[0001] This application claims convention priority from Australian provisional patent application 20149031 16 filed on 1 1 August 2014, the contents of which are hereby incorporated by reference.

FIELD OF THE INVENTION

[0002] The present invention relates to monitoring of drilling parameters of drilling operations.

[0003] The present invention is particularly applicable to, but not limited to, onshore rock drilling, such as surface or underground drilling, relating to exploration and extraction of resources utilising a sub, such as a floating spindle sub.

[0004] The present invention relates to a (drill) sub or floating sub (such as a floating cushion sub or FKS) for surface use for onshore drilling operations.

BACKGROUND TO THE INVENTION

[0005] Drilling is presently a key operation in the process of exploiting underground resources and involves a set of processes for breaking and removing rock to produce boreholes.

[0006] Rotary drilling relies on a combined mechanical/hydraulic system for energy and material transport. The mechanical part is composed of a drill bit, a series of pipes (drillstring, drill collars or rods), a drive system and a mast. The hydraulic part consists of drilling fluid (mud), pumps and a transport channel. The drilling fluid is pumped down through the pipes and flows back through the annulus between the pipes and the borehole wall.

[0007] A drill string is rotated by the drive system, such as a top drive system, to rotationally drive the drill bit downhole at the distal end of the string of drill pipes.

[0008] A surface use drill sub provides an adapter connection between the drill tubes of the drill string and the top drive. The sub provides a threaded adapter connection to ensure correct threading to the upper end of the drill tubes. The sub provides a means of making up and breaking out threaded connections at the upper end of the drillstring at the surface without damaging threads of the drill pipes.

[0009] A floating sub or floating cushion sub also prolongs bearing and gear life of the rotary top drive.

[0010] A sub, such as a floating sub, of the known type is typically provided at the surface between the drive system and the upper end of the string of drill pipes.

[001 1] 'Floating spindle subs' (or, more simply, floating subs) are often mounted between the drillstring and the top drive to allow a limited amount of axial movement. The sliding spindle of the floating sub permits the drill operator to lower the top drive with minimal force being applied to the top drive spindle and drillstring components. Additionally, a floating sub allows the threads of the drillstring to float together or apart, during rotation without any axial movement of the top drive. This degree of movement helps to prolong the lifespan of the top drive.

[0012] A longitudinal hole through the floating spindle centre also permits the drilling fluid to be pumped down to the drill bit. [0013] Nowadays, drilling parameters are monitored during mineral resource exploration drilling operations. Such monitoring is generally limited to (i) pressure sensors measuring fluid pressure mobilised in hydraulic cylinders (providing axial thrust on the drill string) and in hydraulic motor (rotating the drill string), and (ii) simple displacement sensor to measure rate of penetration. Uncertainties associated to those measurements are often large and can lead to erroneous estimate of down-hole drilling parameters (in particular force mobilised at the bit- rock interface).

[0014] Improving the precision and/or resolution of drilling measurement is very valuable to: (i) reduce uncertainties during the monitoring of drilling operations; (ii) report and compare drilling performance with scientific objectivity; (iii) optimise drilling performance in real time, but also the design of drilling procedure and strategy; and (iv) develop drilling simulation and to train drilling personnel.

[0015] Improving quality of measurement with minimum if any need for retrofitting rigs is an important rationale of at least one form of the present invention.

[0016] Therefore, there is a desire to provide an improved drill sub, floating sub or apparatus for forming part of an instrumented drill sub or floating sub at the surface with capability of providing measurement of at least one drilling parameter.

SUMMARY OF THE INVENTION

[0017] With the aforementioned in mind, an aspect of the present invention provides an electronically instrumented apparatus to form part of a sub assembly for a drilling operation, the apparatus including at least one sensor mounted to the apparatus and arranged to detect, measure or record at least one drilling parameter during a drilling operation. [0018] Another aspect of the invention provides an electronically instrumented apparatus for use with a surface employed sub assembly for a drilling operation.

[0019] Preferably the apparatus is for use with a floating sub, the apparatus including a first member having a portion to engage for relative sliding motion with a first part of a sliding coupling of the floating sub, and at least one sensor mounted to the apparatus and arranged to detect, measure or record at least one drilling parameter during a drilling operation.

[0020] The apparatus is preferably employed for use at the surface. For example, in conjunction with a sub aiding connection of the drill pipes to a drive arrangement.

