Method and system for determining depth of a deployed object

Abstract

Method and system (100) for determining depth of an object (320) deployed into a hole or hollow member or structure (330) by a deployment means (340) based on the use of at least one rotating distance measurement assembly (110) arranged in engagement with a deployment means (340), enabling calculation of the depth of the deployed object (320).

Description

[0001] Method and system for determining depth of a deployed object

[0002] The disclosed embodiments relate to a method for determining depth of an object deployed into a hole or hollow member or structure.

[0003] The disclosed embodiments also relate to a system for determining depth of an object deployed into a hole or hollow member or structure.

[0004] The disclosed embodiments especially relate to the use of at least one rotating distance measurement assembly in engagement with a deployment means for deploying the object into the hole or hollow member or structure, wherein at least one sensor or sensor assembly is arranged to or within a rotation member and rotates with the rotation member.

[0005] Background

[0006] Distance measurements can be performed by a variety of methods, whereas the use of wheels is common. The wheel is either rolled along the surface where the distance is to be measured, or the item to be measured is pulled along the outer surface of the wheel. Examples of the latter may include measuring the distance of a section of cable, rope, wire, and so forth. In, e.g., the drilling and borehole surveying industry wheel systems are utilized to measure the length of wireline lowered or pulled out of a drill string or borehole. Similar applications are known from (drill) holes, tubes, pipes or pipelines and other hollow structures in relation to sewer, drainage, water, oil and gas, as well as in the process industry. Other examples are pipes or pipelines for guiding power or communication cable onshore or offshore. Further, it is often desired to know depth of nature- or human-made holes.

[0007] When a wheel is used to measure distance, it typically interfaces with an encoder that counts the number of rotations the wheel is subjected to. Combining this with the known circumference of the wheel itself, allows for measuring the distance. An encoder is a position sensor that determines angular position, or change in angular position, of a rotating shaft. Multiple types exist and may use mechanical, optical and magnetic solutions to detect the rotation of the shaft. In high speed and high accuracy application the optical encoders are most common. These will typically rely on a coded disc that rotates with the shaft and a stationary light source and light sensor that counts or detects the codes on the disc. An example of such a solution is US H1289 H.

[0008] There are multiple practical drawbacks with encoders, particularly in rough applications like wire counters as found in the drilling industry. The encoders typically have the shaft integrated, meaning the wheel axle must interface with the shaft. Vibrations, shocks, radial forces, temperature changes and general degradation may over time weaken the mounting and cause the wheel to spin more or less than the shaft thereby rendering the distance measurements inaccurate. This further makes the encoder and measuring system more difficult to repair and replace.

[0009] Encoders further incorporates fine mechanics with rotating and non-rotating components, making them sensitive to dust, debris, and water. Due to the moving parts, it can be difficult to properly protect an encoder and it may significantly increase the price of the system.

[0010] Encoders are often relatively power-hungry devices. Hence, a spacious battery solution, or external power supply must also be a part of the measurement system.

[0011] Encoders may also be bulky by themselves, and with the axle mount, the system will often need to be designed around the encoder and thereby prevent achieving a design that is optimized for the actual use of the system.

[0012] There is accordingly a need for a method and system for determining depth of an object deployed into a hole or hollow member or structure removing the requirement of the use of an encoder.

[0013] Summary

[0014] The disclosed embodiments provide a method and system for determining depth of an object deployed into a hole or hollow member or structure, partly or entirely solving the problems and deficiencies of the prior art discussed above. Provided herein is a method and system for determining depth of an object deployed into a hole or hollow member or structure removing the requirement of an encoder.

[0015] Also provided herein is a method and system for determining depth of an object deployed into a hole or hollow member or structure avoiding the need for arrangement of distance measurement sensor(s) in connection with or to an axle of the rotation member.

[0016] Provided herein is a method and system for determining depth of an object deployed into a hole or hollow member or structure using at least one rotating distance measurement assembly formed by a rotation member and at least one inertial sensor or sensor assembly arranged thereto or embedded therein.

[0017] Also provided herein is a system for determining depth of an object deployed into a hole or hollow member or structure providing detachable arrangement of the at least one sensor or sensor assembly to the rotating member enabling service or replacement at any time, without the need for replacing other parts.

[0018] Provided herein is a system for determining depth of an object deployed into a hole or hollow member or structure that is easy to protect from dirt and water.

[0019] Also provided herein is a method and system for determining depth of an object deployed into a hole or hollow member or structure that does not rely on additional rotating or non-rotating components.

[0020] Provided herein is a method and system for determining depth of an object deployed into a hole or hollow member or structure capable of handling challenging conditions with vibrations, shocks and high radial forces present in many application areas.

[0021] Also provided herein is a method and system for determining depth of an object deployed into a hole or hollow member or structure involving lower costs both for production, installation and maintenance, compared to prior art solutions.

[0022] Provided herein is a method and system for determining depth of an object deployed into a hole or hollow member or structure having lower power consumption / requirements than prior art solutions.

[0023] Also provided herein is a method and system for determining depth of an object deployed into a hole or hollow member or structure not requiring redesign or modifications of the object or associated deployment means that are to be distance / depth measured.

[0024] Provided herein is a method and system for determining depth of an object deployed into a hole or hollow member or structure able to accurately measure the depth / distance over a longer operational life compared to prior art solutions.

