AU2015101718A4 - Multifunction orientation system with failover measurement system - Google Patents

Abstract

-23 A multifunction orientation system 10, 100 having a primary measuring means and at least one secondary measuring means. The primary measuring means (36) measures a first drilling characteristic from which an orientation measurement can be determined. The at least one secondary measuring means (38, 40) measures a second drilling characteristic from which an orientation measurement can be determined. When the multifunction orientation system 10, 100 determines that the current measurements of the primary measuring means (36) are anomalous, the at least one secondary measuring means (38, 40) operates to take measurements, the system 10, 100 operable to communicate the orientation measurement determined from the measurements recorded by the at least one secondary measuring means (38, 40) to the user as the proper orientation measurement. a il

Description

-1 "MULTIFUNCTION ORIENTATION SYSTEM WITH FAILOVER MEASUREMENT SYSTEM" FIELD OF THE INVENTION [0001]The invention relates to a multifunction orientation system with failover measurement system. The multifunction orientation system operates to correlate or rely on azimuth, inclination and roll angle orientation measurements provided by the failover measurement system in anomalous environments, such as highly magnetic environments. 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] Orientation surveys are an important part of modern mining operations. Such surveys can provide an indication of the direction in which a borehole in progressing, while others can be used to determine the specific alignment of ore bodies or geotechnical fractures. [0004] However, the sensors used to measure these factors can be prone to error in certain environments. For instance, readings obtained from magnetometers become unreliable in highly magnetic environments. Similarly, areas of high environmental noise or temperature can render unreliable readings taken from accelerometers. [0005]The present invention therefore seeks to provide a multifunction orientation system that allows more reliable orientation measurements to be captured through an alternative measurement system when operating in an environment that potentially renders measurements taken through a primary measurement system unreliable. SUMMARY OF THE INVENTION [0006] 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".

-2 [0007] In accordance with a first aspect of the present invention there is a multifunction orientation system comprising: a primary measuring means for measuring a first drilling characteristic from which an orientation measurement can be determined; at least one secondary measuring means for measuring a second drilling characteristic from which an orientation measurement can be determined; and where when the multifunction orientation system determines that the current measurements of the primary measuring means are anomalous, the at least one secondary measuring means operates to take measurements, the system thereafter operable communicate the orientation measurement determined from the measurements recorded by the at least one secondary measuring means as the proper orientation measurement. [0008]The primary measuring means may be a gyroscope and the at least one secondary measuring means includes at least one of the following: tri-axial accelerometers; tri-axial magnetometers, or, alternatively, the primary measuring means may be a tri-axial accelerometer and the at least one secondary measuring means includes at least one of the following: tri-axial magnetometers; gyroscope, or, as a further alternative, the primary measuring means may be a tri-axial magnetometer and the at least one secondary measuring means includes at least one of the following: tri-axial accelerometers; gyroscope. [0009]The multifunction orientation system may include at least one additional measurement sensor, the at least one measurement sensor operable to measure at least one characteristic that can bias the measurements taken by the primary measuring means, the multifunction orientation system operable to determine whether measurements of the primary measuring means are anomalous based on correlated measurements taken by the at least one additional measurement sensor. [0010]The multifunction orientation system may incorporate a core barrel adaptor, the orientation measurement to be determined by the primary and secondary measuring means and communicated to the user being the orientation of the core barrel adaptor.

-3 [0011] In accordance with a second aspect of the present invention there is a method of determining the orientation of a device comprising the steps of: measuring a first drilling characteristic from which an orientation measurement can be determined; measuring at least one second drilling characteristic from which an orientation measurement can be determined; determining whether the measurements of the first drilling characteristic are anomalous and, if so determined, communicating to the user the orientation measurement determined from the measurements of the at least one second drilling characteristic as the proper orientation of the device. BRIEF DESCRIPTION OF THE DRAWINGS [0012] 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 a first embodiment of the present invention. Figure 2 is a schematic representation of a second embodiment of the present invention. Figure 3 is a schematic representation of a third embodiment of the present invention. PREFERRED EMBODIMENTS OF THE INVENTION [0013]Specific embodiments of the present invention are now described in detail. The terminology used herein is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the present invention. [0014] In accordance with a first embodiment of the invention there is a multifunction orientation system 10 with fallover measurement system. The multifunction orientation system 10 comprises: * a downhole unit 12; and * a handheld unit 14. [0015]The downhole unit 12 comprises a housing 16, a measurement unit 18, a processing unit 20, storage means 22, a communications unit 24 and a battery 26.

