A tubing corrosion detection device and method with a non-uniform speed plunger integrated magnetic flux sensor

Abstract

This application relates to the field of tubing inspection technology, specifically disclosing a tubing corrosion detection device and method using a non-uniform motion plunger integrated with a magnetic flux sensor. The tubing corrosion detection device includes a plunger body, a magnetic flux detection module, a motion sensing module, a centering buffer module, and a data processing and transmission module. The magnetic flux detection module is distributed around the outer periphery of the plunger body. The magnetic flux detection module includes a magnetization unit and a magnetic flux sensor array. The magnetization unit is configured to generate a magnetic field to magnetize the tubing wall. The magnetic flux sensor array is configured to collect magnetic flux leakage signals at corrosion defects in the tubing. The data processing and transmission module has a built-in embedded processor configured to perform non-uniform signal compensation. Through the coordinated operation of its modules, this device can achieve online detection of tubing corrosion under non-uniform plunger motion of 3-5 m / s, without production shutdown, improving detection efficiency by 2-3 times.

Description

Technical Field

[0001] This application relates to the field of oil pipe inspection technology, specifically disclosing an oil pipe corrosion detection device and method using a non-uniform motion plunger integrated magnetic flux sensor. Background Technology

[0002] During the development of oil and gas fields, tubing, as a core component of the wellbore, is subject to long-term exposure to factors such as downhole corrosive media, pressure shocks, and temperature changes. This can easily lead to corrosion defects such as wall thinning, pitting, and cracks, which not only reduce the operating efficiency of the plunger drainage process but may also cause wellbore leaks, stuck pipes, and other safety accidents. Therefore, it is crucial to conduct regular corrosion inspections on tubing.

[0003] Magnetic flux leakage (MFL) detection is the mainstream technology for detecting corrosion in oil pipes. Its principle is to saturate the oil pipe wall with magnetization unit. When there is a corrosion defect in the pipe wall, the magnetic field will leak. The defect can be identified by collecting the leakage signal through the sensor. Current magnetic flux detection devices are mainly divided into fixed-installation type and low-speed traction type. The detection speed is usually less than 2m / s, and the low-speed traction type requires an external traction device, which cannot be combined with the plunger drainage process. Some detection devices that attempt to integrate with the plunger have the following core problems due to the lack of structural design and signal processing strategies for non-uniform motion: 1) In the plunger drainage process, the plunger moves at a non-uniform reciprocating speed of 3-5 m / s. If the current magnetic flux detection device is combined with the plunger, it will cause severe velocity distortion and baseline drift of the magnetic flux signal, making it difficult to extract the defect features of the tubing, resulting in a high rate of missed detection and false detection; 2) Under high-speed motion, the magnetic flux sensor is prone to collision with the inner wall of the tubing, and the large fluctuation of the detection spacing will further affect the signal accuracy; 3) The velocity signal and the magnetic flux signal are not synchronized, making it impossible to achieve accurate axial positioning of defects based on the plunger's motion trajectory.

[0004] In summary, there is currently no magnetic flux detection device or method for tubing corrosion that can adapt to the non-uniform motion conditions of the plunger at 3-5 m / s while taking into account detection accuracy, structural reliability, and positioning accuracy. This has become a key technical bottleneck restricting online corrosion detection of tubing in the plunger drainage process. Summary of the Invention

[0005] Given that there is currently no magnetic flux detection device or method for tubing corrosion that can adapt to the non-uniform motion of the plunger at 3-5 m / s while balancing detection accuracy, structural reliability, and positioning accuracy, this has become a key technical bottleneck restricting online tubing corrosion detection in the plunger drainage process. This application proposes the following technical solution to address this problem, enabling online, high-precision, and accurate positioning detection of tubing corrosion under non-uniform plunger motion at 3-5 m / s, while ensuring the reliability and stability of the device under harsh wellbore conditions.

[0006] In the first aspect, this application proposes an oil pipe corrosion detection device with an integrated magnetic flux sensor for a non-uniform motion plunger, and adopts the following technical solution.

[0007] A pipe corrosion detection device with an integrated magnetic flux sensor for a non-uniform motion plunger includes a plunger body, a magnetic flux detection module, a motion sensing module, a centering buffer module, and a data processing and transmission module.

[0008] The plunger body has a hollow structure.

[0009] The magnetic flux detection module is distributed around the outer periphery of the plunger body. The magnetic flux detection module includes a magnetization unit and a magnetic flux sensor array. The magnetization unit is configured to generate a magnetic field to magnetize the tubing wall. The magnetic flux sensor array is configured to collect magnetic flux leakage signals at corrosion defects in the tubing.