[0021] Preferably the present invention is applied to onshore rock drilling, such as surface or underground drilling e.g. relating to exploration and extraction of resources utilising a sub.

[0022] The apparatus may include one or more fastening means to releasably attach the first member in fixed relationship to a second part of the sliding coupling. Such fastening means may include one or more bolts to releasably attach the apparatus to the sliding coupling.

[0023] Preferably, the sliding coupling and the apparatus together form the floating sub.

[0024] The apparatus may include a spigot, which inserts into the first part of the sliding coupling, the spigot having a conduit to allow fluid flow through the first member of the apparatus.

[0025] The apparatus may include a drill string connector or adapter, so as to enable attachment of the apparatus to the upper end of a drillstring or drill tube. For example, the first member may include or be connected to a drillstring connector.

[0026] The conduit may therefore provide a passage for fluid flow between an opening into the spigot and the drillstring connector.

[0027] The at least one sensor may include at least one strain gauge mounted to the apparatus to detect tensile/compressive forces. One or more strain gauges may be provided to detect torsional force.

[0028] The at least one strain gauge may be mounted to an exterior surface of the first member, such as to a tube portion of the first member. The at least one strain gauge may be provided to detect weight on bit, for use in controlling rate of penetration and /or drill bit wear characteristics.

[0029] The apparatus may include at least one signal processor and power supply mounted to the first member.

[0030] When the sliding coupling and apparatus are assembled together, the conduit through the first member and a conduit through the first part of the sliding coupling may provide a fluid flow passageway through the floating sub.

[0031] At least one said sensor may include at least one pressure sensor or at least one accelerometer or a combination of at least one pressure sensor and at least one accelerometer. The pressure sensor(s) may be provided to detect pressure and /or change in pressure within the conduit. The at least one accelerometer may be provided to sense acceleration/deceleration for use in determining a number of parameters, such as off-axis acceleration, vibration, rpm, downwards/upwards movement of the drill string/drill bit etc.

[0032] At least one transmitter may be arranged and configured to transmit signals or data obtained from signals from the at least one sensor. [0033] A further aspect of the present invention provides a sub for an onshore drilling operation, the sub including at least one sensor arranged to measure, detect and/or record at least one drilling parameter. The sub is preferably an electronically instrumented sub.

[0034] One or more forms of the present invention provide(s) a (drill) sub for use in a drilling operation, the sub being instrumented for sensing one or more parameters relating to the drilling operation, such as weight on bit (WOB), fluid pressure (such as in a drilling mud), torque on the drillstring (such as applied by a top drive), rate of penetration (ROP) of the drill bit.

[0035] Preferably the sub includes a drive system connector, a drill pipe connector, and a portion between the drive system and pipe connectors.

[0036] The portion between the drive system and pipe connectors may include/accommodate limited axial movement between the drive system connector and the pipe connector.

[0037] The sub may include a floating sub or floating cushion sub.

[0038] The provision of at least one sensor within the sub improves direct measurement and accuracy of the drilling parameter(s) by bringing the sensor(s) below the uppermost end of the drill string where rotational (torque) and longitudinal drive forces transmitted to the drill pipes are applied.

[0039] Preferably the floating sub includes a floating spindle sub. The floating spindle arrangement providing a sliding coupling accommodating a limited amount of axial position adjustment between the drive system connector and the drill pipe connector. Preferably the coupling provides a sliding splined coupling.

[0040] It has been realised that adding a separate instrumented device between the drive system and the sub or floating sub, or between the sub or floating sub and the upper end of the drillstring occupies greater space (greater height) and therefore reduces the drill stroke for the drill rig, which reduces productivity.

[0041] Furthermore, reducing the stroke by adding an additional device also risks damage to the additional device by striking the drill rig at the end of the stroke.

[0042] Furthermore, operators who are used to a standard sized floating sub may not appreciate or expect the change in space available for a drill stroke because of the additional device. Thus, additional training of personnel is likely to be required, and thereby add to operational costs.

[0043] It is desirable to provide an instrumented floating sub for drilling operations wherein the instrumented floating sub takes up no more height than a standard or regular floating sub. Furthermore, an instrumented floating sub of the present invention can be provided to fit within an external envelope of such a known or standard floating sub.

[0044] It will be appreciated that an instrumented floating sub according to one or more forms of the present invention may be arranged and configured to fit within a space envelope of a known standard floating sub. No additional devices (e.g. 'bolt on' devices) are required between the floating sub and the top of the drillstring that would otherwise reduce the stroke distance for the drill operator.