-4 [0016]The housing 16 is cylindrical in shape. As the housing 16 is intended to form part of an inner tube 28 of a drill string 30, the dimensions of the housing 16 are dictated to a large extent by the type of drill string 30 with which the multifunction orientation system 10 is intended to be used. As this would be readily understood by the person skilled in the art, the dimensions of the housing will not be discussed further here except where relevant to the invention. [0017]In this embodiment, the housing 16 has a first end 32 and a second end 34. The first end 32 has a male threaded portion. Second end 34 has a recessed female threaded portion. [0018]In this configuration, the first end 32 is adapted to be received within a recessed open female threaded end of the inner tube 28. The second end 34 is adapted to receive a male threaded end of a spacer tube (not shown). [0019] As the housing 16 is intended to protect the electronic components that form the measurement unit 18, processing unit 20, storage means 22, communications unit 24 and battery 26, the housing also contains a plurality of cushioning layers (not shown). These cushioning layers increase in the robustness of their cushioning as they close in on the electronic components. [0020]The measurement unit 18 consists of a vibrating structure gyroscope incorporating microelectromechanical systems technology 36 (more commonly referred to as a "MEMS gyroscope", a term which will be used throughout the remainder of this specification), tri-axial accelerometers 38 and tri-axial magnetometers 40. The tri-axial magnetometers 40 are spaced from the other electronic components to ensure that it is not subject to magnetic interference created during the operation of such components. [0021]The measurement unit 18 further consists of at least one additional measurement sensor 41. In this embodiment the at least one additional measurement sensor 41 is a temperature sensor. [0022]The processing unit 20 comprises a low-power processor 42, read-only memory 44 and transitional memory 46. The processing unit 20 is in data and control communication with each of the MEMS gyroscope 36, tri-axial accelerometers 38 and tri-axial magnetometers 40. The processing unit 20 is also in data and control communication with the storage means 22 and communications unit 24.

-5 [0023]The actual role of the processing unit 20 will be described in more detail below. [0024]The storage means 20 takes the form of flash memory. The capacity of the flash memory may vary according to user requirements, but in this embodiment the flash memory has a capacity of four gigabytes. [0025]The storage means 20 also includes components to facilitate the reading of data from, and the writing of data to, the flash memory. As such components are standard elements of most storage means 20 they will not be described further here and expected to be within the purview of the person skilled in the art. [0026]The communications unit 24 takes the form of a radio frequency ("RF") transceiver. The RF transceiver is attuned to communicate with a like RF transceiver 48 contained within the handheld unit 14. [0027]The battery pack 26 takes the form of a collection of lithium batteries configured and housed using an arrangement as described in Australian Provisional Patent Application 2011900212 titled "Modular Battery Pack" also filed by the applicant, which is hereby incorporated by reference. The battery pack 26 provides power to the various elements of the downhole unit 12. [0028] In addition to the radio frequency transceiver 48 described above, the handheld unit 14 includes a user interface 50, battery 52 and ancillary processing unit 54. [0029]The user interface 50 comprises a display 56 and membrane keypad 58. The role of the user interface 50 will be described in more detail below. [0030]The battery 52 is a standard user-replaceable lithium battery that provides power to the various elements of the handheld unit 14. [0031]The ancillary processing unit 54 comprises a low-power processor 60, read only memory 62 and transitional memory 64. The ancillary processing unit 54 is in data and control communication with each of the display 56, membrane keypad 58 and radio frequency transceiver 48. [0032]This first embodiment of the invention will now be described in the context of its intended use.

