WO2010101987A2

WO2010101987A2 - Two pipe horizontal directional drilling system

Info

Publication number: WO2010101987A2
Application number: PCT/US2010/026025
Authority: WO
Inventors: Robin W. Carlson; David Wisniewski
Original assignee: Vermeer Manufacturing Company
Priority date: 2009-03-03
Filing date: 2010-03-03
Publication date: 2010-09-10
Also published as: WO2010101987A3

Abstract

The present disclosure provides a drill drive unit and drill string make up and break up method for use with a dual pipe drill string configuration. The drill drive unit includes telescoping outer and inner drive shafts that are configured to rotate independent of each other. The method involves connecting and disconnecting inner shafts and outer shafts of the dual pipe drill string.

Description

TWO PIPE HORIZONTAL DIRECTIONAL DRILLING SYSTEM

This application is being filed on 3 March 2010, as a PCT

International Patent application in the name of Vermeer Manufacturing Company, a U.S. national corporation, applicant for the designation of all countries except the US, and Robin W. Carlson and David Wisniewski, citizens of the U.S., applicants for the designation of the US only, and claims priority to U.S. Provisional Patent Application Serial No. 61/157,042, filed March 3, 2009, which is incorporated by reference in its entirety herein.

Technical Field

The present disclosure provides an apparatus and method for directional drilling.

Background

Directional boring machine and methods for making underground holes are known. A typical directional boring machine is generally configured to drive into the ground a series of drill rods joined end-to-end to form a drill string.

At the end of the drill string is a rotating drilling tool. Typically, the rotation of the drill tool is driven by a mud motor or by axially rotating the drill string itself.

Various techniques and configurations can be used to provide steering of the drill string during boring operations. Improvements in directional boring machines, drill strings for use with such machines, and methods of directional drilling are needed.

Summary

Brief Description of the Figures

Figures IA-B are perspective views of an embodiment of a drilling machine according to the present disclosure; Figure 2 is a side view of a drill string drive assembly of the drilling machine of Figure 1;

Figures 3 A-C are perspective views of an embodiment of an inner member of a drill rod that is configured to be used with the drilling machine of Figure 1;

Figures 4A-C are perspective views of an embodiment of an outer member of a drill rod that is configured to be used with the drilling machine of Figure 1;

Figures 5A-C are perspective cross-sectional views of the assembled drill rod including the inner and outer members of Figures 3A-C and 4A-C;

Figures 6A-C are perspective cross-sectional views of the assembled drill rod including the inner and outer members of Figures 3A-C and 4A-C;

Figures 7A-B are views of a drive unit of the drilling machine of figure 1 wherein the inner and outer drive shafts are at different axial positions relative to each other;

Figures 8A-B are horizontal cross-sectional views of the drive unit of Figures 7A-B taken along cross-section lines 8A-8A and 8B-8B;

Figures 9A-B are vertical cross-sectional views of the drive unit of Figures 7A-B; Figure 10 is an assembly view of a portion of the drive unit of Figures

7A-B;

Figure 1 IA is a perspective view of a portion of the break out mechanism of the drilling machine of Figure 1;

Figure 1 IB is a top view of a break out mechanism of Figure 1 IA; Figure 11 C is a vertical cross-sectional view of the break out mechanism of Figure 1 IA taken along cross-section lines 1 IC-11C;

Figure 12A is a side view of the drilling machine of Figure 1 in add rod position 1;

Figure 12B is a top view of the drilling machine of Figure 1 in add rod position 1 ;

Figure 12C is a cross-sectional view of a portion of the drilling machine of Figure 1 in add rod position 1 taken along cross-section lines 12C-12C; Figure 13A is a side view of the drilling machine of Figure 1 in add rod position 2;

Figure 13B is a top view of the drilling machine of Figure 1 in add rod position 2; Figure 13C is a cross-sectional view of a portion of the drilling machine of Figure 1 in add rod position 2 taken along cross-section lines 13C-13C;

Figure 14A is a side view of the drilling machine of Figure 1 in add rod position 3;