[0010] The motion sensing module is integrated into the plunger body and includes a speed measuring unit and a displacement measuring unit, which are used to collect the real-time motion speed and axial displacement of the plunger, and are synchronized with the clock of the magnetic flux detection module.

[0011] The centering buffer module is disposed on the outer wall of the plunger body and is used to adjust the detection distance between the magnetic flux sensor array and the inner wall of the oil pipe within the required range.

[0012] The data processing and transmission module has a built-in embedded processor, which is configured to perform non-uniform signal compensation.

[0013] By adopting the above technical solution, this device is equipped with a centering buffer module that abuts against the inner wall of the oil pipe. Under high-speed movement, the magnetic flux sensor will basically not collide with the inner wall of the oil pipe, resulting in small fluctuations in the detection spacing and improving signal accuracy. The real-time movement speed and axial displacement of the plunger are synchronized with the collected magnetic flux signal clock, enabling precise axial positioning of defects based on the plunger's movement trajectory. The data processing and transmission module has a built-in embedded processor configured to perform non-uniform speed signal compensation. This allows the device to achieve online detection of oil pipe corrosion under non-uniform plunger movement of 3-5 m / s through the coordinated work of various modules, without production shutdown, and improving detection efficiency by 2-3 times.

[0014] A preferred embodiment of the oil pipe corrosion detection device with an integrated magnetic flux sensor for a non-uniform motion plunger is that the magnetization unit includes an N-pole magnetic ring, an S-pole magnetic ring, and several magnetic strips. The magnetic strips are uniformly distributed along the outer circumference of the plunger body. The N-pole and S-pole magnetic rings are respectively sleeved on the outer wall of the plunger body and arranged axially opposite each other. The two ends of each magnetic strip are connected to the N-pole and S-pole magnetic rings respectively to form a closed magnetic circuit. The magnetic flux sensor array is disposed in the gap between adjacent magnetic strips.

[0015] By adopting the above technical solution, the oil pipe wall is saturated with magnetization through the closed magnetic circuit formed by the N-pole magnetic ring, S-pole magnetic ring and magnetic strip, ensuring that a detectable leakage magnetic field is generated at the defect. The sensor array is located in the gap of the magnetic strip, ensuring that the magnetic flux sensor is not blocked and can directly collect the leakage magnetic signal.

[0016] A preferred embodiment of the oil pipe corrosion detection device with integrated magnetic flux sensor for non-uniform motion plunger is that the magnetic flux sensor array is uniformly embedded in the groove of the outer wall of the plunger body, and the outer surface of the magnetic flux sensor array is flush with the outer wall of the plunger body.

[0017] By adopting the above technical solution, the sensor surface is flush with the outer wall of the plunger body, ensuring that the outer diameter of the device is minimized and avoiding the sensor protruding and colliding with the inner wall of the oil pipe. The distance between the plunger body and the inner wall of the oil pipe is generally very small. This setting retains an appropriate magnetic flux detection distance and improves detection accuracy.

[0018] A preferred embodiment of the oil pipe corrosion detection device with a non-uniform motion plunger integrated magnetic flux sensor is as follows: the oil pipe corrosion detection device with a non-uniform motion plunger integrated magnetic flux sensor includes two sets of the aforementioned straightening buffer modules, respectively disposed at the upper and lower parts of the plunger body; each set of the straightening buffer module includes several straightening wheels, several buffer springs, annular spring seats, several wheel axles, and several guide rods; the annular spring seats are embedded in an annular groove on the outer wall of the plunger body; the several straightening wheels are evenly distributed along the circumference of the plunger body; each wheel axle rotatably passes through the central hole of one of the straightening wheels. Each end of the axle is connected to one end of a buffer spring, and the other end of the buffer spring is fixed to the annular spring seat. Multiple guide holes are formed on the side wall of the plunger body. Multiple guide tubes are arranged inside the plunger body, with one end of each guide tube fixed to the periphery of the guide hole. A guide rod passes through the interior of the buffer spring. One end of the guide rod is fixed to one end of the axle, and the other end passes through the guide hole and slides appropriately within the guide tube. The centering wheel rolls in contact with the inner wall of the oil pipe, resulting in a distance of 5-8 mm between the magnetic flux detection module and the inner wall of the oil pipe.

[0019] By adopting the above technical solution, the upper and lower sets of straightening buffer modules protect the upper and lower ends of the plunger, preventing the plunger body from tilting excessively and causing the magnetic flux detection module to touch the inner wall of the oil pipe; the straightening wheel rolls in contact with the inner wall of the oil pipe, reducing frictional resistance; the buffer spring provides elastic support force, absorbing the impact generated by non-uniform motion; the double-spring symmetrical support structure balances the force, keeping the detection interval constant at 5-8mm. The guide rod limits the linear movement of the buffer spring.

