A downhole tool

Abstract

A downhole tool (1) comprising: a tool housing (5), a first end (9) and a second end (11), and a longitudinal extension having a longitudinal axis (A), a moveable tool part (13), where in a first operational position the moveable tool part is in a first position relative to the tool housing, and in a second operational position the moveable tool part is in a second position relative to the tool housing, an actuator configured to move the moveable tool part, a resistive sensor (35), having a variable resistor (43), whereby the movement of the movable tool part changes the resistance of the variable resistor to register the position of the moveable tool part relative to the tool housing.

Description

Technical Field

[0001] A downhole tool for submerging into a casing, the tool comprising a tool housing having an outer surface, a first end and a second end, the tool housing also having a longitudinal extension having a longitudinal axis.Description

[0002] In wellbore operations, tools can be introduced into the wellbore to perform particular operations inside an already drilled wellbore, or inside a well tubular (casing) that has been introduced into the wellbore. Such operations may be performed to optimise the production in a wellbore to repair parts that have been introduced into the wellbore.

[0003] A number of these operations are done using downhole tools that may be introduced into a wellbore, where the operation needs to be performed at a certain depth, e.g. if a well tubular has to be repaired or replaced, or e.g. when a valve which is stuck has to be milled out for replacement or removal. These operations are often performed by introducing a downhole tool to a certain depth, where the tool may be anchored via an anchoring part and / or using wheels of a downhole tractor to fix the position of the downhole tool to perform the operation.

[0004] When the operation is to be performed, a part of the tool may be extended from the tool body in a known distance in a radial direction of a wellbore or a longitudinal direction of the wellbore to perform the operation. As an example, if a wellbore tubular is to be cut, a cutter arm is extended in a radial direction from the tool body, where the cutter arm is rotated inside the wellbore to provide a radial cut in the well tubular to separate an upper part of the well tubular from a lower part of the well tubular. Similarly, when a valve is to be milled, a milling head may be extended in a longitudinal direction away from one end of the tool body to mill the valve from the inside of the well tubular.

[0005] However, one problem with such operations is to know when the operation is successfully performed, e.g. the tubing cutter or the milling head, has milled or cut through the obstacle by identifying the position of the moveable tool part. One way of obtaining the position of the tool part has been to attempt to identify the position of a linear actuator by using a pressure sensor to measure the pressure of the hydraulic fluid used to drive the linear actuator.

[0006] However, such measurements are flawed, in that the measurements do not indicate the position of the moveable tool but indicate the force utilised to move the linear actuator. Thus, there is a need to improve the positional measurement of the moveable tool.

[0007] In accordance with the invention, there is provided a downhole tool for submerging into a casing, the tool comprising: a tool housing having an outer surface, a first end and a second end, and having a longitudinal extension having a longitudinal axis, a moveable tool part, where in a first operational position the moveable tool part is in a first position relative to the tool housing, and in a second operational position the moveable tool part is in a second position relative to the tool housing, where in the first operational position the moveable tool part is in a different position relative to the outer surface, the first end or the second end than in the second operational position, an actuator configured to move the moveable tool part from its first operational position to its second operational position and vice versa, a resistive sensor, having a variable resistor, where a first part of the resistive sensor is coupled to a moveable element of the tool, the moveable element is configured to allow movement of the moveable tool part and a second part of the resistive sensor is coupled to the tool housing, and where the movement of the moveable element is configured to change the resistance of the variable resistor to register the position of the moveable tool part relative to the tool housing.

[0008] The use of a resistive sensor means the measurements made are made using a mechanical movement of a first part of the sensor relative to the second part of the sensor, or vice versa, where the mechanical movement changes the size of the variable resistor, which results in a change in the output of the signal, where the output represents the position of the first part relative to the second part. E.g. when the first part is moved in a direction away from the second part, the size of the resistance increases, or vice versa.

