Field of the Invention

[0001] The present invention relates to an apparatus and methods used during percussion drilling operations.

Background

[0002] The following discussion of the background art is intended to facilitate an understanding of the present invention only. It should be appreciated that the discussion is not an acknowledgement or admission that any of the material referred to was part of the common general knowledge as at the priority date of the application.

[0003] Percussion drilling, such as reverse circulation drilling, uses a bit which is repeatedly hammered to fracture rock and progressively drill or bore through the earth. Percussion drilling creates a harsh environment which is not conducive to measuring tools and components which are sensitive to rapid changes in motion and/or repeated impacts with the associated shock/vibration.

[0004] T raditional methods of percussion drilling operations are conducted in at least two stages which include a drilling stage and a logging stage. During the drilling stage a drill string is mechanically operated by drilling machinery. Following which, the second stage requires separately lowering additional equipment to log information about the hole that has been drilled including depth, density and gamma radiation of the drilling formation.

[0005] Devices that can reduce and/or eliminate the need or timing of the second stage are commonly sought. It is against this background that the present invention is presented.

[0006] Throughout the specification unless the context requires otherwise, the word “comprise” or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

[0007] Throughout the specification unless the context requires otherwise, the word “include” or variations such as “includes” or “including”, will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers. Summary of Invention

[0008] According to a first aspect there is provided a drill rod comprising a body comprising one or more fluid supply channels, a fluid return channel and one or more compartments.

[0009] In an embodiment, a cross-sectional area of the one or more compartments is greater that a cross-sectional area of the one or more fluid supply channels.

[0010] In an embodiment, a cross-sectional profile of the one or more compartments is different to a cross-sectional profile of the one or more fluid supply channels.

[0011] In an embodiment, at least one of the one or more compartments comprises an opening in the radial direction of the body for access to the compartment.

[0012] In an embodiment, the one or more compartments are within the outer diameter of the body.

[0013] In an embodiment, the body is adapted for coupling with a fluid supply of another drill rod having multiple annuluses.

[0014] In an embodiment, the body comprises a casing.

[0015] In an embodiment, the casing encloses the one or more compartments.

[0016] In an embodiment, the casing is adapted for coupling with another drill rod having multiple annuluses.

[0017] In an embodiment, the body comprises a manifold connecting the plurality of supply channels.

[0018] In an embodiment, the manifold converts a supply channel formed by a void between the annuli of the other drill rod to the one or more supply channels.

[0019] In an embodiment, the manifold is adapted for coupling with another drill rod having multiple annuluses.

[0020] In an embodiment, the one or more compartments extend longitudinally along a portion of the body. [0021] In an embodiment, the one or more compartments is separated into one or more subcompartments.

[0022] In an embodiment, the sub-compartments are arranged to be longitudinal with respect to a length of the drill rod.

[0023] In an embodiment, the body comprises one or more additional smaller compartments.

[0024] In an embodiment, there are a plurality of supply channels and a respective compartment between two of the supply channels.

[0025] In an embodiment, the one or more smaller compartments form a channel extending circumferentially from a lower end of a first compartment to an upper end of a second compartment located on an opposite side of the body to the first compartment.

[0026] In an embodiment, the channel is recessed into the body and provides a conduit for securing cabling to communicate between multiple measuring instruments between compartments located at different radial positions on the body.

[0027] In an embodiment, there are a plurality of compartments and a respective supply channel between two of the compartments.

[0028] In an embodiment, the supply channels are configured to supply pressurised air.

[0029] In an embodiment, the return channel is configured to receive air laden with cuttings.

[0030] In an embodiment, the one or more compartments comprise mounts for one or more measuring tools and/or a power source.

[0031] In an embodiment, the one or more compartments is formed by a recess into the body.

[0032] In an embodiment, one or more of the compartments is dimensioned to receive a measuring instrument. In an embodiment the compartment is larger than the received measuring instrument so that there is a gap provided between the measuring instrument and walls of the compartment.