[0020] A preferred embodiment of the oil pipe corrosion detection device with an integrated magnetic flux sensor on a non-uniform motion plunger is that the data processing and transmission module is built into the plunger body, including an embedded processor, a signal conditioning circuit, a wireless transmission unit, and a power supply unit. The input terminal of the signal conditioning circuit is connected to the magnetic flux detection module and the motion sensing module, and the output terminal is connected to the embedded processor. The embedded processor is connected to the wireless transmission unit. The power supply unit supplies power to the signal conditioning circuit, the embedded processor, and the wireless transmission unit.

[0021] By adopting the above technical solution, the signal conditioning circuit amplifies, filters, and performs analog-to-digital conversion on the sensor signal; the embedded processor runs a compensation algorithm to identify defects; the wireless transmission unit uploads the detection results to the ground in real time; and the power supply unit provides a stable power supply to each module to achieve continuous detection.

[0022] Secondly, this application also proposes a method for detecting corrosion in oil pipes, and adopts the following technical solution.

[0023] A method for detecting oil pipe corrosion employs the aforementioned oil pipe corrosion detection device with a non-uniform motion plunger integrated magnetic flux sensor to detect oil pipe corrosion. The oil pipe corrosion detection method includes: Step 1: Adjust the straightening buffer module so that the detection distance between the magnetic flux detection module and the inner wall of the oil pipe is 5-8mm, and set the clock of the magnetic flux detection module and the motion sensing module to be synchronized.

[0024] Step 2: The plunger body moves at a non-uniform speed of 3-5 m / s in the oil pipe. The magnetic flux detection module collects the original magnetic flux leakage signal, and the motion sensing module collects the motion speed signal and axial displacement signal in real time.

[0025] Step 3: Calculate the velocity fluctuation coefficient, perform velocity distortion correction and baseline drift suppression on the original signal, and obtain the effective magnetic flux leakage signal.

[0026] Step 4: Extract the characteristic parameters of the effective magnetic flux leakage signal, match them with the defect feature library to identify the type of corrosion defect, and mark the signal segment corresponding to the corrosion defect as the defect feature signal.

[0027] Step 5: Time-match the defect feature signal with the axial displacement signal to determine the axial position of the corrosion defect and calculate the size parameters of the corrosion defect.

[0028] Step 6: Upload the test data and generate a test report.

[0029] By adopting the above technical solution, a complete detection process is achieved through 6 steps, from device debugging, signal acquisition, compensation processing, defect identification, positioning and quantification to data reporting, enabling online corrosion detection of the plunger under non-uniform motion at 3-5 m / s.

[0030] A preferred embodiment of this oil pipe corrosion detection method is that the velocity distortion correction of the original signal in step 3 is performed using the formula... The amplitude-corrected signal is calculated. , where the parentheses are This represents the k-th sampling point. The original magnetic flux leakage signal acquired by the magnetic flux detection module. The reference correction coefficient is the velocity fluctuation coefficient. , The motion sensing module collects motion speed signals in real time. The average speed detected by the motion sensing module within one detection cycle.

[0031] By adopting the above technical solution, the signal amplification factor is dynamically adjusted by the reciprocal of the speed fluctuation coefficient, eliminating the influence of speed changes on the signal amplitude, so that the output amplitude of the same defect remains consistent at different speeds, thus ensuring the accuracy of wall thickness reduction quantification.

[0032] A preferred embodiment of this oil pipe corrosion detection method is as follows: The baseline drift suppression in step 3 specifically involves: first, using a moving average filter to extract the trend line. , The width of the sliding window is then corrected using the rate of change of velocity. , For the estimated baseline drift, For acceleration influence coefficient, The sampling time interval is the time interval from which the baseline is subtracted from the correction signal. The compensated effective magnetic flux leakage signal is obtained. .

[0033] By adopting the above technical solution, the signal's slow changing trend is extracted through moving average filtering, and then the influence of inertial force is corrected and compensated by acceleration. Finally, the baseline is subtracted to flatten the signal, so that the defect signal characteristics are clearly presented on a stable baseline, thereby improving the accuracy of defect identification.

[0034] A preferred embodiment of the oil pipe corrosion detection method is that the characteristic parameters in step 4 include the amplitude, peak value, pulse width, and slope of the signal, and the defect feature library contains characteristic thresholds for wall thinning, pitting, and cracks.

