WO2007137356A1

WO2007137356A1 - Core orientation system

Info

Publication number: WO2007137356A1
Application number: PCT/AU2007/000752
Authority: WO
Inventors: Andrew Beach; Gavin Mcleod
Original assignee: 2Ic Australia Pty Ltd
Priority date: 2006-05-29
Filing date: 2007-05-29
Publication date: 2007-12-06
Also published as: ZA200810448B; AU2007266335A1; AU2007266335B2; CA2653466A1

Abstract

A core orientation system (10) comprises an electronic orientation device (12) that connects to a back end (14) of a core tube (16), a core position indicator (CPI) 18 adapted for engagement with the core tube (16) when on the ground, and a remote control unit 22 that communicates between the device (12) and the CPI (18). The device (12) electronically logs orientation data of a reference point R on the core tube 16 relative to a first datum A at a time when a core sample (24) contained in the core tube (16) is in an insitu orientation. Once the core tube is retrieved and placed in a stable position the device (12) again logs orientation data of the reference point R to a second datum B. A rotational displacement ϑ from the first datum A to the second datum B is calculated and transferred to the CPI (18) which is then moved about the core tube (16). When the CPI (18) is moved to a position where it is rotated by ϑ from the second datum B, it emits a signal to indicate the position of the first datum A.

Description

CORE ORIENTATION SYSTEM

Field of the Invention

The present invention relates to a core orientation system for a core sample extracted from the ground.

Background of the Invention

Core sampling is used to allow geological surveying of the ground for various purposes including exploration and/or mine development. Analysis of the material within the core sample provides information on the composition of the ground. However in order to accurately interpret the information obtained from the core sample it is necessary to have knowledge of the orientation of the core sample relative to the ground from which it was extracted.

There are many known devices for orientating a core sample. Some of these devices are attached to a front end of a core tube and physically mark, or take an impression of a face of, the core sample. By relating the marking or impression to a known reference one is then able to determine the orientation of the core sample.

Other systems are known that electronically record information or data relating to the core orientation at the commencement or end of a core run rather than physically mark or take impressions of the core sample. One known system utilises an electronic orientation device that is screwed onto a back end of the core tube, a stopwatch, and a marking jig. A drill rig operator having attached the device to a core tube arms the device immediately prior to lowering the core tube through an associated drill string of a core drill and simultaneously commences a stop-watch. The device records readings of core orientation at fixed time intervals. On completion of drilling and prior to the breaking of the core, the stop-watch is stopped by the drill rig operator. The core tube is then retrieved from the ground and placed in a stable position. The time appearing on the stop-watch is then entered on the device. The device internally retrieves the related orientation data corresponding to that time. The entire core tube is then rotated on the jig until a visual indication is given by the device that the core is lying at an orientation with the underside of the core sample representing the bottom of the hole. A jig may then be used to assist a person in physically marking the core, for example with a pencil to denote the location of the bottom of the hole.

Summary of the Invention

According to one aspect of the present invention there is provided a core orientation system comprising: an electronic orientation device configured for connection with a core tube and which logs data relating to the orientation of a core sample extracted from the ground via the core tube,- a core position indicator configured for demountable engagement with the core tube,- a remote control unit that communicates with both the electronic orientation device and the core position indicator to transfer the data from the electronic orientation device to the core position indicator; and, a signalling system that emits a sensory signal when the core position indicator is moved about the core tube to a position which based on the data is indicative of the ground in situ orientation of the core.

In various embodiments the signalling system may be incorporated in either the remote control unit or in the core position indicator. The sensory signal may comprise any one or more of the group comprising: an auditory signal, a visible signal, a tactile signal.

The core position indicator may comprise a guide for guiding a marking implement for marking the core and/or the core tube or a component of the core tube. It is envisaged that the component of the core tube that may be marked is a core lifter case coupled to a front end of the core tube .

The guide may comprise a straight edge or a slot to facilitate the guiding of the marking implement to scribe or otherwise mark an indicia on or along a portion of the core and/or the core tube or a component thereof at a location indicative of the orientation of the core relative to the predetermined reference. Typically the predetermined reference corresponds with either the bottom or the top of a hole from which the core is extracted referenced to gravity.

