BR112020011985B1 - SENSOR ELEMENT FOR INDIRECT MONITORING OF CUMULATIVE DAMAGE TO DOWNWELL COMPONENTS AND MONITORING SYSTEM - Google Patents

Abstract

Systems and sensor elements for the indirect monitoring of cumulative damage to downhole components have a sensor body defining an internal cavity, at least one electrical wear element located within the sensor body, a portion of which of the at least one electrical wear member electrically extending from the inner cavity, through the sensor body, and to an exterior of the sensor body, and an abrasive substance situated within the inner cavity, the abrasive substance movable within the inner cavity to contact and erode material of the at least one electrical wear element, wherein erosion of the at least one electrical wear element causes a resistance of the at least one electrical wear element to increase.

Description

CROSS-REFERENCE TO RELATED DEPOSIT ORDERS

[001] This application claims the benefit of US Application No. 15/843193, filed on December 15, 2017, which is incorporated into the present invention, by reference, in its entirety.

BACKGROUND 1. Field of invention

[002] The present invention relates, in general, to downhole components and sensors to monitor environmental damage of downhole components.

2. Description of related technique

[003] Unfinished wells are drilled deep into the earth for many applications such as carbon dioxide sequestration, geothermal production, and hydrocarbon exploration and production. In all applications, exploration wells are drilled so that they pass through or allow access to a material (eg, a gas or fluid) contained in a formation located below the earth's surface. Different types of tools and instruments can be placed in the unfinished pits to perform various tasks and measurements.

[004] In operation, downhole components may be subject to vibrations and various temperatures that can cause wear, fatigue and/or failure of such components. Furthermore, the combination of high temperatures and vibrations can work synergistically to do more damage than either of them alone. Thus, it is advantageous to provide monitoring of such downhole components to determine if the components are approaching a critical amount of wear.

SUMMARY

[005] Systems and sensor elements are disclosed in the present invention for the indirect monitoring of cumulative damage in downhole components that have a sensor body defining an internal cavity, at least one electrical wear element located within the sensor body , wherein a portion of the at least one electrical wear member electrically extends from the inner cavity, through the sensor body, and to an exterior of the sensor body, and an abrasive substance located within the inner cavity, the abrasive substance movable within the internal cavity for contacting and eroding material of the at least one electrical wear element, wherein erosion of the at least one electrical wear element causes a resistance of the at least one electrical wear element to increase.

BRIEF DESCRIPTION OF THE DRAWINGS

[006] The subject, which is considered as the invention, is particularly described and distinctly claimed in the claims at the end of this specification. The foregoing and other features and advantages of the invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings, similar elements being similarly numbered, in which:

[007] Figure 1 is an example of a system for performing downhole operations that may employ embodiments of the present disclosure;

[008] Figure 2 depicts a system for stimulating hydrocarbon formation and production that may incorporate embodiments of the present disclosure;

[009] Figure 3 is a schematic illustration of a monitoring system according to an embodiment of the present disclosure;

[0010] Figure 4 is a schematic partial cut-away illustration of a sensing element according to an embodiment of the present disclosure;

[0011] Figure 5A is a schematic illustration of a sensor element according to an embodiment of the present disclosure; It is

[0012] Figure 5B is a schematic illustration of some components of the sensor element of Figure 5A.

DETAILED DESCRIPTION

[0013] Figure 1 shows a schematic diagram of a system for performing downhole operations. As shown, the system is a drilling system 10 that includes a drill string 20 that has a drill assembly 90, also called a "bottom hole assembly" ("BHA"), carried in a well drilling rig 26 that penetrates an earth formation 60. The drilling system 10 includes a conventional drilling rig 11 erected on a floor 12 that supports a turntable 14 that is rotated by a drive unit such as an electric motor (not shown ), at a desired rotational speed. The drill string 20 includes a drill pipe 22, such as a drill pipe, that extends down from the turntable 14 and into the well 26. A blast tool 50, such as a drill bit attached to the end of the BHA 90, disintegrates the geological formations when it is rotated to drill the exploration well 26. The drill string 20 is coupled to surface equipment, such as systems for lifting, rotating and/or pushing, including, but not limited to a, a winch 30 through a kelly joint 21, injection head 28 and cable 29 through a pulley 23. In some embodiments, the surface equipment may include a top drive (not shown). During drilling operations, the winch 30 is operated to control the weight on the bit, which affects the penetration rate. The operation of winch 30 is well known in the art and will therefore not be described in detail here.

[0014] During drilling operations, a suitable drilling fluid 31 (also called "mud") supplied by a mud source or dike 32 is circulated under pressure through the drill string 20 by a mud pump 34. Drilling fluid 31 passes into the drill string 20 through a pressure surge absorber 36, fluid line 38 and kelly joint 21. Drilling fluid 31 is discharged into the downhole 51 through an opening in the blasting tool 50. Drilling fluid 31 circulates uphole through annulus 27 between drill string 20 and well 26 and returns to mud dike 32 via a return line 35. A sensor S1 in line 38 provides information about fluid flow rate. A surface torque sensor S2 and a sensor S3 associated with the drill string 20 respectively provide information on the torque and rotational speed of the drill string. Additionally, one or more sensors (not shown) associated with the line 29 are used to provide information about the load on the hook of the drill string 20 and about other desired parameters in relation to the drilling of the exploration well 26. The system can additionally include a or more downhole sensors 70 located on the drill string 20 and/or on the BHA 90.

[0015] In some applications, the blasting tool 50 is rotated only by rotating the drilling pipe 22. However, in other applications, a drilling motor 55 (mud engine) disposed in the drilling assembly 90 is used to rotate the blasting tool 50 and/or to superimpose or supplement the rotation of the drill string 20. In both cases, the rate of penetration ("ROP") of the blasting tool 50 into the exploration well 26 for a given Training and a drill set largely depends on the weight on the bit and the speed of rotation of the bit. In one aspect of the embodiment of Figure 1, the slurry motor 55 is coupled to the slurry tool 50 via a drive shaft (not shown) disposed in a bearing assembly 57. The slush motor 55 rotates the slurry tool 50 when drilling fluid 31 passes through mud motor 55 under pressure. The bearing assembly 57 supports the radial and axial forces from the blasting tool 50, the downward thrust from the motor, and the upward reactive load from the weight applied to the bit. Outriggers 58 coupled to bearing assembly 57 and other suitable locations act as centerers for the lowermost portion of the mud motor assembly and other such suitable locations.