-6 [0033]The handheld unit 14 and a pair of downhole units 12 are delivered to the drilling site. Following delivery, the handheld unit 14 and the downhole units 12 are powered up. [0034] Powering up of the downhole unit 12 causes the low-power processor 42 to commence execution of a computer program stored in read-only memory 44 and using the storage space of transitional memory 46 as and when required. Similarly, powering up of the handheld unit 14 causes the low-power processor 60 to commence execution of a computer program stored in read-only memory 62 and using the storage space of transitional memory 64 as and when required. [0035] Rather than continue to refer back to the operation of the low-power processors 42, 60, etc., for the remainder of this embodiment, descriptions of further functions of both the downhole unit 12 and the handset unit 14 should be read as the execution of software by way of the appropriate processor et. al. to achieve those functions. [0036]As part of the initial instructions executed by the low power processor 42, the RF transceiver 24 is commanded to search for handheld units 12 within communications range. When the RF transceiver 24 identifies a handheld unit 12 within communications range, the RF transceiver 24 of the downhole unit 12 and the RF transceiver 48 of the handheld unit 14 establish a communications channel for future data and control communication between the two units 12, 14. [0037]In this case, as there are two downhole units 12, the handheld unit 14 establishes separate communications channels with both units 12. [0038]With a communication channel between the handheld unit 14 and downhole unit 12 established, the handheld unit 14 issues commands to the downhole unit 12 to perform a series of self tests. As the self tests are not important to the invention, they will not be described in more detail here. [0039] Upon successful completion of the self tests, the downhole unit 12 sends a command signal to the handheld unit 14 to this effect. [0040]Following receipt of this command signal, the handheld unit 14 reports to a user that the downhole unit 12 is ready for operation by way of an appropriate message conveyed via display 56.

-7 [0041]The user is then able to use the handheld unit 14 to set the use parameters for the multifunction orientation system 10. [0042]To do this, the user presses the button of the membrane keypad 58 marked "New Survey". Pressing this button causes the low-power processor 60 to execute a series of commands that operate to request from the user the depth at which the desired measurement is to be taken. [0043] In this embodiment, the user uses the numeric buttons of the membrane keypad 58 to enter in the desired depth value. Following entry of this value, the user can then initiate the desired survey by pressing the "Commence Survey" button of the membrane keypad 58. [0044] Pressing the "Commence Survey" button causes the low-power processor 58 to issue: * a data signal to the downhole unit 12 via the established communication channel representative of the depth at which the desired measurement is to be taken (hereafter "the desired depth value"); AND * a command signal to the downhole unit 12 via the established communication channel. [0045] Receipt of this command signal by the downhole unit 12 causes the low-power processor 42 to issue a command to the MEMS gyroscope 36 to start its measurements. At the same time, the user commences their normal drilling procedure. As drilling progresses, at some point the communications channel between the downhole unit 12 incorporated into the drill string 30 and the handheld unit 14 is broken. [0046]As drilling continues, the MEMS gyroscope 36 continues to operate, taking measurements at pre-determined sample rates. [0047]While these measurements are initially recorded as analogue signals, the MEMS gyroscope 36 operates to convert the analogue signals into digital values. The digital values are then conveyed back to the low-power processor 42. [0048]The low-power processor 42 processes the digital values it receives from the MEMS gyroscope 36 to determine a depth measurement.

-8 [0049]The determined depth measurement is then compared against the desired depth value. If the determined depth measurement is less than the desired depth value, the low-power processor 42 repeats this processing loop until the determined depth value is equal to or exceeds the desired depth value. [0050]While this processing loop continues its execution, the user maintains drilling progress according to their drilling plan. [0051]As the pace of drilling generally resides in the range of centimetres per minute, and the sample rate of known slow MEMS gyroscopes 36 are calculated in seconds, even if the determined depth value exceeds the desired depth value, the difference in depth is likely to be minimal. In this manner, the survey will remain practically accurate even if not technically accurate. [0052] When the low-power processor 42 determines a depth value that is equal to or exceeds the desired depth value, the low power processor 42 operates to issue separate commands to the tri-axial accelerometers 38 and tri-axial magnetometers 40 to start their respective measurements. A command is similarly issued by the low power processor 42 to the additional measurement sensor 41 to commence measurement. [0053] Following receipt of its initiation command, the tri-axial accelerometers 38 operate to measure the effect of gravity on each of its orthogonal sensors. The tri axial accelerometers 38 also seek to obtain the then current temperature measurement as recorded by the additional measurement sensor 41. On receipt of the then current temperature measurement from the additional measurement sensor 41, the tri-axial accelerometers operate to adjust the orientation measurement as determined by its raw measurement values to compensate for temperature variations. This compensated value is then conveyed back to the low-power processor 42. [0054] In a similar manner, following receipt of its initiation command, the tri-axial magnetometers measure the strength of the magnetic field present at the current depth at each of its orthogonal sensors. This magnetic field measurement value is then conveyed back to the low-power processor 42.

