AU2021105653A4

AU2021105653A4 - Multi-Purpose Orientation Measurement System

Info

Publication number: AU2021105653A4
Application number: AU2021105653A
Authority: AU
Inventors: Nicky KLEYN; Nicolas KLEYN
Original assignee: Borecam Asia Pte Ltd
Current assignee: Borecam Asia Pte Ltd
Priority date: 2019-01-13
Filing date: 2021-08-17
Publication date: 2021-10-14
Anticipated expiration: 2028-01-13
Also published as: AU2020200242B2; AU2020200242A1

Abstract

A multi-purpose orientation measurement system (10) comprising a surface communications device (20) and a downhole unit (62). The downhole unit (62) has a first measuring subsystem (12) for measuring borehole orientation and a second measuring subsystem (14) for measuring core orientation. The downhole unit (62) is adapted to fixedly engage an inner tube (1). In use, when the downhole unit (62) detects that the inner tube (1) has been received within a core barrel (7), the downhole unit (1) stores measurements taken by the first measuring subsystem (12) relating orientation of the borehole. Thereafter, the downhole unit (62) operates to store measurements taken by the second measuring subsystem (14) indicative of the orientation of the fixedly attached inner tube (1). The downhole unit (62) is further operable to communicate the stored measurements to the surface communications device (20) on return of the downhole unit (62) to the surface. Figure 2 .Zfz ~Lf~ - 1% 20c 42.. 9 S

Description

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"MULTI-PURPOSE ORIENTATION MEASUREMENT SYSTEM" FIELD OF THE INVENTION

[0001] The invention relates to a multi-purpose orientation measurement system. The invention is particularly suited to capturing both borehole orientation and core orientation measurements in a single drilling run.

BACKGROUND TO THE INVENTION

[0002] The following discussion of the background to the invention is intended to facilitate an understanding of the present invention. However, it should be appreciated that the discussion is not an acknowledgment or admission that any of the material referred to was published, known or part of the common general knowledge in any jurisdiction as at the priority date of the application.

[0003] In mining operations, the drilling of a hole is performed with the assistance of multiple pipe segments. Each pipe segment is typically 3m or 6m in length. Thus a 100m plus drill hole typically comprises around 20 pipe segments.

[0004] Being made up of multiple pipe segments, it is not expected that the drill hole will be perfectly linear. In fact, in some instances, the ability of each pipe segment to be moved out of linear orientation relative to its adjacent pipe segments can be exploited to direct the drill hole to a desired location.

[0005] At the same time, the purpose of drilling the hole is to obtain one or more samples of the material being drilled. These drill samples can then provide geologists with information as to whether any minerals exist at the drilled location and/or whether the minerals exist in a quantity which makes mining commercially viable.

[0006] While the geologist can easily determine what minerals may exist in the drilled location from the sample taken, the question of whether the mineral exists in a commercially viable quantity is generally one that has to be determined through proving an ore body. Proving an ore body generally requires information not only of the drill hole itself, but also of the core samples taken from each drill hole.

[0007] To elaborate, measurements as to the orientation of the drill hole show the geophysical position of the point where the core sample is taken, but not the orientation of the core sample itself. Thus, a separate orientation measurement is generally taken of the core sample. The combination of the two measurements commonly referred to as borehole orientation and core orientation respectively - can then give the geologist and other mining professionals a better indication of the shape, size and position of the ore body.

[0008] However, unlike borehole orientation measurements which are typically reliable - or at least can be re-performed without issue, the driller must obtain an accurate core orientation measurement prior to extracting the core sample. It is therefore imperative that core orientation measurements be as accurate as possible to ensure that the core samples obtained provide as accurate a picture as possible of the ore body to the geologist or other mining professionals.

[0009] In more recent years, attempts have been made to obtain borehole orientation and core orientation measurements in a single drilling run. A prime example is the concept disclosed in AU 2017210756 titled "Method and system for enabling acquisition of borehole survey data and core orientation data."

[0010] The problem with this concept is that it is overly complex with two differing parts operating in conjunction downhole to determine the required orientation measurements. This added complexity poses a greater risk that one or more components will fail resulting in the user being unable to obtain the data they require, either in whole or in part.

[0011] It is therefore an object of the present invention to provide a further alternative multi-purpose orientation measurement system.

SUMMARY OF THE INVENTION

[0012] Throughout this document, unless otherwise indicated to the contrary, the terms "comprising", "consisting of', and the like, are to be construed as non exhaustive, or in other words, as meaning "including, but not limited to".