[0016] The surface control unit 40 receives signals from the downhole sensors 70 and the devices through a transducer 43, such as a pressure transducer, placed in the fluid line 38, as well as from the sensors S1 , S2, S3, hook load sensors, RPM sensors, torque sensors, and any other sensors used in the system and processes such signals in accordance with programmed instructions supplied to the surface control unit 40. The surface control unit 40 control surface 40 displays desired drilling parameters and other information on a screen/monitor 42 for use by an operator on the drilling rig to control drilling operations. The surface control unit 40 contains a computer, a memory for storing data, computer programs, models and algorithms accessible by a processor in the computer, a recorder such as tape drive, memory unit, etc. to record data and other peripherals. Surface control unit 40 may also include simulation models for use by the computer to process data in accordance with programmed instructions. The control unit responds to user commands entered through a suitable device such as a keyboard. Control unit 40 is adapted to activate alarms 44 when certain unsafe or undesirable operating conditions occur.

[0017] The drill assembly 90 also contains other sensors and devices or tools for providing a variety of measurements regarding the formation surrounding the exploration well and for drilling the exploration well 26 along a desired trajectory. Such devices may include a device for measuring formation resistivity near and/or in front of the drill bit, a gamma ray device for measuring formation gamma ray intensity, and devices for determining the inclination, azimuth and position of the drill string. drilling. A formation resistivity tool 64, produced in accordance with an embodiment described herein, can be attached at any suitable location, including above a lower starting subassembly 62, to estimate or determine formation resistivity near or in front of the formation tool. disintegration 50 or other suitable locations. An inclinometer 74 and a gamma ray device 76 may be suitably placed to respectively determine the slope of the BHA and the formation gamma ray intensity. Any suitable inclinometer and gamma ray device can be used. In addition, an azimuth device (not shown), such as a magnetometer or gyroscopic device, can be used to determine the drill string azimuth. Such devices are known in the art and therefore will not be described in detail in the present invention. In the example configuration described above, the mud motor 55 transfers power to the blast tool 50 through a hollow drive shaft which also allows drilling fluid to pass from the mud motor 55 to the blast tool 50. As an alternative embodiment of the drill string 20, the mud motor 55 can be coupled below the resistivity measuring device 64 or in any other suitable location.

[0018] Still referring to Figure 1, other logging-while-drilling devices ("LWD" - logging-while-drilling) (generally denoted in the present invention by reference number 77), such as devices for measuring formation porosity, permeability , density, rock properties, fluid properties etc. can be placed at suitable locations in the drilling assembly 90 to provide useful information for assessing subsurface formations along the exploration well 26. Such devices may include, but are not limited to, temperature measurement tools, temperature measurement tools, pressure, exploration well diameter measurement tools (eg a gauge), acoustic tools, nuclear tools, nuclear magnetic resonance tools, and formation sampling and testing tools.

[0019] The devices noted above transmit data to a downhole telemetry system 72, which, in turn, transmits the data received uphole to the surface control unit 40. The downhole telemetry system 72 it also receives signals and data from the surface control unit 40 which includes a transmitter and transmits such received signals and data to the appropriate downhole devices. In one aspect, a mud pulse telemetry system can be used for data communication between downhole sensors 70 and devices and surface equipment during drilling operations. A transducer 43 placed in the mud feed line 38 detects mud pulses responsive to data transmitted by downhole telemetry 72. The transducer 43 generates electrical signals in response to mud pressure variations and transmits such signals through a conductor 45 to the surface control unit 40. In other respects, any other suitable telemetry system may be used for two-way data communication (e.g., downlink and uplink) between the surface and the BHA 90, including, but not limited to but limited to, an acoustic telemetry system, an electromagnetic telemetry system, an optical telemetry system, or a wired pipe telemetry system that may use wireless couplers or repeaters on the drill string or downhole. Hardwired piping can be composed by joining sections of drill pipe together, where each pipe section includes a data communication link that runs along the length of the pipe. The data connection between piping sections may be made by any suitable method including, but not limited to, electrical wired or optical connections, induction, capacitive, resonant coupling or directional coupling methods. In the case where a coiled tube (coiled tubing) is used as the drill pipe 22, the data communication link can run along one side of the coiled tube.

[0020] The drilling system described so far refers to those drilling systems that use a drilling pipe to transport the drilling set 90 to the exploration well 26, in which the weight on the bit is controlled from the surface, typically by controlling the winch operation. However, a large number of today's drilling systems, especially for drilling highly deviated and horizontal exploration wells, use coiled tubing to transport the drill rig downhole. In such an application, a propeller is sometimes installed in the drillstring to provide the desired force on the drill bit. Furthermore, when coiled tubing is used, the tubing is not rotated by a rotary table but is instead injected into the exploration well by a suitable injector, while the downhole engine such as the mud engine 55 , rotates the blasting tool 50. For offshore drilling, an offshore platform or vessel is used to support the drilling equipment, including the drill string.

[0021] Still referring to Figure 1, a resistivity tool 64 can be provided that includes, for example, a plurality of antennas including, for example, transmitters 66a or 66b and/or receivers 68a or 68b. Resistivity can be a formation property that is of interest when making drilling decisions. Those skilled in the art will appreciate that other formation property tools can be employed with or in place of the resistivity tool 64.

[0022] Liner drilling can be a setup or operation used to provide a blasting device that is becoming more and more attractive in the oil and gas industry as it has several advantages compared to conventional drilling. An example of this configuration is shown and described in commonly owned US Patent No. 9,004,195 entitled "Apparatus and Method for Drilling a Borehole, Setting a Liner and Cementing the Borehole During a Single Trip", which is incorporated herein at reference title in its entirety. It is important to note that despite a relatively low penetration rate, the time to get the casing to the target is reduced because the casing is applied to the downhole while the exploration well is drilled simultaneously. This can be beneficial in expansion formations where a downhole drill hole can make a later liner installation difficult. Additionally, liner drilling in depleted and unstable reservoirs minimizes the risk of the pipe or drillstring becoming trapped due to hole collapse.

[0023] Although Figure 1 is shown and described in relation to a drilling operation, those skilled in the art will recognize that similar configurations, albeit with different components, can be used to perform different downhole operations. For example, wire rope, coiled tube and/or other configurations can be used as known in the art. Additionally, production setups can be employed to extract and/or inject materials from/into earth formations. Accordingly, the present disclosure should not be limited to drilling operations, but may be employed for any suitable or desired downhole operation (or operations).