-9 [0055]A further orientation value is also determined by the MEMS gyroscope 36 and conveyed back to the low-power processor 42. [0056]The additional measurement sensor 41 also operates to convey its measurements to the low-power processor 42. [0057]On receipt of the various measurement values from each of the MEMS gyroscope 36, tri-axial accelerometers 38, tri-axial magnetometers 40 and additional measurement sensor 41, the low-power processor 42 combines these values into a data record 66 along with the determined depth value. This data record 66 is then written to flash memory 20 for permanent storage. [0058]As the user knows the depth of the downhole unit by way of the process described above, when the user knows they have reached the desired depth they stop drilling and hold the drill string 30 stationary for a period of one minute. This allows the various components of the measurement unit 18 to take their measurements without interference caused by drilling, such as vibration. Furthermore, by keeping the drill string 30 stationary at the desired depth, the repetitive loop executed by the low-power processor 42 will ensure that multiple measurement readings are obtained at the desired depth. [0059]Once the one minute stationary period has expired, the user can retrieve the drill string 30 and with it, the downhole unit 12. [0060]When the drill string 30 has been retrieved to the surface, the user retrieves the handheld unit 14 and presses the "Retrieve Measurement" button of the membrane keypad 58. Pressing this button issues a command to the RF transceiver 24 to search for the handheld unit 12 with which it had established the previous communications channel. When the RF transceiver 24 identifies this handheld unit 12, the RF transceiver 24 of the downhole unit 12 and the RF transceiver 48 of the handheld unit 14 re-establish this communications channel. [0061]With the communications channel re-established the handheld unit 14 sends a command to the downhole unit 12 to forward on the stored measurement value for the desired depth. In response to this command, the handheld unit 14 communicates the first data record 66 stored in flash memory 22.

-10 [0062]On receipt of the data record 66 the handheld unit 14 operates to process the values of the data record 66 to determine whether the measurements taken from the tri-axial accelerometers 38, tri-axial magnetometers 40 or additional measurement sensor 41 are suggestive of an anomalous environment that calls into question the measurements taken by the MEMs gyroscope 36. [0063] If an anomalous environment is not considered to be present for any reading, the handheld unit 14 processes the measurements of the MEMS gyroscope 36 to form an orientation measurement that can be used for suitable display via the display 56. The orientation measurement is then so displayed. [0064] If an anomalous environment is considered to be present, then the handheld unit 14 operates to process the measurements of either the tri-axial accelerometers 38, or the tri-axial magnetometer 40, for the relevant period where the gyroscopes measurements are considered potentially unreliable to result in an alternative orientation measurement (or set of alternative orientation measurements). The alternative orientation measurement (or set of alternative orientation measurements) are then used to determine an orientation measurement that can be used for suitable display via the display 56. The orientation measurement is then so displayed. [0065] It should be noted that once one downhole unit 12 has been retrieved to the surface, it is possible to commence operation of the second paired downhole unit 12 using the same process as described above, before seeking to retrieve the measurement values from the retrieved downhole unit 12. This then allows drilling to proceed on an almost continuous basis. [0066] In accordance with a second embodiment of the invention, where like numerals reference like parts, there is a multifunction orientation system 100 with failover measurement system. The system 100 contains all of the hardware components of the system 10 of the first embodiment, but as adapted to perform core orientation. [0067] In order to achieve this change in function, the system 100 further includes a spacer tube 102 and a core barrel adaptor 104.

