A drilling apparatus and a method for controlling a drilling apparatus

Abstract

A drilling apparatus comprising a drill string, a drill head, and a sealing arrangement formed around the drill string. The sealing arrangement and the drill string are movable relative to one another. The sealing arrangement comprises: a radial sealing element, configured to seal between the sealing arrangement and the drill string, a covering body, formed around the drill string and defining a cavity therethrough, with an opening at an end portion. The covering body comprising: an axial sealing element configured to seal the cavity such that it forms a first volume delimited by the covering body and the mineral substrate. The drilling apparatus comprises a fluid transfer arrangement comprising a first fluid channel in fluid communication with a volume containing the drill head when the sealing arrangement forms the first volume, and a second fluid channel in fluid communication with the first volume.

Description

[0001] A DRILLING APPARATUS AND A METHOD FOR CONTROLLING A DRILLING APPARATUS

[0002] TECHNICAL FIELD

[0003] The present disclosure concerns a drilling apparatus. The invention also concerns a method for controlling said drilling apparatus. The disclosed drilling apparatus and method may for example be applied in rock drilling, surface drilling, and blast hole drilling operations.

[0004] BACKGROUND

[0005] During rock drilling it is often necessary to supply a fluid towards the mineral substrate. Supply of fluid may be necessary to flush a drilled hole, to provide cooling, or may be necessary for the drill type. For example, plasma drilling electrodes must be submerged in a liquid. When a fluid is to be supplied for a drilling operation it is advantageous to contain the fluid such that fluid loss is mitigated. It is known to prepare the drill site to prevent such fluid loss, by lining the hole for example. However, for example, for operations where the drill site is temporary, such as in blast hole drilling, or when there is insufficient time for preparations, this may not be possible.

[0006] It is therefore a need to develop improved technology relating to rock drilling.

[0007] SUMMARY

[0008] A primary objective of the present disclosure is to achieve an in at least some aspect improved drilling apparatus, drill rig and / or method. For example, it is an objective to achieve a drilling apparatus whereby a fluid can be sealed at the drill site which at least partially alleviates the drawbacks associated with prior art methods, such as long preparation and installation times.

[0009] According to a first aspect of the disclosure, at least the primary object is achieved by an apparatus according to claim 1. Hence, there is provided a drilling apparatus comprising a drill string, extending along a central axis, a drill head, located at an end of the drill string and configured to break a mineral substrate, a sealing arrangement, formed around the central axis of the drill string, wherein the sealing arrangement and the drill string are movable relative to one another, the movement being directed along the central axis of the drill string, the sealing arrangement comprising a radial sealing element, configured to seal between the sealing arrangement and the drill string, a first covering body, formed around the central axis of the drill string, and defining a first cavity therethrough, with a first opening at an end portion of the first covering body for the drill head, the first covering body comprising a first axial sealing element associated with the first opening and configured to seal the first cavity towards the mineral substrate when the sealing arrangement is positioned such that it forms a first volume located at least partly inside the first cavity and delimited by at least the first covering body and the mineral substrate, wherein the drilling apparatus comprises a fluid transfer arrangement, the fluid transfer arrangement comprising a first fluid channel in fluid communication with a volume containing the drill head when the sealing arrangement forms the first volume, and a second fluid channel in fluid communication with the first volume.

[0010] By providing a drilling apparatus having a sealing arrangement whereby the sealing arrangement and drill string are movable relative to one another it is possible to move the sealing arrangement relative to the drill string such that sealing may be ensured, and / or to move the drill string relative to the sealing arrangement such that a distance between the drill head and the mineral substrate may be adjusted whilst maintaining the sealing arrangement in sealing engagement with the mineral substrate. Furthermore, by having a first fluid channel in communication with a volume containing the drill head, and a second fluid channel in communication with a first volume formed by the first covering body and the mineral substrate it is possible to remove and supply fluid whilst maintaining the sealing arrangement in sealing engagement with the mineral substrate.

[0011] Optionally, the fluid comprises a flushing fluid, wherein the flushing fluid comprises a liquid. The liquid may comprise water, an oil, or mixture of liquids, such as an oil-water emulsion. It could be advantageous to use a biopolymer oil, or any biodegradable oil. The liquid may contain impurities, for example the liquid may comprise saline water. By providing a flushing fluid comprising a liquid to the volume containing the drill head, as opposed to a gas, the removal of cuttings may be improved due to a higher viscosity, improved cooling may also be achieved, and it may be possible to use specific drilling means, such as plasma drilling whereby electrodes must be submerged in a liquid. Optionally, the drilling equipment comprises a drill head having at least two electrodes, a pulsed power generator for generating high voltage current pulses, whereby the drill head breaks the mineral substrate and forms a hole in the mineral substrate, by passing a high voltage current pulse generated by the pulsed power generator between the at least two electrodes via the mineral substrate.

[0012] Optionally, the fluid transfer arrangement comprises a first pump configured to pump the fluid through the first fluid channel. By providing a first pump fluid transfer to / from the volume containing the drill head may be achieved such that a pressure in the volume containing the drill head may be changed.

[0013] Optionally, the fluid transfer arrangement comprises a second pump configured to pump the fluid through the second fluid channel. By providing a second pump fluid transfer to / from the first volume may be achieved such that a pressure in the first volume may be changed.

[0014] Optionally, the fluid transfer arrangement is configured to generate a pressure in the first volume higher than an atmospheric pressure. By providing a pressure in the first volume higher than an atmospheric pressure the flushing fluid can be directed out of the first volume by a counter pressure.

[0015] Optionally, the fluid transfer arrangement is configured to generate a pressure in the first volume lower than an atmospheric pressure. By providing a pressure in the first volume lower than an atmospheric pressure removal of the flushing fluid may be achieved whilst the risk of escape of flushing fluid past the first axial sealing element can be reduced when the first axial sealing element forms an imperfect seal with the mineral substrate.

[0016] Optionally, the sealing arrangement comprises a second covering body formed around the central axis of the drill string, and defining a second cavity therethrough, with a second opening at an end portion of the second covering body for the drill head, the second covering body comprising a second axial sealing element, associated with the second opening and configured to seal the second cavity towards the mineral substrate when the sealing arrangement is positioned such that it forms a second volume surrounded by the first volume and delimited by the second covering body and the mineral substrate. By providing a second covering body that forms a second volume surrounded by the first volume and delimited by the second covering body, and having a second axial sealing element, fluid loss can be further reduced. Optionally, the fluid transfer arrangement is configured to generate a pressure in the second volume greater than a pressure in the first volume. By providing a pressure in the second volume greater than a pressure in the first volume the fluid may be transferred from the second volume to the first volume via a counter pressure.

[0017] Optionally, the sealing arrangement comprises at least one spring element extending between the first covering body and the second covering body and configured to bias the second covering body towards the mineral substrate. By providing a spring element between the first covering body and the second covering body the sealing of the second covering body towards the mineral substrate may be improved and sealing of the second covering body may be achieved by the positioning of the first covering body.