[0024] With reference to Figure 2, there is shown a schematic illustration of one embodiment of a system 100 for producing hydrocarbons and/or evaluating an earth formation 102 that may employ embodiments of the present disclosure. System 100 includes an exploration shaft 104 disposed in an exploration shaft 106. The column 104, in one embodiment, includes a plurality of column segments or, in other embodiments, is a continuous conduit such as a coiled tube. As described in the present invention, "pile" refers to any structure or conveyor suitable for lowering a tool or other component through an exploration well or attaching a drill bit to the surface, and is not limited to the structure and configuration described herein. . The term "carrier", as used herein, means any device, device component, combination of devices, means and/or member that can be used to transport, house, support or otherwise facilitate the use of another device, device, combination of devices, means and/or member. Examples of non-limiting carriers include, but are not limited to, casing pipe, wire rope, wire rope rigs, wire rigs, drop explosives, downhole subs, downhole assemblies, and drill strings .

[0025] In one embodiment, the system 100 is configured as a hydraulic stimulation system. As described in the present invention, "stimulation" can include any injection of a fluid into a formation. A fluid can be any flowable substance such as a liquid or gas, or a flowable solid such as sand. In such an embodiment, column 104 includes a downhole assembly 108 that includes one or more tools or components to facilitate stimulation of formation 102. For example, column 104 includes a fluid assembly 110, such as a glove device. fracture or "frac" or electric submersible pumping system and a drill set 112. Examples of the drill set 112 include shaped charges, torches, projectiles and other devices for piercing an exploration well wall and/or casing. Column 104 may also include additional components, such as one or more insulation subs or shutter 114.

[0026] One or more of the downhole assembly 108, the fracturing assembly 110, the drilling assembly 112 and/or the shutter subs 114 may include electronic circuits or suitable processors configured to communicate with a processing unit surface area and/or control the respective tool or assembly.

[0027] A surface system 116 may be provided to extract material (e.g. fluids) from the formation 102 or to inject fluids through the column 104 into the formation 102 for the purpose of fracturing.

[0028] As shown, the surface system 116 includes a pumping device 118 in fluid communication with a tank 120. In some embodiments, the pumping device 118 can be used to extract fluid, such as hydrocarbons, from the formation 102 and store the extracted fluid in tank 120. In other embodiments, pumping device 118 can be configured to inject fluid from tank 120 into column 104 and introduce it into formation 102 to, for example, stimulate and/or fracture formation 102.

[0029] One or more flow rate and/or pressure sensors 122, as shown, are disposed in fluid communication with the pumping device 118 and the column 104 for measuring fluid characteristics. The sensors 122 may be positioned in any suitable location, such as next to (for example at the discharge outlet) or inside the pumping device 118, at or near a wellhead, or at any other location along the column 104 and/or in exploration well 106.

[0030] A processing and/or control unit 124 is arranged in operable communication with the sensors 122, with the pumping device 118 and/or with the components of the downhole assembly 108. The processing and/or control unit 124 is configured to, for example, receive, store and/or transmit data generated from sensors 122 and/or pumping device 118 and includes processing components configured to analyze data from pumping device 118 and sensors 122, provide alerts to the pumping device 118 or other control unit and/or control operating parameters and/or communicate with and/or control components of the downhole assembly 108. The processing and/or control unit 124 includes any number of suitable components such as processors, memory, communication devices, and power supplies.

[0031] Vibration and thermal fatigue of circuit boards, sensors, or other components (hereinafter "downhole components") in downhole systems, as shown and described above, may cause the downhole component well failure, thus requiring maintenance and/or replacement. To reduce the risk of failure, downhole components can be replaced at regular intervals or on a predetermined schedule, which can be much earlier than it is expected for downhole components to actually fail (e.g. preventative maintenance) . However, replacing downhole components prematurely can be costly and, additionally, such replacement may be unnecessary. Thus, there is a need for a simple, passive, robust sensor or other monitoring device to measure a cumulative environmental exposure (eg, vibration exposure, thermal exposure, etc.) that downhole components experience. For example, such sensors as disclosed in the present invention provide a similarly worn sensor to provide indirect monitoring of downhole components and to enable determination of the possibility that the downhole components are approaching a specified amount. wear or critical vibration fatigue.

[0032] Now referring to Figure 3, a schematic illustration of a monitoring system 300 is shown. Monitoring system 300 is disposed on or in a downhole component 302, such as a printed circuit board. Downhole component 302, although shown as a printed circuit board, can be any downhole component that includes wiring, circuitry, and/or other elements that may suffer from wear, fatigue, and/or failure due to environmental and/or operational conditions such as vibrations and/or temperature while located downhole. The downhole component 302, in some embodiments, is disposed as part of a downhole tool that is deployed downhole in a wellbore. For example, in an embodiment without limitation, the downhole component 302 is part of a BHA and provides control and/or electrical function to at least part of the BHA.

[0033] As shown, the downhole component 302 includes one or more electrical elements 304. The electrical elements 304 may be subject to high temperatures and/or vibration during deployment through a well, during drilling, exploration and /or production. In some embodiments, the downhole component 302 is configured to electronically control one or more other components of a column or downhole structure.

[0034] To enable passive in situ monitoring of environmental impacts on the downhole component 302, the monitoring system 300 includes a sensor assembly 306. The sensor assembly 306 is fixedly attached to the downhole component 302 and includes a protective housing 308 that is exposed to an environment to which the downhole component 302 is exposed. The sensor assembly 306 is arranged to monitor cumulative damage or wear that is sensed by the downhole component 302. For example, when the downhole component 302 is disposed downhole, the downhole component 302 will be subject to to vibrations that can wear or damage the elements of the downhole component 302 (for example, the electrical elements 304). Each time the downhole member 302 is disposed downhole, the electrical elements 304 will be subject to such vibrations. The sensor assembly 306 (and sensor elements as described in the present invention) is arranged to provide passive cumulative damage monitoring onboard the downhole component 302.

[0035] The protective housing 308 isolates one or more sensor elements 310, 312. The sensor elements 310, 312 are arranged or configured to be subject to some environmental impacts that are felt by the downhole component 302, however, they are protected or isolated from others, such as high pressure borehole fluid or corrosive or erosive borehole fluids, through protection by the protective casing 308. In some embodiments, the protective casing 308 may be optional or completely absent, depending on the specific configuration of the sensor array that is employed. Furthermore, in some embodiments, the protective housing 308 may be openable, which allows selective access to the interior of the protective housing 308 and components located therein (e.g., sensing elements 310, 312, and associated wiring).