-11 [0068]The spacer tube 102 has a male threaded end and a recessed female threaded end. The male threaded end is adapted to be securely connected to the recessed female threaded portion of second end 34. [0069]The length of the spacer tube 102 should be such that the length of the connected spacer tube 102 and downhole unit 12 matches the standard length of each segment of inner tube 28. [0070]The core barrel adaptor 104 has a male threaded portion adapted to be received within the recessed female threaded end of the spacer tube 102. The form and shape of the core barrel adaptor 104 is otherwise dictated by the inner tube 28 and core barrel (not shown) used. Such forms and shapes would be readily known, or readily apparent, to the person skilled in the art and therefore will not be discussed further here. [0071] It should be noted that the arrangement of the downhole unit 12 relative to the inner tube 28 is such that the inner tube 28 is free to rotate as per normal operation of the drill string 30. However, such rotation must be restricted, if not prevented, from being imparted to the downhole unit 12. Furthermore, the downhole unit 12 must maintain a fixed rotational relationship at all times with the core barrel (not shown). To do otherwise will mean that the rotational orientation measurements taken by the downhole unit 12 will not be representative of the rotational orientation of the core barrel. [0072]This second embodiment of the invention will now be described in the context of its intended use, however, as its intended use is almost identical to that of the first embodiment, it is only those elements of divergence that will be described in more detail below. [0073]Once the handheld unit 14 has been set up for use, the user manipulates the handheld unit 14 to set the use parameters for the multifunction orientation system 100. [0074]To do this, the user presses the button of the membrane keypad 58 marked "New Core Orientation". Pressing this button causes the low-power processor 60 to execute a series of commands that operate to request from the user the depth at which the core orientation measurement is to be taken.

