Downhole drilling tool cutting depth measuring device, depth measuring short section and measuring method

Abstract

The present invention provides a downhole drilling tool cutting depth measuring device, a depth measuring short section and a measuring method, wherein the measuring device comprises a first measuring unit, a second measuring unit, a lifting rope, a signal sensing unit and a control unit, the first measuring unit comprises a measuring short section and a plurality of casing hoops, the casing hoops are installed at the connection between downhole pipe strings, the measuring short section comprises a magnetic body, a coil and a coil skeleton, the coil and the coil skeleton are both located in the magnetic field generated by the magnetic body, the coil is connected to the signal sensing unit and the control unit, the coil can generate an alternating current signal and transmit it to the signal sensing unit and the control unit; the second measuring unit comprises a roller and a counter, the lower end of the lifting rope is connected to the measuring short section after passing around the roller, and the roller can be driven to roll synchronously when lowered, and the counter can measure the number of rotations of the roller when the lifting rope is lowered; the control unit can calculate the lowering depth of the measuring short section and control the lowering action of the measuring short section. The present invention has a simple structure, high operating efficiency and high measurement accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of detection of the lowering depth of a downhole cutting device in an oil and gas well, and in particular to a downhole drilling tool cutting depth measuring device, a depth measuring pup joint and a measuring method. Background Art

[0002] When cutting downhole tubulars, it is necessary to first measure the depth of the location to be cut, then lower the cutting device into the well, control the jet port of the cutting device to reach the location to be cut, and perform precise cutting to ensure that the problematic pipe in the tubular is cut.

[0003] In traditional technology, the detection of the lowering depth of the cutting device is to measure the length of the lowering rope in real time. This method has a large error. Due to the development of science and technology, various sensors for measuring downhole depth have emerged. Due to the presence of mud and other interfering substances in the pipe string and the great downhole depth, the sensor may be interfered during measurement, resulting in unreliable downhole depth measurement results.

[0004] In actual drilling operations, the downhole pipe string needs to be assembled with several iron spliced ​​pipes and supported deep in the well, and the spliced ​​pipes are connected with iron casing hoops. Therefore, a new technical solution can be used to count the number of spliced ​​pipes by utilizing the difference in wall thickness of the spliced ​​pipes and the wall thickness at the connection of the spliced ​​pipes, thereby obtaining the lowering depth of the cutting device. Summary of the invention

[0005] The purpose of the present invention is to solve at least one of the above-mentioned deficiencies in the prior art. For example, one of the purposes of the present invention is to provide a downhole drilling tool cutting depth measuring device, a depth measuring nipple and a measuring method, which avoids the problem in the prior art that the measuring sensor is easily disturbed and causes large measurement errors, and realizes efficient and accurate measurement of the downhole drilling tool cutting depth.

[0006] In order to achieve the above-mentioned object, the present invention provides a downhole drilling tool cutting depth measuring device on one hand, comprising a first measuring unit, a second measuring unit, a suspension rope, a signal sensing unit and a control unit, wherein the first measuring unit comprises a measuring short section and a plurality of casing collars, the casing collars are installed at the connection between downhole pipe strings, the measuring short section comprises at least one group of magnetic bodies, coils and coil skeletons, the magnetic bodies and the coil skeletons are both arranged in the measuring short section, the coils are wound on the coil skeletons, the coils and the coil skeletons are both located in the magnetic field generated by the magnetic bodies, the coils are connected to the signal sensing unit, the signal sensing unit is connected to the control unit, the coils can generate an alternating current signal when the measuring short section passes through the casing collar and transmit it to the signal sensing unit and the control unit; the second measuring unit is arranged above the first measuring unit, comprising a roller and a counter, the suspension rope is connected to the measuring short section at the lower end after passing around the roller, the suspension rope can drive the roller to roll synchronously when being lowered, the counter is connected to the control unit, and the counter can measure the number of rotations of the roller when the suspension rope is lowered; the control unit can receive the electrical signals of the coil and the counter and calculate the lowering depth of the measuring short section, and control the lowering action of the measuring short section.

[0007] Optionally, the measuring short section may include a shell, a core shaft, a fixing, a coil frame, a coil and two groups of magnetic bodies, the core shaft is inserted into the shell and fixedly connected to the shell through fixings arranged at the upper and lower ends, the coil frame is sleeved outside the core shaft and axially located between the fixings at the upper and lower ends, the coil is wound on the coil frame, the two groups of magnetic bodies include a first group of magnetic bodies and a second group of magnetic bodies, the first group of magnetic bodies is sleeved outside the core shaft and axially located between the fixing at the upper end of the core shaft and the coil frame, and the second group of magnetic bodies is sleeved outside the core shaft and axially located between the coil frame and the fixing at the lower end of the core shaft.

[0008] Optionally, the first group of magnetic bodies and the second group of magnetic bodies may respectively include a plurality of magnets arranged axially side by side, a buffer pad is provided between two adjacent magnets in each group of magnetic bodies, and a collar is provided between each magnet and the shell.

[0009] Optionally, the measuring nipple may further include an isolation block, which is sleeved outside the core shaft and is axially located between the second group of magnetic bodies and a fixing member at the lower end of the core shaft.