[0013] In accordance with a first aspect of the present invention there is a multi purpose orientation measurement system comprising:

a surface communications device; and

a downhole unit, the downhole unit having a first measuring subsystem for measuring borehole orientation and a second measuring subsystem for measuring core orientation, where the downhole unit is adapted to fixedly engage an inner tube and where, in use, when the downhole unit detects that the inner tube has been received within a core barrel, the downhole unit stores measurements taken by the first measuring subsystem relating orientation of the borehole and thereafter, store measurements taken by the second measuring subsystem indicative of the orientation of the fixedly attached inner tube, the downhole unit then operable to communicate the stored measurements to the surface communications device on return of the downhole unit to the surface.

[0014] Preferably, the first measuring subsystem comprises a gyroscope and triaxial accelerometers for determining azimuth and dip measurements.

[0015] Preferably, the downhole unit has processing means for detecting a trigger event, the processing means operable to shutdown the second measuring system on detection of the trigger event.

[0016] In accordance with a second aspect of the present invention there is a method of obtaining orientation measurements during drilling comprising the steps of:

attaching an inner tube to a downhole unit such that the downhole unit and inner tube are in fixed rotational alignment;

positioning the downhole unit such that the attached inner tube is received within a core barrel;

on detecting that the inner tube is received within the core barrel:

storing measurements taken by a first measuring subsystem indicative of the orientation of the borehole; and

thereafter storing measurements taken by a second measuring subsystem indicative of the orientation of the inner tube;

on return of the downhole unit to the surface, communicating the stored measurements to a surface communications device.

[0017] Preferably, the method further includes the step of setting operational parameters for the drilling run by way of the surface communications device, the surface communications device thereafter operable to communicate the operational parameters to the downhole unit.

[0018] Preferably, the method further includes the step of waiting a predetermined period of time between storing measurements taken by the first measuring subsystem and storing measurements taken by the second measuring subsystem.

[0019] Preferably, the method further includes the step of waiting a predetermined period of time between detecting that the inner tube is received within the core barrel and the step of storing measurements taken by the first measuring subsystem.

[0020] Preferably, the method includes the step of shutting down the first measuring subsystem after storing measurements obtained therefrom.

[0021] Preferably, the method further includes the steps of detecting a trigger event and, on detection of the trigger event, shutting down the second measuring subsystem.

[0022] Preferably the measurements taken by the first measuring subsystem include measurements from which azimuth and dip can be calculated.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a schematic representation of prior art drill strings and drill bits.

Figure 2 is a schematic representation of a first embodiment of the present invention.

Figure 3 is a schematic representation of a downhole unit as used in a second embodiment of the present invention.

PREFERRED EMBODIMENTS OF THE INVENTION

[0024] Specific embodiments of the present invention are now described in detail. The terminology used herein is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the present invention.

[0025] In accordance with a first embodiment of the invention there is a multi purpose orientation system 10. The multi-purpose orientation system 10 comprises:

• a first measuring subsystem 12 for measuring the orientation of a borehole; • a second measuring subsystem 14 for measuring the orientation of a connected inner tube 1; • a control and storage subsystem 16; • a housing 18; • a handset 20.

[0026] The first measuring subsystem 12 comprises a vibrating structure gyroscope incorporating microelectromechanical systems technology 22 (more commonly referred to as a "MEMS gyroscope", a term which will be used throughout the remainder of this specification) and tri-axial accelerometers 24.

[0027] The second measuring subsystem 14 comprises the tri-axial accelerometers 24 and a temperature sensor 26.

[0028] The control and storage subsystem 16 is in data and control communication with the first measuring subsystem 12 and the second measuring subsystem 14. The control and storage subsystem 16 comprises:

• processing means 28; • storage means 30; • communication means 32; and • power means 34.

[0029] The processing means 28 is in data communication with the storage means 30 and in data and control communication with the communication means 32. The processing means 28, storage means 30 and communication means 32 are all powered by the power means 34.

[0030] The processing means 28 incorporates a real-time clock 36 and transitional memory 38.

[0031] The storage means 30, in this embodiment, takes the form of a solid state storage device. The storage means 30 is in fixed position.

[0032] The communication means 32 takes the form of a wireless communications unit 40 operating under the Bluetooth TM communications protocol. The wireless communications unit 40 is a two-way communications system, allowing it to both transmit and receive Bluetooth TMsignals.

[0033] The power means 34 takes the form of a rechargeable battery. The power means 34 is able to be recharged using induction charging techniques as are readily known and can easily be ascertained by the person skilled in the art.