Figure 14B is a top view of the drilling machine of Figure 1 in add rod position 3;

Figure 14C is a cross-sectional view of a portion of the drilling machine of Figure 1 in add rod position 3 taken along cross-section lines 14C-14C;

Figure 15A is a side view of the drilling machine of Figure 1 in add rod position 4; Figure 15B is a top view of the drilling machine of Figure 1 in add rod position 4;

Figure 15C is a cross-sectional view of a portion of the drilling machine of Figure 1 in add rod position 4 along lines 15C-15C;

Figure 16A is a side view of the drilling machine of Figure 1 in add rod position 5;

Figure 16B is a top view of the drilling machine of Figure 1 in add rod position 5;

Figure 16C is a cross-sectional view of a portion of the drilling machine of Figure 1 in add rod position 5 taken along cross-section lines 16C-16C; Figure 17A is a side view of the drilling machine of Figure 1 in remove rod position 1 ;

Figure 17B is a top view of the drilling machine of Figure 1 in remove rod position 1;

Figure 17C is a cross-sectional view of a portion of the drilling machine of Figure 1 in remove rod position 1 taken along cross-section lines 17C- 17C;

Figure 18A is a side view of the drilling machine of Figure 1 in remove rod position 2; Figure 18B is a top view of the drilling machine of Figure 1 in remove rod position 2;

Figure 18C is a cross-sectional view of a portion of the drilling machine of Figure 1 in remove rod position 2 taken along cross-section lines 18C- 18C;

Figures 19A-C are views of engagement of the drilling machine with a rod in remove rod position 2;

Figure 2OA is a side view of the drilling machine of Figure 1 in remove rod position 3; Figure 2OB is a top view of the drilling machine of Figure 1 in remove rod position 3;

Figure 2OC is a cross-sectional view of a portion of the drilling machine of Figure 1 in remove rod position 3 taken along cross-section lines 20C- 2OC; Figure 21 A is a side view of the drilling machine of figure 1 in remove rod position 4;

Figure 21B is a top view of the drilling machine of Figure 1 in remove rod position 4;

Figure 21 C is a cross-sectional view of a portion of the drilling machine of Figure 1 in remove rod position 4 taken along cross-section lines 21C- 21C;

Figure 22A is a side view of the drilling machine of figure 1 in remove rod position 5;

Figure 22B is a top view of the drilling machine of figure 1 in remove rod position 5;

Figure 22C is a cross-sectional view of a portion of the drilling machine of Figure 1 in remove rod position 5 taken along cross-section lines 22C- 22C; and

Figure 23 is a side view of the drill tool configured to be used with the drilling machine of Figure 1. Detailed Description

Referring to Figures IA-B, a directional drilling machine 10 according to an embodiment of the present disclosure is schematically shown. The directional drilling machine 10 includes a chassis 12, which in some embodiments is movably supported on wheels or tracks 13. The chassis 12 supports a drill string drive assembly 14 and drill rod loading assembly 22. In the depicted embodiment the down hole end of the chassis 12 is connected to an anchoring mechanism 130 that secures the chassis to the ground. In the depicted embodiment the anchoring mechanism is shown as a pair of stake downs 132, 134. The drill string drive assembly 14 is configured to rotate the drill string 24 and push and pull drill string 24 about a drill axis 15. The angle of the drill string drive assembly 14 relative to the ground surface can be adjusted via controlling a tilt mechanism 17 (e.g., hydraulic cylinder). In other words, the tilt control mechanism 17 can be used to control the vertical orientation of the drill string 24 as it is introduced into the ground. The drill rod loading assembly 22 is configured to transport broken out drill rods 25 between the drill string drive assembly 14 and the drill rod storage unit.

In the depicted embodiment the drill rod loading assembly 22 is shown as a rod box configured to store the drill rods 25 in multiple vertical columns 23. A pair of load arms 19, 21 are provided at the lower end of the box for moving drill rods 25 from the rod box into alignment with the drill axis 15 during the drill string 24 insertion process (also referred to herein as rod add process) and from alignment with the drill axis 15 back to the rod box during the drill string 24 withdraw process (also referred to herein as the rod break out process or rod removal process).