[0036] As shown, the sensor elements 310, 312 are electrically connected to or are part of the respective detection circuits 314, 316 through wiring 318. In some embodiments without limitation, the sensor elements 310, 312 and the respective detection circuits 314, 316 form Wheatstone bridges. One or more of the sensing elements 310, 312 are arranged to sense the various environmental conditions, such as vibration and thermal conditions, that the downhole component 302 is exposed to during operation.

[0037] In an example without limitation, a first sensor element 310 is arranged with electrical wiring running through or on an interior surface of a sensor body, as described in the present invention. The sensor body is a hollow body that defines an internal cavity. The sensor body includes at least one electrical wear element (e.g., a wire) that passes through the internal cavity or is installed along a surface of the internal cavity. In some embodiments, the electrical wear element(s) will pass through the sensor body from an interior to an exterior of the sensor body.

[0038] The inner cavity is at least partially charged with an abrasive substance that is selected to abrade, impact, or otherwise erode the wiring within the inner cavity. Wiring within the inner cavity (or interior wiring) is electrically connected to wiring 318 and detection circuit 314, thus completing a circuit. As the interior wiring is eroded or damaged by the abrasive substance, the electrical conductivity of the interior wiring will decrease (or stop if the interior wiring breaks) which may thus disconnect the detection circuit 314, which in turn may trigger a notification or other alarm that indicates that the 302 downhole component was subject to environmental downhole conditions sufficient to warrant maintenance (eg, inspection, repair, replacement, etc.). In another example without limitation, as an alternative to real-time monitoring, a passive sensor can be measured, verified or otherwise inspected upon return to the surface. The cumulative damage to the electrical elements in the sensor acts as a physical memory which does not require any electrical energy to store or maintain the memory and which is used here in place of the temperature sensitive and/or expensive computer memory which could continuously record readings of accelerometer. Embodiments provided in the present invention can be used to predict a remaining useful life for a monitored system or device, then thereby enable predictive maintenance scheduling and programs. Since interior wiring can be used to represent fatigue in the downhole component 302 and such monitoring must be insulated from other influences, the sensor body can be formed from an electrically insulating material to prevent unwanted electrical connections. .

[0039] The sensor elements 310, 312 operate when exposed to the same conditions as the downhole component 302 to which they are fixedly connected. In this way, when the downhole component 302 vibrates, the sensing elements 310, 312 will also vibrate. Similarly, if the downhole component 302 is exposed to high temperatures that could impact the elements of the downhole component 302 (e.g., wiring, metal parts, circuitry, etc.) the sensing elements 310 , 312 will also be exposed to such temperatures. In some embodiments, the second sensing element 312 can be a control or reference sensing element 312 that does not include an abrasive substance therein, and thus can operate as a test or comparison with the first sensing element 310.

[0040] In an example without limitation of a sensor element of the present disclosure, three-dimensional monitoring of forces or conditions that impact the downhole component to which a sensor assembly is connected or attached is enabled. In order to measure cumulative vibration exposure in three dimensions, each of a geometric axis or X, Y and Z direction may be arranged with three electrical wear elements (e.g. three wires) within the inner cavity of the sensor body , where each of the three wires extend along a respective X axis, Y axis, and Z axis. Erosion is greatest when the mobilized abrasive substance strikes, impacts, or otherwise comes into contact with a electrical wear element perpendicular to the axis of the impacted electrical wear element. Consequently, having electrical wear elements arranged along all three major directions allows distinguishing the damage done by vibration along each direction. Through experimentation, modeling, etc., the properties and characteristics of the abrasive substance (e.g., particle size, hardness, quantity, etc.) and the properties and characteristics of the electrical wear elements (e.g., diameter, thickness, softness) of material, etc.) can be selected to optimally mimic a life degradation of a downhole component that is monitored and to enable accurate estimation of a remaining service life of such downhole component.

[0041] The different interior electrical wear elements, when arranged as wires, may, at various points in time, be connected to a Wheatstone bridge, which may include the electrical wear elements in the reference sensing element 312, so as to sensibly measure any increase in resistance of the interior electrical wear elements that may result from erosion of the interior electrical wear elements. That is, as the abrasive substance interacts with the interior electrical wear elements, the material of the interior electrical wear elements can be removed or abraded, thus reducing the diameter or size of the electrical wear element (or breaking it), which , in turn, will increase the resistance of the elements to electrical wear, which is a measurable characteristic.

[0042] The interior electrical wear elements may be made of an electrically conductive material, which is selected so as to be eroded or abraded by the abrasive substance. For example, the interior wiring can be formed from aluminum. The abrasive substance is a material selected to scratch, cut, abrade, erode, or otherwise reduce the amount of interior wiring material due to impacts of the abrasive substance with the interior electrical wear element. For example, the abrasive substance can be formed from a granulated silicon carbide, which has a Moh's hardness of 9. In another example, industrial diamond coarse meal, which has a Moh's hardness of 10, can be used as a the abrasive substance.

[0043] In some embodiments, a communication device can be electrically connected to the detection circuits 314, 316. If a resistance detected or measured within the detection circuits 314, 316 exceeds a predetermined threshold, a message can be triggered to be sent to a surface operator that the specific downhole component 302 is approaching a maintenance state (e.g., wear on the downhole component 302 is projected to have reached a state in which it needs a maintenance operation ). In other arrangements, a measuring or testing tool may be connected to detection circuitry 314, 316 when the downhole tool 302 is brought to the surface (eg, tripped from a well).

[0044] Now referring to Figure 4, a schematic illustration of a sensor element 400, according to an embodiment of the present disclosure, is shown. Sensor element 400 may be mounted on or otherwise affixed to a downhole component to enable monitoring of wear due to vibrations and/or the temperature to which the downhole component is exposed. Sensor element 400 includes a sensor body 402 defining a hollow internal cavity 404. As shown, sensor body 402 is spherical in shape, although other shapes, configurations, geometries, etc., may be employed without departing from the scope of the present disclosure. The sensor body 402 has a plurality of electrical wear elements passing therethrough, the electrical wear elements extending along the X, Y, and Z axes to enable three-dimensional monitoring. As shown, a first electrical wear element 406 extends along an X axis, a second electrical wear element 408 extends along a Y axis, and a third electrical wear element 410 extends along a Z axis and these three wear elements (eg wires) are slightly offset so that they do not come into contact with each other near the center of the sensor body 402 (eg ball).