The guide may further comprise a sensor to detect when the marker was moved along the guide and check that the guide was at the correct orientation at the time of marking. If the guide was not in the correct orientation the signalling system could indicate the error to the operator to enable them to correct the alignment or the angular displacement could be recorded and included in a downloadable data record for the geologist or core logging staff to enable them to correct the alignment.

The guide may in addition or alternatively comprise a recess or hole positioned to receive the marking implement at a location where the implement can be guided to contact a radial end face of the core sample .

The core position indicator may further comprise a mount that engages the core tube to couple the core position - A - indicator to the core tube in a manner allowing the core position indicator to rotate about the core tube. Further, the mount may further facilitate the sliding of the core position indicator axially of the core tube.

Both the core position indicator and the remote control unit may comprise a means of storing a downloadable data record of one or more data readings to provide a permanent record for auditing purposes.

According to a further aspect of the present invention there is provided a method of indicating the orientation of a core sample extracted from the ground comprising: electronically logging orientation data of a reference point on core tube relative to a first datum at a time when a core sample contained in the core tube is in its in situ orientation relative to the first datum; retrieving the core tube and placing the core tube in a stable position; electronically logging orientation data of the reference point on core tube relative to a second datum when the core sample is in the stable position determining a rotational displacement θ of first datum relative to the second datum mounting a core position indicator on the core tube; electronically transferring the displacement θ to the core position indicator; moving the core position indicator about the core tube ; and emitting a sensory signal when the core position indicator is rotated to a position displaced by θ from the second datum and thus pointing to or otherwise indicating the position of the first datum on the core sample.

The reference datum may comprise a bearing with reference to gravity. Brief Description of the Drawings

An embodiment of the present 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 a core orientation system in accordance with an embodiment of the present invention;

Figure 2 is an enlarged view of a portion of the system in Figure 1 in which an end of a core sample partially extends from an associated core tube; Figure 3 is an enlarged view of a portion of the system in Figure 1 in which an end of a core sample is disposed inside of the core tube;

Figure 4 is a schematic representation of a core sample orientated by an embodiment of the present invention; and, Figures 5 - 8 represent sequentially the steps in recording positional data of the core tube and core sample and transferring that data to the core sample.

Detailed Description of Preferred Embodiment

As illustrated in the accompanying drawings and in particular, in Figure 1, an embodiment of the core orientation system 10 in accordance with the present invention comprises an electronic orientation device 12 adapted for connection with a back end 14 of a core tube 16, a core position indicator (CPI) 18 adapted for demountable engagement with a front end 20 of the core tube 16, and a remote control unit 22 that communicates with both the electronic core orientation device 12 and the core position indicator 18. The system 10 further includes a signalling system (not separately shown) that emits a sensory signal. The signalling system may be incorporated in the CPI 18 although it may also reside within or be a part of the remote control unit 22. In yet a further variation both of the CPI 18 and the remote control unit 22 can include and/or function as signalling systems to emit the same or different sensory signals.

The electronic orientation device 12 logs orientation data of the core tube 16. Assuming there is either no, or a known or measurable, rotational slippage between the core tube 16 and the in situ core sample 24 orientation is the same as or related to the orientation of the core tube 16. Once drilling for the core 24 has ceased, and the core sample has been broken from the ground and retrieved to the surface with the core tube 16, the CPI 18 is demountably coupled to the front end 20 and the remote control unit 22 is operated to communicate with both the orientation device 12 and the CPI 18 to transfer data relating to the in situ orientation of the core sample 24 from the orientation device 12 to the CPI 18. The CPI 18 is then moved about the front end 20 to a position where it points to, is in alignment with, or otherwise indicates the orientation of the core 24 relative to a predetermined reference .