[0018] Optionally, the drilling apparatus comprises an actuation arrangement configured to move the sealing arrangement along the central axis of the drill string towards the mineral substrate. By providing an actuation arrangement the sealing arrangement may be repositioned along the central axis of the drill string, for example to improve sealing of a volume surrounding the drill head.

[0019] Optionally, the second fluid channel is in fluid communication with the first volume via a hole formed in the first covering body. By providing a second fluid channel in fluid communication with the first volume via a hole formed in the first covering body, fluid may be transferred to / from the first volume.

[0020] Optionally, the first fluid channel and the second fluid channel are in fluid communication with a reservoir and the fluid transfer arrangement is configured to circulate fluid between a volume enclosed by the first volume and the reservoir. By configuring the first fluid channel and the second fluid channel such that they are in fluid communication with a reservoir such that it is possible to recirculate fluid, the same fluid may continuously be used without replacement.

[0021] According to a second aspect of the disclosure, at least the primary object is achieved by a drill rig comprising the drilling apparatus according to the first aspect of the disclosure. According to a third aspect of the disclosure, at least the primary object is achieved by a method of controlling the drilling apparatus according to claim 13. The method comprises adjoining the sealing arrangement with the mineral substrate by moving the sealing arrangement along the central axis of the drill string towards the mineral substrate, supplying a fluid to a volume containing the drill head via the fluid transfer arrangement, controlling a pressure in a volume enclosed by the sealing arrangement by controlling a fluid flow through the fluid transfer arrangement.

[0022] BRIEF DESCRIPTION OF THE DRAWINGS

[0023] With reference to the appended drawings, below follows a more detailed description of embodiments of the disclosure cited as examples.

[0024] Fig. 1 is a schematic diagram of a drill rig according to an embodiment of the disclosure,

[0025] Fig. 2 is a schematic diagram of a drilling apparatus according to a first embodiment of the disclosure,

[0026] Fig. 3a is a side view of a first covering body according to a first embodiment of the disclosure,

[0027] Fig. 3b is a bottom view of a first covering body according to a first embodiment of the disclosure,

[0028] Fig. 3c is a sectional view of a first covering body according to a first embodiment of the disclosure,

[0029] Fig. 4 is a schematic diagram of a drilling apparatus according to a second embodiment of the disclosure,

[0030] Fig. 5 is a schematic view of a drilling apparatus according to a third embodiment of the disclosure,

[0031] Fig. 6a is a side view of a second covering body according to a third embodiment of the disclosure,

[0032] Fig. 6b is a bottom view of a second covering body according to a third embodiment of the disclosure,

[0033] Fig. 6c is a sectional view of a first covering body according to a third embodiment of the disclosure,

[0034] Fig. 7 is a schematic diagram of a sealing arrangement according to a fourth embodiment of the disclosure, Fig. 8 is a flow chart illustrating a method according to embodiments of the disclosure.

[0035] The drawings show diagrammatic, exemplifying embodiments of the present disclosure and are thus not necessarily drawn to scale. It shall be understood that the embodiments shown and described are exemplifying and that the disclosure is not limited to these embodiments. It shall also be noted that some details in the drawings may be exaggerated in order to better describe and illustrate the disclosure. Like reference characters refer to like elements throughout the description, unless expressed otherwise.

[0036] DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0037] Fig. 1 illustrates schematically a drill rig 2 comprising a drilling apparatus 4. The drilling apparatus 4 comprises a drill string 6, extending along a central axis X, and a drill head 8, located at an end of the drill string 6 and configured to break a mineral substrate 10 in the form of a rock. The mineral substrate 10 comprises a ground surface extending substantially in a horizontal plane below the drill rig 2. In alternative embodiments the mineral substrate 10 comprises a surface extending at an angle with respect to a horizontal plane. As the mineral substrate 10 is drilled, a hole 52 is formed in the mineral substrate 10. The hole 52 extends into the mineral substrate 10, whereby the depth of the hole 52 increases as the mineral substrate 10 is broken by the drill head 8. The hole 52 may have a circular cross-section or a square cross-section, or any cross-sectional shape, dependent on how the drill head 8 is configured.

[0038] The drilling apparatus 4 extends along a central axis X, the central axis X of the drilling apparatus 4 extending substantially perpendicular to the mineral substrate 10. In alternative embodiments, the central axis X of the drilling equipment 4 may extend at any inclination to the mineral substrate 10 less than 90°.

[0039] The drill head 8 is configured to break a mineral substrate 10. In the shown example, the drill head 8 comprises two electrodes 54 configured to break the mineral substrate 10 by passing of electric pulses between the two electrodes 54 via the mineral substrate 10, i.e. , by pulsed plasma drilling. The drill head 8 may have more than two electrodes, for example three, four, or five electrodes. In alternative embodiments the drill head 8 comprises, rotary, top-hammer, or down-the-hole drilling means, or any known drilling means, which may be electrically, hydraulically, or pneumatically powered. The drill rig 2 comprises an electrical power supply 56 which will be discussed in detail with Fig. 2. The drill rig 2 further comprises an actuated arm 58. The arm 58 may be actuated by hydraulic, pneumatic, or electrical means, for at least vertical positioning of the drilling apparatus 4, such as in response to signals from one or more position sensors (not shown), or similar, sensing the distance between the drill head 8 and the mineral substrate 10 surface. The drill rig 2 further comprises ground engaging members 60 for moving the drill rig 2 in a direction parallel with the mineral substrate 10.

[0040] Fig. 2 illustrates schematically a drilling apparatus 4 according to an embodiment of the disclosure. The drilling apparatus 4 comprises a sealing arrangement 12 formed around the central axis X of the drill string 6, wherein the sealing arrangement 12 and the drill string 6 are movable relative to one another, the movement being directed along the central axis X of the drill string 6.

[0041] The sealing arrangement 12 comprises a first covering body 16, formed around the central axis X of the drill string 6, and defining a first cavity 18 (see Figs. 3b-3c) therethrough, with a first opening 20 (See Figs. 3b-3c) at an end portion of the first covering body 16 for the drill head 8. The first covering body 16 comprises a first axial sealing element 22 associated with the first opening 20 and configured to seal the first cavity 18 towards the mineral substrate 10 when the sealing arrangement 12 is positioned such that it forms a first volume 24 located at least partly inside the first cavity 18 and delimited by at least the first covering body 16 and the mineral substrate 10. The first covering body 16 will be described in more detail with reference to Fig. 3a-3c.

