AU2017100340A4 - Refurbishing Drill Rods - Google Patents

Abstract

A method of refurbishing a pin tool joint with a single shoulder includes the step of carrying out a manufacturing process on the pin tool joint to form a pin tool joint with a proximal shoulder, a distal shoulder and a tapered thread interposed between the proximal and distal shoulders, and a projection that extends coaxially from and with respect to a distal end of the tapered thread. 22 219.1 16 - ..20 17 - 18- 1 10 Figure 2

Description

1 2017100340 23 Mar 2017

REFURBISHING DRILL RODS

Field

Various embodiments of a method of refurbishing drill rods are described herein. Summary

According to one aspect, there is provided a method of refurbishing a pin tool joint with a single shoulder that includes the step of carrying out a manufacturing process on the pin tool joint to form a pin tool joint with a proximal shoulder, a distal shoulder and a tapered thread interposed between the proximal and distal shoulders, and a projection that extends coaxially from and with respect to a distal end of the tapered thread.

The manufacturing process may be a reductive process. For example, the manufacturing process may be a machining process.

Instead, the manufacturing process may be an additive process. The method may include the step of arranging the projection on a distal end of the tapered thread. The method may include forming a bore in a distal face of the tapered thread and fitting a tubular member in the bore to define the projection.

The manufacturing process may be carried out so that a refurbished pin tool joint is of substantially the same length as the pin tool joint prior to refurbishment.

The method may include the step of performing a manufacturing process on the box tool joint to form a recess to accommodate the projection formed in the method.

In another aspect, a drill string component includes: a drill pipe; a box tool joint at a proximal end of the drill pipe; a pin tool joint at an opposite, distal end of the drill pipe and with a tapered thread interposed between a proximal shoulder and a distal shoulder; and a projection that extends coaxially from and with respect to a distal end of the tapered thread, wherein the pin tool joint and the projection are the result of a manufacturing process carried out on a pin tool joint with a single shoulder. 2 2017100340 23 Mar 2017

The projection may be cylindrical and may define a bore that is aligned with a bore of the drill pipe.

The box tool joint may define an internal recess that accommodates the projection, the internal recess being the result of a manufacturing process carried out on a conventional box tool joint.

The projection may be defined by a tubular member that is arranged on the distal end of the rotary shouldered connection. The tubular member may be seated in a bore formed in the tapered thread and coaxial with a conduit of the drill string component.

In another aspect, there is provided a method for refurbishment of a drill string component having a drill pipe with a box tool joint at a proximal end and a pin tool joint at an opposite, distal end, the pin tool joint having a rotary shouldered connection that terminates the pin tool joint, the method including the steps of: machining the pin tool joint so that a refurbished rotary shouldered connection is formed and the pin tool joint is terminated by a projection that extends coaxially from the rotary shouldered connection; removing an end portion of the box tool joint; and machining the inner box tool joint portion internally to accommodate the projection when the pin tool joint of one component is screwed into the box tool joint of an adjacent component.

The pin tool joint may be machined so that an end face of the rotary shouldered connection prior to machining defines the end face of the projection after machining.

The following paragraphs are intended to assist in understanding the environment in which the methods and components described above are intended to be used.

When drilling overburden in surface mines, drill rigs are used to drill overburden above the ore or coal to enable blasting of the overburden for conveyance of the material by drag lines or truck and shovel fleets. The hole diameters used for blasting overburden typically range from 203 mm up to 270 mm and are drilled to a maximum depth of around 80 m to 90 m with an average hole depth of around 50 m. The hole is formed by the drill rod being rotated and pushed into 3 2017100340 23 Mar 2017 the earth while compressed air flows through a centre conduit of the drill rod to clear the cuttings up past the outside of the drill rod. A drill bit is fitted to the bottom of a lead drill rod that cuts and gouges the earth with the drill bit generally being 25mm-75mm larger than the drill rod. There can be up to six drill rods carried on the drill rig in a carousel which enables the rig to drill the first rod down and then connect the second drill rod onto the lead drill rod and drill it down as well. This process is continued until the correct hole depth is achieved. The process is reversed until all the drill rods are racked away into a carousel and the drill can tram to the next hole position in the drill pattern and drill the next hole. The drill rods in the carousel generally drill between 70,000 m and 200,000 m before the threads that connect them are worn out and require replacing. The drill rods are then removed from the rig and are replaced so that drilling operations can continue.

