Field of the Invention The present invention relates to a core sampling system for retrieving core material samples, typically by drilling into the ground.

Background of the Invention In conventional core drilling, an annular drill bit connected to an end of a string of drill rods creates a hole as the drill string rotates, and as the drill bit advances core material is received into an internal drill rod space defined inside the drill string.

In some such core drilling systems, an inner tube assembly is disposed inside the drill string, and serves to receive core material and provide a degree of protection for the core material from the rotating drill string.

In order to retrieve a core sample, the inner tube assembly containing the core sample is typically retrieved from the hole by deploying an overshot coupled to a wireline into the internal drill rod space and engaging the overshot with the inner tube assembly.

During the drilling process, drilling fluid is supplied to a region adjacent the drill bit through the drill string. However, this arrangement for drilling and retrieving core samples is relatively complex and time consuming.

Summary of the Invention In accordance with a first aspect of the present invention, there is provided a core sampling system comprising:

at least one hollow drill rod, each drill rod arranged to be connected endwise to an adjacent drill rod so as to define a string of drill rods that define an internal drill rod space for receiving core material during drilling;

an annular drill bit connected to a free end of an end most drill rod; and a fluid inlet member arranged such that when the core sampling system drills a hole the fluid inlet member is in fluid communication with an annular space defined between the at least one drill rod and the hole, the annular space in fluid

communication with the drill bit and thereby the internal drill rod space; and

a core breaking device arranged to effect fracturing of core material received in the internal drill rod space from surrounding ground material;

the fluid inlet member arranged to receive drilling fluid and to direct the received drilling fluid to the annular space and subsequently to the drill bit and the internal drill rod space, thereby urging fractured core material in the internal drill rod space to move through the internal drill rod space towards the fluid inlet member. In an embodiment, the fluid inlet member includes a collar member disposed around a drill rod, the collar member capable of forming a seal with the drill rod.

In an embodiment, the collar member includes a valve arranged to facilitate control of flow of drilling fluid through the collar member to the annular space.

The core breaking device may include at least one protrusion arranged to extend inwardly of the internal drill rod space, the at least one protrusion contacting the core material received in the internal drill rod space and urging the core material to move towards an internal surface of the at least one drill rod, thereby causing a fracturing force to be exerted on the core material received in the internal drill rod space.

In an embodiment, the core breaking device includes one protrusion.

In an alternative embodiment, the core breaking device includes a plurality of protrusions. The plurality of protrusions may be disposed such that a first protrusion contacts the core material received in the internal drill rod space and urges the core material to move towards an internal surface of the at least one drill rod, and as the first protrusion wears, a subsequent protrusion contacts the core material received in the internal drill rod space and urges the core material to move towards an internal surface of the at least one drill rod.

In an embodiment, at least one protrusion is substantially wedge shaped. In an embodiment, at least one protrusion is substantially hemispherical.

In an embodiment, the at least one protrusion is formed of hardened steel and/or hardened material having a composite diamond coating. In an embodiment, the system includes a sample pipe arranged to receive core material from the at least one drill rod. The system may include a swivel device arranged to facilitate rotation of the at least one drill rod relative to the sample pipe.

In an embodiment, the system includes a fluid swivel arranged enable fluid to flow into the internal drill rod space during a drilling operation whilst facilitating rotation of the at least one drill rod relative to the sample pipe. In an embodiment, the collar member includes an inflatable member controllably disposable in a deflated configuration and an inflated configuration, wherein the annular space is substantially sealed when the inflatable member is in the inflated configuration. In an embodiment, the collar member includes a packer and a seal arranged to seal the annular space whilst facilitating rotation of the at least one drill rod.

In an embodiment, the drill bit includes at least one bit aperture arranged to facilitate passage of fluid from the annular space to the internal drill rod space.