[0010] Optionally, the measuring short section may further include a joint, which is installed at the upper end of the shell, and the joint is used to connect the lifting rope to fix the measuring short section to the lower end of the lifting rope.

[0011] Optionally, the second measuring unit may further include a bracket, the roller and the counter are mounted on the bracket, and the bracket is used to fix the relative positions of the roller and the counter so that the counter can accurately measure the number of rotations of the roller.

[0012] Optionally, a friction pad may be installed on the roller to increase the friction between the suspension rope and the roller so that the suspension rope and the roller keep moving synchronously.

[0013] On the other hand, the present invention provides a depth measuring short section, including at least one group of magnetic body, coil and coil frame, the magnetic body and coil frame are both arranged in the measuring short section, the coil is wound on the coil frame, the coil and the coil frame are both located in the magnetic field generated by the magnetic body, and the coil can generate alternating current in a changing magnetic field and be identified.

[0014] Optionally, the measuring short section may include a shell, a core shaft, a fixing, a coil frame, a coil and two groups of magnetic bodies, the core shaft is inserted into the shell and fixedly connected to the shell through fixings arranged at the upper and lower ends, the coil frame is sleeved outside the core shaft and axially located between the fixings at the upper and lower ends, the coil is wound on the coil frame, the two groups of magnetic bodies include a first group of magnetic bodies and a second group of magnetic bodies, the first group of magnetic bodies is sleeved outside the core shaft and axially located between the fixing at the upper end of the core shaft and the coil frame, and the second group of magnetic bodies is sleeved outside the core shaft and axially located between the coil frame and the fixing at the lower end of the core shaft.

[0015] Optionally, the first group of magnetic bodies and the second group of magnetic bodies may respectively include a plurality of magnets arranged axially side by side, a buffer pad is provided between two adjacent magnets in each group of magnetic bodies, and a ring is provided between each magnet and the shell to facilitate loading and unloading of the magnets and reduce wear of the magnets; the number of magnets in the first group of magnetic bodies and the second group of magnetic bodies may be the same or different.

[0016] Optionally, the measuring short section may also include an isolation block and a joint, wherein the isolation block is sleeved outside the core shaft and is axially located between the second group of magnetic bodies and the fixing part at the lower end of the core shaft; the joint is installed at the upper end of the shell, and the joint is used to connect the device above the measuring short section.

[0017] In another aspect, the present invention provides a method for measuring the cutting depth of a downhole drilling tool. The method adopts the downhole drilling tool cutting depth measuring device as described above to perform measurement. The method comprises using the first measuring unit to measure the number of occurrences of the alternating current signal n1, and transmitting n1 to the control unit through the signal sensing unit. The control unit calculates the first lowering depth m1 of the measuring sub according to the length L1 of the single-section pipe string, the distance L2 from the measuring sub to the injection port of the injection sub, and n1, where m1=n1×L1+L2;

[0018] The counter transmits the measured number of rotations of the roller n2 to the control unit, and the control unit calculates the second lowering depth m2 of the measuring short section according to the length L3 and n2 of the suspension rope when the roller rotates one circle, where m2=n2×L3;

[0019] The control unit calculates the total lowering depth M of the cutting device according to the first lowering depth m1 and the second lowering depth m2, where M=m1+m2.

[0020] Compared with the prior art, the beneficial effects of the present invention include the following:

[0021] The present invention utilizes the electromagnetic induction principle to detect the lowering depth of the cutting device. Since the wall thickness of the spliced ​​pipe is different from the wall thickness of the spliced ​​pipe connection, the coil located in the constant magnetic field will generate an alternating current signal when passing through the spliced ​​pipe connection. The electric signal sensor senses the alternating current signal, and finally the ground control terminal records the number of times the alternating current signal is generated, thereby obtaining how many spliced ​​pipes the depth measurement short section of the cutting device has passed through, calculating the total length of the spliced ​​pipe plus the distance from the depth measurement short section to the injection port of the injection short section, that is, the lowering depth of the injection port, thereby controlling the injection port to reach a suitable depth to spray high-temperature fireworks for cutting operation. The device of the present invention has a simple structure, a convenient operation method, high efficiency, and high measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The above and other objects and / or features of the present invention will become more apparent through the following description in conjunction with the accompanying drawings, in which:

[0023] Figure 1 A schematic diagram of a downhole drilling tool cutting depth measuring device according to an exemplary embodiment of the present invention is shown.

[0024] Figure 2 A schematic structural diagram of a measuring sub in a downhole drilling tool cutting depth measuring device according to an exemplary embodiment of the present invention is shown.

[0025] Figure 3 A schematic structural diagram of a second measuring unit in a downhole drilling tool cutting depth measuring device according to an exemplary embodiment of the present invention is shown.

[0026] Description of reference numerals:

[0027] 1-first measuring unit, 11-measuring short section, 111-joint, 112-fixing piece, 113-housing, 114-coil skeleton, 115-coil, 116-core shaft, 117-first group of magnetic bodies, 1171-magnet, 1172-buffer pad, 1173-ring, 118-second group of magnetic bodies, 119-isolating block, 12-casing section hoop;

[0028] 2-second measuring unit, 21-roller, 22-friction pad, 23-counter, 24-bracket;

[0029] 3-Lifting rope, 4-Casing. DETAILED DESCRIPTION

[0030] Hereinafter, a downhole drilling tool cutting depth measuring device, a depth measuring sub and a measuring method according to the present invention will be described in detail in conjunction with exemplary embodiments.

