutive drill pipes. [0018] In another aspect, the present invention provides an air rotary drilling apparatus. The apparatus includes a plurality of drill pipes in accordance with the aspect of the invention, and any one of the embodiments thereof, described above.

[0019] In an embodiment, the plurality of drill pipes are coupled end to end and can be mounted to a drill rig wherein the male tool joints are oriented downwards and the female tool joints are oriented upwards, and the male inner tube ends are selectively oriented downwards or upwards and the female inner tube ends are oriented in the opposite direction to the selected orientation of the male inner tube ends.

[0020] In another embodiment, the plurality of drill pipes are coupled end to end and can be mounted to a drill rig wherein the male tool joints are oriented upwards and the female tool joints are oriented downwards, and the male inner tube ends are selectively oriented downwards or upwards and the female inner tube ends are oriented in the opposite direction to the selected orientation of the male inner tube ends.

[0021] In another aspect, the present invention provides male and female tool joints for an air rotary drill pipe. Each male and female tool joint includes a body defining an axial passage for coupling to an end of an outer pipe of an air rotary drill pipe. A shoulder extends radially inwardly from a circumference of the axial passage for abutment, preferably in the axial direction, with a male or a female inner tube end coupled to an end of an inner tube of an air rotary drill pipe. When coupled to the ends of the outer pipe the male and female tool joints are adapted for retaining the inner tube including the male and female inner tube ends coupled thereto in each of two opposite orientations relative to the outer pipe with the male and female tool joints coupled thereto.

[0022] In an embodiment, a plurality of ridges extend inwardly from the circumference of the axial passage. The ridges are adapted for abutting, preferably in the radial direction, with a male or female inner tube end to position the inner tube end concentrically within the tool joint to define the annulus between an inner tube and an outer pipe. The ridges are separated by troughs for providing fluid communication between the annuluses of consecutive drill pipes. [0023] The male and female tool joints can include complementary threads for threaded connection therebetween.

[0024] In another aspect, the present invention provides a method of assembling an air rotary drill pipe. The method includes: providing an outer pipe including an axial passage and coupling male and female tool joints to opposite ends of the outer pipe;

providing an inner tube including an internal passage and coupling male and female inner tube ends to opposite ends of the inner tube; and selectively positioning the inner tube including the male and female inner tube ends coupled thereto in either one of two opposite axial orientations concentrically within the outer pipe including the male and female tool joints coupled thereto wherein in the first axial orientation the male inner tube end is within the male tool joint and the female inner tube end is within the female tool joint and in the second axial orientation the female inner tube end is within the male tool joint and the male inner tube end is within the female tool joint.

[0025] In some embodiments, the method includes providing each of the male and female tool joints with a shoulder extending radially inwardly within the axial passage and positioning one of the male and female inner tube ends in abutment in an axial direction with the shoulder of one of the male and female tool joints.

[0026] The method can include providing one of the male and female inner tube ends including a radially outwardly extending shoulder for abutment in the axial direction with the shoulder of the one of the male and female tool joints, and removably coupling a fastener to the other one of the male and female inner tube ends for abutment in the opposite axial direction with the other one of the male and female tool joints, for restricting longitudinal movement of the inner tube relative to the outer pipe and preferably substantially preventing any such movement.

[0027] The method can include providing one or both of the male and female tool joints with a plurality of ridges extending inwardly from a circumference of the axial passage, abutting the ridges with at least one of the male and female inner tube ends to position the inner tube concentrically within the outer pipe and to define the annulus therebetween, and providing troughs between the ridges for providing fluid communication between the annuluses of consecutive drill pipes.

[0028] Selectively positioning the inner tube including the male and female inner tube ends coupled thereto in either one of two opposite orientations concentrically within the outer pipe including the male and female tool joints coupled thereto can include inserting the inner tube including the inner tube ends coupled thereto into one end of the outer tube including the tool joints coupled thereto and inserting a fastener into the male or female tool joint at the opposite end of the outer tube to retain the inner tube in a fixed longitudinal position relative to the outer pipe.

[0029] In another aspect, the present invention provides a method of assembling an air rotary drill apparatus comprising a plurality of drill pipes coupled end to end, the method including: providing a plurality of drill pipes each having an outer pipe including male and female tool joints coupled to opposite ends of the outer pipe and an inner tube including an internal passage and male and female inner tube ends coupled to opposite ends of the inner tube; selectively positioning the inner tube including the male and female inner tube ends coupled thereto in either one of two opposite axial orientations concentrically within the outer pipe including the male and female tool joints coupled thereto wherein in the first axial orientation the male inner tube end is within the male tool joint and the female inner tube end is within the female tool joint and in the second axial orientation the female inner tube end is within the male tool joint and the male inner tube end is within the female tool joint; and connecting the male tool joint and the male or the female inner tube end at an end of one of the drill pipes with the female tool joint and the other one of the male or the female inner tube ends at an end of another one of the drill pipes.

[0030] In embodiments, the method can include mounting the plurality of consecutive drill pipes to a drill rig wherein the male tool joints are oriented downwards and the female tool joints are oriented upwards, and the male inner tube ends are selectively oriented downwards or upwards and the female inner tube ends are oriented in the opposite direction to the selected orientation of the male inner tube ends.