In accordance with a second aspect of the present invention, there is provided a method of obtaining a core sample, the method comprising:

connecting an annular drill bit to a free end of at least one hollow drill rod, each drill rod arranged to be connected endwise to an adjacent drill rod so as to define a string of drill rods having an internal drill rod space for receiving core material during drilling;

providing a fluid inlet member arranged such that when the drill bit drills a hole the fluid inlet member is in fluid communication with an annular space defined between the at least one drill rod and the hole, the annular space in fluid communication with the drill bit and thereby the internal drill rod space;

drilling a hole using the annular drill bit and connected at least one drill rod; and effecting fracturing of core material from surrounding ground material as the core material is received in the internal drill rod space during drilling;

providing drilling fluid to the fluid inlet member so as to direct the received drilling fluid to the annular space and subsequently to the drill bit and the internal drill rod space, thereby urging fractured core material in the internal drill rod space to move along the internal drill rod space towards the fluid inlet member. In an embodiment, the method comprises:

causing drilling fluid to flow to the annular space and subsequently to the internal drill rod space during drilling; and

controlling the flow of drilling fluid to the annular space and subsequently to the internal drill rod space so as to thereby control retrieval of core material.

The method may comprise controlling retrieval of core material so that the core material is retrieved continuously or periodically, for example by controlling the fluid pressure of the drilling fluid.

In an embodiment, the method comprises:

causing drilling fluid to flow through the internal drill rod space and

subsequently to the annular space during drilling; and

controlling the flow of drilling fluid to the annular space and subsequently to the internal drill rod space so as to retrieve core material.

Brief Description of the Drawings The present invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a diagrammatic representation of a core sampling system in accordance with an embodiment of the present invention;

Figure 2 is a diagrammatic cross sectional view of a collar member of the system shown in Figure 1 ;

Figure 3 is diagrammatic representation of the core sampling system shown in Figure 1 during a core retrieval process;

Figure 4 is a diagrammatic cross-sectional representation of the core sampling system shown in Figure 1 during a core retrieval process;

Figure 5 is a diagrammatic cross-sectional view of a drill bit end of a drill string, including a core breaking device;

Figure 6 is a diagrammatic perspective view of a core breaking device according to an embodiment of the present invention;

Figure 7 is a diagrammatic perspective view of a core breaking device according to an alternative embodiment of the present invention;

Figure 8 is a diagrammatic perspective view of a core breaking device according to a further alternative embodiment of the present invention; Figures 9a to 9d illustrate a process of breaking a core using the core sampling system shown in Figure 1 ; and

Figure 10 is a diagrammatic cross sectional view of an alternative collar member for use with a core sampling system according to an alternative embodiment of the present invention.

Description of an Embodiment of the Invention

Referring to the drawings, Figures 1 to 4 show a core sampling system 10 that includes a plurality of drill rods 12 connected endwise to each other so as to define a string of drill rods that at least partially define an internal drill rod space 13. Connected to a free end of the string of drill rods 12 is a drill bit 14 of generally annular configuration. The string of drill rods 12 and the drill bit 14 are configured such that when the drill rods 12 and drill bit 14 rotate about a longitudinal axis, a hole 16 is formed, in this example in the ground 18, with core material being progressively received in the internal drill rod space 13 as the drill bit moves progressively deeper into the ground 18.

In this example, as shown in Figure 1 , during drilling a fluid swivel 21 is connected to the drill rods 12 so that drilling fluid is provided to the internal drill rod space 13 from a pump 22 to wash cuttings away from the drill bit 14 and keep the drill bit 14 cool, whilst permitting rotation of the drill rods 12.

Connected to a drill rod 12 at a hole entrance 19 is a fluid inlet member, in this example a collar member 20, arranged, during a core retrieval process, to receive drilling fluid from the pump 22 and direct the drilling fluid through an annular space 23 defined between the string of drill rods 12 and the hole 16 to the drill bit 14 disposed at the bottom of the hole, as shown in Figure 4. The collar member 20 is capable of forming a seal with the hole 16 and the drill rod 12 to which it is connected, as discussed in more detail below.

As shown in Figures 3 and 4, during a core retrieval process, a sample pipe 24 is connected to the drill rods 12 through a swivel 25 so as to receive samples of core material during use and supply the core material to a core collector 26. During core sample retrieval, the drilling fluid introduced into the annular space 23 is able to flow into the internal drill rod space 13 and passage of fluid in this way from the annular space to the internal drill rod space 13 is enhanced by bit apertures 28 formed on the drill bit 14.

In this example, the drill bit 14 has an internal diameter configured such that the core material produced by drilling is a relatively tight fit inside the drill rods 12.