[0031] In the description of the present application, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present application.

[0032] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

[0033] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0034] In traditional technology, the detection of the lowering depth of the cutting device is to measure the length of the lowering rope in real time. This method has a large error. Due to the development of science and technology, various sensors for measuring downhole depth have emerged. Due to the presence of mud and other interfering substances in the pipe string, the sensor may be interfered during measurement, so the measurement result of the downhole depth is unreliable.

[0035] Based on this, the present invention provides a downhole drilling tool cutting depth measuring device, including a first measuring unit, a second measuring unit, a suspension rope, a signal sensing unit and a control unit, wherein the first measuring unit includes a measuring short section and a plurality of casing collars, the measuring short section includes at least one group of magnetic body, coil and coil frame, the magnetic body and the coil frame are both arranged in the measuring short section, the coil is wound on the coil frame, the coil and the coil frame are both located in the magnetic field generated by the magnetic body, the coil is connected to the signal sensing unit, and the signal sensing unit is connected to the control unit; the casing collar is installed at the connection between downhole pipe columns, the coil can generate an alternating current signal when the measuring short section passes through the casing collar and transmit it to the signal sensing unit and the control unit; the second measuring unit is arranged above the first measuring unit, including a roller and a counter, the lower end of the suspension rope is connected to the measuring short section after it passes around the roller, the suspension rope can drive the roller to roll synchronously when it is lowered, the counter is connected to the control unit, and the counter can measure the number of rotations of the roller when the suspension rope is lowered; the control unit can receive the electrical signals of the coil and the counter and calculate the lowering depth of the measuring short section, and control the lowering action of the measuring short section.

[0036] The present invention utilizes the electromagnetic induction principle to detect the lowering depth of the cutting device. Since the wall thickness of the spliced ​​pipe is different from the wall thickness of the spliced ​​pipe connection, the coil located in the constant magnetic field will generate an alternating current signal when passing through the spliced ​​pipe connection. The electric signal sensor senses the alternating current signal, and finally the ground control terminal records the number of times the alternating current signal is generated, thereby obtaining how many spliced ​​pipes the depth measurement short section of the cutting device has passed through, calculating the total length of the spliced ​​pipe plus the distance from the depth measurement short section to the injection port of the injection short section, that is, the lowering depth of the injection port, thereby controlling the injection port to reach a suitable depth to spray high-temperature fireworks for cutting operation. The device of the present invention has a simple structure, a convenient operation method, high efficiency, and high measurement accuracy.

[0037] Exemplary Embodiment 1

[0038] The present exemplary embodiment provides a downhole drilling tool cutting depth measuring device.

[0039] Figure 1 A schematic diagram of a downhole drilling tool cutting depth measuring device according to an exemplary embodiment of the present invention is shown. Figure 2 A schematic diagram showing the structure of a measuring sub in a downhole drilling tool cutting depth measuring device according to an exemplary embodiment of the present invention is shown. Figure 3 A schematic structural diagram of a second measuring unit in a downhole drilling tool cutting depth measuring device according to an exemplary embodiment of the present invention is shown.

[0040] like Figures 1 to 3As shown in , the downhole drilling tool cutting depth measuring device described in this exemplary embodiment may include a first measuring unit 1, a second measuring unit 2 and a suspension rope 3, a signal sensing unit and a control unit (not shown in the figure). Among them, the first measuring unit 1 is a rough measuring unit, and the rough measuring unit may include a measuring short section 11 and a casing collar 12. The second measuring unit 2 is a precise measuring unit. The suspension rope 3 may be connected to the upper end of the measuring short section 11 after passing through the precise measuring unit. The measuring short section 11 may be lowered into the casing 4 under the control of the suspension rope 3, and may also be lifted out of the casing 4 under the control of the suspension rope 3. That is to say, the measuring short section 11 may be lowered and lifted in the casing 4 under the control of the suspension rope 3.

[0041] In this embodiment, the measuring sub 11 may include a joint 111, a fixing 112, a shell 113, a coil skeleton 114, a coil 115, a mandrel 116, a first group of magnetic bodies 117, a second group of magnetic bodies 118 and an isolation block 119. The shell 113 is a hollow cylindrical structure, the lower end of the joint 111 is threadedly inserted into the upper end of the shell 113, and the joint 111 is used to connect with the suspension rope 3, so as to fix the downhole drilling tool cutting depth measuring device to the lower end of the suspension rope 3, but the present invention is not limited thereto, and the joint 111 and the shell 113 may also be fixedly connected in other ways such as welding and integral molding.

[0042] Optionally, the core shaft 116 can be inserted into the shell 113, and its axial direction can be consistent with the axial direction of the shell 113, and the upper end of the core shaft 116 can be located at the lower end of the joint 111; there are two fixing members 112, which are respectively sleeved on the outer walls of the upper and lower ends of the core shaft 116, and the fixing members 112 at the upper and lower ends of the core shaft 116 are simultaneously inserted into the shell 113, that is, the two fixing members 112 are located between the shell 113 and the core shaft 116 in the radial direction, and the outer walls of the two fixing members 112 are in contact with the inner wall of the shell 113. The inner walls of the two fixings 112 fit with the outer wall of the core shaft 116, and the core shaft 116 is fixedly connected to the shell 113 through the fixings 112 at the upper and lower ends. The core shaft 116 can maintain a fixed relative position with the shell 113 in the shell 113, but the present invention is not limited to this. The number of fixings 112 can also be 1, 3 or more, as long as the core shaft 116 can be fixed in the shell 113. The fixings 112 and the shell 113, the core shaft 116 can be fixed by different types of fixed connections such as threaded connection, expansion connection, etc.

