Wear monitoring method and system for monitoring wear of components on a drill RIG, and a drill RIG comprising such a system

Abstract

The invention relates to method of operating a drill rig (100), the method comprising a process of monitoring wear of components (105, 106, 132, 133, 135) of a drill string (107), which process comprises: identifying (201) a first component (105, 106, 132, 133, 135) of the drill string (107), moving (202) a forcing unit (306, 401, 501) into a clamping position (P) in which the forcing unit (306, 401, 501) forces the first component (105, 106, 132, 133, 135) against a support surface (308, 402, 502), determining (203) the clamping position (P) of the forcing unit (306, 401, 501) by means of a position sensor (305, 403, 503), determining (204) a wear condition (WC) of the first component (105, 106, 132, 133, 135) based on the determined position clamping (P), determining (205) if the determined wear condition (WC) exceeds a first wear condition guideline value (WC1), or if the determined wear condition (WC) diverges from a second wear condition guideline value (WC2) by more than a threshold margin (MTH).

Description

[0001] WEAR MONITORING METHOD AND SYSTEM FOR MONITORING WEAR OF COMPONENTS ON A DRILL RIG, AND A DRILL RIG COMPRISING SUCH A SYSTEM

[0002] TECHNICAL FIELD

[0003] The invention relates to a method of operating a drill rig, a wear monitoring system and a drill rig comprising such a system. Further, the invention relates to a method performed by a control unit, or a computer connected to the control unit, to a computer program product, and to a computer-readable storage medium.

[0004] BACKGROUND

[0005] In the technical field of rock drilling, drilling may be formed in different directions on different types of drill rigs. A common feature of such different types of drill rigs is that when long drill holes are bored several drill pipes are attached to each other to form a drill string of a desired length.

[0006] These drill pipes, and other components of the strings wear over time due to contact with surrounding drill material such as sand and rocks. Due to the wear the diameter of the components will diminish over time. The pipes need to be exchanged before their diameter reaches below a crucial width where they risk breaking or bending. Also, for other components of the drill string the wear of the components needs to be monitored such that a correct action may be taken based on the wear of the specific components.

[0007] In the state of art, it is therefore known to control the wear of drill string components by means of specific arrangements such that the worn drill string components may be exchanged in time.

[0008] SUMMARY

[0009] It is an object of the invention to provide a method, a system and a drill rig configured to monitor the wear of drill string components during operation of the drill rig.

[0010] According to a first aspect the invention relates to a method of operating a drill rig, the method comprising a process of monitoring wear of components of a drill string, which process comprises:

[0011] - identifying a first component of the drill string,

[0012] - moving a forcing unit into a clamping position in which the forcing unit forces the first component against a support surface, determining the clamping position of the forcing unit by means of a position sensor,

[0013] - determining a wear condition of the first component based on the determined clamping position,

[0014] - determining if the determined wear condition exceeds a first wear condition guideline value, or if the determined wear condition diverges from a second wear condition guideline value by more than a threshold margin.

[0015] The invention presents a feasible, yet effective manner of controlling the condition of components comprised in a drill string.

[0016] In embodiments of the method the first wear condition guideline value corresponds to a wear condition set to indicate that the first component should be exchanged.

[0017] This embodiment makes it possible to inform an operator, a service person or other office personal when it is time to exchange a component.

[0018] In embodiments of the method the second wear condition guideline value corresponds to a historic wear condition of the first component, and wherein the threshold margin is set to indicate that a periodic wear between the determined wear condition and the registration of the second wear condition guideline value is outside a range of an acceptable periodic wear.

[0019] By registering the wear over time, it will be possible to note wear for each operation and relate it to current operation conditions. From this, it is also possible to analyse data and to optimise operational parameters so as to provide a drilling operation with less wear on the components.

[0020] The first component of the drill string may be a drill bit, a drill pipe, a deck bushing, a bit sub, a roller stabiliser, and / or a hammer.

[0021] In embodiments of the method the clamping position is determined on a periodic manual or automatic schedule, or each time the first component is connected to and / or removed from the drill string, and wherein a corresponding wear condition is registered, manually or automatically, each time the clamping position is determined to provide a representation over time of the wear of the first component of the drill string. In embodiments of the method, the clamping position may also be manually or automatically determined in a periodic fashion. The clamping position may also be manually or automatically determined during other manual or automated operations, or as a part of a preventative maintenance or shift inspection.