[0045] The sensor body 402 is formed from insulating material, so that the only electrical conduction inside or outside the internal cavity 404 is through the electrical wear elements 406, 408, 410 that pass through the sensor body 402. As shown, electrical wear elements 406, 408, 410 pass from the inner cavity 404, through the sensor body 402 and to an outside of the sensor body 402, where such electrical wear elements 406, 408, 410 may be electrically connected to other electrical or accessible elements to be selectively connected.

[0046] For example, the electrical wear elements 406, 408, 410 may each be connected to an independent or dedicated detection circuit, either continuously or on demand. As schematically shown with respect to the second electrical wear element 408, the electrical wear element 408 may optionally pass through an insulated portion 412 of the sensor body 402. The insulated portion 412 may be a plug or other part of the sensor body 402 that is arranged to support the second electrical wear element 408 as it passes the sensor body 402 and may also provide rigid or structural support to prevent the second electrical wear element 408 from breaking at points where the second electrical wear element 408 enters and exits the sensor body 402. In embodiments having the insulating portion 412 of the sensor body 402, the sensor body 402 may be formed of any desirable material, even optionally an electrically conductive material, with the portion insulator 412 electrically insulates and insulates the electrical wear elements 406, 408, 410 at the locations where the electrical wear elements 406, 408, 410 pass through the sensor body 402.

[0047] The internal cavity 404 of the sensor body 402 is at least partially loaded with an abrasive substance 414. The abrasive substance 414 is selected to abrade, impact or otherwise erode the material of the electrical wear elements 406, 408 , 410, such that as the electrical wear elements 406, 408, 410 are impacted by the abrasive substance 414, the material of the electrical wear elements 406, 408, 410 is removed and an electrical resistance is increased (e.g. when tested by a connected detection circuit). The impact of the abrasive substance 414 against the electrical wear elements 406, 408, 410 is caused by movement (e.g., vibrations) of the sensor body 402. As the sensor body 402 vibrates, the abrasive substance 414 will be moved within the cavity. internal 404 of sensor body 402.

[0048] In an example embodiment, the abrasive substance 414 is a particulate or granular material (for example, a coarse flour material) that, as the sensor body 402 is vibrated, the particles of the abrasive substance 414 are pushed and mobilized by shock and vibrations contacting the electrical wear elements 406, 408, 410. As the particles impact the electrical wear elements 406, 408, 410, material from the electrical wear elements 406, 408, 410 will be removed, thus, a resistance of the electrical wear elements 406, 408, 410 is increased, which can be measured using a sensing circuit such as a Wheatstone bridge. Erosion of the material of the electrical wear elements 406, 408, 410 causes the electrical resistance of the electrical wear elements 406, 408, 410 to cumulatively and permanently increase individually or separately. An erosion rate of the electrical wear elements 406, 408, 410 may depend on an angle at which an object (e.g., the electrical wear elements 406, 408, 410) is struck by an object (e.g., the abrasive substance 414). Thus, as shown in the embodiment of Figure 4, the sensing element 400 is arranged to provide separate and cumulative X, Y, and Z axis vibration exposure measurements by having the electrical wear elements 406, 408, 410 as arranged, as shown and described above.

[0049] Those skilled in the art will understand that the number of electrical wear elements installed in a sensing element of the present disclosure is not limited to three, as shown. That is, numerous electrical wear elements can be installed within the sensor bodies of the present disclosure. In some embodiments, a single electrical wear element may be arranged which passes through an internal cavity of a sensor body. In some such embodiments, a unique dimension of wear monitoring may be provided. Furthermore, numerous sensing elements can be installed on one or more downhole components.

[0050] As shown in Figure 4, the electrical wear elements 406, 408, 410 are arranged as wires passing through the sensor element 400 along the respective X, Y and Z axis. , 408, 410 are electrically conductive, and it is desirable to monitor vibration or wear in one direction of each of the respective X, Y, and Z axis, the electrical wear elements 406, 408, 410 are positioned not to come into contact with each other. with each other at a center 416 of the sensing element 400. That is, the electrical wear elements 406, 408, 410 are arranged to be displaced from each other such that no electrical contact occurs between the electrical wear elements 406, 408, 410.

[0051] The abrasive substance of the present disclosure may be particulate matter, a fluid, a combination of fluid and solid (e.g. suspended particulate), a gas or liquid which changes material or phase state depending on temperature, etc. In some embodiments, the abrasive substance will fill less than the entire internal cavity of the sensor body. In an example without limitation, the volume of the inner cavity is 50% filled by the abrasive substance. In another embodiment, such as with particulates suspended in liquid, the entire internal cavity (100%) can be filled with the abrasive liquid suspension. Examples of potential particulate abrasive substances include, but are not limited to, glass, ceramics, steel (e.g., cutting edge, projectile, coarse flour), aluminum oxide, silicon carbide, garnet, diamond, etc. The selection of abrasive substance can be based on the specific material of the electrical wear elements, the amount of volume within the internal cavity of the sensor body, the material used to form the sensor body, or based on other considerations. One consideration is to select an abrasive substance that will erode the electrical wear elements through impact at a predetermined or desired rate that is representative of wear on other electronics of the downhole component to which the sensing element is installed.

[0052] Similarly, the material of the electrical wear elements can be selected by wear properties based on exposure to the abrasive substance, so that the wear of the electrical wear elements mimics or simulates the wear or fatigue of one or more more electronic components, such as circuit boards, from the downhole component to which the sensing element is installed. Thus, the material selection of the abrasive substance and the electrical wear elements can be selected in combination to achieve a desired wear pattern.

[0053] As mentioned, the selection of abrasive substance may include liquids. One purpose for employing a liquid (either as a suspending fluid or to provide abrasion) is to allow for the change in viscosity due to temperature. The change in viscosity can be tailored to mimic the potential for increased vibration damage at higher temperatures. This is possible since the erosion damage of suspended particles will be greater at lower viscosity. In such embodiments, the sensor body may be formed from a material that is thermally conductive yet electrically insulated. In suspension, an example configuration would be to fill the internal cavity with 1-propanol. 1-propanol is a liquid below about 97°C and will boil at atmospheric pressure at about 97°C. If sealed in a fixed volume chamber above 97°C, the gas fraction will continue to increase with temperature and the liquid fraction will continue to decrease with temperature, so more of the abrasive substance will be retarded by the gas less viscous and less of the abrasive substance will be retarded by the more viscous liquid which results in a more abrasive mixture with a temperature dependent abrasive capacity and thus can mimic the greater damage that downhole components experience when heated and vibrated.

