Sensor for casing pipe screwing-on measurement

Abstract

The invention relates to oil field casing drilling, in particular to a sensor for casing screwing-on measurement, and aims to solve the problem that an error correction result is inaccurate due to the temperature difference between the placement position of a temperature sensor and the patch position of a strain gauge and the self measurement error of the temperature sensor. Through the arrangement of the PCB groove, the radio frequency antenna groove and the battery hole, the number of turns of thread rotation in the threaded connection process of casing drilling equipment and the torque generated during thread matching can be monitored at the same time, and the quality of threaded connection between the equipment is more effectively guaranteed. And the design of a Wheatstone bridge temperature compensation circuit can be completed according to the sensitivity of the negative temperature coefficient of the strain gauge and the resistance change of the positive temperature coefficient. Through the feedback mechanism of the compensation circuit, the reduction of the output voltage of the strain gauge Wheatstone bridge circuit caused by the temperature can be effectively compensated.

Description

Technical Field

[0001] The present invention relates to the technical field of oilfield casing drilling, and particularly to a sensor for measuring casing make-up. Background Art

[0002] Casing drilling technology refers to a drilling method in which a casing is directly used to replace the drill pipe to connect downhole drilling tools during the drilling process, and the casing is used to transmit torque, pressure, and hydraulics. This technology has significant advantages in the oil industry, such as significantly reducing the construction period and cost investment. However, the torsional capacity of the threads used in casing drilling is one of the key factors restricting its development, and the correct connection of casing thread joints is the key to the successful implementation of casing drilling. How to effectively ensure the number of make-up turns and the tightening degree of the threads during the connection of drilling casings is crucial for the safety, mobility, and long-term correct operation of the equipment. Therefore, in order to meet the development trend of precise control and intelligentization of drilling technology, a precise thread make-up torque and turn measurement device is a prerequisite for the application of new drilling technology in the market. In addition, the working conditions in the oil extraction field are complex, and most of the extraction environments face extreme weather conditions such as high temperature or extremely cold environments. The traditional torque measurement method integrated with a Wheatstone bridge is difficult to avoid the influence of temperature on the sensitivity of the strain gauge. Therefore, temperature compensation must be carried out during actual use. The currently commonly used solution is to install a temperature sensor near the strain gauge, and by collecting the ambient temperature signal in real time, the correction of the sensor acquisition error can be achieved through an algorithm at the upper computer end. However, the obvious defect of this strategy is that there is a temperature difference between the installation position of the temperature sensor and the strain gauge patch position, and the measurement error of the temperature sensor itself will also cause inaccurate error correction results. Therefore, a better way to compensate the temperature of the sensor is to compensate the temperature error of the sensor through hardware circuit design. Summary of the Invention

[0003] The purpose of the present invention is to provide a sensor for measuring casing make-up to solve the problems of temperature difference between the installation position of the temperature sensor and the strain gauge patch position, and inaccurate error correction results caused by the measurement error of the temperature sensor itself.

[0004] The present invention provides a sensor for measuring casing make-up, including a strain shaft. An explosion-proof housing is sleeved on the body of the strain shaft. Connecting threads are provided at both ends of the strain shaft extending out of the explosion-proof housing. A power supply module, a signal acquisition module, a wireless transceiver module, and a control module are provided inside the explosion-proof housing;

[0005] There is an annular space in the shape of a circle between the strain shaft and the explosion-proof housing. Strain gauges forming a Wheatstone bridge are attached to the body of the strain shaft and are located in this annular space.

[0006] Among them, the signal acquisition module includes a Wheatstone bridge temperature compensation circuit for strain signal acquisition and temperature compensation.

[0007] Further, the strain gauges of the Wheatstone bridge are uniformly distributed at an angle of 45° with respect to the central axis of the strain axis on the 360° strain axis body, and are alternately arranged at angles of 45° and 135° with respect to the axis baseline of the strain axis.

[0008] Further, the strain axis body is provided with an annular groove surface, and an annular space is formed with the inner wall of the explosion-proof housing;

[0009] Axial limit is achieved by the shaft shoulders on the strain axis and the flange on both sides of the explosion-proof housing.

[0010] Further, two sets of embedded measurement system channels are symmetrically arranged on the explosion-proof housing, and each set of channels includes a connected PCB slot, a radio frequency antenna slot, and a battery hole;

[0011] The PCB slot is connected to the battery hole through a through hole to lead out the battery wire, and is connected to the radio frequency antenna slot through another through hole for the signal wire;

[0012] A top cover and an antenna cover are respectively arranged on the PCB slot and the radio frequency antenna slot,

[0013] Among them, the battery is placed in the battery hole to form the power supply module, the wireless antenna is placed in the radio frequency antenna slot to form the wireless transceiver module, and the microcontroller is placed in the PCB slot to form the control module.

[0014] Further, a battery box and a battery box cover with a pull ring are provided in the battery hole, and a battery box upper bottom plate and a battery box lower bottom plate are provided at the bottom of the battery box; the pull ring is hinged in the groove at the end of the battery box cover for easy unfolding and folding,

[0015] Among them, a through hole is provided at the bottom of the battery box, and the battery box upper bottom plate and the battery box lower bottom plate are sequentially assembled at both ends of the through hole at the bottom of the battery box;

[0016] A battery cover is provided at the opening of the battery hole, a buckle is provided through the protruding section of the battery cover, and the folding surface of the buckle abuts against the axial end face of the explosion-proof housing to prevent the battery box from rotating. A through hole is horizontally provided on the protruding section of the battery cover, and an opening pin is inserted into the through hole. A gasket is sleeved on the battery box, and the gasket is located inside the opening pin. A rope buckle ring is provided on the outer side of the battery cover.