[0035] By adopting the above technical solution, and through the combination of four characteristic parameters—amplitude, peak value, pulse width, and slope—it is possible to distinguish three different types of corrosion defects: wall thickness reduction, pitting, and cracking, thereby achieving automatic identification of defect types.

[0036] A preferred embodiment of this oil pipe corrosion detection method is that the calculation of the size parameters of the corrosion defects in step 5 includes: Wall thickness reduction rate calculation: ,in, This is the original wall thickness of the oil pipe. The amplitude of the leakage magnetic signal. For amplitude and wall thickness calibration coefficients, The wall thickness reduction rate; Pitting diameter calculation: ,in, The equivalent diameter of pitting corrosion. The instantaneous velocity of the plunger as it passes through the defect. For the signal time-domain pulse width, This is the pitting shape correction factor; Crack length calculation: ,in, The length of the crack. The number of sensor channels that trigger the limit This represents the spacing between adjacent sensor channels.

[0037] By adopting the above technical solution, the amplitude of the leakage magnetic signal is converted into the wall thickness reduction amount through the amplitude-wall thickness calibration model, thereby realizing the quantification of the thinning rate (error ≤ ±0.1mm); the pitting diameter is calculated by combining the product of velocity and time-domain pulse width with shape correction; and the crack length is calculated by multiplying the number of trigger channels by the channel spacing, thereby realizing the accurate quantification of the three defect sizes.

[0038] In summary, the oil pipe corrosion detection device and method based on the non-uniform motion plunger integrated magnetic flux sensor of this application have the following beneficial effects: With strong adaptability to working conditions, it realizes the integrated integration of magnetic flux sensor and plunger, without the need for additional traction equipment. The magnetic flux sensor can complete online corrosion detection of oil pipe under non-uniform speed motion of 3-5 m / s along with the plunger discharge process, and the detection efficiency is 2-3 times higher than that of traditional low-speed detection.

[0039] It has high detection accuracy. By designing a dynamic compensation algorithm for non-uniform signals, it eliminates magnetic flux signal distortion and baseline drift caused by speed fluctuations. The defect identification accuracy is ≥95%, and the wall thickness reduction quantization error is ≤±0.1mm, effectively reducing the rate of missed detection and false detection.

[0040] With high structural reliability, the detection spacing is kept constant under non-uniform motion through the straightening buffer module, avoiding collision between the sensor and the inner wall of the tubing. The sealing protection module is suitable for harsh working conditions such as 120℃ high temperature, 30MPa high pressure, and H2S concentration ≤3000ppm high sulfur content in the wellbore. The device has a continuous working stability of ≥98%.

[0041] With precise positioning, the motion sensing module and the magnetic flux detection module synchronize their clocks to achieve real-time matching of velocity, displacement, and magnetic flux signals. The axial positioning error of corrosion defects is ≤ ±0.5 meters, providing a location basis for precise oil pipe maintenance.

[0042] With strong endurance and powered by high-temperature resistant lithium batteries, it can achieve continuous online detection for 8 hours, meeting the batch detection needs of oil and gas fields and reducing the time and labor costs of on-site detection. Attached Figure Description

[0043] Figure 1 This is a schematic diagram of an oil pipe corrosion detection device that integrates a magnetic flux sensor with a non-uniformly moving plunger.

[0044] Figure 2 This is a top view of the buffer module for straightening.

[0045] Reference numerals: 1. Plunger body; 2. Magnetic flux detection module; 3. Centralizing buffer module; 4. Oil pipe; 21. Magnetization unit; 22. Magnetic flux sensor array; 31. Centralizing wheel; 32. Buffer spring; 33. Annular spring seat; 34. Wheel axle; 35. Guide rod; 11. Guide hole; 12. Guide tube; 211. N pole magnetic ring; 212. S pole magnetic ring; 213. Magnetic strip. Detailed Implementation

[0046] The technical solutions in the embodiments are described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the following embodiments, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0047] like Figure 1 A tubing corrosion detection device integrating a magnetic flux sensor with a non-uniform motion plunger is disclosed. This device is integrated into the plunger body of the plunger in the plunger drainage process and is suitable for non-uniform plunger motion conditions of 3-5 m / s. The tubing corrosion detection device includes a plunger body 1, a magnetic flux detection module 2, a motion sensing module, a centering buffer module 3, a sealing protection module, and a data processing and transmission module.

[0048] The plunger body 1 is a hollow cylindrical structure made of high-strength corrosion-resistant alloy material. It has a hollow mounting cavity inside and several grooves on the outer wall for fixing multiple functional modules.