[0034] The first measuring subsystem 12, second measuring subsystem 14 and control and storage subsystem 16 are all contained within housing 18. In this embodiment, cushioning (not shown) is provided in the housing to ensure that the first measuring subsystem 12, second measuring subsystem 14 and control and storage subsystem 16 are not subjected to excessive force during drilling.

[0035] The housing 18 is cylindrical in shape and has a first end 42 and a second end 44. First end 42 is adapted to allow the housing to be attached to a wireline (not shown) and floated down the interior of a drill string 2. Second end 44 is adapted to facilitate connection of the inner tube 1 by way of a screw thread.

[0036] To compensate for the extra length required to facilitate inclusion of the housing 18, an extension tube (not shown) is attached to the drill string 2.

[0037] The handset 20 comprises interface means 46, handset processing means 48, handset storage means 50, handset communication means 52 and handset power means 54.

[0038] Interface means 46 comprises a display unit 56 and a keypad 58.

[0039] Handset processing means 48 is in data communication with the handset storage means and in data and control communication with the interface means 46 and handset communication means 52. The interface means 46, the handset processing means 48, handset storage means 50 and handset communication means 52 are all powered by the power means handset 54.

[0040] The handset processing means 48 incorporates a real-time clock 64 and transitional memory 66.

[0041] The handset storage means 50, in this embodiment, again takes the form of a solid-state storage device. The storage means 30 is removable form the housing 68 which contains the interface means 46, handset processing means 48, handset storage means 50, handset communication means 52 and handset power means 54.

[0042] The handset communication means 52 takes the form of a wireless communications unit 60 operating under the Bluetooth TM communications protocol.

The wireless communications unit 60 is a two-way communications system, allowing it to both transmit and receive Bluetooth TMsignals.

[0043] The handset power means 54 takes the form of a rechargeable battery. In this embodiment, the handset power means 54 is able to be recharged through mating power connectors (not shown) provided in the handset 20 and an associated docking cradle (not shown).

[0044] Before referencing how this embodiment of the invention works in practice, it is necessary to understand the nature of the drill bit 3 attached to the drill string 2. This is shown in Figure 1.

[0045] The drill bit 3 has a cutting edge 4 disposed about its periphery 5. The drill bit 3 also has a threaded adaptor 6 positioned centrally to the periphery. The threaded adaptor 6 is used to threadedly engage a threaded portion (not shown) of a core barrel 7. In this manner, the core barrel 7 is screwed to the drill bit 3.

[0046] The core barrel 7 takes the form of a hollow cylinder that is axially aligned with the drill bit 3. The diameter of the core barrel 7 is slightly larger than that of the inner tube 1 so as to allow the inner tube 1 to be received therein.

[0047] This first embodiment of the invention will now be described in the context of its intended use.

[0048] A driller (not shown) screws the inner tube to second end 44 such that their respective threaded portions (not shown) mate. The driller then moves to the first end 42 and attached a wireline thereto.

[0049] With the housing 18 now ready for insertion into the drill string 2, the driller now initiates configuration of the multi-purpose orientation system 10. To do so, the driller retrieves the handset 20 and, using the interface means 46, operates to set the operational parameters for this drill run. It should be appreciated by the person skilled in the art that the operational parameters are varied and not necessarily relevant to the invention as described herein. However, examples of specific operational parameters are provided in more detail below.

[0050] Once the operational parameters for the drilling run have been set, the driller initiates operation of the multi-purpose orientation system 10. This commences with the handset communication means 52 establishing a communications channel with communication means 32. Following establishment of this communications channel, the handset processing means 48 operates to send the operational parameters entered by the driller, as relevant to processing means 28, to the processing means 28 for storage and reference in transitional memory 38.

[0051] At the same time, the handset processing means 48 takes note of the time as recorded by real-time clock 64 and instructs the processing means 28 to take note of the time as recorded by real-time clock 64. Both values are then stored in the respective processing means' 28, 48 associated transitional memory 38, 66 for later reference.

[0052] The processing means 28 then sends commands to initiate operation of the MEMS gyroscope 22, accelerometers 24 and temperature sensor 26. The processing means 28 thereafter operates to poll each of these components at regular intervals to obtain their current measurement values.

[0053] The driller then floats the downhole component 62 of the multi-purpose orientation system 10 (i.e. the housing 18 and the components housed therein along with the inner tube 1) down by way of the wireline until it lands on the collar (not shown) of the outer tube 9. When the downhole component 62 reaches the collar, the driller manipulates the wireline until such time as the inner tube 1 is received within the core barrel 7. When properly inserted, the inner tube 1 is locked in position within the core barrel 7.