[0022] Some drill string components other than the drill pipes for a multi-pass machine are only connected to and / or removed from the drill string when they wear out such that wear of them would need to be manually or automatically determined when they are connected to and / or removed from the drill string.

[0023] The process of monitoring wear of components of a drill string as disclosed herein may be combined with other manual or automatic operations for handling the drill string components performed by other devices, such as a bit changer. This has advantages of monitoring wear of the components in the drill string while the bit changer is in operation.

[0024] Also, manually measuring wear of the drill string components by conventional means can be a part of the preventative maintenance or shift inspection to check and trend wear over time.

[0025] In embodiments of the method the clamping position is achieved by a forcing unit of a table clamp, a breakout table or a breakout fork or any similar unit for holding a first component of a drill string, the forcing unit being movable in a direction orthogonal to the axial extension of the drill string to clamp the first component of the drill string against a support surface.

[0026] This is advantageous as it allows the method to be performed without installation of additional features to the drill, except possibly for a position sensor, which may or may not be included in conventional drill rigs.

[0027] In embodiments of the method the first wear condition of the first component is related to a diameter of the first component.

[0028] In embodiments of the method, it further comprises a step of changing the components of the drill string.

[0029] In embodiments of the method the method further comprises a step of controlling a bailing velocity in response to the determined wear condition. In embodiments of the method, it further comprises a step of controlling a percussive force or rotary force in response to the determined wear condition.

[0030] According to a second aspect the invention relates to a wear monitoring system for performing the process of monitoring wear of the components of the drill string in the method described above, the monitoring system comprising: a forcing unit, and a position sensor configured to detect a position of the forcing unit, a processing unit arranged to receive and process data from the position sensor, and a memory (121) arranged to store the data.

[0031] The data from the position sensor may be position sensor values indicating the trend of wear of a drill string component. The processing unit receives and processes the data from the position sensor. A wear condition of the drill string component can subsequently be determined based on the data from the position sensor. If the determined wear condition exceeds a first wear condition guideline value, or if the determined wear condition diverges from a second wear condition guideline value by more than a threshold margin, the drill string component should be exchanged.

[0032] The processing unit may also be arranged to calculate the displacement of the forcing unit based on the detected position, and optionally calculate a diameter of the first component.

[0033] The monitoring system may further comprise a means for displaying and / or communicating the information to the operator, service person and other office personal.

[0034] In embodiments of the system the forcing unit is part of a clamping table also comprising a support surface and, optionally, a breakout wrench adapted to break a joint between two components of a drill string by rotating a second component when a first component is clamped between the forcing unit and the support surface.

[0035] In embodiments of the system the forcing unit is part of a breakout fork and comprises a wrench portion configured to hold a portion of a drill string component, and wherein the wrench portion is forced into contact with the first component when the clamping position of the forcing unit is determined. According to a second aspect the invention relates to a drill rig comprising the wear monitoring system as defined above.

[0036] The invention also relates to a method performed by a control unit, or a computer connected to the control unit, for controlling the operation of the drill rig described above, wherein the method comprises actions of obtaining data from the position sensor, controlling operation of the forcing unit, and monitoring wear of the drill string component based on the data from the position sensor.

[0037] The method for controlling the operation of the drill rig described above may further comprise, in response to a wear condition of the drill string component, an action of controlling a bailing velocity or an amount of air flow used in the operation of the drill rig.

[0038] Further, the invention relates to a computer program product comprising instructions which, when executed on at least one processor, cause the at least one processor to carry out the method of operating a drill rig as described above.

[0039] Finally, the invention relates to a computer-readable storage medium storing a computer program product comprising instructions which, when executed on at least one processor, cause the at least one processor to carry out the method performed by a control unit as described above.

[0040] Other embodiments of the invention according to the three aspects and advantages thereof will be apparent from the detailed description and the appended drawings.

[0041] BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Below, specific embodiments of the invention will be described with reference to the appended drawings, of which:

[0043] Fig. 1a is a schematic view of a surface drill rig,

[0044] Fig. 1 b is a schematic view of a DTH drill rig,

[0045] Fig. 1c is a schematic view of a drill rig,

[0046] Fig. 2 shows a block diagram representing a method of monitoring wear of components of a drill string, Fig. 3 shows a clamping device in the form of a breakout tool,

[0047] Fig. 4 shows a clamping device in the form of a breakout fork,

[0048] Fig. 5a shows a clamping device in the form of a table clamp with a breakout wrench, and

[0049] Fig. 5b shows a clamping device in the form of a table clamp.