[0031] In embodiments, the method can include mounting the plurality of consecutive drill pipes to a drill rig wherein the male tool joints are oriented upwards and the female tool joints are oriented downwards, and the male inner tube ends are selectively oriented downwards or upwards and the female inner tube ends are oriented in the opposite direction to the selected orientation of the male inner tube ends.

Brief Description of Drawings

[0032] The invention will now be described in detail with reference to embodiments of the invention illustrated in the accompanying drawings, wherein:

[0033] Figure 1 illustrates a perspective view of a longitudinal cross section of an embodiment of the invention including a drill pipe including an outer pipe including male and female tool joints coupled to ends thereof and an inner tube including inner tube ends coupled to ends thereof wherein the inner tube is positioned concentrically within the outer pipe to define an annulus therebetween and wherein the drill pipe is in the first of two possible configurations in which the inner pipe including male and female inner tube ends coupled thereto can be positioned within the outer pipe with male and female tool joints coupled thereto, and wherein the longitudinal cross section has been taken along the section line illustrated in Figure 5;

[0034] Figure 2 illustrates a perspective view of a longitudinal cross section of the embodiment of the drill pipe of Figure 1 , wherein the cross section has been taken along the section line illustrated in Figure 5 which is radially offset to the section line along which the cross section illustrated in Figure 1 is taken;

[0035] Figure 3 illustrates a perspective view of longitudinal cross section of the outer pipe of the embodiment of Figure 1 including the male and female tool joints coupled to ends thereof;

[0036] Figure 4 illustrates a perspective view of longitudinal cross section of the inner tube of the embodiment of Figure 1 including the inner tube ends coupled to ends thereof; [0037] Figure 5 illustrates an end view of an orthogonal cross section of the female tool joint including the male inner tube end therewithin, and also illustrates longitudinal section lines along which the cross sections of Figures 1 and 2 are taken;

[0038] Figure 6 illustrates a perspective view of longitudinal cross section of the female tool joint;

[0039] Figure 7 illustrates a perspective view of longitudinal cross section of the male tool joint;

[0040] Figure 8 illustrates a perspective view of longitudinal cross section of the male inner tube end;

[0041] Figure 9 illustrates a perspective view of longitudinal cross section of the female inner tube end;

[0042] Figure 10 illustrates a perspective view of a longitudinal cross section of the drill pipe of Figure 1 , wherein an outer pipe including male and female tool joints coupled to ends thereof and an inner tube including inner tube ends coupled to ends thereof, wherein the inner tube is positioned concentrically within the outer pipe to define an annulus therebetween, wherein the drill pipe is in the second of two possible configurations in which the inner pipe including male and female inner tube ends coupled thereto can be positioned within the outer pipe with male and female tool joints coupled thereto, and wherein the longitudinal cross section has been taken along the same section line illustrated in Figure 5 as Figure 1 ;

[0043] Figure 1 1 illustrates a perspective view of a longitudinal cross section of the embodiment of the drill pipe of Figure 10, wherein the cross section has been taken along the same section line illustrated in Figure 5 as Figure 2;

[0044] Figure 12 illustrates a perspective view of a longitudinal cross section of two like drill pipes mechanically coupled together, wherein the male tool joint contains the female inner tube end and the female tool joint contains the male inner tube end, wherein the cross section has been taken along the same section line illustrated in Figure 5 as Figure 2; [0045] Figure 13 illustrates a perspective view of a longitudinal cross section of two like drill pipes mechanically coupled together, wherein the female toll joint contains the female inner tube end and the male tool joint contains the male inner tube end, wherein the cross section has been taken along the same section line illustrated in Figure 5 as Figure 2;

[0046] Figure 14 illustrates a perspective view of longitudinal cross section of another embodiment of the inner tube and inner tube ends coupled thereto for use with the outer pipe including male and female tool joints coupled to ends thereof of of Figure 1 ;

[0047] Figure 15 illustrates an enlarged view of a portion of the drill pipe of Figure

14 illustrating, in more detail, the connection between the inner tube and the inner tube ends coupled to ends thereof;

[0048] Figure 16 illustrates a perspective view of a longitudinal cross section of an embodiment of the invention including a drill pipe including an outer pipe including male and female tool joints coupled to ends thereof and an inner tube including inner tube ends coupled to ends thereof wherein the inner tube is positioned concentrically within the outer pipe to define an annulus therebetween and wherein the drill pipe is in the first of two possible configurations in which the inner pipe including male and female inner tube ends coupled thereto can be positioned within the outer pipe with male and female tool joints coupled thereto;

[0049] Figure 17 illustrates an enlarged view of a portion of the drill pipe of Figure

15 illustrating, in more detail, a means of retaining the inner tube including inner tube ends coupled to ends thereof within the outer pipe including male and female tool joints coupled to ends thereof.

Detailed Description

[0050] Referring now to Figures 1 to 13, there is illustrated an embodiment of the invention in the form of a drill pipe 10 for air rotary drilling. The drill pipe 10 including an outer pipe 20 having an internal passage 21 , a first end 22 and a second end 24 opposite the first end 22. A male tool joint 30 (i.e. pin tool joint) is coupled to the first end 22 of the outer pipe 20 and a female tool joint 40 (i.e. box tool joint) is coupled to the second end 24 of the outer pipe 20. The male tool joint includes an axial passage 32 and the female tool joint also includes an axial passage 42. The drill pipe 10 also includes an inner tube 60 including an internal passage 61 , a first end 62 and a second end 64 opposite the first end 62. A female inner tube end 70 is coupled to the first end 62 and a male inner tube end 80 is coupled to the second end 64 of the inner tube 60. The inner tube 60 is positionable concentrically within the outer pipe 20 to define an annulus 2 therebetween. The male and female tool joints 30, 40 and the male and female inner tube ends 80, 70 are adapted for retaining the inner tube 60 including the male and female inner tube ends 80, 70 coupled thereto in each of two opposite orientations relative to the outer pipe 20 with male and female tool joints 30, 40 coupled thereto.