[0054] On detection that the inner tube 1 is locked to the core barrel 7, the processing means 28 immediately polls the components of the first measuring subsystem 12 for their current measurement values. On receiving the measurement values from these components, the processing means 28 operates to determine the azimuth and dip measurement of the borehole 8. As the means to determine these calculations from gyroscopes and accelerometers is well known to the person skilled in the art, the specific process of transforming the measurement values to the azimuth and dip measurements will not be described in more detail here.

[0055] The calculated azimuth and dip measurements are then stored to an appropriate section of storage means 30 for later reference.

[0056] It is to be noted that during the process of lowering the downhole component 62 to the drill bit 3 and locking the inner tube 1 to the core barrel 7, no actual drilling of a core sample takes place. Furthermore, in this embodiment, the driller allows some time to pass between the locking of the inner tube 1 to the core barrel 7 and the commencement of drilling of the core sample to ensure that the calculated azimuth and dip measurements are taken during a period of drill silence.

[0057] The driller then commences drilling of the core sample. Friction generated during the process of drilling the core sample operates to keep the inner tube 1 (into which the core sample is received) in a known fixed position relative to the position of the second measuring subsystem 14.

[0058] At periodic intervals during the process of drilling the core sample, the processing means 28 operates to poll the tri-axial accelerometers 24 and temperature sensor 26 for their respective measurement values. Using the accelerometer 24 measurements, and compensating for the borehole temperature as determined by the temperature sensor 26, the processing means 28 operates to determine the orientation of the inner tube 1 (and by extension the core sample) and stores this value in an appropriate section of storage means 30 for later reference along with the time value recorded by real-time clock 36.

[0059] This process of obtaining measurements from the second measuring subsystem 14 repeats itself until a trigger event is detected. In this embodiment, the trigger event is the commencement of breaking of the core sample.

[0060] When the driller believes that an appropriate length of core sample has been drilled, the driller operates the appropriate procedures to break the core sample. This includes pressing the appropriate button on the handset 20 to indicate that the core is to be broken. In doing so, the handset processing means 48, obtains the current time from its real-time clock 56 and stores this value for later reference in handset storage means 50.

[0061] When the core is finally broken, the downhole component 62 is retrieved to the surface with the inner tube 1 (and core sample) attached thereto.

[0062] On return to the surface, the downhole component 62 and the handset seek to re-establish a communications channel between handset communication means 52 and communication means 32. Once the communications channel has been re-established, the driller then uses the interface means 46 to retrieve the borehole and core orientation measurements.

[0063] To obtain the borehole orientation measurement, the driller simply issues appropriate commands to the interface means 46 to show same. In response the handset processing means 48 queries the processing means 28 to return the azimuth and dip measurements stored in the appropriate section of the storage means 30. These values are then displayed to the driller by way of the display unit 56.

[0064] To obtain the core orientation measurement, the driller places the downhole component and attached inner tube 1 in a core tray (not shown). The driller then issues appropriate commands to the interface means 46 to perform a core re orientation.

[0065] Initiating core re-orientation causes the handset processing means 48 to retrieve from memory the time value stored in handset storage means at which the driller indicated that the process of breaking the core commenced. The handset processing means 48 then communicates this time value to the processing means 28 which cross-references the time value with the time values associated with the core orientation measurements stored in storage means 30. When a correlating match is found, the processing means 28 then returns the associated core orientation measurement to the handset processing means 48 which stores it in handset storage means 50 as the reference core orientation measurement.

[0066] The handset processing means 48 then enters a repetitive processing loop with processing means 28 whereby the processing means 28 constantly updates the handset processing means 48 as to its current orientation measurements (as taken by the second measuring subsystem) while being rotated or otherwise manipulated by the driller. In response, the handset processing means 48 compares the current orientation measurement against the reference core orientation measurement to determine the direction in which the downhole component 62 should be rotated in order to achieve re-orientation or whether re-orientation has been achieved. In either case, the driller is then advised of this current re-orientation state by way of display unit 56 so that further action, as required, can be taken.

[0067] When the downhole component 62 has been appropriately re-oriented, the driller then operates to mark the core as per normal practice.

[0068] In accordance with a second embodiment of the present invention, where like numerals reference like parts, there is a multi-purpose orientation system 200. The multi-purpose orientation system 200 is identical to multi-purpose orientation system in its physical construction.

[0069] While identical in physical construction, in this embodiment storage means 30 has a first section 202 for storing measurements taken by the first measuring subsystem 12 and a second section 204 for storing measurements taken by the second measuring subsystem 14. The second section 204 comprises an array of finite length.

[0070] This second embodiment of the invention will now be described in the context of its intended use.