[0017] Further, a flange is sleeved on the strain axis. A plurality of first positioning grooves are arranged on one side of the flange facing the explosion-proof shell. Second positioning grooves corresponding to the first positioning grooves are arranged on the explosion-proof shell. A positioning pin is movably arranged in the space formed by the first positioning groove and the second positioning groove. A positioning hole extending outward is arranged on the groove wall of the first positioning groove. A fastening screw for pressing against the positioning pin is fitted in the positioning hole. A circular groove corresponding to the radial end of the positioning pin is arranged on the strain axis;

[0018] Fixing holes are formed on both sides of the first positioning groove. Connecting bolts for connecting with the explosion-proof shell are fitted in the fixing holes.

[0019] Further, two grooves are symmetrically arranged on the outer periphery of the explosion-proof shell. A battery hole extending along the same direction and a first through hole for communicating with the PCB groove are arranged on one side wall of the groove;

[0020] A processing hole for penetrating the RF antenna groove is arranged on the other side wall of the groove. The far side section of the processing hole forms a second through hole for communicating with the PCB groove. A large thread cover is arranged at the orifice end of the processing hole.

[0021] Further, the signal acquisition module integrates a three-axis gyroscope for collecting the number of thread fastening turns;

[0022] The signal acquisition module further includes an A / D conversion circuit and a temperature sensor, which are respectively used for analog-to-digital conversion of the Wheatstone bridge signal and real-time temperature measurement and alarm of the working area.

[0023] Further, the Wheatstone bridge temperature compensation circuit includes: differential operational amplifiers A1, A2, A3, pull-up resistors R1, R2, R3, R8, strain gauges Ra, Rb, Rc, Rd, resistors R6, R7, R4, R5, R9, R10, R11, R13;

[0024] One end of the pull-up resistor R2 is connected to the power supply, and the other end is connected to the non-inverting input terminal of the differential operational amplifier A1; one end of the pull-up resistor R3 is connected to the non-inverting input terminal of the differential operational amplifier A1, and the other end is grounded; one end of the pull-up resistor R1 is connected to the inverting input terminal of the differential operational amplifier A1, one end of the strain gauge Rb, and one end of the strain gauge Rd, and the other end is grounded;

[0025] One end of the resistor R6 is connected to the power supply, and the other end is connected to the non-inverting input terminal of the differential operational amplifier A2; one end of the resistor R7 is connected to the power supply, and the other end is grounded; one end of the resistor R4 is connected to the output terminal of the differential operational amplifier A1, and the other end is connected to the inverting input terminal of the differential operational amplifier A2; one end of the pull-up resistor R8 is connected to the output terminal of the differential operational amplifier A2, and the other end is connected to the pull-up resistor R1; one end of the resistor R5 is connected to the resistor R4, and the other end is connected to the resistor R8;

[0026] One end of the strain gauge Ra is connected to the output terminal of the differential operational amplifier A1, and the other end is connected to the strain gauge Rb and the resistor R13; one end of the strain gauge Rc is connected to the output terminal of the differential operational amplifier A1, and the other end is connected to the strain gauge Rd and the resistor R9; the non-inverting input terminal of the differential operational amplifier A3 is connected to the resistor R9, the inverting input terminal is connected to the resistor R13, one end of the resistor R10 is connected to the resistor R13, and the other end is connected to the output terminal of the differential operational amplifier A3.

[0027] The present invention has at least the following beneficial effects:

[0028] The present invention provides a sensor for casing make-up measurement that can meet the application scenarios of special working conditions and has certain economic effects. In this solution, a PCB slot, a radio frequency antenna slot, and a battery hole form an embedded measurement system channel. That is, there are two sets of identical embedded measurement system channels in this solution, which can simultaneously monitor the number of turns of thread rotation and the torque generated during thread mating in the thread connection process of casing drilling equipment, and more effectively ensure the quality of thread connection between equipment. And the accuracy of the current casing make-up turns and thread connection torque measurement can be determined by the difference in the measurement results of the two channels, and the switching between channels can be completed through program instructions, further improving the battery life of the equipment. And it also has a wireless transceiver function to realize the long-distance wireless transmission of data and instructions, which to a certain extent protects the personal safety of operators. And the temperature compensation of the strain gauge signal is realized through the hardware circuit, further improving the accuracy of the torque acquisition signal, which is of great significance in the application of collecting the make-up turns and thread tightening torque between oil drilling casings.

[0029] A sensor for casing make-up measurement proposed by the present invention can determine the accuracy of the current thread make-up turns and thread connection torque measurement by judging the difference between the two-channel measurement results, and can complete the functions of wake-up, sleep and switching between channels through program instructions, further improving the battery life of the device. Moreover, a sensor for casing make-up measurement provided by the present invention has completed the design of a Wheatstone bridge temperature compensation circuit according to the sensitivity of the negative temperature coefficient and the resistance change of the positive temperature coefficient of the strain gauge. Through the feedback mechanism of the compensation circuit, it can effectively compensate for the decrease in the output voltage of the Wheatstone bridge of the strain gauge caused by temperature.

[0030] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a schematic mechanical structure diagram of a sensor for casing make-up measurement of the present invention;

[0032] Figure 2 is a schematic system structure block diagram of a sensor for casing make-up measurement of the present invention;

[0033] Figure 3 is a schematic diagram of a Wheatstone full bridge circuit;

[0034] Figure 4 is the pasting position of a single Wheatstone full bridge circuit strain gauge on the strain axis;

[0035] Figure 5 is a schematic diagram of the principle of a Wheatstone bridge temperature compensation circuit;

[0036] Figure 6 is a top view of a sensor for casing make-up measurement of the present invention;

[0037] Figure 7 is a top sectional view of the explosion-proof housing of the present invention;

[0038] Figure 8 is a bottom view of the flange of a sensor for casing make-up measurement of the present invention;

[0039] Figure 9 is a side view of the flange of a sensor for casing make-up measurement of the present invention;

[0040] Figure 10 is a structural diagram of the strain axis of the present invention;

[0041] Figure 11 is a left half-sectional view of a sensor for casing make-up measurement of the present invention;

[0042] Figure 12 is a bottom view of the explosion-proof housing of the present invention.