[0051] As will be appreciated from the foregoing detailed description, the invention provides for positioning the inner tube 60 including the male and female inner tube ends 80, 70 coupled thereto in either one of two opposite axial orientations concentrically within the outer pipe 20 including the male and female tool joints 30, 40 coupled thereto. In the first axial orientation the male inner tube end 80 is within the male tool joint 30 and the female inner tube end 70 is within the female tool joint 40. In the second axial orientation the female inner tube end 70 is within the male tool joint 30 and the male inner tube end 80 is within the female tool joint 40. In each drill pipe 10 of an air rotary drilling apparatus the male tool joint 30 may be oriented downwards or upwards and the female tool joint 40 may be oriented upwards or downwards depending on the drill rig with which the drill pipe 10 is to be used. Most drill rigs require the male inner tube end 80 to be oriented upwards and the female inner tube end 70 to be oriented downwards. However, there are some less common drill rigs requiring the female inner tube end 70 to be oriented upwards and the male inner tube end 80 to be oriented downwards.

[0052] Thus, the present invention is advantageous in that it provides for a single set of male and female tool joints 30, 40 and a single set of male and female inner tube ends 80, 70 that can, in use, be coupled to the outer pipe 20 and the inner tube 60 and be adapted to position the inner tube 60 concentrically within the outer pipe 20 to define an annulus 2 therebetween. The male inner tube end 80 can be selectively oriented upwards or downwards and the female inner tube end 70 oriented in the direction opposite to the male inner tube end 80 regardless of whether the male tool joint 30 is oriented upwards or downwards with the female tool joint 40 oriented in the direction opposite to the male tool joint 30. In other words, the present invention provides a single set of male and female tool joints 30, 40 and a single set of male and female inner tube ends 80, 70 that can, in use, be coupled to the outer pipe 20 and the inner tube 60 to form a drill pipe 10 having two configurations enabling the drill pipe 10 to be used each of the four types of drill rig apparatus arrangements described above, namely: 1 ) with the male inner tube end 80 oriented upwards, the female inner tube end 70 oriented downwards, the male tool joint 30 oriented upwards and the female tool joint 40 oriented downwards; or 2) with the male inner tube end 80 oriented upwards, the female inner tube end 70 oriented downwards, the male tool joint 30 oriented downwards and the female tool joint 40 oriented upwards; or 3) with the male inner tube end 80 oriented downwards, the female inner tube end 70 oriented upwards, the male tool joint 30 oriented upwards and the female tool joint 40 oriented downwards; or 4) with the male inner tube end 80 oriented downwards, the female inner tube end 70 oriented downwards, the male tool joint 30 oriented upwards and the female tool joint 40 oriented upwards.

[0053] Accordingly, the present invention is advantageous in that it provides drill rods 10 that have common male and female outer tool joints 30, 40 and common male and female inner tool ends 80, 70 that are suitable for configuring the drill rod 10 in each of the four possible configurations described above.

[0054] Preferably the male and female tool joints 30, 40 and the male and female inner tube ends 80, 70 are formed of hardened steel and are milled to the required diameter for the outer pipe 20 and the inner tube 60 with which they are to be used. Accordingly, the present invention is advantageous in that it means a smaller variety of male and female tool joints 30, 40 and male and female inner tube ends 80, 70 need to be produced and stocked for supply to users of the drill pipes 10 for air rotary drilling. This is because, the present invention enables a single set of male and female tool joints 30, 40 and male and female inner tube ends 80, 70 to be used with different types of drill rigs, of which some require the male inner tube ends 80 to be oriented upwards and the female inner tube ends 70 to be oriented downwards and others require the female inner tube ends 70 to be oriented upwards and the male inner tube ends 80 to be oriented downwards, wherein in all cases the male tool joint 30 is oriented downwards and the female tool joint 40 is oriented upwards. [0055] Referring to Figures 1 to 3, 7 and 10 to 13, the male tool joint 30 includes a first end 31 and a second end 35 opposite the first end 31 . The first end 31 of the male tool joint 30 is connected to the first end 22 of the outer pipe 20 and the second end 35 is for connection with a female tool joint 40 of another like drill pipe 10. A butt welded joint 23 is provided at the connection between the first end 31 of the male tool joint 30 and the first end 22 of the outer pipe 20. The axial passage 32 extends axially through the male tool joint 30 between the first end 31 and the second end 35. A shoulder 36 extends radially inwardly from a circumference 37 of the axial passage 32 for abutment with the male inner tube end 80 or the female inner tube end 70. Abutment between the shoulder 36 and the male or female inner tube ends 80, 70 is in the axial direction.