[0049] The magnetic flux detection module 2 is circumferentially distributed in the upper part of the plunger body 1, and includes a magnetization unit 21 and a magnetic flux sensor array 22.

[0050] The magnetization unit 21 includes an N-pole magnetic ring 211, an S-pole magnetic ring 212, and several magnetic strips 213, which are respectively sleeved on the outer wall of the plunger body 1. The N-pole magnetic ring 211 and the S-pole magnetic ring 212 are arranged axially opposite to each other. The several magnetic strips 213 are evenly distributed circumferentially, and the two ends of each magnetic strip 213 are connected to the N-pole magnetic ring 211 and the S-pole magnetic ring 212, respectively, forming a closed magnetic circuit.

[0051] The magnetic flux sensor array 22 employs Hall effect sensors or magnetoresistive sensors, with a quantity of 6-12, which are circumferentially and uniformly embedded in the groove on the outer wall of the plunger body 1 between the N-pole magnetic ring 211 and the S-pole magnetic ring 212. Each magnetic flux sensor is located between two adjacent magnetic strips 213, and the surface of the magnetic flux sensor is flush with the outer wall of the plunger body 1. The sampling frequency of the magnetic flux sensor is ≥1000Hz.

[0052] The motion sensing module is integrated into the hollow mounting cavity of the plunger body 1. It includes an inertial measurement unit with a built-in three-axis accelerometer and a three-axis gyroscope for measuring the real-time motion speed and axial displacement of the plunger.

[0053] The motion sensing module and the magnetic flux detection module 2 share the same high-precision crystal oscillator as the clock source to achieve microsecond-level clock synchronization.

[0054] The straightening buffer module 3 consists of two sets, which are respectively located at the upper and lower parts of the plunger body 1.

[0055] Each set of straightening and buffer modules 3 includes an annular spring seat 33, several straightening wheels 31, wheel axles 34, buffer springs 32, and guide rods 35.

[0056] The annular spring seat 33 is embedded in the annular groove on the outer wall of the plunger body 1.

[0057] like Figure 2 Each set of centering wheels 31 is evenly distributed around the circumference, with a quantity of 3-4. The centering wheels 31 are made of wear-resistant polyurethane material and are cylindrical or drum-shaped.

[0058] A wheel axle 34 rotatably passes through the center hole of the centering wheel 31. Each end of the wheel axle 34 is connected to one end of a buffer spring 32, and the other end of the buffer spring 32 is fixed to an annular spring seat 33. A guide rod 35 passes through the interior of the buffer spring 32.

[0059] Multiple guide holes 11 are provided on the side wall of the plunger body 1. Multiple guide tubes 12 are provided inside the plunger body 1, and one end of each guide tube 12 is fixed to the periphery of the guide hole 11.

[0060] One end of the guide rod 35 is fixed to one end of the axle 34, and the other end of the guide rod 35 passes through the guide hole 11 and slides appropriately within the guide tube 12. The guide rod 35 guides the buffer spring 32 to perform linear extension and retraction movements to prevent tilting or deviation during the extension and retraction process.

[0061] The centering wheel 31 floats radially outward under the elastic force of the buffer spring 32 and rolls in contact with the inner wall of the oil pipe 4, ensuring that the constant detection distance between the plunger body 1 and the inner wall of the oil pipe 4 is 5-8mm.

[0062] The sealing and protection module includes fluororubber sealing rings and polytetrafluoroethylene anti-corrosion coating. The sealing rings are located at the connection points of each module, with a protection level of IP68; the anti-corrosion coating is sprayed on the plunger body 1 and the outer wall of each functional module to withstand corrosive media with a temperature of 120℃, a pressure of 30MPa, and H2S≤3000ppm.

[0063] The data processing and transmission module is built into the hollow mounting cavity of the plunger body 1, and includes an embedded processor, a signal conditioning circuit, a wireless transmission unit, and a power supply unit.

[0064] The input of the signal conditioning circuit is connected to the magnetic flux detection module 2 and the motion sensing module, and the output is connected to the embedded processor. The signal conditioning circuit is used to amplify, filter, and convert the magnetic flux leakage signal from analog to digital.

[0065] An embedded processor connects to the wireless transmission unit. The embedded processor is an industrial-grade MCU with a built-in non-uniform signal compensation algorithm for distortion correction and baseline drift suppression of the original magnetic flux leakage signal. The wireless transmission unit uses a downhole low-power wireless communication protocol.

[0066] The power supply unit powers the signal conditioning circuitry, embedded processor, and wireless transmission unit. It uses a lithium battery resistant to 120°C to meet the power requirements for continuous 8-hour testing.