[0009] By using a variable resistor, it is possible to reduce the need or to eliminate the need to calibrate the sensor, so that if the tool is submerged into a borehole and is used on more than one downhole operation, there is no need to retrieve the tool to the surface after the first operation to calibrate or reset the sensor, meaning that the tool may be deployed for a second or a subsequent downhole operation without need for calibration, as the size of the variable resistance does not change during use. During an operation several kilometres down a well, the power often varies or is even lost so that the electric equipment has to restart. Before intervening the well, the tool is dressed up, and electric equipment such as sensors, is calibrated, and if power is lost, the sensors may lose their reference points. By using a variable resistor, the sensor is able to give the correct position of the movable part even though power is lost as the resistance is not changed during such power stop, and the sensor measures the resistance which corresponds to a certain position and movement of the movable part.

[0010] The tool housing may have a first housing part and a second housing part, and the first housing part may be a stationary housing part.

[0011] In addition, the moveable tool part may be part of the second housing part which is movable of the second housing part.

[0012] Furthermore, the moveable tool part may be a centre part.

[0013] The resistive sensor may be a resistive position sensor, where the resistive position sensor is configured to sense the distance between the first part of the resistive sensor and the second part of the resistive sensor, or it may be configured to sense a change in distance of the first part of the resistive sensor relative to the second part of the resistive sensor.

[0014] Moreover, the first part of the sensor may be seen as a moveable part of the sensor, where the second part of the sensor may be seen as a stationary part of the sensor. The moveable part of the sensor may move relative to the stationary part of the sensor, and the movement of the moveable part of the sensor causes the variable resistance of the resistive sensor to change, thereby changing an output of the sensor, which represents the position of the first part of the sensor relative to the second part of the sensor. The stationary part of the sensor, i.e. the second part of the sensor, may be mechanically connected to the tool housing, and the moveable part of the sensor, i.e. the first part of the sensor, may be mechanically connected to a moveable part of the tool or may be mechanically connected to intermediate part of the tool which is configured to move the moveable part of the tool.

[0015] Furthermore, the moveable element may be in mechanical communication with the moveable tool part. The moveable element may e.g. be in the form of intermediate part, or two or more intermediate parts that connect the actuator with the moveable tool part. A first end of the moveable element may be connected to the actuator, and a second end of the moveable element may be connected to the moveable tool part.

[0016] Additionally, , the moveable element may be part of the moveable tool part. Thus, the moveable element may be part of the moveable tool part, where the moveable tool part may be e.g. pivotally connected to the tool housing, where the moveable element is on one side of the pivotal connection and the engagement part of the moveable tool part may be on an opposite side of the pivotal connection, so that movement of the moveable tool part causes the engagement part of the moveable tool part to move in a direction towards or away from the tool housing. In other embodiments, the moveable tool part may be a connecting part of the moveable tool part, where the connecting part is connected to the actuator.

[0017] In addition, the sensor may comprise a sensor housing, where the sensor housing may be connected with the second part of the resistive sensor. The sensor housing may be connected with the tool housing, or a stationary part of the tool, allowing the first part of the sensor to be moved relative to the sensor housing. The sensor housing may be configured to provide protection to the mechanical and / or electric elements of the sensor, where the sensor housing may provide a liquid, gas and / or dust protection to the components of the sensor.

[0018] Moreover, the resistive sensor at a first length may have a first resistance and at a second length may have a second resistance, where the first resistance may be different from the second resistance. The length of the resistive sensor may be altered by moving a moveable sensor part relative to a stationary sensor part. The stationary sensor part may e.g. be a sensor housing, where the moveable sensor part may be a moveable part that may extend out of the housing in its second position and within the housing in its first position.

[0019] Furthermore, the resistive sensor may comprise a stationary sensor part and a moveable sensor part, where in a first position relative to each other has a first resistance and at a second position relative to each other has a second resistance, where the first resistance may be different from the second resistance, and where the first position may be different from the second position.

[0020] The variable resistor may be potentiometer, a linear potentiometer, rotational potentiometer, a resistive transducer, or any type of resistor that changes its resistance as a function of its length or distance from its first connector to its second connector. The variable resistor may be a slidable or a rotational potentiometer. A change in the value of resistance resulting in a change in length of the conductor can be used to measure displacement.