[0025] Also provided herein is a method and system for determining depth of an object deployed into a hole or hollow member or structure having a wide area of applications.

[0026] Also provided herein is a method and system for determining depth of an instrument deployed into a drill hole, drill string or casing.

[0027] Further objects will appear from the following description, claims and attached drawings. The invention

[0028] A method for determining depth of an object deployed into a hole or hollow member or structure according to the present invention is defined by the technical features of claim 1. Preferable features of the method are described in the dependent method claims.

[0029] A system for determining depth of an object deployed into a hole or hollow member or structure according to the present invention is defined by the technical features of claim 11. Preferable features of the system are described in the dependent system claims.

[0030] The measurement principle of the method and system according to the present invention is based on the use of at least one rotating distance measurement assembly arranged in engagement with a deployment means associated with an object for deployment into a hole or hollow member or structure wherein the at least one rotating distance measurement assembly is capable of determining distance / depth measurement of the deployed object. In accordance with the present invention, the at least one rotating distance measurement assembly is formed by a rotation member and at least one inertial sensor or sensor assembly arranged thereto or embedded therein. In accordance with the present invention, the deployment means may be, but is not limited to, a cable, wire, rope, coiled tubing or similar item for lowering, pushing or pulling the object into or out of the hole or hollow member or structure. According to the present invention, the hole or hollow member or structure may be, but not limited to, a drill hole, drill string, casing, tube, pipe, pipeline or combination thereof. Other examples of members or structures will be within the knowledge of a skilled person within the art.

[0031] The measurement principle of the method and system according to the present invention is based on measuring accelerations as the rotating distance measurement assembly (rotation member) is rotated and the calculation of distance / depth based on the measured accelerations and outer circumference of the rotation member. The measurement of accelerations also enables derivation of angular rate or change.

[0032] The method for determining depth of an object according to the present invention comprises arranging the at least one rotating distance measurement assembly in engagement with a deployment means associated with the object for deployment into a hole or hollow member or structure, deploying the object into the hole or hollow member or structure, and determining the depth thereof. The method according to the present invention comprises applying rotation to the rotation member by movement of the deployment means.

[0033] According to the present invention, the method comprises, during the rotation of the rotation member, determining the angular change of the rotation member by using sensor data from the at least one inertial sensor or sensor assembly.

[0034] The method according to the present invention further comprises calculating the distance the deployment means has moved the rotation member and thus the depth of the deployed object based on determined angular change and outer circumference of the rotation member. In the terms of the present invention, the calculated distance can also be considered as the deployed length of the deployment means.

[0035] In accordance with one embodiment of the method according to the present invention, the method comprises determining angular change by using at least one accelerometer, at least one gyroscope, or a combination thereof, or an inertial measurement unit.

[0036] According to a further embodiment of the method according to the present invention, the method comprises determining angular change by measuring angular rate and / or change in acceleration.

[0037] According to a further embodiment of the method according to the present invention, the method comprises using at least one gyroscope to detect angular rate and quantify change in speed and centripetal acceleration of the rotation member.

[0038] In accordance with one embodiment of the method according to the present invention, the method comprises using sensor data from at least one gyroscope as direct input in the distance / depth measurement calculation or to compensate sensor data from the at least one accelerometer.

[0039] According to one embodiment of the present invention, the method comprises analysing the sine wave cycles of the acceleration measurements from the at least one sensor or sensor assembly to provide a measure of angular change of the rotation member.

[0040] According to another embodiment of the present invention, the method comprises calculating angular change directly from the accelerometer output, or from a filtered or adjusted accelerometer output. In accordance with one embodiment of the present invention, the method comprises calculating deployed distance of the deployment means and thus depth of the deployed object by number of rotations of the rotation member x outer circumference of the rotation member.

[0041] According to one embodiment of the present invention, the method comprises using the following formula for calculating the deployed distance of the deployment means and thus depth of the deployed object: n x radius of rotation member x angular change, where angular change is expressed in radians and include the number of revolutions.

[0042] The system according to the present invention comprises at least one rotating distance measurement assembly arranged in engagement (contact) with a deployment means associated with an object for deployment into a hole or hollow member or structure and depth measurement. The at least one rotating measurement assembly is formed by a rotation member and at least one inertial sensor or sensor assembly arranged into or onto the rotation member.

[0043] In accordance with one embodiment of the present invention, the at least one inertial sensor or sensor assembly is detachably arranged into or onto the rotation member.

[0044] According to one embodiment of the present invention, the at least one rotating distance measurement assembly will be in direct engagement / contact with the deployment means associated with the deployed object to be depth measured by the rotation member. In alternative embodiments, the measurement principle may also be utilized for applications where the rotation member is in indirect engagement / contact with the deployment means associated with the deployed object to be depth measured.

[0045] According to the present invention the at least one inertial sensor or sensor assembly comprises at least one accelerometer, or at least one gyroscope, or a combination, or an inertial measurement unit (IMU) containing both accelerometers and gyroscopes. The mentioned at least one inertial sensor or sensor assembly may further be configured for measuring angular rate or change in acceleration.

[0046] The system according to the present invention further comprises a control unit configured, by comprising means and / or software, to retrieve sensor data from the at least one inertial sensor or sensor assembly and storage of data in an internal and / or external memory for internal or external processing of retrieved sensor data in real-time or for post processing (offline) of the stored / logged data. In accordance with a further embodiment of the control unit, the control unit is configured, by comprising means and / or software, to determine angular change from the measured angular rate and / or change in acceleration.