[0043] Optionally, the outer diameter of the core shaft 116 is smaller than the inner diameter of the shell 113, and an annular accommodating cavity can be formed between the core shaft 116 and the shell 113, and the coil skeleton 114 is installed in the accommodating cavity. That is to say, the coil skeleton 114 is located between the shell 113 and the core shaft 116 in the radial direction, and at the same time, the coil skeleton 114 is located in the middle of the core shaft 116 in the axial direction, but the present invention is not limited to this. The coil skeleton 114 may also be located above or below the axis of the core shaft 116, as long as the coil skeleton 114 is installed in the said accommodating cavity.

[0044] Optionally, a coil 115 is wound around the coil skeleton 114, and the coil 115 is also located in the accommodating cavity. That is, the coil 115 is located between the shell 113 and the core shaft 116 in the radial direction. Both ends of the coil 115 can be connected to the signal sensing unit. The coil 115 is made of conductive material. Specifically, the coil 115 is a metal material, such as copper wire, steel wire, aluminum wire, etc., but the present invention is not limited to this. The coil 115 may also be a non-metallic material, such as graphite, etc., as long as the conductive function can be achieved.

[0045] In this embodiment, the measuring short section 11 may include two groups of magnetic bodies: a first group of magnetic bodies 117 and a second group of magnetic bodies 118. The first group of magnetic bodies 117 and the second group of magnetic bodies 118 are respectively located in the accommodating cavity and are located on the upper and lower sides of the coil skeleton 114 in the axial direction, so that the coil skeleton 114 and the coil 115 are placed in the magnetic field generated by the magnetic bodies. However, the present invention is not limited to this. The measuring short section 11 may also include 1 group, 3 groups or more groups of magnetic bodies, as long as the magnetic bodies contained in the measuring short section 11 can provide an effective magnetic field for the measuring short section 11.

[0046] Optionally, the first group of magnetic bodies 117 are located in the accommodating cavity. Specifically, the first group of magnetic bodies 117 are located between the shell 113 and the core shaft 116 in the radial direction, and between the fixing piece 112 at the upper end of the core shaft 116 and the coil frame 114 in the axial direction. The first group of magnetic bodies 117 is composed of 6 magnets 1171 stacked in the axial direction, and each of the 6 magnets 1171 is an annular structure and is sleeved outside the core shaft 116. Specifically, each of the 6 magnets 1171 is made of magnetic steel, but the present invention is not limited to this. The number of magnets 1171 in the first group of magnetic bodies 117 may also be a positive integer other than 6, and the material of the magnet 1171 may also be a magnetic material other than magnetic steel, such as a magnet.

[0047] Optionally, the first group of magnetic bodies 117 also includes 6 buffer pads 1172, each of the 6 buffer pads 1172 is located between two adjacent magnets 1171, and the buffer pads 1172 can separate two adjacent magnets 1171 to prevent the magnets 1171 from colliding with each other and being damaged, thereby facilitating the disassembly, assembly and replacement of the magnets 1171. However, the present invention is not limited to this. The number of buffer pads 1172 in the first group of magnetic bodies 117 can also be other positive integers other than 6, as long as it matches the number of magnets 1171 in the first group of magnetic bodies 117, that is, a buffer pad 1172 is provided between two adjacent magnets 1171.

[0048] Optionally, the first group of magnetic bodies 117 also includes 6 rings 1173, each of the 6 rings 1173 is mounted outside the 6 magnets 1171, and installing the rings 1173 on the magnets 1171 can facilitate the disassembly, assembly and replacement of the magnets 1171 and reduce the wear of the magnets 1171, but the present invention is not limited to this. The number of rings 1173 in the first group of magnetic bodies 117 can also be other positive integers except 6, as long as it matches the number of magnets 1171 in the first group of magnetic bodies 117, that is, each magnet 1171 is provided with a ring 1173.

[0049] In this embodiment, the second group of magnetic bodies 118 are located in the accommodating cavity. Specifically, the second group of magnetic bodies 118 are located between the shell 113 and the core shaft 116 in the radial direction, and between the fixing part 112 at the lower end of the core shaft 116 and the coil frame 114 in the axial direction. The second group of magnetic bodies 118 are composed of 6 magnets stacked in the axial direction, each of the 6 magnets is an annular structure, and is sleeved outside the core shaft 116. Specifically, each of the 6 magnets is made of magnetic steel, but the present invention is not limited to this. The number of magnets in the second group of magnetic bodies 118 can also be a positive integer other than 6, and the material of the magnet can also be other magnetic materials other than magnetic steel, such as magnets.

