Core tube displacer for long reach drilling machines

1. A long-reach drilling machine for exploration drilling and core sample collecting, comprising:

a drill string comprising a variable number of hollow drill rods and defining opposite first and second ends;

a drill bit installed at the first end of the drill string for cutting a bore hole through the ground and for cutting core samples out of the ground;

a ground-resting drill base for installation outside the borehole;

a mast attached to the drill base;

a drill head installed on and movable along the mast and to which the second end of the drill string is connected, the drill head rotating the drill string;

a core tube movable within the drill string between a first position at the drill string first end for receiving a core sample and a second position at the drill string second end;

an borehole core tube displacer capable of displacing the core tube between its first and second positions only; and

an external core tube displacer, distinct from the borehole core tube displacer, comprising a frame that is fixed relative to the drill string, a tube prehension device mounted to the frame and capable of traction on the core tube, and an actuator mounted to the frame and selectively actionable to activate the tube prehension device allowing the core tube to be displaced relative to the frame beyond its second position.

2. The long-reach drilling machine as defined in claim 1 , wherein the tube prehension device and the actuator allow movement of the core tube in two different directions relative to the drill string for respectively retrieving the core tube from the drill string when it is located at its second position, and for inserting the core tube into the drill string to position it at its second position.

3. The long-reach drilling machine as defined in claim 2 , wherein the prehension device includes rollers defining a tube channel therebetween that the core tube will engage, with the actuator acting on at least some of the rollers to rotate them.

4. The long-reach drilling machine as defined in claim 3 , wherein the rollers have outer surfaces provided with diamond fragments for providing a high friction coefficient between the outer surfaces and the core tube.

5. The long-reach drilling machine as defined in claim 4 , wherein the rollers are coated with a friction layer comprising the diamond fragments.

6. The long-reach drilling machine as defined in claim 3 , wherein at least some rollers are movable with respect to each other between an engaged position in which the at least some rollers are displaced towards the tube channel to grasp the core tube and allow its retrieval from and insertion into the drill string, and a disengaged position in which the at least some rollers are displaced away from the tube channel to release the core tube.

7. The long-reach drilling machine as defined in claim 1 , wherein the frame is attached to the drill head.

8. The A long-reach drilling machine as defined in claim 1 , wherein the frame is pivotally attached to one of the drill head, the drill base and the mast such that it is pivotable between an operative position in which it is pivoted towards a path of the core tube incoming or outgoing with respect to the drill string such that the core tube can engage the tube channel, and an inoperative position in which it is pivoted away from the path of the core tube incoming our outgoing with respect to the drill string such that the core tube cannot engage the tube channel.

9. The long-reach drilling machine as defined in claim 1 , wherein the borehole core tube displacer comprises at least one of a winch and a water pump.

10. A method of displacing a core tube with respect to a drill string of a long-reach drilling machine as defined in claim 1 , comprising:

engaging the core tube with the tube prehension device of the external core tube displacer; and

activating the prehension device of the external core tube displacer with the actuator to displace the core tube with respect to the drill string beyond its second positon.

11. The method as defined in claim 10 , wherein the step of activating the prehension device to displace the core tube with respect to the drill string beyond its second position is accomplished in a selected one of two directions for respectively retrieving the core tube from the drill string when it is at its second position, or for inserting the core tube into the drill string to position it at its second position.

12. The method as defined in claim 11 , wherein the prehension device includes rollers defining a tube channel therebetween, the step of engaging the core tube with the tube prehension device comprising engaging the core tube in the core tube channel, and the step of activating the prehension device with the actuator comprising the actuator acting on at least some of the rollers to rotate them.

13. The method as defined in claim 12 , wherein at least some rollers are movable with respect to each other between an engaged position in which the at least some rollers are displaced towards the tube channel to grasp the core tube and allow its retrieval from and insertion into the drill string, and a disengaged position in which the at least some rollers are displaced away from the channel to release the core tube, the step of engaging the core tube with the tube prehension device comprising displacing the at least some rollers towards the tube channel.

14. The method as defined in claim 10 , wherein the frame is pivotally attached to one of the drill head, the drill base and the mast such that it is pivotable between an operative position in which it is pivoted towards a path of the core tube incoming or outgoing with respect to the drill string such that the core tube can engage the tube channel, and an inoperative position in which it is pivoted away from the path of the core tube incoming our outgoing with respect to the drill string such that the core tube cannot engage the tube channel, the step of engaging the core tube with the tube prehension device further comprising pivoting the frame towards its operative position.

15. An external core tube displacer for use with a long-reach drilling machine for exploration drilling and core sample collecting of the type comprising a drill string having a first end equipped with a drill bit and a second end opposite the first end, and a core tube movable within the drill string between a first position at the drill string first end and a second position at the drill string second end with a borehole core tube displacer, the external core tube displacer comprising a frame for fixed attachment relative to the drill string, a tube prehension device mounted to the frame and capable of traction on the core tube, and an actuator mounted to the frame and selectively actionable to activate the tube prehension device for allowing the core tube to be displaced relative to the drill string beyond its second position, wherein the tube prehension device and the actuator allow movement of the core tube in two different directions relative to the frame for retrieving the core tube from the drill string and for inserting the core tube into the drill string, and wherein the prehension device includes rollers defining a tube channel therebetween for engagement by the core tube, with the actuator acting on at least some of the rollers to rotate them.

16. The external core tube displacer as defined in claim 15 , wherein the rollers have outer surfaces provided with diamond fragments for providing a high friction coefficient between the outer surfaces and the core tube.

17. The external core tube displacer as defined in claim 16 , wherein the rollers are coated with a friction layer comprising the diamond fragments.

18. The external core tube displacer as defined in claim 15 , wherein at least some rollers are movable with respect to each other between an engaged position in which the at least some rollers are displaced towards the tube channel for grasping the core tube and allowing its retrieval from and insertion into the drill string, and a disengaged position in which the at least some rollers are displaced away from the channel for releasing the core tube.