[0067] Based on the above-mentioned oil pipe corrosion detection device using a non-uniform motion plunger integrated magnetic flux sensor, this application proposes an oil pipe corrosion detection method using a non-uniform motion plunger integrated magnetic flux sensor, comprising the following steps.

[0068] Step 1: Pre-installation and commissioning of the device The various modules of the detection device are integrated into the plunger body, with a detection interval of 5-8mm; each functional module is powered on and debugged to achieve microsecond-level synchronization between the motion sensing module and the magnetic flux detection module using the same clock source, and the magnetic flux sensor acquisition frequency is set to ≥1000Hz.

[0069] Step 2: Synchronization signal acquisition A plunger equipped with a detection device is lowered into the oil pipe to be tested, causing it to undergo a non-uniform axial movement of 3-5 meters per second during the plunger drainage process.

[0070] The original signal of magnetic flux leakage in the oil pipe wall is collected in real time by the magnetic flux detection module. The real-time velocity signal of the plunger is synchronously acquired by the inertial measurement unit of the motion sensing module. and axial displacement signal The sampling frequency is consistent with that of the magnetic flux detection module.

[0071] After being preprocessed by the signal conditioning circuit, the three types of signals are transmitted to the embedded processor in real time and aligned according to the same timestamp.

[0072] Step 3: Dynamic compensation for non-uniform signals The embedded processor invokes its built-in non-uniform signal compensation algorithm and processes the signal in the following sub-steps: Sub-step 3.1: Calculate the velocity fluctuation coefficient , The part inside the parentheses This represents the k-th sampling point. The motion sensing module collects motion speed signals in real time. The average speed within the detection period is measured, and the speed fluctuation coefficient ranges from 0.7 to 1.3.

[0073] Sub-step 3.2: Velocity distortion correction (amplitude compensation) , in, This is the signal after amplitude correction. This is the raw signal of magnetic flux leakage collected by the magnetic flux detection module. This is the baseline correction factor (obtained through laboratory calibration, typically 1.0).

[0074] Sub-step 3.3: Baseline drift suppression First, a moving average filter is used to extract the baseline trend: ,in, The width of the sliding window is half its width. Then correct using the rate of change of velocity (acceleration): , in, For the estimated baseline drift, This is the acceleration influence coefficient (experimentally calibrated, usually taken as 0.05-0.2). This represents the sampling time interval.

[0075] Finally, subtract the baseline from the corrected signal: , This is the effective magnetic flux leakage signal after compensation.

[0076] Step 4: Corrosion Defect Feature Extraction and Identification For the compensated effective magnetic flux leakage signal Extract the following feature parameters: Amplitude: The maximum value of the signal; Peak value: Local maximum; Pulse width: The duration of a signal exceeding half the peak height, converted into spatial length; Slope: The rate of change along the rising or falling edge.

[0077] The extracted feature parameters were matched with a pre-defined tubing corrosion defect feature library. This defect feature library was established through standard sample tube calibration experiments and includes feature threshold ranges for three typical defects: wall thinning, pitting, and cracking. Defect types Amplitude peak Pulse width slope Wall thickness reduction medium gentle Width Small pitting higher peak narrow Larger crack high Extreme extremely narrow great Based on the matching results, valid signals and their types that indicate corrosion defects are identified, while normal pipe wall signals without defects are excluded.

[0078] Step 5: Defect Localization and Quantification Sub-step 5.1: Axial positioning of the defect The identified effective signals of corrosion defects are combined with the synchronously acquired axial displacement signals. Time matching is performed to determine the precise axial position of corrosion defects in the tubing based on the real-time axial displacement trajectory of the plunger, with a positioning error of ≤ ±0.5 meters.

[0079] Sub-step 5.2: Calculation of wall thickness reduction rate , in, The original wall thickness of the oil pipe (mm). The amplitude of the leakage magnetic signal (mV) is given. The amplitude-wall thickness calibration factor (mm / mV) is used. The wall thickness reduction rate (%) is given, and the quantification error of the wall thickness reduction rate is ≤ ±0.1 mm.

[0080] Sub-step 5.3: Calculation of pitting diameter , in, The equivalent diameter of pitting (mm). The instantaneous velocity (mm / s) of the plunger as it passes through the defect. The pulse width (s) in the time domain of the signal. This is the pitting shape correction factor (with a value of 0.7-0.9).

[0081] Sub-step 5.4: Crack length calculation Using array sensor method: , in, The crack length is in mm. The number of sensor channels that trigger the limit The distance between adjacent sensor channels is (mm).