[0050] DETAILED DESCRIPTION OF THE SHOWN EMBODIMENTS

[0051] Embodiments of the present invention will be exemplified in the following in view of two particular kinds of drill rigs, where drilling is carried out through the use of a drilling machine consisting of or comprising a rotation motor, to rotate the drill string during drilling. In the embodiment shown in Fig 1a, the drilling machine 109 also includes a percussion unit, whereas in the embodiment shown Fig 1 b the drill rig comprises a down-the-hole (DTH) / in-the-hole (ITH) hammer 105 providing the percussion inside the drill hole.

[0052] The invention is, however, applicable also for other kinds of drill rigs (Fig. 1c).

[0053] In Fig 1a, the drilling machine 109 is arranged at the end of the drill string 107 on a carriage 104 of a feed beam 103, and the drilling machine 109 forms an integrated unit providing both percussion and rotation.

[0054] Fig. 1a illustrates a rock drilling rig 100 according to an exemplary embodiment of the present invention for which an inventive method of operating a drill rig will be described. The drill rig 100 is in the process of drilling a hole, where the drilling currently has reached a depth x.

[0055] The rock drilling rig 100 according to the present example constitutes a surface drill rig, although it is to be understood that the drill rig may also be of a type being primarily intended e.g., for underground drilling, or a drill rig for any other use. The rock drilling rig 100 comprises a carrier 101 , which carries a boom 102 in a conventional manner. Furthermore, a feed beam 103 is attached to the boom 102. The feed beam 103 carries a carriage 104, which is slidably arranged along the feed beam 103 to allow the carriage 104 to run along the feed beam 103. The carriage 104, in turn, carries a drilling machine 109 comprising a rotation unit and optionally a percussion device, where the rotation is indicated by arrow 117. The drilling machine 109 is connected to a drill bit 106 by means of a drill string 107. The drilling machine 109 may provide rotation in both directions of rotation. The drilling machine 109 may hence run along the feed beam 103 by the sliding carriage 104. The drilling machine 109, in addition to rotating the drill string 107, also provides a feed force acting on the drill string 107 to thereby press the drill bit 106 against the rock face being drilled.

[0056] The drill string 107 may consist of a single drill rod that is threaded to the drilling machine 109. Often, however, the drill string 107 does not merely consist of a drill string in one piece, but, instead, of a number of drill rods that are joined to each other. When drilling has progressed a distance corresponding to a drill rod length, a new drill rod is threaded together with the one or more drill rods that already has been threaded together to form the drill string, whereby drilling can progress for another drill rod length before a new drill rod is threaded together with existing drill rods. Drill rods of the disclosed kind may be extended essentially to any desired length as the drilling progresses. This is illustrated by drill rods 131-133, which are joined to each other by threaded joints 135, 136. It is to be noted that the invention is applicable to drill strings having any number of joints. The drill bit 106 is threaded to the outermost drill rod 133 by means of a threaded joint 137.

[0057] In the shown embodiment in Fig. 1a the drill bit 106 is attached to the drill string 107 via a bit sub 138. A bit sub 138 is needed when the connection mechanism for the drill bit is different from that of the joints 134-137 of the drill pipes 131-133.

[0058] In operation, the percussion unit of the drilling machine 109 repeatedly strikes the drill bit 106 via the drill string 107 in order to transfer shock wave energy into the rock for breaking thereof. The drilling machine 109 also provides rotation of the drill string 107 during drilling to ensure that drill bit inserts of the drill bit 106 are indexed between strokes of the percussion piston to avoid the drill bit inserts from repeatedly striking the rock in the same manner.

[0059] According to the example illustrated in Fig. 1a, the drilling machine 109 is powered by pressurised hydraulic fluid being supplied to the percussion device by one or more hydraulic pumps 116 arranged on the carrier 101 and suitable hosing 118. The carrier 101 also comprises a hydraulic fluid tank 119 from which hydraulic fluid is taken and returned to using the hydraulic circuit powering the drilling machine 109. There may be further hydraulic pumps being used to provide pressurised hydraulic fluid in one or more additional hydraulic circuits, such as e.g., a damping circuit. The invention is applicable for drill rigs comprising hydraulically driven drilling machines, but also for drilling machines operated by electrical or pneumatical means.