[0056] Referring to the figures 1 to 3, 6 and 10 to 13, the female tool joint 40 includes a first end 41 and a second end 35 opposite the first end 31 . The first end 41 of the female tool joint 40 is connected to the second end 24 of the outer pipe 20 and the second end 45 of the female tool joint 40 is for connection with a male tool joint 30 of another like drill pipe 10. A butt welded joint 25 is provided at the connection between the first end 41 of the female tool joint 40 and the second end 24 of the outer pipe 20. The axial passage 42 extends axially through the female tool joint 40 between the first end 41 and the second end 45. A shoulder 46 extends radially inwardly from a circumference 47 of the axial passage 42 for abutment with the male inner tube end 80 or the female inner tube end 70. Abutment between the shoulder 46 and the male or female inner tube ends 80, 70 is in the axial direction. Accordingly, both the male tool joint 30 and the female tool joint 40 include respective radially inwardly extending shoulders 36, 46 for abutment with either one of the male or female inner tube ends 80, 70 depending on the axial orientation of the inner tube 60 with the male and female inner tube ends 80, 70 coupled thereto within the outer pipe 20 with the male and female tool joints 30, 40 coupled thereto.

[0057] The male tool joint 30 includes a radially outwardly facing thread 38 that is adapted to threadably engage with a radially inwardly facing thread 48 of the female tool joint 40 to thereby mechanically couple adjacent drill pipes 10 together as illustrated in Figures 12 and 13 in particular. Each of the male tool joint 30 and the female tool joint 40 include respective outer recesses 39, 49 for engagement by a tool for tightening and loosening the threaded connection between adjacent pairs of the drill pipes 10.

[0058] As mentioned above, and as illustrated in Figures 1 , 2, 4 and 10 to 13, the inner tube 60 includes the internal passage 61 extending between the first end 62 and the second end 64. The female inner tube end 70 includes a first end 71 and a second end 75 opposite the first end 71 . The first end 71 of the female inner tube end 70 is connected to the first end 62 of the inner tube 60 and the second end 65 is for connection with a male inner tube end 80 of another like drill pipe 10. A butt welded joint 63 is provided at the connection between the first end 71 of the female inner tube end 70 and the first end 62 of the inner tube 60. A passage 72 extends axially through the female inner tube end 70 between the first end 71 and the second end 75. An annular groove is 78 is disposed in an internal wall 73 defining the passage 72. The annular groove 78 is adapted to receive a seal member 79 such as a urethane O-ring. The seal member 79 is adapted to provide a seal when the female inner tube end 70 is coupled to a male inner tube end 80 as described below. A shoulder 76 extends radially outwardly from a radially outwardly facing surface 77 and is adapted for abutment, in the axial direction, with the radially inwardly extending shoulder 36 of the male tool joint 30 or the radially inwardly extending shoulder 46 of the female tool joint 40. The second end 75 of the female inner tube end 70 has an internal diameter that is dimensioned to receive the male inner tube end 80 of another like drill pipe 10 therewithin.

[0059] The male inner tube end 80 includes a first end 81 and a second end 85 opposite the first end 81 . The first end 81 of the male inner tube end 80 is connected to the second end 64 of the inner tube 60 and the second end 85 of the male inner tube end 80 is for connection with the female inner tube end 70 of another like drill pipe 10. A butt welded joint 65 is provided at the connection between the first end 81 of the male inner tube end 80 and the second end 64 of the inner tube 60. A passage 82 extends axially through the male inner tube end 80 between the first end 81 and the second end 85. The male inner tube end 80 includes a radially outwardly facing groove 86 disposed about a radially outwardly facing surface 87. The groove 86 is adapted to receive a fastener 90, which in the embodiments illustrated in the Figure is a ring fastener or cir-clip. The fastener 90 is adapted to be releasably coupled to the male inner tube end 80 by being received in the groove 86. When coupled to the male inner tube end 80, the fastener 90 is adapted for abutment in the axial direction with the radially inwardly extending shoulder 36 of the male tool joint 30 or the radially inwardly extending shoulder 46 of the female tool joint 40.

[0060] As will be appreciated, depending on which axial orientation is chosen for the inner tube 60 with the male and female inner tube ends 70, 80 coupled thereto relative to the outer pipe 20 with the male and female tool joints 30, 40 coupled thereto the radially outwardly extending shoulder 76 of the female inner tube end 70 will abut with one of the radially inwardly extending shoulders 36, 46 of the male or the female tool joint 30, 40 and the fastener 90 releasably coupled to the male inner tube end 80 will abut in the axial direction with the other one of the radially inwardly extending shoulders 36, 46 of the male or the female tool joint 30, 40. A first axial orientation is illustrated in Figures 1 , 2 and 12, in which the male tool joint 30 contains the female inner tube end 70 and the female tool joint 40 contains the male inner tube end 80. A second axial orientation is illustrated in Figures 10, 1 1 and 13, in which the male tool joint 30 contains the male inner tube end 80 and the female tool joint 40 contains the female inner tube end 70.

[0061] The assembled drill pipe 10 is thereby adapted to provide for abutment between one of the male and female inner tube ends 70, 80, either by way of the radially outwardly extending shoulder 76 or the fastener 90 within the groove 86, with the male or the female tool joint 30, 40 in a first axial direction and for abutment between the other one of the male and female inner tube ends 70, 80, either by way of the radially outwardly extending shoulder 76 or the fastener 90 within the groove 86, with the other one of the male and the female tool joints 30, 40 in the opposite axial direction. Thus, longitudinal movement of the inner tube 60 relative to the outer pipe 20 is restrained and, preferably, substantially prevented. In other words, by each including radially inwardly extending shoulders 36, 46 the male and female tool joints 30, 40 are adapted to be engaged from opposite ends and in opposite directions by the male and female inner tube ends 70, 80 to axially lock the inner tube 60 relative to the outer pipe 20.