Referring to figure 2, the drill string drive assembly 14 of the depicted embodiment includes a drive unit 16, a frame assembly 18, and a break out mechanism 20. The drill string drive unit 16 is configured to be driven towards the break out mechanism 20 to push a section of the drill string 24 into the ground, and be driven away from the break out mechanism 20 to pull a section of the drill string 24 from the ground. During the pushing and the pulling, the drill unit 16 can also rotate the drill string 24 about its longitudinal axis. In the depicted embodiment, the drill string drive assembly 14 includes a carriage 136 that engages a rack 138 on the frame 18. The carriage 136 supports the drive unit 16 and moves the drive unit 16 in an axial direction relative to the frame 18. In the depicted embodiment the carriage 136 includes two hydraulic motors 104, 103 that drive the movement of the carriage 136 along the rack 138. The break out mechanism 20 is configured to hold the drill string 24 in place while sections of the drill string (drill rods 25) are added or removed. In the drill rod adding process, the break out mechanism 20 secures the upper end of the drill string 24 while the drill rod loading assembly 22 aligns the drill rod 25 that is to be added to the drill string 24 with the upper end of the drill string 24 and drive unit 16. Once the lower end of the newly added rod 25 is secured to the upper end of the drill string, the break out mechanism 20 releases the drill string 24, allowing the drive unit to rotate and push the drill string 24 further into the ground.

In the drill rod removal process, the break out mechanism 20 secures the upper end of the drill string 24 while the drill rod that is to be removed is broken free from the drill string 24 and transported out of alignment from the drill string 24 by the drill rod loading assembly 22. Once the rod is removed, the drive unit 16 moves down to the upper end of the drill string 24 and is connected thereto. The break out mechanism 20 then releases the end of the drill string 24, allowing the drive unit to rotate and pull the drill string 24 further out of the ground. Referring to Figures 3-6, the drill string 24 is described in greater detail. In the depicted embodiment, the drill string 24 is comprised of a number of drill rods 25 connected to each other. In the depicted embodiment, each drill rod includes an inner member 26 (see Figure 3) and outer member 28 (see Figure 4). In the depicted embodiment, the inner members 26 are slidably received by the outer members 28 (see Figures 5 and 6).

In the depicted embodiment, both the inner and outer members 26, 28 can be rotated independent of each other. The inner members of the drill string 24 are collectively used to drive the rotation of the drill bit 39, while the outer members of the drill string are collectively used to simultaneously steer the drill string 24. The depicted configuration avoids the need to stop or slow the forward drilling to steer the drill string 24, which is typical of systems wherein the drill bit 39 is driven by the rotation of the drill string itself. The depicted configuration also avoids the need to use a mud motor to rotate the drill bit 39, which can result in an improved machine and drilling method.

In the depicted embodiment, the inner members 26 are connected to each other and to the drive unit 16 via a threaded connection. Each inner member includes one male end 27 and one female end 29, wherein the male and female ends are configured to be secured to the opposed end of an identically configured inner member 26. In the depicted embodiments the ends 27, 29 are threaded. The threaded connection between the inner members allows rotational force (torque) applied to one inner member 26 to be transferred to another inner member 26. The threaded connection between the inner members also allows axial thrust and tension forces (pushing and pulling forces applied by the drive unit 16) to be transferred from one inner member to another inner member 26.

In the depicted embodiment, the first end 31 of the outer member 28 is configured to interlock with the second end 33 of an identical outer member 28, and the second end 33 of the outer member 28 is configured to interlock with the first end 31 of an identical outer member 28. The depicted interlocking connection allows for transfer of torque from one outer member 28 to another outer member. The depicted interlocking connection also allows for transfer of axial thrust force from one outer member 28 to another. On the other hand, the interlocking connection does not allow for tension force (pulling force) to be transferred from one outer member 28 to another. In the depicted embodiment, the first end 31 includes tabs 35 that axially extend into recess 37 on the second end 33. In the depicted embodiment the first ends and second ends are castellated in that they have resemblance to the crenellated parapet of a medieval castle. In the depicted embodiment, the first ends and second ends also include conical guide members 144 that facilitate smooth engagement between ends of the outer members 28. In other words, the guide members 144 enable the outer members 28 to engage each other even if they are slightly misaligned.