[0045] Thus, one or more forms of the present invention provides an instrumented floating sub that is a direct replacement for known floating subs and is therefore immediately acceptable and employable by drill rig operators.

[0046] The present invention may therefore provide or relate to a floating spindle drill head sub that includes or is provided with sensors for measurement of at least one drilling parameter. [0047] Preferably the at least one sensor includes one or more of a strain gauge arrangement, at least one flow sensor and/or pressure sensor, and at least one accelerometer, or combinations of one or more thereof.

[0048] The at least one sensor may be provided as part of or connected to a measurement device.

[0049] Preferably the measurement device includes electronics arranged and configured to receive and preferably process measurement signals from the at least one sensor.

[0050] The at least one sensor may include a force measurement sensor arrangement connected or mounted to the sub.

[0051] Preferably the force measurement sensor arrangement includes at least one strain gauge to measure forces acting on the sub.

[0052] Measurement of torque or axial thrust at or near the top/uppermost end of the drillstring can be used to infer: (i) frictional losses mobilised between the surface and the bottom of the hole (friction between the drilling rods and the well bore walls or casing or surface equipment); and (ii) axial (weight-on-bit) and torque (torque-on-bit) mobilised at the bit-rock interface.

[0053] The strain gauge arrangement may be mounted on a portion of the sub, for example, mounted to a central tube portion of the sub. Thus, the strain gauge arrangement may include one or more strain gauges connected to a surface of e.g. the central tube portion, of the sub. The strain gauge(s) detect(s) axial and/or torque forces e.g. through the central tube portion.

[0054] Measurement may be of positive or negative force components (tension or compression, clockwise or counter-clockwise torque) or of both positive and negative such force components as they arise. [0055] The sub may include at least one pressure sensor used to measure pressure of the drilling fluid flowing through the internal bore of the sub. The fluid is used to carry the cutting away from the drill bit back to the surface but also cool the bit and reduce the friction between the rods and the well bore.

[0056] The sub according to one or more embodiments of the present invention may also include a measurement of the flow rate of the drilling fluid flowing through the internal bore of the sub. The sub may therefore include at least one fluid flow rate sensor, such as an ultrasonic (Doppler Effect) flow rate sensor or a transit time flow rate sensor, detecting the rate of flow of fluid through the central tube of the floating sub.

[0057] The sub may also include one or more of a drilling fluid viscosity sensor and a drilling fluid temperature sensor. For example, viscosity of the drilling fluid may be sensed when pumping of the drilling fluid has ceased. Temperature of the drilling fluid may be sensed while the drilling fluid is being pumped or not pumped. Sensing temperature of the drilling fluid can be conducted on the fluid flow to the drill bit and/or on the fluid flow return from the drill bit. Thus, temperature difference can also be detected by the sub or determined remotely from the sensed temperature signals.

[0058] The sub may also include capability to sense displacement towards or away from the (borehole). The sub may thus include at least one sensor to measure rate of penetration (ROP) of the drill bit. Sensing displacement or rate of penetration can be used in conjunction with the accelerometer(s) to determine the optimal depth of cut and thereby improve drilling performance.

[0059] The ability to monitor fluid pressure and force mobilised at the bit-rock interface is of importance to monitor and possibly mitigate the occurrence of bit wear, bit plugging, inadequate bit cleaning, and excessive vibrations and eventually optimise drilling performance. [0060] Furthermore, frictional forces mobilised between the borehole walls and the drill string, can lead to excessive wear of the drill rods and/or excessive loading of the thread, but also overload of the drill rig leading to excessive wear but also excessive energy consumption (fuel, electricity).

[0061] Monitoring of frictional forces (torque and drag) mobilised between the drill string and the borehole walls is also valuable to track the evolution of "directional" holes and make sure rig capabilities are sufficient to complete the hole.

[0062] Evolution of borehole cleaning can also be tracked by proper monitoring of torque and drag forces.

[0063] The instrumented sub (such as a floating sub) of one or more forms of the present invention may therefore provide essential data to monitor drilling efficiency (ratio of energy provided on surface to the rods to energy delivered at the bit) but also rig efficiency (energy provided to the rig to energy delivered at the bit). The instrumented sub and/or the measurement device are for use at the surface i.e. not employed downhole.

[0064] Acceleration of the sub or part thereof may also be recorded. Accelerations recorded at or near the top of the drill string provide a signature of the drill string vibrations.