Looking at the system 10 in more detail, the electronic orientation device 12 may take the form of any known electronic orientation device used for downhole logging but which is further modified by the provision of a transceiver circuit to enable wireless communication between the device 12 and the remote control unit 22. Both the remote control unit 22 and the device 12 include internal timers that are synchronised when the unit 22 is used to initiate the device 12. Thus, prior to lowering the core tube 16 through a drill string an operator pushes an appropriate button on the remote control unit 22 which initiates or activates the orientation device 12 and simultaneously synchronises the timers in both devices. The orientation device may be pre-programmed, or programmable via the remote control unit 22, to take orientation readings at predetermined time intervals. For example orientation readings may be taken every 1, 2 or 5 seconds. In a further embodiment multiple successive readings may be taken over a small time interval or pulse and repeated over a longer duty cycle.

The orientation device 12 takes readings or measurements of orientation as the core tube 12 descends through the core drill and is latched into place near a downhole end of the core drill. The core drill is operated to cut a core sample 24 from the ground. Once the drill rig operator has ceased drilling and just before or after lifting of the drill string to effect a core break the operator pushes a "take reading" button 26 on the remote control unit 22. The control unit 22 records the time elapsed since the device 12 was initiated. In one variation, the device 12 may take multiple readings (eg say 3 readings) over a predetermined recording period, for example 30 seconds. During this period the unit 22 may be programmed to display a message such as "please wait" and/or diplay a count down of the recording period. This provides time for stabilisation of the core drill and core tube 12 and also provides a degree of error checking in that if the three readings are shown as being disparate by more than a allowable tolerance then it may be deduced that the reading is faulty and should be disregarded.

More particularly, in terms of error checking the data logged by the orientation device 12 may be analysed, either by the device 12 itself while in the hole, or by the remote control unit 22, or indeed by a separate device, using statistical measures of its accuracy. The logged data may be analysed to identify the presence of any movement during the logging of orientation data. This may include linear and/or rotational direction of motion, which is itself logged and provided to a user. These self checks may be beneficial to identify service requirements. In particular the indication of movement during logging may be beneficial in identifying improper operation of the orientation device and thus flag the need for training or retraining of operators. For example multiple logged orientation data on either side, in a time line sense, of a specific individual or averaged data point used as the orientation data at the time of core break, can be analysed to ascertain whether there was any appreciable motion (ie change in logged orientation) immediately before or after the core break when the core orientation data was being logged. Thus data in a time period adjacent of a core break (and in particular before the core break) can be analysed to detect linear/rotational motion of the core tube 12. If this motion is outside of an acceptable range the system 10 can log that information and the signaling system can emit a sensory signal to alert a user of that variation.

The operator can be signalled of the expiration of the recording period by the unit 22 displaying a message such as "reading complete retrieve core tube" and/or an auditory message.

The drill operator may then retrieve, the core tube 16 with the orientation device 12 in a conventional manner and place the core tube in a stable position such as on a core rack or other surface.

At this time the CPI 18 is coupled to the front end 20 of the core tube 16. To this end the CPI 18 is provided with a mount 30 in the form of a spring clip 30 that snaps on to the tube 16. The mount 30 enables the CPI 18 to be rotated or turned relative to the core tube 16, about a longitudinal axis of the tube 16 as well as being able to slide axially relative the tube 16. - S -

The CPI 18 includes an electronics module 32 which contains transceiver circuits to enable wireless communication with the remote control unit 22; and electronic orientation circuit which senses the orientation of the CPI 18 relative to a known reference (typically gravity) . It is further envisaged that the electronics module 32 would include the signalling system.

The CPI 18 further comprises a guide 34 for guiding a marking implement such as a pencil, pen or scribing instrument for marking the core 24 or the core tube 16, or a component thereof such as a core lifter case 36 that is screwed to the front end 20 of the core tube 16. The guide 34 is in the form of a thin straight slat 37 that extends in a direction of the axis of the core tube 16 and is provided with an elongate slot 38. A forward most end of the slat 37 is also provided with a guide block 40 provided with an axially extending hole 42. The CPI 18 is coupled to the tube 16 in a position so that the block 40 overhangs a front end of the core lifter case 36 and more particularly, as shown in Figure 2, is in a location in front of a face 44 of core sample 24 contained within the core tube 16.

