FLOW RESTRICTOR AND DRILLING ASSEMBLY

Abstract

A flow restrictor comprising a body adapted to restrict a flow of fluid through a drill rod passage, the body having a coupling for coupling said body into the drill rod passage, said body defining an upstream fluid receiving passage, a downstream fluid egress passage, and a passage of restrictive diameter between said passages to limit the flow of fluid in the drill rod passage.

Description

FIELD

The present disclosure relates generally to drilling operations, drill rods and components thereof and drilling assemblies.

BACKGROUND

It is necessary during all drilling operations to deliver a fluid, such as water, to the cutting face to remove debris as it forms around the drill bit and, in some instances, to cool the drill tips. The fluid can be delivered to the drill bit by passing the fluid through a central passage of the drill rod.

In mining operations, such as underground coal mines, substantial volumes of water are used in drilling operations and consequently similar volumes of waste water are generated. The waste water may accumulate and provide a safety hazard in the vicinity of mining operations, such as underground mine roadways, and therefore requires disposal or mitigating measures to be implemented.

The above references to the background art do not constitute an admission that the art forms a part of the common general knowledge of a person of ordinary skill in the art. The above references are also not intended to limit the flow restrictor and drill assembly as disclosed herein.

SUMMARY OF THE DISCLOSURE

In a first aspect there is disclosed a flow restrictor comprising a body adapted to restrict a flow of fluid through a drill rod passage, the body having a coupling for coupling said body into the drill rod passage, said body defining an upstream fluid receiving passage, a downstream fluid egress passage, and a passage of restrictive diameter between said passages to limit the flow of fluid in the drill rod passage. In one embodiment, said passages are concentrically aligned with one another along a central longitudinal axis of the drill rod passage.

In one embodiment, the passage of restrictive diameter may vary in diameter from, but is not limited to, a range of about 25% to about 50% of the diameter of the drill rod passage. In one form, the passage of restrictive diameter has a circular cross-section.

In one embodiment, the upstream fluid receiving passage inwardly tapers from an upstream end thereof to the passage of restrictive diameter. In one form, the upstream end of said passage has a diameter greater than, though not limited to, about 60% of the diameter of the drill rod passage.

In one form, the downstream end of the flow restrictor is adapted to receive a rotary drive tool, such as a screw driver, to screw the flow restrictor into the passage. In one embodiment, the downstream fluid egress passage has a polygonal cross-section. In one form, the polygonal cross-section may be hexagonal, star-shaped, square, or a rectangular slot. It will be appreciated that the flow restrictor may be driven into the drill rod passage by engaging the downstream fluid egress passage with the rotary drive tool having a complementary shaped head. In one form, the downstream fluid egress passage is of similar diameter to the upstream end of the upstream fluid receiving passage.

In one embodiment, the coupling is a threading disposed on an external surface of the body, wherein the coupling is configured to complement a threading on an internal wall of the drill rod defining the passage therethrough.

In a second aspect, there is disclosed a flow restrictor comprising a body adapted to restrict a flow of fluid through a drill rod passage, the body having an interior passage to enable fluid flow through the body and an external threading arranged to engage an internal thread disposed within the passage of the drill rod, said restrictor being configured in use to be disposed inboard of an end of the drill rod so as to allow connection of a drill bit to said drill rod end with a threaded stem of said drill bit engaging said internal thread of said drill rod.

In one form, a downstream end of the flow restrictor is adapted to receive rotary drive tool, such as a screw driver, to screw the flow restrictor into the passage. In one form, the downstream end has a polygonal cross-section. In one form, the polygonal cross-section may be hexagonal, star-shaped, square, or a rectangular slot.

In a third aspect of the disclosure, there is provided a drill rod assembly comprising a drill rod having a drill rod passage for passing a flow of fluid therethrough, and a flow restrictor disposed within the drill rod passage and comprising a body adapted to restrict a flow of fluid through the drill rod passage.

In one form, the flow restrictor body has a coupling for coupling said body to the drill rod passage. In one form, the body has an external threading arranged to engage an internal thread disposed within the passage of the drill rod.

In one form, the restrictor is disposed inboard of an end of the drill rod and the drill rod includes a coupling at said drill rod end to engage with a drill bit to connect the drill bit to said drill rod. In one form, the drill rod coupling is part of an internal thread of said drill rod to which the flow restrictor is attached.

In one form, said flow restrictor body defines an upstream fluid receiving passage, a downstream fluid egress passage, and a passage of restrictive diameter between said passages to limit the flow of fluid in the drill rod passage or port means of the drill bit.