[0060] The hydraulic pumps 116, compressor 110 and other power consumers such as e.g., further compressors and further hydraulic pumps are driven by a power source 111 , for example in the form of a combustion engine such as a diesel engine or any other suitable power source, such as e.g. an electric motor, or combination of power sources. Fig. 1a also illustrates a pressure sensor 112 being used to measure the pressure of the hydraulic circuit powering the drilling machine 109. It is to be understood that various other pressure sensors, and also other types of sensors are utilised in connection with drill rigs of the disclosed examples. Such sensors are not illustrated for reasons of simplicity.

[0061] The rock drilling rig 100 further comprises a rig control system comprising at least one control unit 120. The control unit 120 is configured to control various of the functions of the drill rig 100, such as controlling the drilling process. In case the drill rig 100 is manually operated, the control unit 120 may receive control signals from the operator by operator controllable means such as joysticks and other means in an operator cabin 114 requesting various actions to be taken, and where the control signals, such as operator inflicted joystick deflections and / or manoeuvring of other means, may be translated by the control system to suitable control commands. The control unit 120 may, for example, be configured to request motions to be carried out by various actuators such as cylinders / motors / pumps etc., e.g. for manoeuvring boom 102, feeder 103 and controlling the percussion device 105 and drilling machine 109, and various other functions. The described controlling, as well as other functions, may alternatively be partly or fully autonomously controlled by the control unit 120. Also, a memory is arranged in or in connection to the control unit 120 to store relevant data concerning the operation and components of the drill rig.

[0062] Drill rigs of the disclosed kind may also comprise more than one control unit 120, e.g. a plurality of control units, where each control unit, respectively, may be arranged to be responsible for monitoring and carrying out various functions of the drill rig 100. For reasons of simplicity, however, it will be assumed in the following that the various functions are controlled by the control unit 120. Such control systems may further utilise any suitable kind of data bus to allow communication between various units of the drill rig 100. In case the drill rig 100 is manoeuvred by an operator, various data may be displayed e.g. on one or more displays in the operator cabin 114.

[0063] In Fig. 1b an alternative drill rig 100 is shown, wherein the drilling machine 109 is a rotation unit that is connected to a percussion device in the form of a down-the-hole (DTH) hammer 105 via the drill string 107. The rotation unit 109 may provide rotation in both directions of rotation. The rotation unit 109 may hence run along the feed beam 103 by sliding the carriage 104. The rotation unit 109, in addition to rotating the drill string 107, also provides a feed force acting on the drill string 107 to thereby press the drill bit 108 against the rock face being drilled. Furthermore, the hammer 105 comprises a percussive element in the form of a percussion piston acting on the drill bit 106.

[0064] As the name implies, the DTH hammer (percussion device) 105 works down the hole at the end of the drill string 107, where an impact piston (not shown) of the DTH hammer 105 strikes a drill tool to transfer shock wave energy to the drill bit 106 and further into the rock for breaking thereof. DTH hammers are useful, inter alia, in that the drilling rate is not considerably affected by the length / depth of the hole being drilled. The rotation provided by the rotation unit 109 hence transmits the rotation to the hammer 105, and thereby to drill bit 106, via the drill string 107.

[0065] In Fig. 1c yet another drill rig 100 is shown, the drill rig 100 comprising a tower 10 and a platform 20 supporting the tower 10. The drilling machine 109 is arranged on the tower 10. The drilling machine 109 comprises a rotation unit providing axial or rotation force for rotary drilling.

[0066] Regardless of the type of the drill rig 100, the attaching and loosening of the joints between different parts of the drill string may be partly or fully performed by a control unit 120.

[0067] With regards to loosening of the joints, the drill rig 100 further comprises a joint loosening mechanism, schematically indicated by 140 in Figs. 1a, 1b and 1c, of which specific embodiments will be described more in detail below with reference to Fig. 3, Fig. 4, and Fig. 5, respectively.

[0068] As was discussed above, when the drilling of a hole is finished, the drill rod is retracted from the drilled hole where, during the retraction, the components forming the drill string are loosened from each other as the drill string is being pulled out. Similarly, when the length of a rod has been drilled, the rotation unit of the drilling machine 109 is loosened from a joint 134 of the drill rod 131 that has just been drilled so that a further drill rod may be added to the drill string 107.

