CA3034082A1 - Method of obtaining borehole and core orientation measurements in a single run and apparatus for performing the method - Google Patents

Abstract

A method of obtaining borehole and core orientation measurements in a single run comprising the steps of: lowering an orientation measurement device (10) connected to an inner tube (3) to a drilling position; measuring the orientation measurement device's (10) position in three-dimensional space at the drilling position;
commencing periodic measurement of the orientation of the inner tube (3) by reference to a measurement of the roll angle orientation of the orientation measurement device (10);
and determining the orientation of the inner tube (3) just prior to a trigger event.

Description

"METHOD OF OBTAINING BOREHOLE AND CORE ORIENTATION
MEASUREMENTS IN A SINGLE RUN AND APPARATUS FOR PERFORMING
THE METHOD"
FIELD OF THE INVENTION
[0001] The invention relates to a method of obtaining borehole and core orientation measurements in a single run and apparatus for performing the method.
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] One object of a drilling programme is to map the locations of any ore bodies that may be identified. In order to determine such location, a geologist typically needs two pieces of information relating to each drill hole ¨ the orientation of the borehole and the orientation of each core sample retrieved from the drill hole.

[0004] At present, each of these measurements is obtained by way of a separate downhole process.

[0005] The orientation of each core sample is typically measured by using a core orientation device attached to the inner tube of the drill string.
Various forms of core orientation devices are known to the person skilled in the art, but in more recent years core orientation devices have become electronic devices which use accelerometers to determine the tool-face angle of the inner tube to which it is attached.

[0006] By contrast, the orientation of the borehole is typically measured using a separate borehole orientation tool which is run down the drill string taking periodic measurements of the borehole's location in three dimensional space.
Traditionally, such tools have used accelerometers and magnetometers, but gyroscopes have become more prevalent in recent years.

[0007] As the performance of two separate downhole processes is time consuming, and therefore also expensive when the cost of running drilling equipment is factored in, it is of great benefit if it is possible to obtain both measurements as part of a single downhole process. Imdex Global B.V. of Amsterdam-Zuidoost, The Netherlands has sought to achieve such an aim with the invention described in W02017/127885 (hereafter the "Imdex Application").

[0008] The Imdex Application describes a system whereby a borehole survey tool is run down the drill string and attaches itself to the inner tube.
During this run, the borehole survey tool operates to measure its position in three-dimensional space (and by extension thus the borehole's position in three-dimensional space).
Once attached to the inner tube, the borehole survey tool is able to query a sensor or other system provided in the inner tube. The sensor or system either provides data back to the borehole survey tool from which the tool-face angle of the inner tube can be determined or provides the determined tool-face angle direct to the borehole survey tool.

[0009] The problem with this arrangement is that the system forms multiple parts. A failure by the driller to use either the specialised inner tube or the correct borehole survey tool will result in an inability to obtain a measurement of the inner tube. This use of multiple parts, as well as potentially mechanical structures to prevent rotation of the inner core during drilling, makes the device prone to failure and adds complexity to the method.
SUMMARY OF THE INVENTION

[0010] 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".

[0011] In accordance with a first aspect of the present invention there is a method of obtaining borehole and core orientation measurements in a single run comprising the steps of:
lowering an orientation measurement device connected to an inner tube to a drilling position;
measuring the orientation measurement device's position in three-dimensional space at the drilling position;

commencing periodic measurement of the orientation of the inner tube by reference to the orientation fo the orientation measurement device; and determining the orientation of the inner tube just prior to a trigger event.

[0012] Preferably, the step of measuring the orientation measurement device's position in three-dimensional space at the drilling position occurs prior to the commencement of periodic measurement of the orientation of the inner tube.

[0013] To ensure that the orientation measurement device is able to properly measure the orientation of the inner tube, it is desired to include a further step of locking the orientation measurement device to the inner tube in a fixed rotational arrangement. In this manner, any rotational change in the inner tube is reflected by a corresponding rotational change in the orientation measurement device and thus recording the orientation of the orientation measurement device equates to a measurement of the orientation of the inner tube.

[0014] Periodic measurement of the orientation of the inner tube may occur for a set number of measurements, or be continuous. Where the orientation measurement device is configured so as to store a set number of measurements of the orientation of the inner tube, once this storage capacity has been written, the orientation measurement device may cease taking measurements or start writing over existing measurements on a historical basis. Alternatively, or cumulatively, periodic measurement of the orientation of the inner tube ceases when the trigger event occurs.

[0015] The trigger event may be the start or cessation of an action or other event. For instance, the trigger event may be the exact time when the overshot is attached to the orientation measurement device. Alternatively, the trigger event may be the expiry of a defined time period.