[0065] Furthermore, centripetal accelerations when properly located yield a measure of the drillstring instantaneous angular velocity.

[0066] The measurement device may include electronics, and preferably may include at least one wireless communications device, preferably including at least one transmitter and/or receiver to respectively transmit or receive data relating to measurements obtained by the at least one sensor of the sub. [0067] The at least one wireless communications device may include one or more antennas (antennae) for transmitting and/or receiving data. More than one antenna may be provided to ensure or improve data transmission/reception.

[0068] The wireless communications device may provide two-way communications with an external computer, such as a PC. The communications may include data download, parameters setup (scanning rate, sensor configuration values) etc.

[0069] Hardware communication, such as by a plug in connector to the electronics device, may be provided via an electrical connector arrangement. This allows for debugging, software (firmware) upgrades and fault diagnosis etc.

[0070] Data functionality of the sub provides for automatic monitoring and management of measurement channels, automatic battery power checking (with optional low battery warning), an ability to select sensor scanning rate(s) and/or channels and the ability to perform computational calculations, such as to reduce scanning rates when drilling operations cease for a period of time or when connection of a pipe is being made or removed i.e. when the drilling operations are not presently happening.

[0071] The sub (such as a floating sub) of one or more forms of the present invention may incorporate a processor or embedded computer. Such computing/processing facility may include processing and computing algorithms, such as filtering, segmentation and Fourier analysis.

[0072] It will be appreciated that at least one form of the present invention provides a sub (such as a floating sub) for use in surface drilling operations, wherein the sub includes weight and torque measurement acting at the upper end of the drill rod assembly. [0073] Preferably the floating sub includes first and second sections, the first section arranged to connect to the drive mechanism and the second section arranged to connect to an upper end of the drill string assembly and a spline arrangement by which the first and second sections can reciprocate with respect to one another while concurrently being held non-rotatable with respect to one another.

[0074] The sub may include an axial bore to permit fluid to flow through the sub to the drill bit via the drill pipes.

[0075] A further aspect of the present invention provides a sub-assembly for connection to a sub (such as to a floating sub) for use in a surface drilling operation.

[0076] Preferably the sub assembly includes connection means arranged and configured to connect the sub assembly to a floating sub, and drill pipe connection means arranged and configured to connect the sub assembly to an upper end of the drill pipe.

[0077] Alternatively, connection to the top drive end of the floating sub may be provided such that the sub assembly would connect between the drive system and the floating sub.

[0078] Preferably the sub assembly includes a measurement device including at least one of an axial force sensor to detect axial forces (such as compressive and/or tensile forces), a rotational force sensor to sense torque applied to the drill pipe by the drive mechanism and a pressure sensor to sense drilling fluid pressure within the sub assembly, or a combination of two or more thereof.

[0079] Another aspect of the present invention provides a measurement device for incorporation with a sub (such as a floating sub) used on drilling operations. The measurement device enables the sub, and therefore the drillstring, to be instrumented and gather data relating to the drilling operation. Preferably real time drilling can be monitored by providing prompt if not near instantaneous data relating to one or more monitored drilling parameters, such as WOB, ROP, RPM, torque, pressure etc.

[0080] The measurement device may be provided as a sub assembly arranged to connect to a floating sub. Thus, a standard or known floating sub can be adapted or augmented to have drilling parameter measurement capability.

[0081] The measurement device may be provided as a device mounted onto or in a sub, such as a floating sub. The measurement device may attach to the sub. The measurement device may be removable from the sub for replacement (such as if faulty or the battery requires replacing). One measurement device may communicate data to a second measurement device (such as for backing-up data or the second measurement device replacing the first measurement device and maintaining data continuity.

[0082] The measurement device may include an electronics module and at least one sensor may be provided for mounting to a standard floating sub.

[0083] The electronics module may include at least one processor to provide onboard signal processing of signals obtained from the at least one sensor.

[0084] The at least one sensor may include one or more of an axial force sensor (such as for compression or tension sensing - e.g. one or more strain gauge arrangements) and/or one or more torque sensors (such as strain gauges - e.g. metal foil strain gauges).

[0085] Rotational speed sensing may also be provided by the module and at least one accelerometer. Thus, RPM and acceleration (rate of change of RPM) and preferably jerk (rate of change of acceleration) may be detected and reported. [0086] Thus, the weight (such as weight-on-bit) and preferably torque-on-bit may be estimated from surface measurements.

