Patent Publication Number: US-2022235611-A1

Title: Diamond Drilling Hole Correction Tool

Description:
FIELD OF THE INVENTION 
     The present invention relates to industrial drilling. In particular, the invention relates to drill hole correction tools for use in diamond drilling. 
     BACKGROUND OF THE INVENTION 
     During the course of diamond drilling, a drill hole may veer off target. The current methodology for correcting the direction of the drilling by deflecting a drill hole requires use of a metallic wedge within which the outside of the drill bit is carried along the drill hole. The tapered wedge is placed with its wide end at the end of the drill hole. The metallic nature of the wedge makes it harder for the bit to cut than is the rock. As the bit progresses down the hole the bit cuts more material off of the material located in the hole opposite the wedge, thereby causing a corrective deviation from the hole&#39;s previous trajectory. The metal wedge remains in the hole indefinitely. 
     In the first step for placement of a conventional wedge in the hole the drill rods are removed, according to prior art technology. The wedge may then be lowered down the hole and fixed in place. The rods are then lowered back into the hole and the portion of the hole with the wedge is re-drilled, but now in the corrected direction. The process of removing the drill rods from the hole presents the risk that the hole may collapse due to their absence. 
     It is desirable to provide a system in which the rods are never removed from the hole, thereby eliminating the risk of the hole caving in. 
     SUMMARY OF THE INVENTION 
     According to one of its aspects, the present invention provides a diamond drilling hole correction tool for a drill string having a lower latch body, the hole correction tool comprising: an internal push rod attachable to the lower latch body; an external guide cylinder for receiving the internal push rod; a shear pin for fixing the internal push rod to the external guide cylinder; an internal locking pin positioned below the external guide cylinder; and a foot pivotally attached by a pin into a blind slot in the external guide cylinder. The internal push rod may comprise two components, an upper portion and a lower portion, the two portions reversibly detachable. 
     According to another of its aspects, the invention provides a method for correcting the trajectory of a drill hole, the method comprising the steps of: raising the drill rods to a position 3.0 m above the bottom of the drill hole; pulling the inner tube out and removing it from the drill string; deploying an adhesive into the bottom of the drill hole below the drill bit; lowering the hole correction tool of claim  1  down the drill string until the landing ring reaches the landing shoulder and the latches are deployed; rotating the hole correction tool to a desired orientation using an orientation tool; lowering the drill string to press the external guide cylinder into the adhesive until the external guide cylinder reaches the bottom of the hole, thereby shearing the shear pin; further lowering the drill string 6 to 8 inches until a significant load on the drill string is registered by an operator; extending the clamping mechanism and clamping the external guide cylinder in place; allowing the adhesive to cure; retrieving the back end and internal guide rod from the drill hole and removing them from the drill string; and lowering the original standard inner tube down the drill string. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       It is to be expressly understood that the description and drawings are only for the purpose of illustration and as an aid to understanding, which are not intended as a definition of the limits of the invention. In the accompanying drawings, alternate embodiments of the invention are shown by way of example only, in which: 
         FIG. 1  shows a cross-sectional view of the drill hole correction tool assembly of the present invention; 
         FIG. 2  depicts a cross-sectional view of the tool assembly of the invention in place in a drill hole; 
         FIG. 3  depicts a cross-sectional view of the tool assembly of the invention in a drill hole showing the clamping mechanism extended and the external guide cylinder fixed in place; 
         FIG. 4  depicts a cross-sectional view of the tool assembly of the invention with a conventional core barrel replacing the internal pushrod assembly; and 
         FIG. 5  depicts a cross-sectional view of the tool assembly of the invention in a corrected position in the drill hole. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     According to a preferred embodiment of the present invention, the drill hole correction tool consists of 5 components; the internal push rod, the external guide cylinder, the internal locking pin, the foot, and the shear pin. 
     As best seen in  FIG. 1 , the internal push rod is attached to the lower latch body. The internal push rod is inserted into the external guide cylinder and pinned in place with the shear pin. This connection fixes the internal push rod and external guide cylinder relative to one another and prevents them from rotating or sliding within each other. This makes a solid connection from the latch ears down to the foot. The internal locking pin is located below the internal push rod. The foot is inserted into a blind slot in the external guide cylinder at the same end as the internal locking pin. The foot is attached to the external guide rod by a pin, allowing it to pivot. 
     During the diamond drilling process, core is removed from the end of the drill hole through the bit using an inner tube and latch assembly. The latch assembly retains the tube at the bottom of the hole and spins with the rods while the inner tube stays stationary with the core. The latch assembly also contains a landing shoulder which sits on a landing ring inside of the drill rods and prevents the inner tube from being positioned too low inside the string and contacting the drill bit. 
     During the drilling process the hole may deviate from the desired direction. This deviation must be corrected in order for the drill hole to intersect the target. 
     When it has been determined that the hole direction must be changed during normal drilling operations, due to deviation of the trajectory, the rods are first raised 3.0 m from the bottom of the hole. This creates sufficient distance for the external guide cylinder to drop below the bit. The inner tube may then be pulled up and removed from the drill string. 
     Adhesive is then deployed into the bottom of the hole below the bit. 
     The apparatus of the present invention may then be dropped, or lowered, down the drill string. Once the landing ring has reached the landing shoulder and the latches have deployed, the apparatus may be oriented. At this point the external guide cylinder will extend beyond the bit. The clamping mechanism will not be deployed yet and the external guide cylinder and rods will be free to turn within the hole. 
     As may be seen in  FIG. 2 , the external guide cylinder may be oriented to the desired orientation using an orientation tool and twisting the drill string. When the desired orientation is set, the drill string is then lowered, pressing the external guide cylinder into the adhesive below the bit. 
     Once the external guide cylinder reaches the bottom of the hole, the shear pin will shear and the drill operator will see indication of this on this feed gauge. They will then continue to lower the drill string 6 to 8 inches until they see a significant change in the load on the drill string as the internal rods will have travelled all the way down the external guide cylinder and reached the bottom of the hole. The clamping mechanism may now be extended, and the external guide cylinder fixed in place, as shown in  FIG. 3 . 
     When the adhesive has cured, the back end and internal guide rod can be retrieved from the bottom of the hole and removed from the drill string. As shown in  FIGS. 4 and 5 , the original standard inner tube can then be dropped, or lowered, down the drill string. When the tube has landed drilling can commence. 
     Once the inner tube is full as indicated with water pressure, the inner tube can be retrieved from the bottom of the hole and the external guide cylinder and core can be removed as normal. At this point another correction can be drilled, or a standard inner tube can be dropped, or lowered, to the bottom of the hole and drilling can commence as normal. 
     The advantages of the present invention include the ability to drill over something as opposed to beside something to redirect the hole. This allows the hole direction to be corrected without the removal of the drill string from the hole. In addition, the object being drilled over is angled within the hole. The means of fixing or clamping the rod within the hole may be accomplished in a number of ways, either externally as described herein, or internally within the drill string. 
     The material of the object being drilled along may be metallic or non-metallic. In a preferred embodiment, steel is desirable due to its availability and cost. 
     In a preferred embodiment of the present invention, the internal push rod consists of two parts, an upper portion and a lower portion. This permits increased ease of assembly, and allows the push rod to be manufactured in a single piece or multiple pieces. 
     It will be appreciated by those skilled in the art that other variations of the preferred embodiment may also be practiced without departing from the scope of the invention.