[0071] A driller (not shown) screws the inner tube to second end 44 such that there their respective threaded portions (not shown) mate. The driller then moves to the first end 42 and attached a wireline thereto.

[0072] With the housing 18 now ready for insertion into the drill string 2, the driller now initiates configuration of the multi-purpose orientation system 10. To do so, the driller retrieves the handset 20 and, using the interface means 46, operates to set the operational parameters for this drill run. It should be appreciated by the person skilled in the art that the operational parameters are varied and not necessarily relevant to the invention as described herein. However, examples of specific operational parameters are provided in more detail below.

[0073] Once the operational parameters for the drilling run have been set, the driller initiates operation of the multi-purpose orientation system 200. This commences with the handset communication means 52 establishing a communications channel with communication means 32. Following establishment of this communications channel, the handset processing means 48 operates to send the operational parameters entered by the driller, as relevant to processing means 28, to the processing means 28 for storage and reference in transitional memory 38.

[0074] The processing means 28 then sends commands to initiate operation of the MEMS gyroscope 22, accelerometers 24 and temperature sensor 26. The processing means 28 thereafter operates to poll each of these components at regular intervals to obtain their current measurement values.

[0075] The driller then floats the downhole component 62 of the multi-purpose orientation system 10 (i.e. the housing 18 and the components housed therein) down by way of the wireline until it lands on the collar (not shown) of the outer tube 9. When the downhole component 62 reaches the collar, the shape of the collar centres the inner tube 1 and directs it towards the core barrel 7. In this manner, the inner tube 1 is ultimately received within the core barrel 7 and, when properly inserted, the inner tube 1 is locked in position within the core barrel 7.

[0076] On detection that the inner tube 1 is locked to the core barrel 7, the processing means 28 immediately polls the components of the first measuring subsystem 12 for their current measurement values. On receiving the measurement values from these components, the processing means 28 operates to determine the azimuth and dip measurement of the borehole 8. As the means to determine these calculations from gyroscopes and accelerometers is well known to the person skilled in the art, the specific process of transforming the measurement values to the azimuth and dip measurements will not be described in more detail here.

[0077] The calculated azimuth and dip measurements are then stored to first section 202 of storage means 30. The processing means 28 then send a control signal to MEMS gyroscope 22 to shutdown.

[0078] It is to be noted that during the process of lowering the downhole component 62 to the drill bit 3 and locking the inner tube 1 to the core barrel 7, no actual drilling of a core sample takes place. Furthermore, in this embodiment, the driller allows some time to pass between the locking of the inner tube 1 to the core barrel and the commencement of drilling of the core sample to ensure that the calculated azimuth and dip measurements are taken during a period of drill silence.

[0079] The driller then commences drilling of the core sample. Friction generated during the process of drilling the core sample operates to keep the inner tube 1 (into which the core sample is received) in a known fixed position relative to the position of the second measuring subsystem 14.

[0080] At periodic intervals during the process of drilling the core sample, the processing means 28 operates to poll the tri-axial accelerometers 24 and temperature sensor 26 for their respective measurement values. Using the accelerometer 24 measurements, and compensating for the borehole temperature as determined by the temperature sensor 26, the processing means 28 operates to determine the orientation of the inner tube 1 (and by extension the core sample) and stores this value in second storage section 204 of storage means 30.

[0081] This process of obtaining measurements from the second measuring subsystem 14 repeats itself until a trigger event is detected. In this embodiment, the trigger event is pull-back of the drill string 2.

[0082] Due to the finite nature of the array forming second storage section 204, if a new orientation measurement is to be stored when the array is full, the new orientation measurement overwrites the oldest measurement value stored in the array. In this embodiment, the oldest measurement value stored in the array is determined by the position of the measurement in the queue.

[0083] To elaborate, on being required to store a new orientation measurement, the processing means 28 may operate to shift each stored orientation measurement down one position in the array (with the last measurement being deleted if the array is full). The new orientation measurement is then stored in the first position of the array.

[0084] When the driller believes that an appropriate length of core sample has been drilled, the driller operates the appropriate procedures to break the core sample. When the core is finally broken, the downhole component 62 is retrieved to the surface with the inner tube 1 (and core sample) attached thereto.

[0085] On return to the surface, the downhole component 62 and the handset seek to re-establish a communications channel between handset communication means 52 and communication means 32. Once the communications channel has been re-established, the driller then uses the interface means 46 to retrieve the borehole and core orientation measurements.

[0086] To obtain the borehole orientation measurement, the driller simply issues appropriate commands to the interface means 46 to show same. In response the handset processing means 48 queries the processing means 28 to return the azimuth and dip measurements stored in the first storage section 202 of the storage means 30. These values are then displayed to the driller by way of the display unit 56.