[0047] The control unit is according to a further embodiment of the present invention provided with wired or wireless communication means or arranged to a communication module with wired or wireless communication means for communication with embedded or external units, such a user terminal.

[0048] In accordance with the present invention, the system further comprises a user terminal enabling presentation of measurement information for a user. Examples of user terminals may include an embedded display or an external display, a computer or a handheld unit such as a smart phone, tablet or similar. The communication with user terminals in the form of external devices is preferably wireless.

[0049] In accordance with the present invention, the components of the system may be mounted together into one unit or be separated into multiple units. The former is preferable to secure ease of overall use and assembly. The latter may in some cases be preferable in order to distribute weight and maintain rotation member balance during rotation. Communication between each component / unit may in such case be achieved via conducting cable or wirelessly.

[0050] The rotation member according to the present invention is circular and is arranged to a support structure, stationary or movable, via a center axle. The rotation member is accordingly arranged freely rotating to the support structure by means of the center axle.

[0051] According to the present invention, the at least one inertial sensor or sensor assembly is arranged to or embedded in the rotation member at any location at or between the rotation member center axle and outer circumference or surface thereof, for instance on a spoke.

[0052] Arrangement of the at least one inertial sensor or sensor assembly closer to the center axle is preferable to reduce the centripetal acceleration and its effect on the at least one inertial sensor or sensor assembly.

[0053] Besides from the arrangement of the at least one inertial sensor or sensor assembly to the rotation member, the at least one inertial sensor or sensor assembly is otherwise fully independent of the rotation member, such that the system is straightforward to detach for replacement or repackaging. According to one embodiment of the present invention, the at least one inertial sensor or sensor assembly and other electronics are mounted in a dust and water / pressure proof housing, which may vary according to the requirements of the application in question.

[0054] The independent nature of the system, where one simply arranges (attaches) at least one inertial sensor or sensor assembly to a rotation member, makes it independent from the application, and the same inertial sensor or sensor assembly and electronics may be utilized equally well in high temperature conditions or under water, as in any other application.

[0055] Accordingly, the distance measurement and thus depth measurement is performed by the at least one rotating distance measurement assembly arranged in engagement with a deployment means associated with an object deployed into a hole or hollow member or structure to be depth measured. In accordance with the present invention, rotation of the rotation member is affected by movement of the deployment means associated with the deployed object.

[0056] In this manner, when the object is deployed or retrieved, this results in rotation of the rotation member

[0057] Accordingly, regardless of the application, the measuring principle is based on rotation of a rotation member and determining angular change based on measurements from at least one inertial sensor or sensor assembly arranged in a fixed position on the rotation member and as the rotation member rotates, the at least one inertial sensor or sensor assembly rotates correspondingly.

[0058] As the rotation member is rotated, the at least one inertial sensor or sensor assembly will rotate at the same angular rate as the rotation member.

[0059] During the measurement process, the at least one inertial sensor or sensor assembly continuously registers acceleration and / or angular rate data, that will be used to calculate the distance of the deployment means and thus depth of the deployed object.

[0060] In accordance with one embodiment of the present invention, the at least one inertial sensor or sensor assembly is at least one accelerometer. Rotating accelerometer(s) produce sensor data signals that resemble a sine wave around each axis. The number of cycles thus corresponds to the number of rotations of the rotation member.

[0061] According to one embodiment of the present invention, the at least one inertial sensor or sensor assembly is at least one gyroscope. Rotating gyroscope(s) produce sensor data signals that are directly proportional to the rotation rate. In accordance with one embodiment of the present invention, the at least one inertial sensor assembly comprises at least one accelerometer and at least one gyroscope, or an IMU.

[0062] The mentioned characteristics from the at least one inertial sensor or sensor assembly, digital signal processing and the known circumference of the rotation member form the basis for deriving the distance / depth measurement according to the present invention.

[0063] The sine wave characteristics from the at least one accelerometer will be affected by changes in rotation member / rotational speed. In a system where the rotation member is moving with a constant rotational velocity, the centripetal acceleration remains constant and the at least one accelerometer will output a repeating wave form. However, during the start, stop, while vibrating or at any other point where the rotation member speed changes, the centripetal acceleration also changes and affects the wave form output from the at least one accelerometer. A constant and very high speed may also cause similar effects if the centripetal acceleration nears the limits of the accelerometer. Similar issues occur if the centripetal acceleration becomes high for other reasons.

[0064] In accordance with the present invention, by providing the at least one inertial sensor assembly with at least one gyroscope in addition to at least one accelerometer, the at least one gyroscope, during such periods, is utilized to detect and quantify the change in speed and centripetal acceleration.

[0065] In accordance with one embodiment of the present invention, the control unit is configured, by comprising means and / or software, to use gyroscope sensor data either as direct input in the distance / depth measurement calculation, or to compensate the accelerometer data. By correlating the angular rate measured by the gyroscope sensor with the time or duration of the measurement process a direct measure of the angular change is found. However, since gyroscope sensors typically are subject to drift the accuracy of the angular change may be affected when measuring over longer periods. For this reason, it is preferable to use gyroscopes in combination with accelerometers and use data from one to compensate the other. In its simplest form this may be done by replacing the angular change determined by the accelerometer with the angular change determined by the gyroscope, for instance to correct for short term rapid accelerations of the rotation member. Alternatively, or additionally, compensation may be performed by calculating centripetal acceleration from the gyroscope data (angular rate) and use this to adjust the accelerometer data accordingly. Such compensation requires the knowledge of the radial position of the accelerometer sensor(s) and is calculated from standard formulas for circular motion. Centripetal acceleration is proportional to radius (distance to inertial sensor) times angular rate squared. This latter form of compensation may be performed equally well in the opposite direction, or both directions, enabling usage of accelerometer data for compensation of gyroscope sensor drift.