[0043] In the figure: 1, strain axis; 2, explosion-proof housing; 3, top cover; 300, circular groove; 4, antenna cover; 5, battery cover; 6, rope buckle ring; 7, split pin; 8, gasket; 9, buckle; 10, battery box cover; 11, pull ring; 12, battery box; 13, bottom film of battery box; 14, lower bottom film of battery box; 15, small threaded cover; 16, antenna bracket; 17, antenna bracket plate; 18, antenna cap; 19, connecting bolt; 20, flange; 200, threaded groove; 201, fixing hole; 202, first positioning groove; 203, positioning hole; 204, second positioning groove; 21, positioning pin; 22, fastening screw; 23, large threaded cover; 24, PCB groove; 25, RF antenna groove; 26, battery hole; a, groove. Specific embodiments

[0044] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.

[0045] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying 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 construed as a limitation of the present invention.

[0046] Combined with Figures 1-12 to illustrate this embodiment,

[0047] This embodiment is a sensor for casing makeup measurement, including a strain axis 1. The body of the strain axis 1 is sleeved with an explosion-proof housing 2. Both ends of the strain axis 1 extending out of the explosion-proof housing 2 have connecting threads. A power module, a signal acquisition module, a wireless transceiver module, and a control module are arranged in the explosion-proof housing 2;

[0048] There is a circular annular space between the strain axis 1 and the explosion-proof housing 2. Strain gauges forming a Wheatstone bridge are attached to the body of the strain axis 1 and are located in this annular space. There are small holes facing the annular space in the PCB groove. The microcontroller in the PCB groove is connected to the strain gauge signal line through these small holes.

[0049] Among them, the signal acquisition module includes a Wheatstone bridge temperature compensation circuit for strain signal acquisition and temperature compensation.

[0050] In this embodiment, the power supply module includes a lithium battery, a voltage conversion module, and a battery management chip. The voltage conversion module is used to convert the voltage output by the lithium battery. The lithium battery is composed of two 3.6V batteries, which jointly output a power supply voltage of 7.2V. The voltage conversion module can respectively implement the voltage conversion of the power supply voltage from 7.2V to 3.3V and from 7.2V to 5V, so as to supply power to each module in the system.

[0051] During use, the voltage / current state of the power battery can be monitored in real time through the battery management chip. The microcontroller can directly access the data register in the battery management chip through the I2C bus to obtain the current battery power and discharge state.

[0052] In this embodiment, the wireless transceiver module uses Lora wireless spread spectrum communication technology for data transmission, and the RF antenna adopts an impedance design. By using high-frequency inductance and high-frequency capacitance elements, an LC oscillation circuit is obtained, so that the signal power at the source end can be transmitted to the load end to the maximum extent. The built-in RF antenna is fixed by the bracket inside the RF antenna slot 13 of the explosion-proof shell 2. The data sorted and packaged by the single-chip microcomputer is sent to the upper computer user terminal through Lora wireless spread spectrum communication technology, and at the same time, the register addressing instruction, the historical data reading and clearing instruction in the Flash memory, the entry and wake-up instruction of the low-power mode, etc. sent by the upper computer end are received. Among them, the Lora wireless spread spectrum communication technology has a longer transmission distance and encryption settings, making the collected data have higher reliability and security during the wireless signal transmission process.

[0053] The present invention proposes a sensor for casing make-up measurement that can meet the application scenarios of special working conditions and has certain economic effects. In this solution, a PCB slot 12, a RF antenna slot 13, and a battery hole 14 form an embedded measurement system channel. That is, there are two sets of the same embedded measurement system channels in this solution, which can simultaneously monitor the number of turns of the thread rotation and the torque generated during the thread mating in the thread connection process of the casing drilling equipment, and more effectively ensure the quality of the thread connection between equipment. And the accuracy of the current make-up turns of the thread and the measurement of the thread connection torque can be determined by the difference between the measurement results of the two channels, and the switching between channels can be completed through program instructions, further improving the battery life of the equipment. And it also has a wireless transceiver function to realize the long-distance wireless transmission of data and instructions, which to a certain extent protects the personal safety of the operators. And the temperature compensation of the strain gauge signal is realized through the hardware circuit, further improving the accuracy of the torque acquisition signal, which is of great significance in the application of collecting the make-up turns and the thread tightening torque between oil drilling casings.

[0054] A sensor for casing make-up measurement proposed by the present invention can determine the accuracy of the current thread make-up turns and the measurement of the thread connection torque through the difference in the two-channel measurement results, and can complete the functions of wake-up, sleep and switching between channels through program instructions, further improving the battery life of the device. Moreover, a sensor for casing make-up measurement provided by the present invention completes the design of the temperature compensation circuit of the Wheatstone bridge according to the sensitivity of the negative temperature coefficient and the resistance change of the positive temperature coefficient of the strain gauge. Through the feedback mechanism of the compensation circuit, the reduction of the output voltage of the Wheatstone bridge of the strain gauge caused by temperature can be effectively compensated. In addition, a sensor for casing make-up measurement provided by the present invention has a wireless transceiver function to realize the long-distance wireless transmission of data and instructions, which to a certain extent protects the personal safety of operators.

[0055] Further, the strain gauges of the Wheatstone bridge are uniformly distributed on the 360° body of the strain axis 1 at an angle of 45° with the central axis of the strain axis 1, and are alternately arranged with the axis baseline of the strain axis 1 at angles of 45° and 135°.