[0087] To obtain the core orientation measurement, the driller places the downhole component and attached inner tube 1 in a core tray (not shown). The driller then issues appropriate commands to the interface means 46 to perform a core re orientation.

[0088] Initiating core re-orientation causes the handset processing means 48 to query processing means 28 to provide the orientation measurement stored in the first position of the array forming second storage section 204. The processing means 28 then returns the associated core orientation measurement to the handset processing means 48 which stores it in handset storage means 50 as the reference core orientation measurement.

[0089] The handset processing means 48 then enters a repetitive processing loop with processing means 28 whereby the processing means 28 constantly updates the handset processing means 48 as to its current orientation measurements (as taken by the second measuring subsystem) while being rotated or otherwise manipulated by the driller. In response, the handset processing means 48 compares the current orientation measurement against the reference core orientation measurement to determine the direction in which the downhole component 62 should be rotated in order to achieve re-orientation or whether re-orientation has been achieved. In either case, the driller is then advised of this current re-orientation state by way of display unit 56 so that further action, as required, can be taken.

[0090] When the downhole component 62 has been appropriately re-oriented, the driller then operates to mark the core as per normal practice.

[0091] In the above embodiments, two examples of potential trigger events that may be used to determine when to stop recording orientation measurements have been given. However, there is no reason why other trigger events may be used, for instance, any of the following may also be used as an appropriate trigger event:

• Acceleration of the downhole component 62; • Change in rotational direction of the core drill;

• Change in direction of motion of the downhole component 62 from a downhole direction to an uphole direction; • A backend assembly (not shown) being released at the collar of the borehole; • The backend assembly hitting a water table at the toe of the hole; • The backend assembly contacting or hitting a landing ring; • Commencement of drilling; • Cessation of drilling; • An overshot hitting and latching onto the backend assembly; • Detecting flow of fluid through or around the backend assembly; AND * The expiry of a set time period from a specified reference time or trigger event.

[0092] Furthermore, while the above embodiments have been described in the context of the trigger event being a single action, the trigger event could be a pattern of events or multiple events whether detected in a specified sequence or otherwise.

[0093]It should be appreciated by the person skilled in the art that the above invention is not limited to the embodiment described. In particular, the following modifications and improvements may be made without departing from the scope of the present invention:

• [0094] The first measuring subsystem 12 may comprise of other measuring devices than the MEMS gyroscope 22 and accelerometers 24 as would be known by the person skilled in the art as applicable to measuring the orientation of a borehole. • [0095] Similarly, the second measuring subsystem 14 may comprise of other measuring devices than the accelerometers 24 and temperature sensor 26 as would be known by the person skilled in the art as applicable to measuring the orientation of an attached article (i.e. inner tube). • [0096] The first measuring subsystem 12 may calculate its azimuth value from appropriate Northing and Easting readings. • [0097] The first measuring subsystem 12 and/or second measuring subsystem 14 may be used to measure other characteristics of the borehole or drilling operation, such as top dead centre of the borehole. • [0098] In a preferred arrangement, to save power, processing means 28 may operate to shutdown MEMS gyroscope 22 following storage in storage means 30 of the borehole orientation measurements from the first measuring subsystem 12. • [0099] Real-time clocks 36, 56 may be substituted for synchronised stop watches. Synchronisation, in this context, does not require the real-time clocks 36, 56 to be recording the exact same time, but have a sufficiently known time offset so as to allow the processing means 28, 48 to make adjustments as required to ensure correct correlation of core orientation measurements. • [0100] The storage means 30 may be removable. However, as this means that the downhole component 62 cannot be a sealed unit, this is not preferable. • [0101] The communication means 32, 52 may use any form of wireless communication technology or communications protocol, for instance, the communication means 32, 52 may communicate using infra-red signals. Furthermore, the communication means 32, 52 need not communicate wirelessly, but this again means that the downhole component 62 cannot be a sealed unit. • [0102] The handset 20 may be replaced with a general purpose device such as a smart phone, notebook computer or tablet. In such arrangements, the keypad 58 may be a virtual keypad. Thus, the handset 20 may be more appropriately be referred to as a surface communications device. • [0103] The power means 34 may be modified to allow recharging through other arrangements than induction charging as would be readily known to the person skilled in the art. However, as this again brings into play the situation where the downhole component 62 may not be a sealed unit, induction charging arrangements are preferred. • [0104] The operational parameters entered by the driller prior to commencement of a drilling run may include descriptive factors such as hole reference, GPS co-ordinates, time and date, intended drill depth and even general comments regarding the hole or drilling conditions. • [0105] The operational parameters entered by the driller may include operational factors such as the amount of time to wait before commencing operation of the first and second measuring systems 12, 14.