[0016] To prevent the inner tube from rotating during the course of drilling of the core, the method may further include the step of rotationally disengaging the inner tube from the outer tube.

[0017] In accordance with a second aspect of the present invention there is an orientation measurement device comprising:
a first measurement system; and a second measurement system;
where, on reaching a drilling position, the first measurement system measures the orientation measurement device's position in three dimensional space and the second measurement system commences periodic measurement of the orientation of the inner tube.

[0018] The orientation measurement device may operate such that the second measurement system does not commence periodic measurement of the orientation of the inner tube until after the first measurement system has measured the orientation measurement device's position in three dimensional space.

[0019] The orientation measurement device may further comprise rotational locking means, the rotational locking means operable to ensure that any rotation imparted to the inner tube is similarly imparted to the orientation measurement device.

[0020] The second measurement system may further include a fixed size memory for recording periodic measurements of the orientation of the inner tube. Measurements recorded in the fixed size memory may be overwritten on a historical basis.

[0021] The second measurement system may further operate to determine the orientation of the inner tube prior to a trigger event. The trigger event may be the start or cessation of an action or event. Furthermore, or alternatively thereto, the second measurement system may cease periodic measurement of the orientation of the inner tube on detection of the trigger event.

[0022] The orientation measurement device may further comprise rotational disengagement means, the rotational disengagement means operable to ensure that rotation of the outer tube occurs independently of the orientation measurement device and attached inner tube.

[0023] In accordance with a third 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.

[0024] Preferably, the first measuring subsystem comprises a gyroscope and triaxial accelerometers for determining azimuth and dip measurements.

[0025] 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.

[0026] In accordance with a fourth 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.

[0027] 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 down hole unit.

[0028] 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.

[0029] 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.

[0030] Preferably, the method includes the step of shutting down the first measuring subsystem after storing measurements obtained therefrom.

[0031] 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.

[0032] Preferably the measurements taken by the first measuring subsystem include measurements from which azimuth and dip can be calculated.
BRIEF DESCRIPTION OF THE DRAWINGS

[0033] 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 an orientation measurement device installed in a drill string.
Figure 3 is a schematic representation of the orientation measurement device shown in Figure 2.
Figure 4 is a schematic representation of a third embodiment of the present invention.

Figure 5 is a schematic representation of a downhole unit as used in a fourth embodiment of the present invention.
PREFERRED EMBODIMENTS OF THE INVENTION

[0034] In accordance with a first embodiment of the present invention there is an orientation measurement device 10. The orientation measurement device 10 is intended to be used in a drill string 2. The drill string 2 comprises an outer tube 8, an inner tube 1 and a drill head 9. The drill head 9 is connected to the outer tube 8.

[0035] The orientation measurement device 10 comprises a housing 12. A
first end 14 of the housing 12 is threaded to allow attachment of the inner tube 3.
A second end 16 of the housing 12 is configured so as to allow the orientation measurement device 10 (with attached inner tube) to be lowered down the drill string 1.

[0036] Located within the housing 12 is a first measurement system 18 and a second measurement system 20 and a trigger sensing system 22.

[0037] In this embodiment, the first measurement system 18 comprises a gyroscope 24. The gyroscope 24 is operable to measure, in essence, the housing's 12 position in three-dimensional space. This measurement takes the form of an inclination measurement and a Northerly-Easterly measurement.

[0038] The second measurement system 20 comprises tri-axial accelerometers 26, tri-axial magnetometers 28 and a temperature sensor 30. The tri-axial accelerometers 26, tri-axial magnetometers 28 and temperature sensor 30 operate to measure the roll angle of the housing 12. As the inner tube 3 is threadedly attached to the first end 14 of the housing, the roll angle orientation measurement of the housing 12 also reflects the roll angle orientation measurement of the inner tube 1.

[0039] The trigger sensing system 22 in this embodiment takes the form of a movement sensor 32 and a connection sensor 34.

[0040] The first measurement system 18, second measurement system 20 and trigger sensing system 22 are connected to a processing system 36. The processing system 36 comprises a processor 38, storage memory 40 and a communications device 42.

=

[0041] A power unit, in the form of a battery pack 44, supplies power to the first measurement system 18, second measurement system 20, trigger sensing system 22 and processing system 36.

[0042] The orientation measurement device 10 may further be adapted for use with rotational disengagement means 46. The rotational disengagement means 46 operates to prevent rotational movement of the outer tube 2 being imparted to the housing 12 (and by extension the inner tube 3).