[0021] Additionally, the tool may comprise an electric motor and a pump, and the actuator may be a hydraulic actuator. The electric motor may be used to drive a pump, where the pump is used to provide hydraulic power to a hydraulic actuator. Furthermore, the electric motor may be utilised to rotate a first housing part of the downhole tool relative to a second housing part of the downhole tool or may be utilised to provide mechanical movement of a part of the downhole tool, such as a milling head.

[0022] Further, the downhole tool may comprise a stroking tool i.e. a stroker tool for providing an axial stroking movement along the longitudinal axis. The stroking tool is a hydraulic stroker configured to provide linear movement for moving an operational tool part along the longitudinal axis. The hydraulic stroker may be provided with a moveable element which may be configured to provide a force transmission between the stroker and the moveable tool part. The moveable element may be configured to move in a linear movement inside the tool body, where the force transmission is in a direction that is different from the linear movement of the moveable element. A direction different from the linear movement may be where the linear movement of the moveable element may transmit the force via e.g. the moveable tool part in a different direction, such as a radial direction.

[0023] Furthermore, the first housing part may be arranged to rotate relative to the second housing part. The first housing part may be in connection with a downhole anchor, where the downhole anchor ensures that the first housing part is fixed in position relative to the well tubular, while the second housing part is configured to rotate relative to the first housing part along a rotational axis that is coaxial or coincidental with the longitudinal axis of the tool housing. The moveable tool part may be connected with the second housing part, allowing the moveable tool part to rotate relative to the first housing part along with the second housing part.

[0024] In addition, the tool part may be a cutting arm, the cutting arm being moveable between a retracted position and a projected position in relation to the outer surface of the tool housing.

[0025] The cutting arm may be a cutting arm utilised to cut a well tubular using a rotational movement of the cutting arm, while the cutting arm provides a force in a radial direction (away from the longitudinal axis) into the well tubular. The rotational movement of the cutting arm allows the cutting arm to cut incrementally into the well tubular, while radial force of the cutting arm allows the cutting arm to increase the distance from the tool housing incrementally when the cutting arm cuts deeper into the well tubular.

[0026] The tool part may be a drilling bit for drilling a hole in the casing or well tubular.

[0027] Moreover, the downhole tool may be a tubing cutter, configured to separate a first part of a well tubular from a second part of a well tubular.

[0028] Additionally, the moveable element may be in connection with a hydraulic piston, where the hydraulic piston may be configured to move the moveable tool part from its first operational position to its second operational position.

[0029] The hydraulic piston may be driven by a hydraulic pump which may be driven by a motor.

[0030] The drilling bit may be projected radially from the tool housing by the hydraulic piston, the movable element being connected to the hydraulic piston.

[0031] Further, the moveable tool part may be configured to move from its first operational position to its second operational position in a radial direction or a longitudinal direction. Within the context of the present disclosure, a radial direction may be a direction that is perpendicular to the longitudinal axis of the downhole tool, while the longitudinal direction may be a direction that is parallel and / or coaxial with the longitudinal axis of the downhole tool.

[0032] The first operational position of the moveable tool part may be where the moveable tool part is in a retracted position, and the second operational position may be where the moveable tool part is in an extended position. The retracted position may e.g. be where the moveable tool part is aligned with the part of the well tubular or an obstacle in the well tubular, which is to be cut, drilled or milled, and where the extended position may be when the moveable tool part has cut or drill through the well tubular or where a milling head has performed milling operation and is extended through the obstacle in the well tubular.

[0033] In addition, the variable resistor may be a linear resistor being linearly correlated with the distance from the first part of the resistive sensor and to the second part of the resistive sensor. The linear resistor may be arranged in such a way that the linear resistor has a predefined scope of movement, where each unit of increment represents a predefined amount of movement of the moveable element and / or the moveable tool part. Thus, when the variable resistor is moved a predefined distance on a first part of the variable resistor, and the variable resistor is moved the same distance on a second part of the variable resistor, the change in resistance across the first part is the same across the second part.