[0054] Thus, if such a sensor element is installed in a downhole component and the downhole component is subject to vibrations and different temperatures, the erosion rate of the electrical wear elements may be variable based on the temperature. For example, when the downhole component is located at relatively low temperatures, such as at the surface or in early implantation stages, vibrations may not be as damaging and thus the liquid state of a portion of the abrasive substance will prevent damage from occurring. /excessive erosion occurs on electrical wear elements. However, when the downhole component is located downhole and in operation and subject to high downhole temperatures, more of the liquid portion will evaporate and become gaseous, at which time suspended particles can more effectively impact the elements. electrical wear. Another example of fluid might be 1-butanol, which has a boiling point at atmospheric pressure of approximately 117°C.

[0055] With reference now to Figures 5A to 5B, schematic illustrations of a sensing element 500 according to an embodiment of the present disclosure are shown. In contrast to the embodiment described above with a spherical shaped sensor body, the sensor element 500 has a sensor body 502 that is cubic in shape. The sensor body 502 is formed from a plurality of plates 504. The plates 504 are mounted on a base 506 and may be terminated by a top 508. Each of the plates 504 includes a first portion 510 of an electrical wear element . Similarly, base 506 includes one or more second electrical wear element portions 512, wherein first portions 510 and second portions 512 are electrically connectable to form one or more electrical wear element within sensor body 502. As illustratively shown, a portion of the second portion 512 at the base 506 forms a first directing portion of an electrical wear element, and each of the first portions 510 shown in Figure 5B represent further directing portions, so that a three-dimensional sensing element 500 can be mounted. In some embodiments, all or any of the plates 504, base 506 and/or top 508 may include portions of an electrical wear element.

[0056] The sensing element 500 can be filled with an abrasive substance similar to that described above. In an example without limitation, the sensing element 500, as shown, forms a housing made of ceramic plates that include conductive (e.g., metal portions 510, 512) tracks (e.g., metallic) that form the element(s). s) electrical wear. Portions 510, 512 can be worn by impacts or contact with abrasive substance, similar to that described above. Thus, in some embodiments, the electrical wear member(s) may be "grinding structures" in which the material of portions 510, 512 is worn or chipped, with an increase in strength resulting therefrom. , similar to the wire arrangement described above. Second portions 512 extend to an edge of base 506 and provide electrical connection to a printed circuit board to which sensing element 500 is attached, or provide on-demand connection to a voltmeter, ohmmeter, or other electrical testing device . Although the second portions 512 in Figures 5A to 5B are shown in a specific arrangement, those skilled in the art will understand that the second portions that are located on the base and/or the first portions located on the plates can be in any arrangement or configuration, without depart from the scope of the present disclosure.

[0057] In an example of the sensor element 500 of Figures 5A to 5B, the internal cavity of the cubic sensor element 500 can be filled with a fluid with particles suspended therein, similar to that described above. As will be understood by those skilled in the art in view of the above disclosure, any type of fluid, which includes mineral oils, can be used with a selected evaporation point that is selected for specific temperatures and/or viscosity properties. That is, the fluid can be selected to change phase (eg liquid to gas, supercritical phase change, etc.) at a predetermined temperature.

[0058] For example, in another example using the cubic sensor element 500, the internal cavity can be filled with propane, which has a critical temperature close to 96.7°C, which is approximately the minimum temperature of most wells near the bottom of the well. Plates 504 may be about 10 mm high, and terminated with a top 508. The first portions 510 on plates 504 may be partially submerged with a suspension of fluid that is about 5 mm (i.e., about half the height) of the 504 plates) filled with a coarse flour and about 4 mm of liquid propane column at room temperature contained in the internal cavity. Initially, at room temperature in this example, about 80% of the coarse meal is immersed in the viscous liquid propane and only 20% of the coarse meal is in a low viscosity vapor (ie, above the liquid level within the internal cavity). The 20% that are not underwater will be free to move and the 80% that are underwater will have highly attenuated motion. However, above the critical temperature of 96.7°C, the propane will become supercritical, and so all of the coarse meal will now be located within a supercritical fluid that has a lower viscosity than the liquid (but a higher viscosity than the liquid). propane steam). Although the above description is made with respect to propane, other fluids can be used without departing from the scope of the present disclosure. For example, various non-flammable, non-toxic fluids with a supercritical temperature of approximately 100°C can be employed. Some of such examples might be halocarbon refrigerants (eg R12, R22 and R134a), which are commonly known as Freons.

[0059] Advantageously, modalities provided in the present invention are directed to passive monitoring systems that enable monitoring of wear of downhole components, and such monitoring is performed in situ. Monitoring systems are arranged to enable erosion of electrical wear elements due to environmental conditions such as vibrations and thermal conditions. By eroding the electrical wear elements and testing a resistance on a test device electrically connected to the electrical wear elements, a resistance can be measured as the resistance that represents or indicates an amount of wear of the electrical wear elements. As erosion of electrical wear elements increases, so does resistance when connected to a test circuit such as a Wheatstone bridge.

[0060] Through simulations, testing and observation, it is possible to determine when a specific resistance is measured, that a downhole component was subject to a lot of vibration or other environmental condition. Electrical wear elements and an abrasive substance can be selected to precisely match the specific sensing element with the downhole component that is to be monitored. Various geometric shapes of sensor bodies can be employed to provide different physical properties or to adapt to a specific downhole component to be monitored.

[0061] Modality 1: Sensor element for indirect monitoring of cumulative damage to downhole components, the sensor element comprising: a sensor body defining an internal cavity, at least one electrical wear element located inside the body of the sensor body, wherein a portion of the at least one electrical wear element extends electrically from the inner cavity, through the sensor body, and to an exterior of the sensor body, and an abrasive substance located within the inner cavity, the abrasive substance movable within the inner cavity for contacting and eroding material of the at least one electrical wear element, wherein erosion of the at least one electrical wear element causes a resistance of the at least one electrical wear element to increase .