In a further aspect, the disclosure provides a drill bit arrangement having a shank adapted to be closely engaged by a drill rod, said drill bit having at least one drill bit passage therein capable of communicating with a drill rod passage of said drill rod to receive a flow of fluid therefrom, said drill bit further comprising a flow restrictor comprising a body adapted to restrict a flow of fluid from said drill rod passage in, or entering, the drill bit passage.

In one form, the drill bit and flow restrictor are integrally formed, or connected to, together. In another form, the drill bit and flow restrictor are separately formed and are arranged to individually be connected to the drill rod.

In one form, the flow restrictor is arranged to be disposed adjacent to the drill bit so as to regulate the flow of fluid entering the drill bit passage. In another form, the flow restrictor is inserted in the drill bit passage. In either form, the flow restrictor may be arranged be fitted as a separate operation so as to allow an operator to modify the flow requirements of a drill assembly either on site or after manufacture o the drill bit or drill rod.

In one form, the flow restrictor is as otherwise described above in accordance with the earlier aspects of the disclosure

Embodiments disclosed allow a reduction in the volume and flow of water delivered to the drill bit, whilst enable effective performance of drilling operations, and consequently allows a reduction in the flow of water generated during drilling operations. A further advantage of embodiments of the disclosure is that a flow restrictor can be retrofitted to exiting drilling assemblies without requiring any modification to the drill rod and/or drill bits.

BRIEF DESCRIPTION OF THE FIGURES

Notwithstanding any other forms which may fall within the scope of the disclosure as set forth in the Summary, specific embodiments will now be described, by way of example only, with reference to the accompanying drawings in which:

FIG. 1 is a perspective view of a flow restrictor in accordance with one specific embodiment;

FIG. 2 is a plan view of the flow restrictor shown in FIG. 1;

FIG. 3 is a longitudinal cross-sectional view of the flow restrictor, taken along line A-A of FIG. 2;

FIG. 4 is an upper plan view of a drilling rod assembly in accordance with one specific embodiment;

FIG. 5 is a longitudinal cross-sectional view of the drilling rod assembly, along line B-B of FIG. 4;

FIG. 6 is an exploded view of the drilling rod assembly shown in FIGS. 4 and 5;

FIG. 7 is a longitudinal section of a drilling assembly including the flow restrictor of FIG. 1; and

FIG. 8 is variation of the drilling assembly of FIG. 8.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

The description broadly relates to a flow restrictor adapted to restrict a flow of fluid, such as water, through a drill rod passage, a drill bit, and a drilling rod assembly.

Referring to FIGS. 1 to 3 there is shown one embodiment of a flow restrictor 10. The flow restrictor 10 comprises a body 12 in the form of a cylindrical section 14 that is configured to be received in a substantially water-tight fit in a drill rod passage 16 of a drill rod 34 as shown in FIGS. 4 to 6. The cylindrical section 14 has an upstream side 18 and a downstream side 20 (oriented on the general direction of flow of fluid through the drill rod 34. The flow restrictor includes a coupling arrangement to connect the restrictor to the drill rod, which in the illustrated form is formed as a threading on the surface 22 of the cylindrical section 14 to facilitate engagement of the flow restrictor 10 with a complementary threaded internal passage 24 of the drill rod passage 16.

In the form as illustrated, the body 12 defines a series of concentrically aligned passages therethrough in the form of an upstream fluid receiving passage 26, a downstream fluid egress passage 28, and a passage 30 of restrictive diameter between said passages 26, 28. The passages 26, 28, 30 are arranged, in use, to be disposed along a central longitudinal axis of the drill rod passage 16.

The upstream fluid receiving passage 26 directs fluid flow from the drill rod passage 16 to the passage 30 of restrictive diameter of the flow restrictor 10. The upstream fluid receiving passage 26 inwardly tapers from an upstream end 32 located at the upstream side 18 of the cylindrical section 14 to the passage 30 of restrictive diameter. It will be appreciated, therefore, that the upstream end 32 has a greater diameter than the passage 30 of restrictive diameter. In some forms of the flow restrictor 10, the upstream end 32 of said passage 26 may have a diameter greater than about 60% of the diameter of the drill rod passage 16. Generally, the diameter of the upstream end 32 of said passage 26 will be marginally narrower than an internal diameter of the drill rod. The upstream fluid receiving passage 26 may extend to about 50% of a total length of the flow restrictor 10.

The passage 30 of restrictive diameter is configured to restrict the flow of fluid in the drill rod passage 16 without reducing the performance of the drill bit. The performance of the drill bit will be diminished if insufficient flow of fluid is available to pass around the drill bit and flush drill cuttings therefrom. In some forms of the flow restrictor 10, the passage 30 is cylindrical with a circular cross-section. The restrictive diameter may vary from about 25% to about 50% of the diameter of the drill rod passage 16, although a restrictive diameter outside this range may be selected depending on the desired drill performance characteristics and the degree of water flow reduction required.