[0056] In this embodiment, 8 strain gauges are pasted on the circular ring surface at the assembly place of the strain axis 1 and the explosion-proof housing 2. The 8 strain gauges are uniformly distributed on the 360° circular ring surface at an angle of 45°, and are alternately arranged with the axis baseline of the strain axis 1 at angles of 45° and 135°, jointly constituting two sets of Wheatstone full-bridge circuits.

[0057] Further, the body of the strain axis 1 is provided with an annular groove surface, which encloses the annular space with the inner wall of the explosion-proof housing 2;

[0058] Both sides of the explosion-proof housing 2 are axially limited through the shoulders on the strain axis 1 and the flange 20.

[0059] In this embodiment, the material of the strain axis 1 is selected as 40CrNiMo or 40CrNi2MoA alloy with high strength and good toughness. Tapered external threads and tapered internal threads are designed at both ends, which can realize the thread assembly with external casing drilling equipment, effectively transmit the torque applied by the drilling equipment and generate deformation. The material of the explosion-proof housing 2 is selected as non-magnetic alloy P550 to avoid the shielding and absorption of the wireless electromagnetic wave signal transmission in the antenna groove by magnetic materials. The explosion-proof housing 2 is installed on the shoulder of the strain axis 1, and a flange 20 is arranged below. The explosion-proof housing 2 is fixed up and down through the shoulder of the strain axis 1 and the flange 20, thereby realizing the axial limit of the explosion-proof housing 2 on the strain axis 1.

[0060] Further, two sets of embedded measurement system channels are symmetrically arranged on the explosion-proof housing 2, and each set of channels includes a connected PCB slot 24, a radio frequency antenna slot 25 and a battery hole 26;

[0061] The PCB slot 24 is communicated with the battery hole 26 through a through hole to lead out battery wires, and is communicated with the RF antenna slot 25 through another through hole for signal wires;

[0062] A top cover 3 and an antenna cover 4 are respectively arranged on the PCB slot 24 and the RF antenna slot 25;

[0063] Wherein, a battery is placed in the battery hole 26 to form the power supply module, a wireless antenna is placed in the RF antenna slot 25 to form the wireless transceiver module, and a microcontroller is placed in the PCB slot 24 to form the control module;

[0064] A large threaded cover 23 is arranged on the explosion-proof shell 2 for sealing the guide hole between the PCB slot 24 and the RF antenna slot 25.

[0065] In this embodiment, an antenna support 16 is arranged in the RF antenna slot 25. An antenna support plate 17 is arranged at the shoulder of the antenna support 16. An antenna cap 18 is arranged on the antenna support plate 17. A small threaded cover 15 is arranged on the explosion-proof shell 2 for sealing the auxiliary guide hole in the antenna slot area.

[0066] The explosion-proof shell 2 is a centrosymmetric structure. Inside the explosion-proof shell 2, two PCB slots 12, two RF antenna slots 13, and two battery holes 14 are sequentially arranged in a surrounding and symmetric manner. The PCB slot 12, the RF antenna slot 13, and the battery hole 14 are respectively used for installing a hardware circuit board, a wireless transceiver module with an RF antenna, and a power battery. The PCB slot 12, the RF antenna slot 13, and the battery hole 14 are electrically connected to each other through power line through holes inside the explosion-proof shell 2 to realize the connection of signal lines and power lines inside the embedded system. In this solution, one PCB slot 12, one RF antenna slot 13, and one battery hole 14 form an embedded measurement system channel. That is, this solution includes two sets of identical embedded measurement system channels in total, which can simultaneously monitor the number of turns of thread rotation and the torque generated during thread mating in the process of thread connection of the casing drilling equipment, and more effectively ensure the quality of thread connection between devices. And the accuracy of the number of thread fastening turns and the measurement of thread connection torque on the current thread can be determined by the difference in the measurement results of the two channels, and the switching between channels can be completed through program instructions, further improving the battery life of the device.

[0067] In this embodiment, the microcontroller consists of a single-chip microcomputer, a crystal oscillator circuit, a reset circuit, and a program download interface; the single-chip microcomputer uses an STM32G474 chip, which is used to sort, store, and package data; in this embodiment, the single-chip microcomputer also provides a choice between a working mode and a low-power shutdown mode. The crystal oscillator circuit includes a 48MHz external passive crystal oscillator and a 16MHz internal passive crystal oscillator, and is equipped with matching capacitors and resistors to maintain the normal operation of the single-chip microcomputer. The reset circuit includes a window watchdog, which is used to verify the operation of the entire embedded system program and perform a power-down reset of the single-chip microcomputer. By enabling the window watchdog through the GPIO port of the single-chip microcomputer, the functions of verifying the operation of the entire embedded system program and performing a power-down reset of the single-chip microcomputer can be achieved. The program download interface is an external 4×1 program download interface driven by ST-Link, and multiple download interfaces are respectively connected to the SWCLK, SWDIO, VCC, and GND pins of the single-chip microcomputer.

[0068] Further, a battery box 12 and a battery box cover 10 with a pull ring 11 are provided in the battery hole 26. A battery box upper bottom plate 13 and a battery box lower bottom plate 14 are provided at the bottom of the battery box 12; the pull ring 11 is hinged in a groove at the end of the battery box cover 10 for easy unfolding and folding.

[0069] Among them, a through hole is provided at the bottom of the battery box 12, and the battery box upper bottom plate 13 and the battery box lower bottom plate 14 are sequentially assembled at both ends of the through hole at the bottom of the battery box 12.