Figures 5 - 8 depict the process in logging orientation data of the core sample 24, transferring that data to the CPI 18, and subsequently moving the CPI 18 relative to the core tube 16 to a location where the CPI 18 points to or otherwise indicates or signifies the ground in situ location of the core sample 24.

Figure 5 represents the initial state of the system 10 prior to lowering the core tube 16 into a bore hole through a drill string (not shown) . The orientation device 12 is turned ON and an internal timer within the orientation device 12 is synchronised with an internal timer of the remote control unit 22. This is achieved by- wireless communication between the remote control unit 22 and a transceiver within the orientation device 12.

As mentioned above, while the core tube 12 descends through the drill string and bore hole the orientation device 12 regularly logs data relating to the position of the core tube 12. Moreover, the logging of data provides positional information of the location of a reference point R relative to a predetermined first reference datum. The reference point R is an arbitrary but fixed reference point designated by the orientation device 12. It is possible but not necessary for the reference point R to have a corresponding physical marking on the exterior of the device 12. In this embodiment the first reference datum is a zero bearing relative to the direction of gravity or a "gravity vector" , marked as A in Figures 6 - 8.

Just prior to or after breaking of the core sample 24 from the in situ ground, an operator presses the "take reading" button 26 on the remote control unit 22. This activates the timer within the control unit 22 to log the period of time between initiation of the orientation device 12, and the time just before or after core break. This time maybe displayed on a display 28, and in this example is shown as 57 minutes. The core tube 16 with its core 24, is retrieved from the drill string and bore hole and placed in a stable position such as on a core or rod rack. An operator now presses a "sync reading" button 46 on the remote control unit 22. This causes the remote control unit 22 to interrogate the orientation device 12 and retrieve the orientation data of the core tube 16 and core 24 at the time corresponding to when the "take reading" button 26 was pressed. In the example shown in Figure 6, the orientation of the reference point R from the reference datum A 57 minutes after the initiation of the orientation device 12 is shown as α. That is at the time just before or after the core break the reference point R was at a bearing of α from the "gravity vector" A..

The reference point A represents the lower most point in the bore hole from which the core sample 24 is extracted and thus corresponds with the lowest point or line of the core sample 24 when in situ in the ground. When the core tube 16 is retrieved and placed on the core rack, it is possible, although unlikely, that point A will correspond with the position of the gravity vector B at ground level (i.e. a zero bearing with reference to the direction of gravity) , which can be considered to be a fresh or second reference datum. Thus, the remote control unit 22 is operated to interrogate the orientation device 12 to obtain a fresh or second reading of the displacement or bearing β of the reference point R from the second datum being the current "gravity vector" position B. The unit 22 can now calculate the displacement of the downhole gravity vector position A to the current gravity vector position B as θ=β-α .Once the remote control unit 22 has obtained the angle θ from the device 12, the control unit 22 transfers this data to the CPI 18. For example if α is measured as 129° , and β as 205 then the angle θ in this example will be 76° and displayed on the display 28 of the remote control unit 22. It should be understood however that there is no requirement for this displacement to be shown on the display 28.

As shown in Figure 8, the CPI 18 is now mounted on the core tube 16 and juxtaposed so that the guide block 40 overhangs the core lifter case 36 and is in front of the face 44 of the core 24. Most conveniently, but not essentially, the CPI 18 is mounted on the core tube 16 at a location about 180° form the gravity vector reference location B. In any event as previously described the CPI 18 has an electronic circuit to sense its own bearing relative to the gravity vector bearing. The unit 22 transfers the angle θ to the CPI 18. The unit 22 may optionally also receive the instantaneous bearing of the CPI 18. The CPI knowing both θ and its own orientation, both referenced to gravity vector B, can calculate the rotational displacement required to reach the downhole gravity vector position A. Assuming the CPI 18 is initially placed exactly 180 from B, then in the current example the CPI (and indeed the unit 22) can calculate that the CPI requires a rotation of 104° in the clockwise direction to reach point A. If the unit 22 is operated to interrogate the CPI 18 as the CPI 18 is being rotated about the core tube, the unit 22 can also display or otherwise provide information as to the required rotation (i.e. in terms of degrees and direction) for the CPI 18 to reach the position A. For example the display 28 can display a message such as "rotate right" or "rotate left" or "stop" when the position A is reached. Further either one or both of the CPI 18 and unit 22 can provide graded sensory signals that vary as the CPI 18 gets closer to or further from the position A. The sensory signals may include for example visual signals such as the turning ON of a light or the flashing of a light on one or both of the CPI 18 and the control unit 22; emission of an auditory signal by one or both of the CPI 18 and the remote control unit 22; the display of a visual readable message on the remote control unit 22 or the emission of a tactile signal such as a vibration from the remote control unit 22.