[0034] Moreover, the downhole tool may be a wireline downhole tool. The wireline downhole tool may be provided with electric power and data transfer via the wireline, where the electric power is utilised to power the downhole tool, and the data transfer may be utilised to control the downhole tool and to send electric signals representing the position of the moveable tool part to a surface control unit.

[0035] Furthermore, the resistive sensor may provide a first electrical signal output that correlates with the position of the moveable tool part. This means that when the moveable tool part moves a predefined distance, the first electrical signal output represents the position of the moveable tool part during the movement. The electrical signal may be transferred to a downhole controller, where the downhole controller may be utilised to provide a control signal to the actuator to provide control of the moveable tool part. Thus, the first electrical signal output may be utilised in a feedback loop to register and confirm the movement of the moveable tool part and allow the downhole controller to provide control signals to ensure that the moveable tool part performs the predefined downhole operation and to ensure that the downhole operation has been completed before the downhole tool is moved to a different downhole position, or before the downhole tool is utilised for a second downhole operation.Brief description of the drawings

[0036] The following is an explanation of exemplary embodiments with reference to the drawings, in which: Fig. 1 is a sectional view of a submerged downhole tool in a first operational position, Fig. 2 is a sectional view of a submerged downhole tool in a second operational position, Fig. 3 is a sectional view of a resistive sensor in accordance with the present disclosure, Fig. 4 is a sectional view of a tubing puncher having a resistive sensor in accordance with the present disclosure, Fig. 5 is a sectional view of one stroker tool having a resistive sensor in accordance with the present disclosure, and Fig. 6 is a sectional view of another stroker tool having a resistive sensor in accordance with the present disclosure. Detailed description

[0037] Various exemplary embodiments and details are described hereinafter, with reference to the figures when relevant. It should be noted that the figures may or may not be drawn to scale and that elements of similar structures or functions are represented by like reference numerals throughout the figures. It should also be noted that the figures are only intended to facilitate the description of the embodiments. They are not intended as an exhaustive description of the disclosure or as a limitation on the scope of the disclosure. In addition, an illustrated embodiment needs not have all the aspects or advantages shown. An aspect or an advantage described in conjunction with a particular embodiment is not necessarily limited to that embodiment and can be practiced in any other embodiments even if not so illustrated, or if not so explicitly described.

[0038] Fig. 1 shows a sectional schematical view of a downhole tool 1 that is submerged in a casing 3 in accordance with the present disclosure. The tool 1 comprises a tool housing 5 having an outer surface 7, a first end 9 and a second end 11, and having a longitudinal extension having a longitudinal axis A. The downhole tool 1 comprises a moveable tool part 13, which in this embodiment is one or more cutting arms 15, where in a first operational position, the cutting arm 15 is in a first position relative to the tool housing 5, i.e. in a retracted position, as shown in Fig. 1, and in a second operational position the moveable tool part 13, i.e. the cutting arm 15 is in a second position relative to the tool housing 5, i.e. in an extended position, as shown in Fig. 2. The moveable tool part 13 is in the first operational position in a different position relative to the outer surface 7, the first end 9 or the second end 11 than in the second operational position.

[0039] The downhole tool 1 may be a downhole wireline tool that comprises a wireline 17 powering a motor 19, a pump 21 driven directly or indirectly by the motor 19 for delivering a flow of fluid to an actuator 23, which may be in the form of a hydraulic piston 25, which is actuated by the fluid delivered by the pump 21. The actuator 23 is configured to move the moveable tool part 13 from its first operational position to its second operational position and vice versa. The downhole tool 1 further comprises a downhole anchor section 27 configured to anchor the tool 1 inside the casing when a downhole operation is to be performed and to fix the position of the downhole tool 1 in a longitudinal direction of the casing 3, in a rotational direction or in a radial direction. The anchor section 27 comprises one or more anchor elements 29, which may be retracted during the submersion of the tool 1 into the casing 3 and extended in a radial outwards direction towards an inner surface 31 of the casing to anchor the downhole tool 1 relative to the casing 3.