In the depicted embodiment the diameter D2 of the ends of the inner member 26 is greater than the diameter D 1 of the middle portion of the inner members 26. The outer members 28 include inner projections 122 that extend towards the inner member 26 between the ends of the inner members 26 to keep the inner members 26 inside the outer members 28 even if the drill rod 25 is positioned such that the inner member 26 would otherwise slide out of the outer member 28. The diameter of the outer member 28 between the inner projections is D3 and the diameter of the outer member along the major portion of its length is D4. In the depicted embodiment D4 > D2 > D3 > Dl. In the depicted embodiment the ends of inner member 26 can slide out of the outer member 28, but the inner member is prevented from sliding completely out of the outer member. In the depicted embodiment between 1/2-10 feet of the inner member can be extended out of the outer member 28. In a more preferred embodiment between 1 to 4 feet of the inner member can be extended out of the outer members. Referring to figures 7A- 10, the drive unit 16 of the drill string drive assembly 14 is described in greater detail. The drill string drive unit 16 is configured to be able to drive the rotation of the inner members 26 and outer members 28 independently. The outer members 28 of the drill string 24 can be held stationary, rotated clockwise, or counterclockwise while the inner members 26 of the drill string 24 continue to drive the drill bit 39. The drive unit 16 is configured to connect to both the inner and outer members while accounting for the aggregated tolerance variations in between multiple inner members and multiple outer members. For example, although mean length of the inner members 26 and outer members 28 may be 10.0 feet long, it is possible that each inner member 26 in a twelve rod long drill string is 9 feet 11 % inches long, while each of the outer members 28 in a drill string is 10 feet ¹A inch long, resulting in the inner members and outer members being six inches offset.

Referring to figures 7A-10, drive unit 16 is shown in two positions. Figures 7A, 8A, and 9A show the outer drive 32 extended relative to the inner drive 30, and figures 7B, 8B, and 9B show the outer drive 32 retracted relative to the inner drive 30. The position of the inner drive 30 relative to the outer drive 32 is changed based on the exact lengths of the inner members 26 and outer members 28 of the drill rods that are in the drill string 24.

In the depicted embodiment the drive unit 16 includes at least one hydraulic motor that is configured to power the axial rotation of the inner and outer drives 30, 32. The depicted embodiment includes multiple hydraulic motors to power the movements of the drive unit 16. In the depicted embodiment two hydraulic motors 100, 101 drive the inner drive shaft 30, one hydraulic motor 102 drives the outer drive 32, and two hydraulic motors 103, 104 move the drive unit 16 along the frame assembly 18 (see FIGS. 12A-B).

In the depicted embodiment the inner drive 30 includes a proximal end 146 and distal end 148. The proximal end 146 is connected to a distal end 150 of a first drive shaft 34 (inner drive shaft) that drives the rotation of the inner members of the drill string. The proximal end 152 of the first drive shaft 34 engages gears that transmit torque from the motors.

The outer drive 32 includes a proximal end 154 and a distal end 156. The proximal end 154 includes a flange that is connected to a sleeve 36. In the depicted embodiment, the sleeve 36 is positioned within a cylindrical member 38, which can be retracted and extended by actuating a cylinder 40, 41 that is connected thereto. The rotation of the sleeve 36 is driven by a second drive shaft 42 (outer drive shaft) which is coaxially arranged with the first drive shaft 34. In the depicted embodiment, the sleeve 36 is configured to rotate while the cylindrical member 38 does not rotate.