[0042] The sealing arrangement 12 further comprises a radial sealing element 14, configured to seal between the sealing arrangement 12 and the drill string 6. In the shown embodiment the radial sealing element 14 is associated with the first covering body 16 and is configured to seal the first covering body 16 towards the drill string 6. The radial sealing element 14 may be integrally formed with the first covering body, or alternatively the radial sealing element 14 may comprise a separate component. If the radial sealing element 14 comprises a separate component, said separate component may comprise a different material, for example it may be advantageous to use steel for the covering body and rubber for the radial sealing element 14. The radial sealing element 14 may be joined to the first covering body using any known method. Alternatively, the radial sealing element 14 may remain detached from the first covering body. Alternatively, the first covering body and / or the radial sealing element 14 may be adapted such that they may be fitted together, for example by way of cut-outs, grooves, or the like. In the shown embodiment the radial sealing element 14 comprises a ring-shaped element formed in the innermost top corner of the first covering body. In alternative embodiments the radial sealing element 14 may be located anywhere along the length of the first covering body. In one embodiment the radial sealing element 14 may be located at the top facing surface of the first covering body. Additionally, it may be possible to use multiple radial sealing elements. In the shown embodiment the radial sealing element 14 comprises a square toroid, alternatively the toroid may be formed of a rectangle, circle, triangle, or any shape. It may be advantageous for the radial sealing element 14 to have any number of protrusions (not shown) extending radially towards the drill string 6. Where a number of protrusions are formed the protrusions may be arranged axially and / or circumferentially along the radial sealing element. A protrusion may be formed having a number of radially extending slits, cut-outs, or the like, formed in any shape and / or orientation. It is also possible for the drill string to have any number of sealing elements formed, or attached thereon such that they may seal with the radial sealing element 14, or elsewhere thereto with the first covering body 16.

[0043] The drilling apparatus 4 further comprises a fluid transfer arrangement 26. The fluid transfer arrangement 26 comprises a first fluid channel 28 in fluid communication with a volume containing the drill head 8, when the sealing arrangement 12 forms the first volume 24, and a fluid reservoir 50. In the shown example, the first fluid channel 28 extends through the drill string 6 and forms an outlet at the bottom surface of the drill head 8. Alternatively, the first fluid channel 28 extends only partially through the drill string 6, or the first fluid channel 28 extends outside of the drill string 6. The first fluid channel 28 may extend past the bottom surface of the drill head 8. Additionally, the first fluid channel 28 may form an outlet elsewhere on the drilling apparatus 4, for example on the side of the drill head 8, or above the drill head 8 through the drill string 6. The fluid transfer arrangement 26 further comprises a second fluid channel 30 in fluid communication with the first volume 24 and the reservoir 50. The second fluid channel 30 extends outside of the drill string 6. In alternative embodiments the second fluid channel 30 may extend at least partially through the drill string 6. In the shown embodiment the first volume 24 and the volume containing the drill head 8 are one and the same, as such both the first fluid channel 28 and the second fluid channel 30 are in fluid communication with the first volume 24.

[0044] The fluid may comprise a flushing fluid. The flushing fluid may comprise a liquid, the liquid may comprise water, or oil, or any liquid used to facilitate the drill operation. For example, the liquid may be any known liquid which may be used as a flushing fluid / and or an insulator for a drill operation.

[0045] The reservoir 50 may be located at the drill rig 2 or may be an external source. In the case of an external source the fluid reservoir 50 may be used to supply multiple drill rigs 2. The reservoir 50 may comprise a tank, or alternatively any natural or man-made body for containment of a fluid. The fluid transfer arrangement 26 is arranged such that the first fluid channel 28 is supplied by the reservoir 50 and the second fluid channel 30 supplies the reservoir 50 with the fluid, such that the fluid may be circulated between the reservoir 50 and the mineral substrate 6 in an anti-clockwise fashion. Alternatively, the fluid transfer arrangement 26 is arranged such that the second fluid channel 30 is supplied by the reservoir 50 and the first fluid channel 28 supplies the reservoir with the fluid, such that the fluid may be circulated between the reservoir 50 and the mineral substrate 10 in a clockwise fashion. Alternatively, both the first fluid channel 28 and the second fluid channel 30 can be arranged such that they may supply and be supplied with fluid to / from the reservoir 50. Alternatively, the second fluid channel 30 may be connected to a different reservoir or may simply release the liquid to be drained at a location distanced from the mineral substrate 10. The reservoir 50 may comprise separation means, such as filters, shale shakers, centrifuges, or cyclone separators, or the like, or combinations thereof, for removing rock fragments from the liquid. The reservoir 50 may contain a plurality of separation stages, such that rock fragments comprising different materials, grain sizes, or the like may be removed, for example having a coarse grain separation stage followed by a fine grain separation stage.

[0046] In the shown example, the fluid transfer arrangement 26 comprises a first pump 32 configured to pump the fluid through the first fluid channel 28. In the shown embodiment the first pump 32 is located on the first fluid channel 28. In alternative embodiments the first pump 32 may be located outside of the first fluid channel 28, for example at the reservoir 50, or at the volume containing the drill head 8. The drilling apparatus 4 further comprises an actuation arrangement 46 configured to move the sealing arrangement 12 along the central axis X of the drill string 6 towards the mineral substrate 10. The actuation arrangement 46 may comprise pneumatic, hydraulic, or electric means. In the shown embodiment the actuation arrangement 46 comprises two actuation mechanisms, a first actuation mechanism 62 acting between the first covering body 16 and a fixed beam 60, which may comprise part of the drill rig 2, and a second actuation mechanism 64 acting between the drill string 6 and the fixed beam 60.

[0047] Alternatively, the first covering body 16 and the drill string 6 may be connected to different fixed beams, or other fixed surfaces of the drill rig 2, or external to the drill rig 2, for example the ground. The first actuation mechanism 62 and the second actuation mechanism 64 may be operated individually or simultaneously. Further details regarding the control of the actuation arrangement will be discussed later in detail. Additionally, the first covering body 16 and / or the drill string 6 may be movably attached, or fixed, to a feed beam which may comprise part of the drill rig 2, said feed beam configured to move in a direction parallel to the central axis X of the drill string 6. Where one of the first covering body 16 or the drill string 6 are movably connected to a feed beam, the other component may be fixed to the feed beam. In one embodiment the actuation arrangement 46 may comprise an actuation mechanism whereby the first covering body 16 may be clamped to the drill string 6, and the drill string 6 is movable in a direction along its central axis X.

[0048] Alternatively, the actuation arrangement 46 may comprise an actuation mechanism acting between the first covering body 16 and the drill string 6 such that the first covering body 16 may be moved along the central axis X of the drill string 6. Any combination of the above-described connections is possible as long as relative movement between the first covering body 16 and the drill string 6 in the direction along the central axis X of the drill string 6 may be achieved.