[0062] Embodiment 2: Sensor element, according to any embodiment in the present invention, in which the at least one electrical wear element is a wire passing through the internal cavity.

[0063] Embodiment 3: Sensor element, according to any embodiment of the present invention, in which the at least one electrical wear element comprises three wires, each wire passing through the internal cavity, one of each of the three wires extends along an X axis, a Y axis, and a Z axis.

[0064] Embodiment 4: Sensor element, according to any embodiment in the present invention, in which the three wires are arranged so that no electrical contact occurs between the three wires.

[0065] Embodiment 5: Sensor element, according to any embodiment in the present invention, in which the sensor body is spherical in shape.

[0066] Embodiment 6: Sensor element, according to any embodiment in the present invention, in which the sensor body is a cubic sensor body.

[0067] Embodiment 7: Sensor element according to any embodiment of the present invention, wherein the sensor body comprises a plurality of plates, wherein at least a first portion of the at least one electrical wear element is formed along an interior surface of at least one of the plurality of plates facing the internal cavity.

[0068] Embodiment 8: Sensor element, according to any embodiment in the present invention, in which the sensor body additionally comprises a base and each of the plurality of plates is mounted on the base to define the sensor body in cubic shape, and wherein a second portion of the at least one electrical wear element is disposed at the base.

[0069] Embodiment 9: Sensor element, according to any embodiment in the present invention, in which the abrasive substance comprises at least one particulate material and gravel.

[0070] Embodiment 10: Sensor element, according to any embodiment of the present invention, in which the abrasive substance comprises a fluid and a particulate material, the particulate material being suspended within the fluid.

[0071] Embodiment 11: Sensor element, according to any embodiment in the present invention, in which the fluid comprises a supercritical fluid.

[0072] Embodiment 12: Sensor element, according to any embodiment in the present invention, in which the fluid is selected to change phase at a predetermined temperature.

[0073] Embodiment 13: Sensor element, according to any embodiment in the present invention, in which the sensor body is formed from a material that is electrically insulating and thermally conductive.

[0074] Embodiment 14: Sensor element, according to any embodiment in the present invention, in which the sensor body is electrically insulating.

[0075] Embodiment 15: Sensor element, according to any embodiment in the present invention, wherein the sensor body comprises an insulated portion, where at least one electrical wear element passes through the sensor body in the insulated portion.

[0076] Embodiment 16: Monitoring system comprising: a downhole component comprising at least one electrical element, the downhole component being arranged as part of a downhole tool for deployment in a well ; and a sensor assembly mounted to the downhole component, the sensor assembly comprising: at least one sensor element having a sensor body defining an internal cavity; at least one electrical wear element located within the sensor body, wherein a portion of the at least one electrical wear element electrically extends from the internal cavity, through the sensor body and to an exterior of the sensor body; and an abrasive substance located within the inner cavity, wherein the abrasive substance is movable within the inner cavity to contact and erode the material of the at least one electrical wear element, wherein erosion of the at least one wear element electrical causes a resistance of the at least one electrical wear element to increase.

[0077] Embodiment 17: Monitoring system, according to any embodiment of the present invention, in which the at least one sensor element comprises a first sensor element and a second sensor element, the first sensor element including the abrasive substance in it and the second sensing element is a reference sensing element that does not contain the abrasive substance therein.

[0078] Embodiment 18: Monitoring system, according to any embodiment of the present invention, which additionally comprises a protective housing, wherein the at least one sensor element is housed within the protective housing.

[0079] Embodiment 19: Monitoring system, according to any embodiment of the present invention, in which the downhole component is a printed circuit board.

[0080] Embodiment 20: Monitoring system, according to any embodiment of the present invention, in which the abrasive substance comprises a fluid and a particulate material, the particulate material being suspended within the fluid.

[0081] In support of the teachings of the present invention, various analysis components can be used including a digital and/or analogue system. For example, controllers, computer processing systems, and/or geological guidance systems, as provided herein and/or used with the embodiments described herein, may include digital and/or analog systems. Systems may have components such as processors, storage media, memory, inputs, outputs, communication links (e.g. wired, wireless, optical or otherwise), user interfaces, software programs, signal processors (e.g. , digital or analog) and other such components (e.g., resistors, capacitors, inductors and the like) to provide operation and analysis of the apparatus and methods disclosed in the present invention in any of a number of ways well understood in the art. It is understood that these teachings may be, but need not be, implemented in combination with a set of computer-executable instructions stored on non-transient computer-readable media, including memory (e.g., ROMs, RAMs), optics (e.g., CD-ROMs), or magnetic (e.g. disks, hard disks), or any other type that, when executed, causes a computer to implement the methods and/or processes described herein. These instructions may provide equipment operation, control, data collection, analysis, and other functions deemed relevant by a systems designer, owner, user, or other personnel, in addition to the functions described in this disclosure. The processed data, as a result of an implemented method, can be transmitted as a signal through a processor output interface to a signal receiving device. The signal receiving device can be a display monitor or printer to present the result to a user. Alternatively or additionally, the signal receiving device can be a memory or a storage medium. It will be noted that storing the result in memory or storage media can transform the memory or storage media into a new state (i.e., containing the result) from an earlier state (i.e., not containing the result). ). Additionally, in some embodiments, an alert signal may be transmitted from the processor to a user interface if the result exceeds a threshold value.

[0082] Additionally, various other components may be included and called upon to provide aspects of the teachings of the present invention. For example, a sensor, transmitter, receiver, transceiver, antenna, controller, optical unit, electrical unit and/or electromechanical unit may be included in support of the various aspects discussed in the present invention or in support of other functions beyond this disclosure.

[0083] The use of the terms "a", "an", "the" and "the" and similar references in the context of describing the invention (especially in the context of the following claims) shall be interpreted as encompassing both the singular and the plural, except where otherwise indicated in the present invention or clearly contradicted by the context. Furthermore, it should be further considered that the terms "first", "second" and the like in the present invention do not denote any order, quantity or importance, but are instead used to distinguish one element from another. The "about" modifier used in connection with a quantity is inclusive of the stated value and has the meaning dictated by the context (for example, it includes the degree of error associated with measuring the specific quantity).

[0084] It will be recognized that the various components or technologies may provide certain necessary or beneficial features or functionality. Accordingly, such functions and features as may be required in support of the appended claims and variations thereof, are recognized as being inherently included as a part of the teachings of the present invention and a part of the present disclosure.