[0043] To elaborate, the rotational disengagement means 46 comprises a plurality of lever arms 48. Each lever arm 48 is pivotally connected to a corresponding pivot frame 50. The pivot frame 50 is mounted to the outer tube 8.

[0044] This first embodiment of the invention will be further described in the context of its intended use.

[0045] A driller (not shown) threads an inner tube 1 onto the first end 14 of the housing 12. Once so threaded, the inner tube 1 and the housing 12 remain in a fixed rotational arrangement with each other until such time as the driller unthreads the two components. The driller then runs the assembled unit down the drill string 2 in the manner as would be readily known to the person skilled in the art.

[0046] When the assembled unit reaches the end of the drill string 2 it is locked in place as is required of a normal inner tube having an electronic core orientation measurement device attached.

[0047] The process of locking the assembled unit in place is detected by the connection sensor 34. In response to this detection, the connection sensor 34 causes the gyroscope 24 to take a measurement of its position in three-dimensional space (and thus, by extension, the position of the end of the borehole in three-dimensional space). This measurement is then provided to the processing system 36 which stores the component parts of this measurement in storage memory 40.

[0048] It is to be noted that at this time, the lever arms 48 pivot freely about their pivot frames 50. In this context, gravity determines the direction of the lever arm 48 relative to the pivot frame 50.

[0049] Because the measurement taken by the gyroscope 24 is taken so quickly after connection, it typically occurs before the drill head 9 commences drilling of the core sample and thus the measurement is no impacted by the rotational forces associated with drilling.

[0050] While the frictional engagement caused by the core sample entering and travelling along the inner tube 1 typically results in the inner tube 1 being stationary relative to the rotational movement of the outer tube 8 and drill head 9, the lever arms 48 ensure that the inner tube 1 remains stationary. To elaborate, the centrifugal forces generated by the rotation of the outer tube 8 and drill head 9 causes one end 52 thereof to pivot about pivot frame 50 towards the outer tube 8. In doing so, opposing end 54 of the lever arm 48 to make contact with, and apply pressure to, the inner tube 1. As this pressure is applied at multiple points of contact, the inner tube 1 thereby resists rotational movement otherwise imparted during drilling of the core sample.

[0051] At the same time, immediately after taking the gyroscopic measurement, the processor 38 sends relevant commands to the second measurement system 20.
The second measurement system 20 operates to send measurements from the tri-axial accelerometer 26, tri-axial magnetometers 28 and temperature sensor 30 back to the processor 38. The processor 38 then operates to process these measurements so as to determine the tool-face orientation of the housing 12 and, by extension, the inner tube 1. The actual calculations required to obtain a tool-face orientation measurement from the measurements taken from the tri-axial accelerometers 26, tri-axial magnetometers 28 and temperature sensor 30 is now well known to the art and one example of such calculations are provided in Australian Patent Application 2005256104 entitled "Core sample orientation" owned by Australian Mud Company Ltd.

[0052] The processed measurement is then stored in storage memory 40.
Because the storage memory 40 has limited space for storing such processed measurements, when the storage memory 40 is full, further processed measurements are stored by overwriting earlier processed measurements on a historical basis. Thus, the storage memory 40 only records the most recent processed measurements at all times.

[0053] While the second measurement system 20 is taking and storing tool-face orientation measurements, the movement sensor 32 continually monitors for an action consistent with continued upwards movement of the orientation device 10. When such movement is detected, the movement sensor 10 assumes that the orientation device 10, with inner tube 1 attached thereto, is being retrieved and sends a signal to the processor 38. On receipt of this signal, the processor 38 sends a further signal to the second measurement system 20 to shutdown.

[0054] When the orientation measurement device 10, with inner tube 1 attached, is retrieved to the surface the driller then operates a topside communications device (not shown) to establish a communication link with the orientation measurement device 10 by way of communications device 42. Once the communication link has been established, the topside communications device (not shown) downloads from storage memory 40 the processed measurements and gyroscopic measurements. The geologist, or other drilling professional, then utilises these measurements as, respectively, the core orientation measurement and borehole orientation measurement.

[0055] In accordance with a third embodiment of the invention there is a multi-purpose orientation system 300. The multi-purpose orientation system 300 comprises:
= a first measuring subsystem 312 for measuring the orientation of a borehole;
= a second measuring subsystem 314 for measuring the orientation of a connected inner tube 1;
= a control and storage subsystem 316;
= a housing 318;
= a handset 320.

[0056] The first measuring subsystem 312 comprises a vibrating structure gyroscope incorporating microelectromechanical systems technology 322 (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.

[0057] The second measuring subsystem 314 comprises the tri-axial accelerometers 324 and a temperature sensor 326.