[0087] Wireless communication between the sub, sub assembly or the measurement device and a computer will facilitate monitoring of the at least one drilling parameter, and can facilitate transfer of data for display (to the driller), monitoring and interpretation for performance and maintenance purposes.

[0088] One or more forms of the present invention advantageously instruments a drill sub, such as a floating sub, for use at the surface for onshore (mineral or so called 'hard rock') drilling operations.

[0089] One or more specific embodiments of the present invention will hereinafter be described with reference to the drawings. The embodiment(s) that follow are exemplified in relation to a floating sub. However, it will be appreciated that one or more embodiments of the present invention is/are applicable to other surface drill subs unless otherwise stated or limited by subsequent amendment.

BRIEF DESCRIPTION OF THE DRAWINGS

[0090] One or more embodiments of the present invention will hereinafter be described with reference to the accompanying figures, in which:

[0091] Figure 1 shows an example of a known floating sub.

[0092] Figure 2 shows a floating sub incorporating at least one embodiment of the present invention.

[0093] Figure 3 shows at least one embodiment of the present invention in situ in relation to a top drive arrangement. [0094] Figure 4 shows an external view of an embodiment of the present invention.

[0095] Figure 5a shows a side-on exploded view of separate sections of a floating sub with instrumentation unit/device according to an embodiment of the present invention.

[0096] Figure 5b shows a vertical cross section through the separate sections shown in Figure 5a, as indicated by section line B-B.

DESCRIPTION OF PREFERRED EMBODIMENT

[0097] Figure 1 shows an example of a known type of floating sub 10. The floating sub has a central body 12 housing an axially sliding coupling (such as a spline) arrangement accommodating a variation in length of the floating sub. The housing separates two end opposed connectors, an upper connector 14 for attachment to a top drive arrangement, and a lower connector 16 for attachment to a drill pipe.

[0098] As described above, the sliding coupling allows for a vertical axial degree of freedom when adding or removing pipe sections. This avoids the need for the top drive to move up or down any significant distance when adding or removing sections of drill pipe to the drill string. Thus, damage through misalignment or poor handling of the top drive (drive system) is avoided when adding or removing pipe sections.

[0099] In use, the upper connector typically has an external thread and the lower connector an internal thread.

[00100] Figure 2 shows an alternative floating sub 20 according to an embodiment of the present invention. The floating sub includes a first (upper) connector 22 to connect the sub to a top drive arrangement, and a second (lower) connector 24 to connect the sub to the upper end of a drill pipe. Thus, the floating sub of the present invention can directly replace a standard floating sub without need to alter or replace other standard drilling equipment.

[00101] The floating sub 20 has a first body portion 26 housing a sliding coupling 21 to provide variation in length in the floating sub, as in a standard floating sub. The sliding coupling 21 has first 30 and second 32 parts, which slide relative to one another, such as by a sealed spline arrangement, to provide the required length variability. The first part is connected to the first upper connector 22, and it moves relative to the second part forming part of the first body portion 26.

[00102] A second body portion 28 connects to the first body portion and accommodates the at least one sensor arrangement. The second body portion has a first adapter 34 facilitating connection of the second body portion to the first body portion housing the sliding coupling, and a second adapter 36 facilitating connection of the second body portion to the upper end of the drill pipe(s) (see Figure 3).

[00103] A tube section 38 extends between the first 34 and second 36 adapters. The tube section is hollow to allow fluid to flow through the floating sub, through the drill pipes, to the drill bit. The first body portion housing the sliding coupling is also correspondingly hollow.

[00104] The second body portion houses a measurement device 40 incorporating an electronics unit and connected to the at least one sensor. The measurement device receives signals from the at least one sensor relating to one or more drilling parameters being monitored, such as weight on bit and torque.

[00105] Preferably data relating to the sensed drilling parameters is processed on-board the measurement device by a processor. However, such data may be stored and transmitted wirelessly or transferred by wired connection for off-board, remote processing.

[00106] Figure 3 shows an example of a floating sub according to an embodiment of the present invention mounted between a top drive 42 and the upper end of a drill pipe 44.

[00107] Figure 4 shows a side-on view of a floating sub 20 with electronic instrumentation unit 40 according to an embodiment of the present invention.

[00108] Figures 5a and 5b show detail of the floating sub 20 with sliding coupling accommodating the variability in length.

[00109] In particular, Figures 5a and 5b show views of separated floating sub 20 components providing an upper sliding coupling 21 and a lower spigot member 34.