[0066] The method and system for distance measurement according to the present invention is applicable for a wide range of user applications, such as, but not limited to: clamping to pulleys or wheels for measuring distance of cable, wire, rope, chain, hoses, pipe, snake / tape, etc.

[0067] The principles of the present invention are also applicable for distance measuring roller wheels for construction (not a part of the present invention), and arrangement (clamping or embedded) to a wheel travelling over a surface, such as a wheel on a traveling manual or automated vehicle or craft, such as bicycles, cars, remotely operated vehicle, etc. (not a part of the present invention).

[0068] The method and system for distance measurement is applicable for different applications. One such application is within the drilling industry, wherein the method and system for distance measurement according to the present invention can be used for determining depth of an object deployed in a drill hole. In one embodiment the object is an instrument selected from the group comprising deviation survey instruments, geophysical instruments, sensor packages, imaging instruments, cameras, weights or other instruments or equipment deployed in a drill hole with a wireline or similar means. It would be understood that the object to be deployed may comprise a single instrument or a cluster or row of two or more instruments or sensors.

[0069] Instruments are typically deployed and retrieved from a drill hole, drill string or casing by suitable deployment means, including, but not limited to, a cable, wire, rope, coiled tubing and similar. By arranging the rotation member of the present invention in engagement with this deployment means, the current distance of the deployment means can be measured as the instrument is deployed into the drill hole, drill string or casing. The instrument can be deployed into drill holes at any angle, including vertical and horizontal drill holes. In certain applications depth measurement may commence at the top of a drill hole and continue all the way to the bottom of the drill hole and be repeated as the (downhole) instrument is retrieved. Lowering and retrieving the deployment means is typically done with a winch, however push / pull rodder systems, pulley systems or hand force may in some cases be used. The system and method can also be used to measure depth of holes at any angle, including upward holes or horizontal holes, in underground mining or civil applications.

[0070] In one embodiment of the present invention, the system is integrated as a part of a counter assembly that contains a measuring wheel in engagement with the deployment means. Accordingly, the rotation member in the present invention is thus the measuring wheel of the counter assembly. In accordance with a further embodiment of the present invention, the rotation member is a pulley wheel guiding the deployment means into the drill hole, drill string or casing.

[0071] In one embodiment of the present invention, the rotation member is caused to rotate by the movement of the deployment means. In alternative embodiments the rotation member is caused to rotate by manual rotation of a handle or other such device, or by a motorised system, thereby deploying the deployment means and thus the object.

[0072] The measurement principle according to the present invention may also be utilized via indirect engagement / contact with the deployment means associated with the deployed object (instrument) to be depth measured. An example of such an embodiment is wherein the rotation member is a winch drum, where the outer diameter of the drum would be related to the amount of wire left on it, making it more complex to determine accurate depth data.

[0073] When deploying an object (instrument) into a drill hole, the object (instrument) is first placed in the start section of the drill hole, drill string or casing, and the depth data adjusted to zero. As the object (instrument) is deployed into the drill hole, drill string or casing, depth data is continuously transmitted and displayed at the user terminal. The direct knowledge of the current depth allows the operator to slow down the speed of the deployment means as the deployed object (instrument) nears the end of the drill hole, drill string or casing, or at any other depths a lower, or higher, speed is desired. Likewise, when the deployed object (instrument) is retrieved, the speed of the deployment means may be reduced as the deployed object (instrument) nears the start of the drill hole, drill string or casing.

[0074] Once the object (instrument) is back on surface, the depth data may be used to relate the object (instrument) sensor data to the correct position in the drill hole, drill string or casing. The depth data may either be stored in the user terminal continuously during the deployment and / or retrieval process, or stored internally in the memory of the system for distance measurement and transferred to the user terminal after the end of the deployment and retrieval process. The latter gives extra security in case the wireless communication is temporarily lost at any point during the deployment and retrieval process.

[0075] The present invention further provides a method and system that requires few components and which is simple to assemble and dismantle, as well as enable easy maintenance and replacement.

[0076] By the present invention is provided a solution that is easy to protect for harsh environments, such as dirt and water. The present invention further provides a solution that is capable of handling challenging conditions with vibrations, shocks and high radial forces present in many application areas. Accordingly, the present invention will be able to accurately measure the distance / depth over a longer operational life compared to prior art solutions.

[0077] The present invention provides a solution involving lower costs both for production, installation and maintenance, compared to prior art solutions.

[0078] By the present invention is provided a solution that can be retrofitted to existing applications as well as be integrated in new applications.

[0079] Further preferable features and advantageous details of the present invention will appear from the following example description, claims and attached drawings.

[0080] Example

[0081] The present invention will now be described in further detail with reference to the attached drawings, where:

[0082] Fig. la-b are principle drawings of a system according to the present invention,

[0083] Fig. 2 is a non-limiting example of the measuring principle according to the present invention, and

[0084] Fig. 3 is a non-limiting usage example of the present invention.