[0058] The control and storage subsystem 316 is in data and control communication with the first measuring subsystem 312 and the second measuring subsystem 314. The control and storage subsystem 16 comprises:
= processing means 328;
= storage means 330;
= communication means 332; and = power means 334.

[0059] The processing means 328 is in data communication with the storage means 330 and in data and control communication with the communication means 332. The processing means 328, storage means 330 and communication means 332 are all powered by the power means 334.

[0060] The processing means 328 incorporates a real-time clock 336 and transitional memory 338.

[0061] The storage means 330, in this embodiment, takes the form of a solid-state storage device. The storage means 330 is in fixed position.

[0062] The communication means 332 takes the form of a wireless communications unit 340 operating under the BluetoothTM communications protocol.
The wireless communications unit 340 is a two-way communications system, allowing it to both transmit and receive BluetoothTM signals.

[0063] The power means 334 takes the form of a rechargeable battery.
The power means 334 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.

[0064] The first measuring subsystem 312, second measuring subsystem and control and storage subsystem 316 are all contained within housing 318. In this embodiment, cushioning (not shown) is provided in the housing to ensure that the first measuring subsystem 312, second measuring subsystem 314 and control and storage subsystem 316 are not subjected to excessive force during drilling.

[0065] The housing 318 is cylindrical in shape and has a first end 342 and a second end 344. First end 342 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 344 is adapted to facilitate connection of the inner tube 1 by way of a screw thread.

[0066] 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.

[0067] The handset 320 comprises interface means 346, handset processing means 348, handset storage means 350, handset communication means 352 and handset power means 354.

[0068] Interface means 346 comprises a display unit 356 and a keypad 358.

[0069] Handset processing means 348 is in data communication with the handset storage means and in data and control communication with the interface means 346 and handset communication means 352. The interface means 346, the handset processing means 348, handset storage means 350 and handset communication means 352 are all powered by the power means handset 354.

[0070] The handset processing means 348 incorporates a real-time clock and transitional memory 366.

[0071] The handset storage means 350, in this embodiment, again takes the form of a solid-state storage device. The storage means 330 is removable form the housing 368 which contains the interface means 346, handset processing means 348, handset storage means 350, handset communication means 352 and handset power means 354.

[0072] The handset communication means 352 takes the form of a wireless communications unit 360 operating under the BluetoothTM communications protocol.
The wireless communications unit 360 is a two-way communications system, allowing it to both transmit and receive BluetoothTM signals.

[0073] The handset power means 354 takes the form of a rechargeable battery.
In this embodiment, the handset power means 354 is able to be recharged through mating power connectors (not shown) provided in the handset 320 and an associated docking cradle (not shown).

[0074] 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.

[0075] 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.

[0076] 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.

[0077] This first embodiment of the invention will now be described in the context of its intended use.

[0078] A
driller (not shown) screws the inner tube to second end 344 such that their respective threaded portions (not shown) mate. The driller then moves to the first end 342 and attached a wireline thereto.

[0079] With the housing 318 now ready for insertion into the drill string 2, the driller now initiates configuration of the multi-purpose orientation system 300. To do so, the driller retrieves the handset 320 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.

[0080] Once the operational parameters for the drilling run have been set, the driller initiates operation of the multi-purpose orientation system 300.
This commences with the handset communication means 352 establishing a communications channel with communication means 332. Following establishment of this communications channel, the handset processing means 348 operates to send the operational parameters entered by the driller, as relevant to processing means 328, to the processing means 328 for storage and reference in transitional memory 338.

[0081] At the same time, the handset processing means 348 takes note of the time as recorded by real-time clock 364 and instructs the processing means 328 to take note of the time as recorded by real-time clock 364. Both values are then stored in the respective processing means' 328, 348 associated transitional memory 338, 366 for later reference.

[0082] The processing means 328 then sends commands to initiate operation of the MEMS gyroscope 322, accelerometers 324 and temperature sensor 326. The processing means 328 thereafter operates to poll each of these components at regular intervals to obtain their current measurement values.

[0083] The driller then floats the downhole component 362 of the multi-purpose orientation system 300 (i.e. the housing 318 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 362 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 is locked in position within the core barrel 7.

[0084] On detection that the inner tube 1 is locked to the core barrel 7, the processing means 328 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 328 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.

[0085] The calculated azimuth and dip measurements are then stored to an appropriate section of storage means 330 for later reference.

[0086] 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.

[0087] 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 314.