[0033] In an embodiment, one or more of the compartments is shaped to be generally U shaped in cross-section. In an embodiment, the compartment comprises a substantially flat base. [0034] In an embodiment, the compartment comprises sloped sidewalls that are wider apart at an opening of the compartment than the sidewalls are apart at the base.

[0035] In an embodiment, the fluid return channel comprises a cross-sectional area substantially the same as a combined cross-sectional area of the fluid supply channels.

[0036] According to a second aspect there is provided a drill apparatus comprising a body comprising one or more fluid supply channels, a fluid return channel and one or more compartments.

[0037] According to a third aspect there is provided a method of percussion drilling comprising transferring fluid from a first end of a drill rod to a second end of the drill rod via a plurality of fluid supply channels and transferring returning fluid from the second end to the first end via a return channel.

[0038] In an embodiment, the fluid flow to supply channels is separated into the supply channels via a first manifold at the first end. In an embodiment, the fluid flow from supply channels is joined via a second manifold at the second end.

Brief Description of Drawings

[0039] Preferred embodiments of the invention will now be described with reference to the following drawings, in which:

Figure 1 is a side view of a drill rod comprising a damping apparatus according to an embodiment of the present invention;

Figure 2 is a side view of the drill rod without the casing showing the damping apparatus according to an embodiment of the present invention;

Figure 2A is an isometric view of the casing which may cover the damping apparatus according to an embodiment of the present invention;

Figure 2B is an isometric view of the measuring instruments coupled to the damping apparatus within the body according to an embodiment of the present invention;

Figure 3 is a cross-sectional view of the drill rod having the damping apparatus mounted within according to an embodiment of the present invention; Figure 4 is an isometric view of a plate which measuring instruments may be coupled to according to an embodiment of the present invention;

Figure 5 is a cross-sectional view of the drill rod having inner compartments with a damper apparatus according to an embodiment of the present invention;

Figure 6 is an isometric view of a body of the drill rod having compartments arranged longitudinally around the perimeter of the body according to an embodiment of the present invention;

Figure 7 is a cross-sectional view of supply channels and a return channel according to an embodiment of the present invention;

Figure 7 A is an isometric view of a manifold according to an embodiment of the present invention; and

Figure 8 is a cross sectional view of the body according to an embodiment of the invention.

Description of Embodiments

[0040] Referring to Figures 1 , 2, 2A, 2B and 3 there is provided drill rod 5 comprising an elongate body 10 within a cylindrical casing 12 having ends suitable for connection into a percussion drilling drill string in place of a standard drill rod. Typically, this will be immediately behind the bottom hole assembly including the drill head in the drill string since the measurements are desired to be taken from a position immediately behind the drill head.

[0041] The body 10 comprises longitudinally extending compartments 212 arranged around an outer diameter of the body 10. Each compartment 212 is in the form of a recess or slot as seen in Figures 2B and 8. In an embodiment there are two large compartments 212 on opposite sides of the body 10. The large compartments 212 are able to receive one or more measuring instruments 180, as described further below. In an embodiment there may be additional compartments, such as smaller compartments 212’ on opposite side of the body 10, and each between two of the larger compartments 212. Each of the compartments 212 may have one or more attachment means for securing a mount 122 to the body 10, typically at a side wall of the compartment 212. In an embodiment the attachment means is in the form of one or more screws or bolts 112 in threaded engagement with a corresponding hole in the side wall 114 (see Figure 12A). This facilitates placement, installation and removal of the measuring instruments 180. Furthermore, the holes in the side wall 114 of the body allow for adjustment of positioning of each damping apparatus 110 thereby allowing for longer or shorter measuring instruments to be placed in each of the compartments 212 at a desired position therein. [0042] Percussion drilling is an umbrella term that includes but is not limited to, reverse circulation drilling and air core drilling. The present invention may be suitable for any form of drilling where the drill string experiences high impact and/or repetitive impact forces. The forces that the measuring instrument 180 experiences may be axial, radial and/or rotational shock/vibration experienced independently, or a combination of the aforementioned. Such forces may impede the measuring instrument 180 from collecting accurate data and/or functioning entirely.