[0062] The male inner tube end 80 may be provided with a radially outwardly extending shoulder (not shown) instead of the recess 86 for receiving the fastener 90 and the female inner tube end 70 may be provided with a radially outwardly facing groove (not shown) extending about an outer circumferential surface to receive the fastener 90 instead of the shoulder 76. In any of the arrangements envisaged, the radially inwardly extending shoulder 36 of the male tool joint 30 and the radially inwardly extending shoulder 46 of the female tool joint 40 remain.

[0063] As mentioned above, the inner tube 60 is positionable concentrically within the outer pipe 20 to define an annulus 2 therebetween. The male tool joint 30 includes a plurality of ridges 33 extending inwardly from the circumference 37 of the axial passage 32. The ridges 33 are adapted to abut, in the radial direction, with the radially outwardly facing surface 77 of the female inner tube end 70 or the radially outwardly facing surface 77 of the female inner tube end 70. Similarly, the female tool joint 40 includes a plurality of ridges 43 extending inwardly from the circumference 47 of the axial passage 42. The ridges 43 are also adapted to abut, in the radial direction, the radially outwardly facing surface 77 of the female inner tube end 70 or the radially outwardly facing surface 77 of the female inner tube end 70. Thus, the ridges 33, 43 of the male and female tool joints 30, 40 are adapted to position the male and female inner tube ends 80, 70 and the inner tube 60 concentrically within the outer pipe 20 to define the annulus 2 between the inner tube 60 and the outer pipe 20.

[0064] The ridges 33, 43 of each of the male and female tool joints 30, 40 are separated by troughs 34, 44. In the embodiment illustrated in the Figures, the troughs 34, 44 are concave and semi-circular in profile. However, it is to be appreciated that the troughs may be formed with other concave profiles including, for example, a V- shaped provide. The troughs 34, 44 provide for fluid communication between the annuluses 2 of consecutive drill pipes 10 coupled together by way of the threaded engagement between the male and female tool joints 30, 40. Thus, air may be pumped through the annuluses 2 of consecutive drill pipes 10 in a drill string to the drill bit at the end of the drill string in a down-hole location The air may pick up cuttings produced by the bit at the down-hole location and return the cuttings to the surface through the internal passages 61 of consecutive inner tubes 60 coupled together by way of the female and male inner tube ends 70, 80. [0065] Assembling Drill Pipe and Drill String

[0066] Embodiments of a method of assembling the air rotary drill pipe 10 will now be described with reference to the Figures. The method including providing the outer pipe 20 and coupling the male and female tool joints 30, 40 to opposite ends 22, 24 of the outer pipe 20. Each of the male and female tool joints 30, 40 is provided with the respective axial passages 32, 42. The method also includes providing the inner tube 60, which includes the internal passage 61 and coupling the male and female inner tube ends 80, 70 to opposite ends 64, 62 of the inner tube 60.

[0067] The method further includes positioning the inner tube 60 including the male and female inner tube ends 80, 70 coupled thereto in either one of two opposite axial orientations concentrically within the outer pipe 20 including the male and female tool joints 30, 40 coupled thereto. In the first axial orientation the male inner tube end 80 is located within the male tool joint 30 and the female inner tube end 80 is within the female tool joint 40 and in the second axial orientation the female inner tube end 70 is within the male tool joint 30 and the male inner tube end 80 is within the female tool joint 40.

[0068] To position the inner tube 60 including the male and female inner tube ends 80, 70 coupled thereto in either one of the two opposite orientations concentrically within the outer pipe 20 including the male and female tool joints 30, 40 coupled thereto, the inner tube 60 including the inner tube ends 70, 80 coupled thereto is inserted into an end of the outer tube including the tool joints 30, 40 coupled thereto. In the embodiments illustrated in the Figures, the shoulder 76 extends radially outwardly from the radially outwardly facing surface 77 of the female inner tube end 70. Accordingly, the inner tube 60 including the inner tube ends 70, 80 coupled thereto is inserted male inner tube end 80 first (i.e. firstly inserting the inner tube end 70, 80 that does not include the radially outwardly facing shoulder) into the outer pipe 20 either first or second end 22, 24 first depending on which orientation of the inner tube 60 including the inner tube ends 70, 80 coupled thereto relative to the outer tube including the tool joints 30, 40 coupled thereto is required. When the inner tube 60 including the inner tube ends 70, 80 has been inserted completely within the outer tube 20 including the tool joints 30, 40 coupled thereto, the tool joints 30, 40 will contain within their axial passage 32, 42 the inner tube ends 70, 80. The shoulder 76 extending radially outwardly from the radially outwardly facing surface 77 of the female inner tube end 70 will axially abut against either the radially inwardly extending shoulder 36 of the male tool joint 30 or the radially inwardly extending shoulder 46 of the female tool joint 40. Also, the radially outwardly facing groove 86 extending about the radially outwardly facing surface 87 of the male inner tube end 80 will be positioned so as to receive the fastener 90, which in the embodiments illustrated in the Figure is a ring fastener or cir-clip that is inserted into whichever of the male and female tool joints 30, 40 contains the male inner tube end 80. The fastener 90, having been received within the groove 86, is adapted to axially abut with the radially inwardly extending shoulder 36, 46 of the one of the male and female tool joints 30, 40 containing the male inner tube end 80. Thus, the inner tube 60, including the male and female inner tube ends 70, 80 coupled thereto, is retained in a fixed longitudinal position relative to the outer pipe 20 and the male and female tool joints 30, 40 coupled thereto. As can be appreciated, the fastener 90, received within the groove 86 of the male inner tube end 80, and the radially outwardly extending shoulder 76 of the female inner tube end 70 abut with the radially inwardly extending shoulders 36, 46 of the male and female tool joints 30, 40 from axially opposite directions.