[0049] The drilling apparatus 4 according to the illustrated embodiments further comprises a pulsed power generator 66 for generating high voltage current pulses for supplying the two electrodes 54 at the drill head 8. The drill rig 2 further comprises an electrical power supply 56 for powering the pulsed power generator 66. In alternative embodiments the drill head 8 may comprise rotary, top-hammer, or down-the-hole drilling means, or any known drilling means, which may be electrically, hydraulically or pneumatically powered, in which case the supply may comprise an electric, hydraulic or pneumatic source, such that the drill head 8 can be appropriately supplied such that it can break the mineral substrate 10. The pulsed power generator 66 comprises a pulse transformer 68 in the form of a bank of capacitors, connected to a power supply 56 via a charger 70. The electrodes 54 are selected and connected using switches (not shown). Using the switches, a short high voltage pulse is generated. The pulse is transferred to the electrodes 54. The pulsed power generator 66 is configured for generating pulses used for breaking the mineral substrate 10, such as nanosecond (ns) pulses that are passed to the electrodes 54.

[0050] The drilling apparatus 4 may further comprise an electronic control unit (not shown). The electronic control unit may be configured to control operation of the drilling apparatus 4 in response to signals received from an external control unit, such as a control unit of a machine in which the drilling apparatus 4 is provided. The electronic control unit may include a microprocessor, a microcontroller, a programmable digital signal processor or another programmable device. Thus, the control unit comprises electronic circuits and connections (not shown) as well as processing circuitry (not shown) for communicating with different parts of the drilling equipment 4 as well as with the external control unit. For example, the control unit may be configured for communicating with various sensors, devices, systems, and control units of the drilling apparatus 4. The control unit may control the transfer of fluid through the first fluid channel 28 and the second fluid channel 30, as well as the actuation arrangement 46. The control unit may also control the charger 70 as well as the switches (not shown). Alternatively, several separate control units may be provided.

[0051] The electronic control unit may comprise modules in either hardware or software, or partially in hardware or software, and communicate using known transmission buses such a CAN-bus and / or wireless communication capabilities. The processing circuitry may be a general-purpose processor or a specific processor. The control unit may comprise a non- transitory memory for storing computer program code and data. Thus, the skilled person realizes that the electronic control unit may be embodied by many different constructions.

[0052] Figs. 3a-3c illustrate the first covering body 16 in more detail. The first covering body 16 is in the shown example formed as a stepped pipe defining a first cavity 18 therethrough, with a first opening 20 at a first end, and a second opening 72 at a second end, the covering body extending between the first opening 20 and the second opening 72. The covering body 16 comprises a first portion 74 extending from the first opening 20, and a second portion 76 extending from the second opening 72. The second portion 76 has an outer surface having a smaller diameter than that of the first portion 74, and the inner surface of the second portion 76 has a smaller diameter than that of the first portion 74, such that the first cavity 18 defined by the first covering body 16 has a non-constant diameter. The first covering body 16 may comprise simply a pipe section comprising only a single portion defining a first cavity therethrough having a constant diameter. Alternatively, the first covering body 16 may comprise a bellows shaped body. The first portion 74 and second portion 76 may have a substantially constant wall thickness. The first portion 74 and the second portion 76 may have the same wall thickness, or alternatively the first portion 74 and the second portion 76 may have different wall thicknesses. Alternatively, the first portion 74 and / or the second portion 76 may have a non-constant wall thickness, for example the wall thickness may vary linearly, or non- linearly, along the axial length of the first covering body 16. The first portion 74 and the second portion 76 extend in a substantially axial direction. In alternative embodiments one or both of the portions may be tapered. Additionally, only the inner surface or the outer surface of the top and or bottom portions may be tapered. A lip portion extending in the radial direction may be formed at one or both of the ends of the first covering body 16, the lip portion extending in a radially inner direction, a radially outer direction, or a combination thereof. Whilst the illustrated embodiment is shown to be formed of a first portion 74 and a second portion 76, the first covering body 16 may be formed of any number of portions, for example the aforementioned single portion embodiment. In one embodiment the covering body may comprise a substantially disc-shaped body.

[0053] Alternatively, the first covering body 16 may comprise a substantially cup-shaped body, as long as the covering body may be configured such that it may form a volume delimited by at least the first covering body 16 and the mineral substrate 10.

[0054] The first covering body 16 may comprise a metal, such as steel, or may comprise a polymer, such as a rubber, or a composite material, or a combination thereof. The first covering body 16 may be formed as one piece, for example by an extrusion or a molding process, or may be formed of multiple pieces which may be joined by welding, adhesive, or any other known joining method.

[0055] Additionally, structural ribs (not shown) may be formed on the inner and or outer surface of the first covering body 16 such that the stiffness of the body may be improved. The structural ribs may extend in an axial direction, a circumferential direction, or any direction in between, or any combination thereof. Structural ribs may be formed from the same material as the top portion and / or bottom portion and may be formed integrally therewith. Alternatively, structural ribs may be formed of a different material.

[0056] The first covering body 16 comprises a first axial sealing element 22 associated with the first opening 20 and configured to seal the first cavity 18 towards the mineral substrate 10 when the sealing arrangement 12 is positioned such that it forms a first volume 24 located at least partly inside the first cavity 18 and delimited by at least the first covering body 16 and the mineral substrate 10. The first axial sealing element 22 may be integrally formed with the first covering body 16, or alternatively the first axial sealing element 22 may comprise a separate component. If the first axial sealing element 22 comprises a separate component, said separate component may comprise a different material, for example it may be advantageous to use steel for the first covering body 16 and rubber for the first axial sealing element 22. Additionally, the first axial sealing element 22 may be joined to the first covering body 16 using any known method. Alternatively, the first axial sealing element 22 may remain detached from the first covering body 16. The first covering body 16 and / or the first axial sealing element 22 may be adapted such that they may be fitted together, for example by way of cut-outs, grooves or the like. In the shown embodiment the first axial sealing element 22 comprises a ring-shaped element having a wall thickness approximately equal to that of the first covering body 16. In alternative embodiments the first axial sealing element 22 may have a larger, or smaller wall thickness. In the shown embodiment the first axial sealing element 22 comprises a square toroid, alternatively the toroid may be formed of a rectangle, circle, triangle, or any shape. It may be advantageous for the first axial sealing element 22 to have any number of protrusions extending axially, such that they may extend towards the mineral substrate 10. Where a number of protrusions are formed the protrusions may be arranged circumferentially and / or radially along the first axial sealing element 22. A protrusion may be formed having a number of radially extending slits, cut-outs, or the like, formed in any shape and / or orientation.