In the depicted embodiment the outer surface of the second drive shaft 42 engages the inner surface of the sleeve 36 such that the sleeve can move axially relative to the drive shaft, but moves together with the second drive shaft 42 in the rotational direction about axis 15. Like the proximal ends of the first drive shaft 34, the proximal end 158 of the second drive shaft 42 engages gears that transmit torque from the motors. In the depicted embodiment first and second drive shafts can rotate independent of each other and the outer drive 32 is configured to move relative to the inner drive 30 in the axial direction.

Referring to figures 1 IA-B, the break out mechanism 20 of the drill string drive assembly 14 is described in greater detail. The break out mechanism includes a casing vise 106 for selectively securing the outer member 28 of a drill rod 25, an upper inner member vise 50 (also referred to as the upper vise), and a lower inner member vise 52 (also referred to as the lower vise) positioned between the upper inner member vise 50 and the casing vise 106. In the depicted embodiment the upper vise 50 includes a first cylinder 108 and a second cylinder 110. The first cylinder 108 provides a clamping force that can be exerted on the inner member 26 of a drill rod 25, while the second cylinder 110 enables the vise 50 to apply torque to the inner member 26 of a drill rod 25. In other words, the first cylinder 108 is configured to radially open and close the clamp jaws 160 of the vise 50, while the second cylinder 110 is configured to rotate the clamp jaws about axis 15.

Referring to figures 12A-16C, the sequence of adding a rod to the drill string is shown. Figures 12A-C depict the drive unit 16 and break out mechanism 20 in a first position where the drive unit 16 is near the break out mechanism 20 and the inner member 26 of the most recently added drill rod (referenced in the figures as 54) is secured by the lower vise 52. The drill rod 54 is structurally the same as drill rod 25, which is described above. This arrangement occurs after the most recently added drill rod 54 has been driven past the upper vise 50 of the break out mechanism 20. In the depicted embodiment the sleeve 36 of the drive unit 16 is retracted, and the inner drive shaft 30 further extends past the outer drive 32, and also past a portion of the upper vise 50. The inner drive shaft 30 is rotated to unthread itself from the inner member 26 of the most recently added drill rod 54, thereby axially freeing the inner drive unit 16 from the most recently added drill rod. During this step the outer member 28 of the most recently added drill rod 25 is secured in the casing vise 106.

Figures 13A-C depict the drive unit 16 and break out mechanism 20 in a second rod add position. In the second position the drive unit 16 is moved a distance away from the break out mechanism 20, to allow sufficient room between drive unit 16 and the break out mechanism 20 for receiving the next drill rod to be added to the drill string 24. In this position the inner member 26 of the most recently added drill rod 25 remains secured in the lower vise 52 of the break out mechanism 20. The second position is similar to the first position except that the drive unit 16 has been pulled away from the break out mechanism 20. The outer member 28 of the most recently added drill rod 25 remains secured in the casing vise 106.

Figures 14A-C depict the drive unit 16 and break out mechanism 20 in a third rod add position. In the third position the drive unit 16 remains at its same position as in the second rod add position described above. The next drill rod to be added to the drill string (referenced in the figures as 58) is shown aligned between the break out mechanism 20 and the drive unit 16. In the depicted embodiment the load arms 19, 21 move the drill rod 25 into alignment with the drill axis 15. The drill rod 58 is structurally the same as drill rod 25, which is described above. The down hole end 62 of the inner member 26 is brought into alignment with the upper vise 50 of the break out mechanism 20. In the depicted embodiment the upper vise 50 is not typically clamped onto the inner member during this step. The outer member 28 of the most recently added drill rod 25 remains secured in the casing vise 106.

Figures 15A-C depict the drive unit 16 and break out mechanism 20 in a fourth rod add position. In the fourth add rod position the drive unit 16 is brought into engagement with the up hole end of the inner member 26. The inner drive shaft 30 is axially rotated in a direction that threads the inner drive shaft 30 to the up hole end of the inner member. In the depicted embodiment the drill string can be driven down the hole during this step. In an alternative embodiment, where the upper vise is clamped during the third add rod position, the upper vise 50 would be released once the down hole end 60 of the inner member is threaded onto the up hole end 66 of the inner member of the most recently added drill rod (referenced in the figures as 54). The outer member 28 of the most recently added drill rod remains secured in the casing vise 106.