[0043] Throughout the specification the backplate 184 and measuring instrument 180 should be interpreted as being interchangeable with any measuring tool or apparatus having supports 186 affixed at respective longitudinal ends with dimensions which fit within the compartments 212, such as gamma detector 182. To fit within the compartments 212 the length of the measuring tool 180 and damping apparatuses 110 must line up with a respective hole in the sidewall 114 of the compartment 212.

[0044] Figure 4 shows the backplate 184 suitable for fixing the measuring instrument 180 or other componentry such as a PCB board. The backplate 184 has a length such that each longitudinal end comprises a support 186. The damping apparatuses 110 are affixed to the body 10 such that the backplate 184 and measuring instrument 180 are fixed in a damped arrangement between the damping apparatuses 110.

[0045] The spatial positioning of the measuring instruments 180 within the compartments 212 can be seen in Figure 5. In this embodiment, the measuring instruments 180 are affixed between two damping apparatuses 110. The damping apparatuses 110 are spaced apart longitudinally to provide support along the length of the backplate 184. Alternative embodiments may require more or less damping apparatuses 110 which will be discussed in detail below. During a percussion drilling operation, the black plate 184 measuring instrument 180 can move such as for example illustrated by the double headed arrows. Sufficient clearance is provided between the extreme dimensions of the black plate 184 measuring instrument 180 and the inside surface of the compartment 212 and the inside wall of the casing 12 such that contact does not occur.

[0046] Figure 5 shows the body 10 in more detail it has a plurality and in this case four supply channels 318 which receives air from a single annulus of a standard double walled drill rod to the upper end 14 of the body 10. The backplate 184 has the measuring instrument 180 within the compartments 212 isolated from the fluid supply channels 318 and a fluid return channel 320. The fluid return channel 320 receives fluid from the bottom hole assembly at the lower end 18 of the body 10 and provides it to a central tube of the standard double walled drill rod.

[0047] The cross-sectional area of the compartment 212 may be greater than the cross- sectional area of the fluid supply channels 318, thus allowing for a measuring instrument 180 of greater dimensions to be housed within the compartment 212 than would be able to be housed in a compartment having the same cross-sectional area as the fluid supply channels 318.

[0048] The cross-sectional profile of the compartment 212 may be different than the cross- sectional profile of the fluid supply channels 318, which are beneficially round, thus allowing for a measuring instrument 180 of different proportions to be housed within the compartment 212 than would be able to be housed in a compartment having the same cross-sectional profile as the fluid supply channels 318.

[0049] The different cross-sectional area and/or profile of the compartment is advantageous as the incorporation of a wider variety of measuring instruments 180 is enabled.

[0050] The compartments 212 may be shaped to be generally U shaped in cross-section.

[0051] The compartment may comprise a substantially flat base.

[0052] The compartment 212 may comprise sloped sidewalls that are wider apart at an opening of the compartment 212 than the sidewalls are apart at the base.

[0053] The compartment 212 may comprise an opening in the radial direction of the body 10 for access to the compartment 212.

[0054] The radial opening facilitates access to the compartment 212 when the casing 12 is removed.

[0055] Referring to Figures 6, 7 and 7A, the upper end 14 of the body 10 comprises a chamber which acts as a manifold 324 to direct fluid from a surface unit uphole into the fluid supply channels 318. The present embodiment provides four fluid supply channels 318 as this allows for the two larger compartments 212 and the two smaller compartments 212’ described above. Alternative embodiments may have one, two, three, five or more fluid supply channels based on the specific application. At the lower end 18 of the body 10 there is the reverse of manifold 324 which allows for the four fluid supply channels 318 to combine in a chamber and continue to the next drill rod, likely, the bottom hole assembly, but possibly another drill rod. [0056] The fluid return channel 320 eventually receives return of the fluid provided through the fluid supply channels 318 as well as any cuttings or debris produced from the drilling operations. Due to the fluid return channel 320 comprising solid debris it is typically of a larger diameter relative to the fluid supply channels 318. The fluid return channel 320 is fluidly isolated from the fluid supply channels 318 and compartments 212, 212’. The fluid return channel 320 is defined by the fluid return pipe 322 which connects to each successive drill rod from the bottom hole assembly up to a surface return unit, such as a cyclonic separator, container or sample bag.