The initial mounting of the CPI 18 on the core tube 16 is depicted by the phantom line in Figure 8 while the position of the CPI 18 when rotated to position B is shown in the solid line

CPI 18, now points to or otherwise indicates the location of the reference datum A which corresponds with the lower most point of a core tube 16 and thus the core 24 at the time of the core break. This then characterises the location of the core sample 24. A user can mark one or both of the core 24 and core lifter case 36 by running a marker along the slot 38 to produce a "bottom of the hole line" 48 on the core sample 24. In the event that the core sample 24 is jammed in the core lifter case 36 as shown in Figure 4, the line 48 is initially marked along a core lifter case 36. The core lifter case 36 can then be unscrewed from the remainder of the core tube. As the core lifter case 36 is rotated the core sample 24 rotates with it thereby maintaining its rotational position relative to the core lifter case 36. The line 48 can then be extended on the core sample 24 once it is removed from the core tube 16. The face 44 of the core sample 24 can also be marked with a marker to produce a dot 50 (shown in Figure 4) by passing the marker through the hole 42 formed in the guide block 40. Dot 50 again represents the location of the bottom or lowest point in the hole from which the core sample 24 was extracted.

The CPI 18 may further comprise a sensor to detect when the marker was moved along the guide 34 and/or inserted in the hole 42 and check that the CPI 18 was at the correct orientation at the time of marking. This can be effected for example by way of bobbin slidably retained in the slot 38 and into which a marker in inserted to mark the underlying core tube 16 and core sample 24, with say a magnetic sensor mounted in the slat 37 to detect motion of the bobbin; or for the hole 42 by say an optical sensor that can detect the insertion of a marker in the hole 42. The CPI 18 can be programmed or otherwise configured to detect when such motion occurs. Indeed the CPI 18 may be further programmed to automatically send its orientation to the remote control unit 22 whenever the marking process is sensed. If the CPI 18 was not in the correct orientation (i.e. pointing to the datum A) at that time the signalling system (whether embedded in the CPI 18 or in the remote control unit 22) will indicate an error to the operator to enable them to correct the alignment or the angular displacement from the correct could be recorded and included in a downloadable data record for the geologist or core logging staff to enable them to correct the alignment.

It is further envisaged that various embodiments of the orientation device 12 may perform other self checks and provide users with status information/messages. Status messages may include one or a combination of: low battery power, communications error, system faults.

Either one or both of the CPI 18 and the remote control unit 22 may also be configured to store and allow downloading of records of one or more data readings to provide a permanent record for auditing purposes. This can easily facilitated by incorporation of an electronic memory or allocation of an area of existing electronic memory in the CPI 18 and remote control unit 22, with download being via the existing communications system that operates between the CPI 18 and remote control unit or via a hardware connection such as a USB jack.

Modifications and variations in the above described embodiments that would be obvious to a person of ordinary skill in the art are deemed to be within the scope of the present invention the nature of which is to be determined from the above description.

Claims

Claims :

1. A core orientation system comprising: an electronic orientation device configured for connection with a core tube and which logs data relating to the orientation of a core sample extracted from the ground via the core tube; a core position indicator configured for demountable engagement with the core tube; a remote control unit that communicates with both the electronic orientation device and the core position indicator to transfer the data from the electronic orientation device to the core position indicator; and, a signalling system that emits a sensory signal when the core position indicator is moved about the core tube to a position which based on the data is indicative of the ground in situ orientation of the core.