-12 [0075] In this embodiment, the user uses the numeric buttons of the membrane keypad 58 to enter in the desired depth value. Following entry of this value, the user can then initiate the desired survey by pressing the "Commence Core Orientation" button of the membrane keypad 58. [0076] Pressing the "Commence Core Orientation" button causes the low-power processor 58 to issue: * a data signal to the downhole unit 12 via the established communication channel representative of the depth at which the core orientation measurement is to be taken (hereafter "the desired depth value"); AND * a command signal to the downhole unit 12 via the established communication channel. [0077] Receipt of this command signal by the downhole unit 12 causes the low-power processor 42 to issue a command to the MEMS gyroscope 36 to start its measurements. [0078]At the same time, the user then connects the core barrel adaptor 104 to the core barrel. The core barrel adaptor 104 is then connected to the spacer tube 102 which is ultimately connected to the downhole unit 12. The user then check the connections between the downhole unit 12, core barrel adaptor 104 and inner tube 28 to ensure that there is no movement between these components other than allowed movement as described above. [0079]The user then commences their normal drilling procedure. In this arrangement, however, measurements begin to be collected from the various sensors as described above from commencement of drilling. These measurements are taken at periodic intervals and stored in flash memory 22 until retrieval of the downhole unit 12 commences. [0080]As the user knows the depth of the downhole unit by way of the process described above, when the user knows they have reached the desired depth they stop drilling and hold the drill string 30 stationary for a period of one minute. This allows the various components of the measurement unit 18 to take their measurements without interference caused by drilling, such as vibration. Furthermore, by keeping the drill string 30 stationary at the desired depth, the -13 periodic measurement loop executed by the low-power processor 42 will ensure that multiple measurement readings are obtained at the desired depth. [0081] Once the one minute stationary period has expired, the user can retrieve the drill string 30 and with it, the downhole unit 12. [0082] In this embodiment, as discussed above, as soon as the user commences retrieval of the drill string 30 the various components of the measurement unit 18 are commanded to shut down their measuring activities and/or cease storing these measurements in flash memory 20. To elaborate on this process, the MEMS gyroscope 36 continues to provide depth measurements to the low-power processor 42. As retrieval will cause the depth measurements to decrease relative to its prior value, the low-power processor 20 can use this change in values to determine when retrieval is taking place and issue the appropriate shutdown commands to the various components of the measurement unit 18. However, so as to avoid inadvertent shutdown of these measuring devices, in this embodiment, the shutdown commands are not issued until the MEMS gyroscope 36 again issues a depth value representing the modified desired depth value. [0083]When the drill string 30 has been retrieved to the surface, the user retrieves the handheld unit 14 and presses the "Retrieve Core Orientation" button of the membrane keypad 58. Pressing this button issues a command to the RF transceiver 24 to search for the handheld unit 12 with which it had established the previous communications channel. When the RF transceiver 24 identifies this handheld unit 12, the RF transceiver 24 of the downhole unit 12 and the RF transceiver 48 of the handheld unit 14 re-establish this communications channel. [0084]With the communications channel re-established the handheld unit 14 sends a command to the downhole unit 12 to forward on all of the stored data records 66. In response to this command, the handheld unit 14 communicates each such data record 66 stored in flash memory 22 to the handheld unit 14. [0085]The low-power processor 54 then operates to store the data records 66 in its own transitional memory 64. Once stored, the low-power processor 54 checks each data record 66 in turn to determine whether the measurements taken by the MEMS gyroscope 36 are considered potentially unreliable as described in the first -14 embodiment. If this is the case, then the data record 66 is appropriately marked to indicate that an orientation measurement should be calculated from the measurements taken by either the tri-axial accelerometers 38, or the tri-axial magnetometer 40. [0086]The low-power processor 54 then searches through these stored data records to determine the data record 66 closest in depth to the desired depth as indicated by the user. [0087]On identification of the relevant data record 66, the low-power processor 54 processes the data record 66 to determine the roll angle and inclination of the downhole unit 12 at the desired depth. If the data record 66 is not marked as anomalous, this calculation is based off the measurements of the MEMS gyroscope 36. However, if the data record is marked as anomalous, the calculation is based off the measurements of either the tri-axial accelerometers 38, or the tri-axial magnetometer 40. In either situation, the appropriate roll angle and inclination measurement is then conveyed to the user by way of the display 56. [0088] Following display of the roll angle and inclination values by way of the display 56, the user may seek to re-orient the retrieved core sample by pressing the "Re Orient Core" button of the membrane keypad 58. [0089]Once the "Re-Orient Core" button has been pressed, the handheld unit 14 uses the communications channel with the downhole unit 12 to issue commands to the downhole unit to commence the re-orientation procedure. Commencement of the re-orientation procedure involves re-starting the tri-axial accelerometers 38 and MEMS gyroscope 36 and transmitting the roll-angle measurement taken by these components to the handheld unit 14. [0090]The received roll-angle measurements are then compared with the roll-angle measurement displayed to the user. If the difference is positive, the user is directed to rotate the downhole unit 12, with core barrel still attached, in a counter-clockwise direction. If the difference is negative, the user is directed to rotate the downhole unit 12 in a clockwise direction. This process completes when the received roll-angle measurement corresponds with the displayed roll-angle measurement. Following -15 completion, the display 56 is updated to indicate to the user that the downhole unit 12, with core barrel still attached, has been successfully re-oriented. [0091]While each of the embodiments described above have designated the MEMS gyroscope 36 as the primary measuring device, it may just as easily act as the failover measuring device for either the tri-axial accelerometers 38 or the tri-axial magnetometers 40. In practice in the mining industry, this is more likely to be the case as the industry has a proven track record of taking orientation measurements with tri-axial accelerometers 38 and tri-axial magnetometers 40. Hence, the following combinations of primary and failover measuring arrangements are all considered to be within the scope of the present invention: * Primary - MEMS gyroscope 36; Failover - tri-axial accelerometers 38; * Primary - MEMS gyroscope 36; Failover - tri-axial magnetometers 40; * Primary - tri-axial accelerometers 38; Failover - MEMS Gyroscope 36; * Primary - tri-axial accelerometers 38; Failover - tri-axial magnetometers 40; * Primary - tri-axial magnetometers 40; Failover - MEMS Gyroscope 36; and * Primary - tri-axial magnetometers 40; Failover - tri-axial accelerometers 38. [0092] In order to determine when the primary measuring arrangement is producing anomalous measurements, additional or alternative measurement sensors 41 may need to be employed to those already described. In trying to determine whether the tri-axial magnetometer measurements 40 are anomalous, the tri-axial magnetometers 40 themselves may operate as an additional measurement sensor 41. [0093] It should be appreciated by the person skilled in the art that the above invention is not limited to the embodiment described. In particular, the following modifications and improvements may be made without departing from the scope of the present invention: * [0094]While the invention has been described with reference to two separate components - i.e. a downhole unit 12 and a handheld unit 14 - it is possible to integrate the functionality of the handheld unit 14 into the downhole unit 12 and thus run the system as a single unit. However, there are significant operational disadvantages to this approach which lead the applicant to prefer the two unit approach as described.