[0070] A battery cover 5 is provided at the opening of the battery hole 26. A buckle 9 is inserted through the protruding section of the battery cover 5 outward. The folding surface of the buckle 9 abuts against the axial end surface of the explosion-proof housing 2 to prevent the battery box 12 from rotating. A through hole is horizontally provided on the protruding section of the battery cover 5 outward. An open pin 7 is inserted into the through hole. A gasket 8 is sleeved on the battery box 12, and the gasket 8 is located inside the open pin 7. A rope buckle ring 6 is provided on the outer side of the battery cover 5.

[0071] In this embodiment, a battery box 12 and a battery box cover 10 with a pull ring 11 are provided in the battery hole 26. The battery box cover 10 and the battery box 12 are assembled by threading. The material of the battery box 12 is polytetrafluoroethylene with good insulation, and the material of the battery box cover 10 is CuNi10Fe with good conductivity. A stepped through hole with a small middle hole diameter and large hole diameters on both sides is opened at the bottom of the battery box 12. The upper bottom plate 13 of the battery box and the lower bottom plate 14 of the battery box are sequentially assembled at both ends of the through hole at the bottom of the battery box 12. Threaded through holes are opened at the centers of the upper bottom plate 13 of the battery box and the lower bottom plate 14 of the battery box. By inserting a screw into this threaded through hole, the installation and fixation of the upper bottom plate 13 of the battery box, the lower bottom plate 14 of the battery box and the battery box 14 can be realized. The pull ring 11 is installed in the groove of the battery box cover 10. When replacing the battery, the pull ring 11 can be pulled out by hand, and the disassembly of the battery box cover 10 and the battery box 12 can be realized by twisting the pull ring 11. The battery cover 5 is threadedly and adaptively connected to the explosion-proof housing 2 to realize the encapsulation of the battery area and the return of the battery negative electrode. The material of the battery cover 5 is selected as CuNi10Fe with good conductivity. A buckle 9 is passed through the protruding section of the battery box 12. The folded surface of the buckle 9 abuts against the axial end face of the explosion-proof housing 2 to prevent the battery box 12 from rotating. The buckle 9 and the battery cover 5 are coplanar. The tight fit between the two is realized through a gasket 8. The split pin 7 is inserted into the through hole horizontally arranged on the protruding section of the battery cover 5 to apply a pre-tightening force to the gasket 8, thereby playing a clamping role and ensuring the tight fit between the buckle 9 and the battery box 5. The folded surface of the buckle 9 is self-locked with the end face of the explosion-proof housing 2 to prevent the rotation of the battery box 5 and ensure the threaded assembly with the explosion-proof housing 2. A threaded hole is opened on the protruding section of the battery cover 5. A screw is inserted into the rope buckle ring 6 and the threaded hole to realize the assembly connection between the rope buckle ring 6 and the battery cover 5.

[0072] Further, a flange 20 is sleeved on the strain shaft 1. A plurality of first positioning grooves 202 are arranged on one side of the flange 20 facing the explosion-proof housing 2. Second positioning grooves 204 corresponding to the first positioning grooves 202 are arranged on the explosion-proof housing 2. A positioning pin 21 is movably arranged in the space formed by the first positioning grooves 202 and the second positioning grooves 204. A positioning hole 203 extending outward is arranged on the groove wall of the first positioning groove 202. A fastening screw 22 for pressing the positioning pin 21 is fitted in the positioning hole 203. A circular groove 300 corresponding to the radial end of the positioning pin 21 is arranged on the strain shaft 1;

[0073] Fixing holes 201 are opened on both sides of the first positioning groove 202. Connecting bolts 19 for connecting with the explosion-proof housing 2 are fitted in the fixing holes 201.

[0074] The flange 20 is symmetrically arranged about the center, and there are 8 fixing holes 201 at the end. The connecting bolt 19 passes through the fixing holes 201 on the flange 20 and is connected to 8 threaded grooves 200 correspondingly opened on the explosion-proof shell 2 to realize the radial fixation of the flange 20. The positioning pin 21 is movably installed in the space formed by the first positioning groove 202 and the second positioning groove 204, and is threadedly assembled with the flange 20 through the fastening screw 22. A pre-tightening force is applied to the positioning pin 21 to make the positioning pin 21 insert into the circular groove 300 opened on the strain shaft 1, realizing the fixation of the explosion-proof shell 2 on the strain shaft 1.

[0075] Further, two grooves a are symmetrically arranged on the outer periphery of the explosion-proof shell 2. On one side wall of the groove a, there are battery holes 26 extending in the same direction and the first through hole for communicating with the PCB groove 24;

[0076] On the other side wall of the groove a, there is a processing hole for penetrating the RF antenna groove 25. The far side section of this processing hole forms the second through hole for communicating with the PCB groove 24, and a large thread cover 23 is provided at the mouth end of this processing hole.

[0077] Through the arrangement of the groove a, it is convenient to perform processing in the chord direction of the explosion-proof shell 2. When processing, it gives way through the groove a. For example, when drilling, when turning the battery hole, the drilling tool does not interfere with the explosion-proof shell 2. At the same time, it is convenient to process the first through hole, reducing the process holes processed on the outer wall of the PCB groove 24 on the explosion-proof shell 2, which can improve the strength and sealing performance of the explosion-proof shell 2 at this place, reduce the need for sealing process holes. The setting principle of the processing hole is the same, which can facilitate processing, improve the strength and sealing performance of the PBC groove 24, and at the same time prevent the parts (such as split pins and covers) located in the side wall of the groove a from interfering with the outside, thereby improving the service life of the parts during operation.

[0078] Further, the signal acquisition module further includes a three-axis gyroscope. The three-axis gyroscope uses an ADXRS453 angular velocity sensor and is packaged in SOIC_CAV, and is used to collect the number of thread make-up turns.