[0040] The actuator 23 may be connected to a moveable element 33, where the moveable element 33 is in mechanical communication with the moveable tool part 15, where a movement of the moveable element 33 in a longitudinal direction (along the longitudinal axis A) in a direction towards the first end 9 causes the moveable tool part 15 to move from its first operational position to its second operational position, and where a movement of the moveable element 33 in a longitudinal direction (along the longitudinal axis A) in a direction towards the second end 11 causes the moveable tool part 15 to move from its second operational position to its first operational position. The moveable element 33 may be part of the moveable tool part 15 or may be a separate element that abuts the moveable tool part 15 to move it from its first operational position to its second operational position, or vice versa.

[0041] The downhole tool may further comprise a resistive sensor 35, where the resistive sensor may have a variable resistor 43, where a first part 37 of the resistive sensor 35 is coupled to the moveable element 33 of the downhole tool 1, the moveable element 33 and a second part 39 of the resistive sensor 35 is coupled to the tool housing 5, or a stationary part 41 of the tool housing 5, and where the movement of the moveable element 33 is configured to change the resistance of the variable resistor 43 to register the position of the moveable tool part 15 relative to the tool housing 5. The first part 37 of the resistive sensor 35 may be coupled to the moveable element 33 via a coupling connector 45, which extends from the first part 37 towards the moveable element 33.

[0042] In the embodiment shown in Fig. 1 and Fig. 2, the resistive sensor 35 comprises a variable resistor 43 which changes resistance by moving a first sensor part 47 relative a second sensor part 49 in a linear movement parallel to the longitudinal axis A. In the first operational state, the first sensor part 47 may be in a retracted position, as shown in Fig. 1, where the variable resistor has a first resistive value, and in a second operational state the first sensor part may be in an extended position, as shown in Fig. 2, where the variable resistor has a second resistive value different from the first resistive value, and where the resistive sensor 35 has a first electrical output that reflects the position of the first sensor part 47 relative to the second sensor part 49. As the first sensor part 47 is coupled to the moveable element 33, the movement of the moveable element 33 and therefore the moveable tool part 15 causes a movement of the first sensor part 47 relative to the second sensor part 49, which means that he resistive sensor 35 can register the position of the moveable tool part 15 relative to the tool housing 5.

[0043] By using a variable resistor, it is possible to reduce or eliminate the need to calibrate the sensor, so that if the tool is submerged into a borehole and is used on more than one downhole operation, there is no need to retrieve the tool to the surface after the first operation to calibrate or reset the sensor, meaning that the tool may be deployed for a second or a subsequent downhole operation without need for calibration, as the size of the variable resistance does not change during use. Furthermore, during an operation several kilometres down a well, the power often varies or is even lost so that the electric equipment has to restart. Before intervening the well, the tool is dressed up and electric equipment, such as sensors, is calibrated, and if power is lost, the sensors may lose their reference points. By using a variable resistor, the sensor is able to give the correct position of the movable part even though power is lost as the resistance is not changed during such power stop, and the sensor measures the resistance which correspond to a certain position and movement of the movable part.

[0044] The downhole tool 1 may further comprise a motor 51 and a gearbox 53 configured to rotate the moveable tool part 15 along a rotational axis that is coaxial or coincidental with the longitudinal axis A of the downhole tool 1. The moveable tool part may be connected with a rotatable part 55, which is configured to rotate relative to the other parts of the tool housing 5 and allow the moveable tool part 15 to cut into the casing, as shown in Fig. 2.