[0069] Thus, a distance between a second end 75 of the female inner tube end 70 from the second end 35 of the male tool joint 30, known as "female inner tube end 70 stand-off distance', is maintained substantially constant. Similarly, a distance between a second end 85 of the male inner tool end 80 from the second end 45 of the female tool joint 40, known as the 'male inner tube end 80 stand-off distance', is also maintained substantially constant. Thus, as illustrated in Figures 12 and 13, the male tool joint 30 of one drill pipe 10 can be inserted into the female tool joint 40 of an adjacent drill pipe 10 and the male inner tube end 80 can be received within the female inner tube end 70 by the precise amount, as determined by their respective stand-off distances, to ensure that as the threadable coupling between the male and female tools joints 30, 40 provided by the male and female threads 38, 48 is completed, an effective seal is provided between the male and female inner tool ends 80, 70. The seal member 79 provided in the annular groove 78 of the female inner tube end 70 is adapted to provide a seal with the radially outwardly facing surface 87 of the male inner tube end 80 when the female inner tube end 70 is coupled to a male inner tube end 80. [0070] By providing a plurality of the air rotary drill pipes 10 and coupling them consecutively in the aforementioned manner, a drill string can be formed for use with a drill rig apparatus The terminal rotary drill pipe 10 includes a bit coupled to the first end 22 thereof in place of the male tool joint 30. A compressed air pump is employed to pump compressed air into the annuluses 2 of the rotary drill pipes 10 of the drill string, which are in fluid communication by way of the grooves 34, 44 of the male and female tool joints 30, 40, to deliver the compressed air to the drill bit. Upon reaching the drill bit, the compressed air returns cuttings via the internal passages 61 of consecutive inner tubes 60 coupled together, in a substantially air tight manner, by way of the female and male inner tube ends 70, 80.

[0071] Figures 14 and 15 illustrate another embodiment of the outer pipe 120 and female tool joint 140 coupled to the first end 124 and the male tool joint 130 coupled to the second end 122 of the outer pipe 120. The outer pipe 120, the female tool joint 140 and the male tool joint 130 of Figures 14 and 15 differs from the embodiment of Figures 1 to 13 in the manner of connection or fixation therebetween. As can be seen in Figure 15 in particular, which illustrates an enlarged view of the first end 141 of the female tool joint 140 and the second end 124 of the outer pipe 120. The first end 141 of the female tool joint 140 is adapted to overlap an outwardly facing surface 124a of the second end 124 of the outer pipe 120. The first end 141 of the female tool joint 140 includes an inwardly facing surface 141 a that flares outwardly by gradually increasing in diameter. The outwardly facing surface 124a at the second end 124 of the outer pipe 120 tapers and gradually decreases in diameter. As such, the outwardly facing surface 124a at the second end 124 of the outer pipe 120 fits within the inwardly facing surface 141 a of the first end 141 of the female tool joint 140. The first end 141 of the female tool joint 140 terminates in a double bevelled edge with a tapered outwardly facing surface 141 b. Thus, a V-shaped void 101 is formed by the between the tapered outwardly facing surface 141 b of the first end 141 of the female tool joint 140 and the tapered outwardly facing surface 124a at the second end 124 of the outer pipe 120. The V-shaped void 101 allows for a partial or full penetration butt weld to be formed between the female tool joint 140 and the outer pipe 120. It is to be appreciated that a similar configuration of the second end 122 of the outer pipe 120 and the first end 131 of the male tool joint 130 also provides a V-shaped void 101 therebetween that allows for a partial or full penetration butt weld to be formed between the female tool joint 140 and the outer pipe 120. The embodiment illustrated in Figures 14 and 15 is advantageous in that eliminates the need for a portion of the tool joints 140, 130 to overlap on an inner surface of the outer pipe 120 at the connection therebetween thus minimising friction losses occurring within the internal passage 121 . Another advantage is that improved weld penetration can be achieved with complete fusion between the tool joints 140, 130 and the outer pipe 120. Also, the inwardly facing surface 141 a of the first end 141 of the female tool joint 140, and likewise the corresponding inwardly facing surface 131a of the male tool joint can be contoured to promote freedom of air flow within the internal passage 121 and within the tool joints 140, 130.