[0079] During the threaded assembly between casing drilling equipment, the three-axis gyroscope is used to collect the make-up acceleration of the equipment on the thread in real time, and the Kalman filtering algorithm and attitude fusion algorithm are used to convert the acceleration into the number of rotating turns, thereby realizing the collection of the number of thread make-up turns.

[0080] In this embodiment, an ADXRS453 angular velocity sensor is selected as the gyroscope. The sensor adopts a differential four-sensor design, which can detect an angular velocity of up to ±300° / s. At the same time, it effectively avoids the influence of linear acceleration, enabling it to provide high-precision sensing signals in harsh environments with shock and vibration. The ADXRS453 angular velocity sensor is packaged using SOIC_CAV, so that only the angular velocity value of the z-axis (yaw angle) can be collected, avoiding interference from the acquisition signals of the x-axis (pitch angle) and the y-axis (roll angle).

[0081] Further, the signal acquisition module further includes an A / D conversion circuit and a temperature sensor, which are respectively used for analog-to-digital conversion of the Wheatstone bridge signal and real-time temperature measurement and alarm of the working area.

[0082] The A / D conversion circuit includes a 24-bit AD conversion module, whose function is to convert the amplified voltage analog signal into a digital signal and transmit the converted data to the single-chip microcomputer through the SPI bus.

[0083] The DS18B9 temperature sensor is used as the temperature sensor to collect the temperature signal of the working area in real time. The temperature sensor transmits the collected temperature data to the single-chip microcomputer through the one-wire communication protocol. Through the setting of the temperature sensor, alarms can also be given when the circuit board is short-circuited, or the ambient or CPU temperature is too high.

[0084] Further, the Wheatstone bridge temperature compensation circuit includes: differential operational amplifiers A1, A2, A3, pull-up resistors R1, R2, R3, R8, strain gauges Ra, Rb, Rc, Rd, resistors R6, R7, R4, R5, R9, R10, R11, R13;

[0085] One end of the pull-up resistor R2 is connected to the power supply, and the other end is connected to the non-inverting input terminal of the differential operational amplifier A1; one end of the pull-up resistor R3 is connected to the non-inverting input terminal of the differential operational amplifier A1, and the other end is grounded; one end of the pull-up resistor R1 is connected to the inverting input terminal of the differential operational amplifier A1, one end of the strain gauge Rb, and one end of the strain gauge Rd, and the other end is grounded;

[0086] One end of the resistor R6 is connected to the power supply, and the other end is connected to the non-inverting input terminal of the differential operational amplifier A2; one end of the resistor R7 is connected to the power supply, and the other end is grounded; one end of the resistor R4 is connected to the output terminal of the differential operational amplifier A1, and the other end is connected to the inverting input terminal of the differential operational amplifier A2; one end of the pull-up resistor R8 is connected to the output terminal of the differential operational amplifier A2, and the other end is connected to the pull-up resistor R1; one end of the resistor R5 is connected to the resistor R4, and the other end is connected to the resistor R8;

[0087] One end of the strain gauge Ra is connected to the output end of the differential operational amplifier A1, and the other end is connected to the strain gauge Rb and the resistor R13; one end of the strain gauge Rc is connected to the output end of the differential operational amplifier A1, and the other end is connected to the strain gauge Rd and the resistor R9; the non-inverting input end of the differential operational amplifier A3 is connected to the resistor R9, the inverting input end is connected to the resistor R13, one end of the resistor R10 is connected to the resistor R13, and the other end is connected to the output end of the differential operational amplifier A3.

[0088] A sensor for casing make-up measurement proposed by the present invention internally adopts a Wheatstone bridge temperature compensation circuit composed of three differential operational amplifiers and matching resistors. Through the feedback mechanism of the compensation circuit, it can effectively compensate the strain gauge acquisition error caused by temperature and improve the acquisition accuracy of the sensor for the make-up torque of the thread.

[0089] In this embodiment, 8 strain gauges are evenly pasted at an interval of 45° angles in the annular surface of the strain axis 1 through polyacrylic resin, and are alternately arranged at angles of 45° and 135° with the axis baseline of the strain axis 1, jointly constituting two Wheatstone full-bridge circuits. When the strain axis 1 bears torque, shear strain will occur along the 45° and 135° spiral directions of the axis, causing the strain gauges along the same pasting direction to undergo the same small strain, resulting in a change in resistivity.

[0090] As Figure 4 shown, the strain gauge can be regarded as a force-sensitive resistor with an initial resistance of R. For a single Wheatstone full-bridge circuit composed of a total of 4 strain gauges Ra, Rb, Rc, and Rd, by providing the working voltage Ui to this bridge and collecting the differential signal, i.e., the potential difference U0, between the bridge arms, the voltage output signal corresponding to the pure shear deformation under torque can be obtained.

[0091] As Figure 5 shown, the pasting method of the 4 strain gauges on the torque axis should satisfy the pasting angles as shown in the figure. The strain gauge Ra and the strain gauge Rb on one unilateral bridge arm form a parallel circuit with the strain gauge Rc and the strain gauge Rd on the other unilateral bridge arm, and it is ensured that the pasting directions of the strain gauge Ra and the strain gauge Rd are the main directions of the torque normal stress.