[0069] The joint breakup mechanism 140 is called breakout tool in the present description, but may, as discussed, also have various other denominations and be of various designs.

[0070] An exemplary clamping device 300 in the form of a breakout tool is illustrated in fig. 3. As mentioned above, the clamping device is also schematically illustrated in Figs. 1a, 1 b and 1c, denoted by 140. The clamping device 300 of fig. 3 is intended for illustrative purposes only, and it is to be realized that the joint loosening mechanism may be of various different designs and configurations. However, common for such designs and configurations of the joint loosening mechanism is that it is provided with means to be pushed against the drill string and hold a component of the drill string still. A break tool further comprises rotating device arranged to provide a torque to another component of the drill string still by means of a lever action to separate or join the two components.

[0071] According to the exemplary embodiment of fig. 3, the clamping device 300 comprises clamping units 302, 303, 304, 305 for clamping parts of the drill string by forcing the part of the part of the drill string. The lower clamping units 304, 305 are utilized to clamp the drill string on one side of the joint to be loosened, and hence one of the drill string components being connected by the joint, whereas upper clamping units 302, 303 are used to clamp the drill string on the other (upper) side of the joint, and hence the other of the drill string components being connected by the joint, to be loosened. Each of the clamping units 302- 305 comprises a forcing unit 306, typically in the form of a jaw. It is to be noted that only the forcing unit 306 of clamping element 303 is visible in the figure. The forcing units 306 grips the drill string components by friction when being pressed against the drill rod, where the needed force may be applied by means of a hydraulic cylinder situated in the housing of the clamping units 303, respectively. The hydraulic cylinder of a clamping units selectively presses the forcing units 306 against the drill string or releases the grip of the drill string as illustrated by arrows 307. Opposite to the shown forcing unit 306 is a support surface 308, which in this embodiment is also a movable forcing unit.

[0072] The shown clamping units work in pairs, respectively, for clamping the drill string from opposite sides of the joint. That is, the upper clamping units 302, 303 clamp the drill string on one side of the joint, and hence one of the drill string components that are to be loosened from another, by being operated in unison to provide a frictional grip of the drill rod to prevent the drill string from being rotated in relation to the jaws of the clamping units. Similarly, clamping units 304, 305 clamp the drill string on the other side of the joint and hence the other of the drill string components that are to be loosened from each other.

[0073] In addition to clamping the drill string by means of the clamping units 302-305, it is also ensured that a break stroke cylinder 310 is in a correct position for performing a break stroke. In general, the break stroke cylinder 310 is set to the correct position prior to clamping the drill string by means of the clamping units 302, 303 which, participate in the joint loosening stroke (also known as a break stroke).

[0074] Further, in connection to the invention, at least one of the clamping units 302-305, or one in each pair of clamping units, or each of the of clamping units 302-305 may be provided with a position sensor 30 arranged to register a position of the related forcing unit 306 of the clamping unit.

[0075] In accordance with the invention the position sensor 30 or sensors may be utilised in a process of monitoring wear of different components of the drill string 107.

[0076] An alternative embodiment of a clamping device 400 is shown in Fig. 4, in which the clamping device comprises a forcing unit 401 in the form of a breakout fork. A breakout fork is adapted to interact with planar recesses in specific parts of the drill string to lock the drill string from rotation, for example when a drill pipe is to be added to or removed from the drill string.

[0077] A position sensor 403 may be arranged to register a position of the forcing unit 401 . Typically, such a position sensor 403 may be arranged to confirm that the forcing unit 401 reaches a correct clamping position in which it clamps the drill string part correctly. Also, a second sensor 404 may be arranged at a support surface 402 to verify that the clamped part is correctly pushed towards the support surface 402.

[0078] According to a specific embodiment, the position sensor 403 may be arranged to register a position of the related forcing unit 401 of the clamping device 400.

[0079] In Figs. 5a and 5b another embodiment of a clamping device 500 is shown. This type of clamping device is often referred to as a table clamp. A table clamp has about the same function as a breakout fork and is hence adapted to clamp a part of a drill string, typically a drill pipe, for example when a drill pipe is to be added to or removed from the drill string. However, in contrast to the breakout fork, the forcing unit 501 of the table clamp is arranged to force the component of the drill string against a support surface 502 instead of, as in the breakout tool, to provide a positive locking of the component.