[0085] Reference is now made to Fig. la-b showing a principle drawing of system 100 for distance / depth measurement according to one embodiment of the present invention. The system 100 according to the present invention comprises at least one rotating distance measurement assembly 110 formed by a rotation member 120 and at least one inertial sensor 210, 220, 230 or sensor assembly 200 arranged to or into the rotation member 120.

[0086] The rotation member 120 according to the present invention has a circular known outer circumference 121. In accordance with the present invention, the rotation member 120 is a dedicated rotation member 120 of the system according to the present invention or a rotation member 120 already present in a system for an object 320 to be deployed into a hole or hollow member or structure 330 and depth measured. In the shown embodiment, the rotation member 120 is provided with a centre axle 130 enabling rotation of the rotation member 120 in relation to a support structure 400 (see Fig. 3).

[0087] In the shown embodiment of the rotation member 120, shown as a wheel, has spokes 122 extending from the centre axle 130 and towards the outer circumference 121 (wheel rim). The rotation member 120 may further be any suitable object with a circular outer circumference 121 and wherein a centre axle 130 may be arranged, such as, but not limited to, pulleys, tubular members, discshaped members, spools, etc.

[0088] According to a further embodiment of the rotation member 120 according to the present invention, the outer circumference 121 is provided with a circumferentially extending recess or other engagement means (not shown) adapted for receiving and accommodating a deployment means 340 (see Fig. 3) associated with an object 320 to be deployed into a hole or hollow member or structure 330 and depth measured. The object 320 to be deployed and depth measured may be any object or instrument that is deployed in a drill hole with a wireline or similar means, such as, but not limited to, survey instruments, deviation survey instruments, geophysical instruments, sensor packages, cameras, weights or other instruments or equipment. The object 320 to be deployed may comprise a single instrument or a cluster or row of two or more instruments or sensors.

[0089] The mentioned at least one inertial sensor 210, 220, 230 or sensor assembly 200 according to the present invention is arranged to or into the rotation member 120. In the shown example, the at least one inertial sensor 210, 220, 230 or sensor assembly 200 is arranged to a spoke 122 of the rotation member 120. If the rotation member 120 is solid, the rotation member 120 typically is provided with one or more recesses for receiving and accommodating the at least one inertial sensor 210, 220, 230 or sensor assembly 200 and detachably attaching it into the rotation member 120 by at least one fastening device 140, such as a clip-on / snap-on system or similar, or by nuts and bolts, screws or similar, enabling easy detachment of the at least one inertial sensor 210, 220, 230 or sensor assembly 200 from the rotation member 120. In the embodiment with the recess for receiving and accommodating the at least one inertial sensor 210, 220, 230 or sensor assembly 200, the recess will be designed for or comprises at least one fastening device 140 for fixation of the at least one inertial sensor 210, 220, 230 or sensor assembly 200. Other fastening devices 140 will be within the knowledge of a skilled person, to ensure that the at least one inertial sensor 210, 220, 230 or sensor assembly 200 is fixed to or into the rotation member 120.

[0090] Reference is now made to Fig. lb which is a block diagram of a system according to the present invention. The at least one inertial sensor 210, 220, 230 or sensor assembly 200 according to the present invention comprises at least one inertial sensor 210, 220, 230 configured to measure accelerations. According to the present invention, the at least one inertial sensor 210, 220, 230 or sensor assembly 200 comprises at least one accelerometer 210, or at least one gyroscope 220, or a combination, or an inertial measurement unit (IMU) 230 containing both accelerometer(s) and gyroscope(s).

[0091] In accordance with one embodiment of the present invention, the at least one inertial sensor 210, 220, 230 or sensor assembly 200 comprises one accelerometer 210 configured to measure accelerations in at least two measurement axes. Alternatively, the at least one inertial sensor 210, 220, 230 or sensor assembly 200 comprises at least two single axis accelerometers (not shown) configured to measure accelerations in different measurement axes. The mentioned two measurement axes are preferably arranged perpendicular to each other and directed in the radial plane of the rotation member 120, such as the wheel.

[0092] Reference is now also made to Fig. 2 showing output from a two-axis accelerometer 210. As the rotation member 120 is rotated in one direction, the accelerometer 210 data values present as a sine wave, where a full rotation of the rotation member 210 corresponds with a full cycle.

[0093] If the rotational direction of the rotation member 120 changes, the accelerometer 210 output also changes direction. The sine waves in Fig. 2 illustrates two cycles in one direction followed by two cycles in the opposite direction, indicating that the rotation member 120 has first been rotated two rotations in one direction followed by two rotations in the opposite direction. The travelled distance is thus given as the 2 x the outer circumference of the rotation member 120 in each direction, ending back at the starting point.

[0094] While any distance and thus depth may be calculated this way by carefully analyzing the sine wave, it is in a digital sense easier to utilize the inertial sensor data output directly. When the maximum and minimum inertial sensor output is known, the angular position of any data output may be calculated using basic trigonometry. This way the angular starting position is known and can be recalculated any time the data output changes. By adding all changes in angular position occurring over the measurement period and subtracting the angular starting position the total angular change is found. The distance (and depth) may now be calculated as Distance = n x radius of rotation member x angular change, where angular change is expressed in radians and include the number of revolutions.