[0057] As shown in Fig. 3c, a hole 48 may be formed in the first covering body 16 such that the second fluid channel 30 is in fluid communication with the first volume 24 via the hole 48 formed in the first covering body 16. The hole 48 comprises an axially extending channel extending through the second portion 76 of the first covering body 16. Additionally, the hole 48 may comprise a channel extending in a direction at an inclination to the axial direction. Alternatively, the hole 48 may be formed by a radially extending channel extending through the first covering body 16. Additionally, the hole 48 may comprise a channel extending in a direction at an inclination to the radial direction. The hole may be configured such that the second fluid channel 30 ends at the hole 48. Alternatively, the hole 48 may be configured such that the second fluid channel 30 extends all the way through the hole 48, extending into the first volume. Alternatively, the second fluid channel 30 may extend through the hole 48 such that its end surface lies flush with the end surface of the first covering body 16. Alternatively, the second fluid channel 30 may extend part of the way into the hole 48. Where the second fluid channel 30 extends part of the way into the hole 48, the hole 48 may feature adaptations for positioning the second fluid channel 30, for example, cut-outs, grooves or the like. In the shown embodiment the hole 48 has a constant diameter. In alternative embodiments the diameter of the hole may vary, for example the diameter of the hole may vary linearly, or non-linearly, along the length of the formed channel. The hole 48 may feature ribs or a helical thread, or the like for interfacing with the second fluid channel 30. The second fluid channel 30 may additionally feature ribs or a helical thread, or the like for interfacing with the hole 48. The second fluid channel 30 may be joined to the first covering body 16 by any known method, for example welding, adhesive, or the like.

[0058] At least one sealing element (not shown) may form a sealing between the second fluid channel 30 and the hole 48. The sealing element may be integrally formed with the first covering body 16, or alternatively the sealing element may comprise a separate component. If the sealing element comprises a separate component, said separate component may comprise a different material, for example it may be advantageous to use steel for the first covering body and rubber for the sealing element. Additionally, the sealing element may be joined to the first covering body 16 using any known method. Alternatively, the sealing element may remain detached from the first covering body 16. The first covering body 16 and / or the sealing element may be adapted such that they may be fitted together, for example by way of cut-outs, grooves or the like. The sealing element may comprise a ring-shaped element formed or located anywhere along the length of the hole 48 of the first covering body 16. Additionally, it may be possible to use multiple sealing elements. The sealing element may comprise a flat disc shape, or toroid formed of a rectangle, circle, triangle, or any shape. It may be advantageous for the sealing element to have any number of protrusions extending radially relative to the hole 48. Where a number of protrusions are formed the protrusions may be arranged axially and / or circumferentially along the sealing element, relative to the hole 48. A protrusion may be formed having a number of radially extending slits, cut-outs, or the like, formed in any shape and / or orientation. Additionally, it may be possible to form a hole at least partially through the radial sealing element 14 or the axial sealing element 22, whereby the radial sealing element 14 or the axial sealing element 22 may be further adapted to seal between the hole 48 and the second fluid channel 30.

[0059] Fig. 4 illustrates schematically a drilling apparatus 4 according to an embodiment of the disclosure. The drilling apparatus of Fig. 4 differs from that of Fig. 2 as the fluid transfer arrangement 26 further comprises a second pump 34 configured to pump the fluid through the second fluid channel 30. In the shown embodiment the second pump 34 is located on the second fluid channel 30. In alternative embodiments the second pump 34 may be located outside of the second fluid channel 30, for example at the reservoir 50, or at the first volume 24.

[0060] Fig. 5 illustrates schematically a drilling apparatus 4 according to an embodiment of the disclosure. The embodiment differs from that of Fig. 2 as the sealing arrangement 12 comprises a second covering body 36 formed around the central axis X of the drill string 6 and defining a second cavity 38 (see Figs. 6b-6c) therethrough, with a second opening 40 (see Figs. 6b-6c) at an end portion of the second covering body 36 for the drill head 8. The second covering body 36 comprises a second axial sealing element 42, associated with the second opening 40 and configured to seal the second cavity 38 towards the mineral substrate 10 when the sealing arrangement 12 is positioned such that it forms a second volume 44 surrounded by the first volume 24 and delimited by the second covering body 36 and the mineral substrate 10. The second covering body 36 will be described in more detail with reference to Fig. 6a-6c.

[0061] In the shown embodiment the radial sealing element 14, configured to seal between the sealing arrangement 12 and the drill string 6, is associated with the second covering body 36. The radial sealing element is configured to seal the second covering body 36 towards the drill string 6. The radial sealing element 14 may be integrally formed with second covering body 36, or alternatively the radial sealing element 14 may comprise a separate component. If the radial sealing element 14 comprises a separate component, said separate component may comprise a different material, for example it may be advantageous to use steel for the second covering body 36 and rubber for the radial sealing element 14. Additionally, the radial sealing element 14 may be joined to the second covering body 36 body using any known method. Alternatively, the radial sealing element 14 may remain detached from the second covering body 36. The second covering body 36 and / or the radial sealing element 14 may be adapted such that they may be fitted together, for example by way of cut-outs, grooves or the like. In the shown embodiment the radial sealing element 14 comprises a ring-shaped element formed in the innermost top corner of the second covering body 36. In alternative embodiments the radial sealing element 14 may be located anywhere along the length of the second covering body. In one embodiment the radial sealing element 14 may be located at the top facing surface of the second covering body. Additionally, it may be possible to use multiple radial sealing elements to seal the second covering body 36 to the drill string. In the shown embodiment the radial sealing element 14 comprises a square toroid, alternatively the toroid may be formed of a rectangle, circle, triangle, or any shape. It may be advantageous for the radial sealing element 14 to have any number of protrusions extending radially towards the drill string 6. Where a number of protrusions are formed the protrusions may be arranged axially and / or circumferentially along the radial sealing element. A protrusion may be formed having a number of radially extending slits, cut-outs, or the like, formed in any shape and / or orientation.

[0062] The first covering body 16 is arranged on the outside of the second covering body 36. The first covering body 16 may be movable relative to the second covering body 36. Alternatively, the first covering body 16 may be fixed to the second covering body 36, using any known fixation method, such as welding, adhesive, etc. Alternatively, it may be possible that the first covering body 16 and the second covering body 36 are integrally formed. At least one sealing element (not shown) may seal between the first covering body 16 and the second covering body 36. The sealing element may comprise a radial sealing element and / or an axial sealing element. The sealing element may be fixed to the first covering body 16 and / or the second covering body 36 using any known fixing method.

[0063] Alternatively, the first covering body 16 and the second covering body 36 may be configured such that they do not contact each other. When configured such that the first covering body 16 and the second covering body 36 do not contact each other both the first covering body 16 and the second covering body 36 may have at least one radial sealing element associated therewith configured to seal between the sealing arrangement 12 and the drill string 6.

[0064] Additionally, the sealing arrangement 12 may comprise more than two covering bodies (not shown). For example, at least one additional covering body may be arranged between the first covering body 16 and the second covering body 36. It may also be possible for at least one additional covering body to be arranged around the first covering body 16.