[0092] For the Wheatstone full-bridge circuit, when torque is applied and the resistance of the strain gauge changes, the output voltage Uo can be obtained by taking the difference in potential between the bridge arm points. Ignoring the second-order small quantity, there is:

[0093]

[0094] An equal-arm Wheatstone bridge composed of the same strain gauges has Ra = Rb = Rc = Rd = R, and the absolute values of the resistance changes are equal under the same strain. There is:

[0095]

[0096] Among them, U o is the full-bridge differential signal collected, U i is the power input voltage, k is the sensitivity factor of the strain gauge, and ε is the strain of the strain gauge. For the strain axis 1 of the through hole, its polar moment of inertia I p should be:

[0097]

[0098] Among them, R L is the outer diameter of the strain axis 1, and r L is the diameter of the central hole of the strain axis 1. Then the magnitude of the shear stress τ generated under the applied torque T is:

[0099]

[0100] Among them, Ip is the polar moment of inertia of the cross-section of the strain axis 1. Since the strain axis 1 is in pure shear strain, the strain magnitude of the strain axis 1 in the principal stress direction is:

[0101]

[0102] Among them, ε is the strain under the action of the torque, τ is the magnitude of the shear stress on the outermost surface under the action of the torque, v is the Poisson's ratio, and Ep is the Young's modulus of the strain axis 1. Therefore, the relationship between the strain ε and the torque T is obtained as:

[0103]

[0104] Among them, G is the shear modulus of the strain axis 1, which is related to the Poisson's ratio and the Young's modulus. Then the final relationship between the torque T and the differential voltage signal U0 is:

[0105]

[0106] From the positive temperature characteristic of the strain gauge resistance and the negative temperature characteristic of the sensitivity, it can be seen that the total resistance of the bridge circuit increases with the increase of temperature, and the sensitivity decreases with the increase of temperature. Therefore, it can be known from equation (2) that the differential output voltage U o decreases, resulting in the measured value of the sensor being smaller than the actual value, leading to measurement errors. Therefore, temperature compensation must be carried out on it.

[0107] Such as Figure 6As shown, the Wheatstone bridge temperature compensation circuit is composed of a constant current source circuit, a constant current source temperature compensation circuit, a differential amplifier circuit at the bridge output end, and a strain acquisition circuit. The constant current source circuit is composed of a differential operational amplifier A1 and surrounding matching resistors. The constant current source temperature compensation circuit is composed of a differential operational amplifier A2 and surrounding matching resistors. The differential amplifier circuit at the bridge output end is composed of a differential operational amplifier A3 and surrounding matching resistors. The differential operational amplifier A1, the bridge resistors R1, R2, R3, and the Wheatstone full bridge circuit constitute a strain acquisition circuit with a constant current source excitation. Since the total resistance of the bridge circuit increases, the output voltage Vs of the constant current source composed of the differential operational amplifier A1 increases. Then, the reverse output voltage Vt of the differential operational amplifier A2 decreases. Then, the current through the feedback pull-up resistor R8 decreases, thereby feeding back to the Wheatstone bridge to increase the bridge current, making the differential output voltage U o increase, realizing the temperature compensation of the output voltage U o of the entire Wheatstone bridge. After passing through the differential operational amplifier A3, the measured voltage after temperature compensation can be read.

[0108] The differential operational amplifier with A2 as the inverting terminal, according to the output voltage of the basic differential operational amplifier circuit:

[0109]

[0110] When the amplifier gain resistance ratio is obtained:

[0111] V t = i(E - V s ) (9)

[0112] It can be known from the constant current source composed of the differential operational amplifier A1 and surrounding matching resistors:

[0113]

[0114] Among them, R is the total resistance of the Wheatstone bridge. Substituting equation (9) into equation (10) gives:

[0115]

[0116] Further deduced:

[0117]

[0118] When strain occurs and a voltage difference is generated at the bridge arm end, combining equations (2) and (12) shows that:

[0119]

[0120] In Equation (13), since the Wheatstone bridge resistance R has a positive temperature coefficient and the sensing sensitivity ΔR has a negative temperature coefficient, the denominator R8i - R has a negative temperature coefficient. Compared with Expression (2), by reasonably designing the temperature compensation circuit and selecting the differential operational amplifier gain resistor ratio i and the feedback pull-up resistor R8, the positive / negative temperature coefficients of the resistance and sensitivity of the Wheatstone bridge caused by temperature can be offset for the output voltage U o to achieve the purpose of temperature compensation.

[0121] It should also be noted that the term "including", "comprising" or any other variant thereof is intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or elements inherent to such a process, method, commodity or device. Without further limitation, an element defined by the statement "including one..." does not exclude the existence of another identical element in the process, method, commodity or device including the element. The words such as first and second are used to represent names and do not represent any specific order. The present invention and its implementation manners are schematically described above. The description is not restrictive. Without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. What is shown in the drawings is only one of the implementation manners of the present invention. The actual structure is not limited thereto. Any reference numeral in the claims should not limit the claimed claim. Therefore, if those of ordinary skill in the art are inspired by it and design similar structural manners and embodiments to the technical solution without creative efforts without departing from the purpose of this creation, they should all fall within the protection scope of this application.

Claims

1. A sensor for measuring casing make-up, characterized in that: The invention comprises a strain shaft (1), wherein the strain shaft (1) is sleeved with an explosion-proof housing (2), and the two ends of the strain shaft (1) extending out of the explosion-proof housing (2) are provided with connecting threads, and the explosion-proof housing (2) is provided with a power supply module, a signal acquisition module, a wireless transceiver module, and a control module; There is a circular annular space between the strain shaft (1) and the explosion-proof housing (2), and a strain gauge constituting a Wheatstone bridge is attached to the shaft of the strain shaft (1) and is located in the annular space. Wherein, the signal acquisition module includes a Wheatstone bridge temperature compensation circuit, which is used for strain signal acquisition and temperature compensation.

2. A sensor for casing make-up measurement according to claim 1, characterized in that: The strain gauges of the Wheatstone bridge are evenly distributed on the 360° axis of the strain axis (1) at an angle of 45° to the central axis of the strain axis (1), and are alternately arranged at angles of 45° and 135° to the axis base of the strain axis (1).