[0080] A position sensor 503 may be arranged at some location in which it may register a position of the forcing unit 501. Typically, such a position sensor 503 may conventionally be arranged to confirm that the forcing unit 501 reaches a correct clamping position in which it clamps the drill string part correctly. Also, a sensor (not illustrated) may also be arranged to verify that the clamped part is pushed towards the support surface 502 with a sufficiently high force.

[0081] In accordance with a specific embodiment of the invention, the position sensor 503 may be arranged to register a position of the related forcing unit 501 of the clamping device 500. Also shown in Fig. 5a is a separate breakout wrench 504 adapted to provide the extra power needed to break a joint between two parts of a drill string. The function of a breakout wrench is well known to a person skilled in the art and will therefore not be described in detail here. In general, its function corresponds to the function of the breakout tool 300 in Fig. 3, wherein in this embodiment the forcing unit 501 is arranged to hold one part of the drill string as the breakout wrench 504 is utilised to grip and loosen an adjacent part of the drill string.

[0082] In all of the shown embodiment there is hence a forcing unit 301 , 401 , 501 arranged to be pushed against a drill string component, and in correspondence to the invention there is a position sensor 302, 402, 502 arranged to register a position of the related forcing unit of the clamping device. As stated above the position sensor may be utilised in a process of monitoring wear of different components of the drill string.

[0083] The process of monitoring wear of the different components of the drill string 107 is schematically illustrated in the block diagram of Fig. 2.

[0084] A first step of the process, which is not necessarily a first step in a chronological sense, is comprised of identifying 201 a first component of the drill string 107.

[0085] The identifying of the first component of the drill string may be achieved manually by the operator, by an operator at the drill rig, or by some sort of identification means arranged on the drill rig at or close to the forcing unit. For example, the components of the drill string may be provided with an optically readable identification, or an RFID or any other identifiable tag, such that a reader or transmitter located close to the forcing unit may be arranged to identify the identity of the component in conjunction to the determination of the wear of the identified component.

[0086] This first component may for example be a drill bit 106, a drill pipe 132, 133, a deck bushing 30, a bit sub 138, a roller stabiliser (not shown), or a hammer 105.

[0087] A second step of the process consists of moving 202 a forcing unit 306, 401 , 501 into a clamping position P in which it forces the first component against a support surface 308, 402, 502.

[0088] When the forcing unit 306, 401 , 501 is in a clamping position P in which it forces the first component against a support surface 308, 402, 502, the clamping position P of the forcing unit 301 , 401 , 501 is determined in step 203. Based on this determined clamping position P a wear condition WC of the first component is registered in step 204.

[0089] In a subsequent step 205 it is determined if the first wear condition WCi exceeds a first wear condition guideline value WCi, or if the determined wear condition WCi diverges from a second wear condition guideline value WC2 by more than a threshold margin MTH.

[0090] The first wear condition guideline value WC1 corresponds to a wear condition which may be set to indicate that the first component 105, 106, 132, 133, 135 should be exchanged.

[0091] Specifically, the first wear condition guideline value WCi may correspond to a critical diameter of the first component below which the risk of fracture may exceed an acceptable probability.

[0092] The second wear condition guideline value WC2 may corresponds to a historic wear condition of the first component 105, 106, 132, 133, 135, wherein the threshold margin MTH is set to indicate that a periodic wear between the determined wear condition WC and the historic registration, i.e. , the second wear condition guideline value WC2 is outside a range of an acceptable periodic wear.

[0093] The clamping position P may be determined each time the first component 105, 106, 132, 133, 135 is connected to and / or removed from the drill string 107, wherein a corresponding wear condition WC may be registered, manually or automatically, each time the clamping position P is determined to provide a representation over time of the wear of the first component of the drill string 107.

[0094] The clamping position P may also be manually or automatically determined in a periodic fashion. The clamping position P may also be manually or automatically determined during other manual or automated operations, or as a part of a preventative maintenance or shift inspection.

[0095] The process of monitoring wear of components of a drill string as disclosed herein may be combined with other manual or automatic operations for handling the drill string components performed by other devices, such as a bit changer. This has advantages of monitoring wear of the components in the drill string while the bit changer is in operation.