[0050] The second group of magnetic bodies 118 may also include 6 buffer pads, each of the 6 buffer pads is located between two adjacent magnets, and the buffer pads can separate the two adjacent magnets to prevent the magnets from colliding with each other and being damaged, thereby facilitating the disassembly, assembly and replacement of the magnets. However, the present invention is not limited to this. The number of buffer pads in the second group of magnetic bodies 118 may also be a positive integer other than 6, as long as it matches the number of magnets in the second group of magnetic bodies 118, that is, a buffer pad is provided between two adjacent magnets.

[0051] The second group of magnetic bodies 118 may also include 6 rings, each of the 6 rings is mounted outside the 6 magnets. Installing the rings on the magnets can facilitate the disassembly, assembly and replacement of the magnets and reduce the wear of the magnets, but the present invention is not limited to this. The number of rings in the second group of magnetic bodies 118 can also be a positive integer other than 6, as long as it matches the number of magnets in the second group of magnetic bodies 118, that is, each magnet is provided with a ring.

[0052] In this embodiment, the isolation block 119 is installed in the accommodating cavity. Specifically, the isolation block 119 is located between the shell 113 and the core shaft 116 in the radial direction, and between the fixing piece 112 at the lower end of the core shaft 116 and the second group of magnetic bodies 118 in the axial direction. The isolation block 119 can be used to limit the range of the magnetic field generated by the magnetic body to above it, so as to avoid the driving short section installed below the measuring short section 11 from being disturbed by the magnetic field, so as to improve the accuracy of the depth measurement. The isolation block 119 is made of non-magnetic material, specifically, copper, aluminum and their alloy materials, but the present invention is not limited to this. The isolation block 119 can also be made of other non-metallic materials such as silicon and carbon, as long as the range of the magnetic field generated by the magnetic body can be limited to above it.

[0053] In this embodiment, the casing joint hoop 12 can be installed outside the casing 4, sleeved on the outer wall of the casing 4, and at the same time located between two adjacent casings in the axial direction to connect the two adjacent casings. The material of the casing joint hoop 12 is a magnetic conductive material, such as iron or steel, but the present invention is not limited to this. The material of the casing joint hoop 12 can also be other magnetic conductive materials such as cobalt and nickel.

[0054] Since the casing joint hoop 12 is annular and has a certain wall thickness, when the casing joint hoop 12 connects two adjacent casings, the wall thickness at the connection is the wall thickness of the casing joint hoop + the wall thickness of the casing 4, that is, the wall thickness of the connection between the two adjacent casings is greater than the wall thickness of the casing 4. When the measuring short section 11 moves up and down in the casing 4 driven by the suspension rope 3 and passes through the connection between the two adjacent casings, that is, the casing joint hoop 12, the magnetic field generated by the magnetic body in the measuring short section 11 may change due to the change in wall thickness. The coil 115 located in the magnetic field generates an electromagnetic effect due to the change in the magnetic field, and an alternating current may be generated on the coil 115. The alternating current may be recognized by the signal sensing unit and transmitted to the control unit.

[0055] In this embodiment, the second measuring unit 2 is installed on the ground at the wellhead, that is, above the first measuring unit 1. The second measuring unit 2 includes a roller 21, a friction pad 22, a counter 23 and a bracket 24, wherein the roller 21 is installed on the bracket 24 through a connecting shaft, and the roller 21 can rotate around the connecting shaft. The lifting rope 3 passes around the roller 21 to lower the measuring short section 11 into the casing 4 in the well.

[0056] Optionally, a friction pad 22 is installed on the contact surface between the roller 21 and the suspension rope 3. The friction pad 22 is made of rubber material. The friction pad 22 can increase the friction between the suspension rope 3 and the roller 21, so that the suspension rope 3 and the roller 21 maintain synchronous movement and avoid slipping between the suspension rope 3 and the roller 21. However, the present invention is not limited to this. The material of the friction pad 22 can also be cast iron or other materials with a large surface friction coefficient, as long as it can ensure that the suspension rope 3 and the roller 21 maintain synchronous movement and avoid slipping.

[0057] Optionally, the counter 23 is mounted on the bracket 24 and is located on one side of the roller 21. The counter 23 can measure the number of rolling circles of the roller 21. The counter 23 is connected to the control unit and can transmit the measured number of rolling circles of the roller 21 to the control unit. However, the present invention is not limited to this. The setting position of the counter 23 can also be located at other positions of the bracket 24, as long as the function of measuring the number of rolling circles of the roller 21 can be realized.

[0058] The following describes in detail the measuring process of the downhole drilling tool cutting depth measuring device according to the exemplary embodiment:

[0059] One end of the lifting rope 3 is connected to the measuring short section 11 with the injection short section. After the lifting rope 3 passes around the roller 21, the measuring short section 11 and the injection short section are lowered into the casing 4 of the wellbore. As the measuring short section 11 continues to descend in the casing 4, when passing through the connection between two adjacent casings, that is, the casing joint hoop 12, the magnetic field generated by the magnetic body in the measuring short section 11 may change due to the change in wall thickness. The coil 115 located in the magnetic field generates an electromagnetic effect due to the change in the magnetic field, and an alternating current may be generated on the coil 115. The alternating current can be recognized by the signal sensing unit and transmitted to the control unit. The control unit can calculate the first lowering depth of the cutting device through the number of times the alternating current appears, the length of a single casing, and the distance from the measuring short section to the injection port of the injection short section.