The rods that are removed may be able to be refurbished. This is a process in which the drill rod is re-manufactured to ensure that critical dimensions on the drill rod are renewed and the drill rod can be fitted to the drill rig for another period of drilling.

Carousels are fitted to rotary drill rig masts to enable storage and handling of several drill rods. The carousel moves in and out of a centre line of the rotary head in the mast/tower to enable the drill rod to be picked up by coupling with the rotary head. The carousel then is moved out of the way of the rotary head as it rotates and pushes the drill rod into the ground.

Since the mid 1990's diesel/hydraulic drill rigs have become the industry norm. These drill rigs generally require a shoulder to shoulder length of the drill rod to remain constant within plus or minus 6 mm. Drill rods are normally between about 10 metres and 17 metres long. Normally, the reason the drill rods are removed from a drill rig is thread wear. To repair or refurbish the drill rod, the worn thread is either re-cut in a hollow spindle lathe or a section of the tool joint is sawn off and a new section is welded in to replace it. The process of saw cutting, machining a weld preparation on the remaining section of the tool joint and machining a replacement section of tool joint and then welding this replacement section/s onto the drill rod involves labour and materials. 2017100340 23 Mar 2017 4

The drill rods can have the thread in the box tool joint recut in a CNC hollow spindle lathe. However, it is usual for at least 25mm of length to be lost from the box end. That must be made up on the pin tool joint end to maintain the correct shoulder to shoulder length. The replacement section of pin tool joint is manufactured longer to compensate for the loss on the box end. There are various reasons for maintaining a close tolerance on the shoulder to shoulder length of a drill rod and the correct position of the recesses and flats or "wrenching" machined into the tool joints in relation to the shoulder faces on each end of the drill rod. Without maintaining the tolerance: 1. The drill rod may fall out of the carousel when the mast is in its drilling position, that is, generally vertical. 2. The drill rod may fall out of the carousel when the mast is in its tramming position, that is, generally horizontal

Regarding the first reason, the wrenching must be maintained in a position to enable normal drilling operations. It is possible to alter the position of the top retaining plate of the carousel of the drill rig and alter the wrenching position on the drill rod and still drill normally. However, this can be costly and timeconsuming.

Regarding the second reason, there is a device fitted to most carousels called an axial retaining plate that stops the drill rod sliding towards the rotary head while tramming up a slope. The axial retaining place is designed so that the pin thread of the drill rod can slide until contacting the axial retaining place without being able to drop out of the top retaining plate in the carousel.

In the method and apparatus described above, rather than replace the pin section of the tool joint when the thread is worn out, as is done conventionally, the pin thread on the tool joint may be re-machined but not faced off in a machining process, to leave excess pin thread material to define a projection or spigot. This projection or spigot stops the pin tool joint wrenching dropping out of the top retaining plate on the carousel. There are potentially a couple of problems arising from recutting the pin thread and leaving a spigot at the top of this thread. 2017100340 23 Mar 2017 5 1. The spigot may contact the material at a back of the box thread, causing damage to the spigot and stopping the threads of the box and pin coupling up. 2. If the box tool joint is recut as well and is shortened, the pin wrenching may be in the incorrect location and the drill rod may drop out of the top retaining plate of the carousel during drilling operations.

Regarding point 1, the method may include machining the clearance for the pin thread spigot into the profile of the box thread.

Regarding point 2, the method may include fitting a spacer into a bottom pot of the carousel which would then pack the box thread face back into its original position thereby ensuring the pin wrenching is in its original position. This can be done by placing a spacer in the pot. The spacer may be a disc of predetermined thickness.

Brief description of the Drawings

Figure 1 shows an end of a drill rod with a pin tool joint being the result of a refurbishment process carried out on a conventional pin tool joint.

Figure 2 depicts a prior art conventional drill rod prior to the refurbishment process.

Figure 3 shows a prior art pin tool joint on the conventional drill rod prior to refurbishment.

Figure 4 shows the pin tool joint of figure 3 and a prior art box tool joint of the conventional drill rod.

Figure 5 shows the pin tool joint of figure 3 with typical dimensions.

Figure 6 shows the box tool joint of figure 4 with typical dimensions.

Figure 7 shows the conventional pin tool joint and box in an assembled condition.

Figure 8 shows a box tool joint that is the result of a refurbishment process and a conventional pin tool joint coupled to the box tool joint.

Figure 9 shows the box tool joint of figure 8. 6 2017100340 23 Mar 2017

Figure 10 shows the pin tool joint of figure 1 coupled to the box tool joint of figure 8.