[0096] The clamping position P is achieved by a forcing unit that is movable in a direction D1 that is orthogonal to the axial extension A1 of the drill string 107 to clamp the first component 105, 106, 132, 133, 135 of the drill string 107 against a support surface 308, 402, 502 by means of a forcing unit 306, 401 , 501 . Hence, the clamping position P may be achieved by any of the clamping devices as illustrated in Figs. 3-5 or any other clamping device with a forcing unit movable orthogonally to the axial extension A1 of the drill string 107. It may hence for example be a breakout wrench 300, a breakout fork 400, or a table clamp 500.

[0097] The determined wear condition WC of the first component 105, 106, 132, 133, 135 may be related to a diameter of the first component and correspond the distance between the forcing unit and the opposed support surface. In other words, by determining clamping positions of the forcing unit when clamping first a component 105, 106, 132, 133, 135 over time it will be possible to indirectly monitor the wear related to the diameter of the first component 105, 106, 132, 133, 135.

[0098] Also, with the monitoring of the determined wear condition WC it will be possible to indicate when it is time to changing any of monitored components 105, 106, 132, 133, 135 of the drill string 107.

[0099] Specifically, for the drill pipes or other drill string components, an area moment of inertia may be calculated based on the annular cross section of the drill pipe and from this the column strength of each drill pipe or drill string component may be calculated.

[0100] The allowable load F on the drill string may be calculated from the following formula:

[0101] (1) F = n n2E I / L2where

[0102] F = allowable load (N) n = factor accounting for the end conditions

[0103] E = modulus of elasticity (Pa (N / m2))

[0104] L = length of column (m)

[0105] I = Moment of inertia (m4)

[0106] The moment of inertia I may be calculated from the following formula: where dj = drill pipe inside diameter d0= drill pipe outside diameter This above-mentioned information about a drill string may be provided to an operator or a drill control unit to manually or automatically control the maximum axial force used in the drilling process.

[0107] A person skilled in the art will know how to set the factor accounting for the end conditions n in order to calculate when the drill pipe, or other part of the drill string, needs to be replaced.

[0108] During drilling, air and / or water is provided to clean the drill hole from drill cuttings. The speed at which air travels out of the drill hole through the space between the drill string and the wall of the drill hole is known as bailing velocity. The bailing velocity should be kept at or close to a target value to optimise the drilling operation. To do this, the volume or amount of air flow needs to be adapted to the width of the drill hole, and specifically to the annular cross-sectional area defined by the space between the drill string and the wall of the drill hole. Specifically, to maintain the bailing velocity, the volume or amount of air flow needs to be higher the greater this annular cross-sectional area is.

[0109] The drill hole diameter corresponds to the diameter of the drill bit and is therefore a known, or at least measurable, parameter. Specifically, the wear of the drill bit 106 may be monitored by means of the inventive method and, consequently, the diameter of the drill bit 106 may be monitored. From the diameter of the drill bit 106 the diameter of the drill hole may be deducted.

[0110] Further, by the monitoring of the wear of the remaining parts of the drill string, most importantly the drill pipes which constitute a major part of the drill string, a mean diameter of the drill string may be calculated, such that a mean value of the annulus cross-sectional area between the drill string and the wall of the drill hole may be calculated.

[0111] The calculated the cross-sectional area may, as a further step of the method, be used to control the bailing velocity by regulating the volume or amount of air flow in response to the calculated mean cross-sectional area. This information can be provided to an operator or a drill control unit to manually or automatically optimize the volume or amount of air flow used in the drilling process.

[0112] Above, the invention has been described with reference to specific embodiments. The invention is however not limited to these embodiments. It is obvious to a person skilled in the art that other embodiments are possible within the scope of the following claims.

Claims

CLAIMS1. A method of operating a drill rig (100), the method comprising a process of monitoring wear of components (105, 106, 132, 133, 135) of a drill string (107), which process comprises:- identifying (201) a first component (105, 106, 132, 133, 135) of the drill string (107),- moving (202) a forcing unit (306, 401 , 501) into a clamping position (P) in which the forcing unit (306, 401 , 501) forces the first component (105, 106, 132, 133, 135) against a support surface (308, 402, 502),- determining (203) the clamping position (P) of the forcing unit (306, 401 , 501) by means of a position sensor (305, 403, 503),- determining (204) a wear condition (WC) of the first component (105, 106, 132, 133, 135) based on the determined clamping position (P),- determining (205) if the determined wear condition (WC) exceeds a first wear condition guideline value (WCi), or if the determined wear condition (WC) diverges from a second wear condition guideline value (WC2) by more than a threshold margin (MTH).