[0088] At periodic intervals during the process of drilling the core sample, the processing means 328 operates to poll the tri-axial accelerometers 324 and temperature sensor 326 for their respective measurement values. Using the accelerometer 324 measurements, and compensating for the borehole temperature as determined by the temperature sensor 326, the processing means 328 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 330 for later reference along with the time value recorded by real-time clock 336.

[0089] This process of obtaining measurements from the second measuring subsystem 314 repeats itself until a trigger event is detected. In this embodiment, the trigger event is the commencement of breaking of the core sample.

[0090] 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 320 to indicate that the core is to be broken. In doing so, the handset processing means 348, obtains the current time from its real-time clock 356 and stores this value for later reference in handset storage means 350.

[0091] When the core is finally broken, the downhole component 362 is retrieved to the surface with the inner tube 1 (and core sample) attached thereto.

[0092] On return to the surface, the downhole component 362 and the handset 330 seek to re-establish a communications channel between handset communication means 352 and communication means 332. Once the communications channel has been re-established, the driller then uses the interface means 346 to retrieve the borehole and core orientation measurements.

[0093] To obtain the borehole orientation measurement, the driller simply issues appropriate commands to the interface means 346 to show same. In response the handset processing means 348 queries the processing means 328 to return the azimuth and dip measurements stored in the appropriate section of the storage means 330. These values are then displayed to the driller by way of the display unit 356.

[0094] 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 346 to perform a core re-orientation.

[0095] Initiating core re-orientation causes the handset processing means 348 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 348 then communicates this time value to the processing means 328 which cross-references the time value with the time values associated with the core-orientation measurements stored in storage means 330. When a correlating match is found, the processing means 328 then returns the associated core orientation measurement to the handset processing means 348 which stores it in handset storage means 350 as the reference core orientation measurement.

[0096] The handset processing means 348 then enters a repetitive processing loop with processing means 328 whereby the processing means 328 constantly updates the handset processing means 348 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 348 compares the current orientation measurement against the reference core orientation measurement to determine the direction in which the downhole component 362 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 356 so that further action, as required, can be taken.

[0097] When the downhole component 362 has been appropriately re-oriented, the driller then operates to mark the core as per normal practice.

[0098] In accordance with a fourth embodiment of the present invention, where like numerals reference like parts, there is a multi-purpose orientation system 400.
The multi-purpose orientation system 400 is identical to multi-purpose orientation system 300 in its physical construction.

[0099] While identical in physical construction, in this embodiment storage means 330 has a first section 402 for storing measurements taken by the first measuring subsystem 312 and a second section 404 for storing measurements taken by the second measuring subsystem 314. The second section 404 comprises an array of finite length.

[0100] This fourth embodiment of the invention will now be described in the context of its intended use.

[0101] A
driller (not shown) screws the inner tube to second end 344 such that there their respective threaded portions (not shown) mate. The driller then moves to the first end 342 and attached a wireline thereto.

[0102] With the housing 318 now ready for insertion into the drill string 2, the driller now initiates configuration of the multi-purpose orientation system 400. To do so, the driller retrieves the handset 320 and, using the interface means 346, 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.

[0103] Once the operational parameters for the drilling run have been set, the driller initiates operation of the multi-purpose orientation system 400.
This commences with the handset communication means 352 establishing a communications channel with communication means 332. Following establishment of this communications channel, the handset processing means 348 operates to send the operational parameters entered by the driller, as relevant to processing means 328, to the processing means 328 for storage and reference in transitional memory 338.

[0104] The processing means 328 then sends commands to initiate operation of the MEMS gyroscope 322, accelerometers 324 and temperature sensor 326. The processing means 328 thereafter operates to poll each of these components at regular intervals to obtain their current measurement values.

[0105] The driller then floats the down hole component 362 of the multi-purpose orientation system 400 (i.e. the housing 318 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 362 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.

[0106] On detection that the inner tube 1 is locked to the core barrel 7, the processing means 328 immediately polls the components of the first measuring subsystem 312 for their current measurement values. On receiving the measurement values from these components, the processing means 328 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.

[0107] The calculated azimuth and dip measurements are then stored to first section 402 of storage means 330. The processing means 328 then send a control signal to MEMS gyroscope 322 to shutdown.

[0108] It is to be noted that during the process of lowering the downhole component 362 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.

[0109] 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 314.

[0110] At periodic intervals during the process of drilling the core sample, the processing means 328 operates to poll the tri-axial accelerometers 324 and temperature sensor 326 for their respective measurement values. Using the accelerometer 324 measurements, and compensating for the borehole temperature as determined by the temperature sensor 326, the processing means 328 operates to determine the orientation of the inner tube 1 (and by extension the core sample) and stores this value in second storage section 404 of storage means 330.