[0045] Fig. 3 shows a resistive sensor 35 (as shown in Fig. 1 and 2), having a sensor housing 65, where the resistive sensor may have a variable resistor 43, where a first part 37 of the resistive sensor 35 is coupled to the moveable element 33 (as seen in Figs. 1 and 2) of the downhole tool 1, the moveable element 33 and a second part 39 of the resistive sensor 35 is configured to be coupled to the tool housing 5 or a stationary part 41 of the tool housing 5 (seen in Fig. 1 and 2), and where a movement of the moveable element 33 is configured to change the resistance of the variable resistor 43 to register the position of the moveable tool part 15 relative to the tool housing 5. The first part 37 of the resistive sensor 35 may be configured to move in a direction shown by arrow B, where each incremental movement of the first part 37 may change the size of the variable resistor 43. The resistive sensor may have a first electrical input 57, and a first electrical output 59, as well as a ground 61. The resistive sensor 35 may be provided with a first predefined voltage via the first electrical input 57, where the size of the variable resistor 43 determines the voltage of the output electrical signal registered from the first electrical output 59. Thus, the movement of the first part 37 of the resistive sensor, relative to the second part 39 of the resistive sensor, will cause a change in the size of the variable resistor and thereby provide an electrical signal that represents the position of the first part 37 relative to the second part 39.

[0046] The resistive sensor may e.g. be a sensor where the variable resistance may function by moving a slider across a full length of a resistor. The input supply voltage is applied to the entire length of the resistor. The output voltage is measured as voltage drop between the fixed and the movable contact. The slider may be adjusted manually over the resistive strip to change the resistance value from zero to a higher value. When the resistance changes, the current flowing through circuit changes. Thus, the mechanical movement of the slider may be obtained by a mechanical movement of a moveable tool part, where the position of the slider represents the position of the moveable tool part.

[0047] The variable resistor 43 may comprise a first sensor part 47, and a second sensor part 49, where the first sensor part 47 may be configured to be moved relative to the second sensor part 49, thereby altering the resistance of the variable resistor 43. The resistive sensor 35 may further comprise at least one resilient member 63, such as a leaf spring, made out of a conductive material, where the resilient member 63 comprises a first resilient arm 65 and a second resilient arm 67, where the first and the second resilient arms provide a resilient force in a direction towards a first conductive part 69 and a second conductive part 71, ensuring that the resilient member 63 provides an electrical conduction connection between the first conductive part 69 and the second conductive part 71. The movement of the resilient member 63 in an axial direction (shown by arrow B) together with the first sensor part 47 changes the size of the variable resistor 43, where the movement represents the movement of the moveable tool part (as seen in Fig. 1). The first conductive part 69 and / or the second conductive part 71 may be a first electrical circuit board 69 and a second electrical circuit board 71, where the circuit boards may be parts of the variable resistor 43. Thus movement of the resilient member along the circuit boards may alter the variable resistance, and provide a sensor output.

[0048] Fig. 4 shows a downhole tool 101, as disclosed in WO 2017 / 211825, in a first operating state where the downhole tool may comprise a tool part 103, such as a drilling bit, capable of being projected out of a tool housing 105 using a projection piston 107 / hydraulic piston configured to push the tool part 103 in a radial direction towards a casing (not shown) or another well tubular. The downhole tool comprises a retraction piston 109 connected to the projection piston 107 via an elongated element 108, so that when the projection piston 107 is pushed in a radial direction outwards, the retraction piston 109 moves in an axial direction and compresses a spring element 111, where the axial movement of the retraction piston 109 corresponds to the radial movement of the tool part 103. The downhole tool may comprise a resistive sensor 113 in accordance with the present disclosure, where a second part 115 of the resistive sensor 113 may be connected to a tool body 117 of the downhole tool, and a first part 119 of the resistive sensor may be connected to the retraction piston 109 via a connecting part 121, so that the movement of the retraction piston moves the first part 119 of the resistive sensor 113 relative to the second part 115 of the resistive sensor 113, and where the movement changes the size of the variable resistor (not shown) of the resistive sensor 113, which thereby senses the radial position of the tool part 103, where the output of the resistive sensor 113 reflects the position of the tool part 103.