2. The method according to claim 1 , wherein the first wear condition guideline value (WC1) corresponds to a wear condition set to indicate that the first component (105, 106, 132, 133, 135) should be exchanged.

3. The method according to claim 1 or 2, wherein the second wear condition guideline value (WC2) corresponds to a historic wear condition of the first component (105, 106, 132, 133, 135), and wherein the threshold margin (MTH) is set to indicate that a periodic wear (AW) between the determined wear condition (WC) and the registration of the second wear condition guideline value (WC2) is outside a range of an acceptable periodic wear ( W1).

4. The method according to any one of the preceding claims, wherein the first component of the drill string 107 is:- a drill bit (106)- a drill pipe (132, 133),- a deck bushing (30),- a bit sub (138),- a roller stabiliser (not shown), ora hammer (105).

5. The method according to any one of the preceding claims, wherein the clamping position (P) is determined on a periodic manual or automatic schedule, or each time the first component (105, 106, 132, 133, 135) is connected to and / or removed from the drill string (107), and wherein a corresponding wear condition (WCn) is registered, manually or automatically, each time the clamping position (P) is determined to provide a representation over time of the wear of the first component of the drill string (107).

6. The method according to any one of the preceding claims, wherein the clamping position (P) is achieved by a forcing unit (306, 401 , 501) of a table clamp, a breakout table (10) or a breakout fork (20) for holding a first component (105, 106, 132, 133, 135) of a drill string (107), the forcing unit (306, 401 , 501) being movable in a direction (D1) orthogonal to the axial extension (A1) of the drill string (107) to clamp the first component (105, 106, 132, 133, 135) of the drill string (107) against a support surface (308, 402, 502).

7. The method according to any one of the preceding claims, wherein the first wear condition (WCi) of the first component (105, 106, 132, 133, 135) is related to a diameter of the first component (105, 106, 132, 133, 135).

8. The method according to any one of the preceding claims, wherein the method further comprises a step of changing the components (105, 106, 132, 133, 135) of the drill string (107).

9. The method according to any one of the preceding claims, wherein the method further comprises a step of controlling a bailing velocity in response to the determined wear condition (WC).

10. The method according to any one of the preceding claims, wherein the method further comprises a step of controlling an axial force or rotary force in response to the determined wear condition (WC).

11. A wear monitoring system for performing the process of monitoring wear of the components (105, 106, 132, 133, 135) of the drill string (107) in the method according any one of the preceding claims 1-10, the monitoring system comprising:- a forcing unit (306, 401 , 501),- a position sensor (305, 403, 503) configured to detect a position of the forcing unit (306, 401 , 501),- a processing unit (120) arranged to receive and process data from the position sensor (305, 403, 503), and- a memory (121) arranged to store the data.

12. The wear monitoring system according to claim 11 wherein the forcing unit (501) is part of a clamping table (500) also comprising a support surface (502) and, optionally, a breakout wrench (504) adapted to break a joint between two components of a drill string by rotating a second component when a first component is clamped between the forcing unit (501) and the support surface (502).

13. The wear monitoring system according to claim 11 wherein the forcing unit (401) is part of a breakout fork (400) and comprises a wrench portion (405) configured to hold a portion of a drill string component, and wherein the wrench portion (405) is forced into contact with the first component (105, 106, 132, 133, 135) when the clamping position (P) of the forcing unit (401) is determined.

14. A drill rig (100) comprising the wear monitoring system according to any one of the claims 11-13.

15. A method performed by a control unit (120), or a computer connected to the control unit (120), for controlling an operation of the drill rig (100) according to claim 14, wherein the method comprises actions of obtaining data from the position sensor (305, 403, 503), controlling operation of the forcing unit (306, 401 , 501), and monitoring wear of the drill string component based on the data from the position sensor (305, 403, 503).

16. The method according to claim 15, further comprising, in response to a wear condition of the drill string component, an action of controlling a bailing velocity or an amount of air flow used in the operation of the drill rig (100).

17. A computer program product comprising instructions which, when executed on at least one processor (120), cause the at least one processor (120) to carry out the method according to claim 15 or 16.

18. A computer-readable storage medium storing a computer program product comprising instructions which, when executed on at least one processor (120), cause the at least one processor (120) to carry out the method according to claim 15 or 16.

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