2. The core orientation system according to claim 1 wherein the signalling system is incorporated in any one or both of the remote control unit or in the core position indicator.

3. The core orientation system according to claim 1 or 2 wherein the sensory signal comprises any one or more of the group comprising: an auditory signal, a visible signal, a tactile signal.

4. The core orientation system according to any one of claims 1 - 3 wherein the core position indicator comprises a guide for guiding a marking implement for marking the core and/or the core tube or a component of the core tube.

5. The core orientation system according to claim 4 wherein the component comprises a core lifter case coupled to a front end of the core tube.

6. The core orientation system according to claim 4 or 5 wherein the guide comprises a straight edge or a slot to facilitate the guiding of the marking implement to scribe or otherwise mark an indicia on or along a portion of the core and/or the core tube or a component thereof at a location indicative of the orientation of the core relative to the predetermined reference.

7. The core orientation system according to claim 6 wherein the predetermined reference corresponds with either the bottom or the top of a hole from which the core is extracted referenced to gravity.

8. The core orientation system according to any one of claims 4 - 7 wherein the guide comprises a recess or hole positioned to receive the marking implement at a location where the implement can be guided to contact a radial end face of the core sample .

9. The core orientation system according to any one of claims 1 - 8 wherein the core position system indicator comprises a mount that engages the core tube to couple the core position indicator to the core tube in a manner allowing the core position indicator to rotate about the core tube.

10. The core orientation system according to claim 9 wherein the mount further facilitates the sliding of the core position indicator axially of the core tube.

11. The core orientation system according to any one of claims 1 - 10 wherein the remote control unit and the electronic orientation device each comprise a respective timer and wherein the remote control unit is operable to synchronise the timers.

12. The core orientation system according to claim 11 wherein the electronic orientation device logs orientation data at time intervals measured by its timer.

13. The core orientation system according to claim 11 or 12 wherein the remote control unit is operated to record a period of time between synchronisation of the timers and a time just before or after lifting of a drill in which the core tube is disposed to effect a core break detaching the core sample from the ground.

14. The core orientation system according to any one of claims 1 - 13 wherein the core position indicator comprises an electronic orientation circuit for sensing rotational orientation of the core position indicator relative to a known second reference datum.

15. The core orientation system according to any one of claims 1-14 wherein one or both of the core position indicator and the remote control unit comprise a memory for storing a downloadable record of the data.

16. The core orientation system according to any one of claims 4-15 wherein the guide further comprises a sensor to detect when the marking implement is used to mark the core and/or the core tube or a component of the core tube and wherein the core position system performs a test to check that the guide was at the correct orientation at the time of marking.

17. The core orientation system according to claim 16 wherein signalling system emits a sensory signal in the event that the guide was not in the correct orientation at the time of marking.

18. The core orientation system according to claim 17 wherein, in the event that the guide was not in the correct orientation at the time of marking the core position system records an angular displacement from the correct orientation.

19. The core orientation system according to any one of claims 1 - 18 wherein the core orientation system is configured to analyse multiple data logged in a period of time in the vicinity of a time at which a core break action is preformed to detect and/or record variations in motion of the core tube in the period of time.

20. The core orientation system according to claim 19 wherein the signalling system emits a sensory signal in the event that the variation in motion is outside of a predetermined range of motion.

21. A method of indicating the orientation of a core sample extracted from the ground comprising: electronically logging orientation data of a reference point on core tube relative to a first datum at a time when a core sample contained in the core tube is in its in situ orientation relative to the first datum; retrieving the core tube and placing the core tube in a stable position; electronically logging orientation data of the reference point on core tube relative to a second datum when the core sample is in the stable position determining a rotational displacement θ of first datum relative to the second datum mounting a core position indicator on the core tube; electronically transferring the displacement θ to the core position indicator; moving the core position indicator about the core tube ; and emitting a sensory signal when the core position indicator is rotated to a position displaced by θ from the second datum and thus pointing to or otherwise indicating the position of the first datum on the core sample.