Figure 11 shows the pin tool joint of figure 1 with illustrative dimensions.

Figure 12 shows the box tool joint of figure 9 with illustrative dimensions.

Figure 13 shows the conventional pin tool joint prior to a refurbishment process.

Figure 14 shows a pin tool joint after a first refurbishment process is carried out on the conventional pin tool joint.

Figure 15 shows the pin tool joint of figure 14 after a second refurbishment process carried out on the pin tool joint of figure 14.

Figure 16 shows a side view of a further example of a pin tool joint after a refurbishment process carried out on a conventional pin tool joint.

Figure 17 shows a three-dimensional view of the pin tool joint of figure 16.

Figure 18 shows a further view of the pin tool joint of figure 17.

Figure 19 shows a three-dimensional view of a prior art drill rig carousel.

Figure 20 shows a side view of a bottom portion of the carousel of figure 19.

Figure 21 shows a side view of a top portion of the carousel of figure 19.

Figure 22 shows a section C-C of the carousel of figure 20.

Figure 23 shows a section D-D of the portion of the carousel of figure 20.

Figure 24 shows a section A-A of the portion of the carousel of figure 21.

Description of Embodiments

In figure 1, reference numeral 100 generally indicates a pin tool joint that is the product of a refurbishment process carried out on a conventional pin tool joint that will be described in further detail below.

The pin tool joint 100 includes a body 101 that is mounted or fastened to a drill pipe 10 (figure 2). The body 101 is fastened to the drill pipe 10 in a conventional manner, such as by welding.

The pin tool joint 100 includes a tapered thread 104 that is interposed between a proximal shoulder 106 and a distal shoulder 108. 7 2017100340 23 Mar 2017 A projection or spigot 102 extends coaxially from, and with respect to, a distal end of the tapered thread 104. A conventional drill rod is shown in figure 2. The drill rod includes a drill pipe 10. An annular proximal recess 12 and an annular distal recess 14 are defined near proximal and distal ends, respectively, of the drill pipe 10. The drill pipe 10 defines an internal conduit 11 (shown in further figures). A conventional pin tool joint 16, for example a rotary shoulder tool joint, has a body 17 that defines a socket 18 that receives a complementary distal end portion 20 of the pipe 10 to secure the pin 16 to the pipe 10. The pin 16 includes a taper thread 22 and a shoulder 24 interposed between the taper thread 22 and the shoulder 24. A conventional box tool joint 25 is secured to a proximal end of the pipe 10.

Figure 3 shows the conventional pin tool joint 16 in further detail. The pin tool joint 16 is configured to terminate about 50 mm from the underside of a conventional axial retaining place (not shown) mounted on a conventional carousel, an example of which is described below with reference to figures 19 to 24.

Figure 4 shows the pin tool joint 16 and the box tool joint 25 prior to coupling by threading the taper thread 22 into engagement with an internal complementary taper thread 26 of the box tool joint 25. As can be seen in figure 4, the box tool joint 25 has a body 28 that defines an internal volume 30. The taper thread 22 is received in the volume 30 when engaged with the taper thread 26.

Figure 5 shows the pin tool joint 16 with illustrative dimensions. These are provided by way of example, only.

Figure 6 shows the box tool joint 25 also with illustrative dimensions. Again, these are provided by way of example, only.

Figure 7 shows the pin tool joint 16 coupled with the box tool joint 25 by the taper thread 22 threaded into the taper thread 26. The internal volume 30 is configured so that, when the pin tool joint 16 is engaged with the box tool joint 25 and the shoulder 24 bears against a face 34 of the box tool joint 25, a space 32 is defined at a distal end of the pin tool joint 16 to prevent damage to the taper thread 22. 8 2017100340 23 Mar 2017

Figure 8 shows the pin 16 coupled with a box tool joint 110 that is the result of a manufacturing process carried out during refurbishment of the box tool joint 25. The box tool joint 110 includes a recess 112 that is formed by boring into the body 28 such that the recess 112 can accommodate the spigot 102 (figure 10). When the box tool joint 110 is formed, or manufactured, the face 34 is machined away so that the body 28 is faced off to an extent that is equivalent to a length of the spigot 102. This extent can vary with a typical example being 25 mm.

Figure 9 shows the box tool joint 110 by itself. As can be seen more clearly in this drawing, the internal volume 30 and the recess 112 are formed to define an internal shoulder 114.