[0049] Fig. 5 shows a stroker tool 201, also called a stroking tool for providing an stroking force along a tool axis for e.g. pulling a plug, as disclosed in WO 2008 / 128543, in a second operating state where the stroker tool 201 comprises a housing 207 and a piston 203provided around a shaft 205 so that the shaft 205 may run back and forth within the housing 207 for providing an axial force. The stroker tool 201 may be driven by a motor (not shown) which drives a pump (not shown), where the pump pumps fluid into a first chamber 209 by sucking a corresponding amount of fluid from a second chamber 211. Thus, the piston 203 and, consequently, the shaft 205 are driven forward and backward providing an axial force in both directions. The second chamber 211 may be separated from the remaining part of the tool 201 by a stationary wall 213, where the shaft 205 extends through the stationary wall 213, and where the shaft has a moveable part 214, which is fixedly connected with the shaft 205.

[0050] The stroker tool 201 may comprise a resistive sensor 215 in accordance with the present disclosure, where a second part 217 of the resistive sensor 215 may be connected to the stationary wall 213 and a first part 219 of the resistive sensor 215 may be connected to the moveable part 215 via a connecting part 221, so that the movement of the moveable part 214, i.e. the piston 214, moves the first part 219 of the resistive sensor 215 relative to the second part 217 of the resistive sensor 215, and where the movement changes the size of variable resistor (not shown) of the resistive sensor 215, which thereby senses the radial position of the shaft 205, where the output of the resistive sensor 215 reflects the position of the tool part shaft. The shaft 205 may be connected to a moveable tool part (not shown), where the movement of the shaft 205 causes a movement of the moveable tool part in a direction towards and away from the downhole tool (as seen in e.g. Fig. 1), or in an axial direction.

[0051] Fig. 6 shows a downhole stroking tool 301, as disclosed in WO 2016 / 139264, in a second operating state for providing an axial force in an axial direction of the tool 301, which is also the axial direction of a well, e.g. to pull a plug and a casing. The downhole stroking tool 301 comprises a housing 303, a first chamber 305 inside the tool, and a first tool part 307 comprising a pump unit 319 for providing pressurised fluid to the chamber 305. The downhole stroking tool 301 may further comprise an electrical motor (not shown) and an electronic section (not shown) for controlling the function of the tool. The downhole stroking tool 301 comprises a shaft 309 penetrating the chamber 305 and a first piston 311 dividing the chamber into a first chamber section 313 and a second chamber section 315. The piston 311 is fixedly attached to a second tool part 321, where the pressurisation of the first chamber section 313 generates a pressure on the piston 311 and a downstroke movement so that the second tool part 321 slides relative to a tool body 317, separating the pump unit 319 from the slidable second tool part 321 and extending the second tool part 321 in an axial direction away from the pump unit 319. Thus the second tool part 321 is a movable housing part that is moveable relative to the stationary tool body 317.

[0052] The downhole stroker tool 301 may comprise a resistive sensor 329 in accordance with the present disclosure, where a second part 323 of the resistive sensor 329 may be connected to the body 317 and a first part 325 of the resistive sensor 329 may be connected to the moveable part, i.e. the piston 311 and the second tool part 321 (the movable tool housing part) via a connecting part 327, so that the movement of the moveable part 317, i.e. the piston, moves the first part 325 of the resistive sensor 329 relative to the second part 323 of the resistive sensor 329, and where the movement changes the size of variable resistor (not shown) of the resistive sensor 329, which thereby senses the axial position of the second tool part 321, where the output of the resistive sensor 329 reflects the position second tool part 321. The second tool part 321 may be connected to a moveable tool part (not shown), where the movement of the second tool part 321 causes a movement of the moveable tool part in a direction towards and away from the downhole tool in a radial direction (as seen in e.g. Fig. 1), or in an axial direction.

[0053] The use of the terms "first", "second", "third" and "fourth", "primary", "secondary", "tertiary" etc. does not imply any particular order, but are included to identify individual elements. Moreover, the use of the terms "first", "second", "third" and "fourth", "primary", "secondary", "tertiary" etc. does not denote any order or importance, but rather the terms "first", "second", "third" and "fourth", "primary", "secondary", "tertiary" etc. are used to distinguish one element from another. Note that the words "first", "second", "third" and "fourth", "primary", "secondary", "tertiary" etc. are used here and elsewhere for labelling purposes only and are not intended to denote any specific spatial or temporal ordering.