[0082] Step 6: Upload data and generate test report The embedded processor wirelessly transmits detection data, including the type of corrosion defects, axial location, wall thinning rate, pitting diameter, and crack length, to a ground monitoring terminal in real time. The ground monitoring terminal stores and visualizes the detection data and automatically generates a pipeline corrosion detection report. The report includes the location of defects, defect level, and treatment recommendations, providing data support for pipeline maintenance and replacement.

[0083] Application Example 1: Corrosion Detection of φ73mm Oil Pipe 1. Device parameter configuration The plunger body is made of N80 high-strength corrosion-resistant alloy.

[0084] The magnetic flux detection module is equipped with eight Hall sensors evenly distributed around the circumference, with a sampling frequency of 1000Hz.

[0085] The N-pole and S-pole magnetic rings are toroidal permanent magnets made of neodymium iron boron. The magnetic strips are made of strip-shaped pure iron.

[0086] The motion sensing module uses a MEMS-IMU (Micro-Electro-Mechanical System Inertial Measurement Unit) chip, which integrates a three-axis accelerometer and a three-axis gyroscope, and shares a 20MHz temperature-compensated crystal oscillator with the magnetic flux sensor.

[0087] The straightening buffer module is set up in two groups, upper and lower, with three polyurethane straightening wheels in each group. The buffer spring has an elastic coefficient of 5N / mm, is compatible with φ73mm oil pipe (inner diameter φ73mm), and has a detection spacing of 6mm.

[0088] The sealing and protection module uses a fluororubber sealing ring (IP68) + a 0.2mm thick polytetrafluoroethylene anti-corrosion coating.

[0089] Data processing uses an STM32 industrial-grade MCU, and wireless transmission uses a LoRa downhole communication module.

[0090] The power supply unit uses a 20000mAh high-temperature resistant lithium battery.

[0091] 2. Testing process After integrating the device into the plunger body, it is lowered into a φ73mm oil pipe. The plunger moves at a speed of 3-5 m / s with a speed fluctuation coefficient of 0.8-1.2. Simultaneously, magnetic flux leakage signals, velocity signals, and displacement signals are collected. Signal correction is completed through a non-uniform speed signal compensation algorithm. Defect features are extracted and matched with a feature library to achieve corrosion defect identification, location, and quantification.

[0092] 3. Test Results A total of 12 corrosion defects were identified, including 8 thinning defects and 4 pitting defects, with a defect identification accuracy of 96%. The quantitative error of thinning defects was ±0.08 mm, the quantitative error of pitting diameter was ±0.1 mm, and the axial positioning error of defects was ±0.4 meters. The device worked continuously for 8 hours without collisions or signal interruptions, and is suitable for well conditions of 100℃, 25MPa, and H2S concentration of 2000ppm.

[0093] Application Example 2: Corrosion Detection of φ89mm Oil Pipe 1. Device parameter configuration The magnetic flux detection module is equipped with 10 circumferentially distributed magnetoresistive sensors with a sampling frequency of 1200Hz; the centering buffer module is equipped with two sets, upper and lower, each set with 4 centering wheels, adapted to φ89mm tubing (inner diameter φ89mm), with a detection spacing of 7mm; the other device parameters are the same as in application example 1; the wellbore conditions to be tested are 110℃, 28MPa, and H2S concentration of 2800ppm.

[0094] 2. Testing process The plunger movement speed is 3-5 m / s, and the speed fluctuation coefficient is 0.7-1.3; the detection method of this application is used to complete signal acquisition, compensation, defect identification and quantification.

[0095] 3. Test Results A total of 15 corrosion defects were identified, with a defect identification accuracy rate of 97%; the wall thickness reduction quantification error was ±0.09mm, and the positioning error was ±0.45m; the device operated stably under high sulfur content conditions, and signal transmission was interference-free.

[0096] The above results demonstrate that the tubing corrosion detection device and method with integrated magnetic flux of non-uniform motion plunger provided in this application can achieve online, high-precision, and accurate positioning detection of tubing corrosion under non-uniform plunger motion of 3-5 m / s, while ensuring the reliability and stability of the device under harsh well conditions.

[0097] The above embodiments and application examples are only typical application cases of this application. Those skilled in the art can make adaptive adjustments to the number of sensors, the parameters of the centralizing buffer module, and the signal acquisition frequency of the device according to different tubing specifications and well conditions. All equivalent modifications or substitutions based on the technical solutions of this application fall within the protection scope of this application.