[0072] Figure 16 illustrates the outer pipe 120 and tool joints 140, 130 of Figures 14 and 15 and another embodiment of the inner tube 160 including an internal passage 161 , a first end 162 and a second end 164 opposite the first end 162. A female inner tube end 170 is coupled to the first end 162 and a male inner tube end 180 is coupled to the second end 164 of the inner tube 160. The inner tube 160 is positionable concentrically within the outer pipe 120 to define an annulus 102 therebetween. The male and female tool joints 130, 140 and the male and female inner tube ends 180, 170 differs from the embodiment of Figures 1 to 13 in that the plurality of ridges 143 extend radially outwardly from the circumference 187 of the male inner tube end 180 and likewise the plurality of ridges 133 extend radially outwardly from the circumference 177 of the female inner tube end 170. The ridges 143, 133 are adapted to abut, in the radial direction, the radially inwardly facing surface 147 of the female tool joint 140 and the radially inwardly facing surface 137 of the male tool joint 130. Thus, the ridges 133, 143 of the male and female inner tube ends 180, 170 are adapted to position the male and female inner tube ends 180, 170 and the inner tube 160 concentrically within the outer pipe 120 to define the annulus 102 between the inner tube 160 and the outer pipe 120. Also, the slots 144, 134 between the ridges 143, 133 provide for fluid communication between the annuluses 102 of consecutive drill pipes 1 10.

[0073] The radially inwardly facing surface 147 defining the axial passage 142 of the female tool joint 140 includes a tapering portion 147a extending from the second end 145 of the female tool joint 140. The tapering portion 147a tapers to a diameter slightly less than the diameter or circumference of the ridges 133, 143 of the male and female inner tube ends 180, 170 to form an interference section. The ridges 133, 143 of whichever of the female inner tube ends 180, 170 is to be received within the female tool joint 140 are forced through the interference section defined by the tapering portion 147a. As the ridges 133, 143 pass the interference section defined by the tapering portion 147a they reach a portion of the inwardly facing surface 147 of the female tool joint 140 defining a slot 147b having a diameter that is substantially equivalent to the diameter of the ridges 133, 143. Thus, the ridges 133, 143 are captured within the slot 147b to thereby restrict axial movement of the male and female inner tube ends 180, 170 and the inner tube 160 within the male and female tool joints 140, 130 and the outer pipe 120. Either or both of the ridges 133, 143 may include or incorporate an opposite pair of the shoulders 136a, 136b which, in the present embodiment, are adapted for abutment, by being captured within the slot 147b, in the axial direction with either the male or female tool joint 130, 140, or just the female tool joint 140 as in the present embodiment, in opposite axial directions to prevent any substantial longitudinal movement of the inner tube 160 relative to the outer pipe 120. Accordingly, the embodiment illustrated in Figures 14 to 17 does not require the fastener 90 as in the embodiment of Figures 1 to 13.

[0074] Those skilled in the art will appreciate that the invention described herein is susceptible to variations and modifications other than those specifically described. It is understood that the invention includes all such variations, modifications and mechanical equivalents which fall within the spirit and scope of the present invention.

[0075] Where the terms "comprise", "comprises", "comprised" or "comprising" are used in this specification (including the claims) they are to be interpreted as specifying the presence of the stated features, integers, steps or components, but not precluding the presence of one or more other feature, integer, step, component or group thereof.

Claims

Claims:

1. A drill pipe for air rotary drilling, the drill pipe including: an outer pipe having male and female tool joints, each tool joint including an axial passage and being coupled to opposite ends of the outer pipe;

wherein the male and female tool joints and the male and female inner tube ends are adapted for retaining the inner tube including the male and female inner tube ends coupled thereto in two opposite orientations relative to the outer pipe with the male and female tool joints coupled thereto.

2. The drill pipe of claim 1 , wherein the male and female tool joints each include a shoulder extending radially inwardly within the axial passage for abutment with at least one of the male and female inner tube ends.

3. The drill pipe of claim 1 or claim 2, wherein one of the male and female inner tube ends includes a radially outwardly extending shoulder for abutment in an axial direction with either of the male and female tool joints, a fastener removably coupled to the other one of the male and female inner tube ends for abutment in the opposite axial direction with the other one of the male and female tool joints, for restricting longitudinal movement of the inner tube relative to the outer pipe.

4. The drill pipe of claim 3, wherein the fastener is a retaining ring that is releasably received within a groove of the other one of the male and female inner tube ends.

5. The drill pipe of claim 1 or claim 2, wherein one of the male and female inner tube ends includes a pair of opposite radially outwardly extending shoulders for abutment in opposite axial directions with either of the male and female tool joints for restricting longitudinal movement of the inner tube relative to the outer pipe.

6. The drill pipe of claim 5, wherein the radially outwardly extending shoulders are received within the male or the female tool joint through an interfering section into a slot formed within the male or the female tool joint.

7. The drill pipe of any one of the preceding claims, wherein one or both of the male and female tool joints include a plurality of ridges extending inwardly from a circumference of the axial passage for abutting each of the male and female inner tube ends to position the inner tube concentrically within the outer pipe to define the annulus therebetween, the ridges being separated by troughs for providing fluid communication between the annuluses of consecutive drill pipes.

8. The drill pipe of any one of the preceding claims, wherein the male and female tool joints include complementary threads for threaded connection therebetween.

9. The drill pipe of any one of the preceding claims, wherein the male inner tube end is received within the female inner tube end for providing fluid communication between the internal passages of consecutive inner tubes.