-16 * [0095]While the invention has been described with reference to connections being formed by matching male and threaded portions, this has been done as it is the most common form of connection to the art. Other means of connection may be employed without departing from the scope of the invention. * [0096]The MEMS gyroscope 36 may be modified to also include either or both of the tri-axial accelerometer 38 or the tri-axial magnetometer 40. * [0097]Storage means 20 in forms other than flash memory may be used with the invention. However, due to the environment in which the invention operates, storage means 20 with no moving parts are to be preferred to ensure reliability. Furthermore, the capacity of the storage means 20 may be more or less than the four gigabytes indicated in the embodiments described above. * [0098]Communications between the handheld unit 14 and downhole unit 12 may be established by means other than a radio frequency transceiver. For instance, near-field communications technology, wi-fi or BluetoothTM technologies may be employed instead of the RF transceiver. Similarly, the communications channel may be established by means of a wired connection, such as a USB connection. * [0099]The user interface 50 as described above may be replaced with other forms of interaction with the user without departing from the scope of the invention. For instance, the user interface 50 may take the form of a touch screen display. * [0100] In a similar fashion, the handheld unit 14 may take the form of a tablet computer or smart phone running app software to achieve the functionality described above. * [0101]The downhole unit 12 may operate to perform the series of self tests on power up rather than on specific receipt of a command from the handheld unit 14. * [0102] Rather than using the handheld unit 14 to indicate when the downhole unit 12 is ready for operation, the downhole unit 12 may include an indicator light for indicating its operational status. Alternatively, the indicator light may -17 be replaced with a speaker that emits a predetermined sound to indicate that it is ready for operation. * [0103] In setting up the operational parameters of the downhole unit 12, the user may be able to specify the sample rate of all components forming the measurement unit 18. Where the user so specifies the sample rate, if any of the components forming the measurement unit 18 have a faster sample rate, the software executed by the low-power processor 42 may operate to average the measurements received within the user defined sample rate period to form an overall representative measurement. * [0104]Alternatively, the low-power processor 42 may simply operate to take the last measurement value received from that component within the user defined sample rate period. * [0105]While each of the above embodiments have been described with reference to depth as the determining factor for measurement, the systems 10, 100 so described may be modified to work on a time basis or quasi-time basis. Operation on a quasi-time basis generally sees a "depth" value being entered, but this "depth" is based on drilling movement rates as a function of time. * [0106] Similarly, if the embodiments work on a time basis, rather than requiring the user to enter the time at which the measurement should be taken prior to drilling, the user may operate to press a "Take Measurement" button on the membrane keypad 58. Pressing the "Take Measurement" button then causes the handheld unit 14 to record the time that the button was pressed and to seek to correlate this time with the time of the measurements taken by the downhole unit 12 following its retrieval. It should be noted that in order for this system to work accurately, a further step of synchronising the time counters of both the handheld unit 14 and the downhole unit 12 needs to be undertaken. * [0107]The measurements desired by the user may be values obtained from processing the raw measurements taken from one or more of the components of the measurement unit 18. Furthermore, this processing may take place by either of the low-power processors 42, 60. Alternatively, this processing may be inherent in the circuitry of the component concerned. * [0108]One or more of the components forming the measurement unit 18 may provide their signals in analogue form. Where this occurs, the system 100 -18 may require an analogue to digital convertor to ensure that such signals can be handled by the processing unit 20 and/or storage means 22. * [0109]The various methods employed by the described embodiments for turning on the various components of the measurement unit 18 may be interchanged without departing from the overall scope of the invention. * [0110] Furthermore, in variations of the first embodiment, the value presented to the user as the measured value may be either a value determined by position (i.e. first measurement, last measurement, fifth measurement, etc. taken at the relevant depth) or by function (i.e. an average of all measurements taken at the relevant depth) or by a condition "(i.e. the measurement taken just prior to the MEMS gyroscope 36 recording a reversal in drilling direction). * [0111] In situations where the system 10, 100 is not able for whatever reason to meet a desired depth for measurements, the system 10, 100 may either operate to present a value indicative of this fact or provide measurement values recorded at the closest depth to the desired depth. In the latter situation, the values displayed may be highlighted so as to clearly show the user that they are not measurements taken at a desired depth. * [0112]Depending on the sample rate employed by the system 10, 100 the user may need to wait a period of other than one minute to obtain stationery measurements. * [0113]In variations of the second embodiment, the user may be asked to specify the type of core orientation measurements they wish to take in a similar manner to the selection of the azimuth recording component of the third embodiment. Such a configuration would allow the user to specify either angular orientation (i.e. inclination), rotational orientation (i.e. roll angle) or both angular and rotational orientation. * [0114]The handheld unit 14 in the second and third embodiments of the invention, may issue commands to the downhole unit 12 only to transmit the desired data records 66, rather than all the data records 66. * [0115]When re-orienting the core in accordance with the second embodiment of the invention, the extent and direction which the core must be rotated to achieve re-orientation may be indicated to the user by either visual or audible -19 cues. For instance, the user may be presented with a series of high tone beeps to indicate that clockwise rotation is required and a series of low tone beeps to indicate that counter-clockwise rotation is required. The period between beeps can then act as an indication of the extent of rotation required (ie. the closer together the beeps are, the closer the core is to being re oriented). In yet another alternative, the display 56 may present a series of arrows to the user indicating the direction in which the core must be rotated. In this configuration, the length of the arrows may be used to indicate the extent of rotation required (ie. larger arrows indicate that the core is still a long way of re-orientation). * [0116] The handheld unit 14 may be able to communicate one or more desired measurements to an external processing device and/or storage means such as a desktop computer, tablet computer, smart phone or portable hard drive. * [0117]The invention as described may also be adapted for use in a real-time environment. In doing so, the measurements taken by the various components may be collated for transmission to a handset or other data receiving device on the surface by way of a wireline. As wirelines are well known within the industry and to the person skilled in the art they will not be described in more detail here. The invention may also be modified to operate in real-time using wireless data communication processes such as, for example, mud-pulse telegraphy or radio communication. In doing so, the need to set a depth value from which measurements are to be taken may not be required. * [0118] In a variation of the invention configured as per the prior bullet point, the wireline system may operate as the primary means of data collection. However, the data recording and retrieval components and methodology as described in the other embodiments may be used as a back up system to ensure that important measurements are not inadvertently lost due to data communications problems with the wireline or wireless system. * [0119]The spacer tube 102 may be omitted. * [0120] Rather than marking anomalous records for later reference, the processor may simply operate to replace the primary measurement with an alternative measurement in the data record 66.