• [0106] The re-orientation process may incorporate visual cues, displayed to the driller by way of display unit 56 to facilitate re-orientation. These visual cues may include an arrow or directional graphic to indicate the direction that the downhole component 62 must be rotated in order to achieve re-orientation or a flashing light the speed of which reflects how close the downhole component 62 is to being re-oriented. • [0107] The re-orientation process may incorporate audio cues that are played to the driller to facilitate re-orientation. For example, the audio cue may be a reference to the direction and/or extent to which the downhole component 62 must be rotated in order to achieve re-orientation. • [0108] In a variation of the first embodiment, the real-time clocks 36, 56 need not be synchronised prior to operation of the downhole component 62. Rather, the handset unit may operate to record the time that elapses from the driller indicating that the core is to be broken to the time that the downhole component 62 re-establishes a communications channel with the handset 20. The processing means 28 can then seek to cross-reference the time measurements by subtracting this elapsed time measurement from the current time value recorded by real-time clock 36 to determine the time determined by the processing means 28 indicative of core break. • [0109] The secondary measuring system 14 may be shutdown on detection of a trigger event as already described. The shutdown may occur immediately on detection or after a set period of time following detection. • [0110] The reference core orientation measurement returned to the processing means 48 by processing means 28 in the second embodiment of the invention may be a processed value indicative of what the system considers to be the true indication of the orientation of the core. In this respect, the process used could be an average, weighted average, mode or mean function. * [0111] Ideally, the driller maintains a period of drill silence in which at least two core orientation measurements may be taken by the accelerometers 24. Furthermore, it is preferable that the number of elements in the array of the second embodiment be equal to the expected period of drill silence divided by the interval period for taking core orientation measurements by accelerometers 24.

• [0112] A vibration sensor, or other form of movement sensor, may act as a filter for measurement values taken by either the first or second measuring systems 12, 14. In such situations, if the vibration sensor determines that there is movement above a pre-defined tolerance level, the measurement value obtained from either the first or second measuring system 12, 14 will be discarded (ie. not stored in storage means 30) or treated as not having been taken.

• [0113] In a variation on the second embodiment, a memory card may be used to record all measurement data. In this manner, the measurement data written to the storage means 30 is simultaneously written to the memory card. In this manner, as no measurements are overwritten on the memory card, the memory card can act as a full audit trail of core orientation measurements taken by the multi-purpose orientation system 200.

• [0114] In the first and second embodiments of the invention described above, each processed orientation measurement stored in memory may be correlated to a time value indicative of the time the measurement was taken. In this manner, the operator can verify that the measurements provided by the system have actually been obtained at the desired time interval and not before or subsequent.

* [0115] In a variation of the embodiment described, the processing means 28 does not operate to poll the components of the first measuring subsystem 12 for their current measurement values immediately on detection that the inner tube 1 is locked to the core barrel 7. Rather, the processing means 28 may operate to poll the components of the first measuring system 12 a preset period of time after detection that the inner tube 1 is locked to the core barrel 7. This preset period may be defined by the operator as part of the setting of the operational parameters.

• [0116] The processing means 28 may operate to poll the components of the first measuring subsystem 12 multiple times after detecting that the inner tube 1 is locked to the core barrel 7. The processing means 28 may then operate to provide all such measurements as indications as to the orientation of the borehole, or process the measurements using proprietary algorithms to arrive at a single measurement set representative of the orientation of the borehole.

• [0117] The processing means 28 may detect that the inner tube 1 is locked to the core barrel 7 in a variety of ways as would be readily apparent to the person skilled in the art. For instance, one means of detecting that the inner tube 1 is locked to the core barrel 7 is by the presumption that cessation of movement of the downhole component 62 for a certain length of time is indicative of the inner tube 1 being locked to the core barrel. An alternative means of detecting that the inner tube 1 is locked to the core barrel 7 can be by way of a mechanical switch or electronic sensor that is activated in such circumstances.

• [0118] The processing means 28 may also operate to wait a preset period of time before polling or querying the second measuring subsystem 14 for measurement data. This preset period may be defined by the operator as part of the setting of the operational parameters. However, a default preset period of twenty (20) minutes may be used as the applicant is of the view that this allows a driller to obtain core orientation measurements even in situations where the core need be broken early.