[0111] This process of obtaining measurements from the second measuring subsystem 314 repeats itself until a trigger event is detected. In this embodiment, the trigger event is pull-back of the drill string 2.

[0112] Due to the finite nature of the array forming second storage section 404, 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.

[0113] To elaborate, on being required to store a new orientation measurement, the processing means 328 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.

[0114] 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 362 is retrieved to the surface with the inner tube 1 (and core sample) attached thereto.

[0115] On return to the surface, the downhole component 362 and the handset 330 seek to re-establish a communications channel between handset communication means 352 and communication means 332. Once the communications channel has been re-established, the driller then uses the interface means 46 to retrieve the borehole and core orientation measurements.

[0116] To obtain the borehole orientation measurement, the driller simply issues appropriate commands to the interface means 346 to show same. In response the handset processing means 348 queries the processing means 328 to return the azimuth and dip measurements stored in the first storage section 402 of the storage means 330. These values are then displayed to the driller by way of the display unit 356.

[0117] 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 346 to perform a core re-orientation.

[0118] Initiating core re-orientation causes the handset processing means 348 to query processing means 328 to provide the orientation measurement stored in the first position of the array forming second storage section 404. The processing means 328 then returns the associated core orientation measurement to the handset processing means 348 which stores it in handset storage means 350 as the reference core orientation measurement.

[0119] The handset processing means 348 then enters a repetitive processing loop with processing means 328 whereby the processing means 328 constantly updates the handset processing means 348 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 348 compares the current orientation measurement against the reference core orientation measurement to determine the direction in which the downhole component 362 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 356 so that further action, as required, can be taken.

[0120] When the downhole component 362 has been appropriately re-oriented, the driller then operates to mark the core as per normal practice.

[0121] 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.

[0122]
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.

[0123] It is also to be noted that while the lmdex Application does allow for both borehole and core orientation measurements to be attained during the run of the orientation measurement device as claimed, the description and claims make it clear that the inner tube must already be in place before the orientation measurement device is run down the drill string. This means that there still remains a separate secondary downhole process required to install the inner tube each time a core sample is required from the same borehole.

[0124] By contrast, the applicant's invention only requires the driller to focus on the assembly and connection of the invention to each inner tube. Furthermore, as both borehole and core orientation measurements are obtained through automated processes, the driller is not required to monitor timing devices to determine when the borehole or core orientation measurement should be taken.

[0125]
Furthermore, it is noted that the tool in the Imdex Application relies on elements located in the inner tube for core orientation measurements to be obtained.
If the inner tube is not present, or has not been properly prepared with the required elements, core orientation measurements can not be obtained. This is not the case in the present invention due to its unitary construction.

[0126] It should be appreciated by the person skilled in the art that the above invention is not limited to the embodiments described. In particular, the following modifications and improvements may be made without departing from the scope of the present invention:
= [0127] Other means of attaching the orientation measurement device to the inner tube 3 may be used other than a threaded end, provided that the method of attachment allows the position of the inner tube 3 to correspond with, or be calculated from, the position of the orientation measurement device 10.

However, given the context of the invention, having the orientation measurement device 10 contained in a housing 12 having a threaded end is preferable = [0128] The first measurement system 18 and second measurement system 20 may use other sensors than those described. For instance, the first measurement system 18 may employ tri-axial accelerometers in place or, or in conjunction with, the gyroscope 24. Similarly, the second measurement system 20 may omit the tri-axial magnetometers 28.
= [0129] The trigger sensing system 22 may incorporate different sensors as is relevant to the trigger events to be used to determine when to take the relevant measurements. For instance, the movement sensor 32 may be used to determine when the orientation measurement device 10 and inner tube 3 have been attached to the outer tube 2 and thus a borehole orientation measurement should be taken. Similarly, a connection sensor 34 may be used to determine when an overshot (not shown) has been connected to the orientation measurement device 10 prior to retrieval and use that event as a means to cease recording core orientation measurements.
= [0130] In a similar vein, a countdown timer may be used to determine the expiry of a predefined time period, the expiry fo the predefined time period acting as the desired trigger event.
= [0131] The storage memory 40 may be split so as to provide a first dedicated storage memory 40 for borehole orientation measurements and a second dedicated storage memory 40 for core orientation measurements.
= [0132] Preferably, the storage memory 40 has sufficient storage space so as to record a single borehole orientation measurement and a plurality of core orientation measurements equal to the expected duration that the orientation measurement device 10 will be stopped prior to a certain trigger event, such as breaking the core or the commencement of retrieval of the orientation measurement device 10.
= [0133] The processing system 36 may be dispensed with as an independent unit. In its place, the components of the processing system 36 may be incorporated into the first measurement system 18, second measurement system 20 and/or the trigger sensing system 22.