The downstream fluid egress passage 28 directs fluid flow from the flow restrictor 10, in particular from the passage 30 of restrictive diameter, to the drill rod passage 16. In In the form, shown, the downstream fluid egress passage 28 has a constant cross-sectional diameter along its length which is greater than the restrictive diameter of passage 30. In one form of the flow restrictor 10, the passage 28 is of similar diameter to the upstream end of the 32 of the upstream fluid receiving passage 26.

It is to be appreciated that the internal passage(s) in the flow restrictor may be other than described above and illustrated. For example the angle of the tapered upstream fluid receiving passage 26 as well as the passage 30 of restrictive diameter may vary due to manufacturing procedures and different flow needs.

In the flow restrictor 10 shown in the Figures, the downstream fluid egress passage 28 has a hexagonal cross-section. It will be appreciated, however, that the downstream fluid egress passage 28 may have alternatively shaped polygonal cross-sections, such as in the form of a multi-sided star, square, or rectangular. Advantageously, a complementary shaped head of an internal wrenching drive means may be received in said passage 28 to facilitate engagement of the flow restrictor 10 in the drilling rod passage 16, as shown in FIGS. 4-6, by screwing the body 12 of the flow restrictor 10 into the threaded internal wall 24 of the drilling rod passage 16.

In this way, the flow restrictor 10 may be conveniently screwed into the drilling rod passage 16 with the wrenching drive means, and may be later removed therefrom in the same manner.

A further feature of the flow restrictor 10 as illustrated is that it designed to be located in the internal thread 24 in the drill rod which is used to couple a drill bit to the rod. In particular the body of the flow restrictor is designed to be sufficiently thin to locate in the internal passage of drill rods whilst still allowing sufficient exposed internal thread to receive the drill bit. In use, the internal thread is typically designed about 13 mm longer than the shank of the drill bit and it is this excess thread that in the illustrated form is used to accommodate the flow restrictor 10. In this way the flow restrictor can be easily retrofitted to existing drilling assemblies.

FIG. 7 illustrates the drilling assembly including the flow restrictor 10, installed within the drill rod 34. A drill bit 40 having a body 42 and shank 44 is installed on the drill rod 34. In the illustrated form, the shank 44 of the drill bit is threaded and matches the internal thread 24 of the drill rod, the shank length approximates the free length 46 of the internal thread after the flow restrictor is installed such that the positioning of the flow restrictor 10 does not impede normal connection of the drill bit to the drill rod.

The drill bit includes an internal passage 48 that is in fluid communication with the drill rod passage 16 and the flow restrictor, by reducing the diameter of the passage 16, restricts the flow into the drill bit passage 48. As can be seen the narrowest portion of the flow restrictor passage (the central portion 30) is narrower than the diameter of the drill bit passage so that flow restrictor reduces the flow through the drill rod 16 to a greater extent that any restriction to flow that may occur by installation of the drill bit on the drill rod.

EXAMPLES

A non-limiting example of a method employing the flow restrictor 10 of FIGS. 1 to 3 will now be described to illustrate how the flow restrictor 10 may be applied, for example, to drilling operations in respect of coal mining.

Four flow restrictors 10 with respective passages 30 of varying restrictive diameters were trialled to determine the effectiveness of water flow reduction on the performance of a drill bit and the consequent reduction of residual water in the roadway in the drilling vicinity. Visual observations were made with regard to whether there was a positive or negative effect on the extent of flushing the hole being drilled.

The drill rod used in the trial had a drill rod passage diameter of 12.7 mm and the drill bit had a corresponding diameter of 7 mm. The flow rate of water through the drill rod passage where a flow restrictor 10 was not used was 35 L/min.

The Table shows the effect of the respective passages 30 of varying restrictive diameters on the flow rate and flushing effect.

	TABLE
	Diameter (mm) of Passage 30
	3.1	4.7	5.6	6.3
Flow (L/min)	13	19	28	27
Flushing Effect	Negative	Negative	No discernable	No discernable
			effect	effect

Each of the four flow restrictors 10 used in the trial decreased the flow rate of water through the drill rod passage 16 while still providing a flushing effect. No blockages of the drill bit were encountered during the trial and accordingly were effective in providing flushing to the cutting face.