The sample pipe 24 in this example is formed of PVC material, although it will be understood that any suitable material is envisaged. The sample pipe 24 may feed into a fluid collector (not shown) having an outlet valve that facilitates recycling of the drilling fluid back to the collar member 20. However, it will be understood that any suitable arrangement for facilitating recycling of drilling fluid whilst enabling collection of core material is envisaged.

Figure 2 shows the collar member in more detail. The collar member 20 includes a fluid inlet 40 for receiving drilling fluid to be directed by the collar member 20 to the annular space 23. As shown in Figure 4, the collar member 20 is disposed at the hole entrance 19.

By controlling the amount of drilling fluid and the drilling fluid pressure that is transferred through the fluid inlet 40 to the annular space 23 and thereby the core material in the drill rods 12, it is possible for an operator to control retrieval of core material. For example, by controlling the flow of drilling fluid, it is possible to control whether core material is continuously retrieved or periodically retrieved at controlled intervals. The collar member 20 also includes an inflatable bladder 50 disposable in an inflated configuration and a deflated configuration and arranged such that when the bladder 50 is in the inflated configuration the annular space 23 between the drill rods 12 and the hole 16 is substantially sealed at the collar member 20. In order to facilitate controlled retrieval of core samples, the core sampling system 10 includes a core breaker 70, as shown more particularly in Figure 5. The core breaker 70 is housed in a blank tube or reamer 72 engaged with and disposed between the drill bit 14 and a drill rod 12, for example by screw threadably engaging with the drill bit 14 and the drill rod 12. The core breaker 70 includes at least one protrusion 74 arranged to cause core material received in the internal drill rod space 13 to fracture, thereby enabling retrieval of more manageable core sample pieces from the drill string. As shown in Figure 5, the core breaker 70 may comprise an annular body 76 integral with an arcuate portion 78 on which one protrusion 74 is disposed. The protrusion 74 in this example is of tapered configuration such that, during drilling, the core sample is urged to move in a direction away from the arcuate portion 78 as a core sample is progressively received in the internal drill rod space 13, ultimately causing the core sample to fracture.

An alternative core breaker 80 is shown in Figure 7. Like and similar features are indicated with like reference numerals.

The alternative core breaker 80 includes multiple protrusions 74 that are successively used to urge a core sample to move away from the arcuate portion 78 and thereby fracture as each protrusion becomes worn during use. A further alternative core breaker 90 is shown in Figure 8. Like and similar features are indicated with like reference numerals.

The alternative core breaker 90 includes multiple protrusions 92 of substantially hemispherical configuration that are successively used to urge a core sample to move away from the arcuate portion 78 and thereby fracture as each protrusion becomes worn during use.

The core breaker 70, 80, 90 may be formed of any suitably strong, hard material, and in this example the core breaker 70, 80, 90 is formed of hardened steel and/or hardened material with a composite diamond coating layer on surfaces that are subject to wear during use. However, it will be understood that any suitable material is envisaged.

Fracturing of a core sample received during use in the internal drill rod space 13 is shown diagrammatically in Figures 9a to 9d. For simplicity, only a drill rod 12 and a protrusion 74 are shown.

As shown in Figure 9a, as drilling progresses, a core sample 94 is progressively received in the drill rod 12, and when an end 96 of the core sample reaches the protrusion 74 of the core breaker 70, the end 96 of the core sample 94 is urged to move in a direction away from an internal surface of the drill rods 12 at a first location 98 adjacent the protrusion 74 and towards the internal surface of the drill rods 12 at a second location 100 opposite to the first location 98. As drilling progresses, the end 96 of the core sample 94 moves progressively further into the drill rod 12.

Typically, the core sample 94 will fracture as a result of the movement of the core sample before the core sample 94 contacts the internal surface of the drill rods 12. However, if this does not occur, as a consequence of contact with the internal surface of the drill rods, force is progressively increasingly applied to the end 96 of the core sample 94 and to a portion of the core sample 94 adjacent the protrusion 74 in opposite directions, which ultimately causes the core sample 94 to fracture, as shown in Figure 9d.

It will be understood that the length of the core sample 94 when fracture occurs can be encouraged to occur at a desired length by defining the maximum height of the protrusion above the internal surface of the drill rod 12. Accordingly, by increasing the height of the protrusion 74, the core sample can be encouraged to fracture earlier, and with a length that is relatively shorter, than would occur with a protrusion of shorter height.