[0060] When the measuring sub 11 and the jetting sub are lowered to the section of casing where cutting is required, the counter 23 starts to measure the number of rotations of the roller 21 when the last AC signal appears. After the cutting device reaches the position where cutting is required, the control unit controls the suspension rope 3 to stop the lowering operation. At the same time, the counter 23 transmits the number of rotations of the roller 21 to the control unit. The control unit can calculate the second lowering depth of the cutting device according to the number of rotations of the roller 21 and the length of the suspension rope 3 when the roller 21 rotates one circle. Finally, the total lowering depth of the cutting device can be calculated by the first lowering depth and the second lowering depth.

[0061] Exemplary Embodiment 2

[0062] The present exemplary embodiment provides a depth measurement sub.

[0063] like Figure 2 As shown in , the depth measurement sub described in this exemplary embodiment may include a joint 111, a fixing 112, a shell 113, a coil skeleton 114, a coil 115, a mandrel 116, a first group of magnetic bodies 117, a second group of magnetic bodies 118, and an isolation block 119. The shell 113 is a hollow cylindrical structure, the lower end of the joint 111 is threadedly inserted into the upper end of the shell 113, and the joint 111 is used to connect with the suspension rope, so as to fix the downhole drilling tool cutting depth measurement device to the lower end of the suspension rope, but the present invention is not limited thereto, and the joint 111 and the shell 113 may also be fixedly connected in other ways such as welding and integral molding.

[0064] Optionally, the core shaft 116 can be inserted into the shell 113, and its axial direction can be consistent with the axial direction of the shell 113, and the upper end of the core shaft 116 can be located at the lower end of the joint 111; there are two fixing members 112, which are respectively sleeved on the outer walls of the upper and lower ends of the core shaft 116, and the fixing members 112 at the upper and lower ends of the core shaft 116 are simultaneously inserted into the shell 113, that is, the two fixing members 112 are located between the shell 113 and the core shaft 116 in the radial direction, and the outer walls of the two fixing members 112 are in contact with the inner wall of the shell 113. The inner walls of the two fixings 112 fit with the outer wall of the core shaft 116, and the core shaft 116 is fixedly connected to the shell 113 through the fixings 112 at the upper and lower ends. The core shaft 116 can maintain a fixed relative position with the shell 113 in the shell 113, but the present invention is not limited to this. The number of fixings 112 can also be 1, 3 or more, as long as the core shaft 116 can be fixed in the shell 113. The fixings 112 and the shell 113, the core shaft 116 can be fixed by different types of fixed connections such as threaded connection, expansion connection, etc.

[0065] Optionally, the outer diameter of the core shaft 116 is smaller than the inner diameter of the shell 113, and an annular accommodating cavity can be formed between the core shaft 116 and the shell 113, and the coil skeleton 114 is installed in the accommodating cavity. That is to say, the coil skeleton 114 is located between the shell 113 and the core shaft 116 in the radial direction, and at the same time, the coil skeleton 114 is located in the middle of the core shaft 116 in the axial direction, but the present invention is not limited to this. The coil skeleton 114 may also be located above or below the axis of the core shaft 116, as long as the coil skeleton 114 is installed in the said accommodating cavity.

[0066] Optionally, a coil 115 is wound around the coil skeleton 114, and the coil 115 is also located in the accommodating cavity. That is, the coil 115 is located between the shell 113 and the core shaft 116 in the radial direction. Both ends of the coil 115 can be connected to the signal sensing unit. The coil 115 is made of conductive material. Specifically, the coil 115 is a metal material, such as copper wire, steel wire, aluminum wire, etc., but the present invention is not limited to this. The coil 115 may also be a non-metallic material, such as graphite, etc., as long as the conductive function can be achieved.

[0067] In this embodiment, the measuring short section 11 may include two groups of magnetic bodies: a first group of magnetic bodies 117 and a second group of magnetic bodies 118. The first group of magnetic bodies 117 and the second group of magnetic bodies 118 are respectively located in the accommodating cavity and are located on the upper and lower sides of the coil skeleton 114 in the axial direction, so that the coil skeleton 114 and the coil 115 are placed in the magnetic field generated by the magnetic bodies. However, the present invention is not limited to this. The measuring short section 11 may also include 1 group, 3 groups or more groups of magnetic bodies, as long as the magnetic bodies contained in the measuring short section 11 can provide an effective magnetic field for the measuring short section 11.

[0068] Optionally, the first group of magnetic bodies 117 are located in the accommodating cavity. Specifically, the first group of magnetic bodies 117 are located between the shell 113 and the core shaft 116 in the radial direction, and between the fixing piece 112 at the upper end of the core shaft 116 and the coil frame 114 in the axial direction. The first group of magnetic bodies 117 is composed of 6 magnets 1171 stacked in the axial direction, and each of the 6 magnets 1171 is an annular structure and is sleeved outside the core shaft 116. Specifically, each of the 6 magnets 1171 is made of magnetic steel, but the present invention is not limited to this. The number of magnets 1171 in the first group of magnetic bodies 117 may also be a positive integer other than 6, and the material of the magnet 1171 may also be a magnetic material other than magnetic steel, such as a magnet.