Figure 10 shows the pin tool joint 100 coupled to the box tool joint 110 with the tapered thread 26 engaged with the tapered thread 104. As can be seen, the spigot 102 is received in the recess 112 and the face 34 abuts the proximal shoulder 106. Also, the distal shoulder 108 is spaced from the internal shoulder 114 to provide clearance and to avoid damage to the tapered thread 104.

Figure 11 shows the pin tool joint 100 with illustrative dimensions. These are provided by way of example only.

Figure 12 shows the box tool joint 110 with illustrative dimensions. These are provided by way of example only.

Figure 13 shows the conventional pin tool joint 16. Figure 14 shows the pin tool joint 100 fabricated or formed from a refurbishment manufacturing process carried out on the pin tool joint 16. Figure 15 shows the pin tool joint 100 after a further refurbishment manufacturing process. In each of the processes resulting in the pin 100 shown in figures 14 and 15, no removal of material from a distal end of the pin 16 occurs. This results in the generation of the spigot 102. Thus, the refurbishment process results in the transformation of the conventional pin tool joint 16 into a non-conventional pin tool joint. This is in contrast with conventional refurbishment processes wherein a conventional pin tool joint replaces the conventional pin tool joint 16.

In figures 16 to 18, reference numeral 120 generally indicates a further example of a pin tool joint formed during a refurbishment process carried out on the conventional pin tool joint 16. 9 2017100340 23 Mar 2017

In this example, once the pin tool joint 16 is refurbished in the conventional manner, a bore 122 is formed in the tapered thread 22. Thus, the internal conduit 11 opens into the bore 122 such that a shoulder 124 is interposed between the conduit 11 and the bore 122. A tubular member, for example a length of pipe 126 is fitted into the bore 122 to extend from the bore 122. The length of pipe 126 is dimensioned, and the shoulder 124 is positioned, so that the pipe 126 extends from the tapered thread 22 to an extent that is equivalent to a length of material lost during refurbishment of the pin 16. Thus, the length of pipe 126 extending from the tapered thread 22 is equivalent to the projection or spigot 102.

In figure 19, reference numeral 130 generally indicates a conventional pipe carousel for a drilling rig. Figure 20 shows an operatively lower portion of the carousel 130. Figure 21 shows an operatively upper portion of the carousel 130.

The carousel 130 includes a central shaft 134 with a pot 132 mounted at an operatively lower end of the central shaft 134. A bottom rack plate 136 is mounted on the central shaft 134 near the bottom pot 132. A top rack plate 138 is mounted on the central shaft 134 near a top of the shaft 134. A pair of intermediate rack plates 140 are mounted on the shaft 134 between the top and bottom rack plates 136, 138.

Figure 22 shows a plan view of one of the intermediate plates 140. Figure 23 shows a plan view of the top plate 138. Figure 24 shows a plan view of the bottom plate 136.

Each of the plates defines radial slots 142. Carousels can have different numbers of radial slots. In this case, the plates of the carousel have five slots.

As is known, drill rods are racked on the carousel 130 with portions of the drill rods received in respective slots 142. Figure 2 shows an example of such a drill rod. Thus, the slots 142 in the respective plates 136, 138, 140 are dimensioned to accommodate the portions of the drill rods. In this case, the body 17 of the pin tool joint 16 is received in one of the slots 142 of the plate 138 while the body 28 of the box tool joint 25 is received in one of the slots 142 of the plate 136.

It will be appreciated that shortening the pin tool joint 16 in a refurbishment operation can result in the body 17 of the pin tool joint 16 not being properly 2017100340 23 Mar 2017 10 received in a corresponding slot 142. This can cause the drill rod to fall out of the carousel 130.

In many drilling arrangements, the top rack plate 138 is close to a face of the taper thread 22. For example, with many carousels, the top plate is generally 50 mm to 75 mm thick. Thus, if, as a result of refurbishment, the face of the taper thread 22 is moved, say 25 mm, which is conventional, towards a proximal end of the drill pipe 10, and 25 mm, which is also conventional, is machined off the face 34 of the box tool joint 25, the face of the taper thread 22 can be lined up or even below a bottom face of the carousel plate 138 causing the carousel plate not to carry out its function to retain the drill rod in the carousel plate 138.

In the past, it has been possible to address this problem by adjusting a position of the carousel plate 138 as shown in figure 21. However, more recently, carousel manufacturers have provided carousels with plates that are not adjustable.

The spigot 102 of the pin tool joint 100 maintains a length of the conventional tool joint 16 prior to refurbishment of that pin tool joint 16. Thus, the problem associated with the face of the taper thread 22 being lined up with a bottom face of the carousel plate can be ameliorated. Furthermore, facing off the body 28 of the conventional box tool joint 25 can be accommodated by placing a spacer in the bottom pot 132.