Figures 16A-C depict the drive unit 16 and break out mechanism 20 in a fifth (and final) rod add position. In the fifth position the outer sleeve member 36 of the drive unit 16 is extended and rotated until the outer drive 32 engages the up hole end 70 of the outer member of the drill rod 58, and the down hole end 72 of the outer member of the drill rod 58 engages the up hole end 74 of the outer member of the drill rod 54.

After the outer member 28 of the newly added drill rod 58 engages the outer member of the most recently added drill rod 54 the outer member 28 of the most recently added drill rod is released by the casing vise 106 and the drive unit 16 is ready to resume drilling. In other words, the drive unit 16 can begin rotating the drill bit by rotating the inner members of the drill string, steering the drill string by controlling the rotation of the outer members of the drill string, and simultaneously thrusting the newly added drill rod 58 into the ground. During drilling, the drive unit 16 applies torque and thrust to the outer members of the drill string. Once the desired hole is drilled via adding rods down the hole, the rod removal sequence is initiated. Referring to figures 17A-21C, the sequence of removing a rod from the drill string is shown. Figures 17A-C depict a first position in the rod removal sequence. In the depicted configuration the drill rod to be removed (referenced in the figures as 80) is pulled back by the drive unit 16. The drill rod 80 is structurally the same as drill rod 25, which is described above. In particular, as the drive unit 16 moves away from the break out mechanism 20 tension forces are transferred through the inner members of the drill string 24 to drag the drill string out of the hole. Because the inner and outer members of the drill string are both connected to the drilling head 112 (FIG. 23), the drilling head 112 is pulled by the inner members of the drill string, and in turn pushes the outer member of the drill string out of the hole. In the depicted embodiment, as the drive unit 16 moves away from the break out mechanism 20, compression forces exist in the outer members of the drill string and tension forces exist in the inner members of the drill string 24. In other embodiments the engagement between the inner and outer members of the drill rods transfers at least some of the pulling force from the inner members to the outer members. The drill rod to be removed 80 is retracted to a point where the up hole end 82 of the inner member of the drill rod next to the drill rod to be removed 80 is aligned with the lower vise 52 and the down hole end 86 of the inner member of the drill rod to be removed 80 is aligned with the upper vise 50. The outer member 28 of the next drill rod to be removed is secured in the casing vise 106.

Figures 18A-C depict a second position in the rod removal sequence. In the second rod removal position, the outer sleeve member 36 is rotated slightly and retracted, thereby causing the outer member 90 of the drill rod to be pulled in the up hole direction, thereby exposing the connection between the up hole end 82 of the inner member and the down hole end 86 of the inner member. Referring to figures 19A-C, the engagement between the outer member 28 of the rod to be removed 80 and the outer drive 32 is shown. In the depicted embodiment, rotating the outer drive 32 slightly in a clockwise direction engages the outer sleeve member 28 of the rod to be removed 80 such that the outer drive 32 can apply a pulling force to the outer member 28 of the rod to be removed. In the depicted embodiment, the recess 37 on the second end 33 of the outer member includes catches 116 that engage laterally extending tabs 114 on the ends of the outer drive 32. The engagement between the catches and the tabs 114 allows tension force to be applied by the outer drive 32 onto the outer member 28 of the rod to be removed. During this step the outer member 28 of the next drill rod to be removed remains secured in the casing vise 106. To allow the outer sleeve member 36 to retract during this step, both the lower vise 52 and the upper vise 50 are in their undamped orientations. Figures 20A-C depict a third position of the rod removal sequence.

In the third rod removal position the lower vise 52 secures the up hole end 86 of the inner member of the drill rod adjacent the drill rod to be removed 80, and the upper vise 50 secures the down hole end 86 of the inner member 26 of the drill rod to be removed 80. The second cylinder 110 is activated, enabling the vise 50 to apply torque to the inner member of the drill rod, thereby breaking the threaded connection between up hole end 82 of the inner member and the down hole end 86 of the inner member. The upper vise then releases the down hole end 86 of the inner member, and the inner drive shaft 30 is rotated to completely unthread the down hole end 86 of the inner member from the up hole end 82 of the inner member. During this step the outer member 28 of the next drill rod to be removed remains secured in the casing vise 106.