[0065] The drilling apparatus 4 may as shown in Fig. 5 further comprise an actuation arrangement 46 configured to move the sealing arrangement 12 along the central axis X of the drill string 6 towards the mineral substrate. The actuation arrangement 46 may comprise pneumatic, hydraulic, or electric means. In the shown embodiment the actuation arrangement 46 comprises three actuation mechanisms, a first actuation mechanism 62 acting between the first covering body 16 and a fixed beam 60, which may comprise part of the drill rig 2, a second actuation mechanism 64 acting between the drill string 6 and the fixed beam 60, and a third actuation mechanism 78 acting between the second covering body 36 and the fixed beam 60. Alternatively, the first covering body 16, the second covering body 36 and the drill string 6 may be connected to different fixed beams, or other fixed surfaces of the drill rig 2, or external to the drill rig 2, for example the ground. The first actuation mechanism 62, the second actuation mechanism 64, and the third actuation mechanism 78 may be operated individually or simultaneously. Further details regarding the control of the actuation arrangement will be discussed later in detail. Additionally, the first covering body 16, the second covering body 36, and / or the drill string 6 may be attached to a feed beam which may comprise part of the drill rig 2, said feed beam configured to move in a direction parallel to the central axis X of the drill string 6. Where at least one of the first covering body 16, the second covering body 36, and / or the drill string 6 are movably connected to a feed beam, one of the first covering body 16, the second covering body 36, and / or the drill string 6 may be fixed to the feed beam. In one embodiment the actuation arrangement 46 may comprise an actuation mechanism whereby the first covering body 16 and / or the second covering body 36 may be clamped to the drill string 6, and the drill string 6 is movable in a direction along its central axis X. Alternatively, the actuation arrangement 46 may comprise an actuation mechanism acting between the first covering body 16 and / or second covering body 36 and the drill string 6 such that the first covering body 16 and / or second covering body 36 may be moved along the central axis X of the drill string 6. The first covering body 16 and the second covering body 36 may be connected to each other. Any combination of the above-described connections is possible as long as relative movement between the sealing arrangement 12 and the drill string 6 in the direction along the central axis X of the drill string 6 may be achieved.

[0066] Fig. 6a-6c illustrate the second covering body 36 in more detail. The second covering body 36 is formed as a stepped pipe defining a second cavity 38 therethrough, with a first opening 40 at a first end, and a second opening 82 at a second end, the covering body extending between the first opening 40 and the second opening 82. The second covering body 36 comprises a first portion 84 extending from the first opening 40, and a second portion 86 extending from the second opening 82. The second portion 86 has an outer surface having a smaller diameter than that of the first portion 84, and the inner surface of the second portion 86 has a smaller diameter than that of the first portion 84, such that the second cavity 38 defined by the second covering body 36 has a non-constant diameter. The second covering body 36 may comprise a pipe section comprising only a single portion defining a first cavity therethrough having a constant diameter. Alternatively, the second covering body 36 may comprise a bellows shaped body. The first portion 84 and second portion 86 may have a substantially constant wall thickness. The first portion 84 and the second portion 86 may have the same wall thickness, or alternatively the first portion 84 and the second portion 86 may have different wall thicknesses. Alternatively, the first portion 84 and / or the second portion 86 may have a non-constant wall thickness, for example the wall thickness may vary linearly, or non-linearly, along the axial length of the second covering body 36. The first portion 84 and the second portion 86 extend in a substantially axial direction. In alternative embodiments one or both of the portions may be tapered. Additionally, only the inner surface or the outer surface of the top and or bottom portions may be tapered. A lip portion extending in the radial direction may be formed at one or both of the ends of the second covering body 36, the lip portion extending in a radially inner direction, a radially outer direction, or a combination thereof. Whilst the illustrated embodiment is shown to be formed of a first portion 84 and a second portion 86, the second covering body 36 may be formed of any number of portions, for example the aforementioned single portion embodiment. In one embodiment the covering body may comprise a substantially disc-shaped body. Alternatively, the second covering body 36 may comprise a substantially cup-shaped body, as long as the covering body may be configured such that it may form a second volume 44 surrounded by the first volume 24, formed by the first covering body 16, and delimited by said second covering body 36 and said mineral substrate 10. In the shown embodiment of Fig. 5, the second covering body 36 is longer than the first covering body 16 in the axial direction. In alternative embodiments the second covering body 36 may be shorter than the first covering body 16.

[0067] The second covering body 36 may comprise a metal, such as steel, or may comprise a polymer, such as a rubber, or a composite material, or a combination thereof. The second covering body 36 may comprise the same material as the first covering body 16, or it may comprise a different material, for example the first covering body 16 may comprise steel and the second covering body 36 may comprise rubber in the form of a bellows. The second covering body 36 may be formed as one piece, for example by an extrusion or a molding process, or may be formed of multiple pieces which may be joined by welding, or any other known joining method.

[0068] Additionally, structural ribs (not shown) may be formed on the inner and / or outer surface of the second covering body 36 such that the stiffness of the body may be improved. The structural ribs may extend in an axial direction, a circumferential direction, or any direction in between, or any combination thereof. Structural ribs may be formed from the same material as the top portion and / or bottom portion and may be formed integrally therewith. Alternatively, structural ribs may be formed of a different material.

[0069] The second covering body 36 comprises a second axial sealing element 42 associated with the first opening 40 of the second covering body 36 and configured to seal the second cavity 38 of the second covering body 36 towards the mineral substrate 10 such that it forms a second volume 44 when the sealing arrangement 12 is positioned such that it forms a first volume 24 located at least partly inside the first cavity 18 of the first covering body 16 and delimited by at least the first covering body 16 and the mineral substrate 10. The second axial sealing element 42 may be integrally formed with the second covering body 36, or alternatively the first axial sealing element may comprise a separate component. If the second axial sealing element 42 comprises a separate component, said separate component may comprise a different material, for example it may be advantageous to use steel for the second covering body 16 and rubber for the second axial sealing element 42. Additionally, the second axial sealing element 42 may be joined to the second covering body 36 using any known method. Alternatively, the second axial sealing element 42 may remain detached from the second covering body 36. The second covering body 36 and / or the second axial sealing element 42 may be adapted such that they may be fitted together, for example by way of cut-outs, grooves or the like. In the shown embodiment the second axial sealing element 42 comprises a ring-shaped element having a wall thickness approximately equal to that of the second covering body 36. In alternative embodiments the second axial sealing element 42 may have a larger, or smaller wall thickness. In the shown embodiment the second axial sealing element 42 comprises a square toroid, alternatively the toroid may be formed of a rectangle, circle, triangle, or any shape. It may be advantageous for the second axial sealing element 42 to have any number of protrusions extending axially, such that they may extend towards the mineral substrate 10. Where a number of protrusions are formed the protrusions may be arranged circumferentially and / or radially along the second axial sealing element 42. A protrusion may be formed having a number of radially extending slits, cut-outs, or the like, formed in any shape and / or orientation.