In one example, to modify or convert the conventional pin tool joint 16 into the pin tool joint 100, the drill rod is set up in a hollow spindle CNC lathe. The pin profile of the pin tool joint 100 is machined over the existing taper thread 22 and shoulder 24.

In one example, to modify the conventional box tool joint 25, the drill rod is set up in a hollow spindle CNC lathe. A certain length, for example 25 mm, is machined off the face 34. A fresh profile is machined into the internal volume 30 to generate the recess 112. The thread 26 is recut or machined into the correct gauge fit.

The appended claims are to be considered as incorporated into the above description. 2017100340 23 Mar 2017 11

In the specification, the word "distal" is intended to mean a position that is towards or at the pin tool joint even if the pin tool joint is not on the drill pipe. "Proximal" is intended to mean a position that is towards or at the box tool joint even if the box tool joint is not on the drill pipe.

Also in the specification, words indicating orientation or position, such as, "up", "down", "forward", "back", et cetera are used for convenience only and should not be limiting. The inventor(s) envisages that the drill string component can be supplied in any number of different orientations.

Throughout the specification, including the claims, where the context permits, the term "comprising" and variants thereof such as "comprise" or "comprises" are to be interpreted as including the stated integer or integers without necessarily excluding any other integers.

It is to be understood that the terminology employed above is for the purpose of description and should not be regarded as limiting. The described embodiments are intended to be illustrative of the invention, without limiting the scope thereof. The invention is capable of being practised with various modifications and additions as will readily occur to those skilled in the art.

Claims (15)

1. A method of refurbishing a pin tool joint with a single shoulder includes the step of carrying out a manufacturing process on the pin tool joint to form a pin tool joint with a proximal shoulder, a distal shoulder and a tapered thread interposed between the proximal and distal shoulders and a distal shoulder, and a projection that extends coaxially from and with respect to a distal end of the tapered thread.

2. The method as claimed in claim 1, in which the manufacturing process is a reductive process.

3. The method as claimed in claim 2, in which the manufacturing process is a machining process.

4. The method as claimed in claim 1, in which the manufacturing process is an additive process.

5. The method as claimed in claim 4, which includes the step of arranging the projection on a distal end of the tapered thread.

6. The method as claimed in claim 5, which includes the step of forming a bore in a distal face of the tapered thread and fitting a tubular member in the bore to define the projection.

7. The method as claimed in claim 1, in which the manufacturing process is carried out so that a refurbished pin tool joint is of substantially the same length as the pin tool joint prior to refurbishment.

8. A method of refurbishing a box tool joint includes the step of performing a manufacturing process on the box tool joint to form a recess to accommodate the projection formed in the method of claim 1.

9. A drill string component that includes: a drill pipe; a box tool joint at a proximal end of the drill pipe; a pin tool joint at an opposite, distal end of the drill pipe and with a tapered thread interposed between a proximal shoulder and a distal shoulder; and a projection that extends coaxially from and with respect to a distal end of the tapered thread, the pin tool joint and the projection being the result of a manufacturing process carried out on a pin tool joint with a single shoulder.

10. The drill string component as claimed in claim 9, in which the projection is cylindrical and defines a bore that is aligned with a bore of the drill pipe.

11. The drill string component of claim 9, wherein the box tool joint defines an internal recess that accommodates the projection, the internal recess being the result of a manufacturing process carried out on a conventional box tool joint.

12. The drill string component as claimed in claim 9, in which the projection is defined by a tubular member that is arranged on the distal end of the tapered thread.

13. The drill string component as claimed in claim 12, in which the tubular member is seated in a bore formed in the tapered thread and coaxial with a conduit of the drill string component.

14. A method for refurbishment of a drill string component having a drill pipe with a box tool joint at one end and a pin tool joint at an opposite end, the pin tool joint having a rotary shouldered connection that terminates the pin tool joint, the method including the steps of: machining the pin tool joint so that a refurbished rotary shouldered connection is formed and the pin tool joint is terminated by a projection that extends coaxially from the rotary shouldered connection; removing an end portion of the box tool joint; and machining the box tool joint internally to accommodate the projection when the pin tool joint of one component is screwed into the box tool joint of an adjacent component.

15. The method as claimed in claim 14, in which the pin tool joint is machined so that an end face of the rotary shouldered connection prior to machining defines the end face of the projection after machining.