[0085] The teachings of the present disclosure can be used in a variety of well operations. These operations may involve the use of one or more treatment agents to treat a formation, the resident fluids in a formation, an exploration well, and/or equipment in the exploration well, such as production piping. Treatment agents can be in the form of liquids, gases, solids, semi-solids and mixtures thereof. Illustrative treatment agents include, but are not limited to, fracturing fluids, stimulation fluids, acids, steam, water, brine, anti-corrosion agents, cement, permeability modifiers, drilling muds, emulsifiers, demulsifiers, flags, flow, etc. Illustrative well operations include, but are not limited to, hydraulic fracturing, stimulation, flag injection, cleaning, acidification, steam injection, water injection, cementing, etc.

[0086] Although the embodiments described in the present invention have been described with reference to various embodiments, it will be understood that various changes can be made and equivalents can be substituted for elements thereof without departing from the scope of the present disclosure. Additionally, many modifications will be observed to adapt a specific instrument, situation or material to the teachings of the present disclosure without departing from the scope thereof. Therefore, it is intended that the disclosure not be limited to the specific embodiments disclosed as the best contemplated mode of realizing the described features, but that the present disclosure include all embodiments falling within the scope of the appended claims.

[0087] Accordingly, the embodiments of the present disclosure are not to be viewed as limited by the aforementioned description, but are only limited by the scope of the appended claims.

Claims (15)

1. Sensor element (310, 312) for indirectly monitoring cumulative damage to downhole components, the sensor element being characterized by comprising: a sensor body (402, 502) defining an internal cavity (404) , wherein the inner cavity is surrounded by the sensor body (402, 502); at least one electrical wear element (406, 408, 410) located within the sensor body, wherein a portion of the at least one electrical wear element electrically extends from the internal cavity, through the sensor body, and the an exterior of the sensor body, wherein the at least one electrical wear element (406, 408, 410) is configured as a branch of a Wheatstone bridge; and an abrasive substance (414) at least partially filling and containing within the internal cavity, the abrasive substance movable within the internal cavity for contacting and eroding material of the at least one electrical wear element, wherein erosion of the at least an electrical wear element causes a resistance of the at least one electrical wear element to increase, wherein the body of the sensor is configured to prevent the abrasive substance from exiting the internal cavity, wherein the abrasive substance is configured to interact with the at least one electrical wear element within the enclosed internal cavity such that the material of the at least one electrical wear element is removed or worn by the interaction, wherein said interaction reduces a diameter or size of the at least one electrical wear element and increases an electrical resistance of the at least one electrical wear element. Sensor element according to claim 1, characterized in that the at least one electrical wear element is a wire passing through the internal cavity. 3. Sensor element according to claim 1 or 2, characterized in that the at least one electrical wear element comprises three wires, each wire passing through the internal cavity, one of the three wires extending along an X axis, one of the three wires extends along a Y axis, and one of the three wires extends along a Z axis, preferably, the three wires being arranged so that none electrical contact occurs between the three wires. 4. Sensor element according to any one of claims 1 to 3, characterized in that the sensor body has a spherical or cubic format. Sensor element according to any one of claims 1 to 4, characterized in that the sensor body comprises a plurality of plates arranged to form a cube-shaped sensor, with at least a first portion (510) of the at least one electrical wear element is formed along an inner surface of at least one of the plurality of plates facing the inner cavity, preferably the sensor body further comprising a base (506) and each of the plurality of plates are mounted on the base to define the cubic-shaped sensor body, and a second portion (512) of the at least one electrical wear element is disposed on the base. 6. Sensor element according to any one of claims 1 to 5, characterized in that the abrasive substance comprises at least one of particulate matter and gravel or the abrasive substance, at room temperature, comprises a liquid portion and a low-pressure vapor portion viscosity with particles suspended in it. 7. Sensor element according to any one of claims 1 to 6, characterized in that the abrasive substance comprises a fluid and a particulate material, the particulate material being suspended in the fluid, preferably the fluid comprising a supercritical fluid , preferably, the fluid being selected to change phase at a predetermined temperature. 8. Sensor element according to claim 7, characterized in that the sensor body is formed from a material that is electrically insulating and thermally conductive. 9. Sensor element according to any one of claims 1 to 8, characterized in that the sensor body is electrically insulating. 10. Sensor element according to any one of claims 1 to 9, characterized in that the sensor body comprises an insulated portion, where at least one electrical wear element passes through the sensor body in the insulated portion. 11. Monitoring system (300) characterized by comprising: a downhole component (302) comprising at least one electrical element, the downhole component being arranged as part of a downhole tool (302 ) for positioning in an unfinished pit (26, 106); and a sensor assembly (306) mounted to the downhole component, the sensor assembly comprising: at least one sensor element (310, 312) having a sensor body (402, 502) defining an internal cavity (404), wherein the inner cavity is enclosed by the sensor body; at least one electrical wear element (406, 408, 410) located within the sensor body, a portion of the at least one electrical wear element extending electrically from the internal cavity, through the sensor body, and the an exterior of the sensor body, wherein the at least one electrical wear element (406, 408, 410) is configured as a branch of a Wheatstone bridge; and an abrasive substance (414) at least partially filling and containing within the inner cavity, the abrasive substance movable within the inner cavity to contact and erode material of the at least one electrical wear element, wherein erosion of the at least an electrical wear element causes a resistance of the at least one electrical wear element to increase, wherein the body of the sensor is configured to prevent the abrasive substance from exiting the internal cavity, wherein the abrasive substance is configured to interact with the at least one electrical wear element within the enclosed internal cavity such that the material of the at least one electrical wear element is removed or worn by the interaction, wherein said interaction reduces a diameter or size of the at least one electrical wear element and increases an electrical resistance of the at least one electrical wear element. 12. Monitoring system according to claim 11, characterized in that the at least one sensor element comprises a first sensor element (310) and a second sensor element (312), the first sensor element including the abrasive substance in it and the second sensing element is a reference sensing element (312) which does not contain the abrasive substance therein. 13. Monitoring system, according to claim 12, characterized in that it comprises a protective housing (308), with the at least one sensor element being housed within the protective housing. 14. Monitoring system according to any one of claims 11 to 13, characterized in that the downhole component is a printed circuit board. 15. Monitoring system according to claim 14, characterized in that the abrasive substance comprises a fluid and a particulate material, the particulate material being suspended within the fluid.