[0095] The use of two perpendicular accelerometer 210 axes ensures that changes in rotational direction of the rotation member 120 can always be detected. If only measuring along one axis it will not be possible to detect a change in rotational direction that occurs at the top or bottom of the sine wave (max / min amplitude). From the maximum value, the accelerometer 210 output will reduce independent of the direction the rotation member 120 is rotating, and opposite from the minimum value. Adding a second accelerometer 210 axis secures that usable data is available when one axis is at maximum or minimum, ensuring that changes in direction can be detected at all times.

[0096] In accordance with a further embodiment of the present invention, the at least one accelerometer 210 is configured to measure in a third accelerometer axis being perpendicular to the rotation member 120, parallel with the rotation member 120 axle axis. This will provide information about possible rotation member 120 tilt angle and total acceleration. In an alternative embodiment, the sensor assembly 200 comprises a third single axis accelerometer 210 for this.

[0097] It should be mentioned that the at least one sensor assembly 200 may comprise a combination of single axis, two-axis and three-axis accelerometers 210 to achieve the above mentioned three measurement axes.

[0098] A rotating gyroscope 220 produce data signals that are directly proportional to the rotation speed. With knowledge of time, this may be utilized to calculate angular change directly. However, as gyroscope sensors are commonly prone to drift the sensor data may over time become unreliable. The drift causes the gyroscope sensor to register a higher or lower angular rate than the actual. While some drift may be compensated for, for instance by stopping the rotation for a certain period and detecting changes that occur, the procedures affect operation and may not achieve full compensation of the drift. Instead of relying solely on a gyroscope sensor for angular change determination, the gyroscope sensor may be combined with accelerometer sensor(s). As described earlier, each sensor type may be used to compensate and correct for the other and significantly improve the distance measurement accuracy of the system.

[0099] The system according to the present invention further comprises an embedded or external control unit 240 configured, by comprising means and / or software, to retrieve sensor data from the at least one inertial sensor 210, 220, 230 or sensor assembly 200.

[0100] The control unit 240 is configured, by comprising means and / or software, to store sensor data from the at least one inertial sensor 210, 220, 230 or sensor assembly 200 in an internal memory 241 or an external memory. In accordance with one embodiment of the present invention, the control unit 240 is configured, by comprising means and / or software, for internal processing of the retrieved sensor data in real-time, or post-processing (offline).

[0101] The control unit 240 is according to a further embodiment provided with wired or wireless communication means 242 or arranged to a communication module with wired or wireless communication means (not shown).

[0102] In accordance with the present invention, the system further comprises a power system / unit 250 for powering the components of the system, mentioned above. Power to the system components is preferably provided by an energy storage (battery or battery pack), which may be either replaceable or rechargeable, and / or comprising energy harvesting means. A skilled person will be familiar with these alternatives and no further description is required herein.

[0103] In accordance with the present invention, the measurement information is presented to a user on at least one embedded or external user terminal 260. The at least one user terminal 260 is, e.g., an embedded display or an external display, a computer or a handheld unit, such as a smart phone, tablet or similar, or a combination thereof. For communication with at least one external user terminal 260, the communication means 242 are preferably wireless, but may also be wired, especially for post-processing applications.

[0104] According to one embodiment of the present invention the mentioned wireless communication means 242 for communication with the at least one external user terminal 260 comprises an antenna system as described in NO344403 (in the name of the applicant) is utilized. Other antenna systems, and wired solutions, are also possible, which solutions will be within the knowledge of a skilled person.

[0105] In a further embodiment of the present invention, the at least one external user terminal 260 is configured, by comprising means and / or software, to process the stored / logged sensor data in realtime or post-processed (offline).

[0106] The user terminal 260 is in addition to displaying information preferably also configured, by comprising means and / or software, to control the settings of the at least one inertial sensor 210, 220, 230 or sensor assembly 200, such as sampling rate, start or stop of the logging process, power saving, calibration, etc. If the system is used to another application one will have to update the system with the circumference, radius, etc. used in the mentioned calculations. In accordance with one embodiment of the present invention the at least one inertial sensor 210, 220, 230 or sensor assembly 200 is arranged in a protective housing 201 adapted to the required conditions to protect the components from dirt and water. The control unit 240 and / or user terminal 260 may also be arranged in separate housings for the same reason or embedded in the same housing 201 as the at least one inertial sensor 210, 220, 230 or sensor assembly 200.

[0107] Reference is now made to Fig. 3 showing an application using the distance measuring principle according to the present invention.

[0108] Fig. 3 shows a borehole / drill hole survey system 300 wherein the object 320 to be deployed and depth measured is a downhole instrument. A winch 310 controls deployment and retrieval of the downhole instrument 320 to and from a hole or hollow member or structure 330 in the form of a drill hole, drill string or casing by means of a deployment means 340, typically but not limited to a wireline / slickline or conducting cable.

[0109] The winch 310 comprises a drum 311 on which the deployment means 340 is reeled. The winch 310 further comprises at least one controllable motor 312 controlling the deployment and retrieval of the deployment means 340, as well as the deployment speed, and thus also the deployment and retrieval of the downhole instrument 320. It would be understood that the at least one controllable motor 312 could be replaced with a manual means for controlling the deployment and retrieval of the deployment means 340, such as a handle.