= [0134] The rotational disengagement means 46 may be omitted in its entirety. Alternatively, other forms of rotational disengagement means 46 may be employed to keep the inner tube 3 stationary while the outer tube 2 rotates.
= [0135] The topside communications device may be any processing device, such as a tablet, smartphone, notebook or desktop computer having an appropriate communications system through which a communication link may be established.
= [0136] While the gyroscope 24 must be operational at all times prior to recording the borehole orientation measurement, the sensors forming the second measurement system 20 may be powered only for the period in which they are required to provide measurements. In this manner, the size of, and/or draw on, the power unit may be minimised.
= [0137] The first measuring subsystem 312 may comprise of other measuring devices than the MEMS gyroscope 322 and accelerometers 324 as would be known by the person skilled in the art as applicable to measuring the orientation of a borehole.
= [0138] Similarly, the second measuring subsystem 314 may comprise of other measuring devices than the accelerometers 324 and temperature sensor 326 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).
= [0139] The first measuring subsystem 312 may calculate its azimuth value from appropriate Northing and Easting readings.
= [0140] The first measuring subsystem 312 and/or second measuring subsystem 314 may be used to measure other characteristics of the borehole or drilling operation, such as top dead centre of the borehole.
= [0141] In a preferred arrangement, to save power, processing means 328 may operate to shutdown MEMS gyroscope 322 following storage in storage means 330 of the borehole orientation measurements from the first measuring subsystem 312.
= [0142] Real-time clocks 336, 356 may be substituted for synchronised stop watches. Synchronisation, in this context, does not require the real-time clocks 336, 356 to be recording the exact same time, but have a sufficiently known time offset so as to allow the processing means 328, 348 to make adjustments as required to ensure correct correlation of core orientation measurements.
= [0143] The storage means 330 may be removable. However, as this means that the downhole component 362 cannot be a sealed unit, this is not preferable.
= [0144] The communication means 332, 352 may use any form of wireless communication technology or communications protocol, for instance, the communication means 332, 352 may communicate using infra-red signals.
Furthermore, the communication means 332, 352 need not communicate wirelessly, but this again means that the downhole component 362 cannot be a sealed unit.
= [0145] The handset 320 may be replaced with a general purpose device such as a smart phone, notebook computer or tablet. In such arrangements, the keypad 358 may be a virtual keypad. Thus, the handset 320 may be more appropriately be referred to as a surface communications device.
= [0146] The power means 334 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 362 may not be a sealed unit, induction charging arrangements are preferred.
= [0147] 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.
= [0148] 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 312, 314.
= [0149] The re-orientation process may incorporate visual cues, displayed to the driller by way of display unit 356 to facilitate re-orientation.
These visual cues may include an arrow or directional graphic to indicate the direction that the downhole component 362 must be rotated in order to achieve re-orientation or a flashing light the speed of which reflects how close the downhole component 362 is to being re-oriented.

= [0150] 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 362 must be rotated in order to achieve re-orientation.
= [0151] In a variation of the third embodiment, the real-time clocks 336, 356 need not be synchronised prior to operation of the downhole component 362. 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 362 re-establishes a communications channel with the handset 320. The processing means 328 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 336 to determine the time determined by the processing means 328 indicative of core break.
= [0152] The secondary measuring system 314 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.
= [0153] The reference core orientation measurement returned to the processing means 348 by processing means 328 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.
= [0154] Ideally, the driller maintains a period of drill silence in which at least two core orientation measurements may be taken by the accelerometers 324. 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 324.
= [0155] 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 312, 314. 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 312, 314 will be discarded (ie. not stored in storage means 330) or treated as not having been taken.
= [0156] In a variation on the fourth embodiment, a memory card may be used to record all measurement data. In this manner, the measurement data written to the storage means 330 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 400.
= [0157] In the third and fourth 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.
= [0158] In a variation of the third embodiment described, the processing means 328 does not operate to poll the components of the first measuring subsystem 312 for their current measurement values immediately on detection that the inner tube 1 is locked to the core barrel 7. Rather, the processing means 328 may operate to poll the components of the first measuring system 312 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.
= [0159] The processing means 328 may operate to poll the components of the first measuring subsystem 312 multiple times after detecting that the inner tube 1 is locked to the core barrel 7. The processing means 328 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.
= [0160] The processing means 328 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 362 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.
= [0161] The processing means 328 may also operate to wait a preset period of time before polling or querying the second measuring subsystem 314 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.
= [0162] It is to be appreciated by the person skilled in the art that the third and fourth embodiments 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 362 down the hole through normal gravitational forces and without the assistance of a wireline.
= [0163] While the invention has been described in the context of a threaded engagement between downhole componentry (such as downhole unit 362) and inner tube 2, other connecting methods can be used. These include other mechanical means of connection or non-mechanical means (such as magnetic connections).
[0164] It should be further appreciated by the person skilled in the art that the invention is not limited to the embodiments described above. Additions or modifications described in any embodiment, where not mutually exclusive, can be combined to form yet further embodiments that are considered to be within the scope of the present invention.
[0024]
Additionally, it should be noted that specific embodiments of the present invention have been described above in detail. However, 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.