10. An air rotary drilling apparatus including a plurality of the drill pipes of any one of the preceding claims, wherein the plurality of drill pipes are coupled end to end and are mounted to a drill rig wherein the male tool joints are oriented downwards and the female tool joints are oriented upwards, and the male inner tube ends are selectively oriented downwards or upwards and the female inner tube ends are oriented in the opposite direction to the selected orientation of the male inner tube ends.

1 1 . An air rotary drilling apparatus including a plurality of the drill pipes of any one claims 1 to 9, wherein the plurality of drill pipes are coupled end to end and are mounted to a drill rig wherein the male tool joints are oriented upwards and the female tool joints are oriented downwards, and the male inner tube ends are selectively oriented downwards or upwards and the female inner tube ends are oriented in the opposite direction to the selected orientation of the male inner tube ends.

12. Male and female tool joints for an air rotary drill pipe, each male and female tool joint including: a body defining an axial passage for coupling to an end of an outer pipe of an air rotary drill pipe; and a shoulder extending radially inwardly from a circumference of the axial passage for abutment with a male or a female inner tube end coupled to an end of an inner tube of an air rotary drill pipe; wherein when coupled to the ends of the outer pipe the male and female tool joints are adapted for retaining the inner tube including the male and female inner tube ends coupled thereto in two opposite orientations relative to the outer pipe with the male and female tool joints coupled thereto.

13. The tool joints of claim 12, including a plurality of ridges extending inwardly from the circumference of the axial passage for abutting a male or female inner tube end to position the inner tube end concentrically within the tool joint to define an annulus between the inner tube and the outer pipe, the ridges being separated by troughs for providing fluid communication between the annuluses of consecutive drill pipes.

14. The tool joints of claim 12 or claim 13, wherein the male and female tool joints include complementary threads for threaded connection therebetween.

15. A method of assembling an air rotary drill pipe, the method including: providing an outer pipe including an axial passage and coupling male and female tool joints to opposite ends of the outer pipe; providing an inner tube including an internal passage and coupling male and female inner tube ends to opposite ends of the inner tube; and selectively positioning the inner tube including the male and female inner tube ends coupled thereto in either one of two opposite axial orientations concentrically within the outer pipe including the male and female tool joints coupled thereto wherein in the first axial orientation the male inner tube end is within the male tool joint and the female inner tube end is within the female tool joint and in the second axial orientation the female inner tube end is within the male tool joint and the male inner tube end is within the female tool joint.

16. The method of claim 15, including: providing each of the male and female tool joints with a shoulder extending radially inwardly within the axial passage, and positioning one of the male and female inner tube ends in abutment in an axial direction with the shoulder of one of the male and female tool joints.

17. The method of claim 16, including: providing one of the male and female inner tube ends including a radially outwardly extending shoulder for abutment in the axial direction with the shoulder of the one of the male and female tool joints; and removably coupling a fastener to the other one of the male and female inner tube ends for abutment in the opposite axial direction with the other one of the male and female tool joints, for restricting longitudinal movement of the inner tube relative to the outer pipe.

18. The method of any one of claims 15 to 17, including: providing one or both of the male and female tool joints with a plurality of ridges extending inwardly from a circumference of the axial passage, abutting the ridges with at least one of the male and female inner tube ends to position the inner tube concentrically within the outer pipe and to define the annulus therebetween; and providing troughs between the ridges for providing fluid communication between the annuluses of consecutive drill pipes.

19. The method of any one of claims 15 to 18, wherein selectively positioning the inner tube including the male and female inner tube ends coupled thereto in either one of two opposite orientations concentrically within the outer pipe including the male and female tool joints coupled thereto includes: inserting the inner tube including the inner tube ends coupled thereto into one end of the outer tube including the tool joints coupled thereto and inserting a fastener into the male or female tool joint at the opposite end of the outer tube to restrict longitudinal movement of the inner tube relative to the outer pipe.

20. A method of assembling an air rotary drill apparatus comprising a plurality of drill pipes coupled end to end, the method including: providing a plurality of drill pipes each having an outer pipe including male and female tool joints coupled to opposite ends of the outer pipe and an inner tube including an internal passage and male and female inner tube ends coupled to opposite ends of the inner tube; selectively positioning the inner tube including the male and female inner tube ends coupled thereto in either one of two opposite axial orientations concentrically within the outer pipe including the male and female tool joints coupled thereto wherein in the first axial orientation the male inner tube end is within the male tool joint and the female inner tube end is within the female tool joint and in the second axial orientation the female inner tube end is within the male tool joint and the male inner tube end is within the female tool joint; and connecting the male tool joint and the male or the female inner tube end at an end of one of the drill pipes with the female tool joint and the other one of the male or the female inner tube ends at an end of another one of the drill pipes.

21 . The method of claim 20, including mounting the plurality of consecutive drill pipes to a drill rig wherein the male tool joints are oriented downwards and the female tool joints are oriented upwards, and the male inner tube ends are selectively oriented downwards or upwards and the female inner tube ends are oriented in the opposite direction to the selected orientation of the male inner tube ends.

The method of claim 20, including mounting the plurality of consecutive drill pipes to a drill rig wherein the male tool joints are oriented upwards and the female tool joints are oriented downwards, and the male inner tube ends are selectively oriented downwards or upwards and the female inner tube ends are oriented in the opposite direction to the selected orientation of the male inner tube ends.