Figures 2 IA-C depict a fourth position of the rod removal sequence. In the fourth rod removal position the lower vise 52 continues to secure the up hole end 82 of the inner member of the drill rod that is adjacent the drill rod to be removed 80, and the upper vise 50 is again clamped down on the down hole end 86 of the inner member of the drill rod 80. The drive is rotated, thereby breaking the connection between the drive and the up hole end of the drill rod to be removed. This step disconnects the drive unit 16 from the drill string and the drill rod to be removed 80. During this step the outer member 28 of the next drill rod to be removed remains secured in the casing vise 106.

Figures 22A-C depict a fifth (and final) position of the rod removal sequence. In the fifth rod removal position the drill rod loading assembly 22 (FIGS. 1 and 2) transports the drill rod 80 from the drill string drive assembly 14 to a drill rod storage location (e.g., a rod box). In the depicted embodiment, the loading arms 19, 20 grab the drill rod and move into the rod box.

Referring to figure 23, a drill head 112 configured to be used with the drill of the present disclosure is shown. In the depicted embodiment the drill head 112 includes a distal end 118 and a proximal end 120. A drill bit 39 is attached to the distal end and the proximal end is attached to the end of the drill string 24. The drill bit 39 is driven by the rotation of the inner members of the drill string. The body of the drill head 112 includes a slight bend. The orientation of the body is determined by rotating the outer members of the drill string 24. To drill a straight path through consistent soil, the outer member is rotated at a constant rate.

However, to turn the drill string or maintain a particular path through inconsistent conditions, the outer members can be controlled accordingly. In the depicted embodiment, the rotational speed of the bit does not need to stop or slow down during steering operations. Also, mud motors are not needed to drive the bit, which eliminates the need for mud motor related components. It should be appreciated that in alternative embodiments, many other configurations are also possible. For example, some configurations may include mud motors.

The above specification, examples and data provide a complete description of the manufacture and use of the composition of the invention. Since many embodiments of the invention can be made without departing from the spirit and scope of the invention, the invention resides in the claims hereinafter appended.

Claims

WE CLAIM:

1. A directional drill comprising: a drill string drive assembly including a drive unit configured to move towards and away from a break out mechanism, wherein the drive unit includes an inner drive shaft and an outer drive shaft, wherein the inner and outer drive shafts are coaxially arranged and configured to rotate independent from each other, wherein the inner and outer drive shafts of the drive unit are configured to extend and retract relative to each other; and a drill rod loading assembly configured and arranged to load and unload drill rods from the drill string drive assembly.

2. The directional drill of claim 1, wherein the outer drive shaft is configured to move in the axial direction relative to a carriage of the drive unit.

3. The directional drill of claim 1, wherein the inner and outer drive shafts are configured so that in one orientation at least a portion of the inner drive shaft extends out from the outer drive shaft in a down hole direction.

4. The directional drill of claim 3, wherein the inner and outer drive shafts are configured so that in one orientation the entire inner drive shaft is positioned within the outer drive shaft.

5. The directional drill of claim 1 , wherein the outer drive shaft includes a distal end configured to be able to transfer torque, thrust, and tension to the drill string.

6. The directional drill of claim 1 , wherein the inner drive shaft includes a distal end configured to be able to transfer at least torque to the drill string.

7. The directional drill of claim 1 , wherein the break out mechanism comprises a third vise positioned adjacent a first and a second vise.

8. The directional drill of claim 1 , further comprising an engine, wherein the drill string drive assembly includes a plurality of hydraulic motors powered by the engine, wherein at least one motor drives the rotation of the inner drive shaft, at least one motor drives the rotation of the outer drive shaft, and at least one motor drives the drive unit towards and away from the break out mechanism.