• [0119] It is to be appreciated by the person skilled in the art that the embodiment described above represents use of the invention in a dry hole. Where the invention is to be used in a wet hole, the operator may float the downhole component 62 down the hole through normal gravitational forces and without the assistance of a wireline.

* [0120] While the invention has been described in the context of a threaded engagement between downhole unit 62 and inner tube 1, other connecting methods can be used. These include other mechanical means of connection or non-mechanical means (such as magnetic connections).

• [0121] The method of locking the inner tube 1 to the core barrel 7 can vary as is necessary to accommodate the intended use of the downhole component 62 and the environment in which it is to operate. However, as examples, the downhole component 62 may incorporate mechanical means, such as a locking pin, that is physically received in a recess channel of the core barrel 7. Retention of the locking pin, or other mechanical means, in the recess channel (or an alternative retaining mechanism or structure) is then preferably achieved by means of forces generated during the process of drilling the core sample. Other locking systems, such as electronic sensors, may be used to detect the presence of the core barrel 7 and, on detection, initiate some sort of locking sequence.

* [0122] In a variation of the configuration discussed in the last paragraph, the electronic sensors used to detect the presence of the core barrel 7 with the intent to initiate some sort of locking sequence can also be used as the means for detecting that the inner tube 1 is locked to the core barrel 7.

[0123] It should be further appreciated that even more embodiments of the invention incorporating one or more of the aforementioned features, where such features are not mutually exclusive, can be created without departing from the invention's scope.

Claims

We Claim:

1. A multi-purpose orientation measurement system comprising:

a surface communications device; and

a downhole unit, the downhole unit having a first measuring subsystem for measuring borehole orientation and a second measuring subsystem for measuring core orientation,

where the downhole unit is adapted to fixedly engage an inner tube and where, in use, when the downhole unit detects that the inner tube has been received within a core barrel, the downhole unit stores measurements taken by the first measuring subsystem relating orientation of the borehole and thereafter, store measurements taken by the second measuring subsystem indicative of the orientation of the fixedly attached inner tube, the downhole unit then operable to communicate the stored measurements to the surface communications device on return of the downhole unit to the surface.

2. A multi-purpose orientation measurement system according to claim 1, where the first measuring subsystem comprises a gyroscope and triaxial accelerometers for determining azimuth and dip measurements.

3. A multi-purpose orientation system according to claim 1 or claim 2, where the second measuring subsystem comprises triaxial accelerometers and a temperature probe.

4. A multi-purpose orientation system according to claim 3, as dependent on claim 2, where the triaxial accelerometers of the first measuring subsystem also constitute the triaxial accelerometers of the second measuring subsystem.

5. A multi-purpose orientation system according to any preceding claim, further comprising a first storage means and a second storage means, the measurements taken by the first measuring subsystem operable to be stored in the first storage means and measurements taken by the second measuring subsystem operable to be stored in the second storage means.

6. A multi-purpose orientation system according to claim 5, where the second storage means operates to store measurements from the second measuring subsystem in a queue on a first in, first out basis.

7. A multi-purpose orientation measurement system according to claim 1 or claim 2, where the downhole unit has processing means for detecting a trigger event, the processing means operable to shutdown the second measuring system on detection of the trigger event.

8. A method of obtaining orientation measurements during drilling comprising the steps of:

on detecting that the inner tube is received within the core barrel:

9. The method of claim 8, further including the step of setting operational parameters for the drilling run by way of the surface communications device, the surface communications device thereafter operable to communicate the operational parameters to the downhole unit.

1O.The method of claim 8 or claim 9, further including the step of waiting a predetermined period of time between storing measurements taken by the first measuring subsystem and storing measurements taken by the second measuring subsystem.

11.The method of any one of claims 8 to 10, further including the step of waiting a predetermined period of time between detecting that the inner tube is received within the core barrel and the step of storing measurements taken by the first measuring subsystem.

12. The method of any one of claims 8 to 11, further including the step of shutting down the first measuring subsystem after storing measurements obtained therefrom.

13.The method of any one of claims 8 to 12, further including the steps of detecting a trigger event and, on detection of the trigger event, shutting down the second measuring subsystem.

14.The method of any one of claims 8 to 13, where the measurements taken by the first measuring subsystem include measurements from which azimuth and dip can be calculated.

15.The method of any one of claims 8 to 14, where the step of storing measurements taken by the first measuring subsystem are stored in a first storage means and the step of storing measurements taken by the second measuring subsystem are stored in a second storage means.

16.The method of any one of claims 8 to 15, further including the step of positioning the downhole unit involves using the shape of a collar to guide the inner tube into place within the core barrel and centre it therein.