3. A sensor for casing make-up measurement according to claim 1, characterized in that: The strain shaft (1) is provided with an annular groove surface, which, together with the inner wall of the explosion-proof housing (2), forms the annular space; The two sides of the explosion-proof housing (2) are axially limited by the cooperation of the shaft shoulder on the strain shaft (1) and the flange (20).

4. A sensor for casing make-up measurement according to claim 3, characterized in that: The explosion-proof housing (2) is symmetrically provided with two groups of embedded measurement system channels, each group of channels comprising a connected PCB slot (24), a radio frequency antenna slot (25) and a battery hole (26); The PCB slot (24) is connected to the battery hole (26) through a through hole and leads out a battery wire, and is connected to the radio frequency antenna slot (25) through another through hole to connect a signal line; The PCB slot (24) and the radio frequency antenna slot (25) are respectively provided with a top cover (3) and an antenna cover (4). The battery is placed in the battery hole (26) to form the power module, the wireless antenna is placed in the radio frequency antenna slot (25) to form the wireless transceiver module, and the microcontroller is placed in the PCB slot (24) to form the control module.

5. A sensor for casing make-up measurement according to claim 4, characterized in that: A battery box (12) and a battery box cover (10) with a pull ring (11) are arranged in the battery hole (26); a battery box upper bottom sheet (13) and a battery box lower bottom sheet (14) are arranged at the bottom of the battery box (12); the pull ring (11) is hinged in a groove at the end of the battery box cover (10) to facilitate unfolding and folding. The bottom of the battery box (12) is provided with a through hole, and the upper bottom plate (13) and the lower bottom plate (14) are sequentially assembled at two ends of the through hole at the bottom of the battery box (12); The battery hole (26) is provided with a battery cover (5) at its opening, a buckle (9) is inserted through the outwardly protruding section of the battery cover (5), the folded surface of the buckle (9) abuts against the axial end surface of the explosion-proof housing (2) to prevent the battery box (12) from rotating, a through hole is transversely provided at the outwardly protruding section of the battery cover (5), a cotter pin (7) is inserted into the through hole, a gasket (8) is sleeved on the battery box (12), the gasket (8) is located on the inner side of the cotter pin (7), and a rope buckle ring (6) is provided on the outward side of the battery cover (5).

6. A sensor for casing make-up measurement according to claim 1, characterized in that: The strain shaft (1) is sleeved with a flange (20), and a plurality of first positioning grooves (202) are arranged on the side of the flange (20) facing the explosion-proof housing (2), and a second positioning groove (204) corresponding to the first positioning groove (202) is arranged on the explosion-proof housing (2), and a positioning pin (21) is movably arranged in a space formed by the first positioning groove (202) and the second positioning groove (204), and a positioning hole (203) extending outward is arranged on the groove wall of the first positioning groove (202), and a fastening screw (22) for tightening the positioning pin (21) is fitted in the positioning hole (203), and a circular groove (300) corresponding to the radial end of the positioning pin (21) is arranged on the strain shaft (1); Fixing holes (201) are provided on both sides of the first positioning groove (202), and connecting bolts (19) for connecting with the explosion-proof housing (2) are arranged in the fixing holes (201).

7. A sensor for casing make-up measurement according to claim 1, characterized in that: The explosion-proof housing (2) is symmetrically provided with two grooves (a) on its outer periphery, and a battery hole (26) extending in the same direction and a first through hole for connecting to the PCB slot (24) are provided on one side wall of the groove (a); The other side wall of the groove (a) is provided with a processing hole for penetrating the radio frequency antenna slot (25), and the distal section of the processing hole forms a second through hole for connecting to the PCB slot (24), and the mouth end of the processing hole is provided with a large threaded cover (23).

8. A sensor for casing make-up measurement according to claim 1, characterized in that: The signal acquisition module integrates a three-axis gyroscope for collecting the number of thread turns; The signal acquisition module also includes an A / D conversion circuit and a temperature sensor, which are respectively used for analog-to-digital conversion of the Wheatstone bridge signal and real-time temperature measurement and alarm in the working area.

9. A sensor for casing make-up measurement according to claim 1, characterized in that: The Wheatstone bridge temperature compensation circuit includes: differential operational amplifiers A1, A2, A3, pull-up resistors R1, R2, R3, R8, strain gauges Ra, Rb, Rc, Rd, resistors R6, R7, R4, R5, R9, R10, R11, R13; One end of the pull-up resistor R2 is connected to the power supply, and the other end is connected to the non-inverting input terminal of the differential operational amplifier A1; one end of the pull-up resistor R3 is connected to the non-inverting input terminal of the differential operational amplifier A1, and the other end is grounded; one end of the pull-up resistor R1 is connected to the inverting input terminal of the differential operational amplifier A1, one end of the strain gauge Rb, and one end of the strain gauge Rd, and the other end is grounded; One end of the resistor R6 is connected to the power supply, and the other end is connected to the non-inverting input end of the differential operational amplifier A2; one end of the resistor R7 is connected to the power supply, and the other end is grounded; one end of the resistor R4 is connected to the output end of the differential operational amplifier A1, and the other end is connected to the inverting input end of the differential operational amplifier A2; one end of the pull-up resistor R8 is connected to the output end of the differential operational amplifier A2, and the other end is connected to the pull-up resistor R1; one end of the resistor R5 is connected to the resistor R4, and the other end is connected to the resistor R8; One end of the strain gauge Ra is connected to the output end of the differential operational amplifier A1, and the other end is connected to the strain gauge Rb and the resistor R13; one end of the strain gauge Rc is connected to the output end of the differential operational amplifier A1, and the other end is connected to the strain gauge Rd and the resistor R9; the non-inverting input end of the differential operational amplifier A3 is connected to the resistor R9, and the inverting input end is connected to the resistor R13; one end of the resistor R10 is connected to the resistor R13, and the other end is connected to the output end of the differential operational amplifier A3.

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