[0070] Fig. 7 illustrates schematically a sealing arrangement 12 according to an embodiment of the disclosure. The sealing arrangement 12 comprises a first covering body 16 and a second covering body 36. A spring element 45 is positioned between the first covering body 16 and the second covering body 36. The spring element 45 may comprise a compression spring, or any other type of spring, or any elastically deformable material. The spring element may comprise a single spring configured to surround the drill string 6, or alternatively multiple springs can be distributed around the drill string 6. The spring element 45 may be fixed to the first covering body 16 and / or the second covering body 36. The first covering body 16 and / or the second covering body 36 may have cutouts, grooves, and / or protrusions for engaging with the spring element 45. In the shown embodiment an actuation mechanism 80 is connected to the first covering body 16 such that the first covering body 16 is movably connected to a fixed beam 60. The first covering body 16 may be moved towards the mineral substrate 10, the second covering body 36 being moved therewith, until the second axial sealing element 42, which may be configured to extend past the first axial sealing element 22, comes into contact with the mineral substrate 10, and becomes sealingly engaged thereto. The first covering body 16 can then continue to be moved downwards, such that the spring element 45 is compressed, until the first axial sealing element 22 comes into contact with the mineral substrate 10 and becomes sealingly engaged thereto. In alternative embodiments the actuation mechanism 80 may be connected to the second covering body 36 and / or the first axial sealing element 22 may extend past the second axial sealing element 42.

[0071] A method for controlling a drilling apparatus 4 as described above is illustrated in Fig. 8. The method comprises the following steps, which, unless otherwise indicated, may be taken in any suitable order:

[0072] S1 : adjoining the sealing arrangement 12 with the mineral substrate 10 by moving the sealing arrangement 12 along the central axis X of the drill string 6 towards the mineral substrate 10.

[0073] S2: supplying a fluid to a volume containing the drill head 8 via the fluid transfer arrangement 26.

[0074] S3: controlling a pressure in a volume enclosed by the sealing arrangement by controlling a fluid flow through the fluid transfer arrangement 26.

[0075] The first step S1 may be manually controlled by an operator via an external control unit (as described with reference to Fig. 2). Alternatively, the first step S1 may be fully automated when the drill rig 2 is placed in position. Alternatively, the first step S1 may be at least partially automated. For example, the operator may control the start of the first step, to move the sealing arrangement 12 along the central axis X of the drill string 6 towards the mineral substrate 10, using the external control unit. The electronic control unit may subsequently control the movement of the sealing arrangement 12 such that it adjoins with the mineral substrate 10. The operator may define parameters, such as the composition of the mineral substrate 10 which the electronic control unit may use to control the drill operation. Alternatively, the electronic control unit may be preprogrammed with operating parameters. The drilling apparatus 4 may comprise external sensors which supply data to the electronic control unit 16 which can be used for control of the first step based on the defined parameters. For example, sensors may be used to determine the distance between the sealing arrangement 12 and the mineral substrate 10, for example, a laser, ultrasonic, or infrared sensor, or any known sensor which can be used to measure a distance. It is also possible to use sensors to determine that sealing has been achieved, for example by measuring contact using a resistive, capacitive, piezoelectric, optical, or micro electro-mechanical system sensor, or any known sensor which can be used to measure contact. The adjoining of the sealing arrangement 12 may be determined when contact between the sealing arrangement 12 and the mineral substrate 10 has been achieved. Alternatively, it may be determined that the adjoining of the sealing arrangement 12 and the mineral substrate 10 has been achieved after a movement has been performed subsequent to an initial contact between the sealing arrangement 12 and the mineral substrate 10. The movement performed subsequent to the initial contact may, for example, take into account the composition of the mineral substrate 10 at the surface. Additionally, it may be possible to perform an operation to test the sealing arrangement, for example by supplying a fluid, said fluid could be a fluid other than the fluid supplied in the second step, for example a fluid could be supplied to a volume enclosed by the sealing arrangement and a detection of a leakage may be monitored. It is possible that a number of the above-described methods are used to ensure that the adjoining of the sealing arrangement 12 and the mineral substrate has been achieved.

[0076] The adjoining of the sealing arrangement 12 and mineral substrate 10 may be performed only once, as initial step. Alternatively, the sealing arrangement 12 may be continuously moved towards the mineral substrate 10, such that it is pressed towards the mineral substrate 10. Alternatively, the sealing arrangement 12 may be intermittently moved towards the mineral substrate 10, whereby such movement instances may comprise preset intervals. Alternatively, the need for an additional movement instance may be determined by sensors, for example, the detection of a loss of contact exceeding a threshold time, or a leakage exceeding a threshold amount, or any other method for determining that the positioning of the sealing arrangement 12 relative to the mineral substrate 10 is providing an unacceptable level of sealing.

[0077] The first step may comprise movement of only the sealing arrangement 12, whereby the drill head 8 may already be positioned at the mineral substrate 10. Alternatively, the drill head 8 may be simultaneously with the sealing arrangement 12, either by being fixed thereto, or via simultaneous control of two separate actuation mechanisms. Alternatively, the drill head 8 may be positioned at the mineral substrate 10 after adjoining of the sealing arrangement 12 and the mineral substrate 10 has been achieved. It is also possible that a combination of the aforementioned movements can be made such that both adjoining of the sealing arrangement 12 and the mineral substrate 10 and positioning of the drill head 8 at the mineral substrate 10, such that a drilling operation may begin, is achieved. The second step S2 of supplying a fluid to a volume containing the drill head 8 via the fluid transfer arrangement 26 may begin automatically when the sealing arrangement 12 has been adjoined with the mineral substrate 10. Alternatively, the second step may begin when the sealing arrangement 12 has been at least partially adjoined with the mineral substrate 10, for example where the sealing arrangement 12 comprises at least a first covering body 16 and a second covering body 36 where at least one of the axial sealing elements of the covering bodies has been adjoined with the mineral substrate 10. Alternatively, the second step may begin before the first step, or at any time before the completion of the first step. For example, where a hole has already been formed in the mineral substrate 10, and the fluid to be supplied comprises a liquid, the liquid may be supplied via the fluid transfer arrangement 26 to the hole formed in the mineral substrate 10 before the sealing arrangement 12 has been adjoined with the mineral substrate 10. However, in such a case it is preferable that the sealing arrangement 12 is at least partially adjoined with the mineral substrate 10 before a liquid level exceeds the height of the hole, if a liquid level exceeding the height of the hole is to be achieved, it is possible to achieve the supply of the fluid to be performed incrementally. For example, a first increment will fill the hole, then in a second increment, after the sealing arrangement 12 is adjoined with the mineral substrate 10, the sealed volume may be supplied.

[0078] The second step of supplying a fluid to a volume containing the drill head 8 via the fluid transfer arrangement 26 may comprise a fluid flow in the first fluid channel 28 and / or the second fluid channel 30.