[0054] Furthermore, the labelling of a first element does not imply the presence of a second element and vice versa.

[0055] It is to be noted that the word "comprising" does not necessarily exclude the presence of other elements or steps than those listed.

[0056] It is to be noted that the words "a" or "an" preceding an element do not exclude the presence of a plurality of such elements.

[0057] It should further be noted that any reference signs do not limit the scope of the claims.

[0058] Although features have been shown and described, it will be understood that they are not intended to limit the claimed invention, and it will be made obvious to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the claimed invention. The specification and drawings are, accordingly, to be regarded in an illustrative rather than restrictive sense. The claimed invention is intended to cover all alternatives, modifications, and equivalents.

Claims

1. A downhole tool for submerging into a casing, the tool comprising: - a tool housing having an outer surface, a first end and a second end, and a longitudinal extension having a longitudinal axis, - a moveable tool part, where in a first operational position the moveable tool part is in a first position relative to the tool housing, and in a second operational position the moveable tool part is in a second position relative to the tool housing, where in the first operational position the moveable tool part is in a different position relative to the outer surface, the first end or the second end than in the second operational position, - an actuator configured to move the moveable tool part from the first operational position to the second operational position and vice versa, and - a resistive sensor, having a variable resistor, where a first part of the resistive sensor is coupled to a moveable element of the tool, the moveable element is configured to allow movement of the moveable tool part and a second part of the resistive sensor is coupled to the tool housing, and where the movement of the moveable element is configured to change the resistance of the variable resistor to register the position of the moveable tool part relative to the tool housing.

2. A downhole tool in accordance with claim 1, wherein the moveable element is in mechanical communication with the moveable tool part.

3. A downhole tool in accordance with any of the preceding claims, wherein the moveable element is part of the moveable tool part.

4. A downhole tool in accordance with any of the preceding claims, wherein the sensor comprises a sensor housing, where the sensor housing is connected with the second part of the resistive sensor.

5. A downhole tool in accordance with any of the preceding claims, wherein the resistive sensor at a first length has a first resistance, and at a second length has a second resistance, where the first resistance is different from the second resistance.

6. A downhole tool in accordance with any of the preceding claims, wherein the tool comprises an electric motor, a pump and where the actuator is a hydraulic actuator.

7. A downhole tool in accordance with any of the preceding claims, the downhole tool comprises a stroker, where the stroker is a hydraulic stroker configured to provide linear movement inside the tool body.

8. A downhole tool in accordance with any of the preceding claims, wherein the tool housing has a first housing part and a second housing part, where the first housing part is arranged to rotate or move along the longitudinal axis relative to the second housing part.

9. A downhole tool in accordance with any of the preceding claims, wherein the tool part is a cutting arm being moveable between a retracted position and a projected position in relation to the outer surface of the tool housing,10. A downhole tool in accordance with any of the preceding claims, wherein the downhole tool is a tubing cutter, configured to separate a first part of a well tubular from a second part of a well tubular.

11. A downhole tool in accordance with any of the preceding claims, wherein the moveable element is in connection with a hydraulic piston, where the hydraulic piston is configured to move the moveable tool part from the first operational position to the second operational position.

12. A downhole tool in accordance with any of the preceding claims, wherein the moveable tool part is configured to move from the first operational position to the second operational position in a radial direction or a longitudinal direction.

13. A downhole tool in accordance with any of the preceding claims, wherein the variable resistor is a linear resistor being linearly correlated with the distance from the first part of the resistive sensor and to the second part of the resistive sensor.

14. A downhole tool in accordance with any of the preceding claims, wherein the downhole tool is a wireline downhole tool.

15. A downhole tool in accordance with any of the preceding claims, wherein the resistive sensor provides a first electrical signal output that correlates with the position of the moveable tool part.

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