Claims (26)

We Claim:

1. A method of obtaining borehole and core orientation measurements in a single run comprising the steps of:
lowering an orientation measurement device connected to an inner tube to a drilling position;
measuring the orientation measurement device's position in three-dimensional space at the drilling position;
commencing periodic measurement of the orientation of the inner tube by reference to a measurement of the roll angle orientation of the orientation measurement device; and determining the orientation of the inner tube just prior to a trigger event.

2. The method of claim 1, where the step of measuring the orientation measurement device's position in three-dimensional space at the drilling position occurs prior to the commencement of periodic measurement of the orientation of the inner tube.

3. The method of claim 1 or claim 2, the method further including the step of locking the orientation measurement device to the inner tube in a fixed rotational arrangement such that any rotation imparted to the inner tube is similarly impated to the orientation measurement device.

4. The method according to any preceding claim, where the step of commencing periodic measurement of the orientation of the inner tube occurs for a set number of measurements.

5. The method according to any preceding claim, further comprising the step of storing a set number of measurements of the orientation of the inner tube and once this storage capacity has been reached, the orientation measurement device either ceases taking measurements or starts writing over existing measurements on a historical basis.

6. The method according to any preceding claim, further comprising the step of ceasing periodic measurement of the orientation of the inner tube when the trigger event occurs.

7. The method according to any preceding claim, where the trigger event is one of the following: the exact time when the overshot is attached to the orientation measurement device; the expiry of a defined time period; the commencement of a sustained period of upward movement.

8. The method of any preceding claim, further comprising the step of rotationally disengaging the inner tube and/or orientation measurement device from the outer tube.

9. An orientation measurement device comprising:
a first measurement system; and a second measurement system;
where, on reaching a drilling position, the first measurement system measures the orientation measurement device's position in three dimensional space and the second measurement system commences periodic measurement of the orientation of the inner tube by reference to a measurement of the roll angle orientation fo the orientation measurement device.

10.An orientation measurement device according to claim 9, where the second measurement system does not commence periodic measurement of the orientation of the inner tube until after the first measurement system has measured the orientation measurement device's position in three dimensional space.

11.An orientation measurement device according to claim 9 or claim 10, further comprise rotational locking means, the rotational locking means operable to ensure that any rotation imparted to the inner tube is similarly imparted to the orientation measurement device.

12.An orientation measurement device according to claim 9 or claim 10, where the second measurement system further includes a fixed size memory for recording periodic measurements of the orientation of the inner tube.

13. An orientation measurement device according to claim 12, where measurements recorded in the fixed size memory are overwritten on a historical basis.

14. An orientation measurement device according to any one of claims 9 to 13, where the second measurement system further operates to determine the orientation of the inner tube prior to a trigger event.

15. An orientation measurement device according to any one of claims 9 to 14, where the second measurement system ceases periodic measurement of the orientation of the inner tube on detection of the trigger event.

16.An orientation measurement device according to any one of claims 9 to 15, further comprise rotational disengagement means, the rotational disengagement means operable to ensure that rotation of the outer tube occurs independently of the orientation measurement device and attached inner tube.

17.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.

18.A multi-purpose orientation measurement system according to claim 17, where the first measuring subsystem comprises a gyroscope and triaxial accelerometers for determining azimuth and dip measurements.

19.A multi-purpose orientation measurement system according to claim 17 or claim 18, 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.

20.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.

21. The method of claim 20, 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.

22.The method of claim 20 or claim 21, 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.

23. The method of any one of claims 20 to 22, 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.

24. The method of any one of claims 20 to 23, further including the step of shutting down the first measuring subsystem after storing measurements obtained therefrom.

25. The method of any one of claims 20 to 24, further including the steps of detecting a trigger event and, on detection of the trigger event, shutting down the second measuring subsystem.

26. The method of any one of claims 20 to 25, where the measurements taken by the first measuring subsystem include measurements from which azimuth and dip can be calculated.