[0079] The third step S3 of controlling a pressure in a volume enclosed by the sealing arrangement 12 may begin after the second step has been completed. The end of the second step may be determined by a sensor. The sensor may comprise a pressure sensor. If the fluid comprises a liquid the sensor may comprise a liquid level sensor. If the fluid comprises a gas the sensor may comprise a gas concentration sensor concentration sensor. The end of the second step may also be determined when a known volume of the fluid has been supplied to the enclosed volume. The known volume may be equal to the volume enclosed by the sealing arrangement 12. Alternatively, if a hole has been formed prior to the first step, the volume of the hole may first need to be determined, for example by use of sensors. The third step of controlling a pressure in a volume enclosed by the sealing arrangement comprises controlling a fluid flow through the fluid transfer arrangement 12. The fluid can be controlled such that a flow is achieved in the first fluid channel 28 and / or the second fluid channel 30. The control of the flow can comprise controlling the rate of the flow in the first fluid channel 28 and / or the second fluid channel 30. The flow can be controlled by way of the first pump 32 (as detailed with reference to Fig. 2) and / or the second pump 34 (as detailed with reference to Fig. 4). It is also possible to control the flow by way of any know fluid transfer device or by use of valves (not shown) on the first fluid channel 28 and / or the second fluid channel 30. The flow in each of the first fluid channel 28 and / or the second fluid channel 30 may be directed towards a volume enclosed by the sealing arrangement 12, or away from the sealing arrangement 12.

[0080] The third step may comprise controlling the fluid transfer arrangement 26 such that a pressure in the first volume 24 higher than an atmospheric pressure is generated. Alternatively, the third step may comprise controlling the fluid transfer arrangement 26 such that a pressure in the first volume 24 lower than an atmospheric pressure is generated.

[0081] Where the sealing arrangement 12 comprises a first covering body 16 and a second covering body 36 (as detailed with reference to Fig. 5) the third step may comprise controlling the fluid transfer arrangement 26 such that a pressure in the second volume 44 is greater than a pressure in the first volume 24 is generated.

[0082] An additional step comprising a drilling operation whereby the drill head 8 breaks the mineral substrate 10 (as detailed with reference to Fig. 1) may be performed after a desired pressure has been obtained in the third step. Alternatively, it may be possible to begin a drilling operation during any of the steps provided. For example, a drilling operation may begin once a drill head is sufficiently surrounded by the fluid during the second step.

Claims

CLAIMS1. A drilling apparatus (4), said drilling apparatus (4) comprising:- a drill string (6), extending along a central axis (X),- a drill head (8), located at an end of said drill string (6) and configured to break a mineral substrate (10),- a sealing arrangement (12) formed around the central axis (X) of said drill string (6), wherein said sealing arrangement (12) and said drill string (6) are movable relative to one another, said movement being directed along the central axis (X) of said drill string (6), said sealing arrangement (12) comprising:- a radial sealing element (14), configured to seal between said sealing arrangement (12) and said drill string (6),- a first covering body (16), formed around the central axis (X) of said drill string (6), and defining a first cavity (18) therethrough, with a first opening (20) at an end portion of said first covering body (16) for said drill head (8), said first covering body (16) comprising:- a first axial sealing element (22) associated with said first opening (20) and configured to seal said first cavity (18) towards said mineral substrate (10) when said sealing arrangement (12) is positioned such that it forms a first volume (24) located at least partly inside said first cavity (18) and delimited by at least said first covering body (16) and said mineral substrate (10), wherein said drilling apparatus (4) comprises a fluid transfer arrangement (26), said fluid transfer arrangement (26) comprising a first fluid channel (28) in fluid communication with a volume containing said drill head (8) when said sealing arrangement (12) forms said first volume (24), and a second fluid channel (30) in fluid communication with said first volume (24).

2. The drilling apparatus (4) according to claim 1, wherein said fluid comprises a flushing fluid, wherein said flushing fluid comprises a liquid.

3. The drilling apparatus (4) according to any one of the preceding claims, wherein said fluid transfer arrangement (26) comprises a first pump (32) configured to pump said fluid through said first fluid channel (28).

4. The drilling apparatus (4) according to any one of the preceding claims, wherein said fluid transfer arrangement (26) comprises a second pump (34) configured to pump said fluid through said second fluid channel (30).

5. The drilling apparatus (4) according to any one of the preceding claims, wherein said fluid transfer arrangement (26) is configured to generate a pressure in said first volume (24) higher than an atmospheric pressure.

6. The drilling apparatus (4) according to any one of claims 1-4, wherein said fluid transfer arrangement (26) is configured to generate a pressure in said first volume (24) lower than an atmospheric pressure.

7. The drilling apparatus (4) according to any one of the preceding claims, wherein said sealing arrangement (12) comprises a second covering body (36) formed around the central axis (X) of said drill string (6), and defining a second cavity (38) therethrough, with a second opening (40) at an end portion of said second covering body (36) for said drill head (8), said second covering body (36) comprising:- a second axial sealing element (42), associated with said second opening (40) and configured to seal said second cavity (38) towards said mineral substrate (10) when said sealing arrangement (12) is positioned such that it forms a second volume (44) surrounded by said first volume (24) and delimited by said second covering body (36) and said mineral substrate (10).

8. The drilling apparatus (4) according to claim 7, wherein said fluid transfer arrangement (26) is configured to generate a pressure in said second volume (44) greater than a pressure in said first volume (24).

9. The drilling apparatus (4) according to any one of claims 7-8, wherein said sealing arrangement (26) comprises at least one spring element (45) extending between the first covering body (16) and said second covering body (36) and configured to bias said second covering body (36) towards said mineral substrate (10).

10. The drilling apparatus (4) according to any one of the preceding claims, wherein said drilling apparatus (4) comprises an actuation arrangement (46) configured to move said sealing arrangement (12) along the central axis (X) of said drill string (6) towards said mineral substrate (10).

11. The drilling apparatus (4) according to any one of the preceding claims, wherein said second fluid channel (30) is in fluid communication with said first volume (24) via a hole (48) formed in said first covering body (16).

12. The drilling apparatus (4) according to any one of the preceding claims, wherein said first fluid channel (28) and said second fluid channel (30) are in fluid communication with a reservoir (50) and said fluid transfer arrangement (26) isconfigured to circulate fluid between a volume enclosed by said first volume (24) and said reservoir (50).

13. A drill rig (2) comprising the drilling apparatus (4) according to any one of the preceding claims.

14. A method of controlling the drilling apparatus (4) according to any one of claims 1-12, said method comprising:- adjoining said sealing arrangement (12) with said mineral substrate (10) by moving said sealing arrangement (12) along the central axis (X) of said drill string (6) towards said mineral substrate (10),- supplying a fluid to a volume containing said drill head (8) via said fluid transfer arrangement (26)- controlling a pressure in a volume enclosed by said sealing arrangement (12) by controlling a fluid flow through said fluid transfer arrangement (26).

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