[0069] Optionally, the first group of magnetic bodies 117 also includes 6 buffer pads 1172, each of the 6 buffer pads 1172 is located between two adjacent magnets 1171, and the buffer pads 1172 can separate two adjacent magnets 1171 to prevent the magnets 1171 from colliding with each other and being damaged, thereby facilitating the disassembly, assembly and replacement of the magnets 1171. However, the present invention is not limited to this. The number of buffer pads 1172 in the first group of magnetic bodies 117 can also be other positive integers other than 6, as long as it matches the number of magnets 1171 in the first group of magnetic bodies 117, that is, a buffer pad 1172 is provided between two adjacent magnets 1171.

[0070] Optionally, the first group of magnetic bodies 117 also includes 6 rings 1173, each of the 6 rings 1173 is mounted outside the 6 magnets 1171, and installing the rings 1173 on the magnets 1171 can facilitate the disassembly, assembly and replacement of the magnets 1171 and reduce the wear of the magnets 1171, but the present invention is not limited to this. The number of rings 1173 in the first group of magnetic bodies 117 can also be other positive integers except 6, as long as it matches the number of magnets 1171 in the first group of magnetic bodies 117, that is, each magnet 1171 is provided with a ring 1173.

[0071] In this embodiment, the second group of magnetic bodies 118 are located in the accommodating cavity. Specifically, the second group of magnetic bodies 118 are located between the shell 113 and the core shaft 116 in the radial direction, and between the fixing part 112 at the lower end of the core shaft 116 and the coil frame 114 in the axial direction. The second group of magnetic bodies 118 are composed of 6 magnets stacked in the axial direction, each of the 6 magnets is an annular structure, and is sleeved outside the core shaft 116. Specifically, each of the 6 magnets is made of magnetic steel, but the present invention is not limited to this. The number of magnets in the second group of magnetic bodies 118 can also be a positive integer other than 6, and the material of the magnet can also be other magnetic materials other than magnetic steel, such as magnets.

[0072] Optionally, the second group of magnetic bodies 118 also includes 6 buffer pads, each of the 6 buffer pads is located between two adjacent magnets, and the buffer pads can separate the two adjacent magnets to prevent the magnets from colliding with each other and being damaged, thereby facilitating the disassembly, assembly and replacement of the magnets. However, the present invention is not limited to this. The number of buffer pads in the second group of magnetic bodies 118 can also be a positive integer other than 6, as long as it matches the number of magnets in the second group of magnetic bodies 118, that is, a buffer pad is provided between two adjacent magnets.

[0073] Optionally, the second group of magnetic bodies 118 also includes 6 rings, each of the 6 rings is mounted outside the 6 magnets, and installing the rings on the magnets can facilitate the disassembly, assembly and replacement of the magnets and reduce the wear of the magnets, but the present invention is not limited to this. The number of rings in the second group of magnetic bodies 118 can also be a positive integer other than 6, as long as it matches the number of magnets in the second group of magnetic bodies 118, that is, each magnet is provided with a ring.

[0074] In this embodiment, the isolation block 119 is installed in the accommodating cavity. Specifically, the isolation block 119 is located between the shell 113 and the core shaft 116 in the radial direction, and between the fixing piece 112 at the lower end of the core shaft 116 and the second group of magnetic bodies 118 in the axial direction. The isolation block 119 can be used to limit the range of the magnetic field generated by the magnetic body to above it, so as to avoid the driving short section installed below the measuring short section 11 from being disturbed by the magnetic field, so as to improve the accuracy of the depth measurement. The isolation block 119 is made of non-magnetic material, specifically, copper, aluminum and their alloy materials, but the present invention is not limited to this. The isolation block 119 can also be made of other non-metallic materials such as silicon and carbon, as long as the range of the magnetic field generated by the magnetic body can be limited to above it.

[0075] Exemplary Embodiment 3

[0076] This exemplary embodiment provides a method for measuring the cutting depth of a downhole drilling tool.

[0077] The downhole drilling tool cutting depth measurement method described in this exemplary embodiment applies the downhole drilling tool cutting depth measurement device described in exemplary embodiment 1.

[0078] The method for measuring the cutting depth of a downhole drilling tool according to the exemplary embodiment includes:

[0079] like Figures 1 to 3 As shown in the figure, one end of the lifting rope 3 is connected to the measuring short section 11 with the injection short section. After the lifting rope 3 passes around the roller 21, the measuring short section 11 and the injection short section are lowered into the casing 4 of the wellbore together. As the measuring short section 11 continues to descend in the casing 4, when passing through the connection between two adjacent casings, that is, the casing joint hoop 12, the magnetic field generated by the magnetic body in the measuring short section 11 may change due to the change in wall thickness. The coil 115 located in the magnetic field may generate an electromagnetic effect due to the change in the magnetic field, and an alternating current may be generated on the coil 115. The alternating current may be identified by the signal sensing unit and transmitted to the control unit. The control unit may calculate the first section lowering depth m1 of the cutting device through the number of times the alternating current appears n1, the length L1 of a single casing, and the distance L2 from the measuring short section to the injection port of the injection short section, where m1=n1×L1+L2.