[0110] The rotation member 120, in the form of a pulley system, is configured to guide the deployment means 340 into the drill hole, drill string or casing 330. The deployment means 340 is releasably engaged with the downhole instrument 32O.The deployment means 340 can be attached to the object 320 (instrument) by a suitable means, which includes but is not limited to: shackles, wire clamps, quick couplings, threaded couplings or typical couplings found in the drilling industry such as spearhead couplings, socket adaptors and similar.

[0111] In the shown embodiment, the pulley system is formed by the mentioned rotation member 120 in the form of a guide wheel, and a support structure 400, such as a stand or attachment system, wherein the rotation member 120 is arranged rotatably to the support structure 400 via the centre axel 130, and wherein the at least one inertial sensor 210, 220, 230 or sensor assembly 200 is arranged to and fixed to a spoke 121 of the rotation member 120. The support structure 400 is positioning and securing the rotation member 120 in a suitable position near an upper end of the drill hole, drill string or casing 320. The rotation member 120 comprises a circumferential engagement means for engaging with the deployment means 340, whereby movement of the deployment means 340 causes rotation of the rotation member 120. The engagement between the rotation member 120 and the deployment means 340 may be permanent or temporary. In one embodiment the rotation member 120 comprises an engagement for detachable engagement with the deployment means 340. Accordingly, the deployment means 340 may be attached to and detached from the rotation member 120 as needed. Suitable means can be used for attachment, including but not limited to gravity, clamps, springs, latches and support wheels. Accordingly, the at least one inertial sensor 210, 220, 230 or sensor assembly 200 will rotate with the guide wheel / rotation member 120 as the deployment means 340 is discharged from or reeled onto the winch 310 as the downhole instrument 320 is deployed in the drill hole, drill string or casing 330. In particular embodiments the object 320 (instrument) is deployed in a downward vertical direction. In alternative embodiments the object 320 (instrument) is deployed at any required angle, including horizontal, vertical or any angle therebetween.

[0112] The at least one inertial sensor 210, 220, 230 or sensor assembly 200 transfers the sensor (measurement) data wirelessly to the user terminal 260 for displaying. The sensor data is sent continuously or at high frequency giving the user direct feedback on the current depth as the downhole instrument 320 is deployed into or retrieved from the drill hole, drill string or casing 330.

[0113] With this information the user can monitor the speed during the survey, and reduce the speed as the downhole instrument 320 is nearing the drill hole, drill string or casing 330 opening or end to avoid damages to the downhole instrument 320 and unsafe situations.

[0114] The system according to the present invention enables the calculation of velocity of a deployment means 340 in all applications. In many applications it will be preferable to log velocity of the or object during the distance measurement, such as e.g. velocity of the cable, wire or rope 340 during a drill hole survey. In accordance with one embodiment of the present invention, the internal or external control unit 240, 260 is configured, by comprising means and / or software, to log time together with sensor data. One can then use the time between measure points and calculate the velocity based on this as. Accordingly, in accordance with one embodiment of the present invention, the internal or external control unit 240, 260 is configured, by comprising means and / or software, to calculate velocity of the item based on: Adistance / Atime. This also enables the calculation of velocity of the vehicles or crafts, which is not a part of the present invention. In accordance with one embodiment of the present invention, the at least one rotation member 120 is provided with two or more inertial sensors 210, 220, 230 or sensor assemblies 200 with the same or different specifications at different locations. In this manner one may achieve redundancy or improved measurement results. In a further embodiment of the present invention, two or more rotating distance measurement assemblies 110 are used, with the same or different specifications, for measuring distance of the cable, wire or rope 340 and thus depth of the downhole survey instrument / instrument 320 (instrument), e.g., by integration in two different pulleys of a pulley system.

[0115] According to a further embodiment of the present invention, the at least one rotating distance measurement assembly 110 comprises two or more rotation members 120 provided with at least one inertial sensor 210, 220, 230 or sensor assembly 200, with the same or different specifications, for measuring distance of a deployment means 340 and thus depth of the deployed object 320 (instrument). E.g. by integration of two independent parallel rotation members 120 in a support structure 400, either arranged in longitudinal direction or transversal direction, wherein both rotation members 120 are independently in contact with the deployment means 340.

[0116] In these latter embodiments one also achieves redundancy or improved measurement results.

[0117] The above described embodiments may be combined to form modified embodiments within the scope of the attached claims.

Claims

Claims1. Method for determining depth of an object(320) deployed into a hole or hollow member or structure (330) by a deployment means (340), wherein the method comprises arranging at least one rotating distance measurement assembly (110) in engagement with the deployment means (340), the at least one rotating distance measurement assembly (110) being formed by a rotation member (120) and at least one inertial sensor (210, 220, 230) or sensor assembly (200) arranged thereto or embedded therein, wherein the at least one inertial sensor (210, 220, 230) or sensor assembly (200) forms basis for determining angular change, wherein the method comprising: applying rotation to the rotation member (120) by movement of the deployment means (340) during the rotation of the rotation member (120) measuring acceleration and / or angular rate with the at least one inertial sensor (210, 220, 230) or sensor assembly (200), and calculating the distance of the deployment means (340) and thus depth of the deployed object (320) based on determined angular change and outer circumference of the rotation member (120).

2. Method according to claim 1, comprising measuring accelerations and / or angular rate by using at least one accelerometer (210), at least one gyroscope (220), or a combination thereof, or an inertial measurement unit (230).

3. Method according to claim 2, comprising using at least one gyroscope (220) to detect and quantify change in speed and centripetal acceleration of the rotation member (120).