9. A system for directional drilling comprising: a directional drill including a drive unit that is movable towards and away from a break out mechanism, wherein the drive unit includes an inner drive shaft and an outer drive shaft, wherein the inner and outer drive shafts are coaxially arranged and configured to rotate independent from each other, and wherein the inner drive shaft and the outer drive shaft are arranged and configured to extend and retract relative to each other; and a plurality of drill rods wherein each drill rod includes an inner member and an outer member, wherein the inner members are configured to be driven by the inner drive shaft and the outer members are configured to be driven by the outer drive shaft.

10. A method of directional drilling comprising: providing a drill string including a proximal end and a distal end, wherein the drill string includes a plurality of interconnected inner shaft members arranged within outer shaft members; providing a drill head connected to the distal end of the drill string, the drill head including a rotational drilling tool; driving the rotation of the rotational drilling tool with the rotation of the inner shaft members of the drill string; controlling the orientation of the drill head by controlling the position of the outer shaft members of the drill string; and wherein the drill string is configured such that separating two adjacent outer shaft members exposes the connection between two adjacent inner shaft members.

11. The method of claim 10, wherein the drill head includes an axial bend.

12. The method of claim 10, wherein the inner shaft member is rotated at a first speed and the outer shaft member is rotated at a second speed different that the first speed.

13. The method of claim 10, wherein the second speed is zero.

14. The method of claim 10, further comprising: providing a drill string drive including an inner drive shaft and an outer drive shaft; wherein each of the plurality of inner members of the drill string is coaxially arranged with one of the plurality of outer members into drill rods; adding a drill rod to the drill string by first connecting the inner drive shaft to an inner member of a drill rod to be added to the drill string, and connecting the inner member of the drill rod to be added to the drill string to an inner member of a drill rod that was last added to the drill string; and extending the outer drive shaft relative to the inner drive shaft to engage the outer drive shaft to the outer member of the drill rod to be added to the drill string, and engaging the outer member of the drill rod to an outer member of the last added drill rod to the drill string.

15. The method of claim 14, further comprising removing a drill rod by: first, retracting a drill rod to be removed until a down hole end of the drill rod to be removed is aligned with a vise assembly; second, detaching and retracting the outer members of the drill rod to be removed to expose the down hole end of the inner member of the drill rod to be removed and the up hole end of the inner member of the adjacent drill rod; and third, using the vise assembly to break the connection between the down hole end of the inner member of the drill rod to be removed and the up hole end of the inner member of the adjacent drill rod.

16. The method of claim 15, wherein portions of the vise assembly move longitudinally relative a rack.

17. A method of directional drilling comprising: providing a drill string drive including an inner drive shaft and an outer drive shaft; providing a plurality of drill rods each having an inner member and a coaxially arranged outer member; adding a drill rod to the drill string by: first connecting the inner drive shaft to an inner member of a drill rod to be added and connecting the inner member of the drill rod to be added to an inner member of a drill rod that was last added to the drill string; and second, extending the outer drive shaft relative to the inner drive shaft to engage the outer drive shaft to the outer member of the drill rod to be added, and to engage the outer member of the drill rod to an outer member of the last added drill rod.

18. The method of claim 17, further comprising removing a drill rod from the drill string by: first, retracting the inner drive shaft until a down hole end of a drill rod to be removed is aligned with a vise assembly; second, retracting the outer members of the drill rod to be removed to expose the down hole end of the inner member of the drill rod to be removed and the up hole end of the inner member of the adjacent drill rod; and third, securing the down hole end of the inner member of the drill rod to be removed in the vise assembly and securing the up hole end of the inner member of the adjacent drill rod in the vise assembly, and breaking the connection between the down hole end of the inner member of the drill rod to be removed and the up hole end of the inner member of the adjacent drill rod, and breaking the connection between the inner drive shaft and an up hole end of the drill rod to be removed.

19. The method of claim 17, wherein adding a drill rod to the drill string includes the step of moving the inner drive shaft and outer drive shaft relative to each other in an axial direction.