[0057] The fluid supply channels 318 supply working fluid from a surface unit (not shown) through the body 10 providing compartments 212, 212’ without impeding the volumetric flow rate of fluid required to operate the bottom hole assembly, such as to provide pressurised air to the hammer and drill bit in reverse circulation drilling.

[0058] In an embodiment, the fluid return channel 320 comprises a cross-sectional area substantially the same as a combined cross-sectional area of the fluid supply channels 318.

[0059] Referring to Figure 8, there is provided a cross section of the body 10 showing the fluid supply channels 318 and the fluid return channel 320. As discussed above, the compartments 212 are larger than the compartments 212’. The compartments 212’ may provide a channel for cables. The channel may extend from the lower end of compartment 212 to the upper end of the other compartment 212 located on the opposite side. A circumferentially extending channel recessed into the body 10 above and below the compartments 212 provides a conduit for securing cabling to communicate between multiple measuring instruments 180, 182 between compartments 212 located on opposite sides of the body 10.

[0060] In use, measuring the orientation of a measurement tool during percussion drilling operations comprises drilling a hole using a drill string having a percussion drill bit and a measuring instrument; and measuring the orientation of the tool as the hole is being drilled. As the drill string progressed into the drilled bore hole the action of the percussion drill bit is paused to add another drill rod, and when the drill string is extracted drill rods are removed. During each pause in drilling the measuring instrument takes a calibration measurement. The fluid, such as pressurised air can flow through the supply channels 318 to the hammer and returning fluid, such as air laded with cuttings can flow through the return channel 320, whilst still allowing the compartments 212 for holding the measuring instruments 180, which are not spatially able to be accommodated in a standard drill rod. [0061] As discussed above, with reference to the manifold 324, the upper portion of the body 10 comprises connection means for fluidly connecting to a multi annulus drill rod at the upper end of the body 10 as well as below at the lower end of the body 10. The fluid return channel 320 connects directly to the fluid return channels of the drill rod immediately above and below the body 10 to fluidly isolate the fluid return channel 320. The annulus of the drill rod above the body 10 in the drill string fluidly connects with the manifold 324 of the upper end of the body 10. The manifold 324 directs the supply fluid through the fluid supply channels 318 to the lower end of the body 10 to a chamber which fluidly connects with the annulus of the drill rod or bottom hole assembly below the body.

[0062] In the context described herein, pneumatic percussion drilling is where there is a hammer actuated by pressurised air that strikes an anvil component of or connected to a drill bit so that the drill bit impacts on rock on the bottom of a drill hole so as to break the rock. The hammer is directly next to the drill bit. This type of percussion drilling is used in rotary air blasting (RAB) and reverse circulation drilling (RC drilling). Pneumatic percussion drilling is used in mineral exploration. It is to be distinguished from hydraulic (often water or mud) powered percussion drilling used in hydrocarbon well drilling. It is also to be distinguished from mechanical percussion drilling where the drill string is lifted and dropped, usually from the surface. In hydraulic and mechanical percussion drilling a casing within which the drill string can move is usually used. However, in pneumatic percussion drilling a casing is usually not used.

[0063] RC drilling will be understood to be where the pressurised air flow is also used to blow the rock broken by the drill bit impact into one or more holes in the drill bit and then up through the drill string. The drill rods have an inner tube through which the air and recovered rock return to the surface and an outertube, which between this and the innertube, the pressurised airtravels down the drill string to the hammer and the drill bit. This is distinguished from RAB, which is where the broken rock air is blown up the drill hole outside of the drill string. The innertube is not required in the drill rods for RAB.

[0064] Percussion drilling can be distinguished from air core drilling where the drill bit cuts, rather than breaks from impact, but there is pressurised air that returns the cuttings through the drill string. Percussion drilling can also be distinguished from diamond core drilling where ring is cut by diamond teeth and a core sample can be retrieved.

[0065] Modifications may be made to the present invention within the context of that described and shown in the drawings. Such modifications are intended to form part of the invention described in this specification.