-20 [0121] It should be further appreciated that even more embodiments of the invention incorporating one or more of the aforementioned features, where such features are not mutually exclusive, can be created without departing from the invention's scope.

Claims (5)

1. A multifunction orientation system comprising: a primary measuring means for measuring a first drilling characteristic from which an orientation measurement can be determined; at least one secondary measuring means for measuring a second drilling characteristic from which an orientation measurement can be determined; and where when the multifunction orientation system determines that the current measurements of the primary measuring means are anomalous, the at least one secondary measuring means operates to take measurements, the system thereafter operable communicate the orientation measurement determined from the measurements recorded by the at least one secondary measuring means as the proper orientation measurement.

2. A multifunction orientation system according to claim 1, where the primary measuring means is a gyroscope and the at least one secondary measuring means includes at least one of the following: tri-axial accelerometers; tri-axial magnetometers, or where the primary measuring means is a tri-axial accelerometer and the at least one secondary measuring means includes at least one of the following: tri-axial magnetometers; gyroscope, or where the primary measuring means is a tri-axial magnetometer and the at least one secondary measuring means includes at least one of the following: tri-axial accelerometers; gyroscope.

3. A multifunction orientation system according to claim 1 or claim 2, further including at least one additional measurement sensor, the at least one measurement sensor operable to measure at least one characteristic that can bias the measurements taken by the primary measuring means, the multifunction orientation system operable to determine whether measurements of the primary measuring means are anomalous based on correlated measurements taken by the at least one additional measurement sensor.

4. A multifunction orientation system according to any preceding claim incorporating a core barrel adaptor, the orientation measurement to be determined by the -22 primary and secondary measuring means and communicated to the user being the orientation of the core barrel adaptor.

5. A method of determining the orientation of a device comprising the steps of: measuring a first drilling characteristic from which an orientation measurement can be determined; measuring at least one second drilling characteristic from which an orientation measurement can be determined; determining whether the measurements of the first drilling characteristic are anomalous and, if so determined, communicating to the user the orientation measurement determined from the measurements of the at least one second drilling characteristic as the proper orientation of the device.