[0080] When the measuring short section 11 and the injection short section are lowered to the section of the casing where the cutting operation is required, the counter 23 starts to measure the number of rolling circles of the roller 21 when the last AC signal appears. After the cutting device reaches the position where the cutting operation is required, the control unit controls the suspension rope 3 to stop the lowering operation. At the same time, the counter 23 transmits the number of rolling circles of the roller 21 to the control unit. The control unit can calculate the second section lowering depth m2 of the cutting device according to the number of rolling circles n2 of the roller 21 and the length L3 passed by the suspension rope 3 when the roller 21 rotates one circle, m2=n2×L3.

[0081] The control unit can further calculate the total lowering depth M of the cutting device through the first lowering depth and the second lowering depth, where M=m1+m2.

[0082] In summary, the present invention uses the principle of electromagnetic induction to detect the lowering depth of the cutting device. Since the wall thickness of the spliced ​​pipe is different from the wall thickness of the spliced ​​pipe connection, the coil located in the constant magnetic field will generate an AC signal when passing through the spliced ​​pipe connection. The electrical signal sensor senses the AC signal, and finally the ground control terminal records the number of times the AC signal is generated, so as to obtain how many spliced ​​pipes the depth measurement short section of the cutting device has passed, calculate the total length of the spliced ​​pipe plus the distance from the depth measurement short section to the injection port of the injection short section, that is, the depth of the injection port being lowered, so as to control the injection port to reach a suitable depth to spray high-temperature fireworks for cutting operation. The device of the present invention has a simple structure, a convenient operation method, high efficiency, and high measurement accuracy.

[0083] Although the present invention has been described above in conjunction with the exemplary embodiments and the accompanying drawings, it should be apparent to those skilled in the art that various modifications may be made to the above-described embodiments without departing from the spirit and scope of the claims.

Claims

1. A method for measuring the cutting depth of a downhole drilling tool, characterized in that: The measuring method adopts a downhole drilling tool cutting depth measuring device for measuring; The measuring device comprises a first measuring unit, a second measuring unit, a suspension rope, a signal sensing unit and a control unit, wherein: The first measuring unit includes a measuring short section and a plurality of casing hoops, the casing hoops are installed at the connection between the downhole pipe strings, the measuring short section includes a shell, a core shaft, a fixing part, a coil frame, a coil and two groups of magnetic bodies, the magnetic body and the coil frame are both arranged in the measuring short section, the coil and the coil frame are both located in the magnetic field generated by the magnetic body, the coil is connected to the signal sensing unit, the signal sensing unit is connected to the control unit, and the coil can generate an alternating current signal when the measuring short section passes through the casing hoops and transmit it to the signal sensing unit and the control unit; the core shaft is passed through the shell and fixedly connected to the shell through fixing parts arranged at the upper and lower ends, the coil frame is sleeved outside the core shaft and axially located between the fixing parts at the upper and lower ends, the coil is wound on the coil frame, the two groups of magnetic bodies include a first group of magnetic bodies and a second group of magnetic bodies, the first group of magnetic bodies is sleeved outside the core shaft and axially located between the fixing part at the upper end of the core shaft and the coil frame, and the second group of magnetic bodies is sleeved outside the core shaft and axially located between the fixing part at the lower end of the core shaft; The second measuring unit is arranged above the first measuring unit, and includes a roller and a counter. After the lifting rope passes around the roller, the lower end is connected to the measuring short section. When the lifting rope is lowered, it can drive the roller to roll synchronously. The counter is connected to the control unit, and the counter can measure the number of rotations of the roller when the lifting rope is lowered; The control unit can receive the electrical signals from the coil and the counter and calculate the lowering depth of the measuring short section, thereby controlling the lowering action of the measuring short section; The first group of magnetic bodies and the second group of magnetic bodies respectively include a plurality of magnets arranged axially side by side, a buffer pad is provided between two adjacent magnets in each group of magnetic bodies, and a collar is provided between each magnet and the shell; The measuring nipple further comprises an isolation block, which is sleeved outside the core shaft and axially located between the second group of magnetic bodies and a fixing member at the lower end of the core shaft; The measuring method comprises using the first measuring unit to measure the number of occurrences of the alternating current signal n1, and transmitting n1 to the control unit through the signal sensing unit, wherein the control unit calculates the first lowering depth m1 of the measuring sub according to the length L1 of the single-section pipe string, the distance L2 from the measuring sub to the injection port of the injection sub, and n1, where m1=n1×L1+L2; The counter transmits the measured number of rotations of the roller n2 to the control unit, and the control unit calculates the second lowering depth m2 of the measuring short section according to the length L3 and n2 of the suspension rope when the roller rotates one circle, where m2=n2×L3; The control unit calculates the total lowering depth M of the cutting device according to the first lowering depth m1 and the second lowering depth m2, where M=m1+m2.

2. The method for measuring the cutting depth of downhole drilling tools according to claim 1, characterized in that: The measuring short section also includes a joint, which is installed at the upper end of the shell, and the joint is used to connect the lifting rope to fix the measuring short section at the lower end of the lifting rope.

3. The method for measuring the cutting depth of downhole drilling tools according to claim 1, characterized in that: The second measuring unit also includes a bracket, and the roller and the counter are mounted on the bracket. The bracket is used to fix the relative positions of the roller and the counter so that the counter can accurately measure the number of rotations of the roller.

4. The method for measuring the cutting depth of downhole drilling tools according to claim 1, characterized in that: A friction pad is installed on the roller to increase the friction between the suspension rope and the roller so that the suspension rope and the roller keep moving synchronously.

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