During use, as shown in Figure 1 , operators of the core sampling system 10 engage the collar member 20 with a hole entrance 19, engage the drilling fluid swivel 21 with an upper end of the drill rods 12, connect the drilling fluid swivel to the pump 22, and commence drilling so as to form a hole 16, for example in the ground 18. As drilling progresses, drilling fluid is pumped through the fluid swivel 21 and into the internal drill rod space 13 towards the drill bit 14 to cool the drill bit 14 and wash away cuttings from the drill bit 14.

During a drilling operation, the bladder 50 of the collar member 20 is disposed in the deflated configuration so that drilling fluid that has been pumped through the internal drill rod space 13 to the drill bit 14 is able to flow through the annular space 23, past the collar member 20, and away from the hole 16. As drilling progresses, a core sample 94 is progressively received in the internal drill rod space 13, and is caused to fracture when the length of the core sample 94 is such that forces on the core sample 94 between the protrusion 74 and an end 96 of the core sample 94 become sufficiently large.

As shown in Figures 3 and 4, when it is desired to remove fractured core material samples from the internal drill rod space 13, for example when approximately 3m of drilling has been carried out, operators of the core sampling system 10 replace the fluid swivel 21 with the swivel 25, connect the sample pipe 24 to the swivel 25, and connect the pump 22 to the fluid inlet 40 of the collar member 20. The operators then inflate the bladder 50 to seal the annular space 23, and cause fluid to flow from the pump 22, as shown by arrow A, through the fluid inlet 40 to the annular space 23. Since the annular space 23 is sealed by the bladder 50, the drilling fluid flows through the collar member 20 and travels in a direction shown by arrow B from the collar member 20 towards the drill bit 14, into the internal drill rod space 13, as indicated by arrows C, and upwardly of the internal drill rod space 13 from the drill bit 14 towards the core collector 26, as indicated by arrows D.

In this way, fractured core samples received in the internal drill rod space 13 are urged by the drilling fluid to move through the internal drill rod space 13 towards the core collector 26, thereby facilitating retrieval of the core samples.

In an alternative core sampling system, instead of causing drilling fluid to flow down through the drill rods 12 during drilling, then reversing the fluid flow direction during core retrieval to cause the drilling fluid to flow through the annular space 23 and up through the drill rods 12, the system may be arranged such that drilling fluid flows through the annular space 23 and up through the drill rods 12 during both drilling and core retrieval.

For this purpose, the system according to this embodiment is configured according to the arrangement shown in Figures 3 and 4, and the system may include an alternative collar member 1 10, as shown in Figure 10. Like and similar features are indicated with like reference numerals.

The collar member 1 10 includes a packer 1 12 and a seal 1 14 that serve to seal the annular space 23 whilst permitting the drill rods 12 to rotate during drilling.

During use, drilling fluid is pumped through the annular space 23 towards the drill bit 14 to cool the drill bit 14 and wash away cuttings from the drill bit 14 up through the internal drill rod space 13. As drilling progresses, a core sample 94 is progressively received in the internal drill rod space 13, and is caused to fracture when the length of the core sample 94 is such that forces on the core sample 94 between the protrusion 74 and an end 96 of the core sample 94 become sufficiently large. Either continuously by virtue of the upwards fluid flow through the drill rods 12, or by increasing the fluid pressure of the fluid flow at defined intervals, fractured core material samples are caused to move upwards through the drill rods 12 from the drill bit 14 towards the core collector 26.

It will be appreciated that by drilling without using an inner tube assembly, causing the core samples to fracture as drilling progresses, and using the drilling fluid to retrieve the fractured core samples, a continuous core drilling system is achieved that is simpler and faster that core sampling systems known hitherto that use inner tube assemblies and require a wireline to retrieve core samples.

In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word "comprise" or variations such as "comprises" or "comprising" is 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 invention.

It is to be understood that, if any prior art publication is referred to herein, such reference does not constitute an admission that the publication forms a part of the common general knowledge in the art, in Australia or any other country.

Modifications and variations as would be apparent to a skilled addressee are deemed to be within the scope of the present invention.