Based on the trials, the 5.6 and 6.3 holes were considered to exhibit less than ideal reduction in flow rates. Whilst the 3.1 hole showed the most significant reductions in flow rate (down from 35 L/min to 13 L/min) there was concern that in commercial operation in some strata, the passage may become blocked. Accordingly the preferred configuration from the trial was the 4.7 hole which provided a reduction in flow rate of 16 L/min (from 35 L/min to 19 L/min). This configuration provided a high percentage reduction in flow rate whilst considered to be less likely to become blocked.

Numerous variations and modifications will suggest themselves to persons skilled in the relevant art, in addition to those already described, without departing from the basic inventive concepts. All such variations and modifications are to be considered within the scope of the present invention, the nature of which is to be determined from the preceding description.

For example, it will be appreciated that the flow restrictor 10 may be readily adapted for incorporation with a drill bit to restrict the flow of fluid entering the drill bit from the drill rod passage or may even be incorporated within the drill bit itself. In one form, the flow restrictor of this variation may be retrofitted into the drill bit by being screwed or pressed into an internally threaded or otherwise formed cavity within the drill bit. Such an arrangement of a removable flow restrictor 100 inserted in the drill bit 60 is shown in FIG. 8. In the illustrated form the flow restrictor 100 is screw threaded into a purpose designed internal threading 62 in the drill bit shank 64 of the drill bit.

In the claims which follow, and in the preceding description, except where the context requires otherwise due to express language or necessary implication, the word “comprise” and variations such as “comprises” or “comprising” are used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the apparatus and method as disclosed herein.

Claims

1. A flow restrictor comprising a body adapted to restrict a flow of fluid through a drill rod passage, the body having a coupling for coupling said body into the drill rod passage, said body defining an upstream fluid receiving passage, a downstream fluid egress passage, and a passage of restrictive diameter between said upstream and downstream fluid passages to limit the flow of fluid in the drill rod passage.

2. The flow restrictor according to claim 1, wherein said passages are concentrically aligned with one another along a central longitudinal axis of the drill rod passage.

3. The flow restrictor according to claim 1, wherein the passage of restrictive diameter has a diameter from about 25% to about 50% of the diameter of the drill rod passage.

4. The flow restrictor according to claim 1, wherein the passage of restrictive diameter has a circular cross-section.

5. The flow restrictor according to claim 1, wherein the upstream fluid receiving passage inwardly tapers from an upstream end thereof to the passage of restrictive diameter.

6. The flow restrictor according to claim 5, wherein the upstream end of said passage has a diameter greater than about 60% of the drill rod passage.

7. The flow restrictor according to claim 1, wherein the downstream fluid egress passage has a polygonal cross-section.

8. The flow restrictor according to claim 7, wherein the polygonal cross-section is hexagonal, star-shaped, square, or a rectangular slot.

9. The flow restrictor according to claim 7, wherein the polygonal cross-section is adapted to receive a complementary shaped head of a rotary drive

10. The flow restrictor according to claim 5, wherein the downstream fluid egress passage has a similar diameter to the upstream end of the upstream fluid receiving passage.

11. The flow restrictor according to claim 1, wherein the coupling is a threading disposed on an external surface of the body, the threading being complementary to a threading on an internal wall of the drill rod defining the passage therethrough.

12. A flow restrictor comprising a body adapted to restrict a flow of fluid through a drill rod passage, the body having an interior passage to enable fluid flow through the body and an external threading arranged to engage an internal thread disposed within the drill rod passage, said restrictor being configured in use to be disposed inboard of an end of the drill rod so as to allow connection of a drill bit to said drill rod end with a threaded stem of said drill bit engaging said internal thread of said drill rod.

13. A drill rod assembly comprising a drill rod having a drill rod passage for passing a flow of fluid therethrough, and a flow restrictor disposed within the drill rod passage and comprising a body adapted to be restrict a flow of fluid through the drill rod passage.

14. A drill rod assembly according to claim 13, wherein the flow restrictor is disposed inboard of an end of the drill rod and the drill rod includes a coupling at said drill rod end to engage with drill bit to connect the drill bit to said drill rod.

15. A drill bit arrangement having a shank adapted to be closely engaged by a drill rod, said drill bit having at least one internal passage therein capable of communicating with a drill rod passage of said drill rod to receive a flow of fluid therefrom, said drill bit further comprising a flow restrictor comprising a body adapted to restrict a flow of fluid from said drill rod passage in, or entering, the drill bit passage.

16. A drill bit arrangement according to claim 15, wherein the flow restrictor is formed separate to the drill bit and is coupled to the drill bit.

17. A drill bit arrangement according to claim 16, wherein the flow restrictor is disposed within the drill bit passage.

18. (canceled)

19. (canceled)