4. Method according to claim 3, comprising measuring or calculating angular rate or change in acceleration.

5. Method according to claim 3, comprising using sensor data from at least one gyroscope (220) as direct input in the distance / depth measurement calculation or to compensate sensor data for the at least one accelerometer (210).

6. Method according to claim 2, comprising analysing the sine wave cycles from measured accelerations from the at least one inertial sensor (210, 220, 230) or sensor assembly (200) to provide a measure of angular change of the rotation member (120).

7. Method according to claim 6, comprising calculating distance of the deployment means (340) and thus depth of the deployed object (320) by number of rotations of the rotation member (120) x outer circumference of the rotation member (120).

8. Method according to claim 7, comprising calculating distance of the deployment means (340) and thus depth of the deployed object (320) from: nx radius of rotation member (120) x angular change.

9. Method according to any preceding claim, wherein the hole or hollow member or structure (330) is a drill hole, drill string, casing, tube, pipe, pipeline or combination thereof.

10. Method according to any preceding claim, wherein the object (320) is selected from the group comprising survey instruments, deviation survey instruments, geophysical instruments, sensor packages, cameras, weights or other instruments or equipment.

11. System (100) for determining depth of an object (320) deployed into a hole or hollow member or structure (330) by a deployment means (340), wherein the system (100) comprises at least one rotating distance measurement assembly (110) in engagement with the deployment means (340), the at least one rotating distance measurement assembly (110) being formed by a rotation member (120) and at least one inertial sensor (210, 220, 230) or sensor assembly (200) arranged thereto or embedded therein, wherein the at least one inertial sensor (210, 220, 230) or sensor assembly (200) is configured to measure accelerations and / or angular rate when the rotation member (120) is rotated by movement of the deployment means (340) applying rotation to the rotation member (120).

12. System according to claim 11, wherein the system (100) comprises an internal or external control unit (240, 260) configured, by comprising means and / or software, to calculate distance of the deployment means (340) and thus depth of the deployed object (320) based on the measured sensor data and outer circumference of the rotation member (120).

13. System (100) according to claim 11, wherein the at least one inertial sensor (210, 220, 230) or sensor assembly (200) is detachably arranged to or embedded into the rotation member (120).

14. System (100) according to claim 11, wherein the at least one inertial sensor (210, 220, 230) or sensor assembly (200) comprises at least one accelerometer (210), at least one gyroscope (220), or a combination thereof, or at least one inertial measurement unit (230).

15. System (100) according to claim 14, wherein the at least inertial one sensor (210, 220, 230) or sensor assembly (200) is configured for measuring angular rate or change in acceleration.

16. System (100) according to claim 14, wherein the at least one inertial sensor (210, 220, 230) or sensor assembly (200) comprises:- at least two single axis accelerometers (210), arranged with perpendicular measurement axes,- at least one two-axis accelerometer (210), configured with two perpendicular measurement axes,- at least one three-axis accelerometer (210), configured with two perpendicular measurement axes and a third measurement axis perpendicular to the rotation member (120), or- a combination of single axis, two-axis and / or three-axis accelerometers (210).

17. System (100) according to claim 14, wherein the internal or external control unit (240, 260) is configured, by comprising means and / or software, to determine angular change from the measured angular rate and / or change in acceleration.

18. System according to claim 14, wherein the at least one gyroscope (220) is configured to detect and quantify change in speed and centripetal acceleration of the at least one rotation member (120).

19. System (100) according to claim 18, wherein the internal or external control unit (240, 260) is configured, by comprising means and / or software, to use sensor data from at least one gyroscope (220) as direct input in the distance measurement calculation or to compensate sensor data for the at least one accelerometer (210).

20. System (100) according to any preceding claim 11-19, wherein the internal or external control unit (240, 260) is configured, by comprising means and / or software, to analyse the sine wave cycles of the acceleration measurements from the at least one inertial sensor (210, 220, 230) or sensor assembly (200) to provide a measure of angular change of the rotation member (120).

21. System (100) according to claim 20, wherein the internal or external control unit (240, 260) is configured, by comprising means and / or software, to calculating distance of the deployment mean (340) and thus depth of the deployed object (320) by number of rotations of the rotation member (120) x outer circumference of the rotation member (120).

22. System (100) according to claim 21, wherein the internal or external control unit (240, 260) is configured, by comprising means and / or software, to calculate distance of the deployment mean (340) and thus depth of the deployed object (320): yr x radius of rotation member (120) x angular change.

23. System (100) according to any preceding claim 11-22, wherein the system (100) comprises a user terminal (260) for displaying distance measurements and / or depth.

24. System (100) according to any preceding claim 11-23, wherein the at least one inertial sensor (210, 220, 230) or sensor assembly (200) is arranged in a protective housing (201).

25. System according to any of claims 11-24, wherein the hole or hollow member or structure (330) is a drill hole, drill string, casing, tube, pipe, pipeline or a combination thereof.

26. System according to any one of claims 11-25, wherein the object (320) is selected from the group comprising survey instruments, deviation survey instruments, geophysical instruments, sensor packages, cameras, weights or other instruments or equipment.

27. System according to any one of claims 11-26, wherein the deployment means (340) is a wire, cable, rope or coiled tubing, or a combination thereof.

28. System according to any one of claims 11-27, wherein the rotation member (120) comprises an engagement means for detachable engagement with the deployment means (340).

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