[001 10] The upper sliding coupling includes a first component 30 slidably received within a second component 32.

[001 1 1] Sliding seals 50 (see Figure 5b), such as O-ring seals, accommodate relative movement between the first and second components, and prevent fluid from leaking past the seal between the first and second parts of the sliding coupling and prevent dirt entering the coupling. These sliding seals 50 are external to the first component and internal to the second component.

[001 12] The lower spigot member 34 includes an electronic instrumentation device 40 incorporated therewith. The electronic instrumentation device 40 can be provided as a discrete unit for mounting to a component of the sliding sub, such as to the lower spigot member. Alternatively, the electronic instrumentation device can be provided as separate components mounted to a housing on the lower spigot member. [001 13] The lower spigot member includes a flange 60 with apertures 61 to receive bolts 62 therethrough to bolt the lower spigot member to the second component of the sliding coupling.

[001 14] A lower end 24 of the spigot member 38 includes an internally threaded opening 39 to connect the sub to the upper end of a drillstring.

[001 15] An external cover 41 can be provided to protect the components of the electronic instrumentation device.

[001 16] Additional sliding seals 49 are provided to seal during relative movement between a spigot end 48 of the spigot member 34 and an internal opening 45 of a central channel or passage 47 through the sliding coupling.

[001 17] A central tubular stem 48 provides a channel 46 through which fluid can flow through the floating sub and about which the first (upper) part 30 of the sliding coupling slides and provides continuity for fluid flow through a corresponding channel or passage 47 thereof.

[001 18] The measurement device 40 houses electronics 52 connected to a strain gauge arrangement 54 having one or more strain gauges (e.g. strain gauges 54a, 54b) bonded to an exterior surface of the tube section 38, and thereby protected within the sub.

[001 19] Such strain gauges measure compressive and/or tensile forces acting on the drill pipe and therefore acting on the drill bit. Weight on bit can therefore be monitored and adjusted for.

[00120] According to one or more embodiments of the present invention, a standard sub can be modified by adding a measurement device to the standard sub. The measurement device optionally includes the spigot member (upper adapter) 34 arranged to mount to a lower portion of a standard sub sliding coupling.

[00121] Wireless communication between the sub and a computer will allow control of the sub and regular transfer of data for display (to the driller), monitoring and interpretation.

[00122] One or more pressure transducers 56 is/are provided to monitor fluid pressure within the central tube of the sub. Figure 4 shows an access port 55 to insert or remove a pressure transducer 56.

[00123] Accel era meters detect angular velocity of the rotating sub (and therefore rotation of the drill string). RPM can be monitored and controlled to optimise wear on the drill bit, especially when controlled in conjunction with weight on bit. Thus, improved drilling performance can be achieved utilising the measurement device within a floating sub arrangement without the need to replace or modify other drilling equipment. Improved drilling efficiencies can be obtained, with less likelihood of unexpected premature wear or failure of the drill bit.

[00124] Importantly, the task of optimising drilling performance (i.e. optimising effective drilling and efficient drilling) can be removed from drilling personnel otherwise relying on experience and the vagaries of 'feel'.

[00125] Benefits of embodiments of the present invention include, but are not limited to; i) electronically and accurately monitoring of drilling performance, ii) monitoring and control can be automatic - for example, drilling parameters (such as weight on bit, displacement, RPM, torque, pressure within the drill string) can be preset, and iii) if actual drilling parameters go outside of the preset range, an alert can be automatically provided to personnel or automatic control can modify drilling operations to bring the actual drilling parameters back within required parameters e.g. by reducing weight on bit, slowing down RPM or reducing torque.

[00126] Measurements carried out by the measurement device and

arrangement of sensors includes:

• Force (such as weight-on-bit): in the range 300N to 300 kN

• Torque: in the range of 0-10 kN.m

• Acceleration: in the range of 0-150 g (-0-1500 ms ^"2 )

[00127] Data acquisition relating to the parameter(s) monitored as envisaged can be at a scanning rate in the range of tens or low hundreds of Hertz. It will be appreciated that scanning rate may cease or slow during non-drilling.

[00128] Scanning rate may be matched to RPM - preferably with an objective of about 1 to 10 points per bit revolution.

[00129] One or more embodiments of the present invention can further include a sleep mode function, whereby, the device or system can enter a power saving standby 'sleep mode' between successive measuring points or operations.