Claims

1. A pipe corrosion detection device with an integrated magnetic flux sensor for a non-uniformly moving plunger, characterized in that, It includes a plunger body (1), a magnetic flux detection module (2), a motion sensing module, a centering buffer module (3), and a data processing and transmission module; The plunger body (1) has a hollow structure; The magnetic flux detection module (2) is distributed on the outer periphery of the plunger body (1); the magnetic flux detection module (2) includes a magnetization unit (21) and a magnetic flux sensor array (22); the magnetization unit (21) is configured to generate a magnetic field to magnetize the wall of the oil pipe (4); the magnetic flux sensor array (22) is configured to collect magnetic flux leakage signals at corrosion defects in the oil pipe (4); The motion sensing module is integrated into the plunger body (1) and includes a speed measuring unit and a displacement measuring unit, which are used to collect the real-time motion speed and axial displacement of the plunger, and are synchronized with the clock of the magnetic flux detection module (2). The straightening buffer module (3) is disposed on the outer wall of the plunger body (1) and is used to adjust the detection distance between the magnetic flux sensor array (22) and the inner wall of the oil pipe (4) within the required range; The data processing and transmission module has a built-in embedded processor, which is configured to perform non-uniform signal compensation.

2. The oil pipe corrosion detection device with an integrated magnetic flux sensor for a non-uniform motion plunger according to claim 1, characterized in that, The magnetization unit (21) includes an N-pole magnetic ring (211), an S-pole magnetic ring (212), and a plurality of magnetic strips (213); the plurality of magnetic strips (213) are evenly distributed along the outer circumference of the plunger body (1); the N-pole magnetic ring (211) and the S-pole magnetic ring (212) are respectively sleeved on the outer wall of the plunger body (1) and arranged axially opposite each other; the two ends of each magnetic strip (213) are respectively connected to the N-pole magnetic ring (211) and the S-pole magnetic ring (212) to form a closed magnetic circuit; The magnetic flux sensor array (22) is disposed in the gap between adjacent magnetic strips (213).

3. The oil pipe corrosion detection device with an integrated magnetic flux sensor for a non-uniform motion plunger according to claim 2, characterized in that, The magnetic flux sensor array (22) is uniformly embedded in the groove of the outer wall of the plunger body (1) in the circumferential direction, and the outer surface of the magnetic flux sensor array (22) is flush with the outer wall of the plunger body (1).

4. The oil pipe corrosion detection device with an integrated magnetic flux sensor for a non-uniform motion plunger according to claim 1, characterized in that, The oil pipe corrosion detection device of the non-uniform motion plunger integrated magnetic flux sensor includes two sets of the centering buffer modules (3), which are respectively set on the upper and lower parts of the plunger body (1); each set of the centering buffer modules (3) includes several centering wheels (31), several buffer springs (32), annular spring seats (33), several wheel axles (34) and several guide rods (35); the annular spring seats (33) are embedded in the annular groove on the outer wall of the plunger body (1); the several centering wheels (31) move along the plunger The main body (1) is evenly distributed around its circumference; each of the axles (34) rotatably passes through the central hole of a centering wheel (31), and each end of the axle (34) is connected to one end of a buffer spring (32), and the other end of the buffer spring (32) is fixed to the annular spring seat (33); multiple guide holes (11) are opened on the side wall of the plunger body (1); multiple guide tubes (12) are provided inside the plunger body (1), and one end of each guide tube (12) is fixed to the periphery of the guide hole (11); The guide rod (35) passes through the interior of the buffer spring (32); one end of the guide rod (35) is fixed to one end of the wheel axle (34), and the other end of the guide rod (35) passes through the guide hole (11) and slides appropriately in the guide tube (12); the centering wheel (31) rolls in contact with the inner wall of the oil pipe (4), and the distance between the magnetic flux detection module (2) and the inner wall of the oil pipe (4) is 5-8mm.

5. The oil pipe corrosion detection device with an integrated magnetic flux sensor for a non-uniform motion plunger according to claim 1, characterized in that, The data processing and transmission module is built into the plunger body (1) and includes an embedded processor, a signal conditioning circuit, a wireless transmission unit and a power supply unit; The input terminal of the signal conditioning circuit is connected to the magnetic flux detection module (2) and the motion sensing module, and the output terminal is connected to the embedded processor; the embedded processor is connected to the wireless transmission unit; the power supply unit provides power to the signal conditioning circuit, the embedded processor and the wireless transmission unit.

6. A method for detecting corrosion in oil pipes, characterized in that, The oil pipe corrosion detection device using the non-uniform motion plunger integrated magnetic flux sensor as described in any one of claims 1-5 is used to detect oil pipe corrosion; the oil pipe corrosion detection method includes: Step 1: Adjust the straightening buffer module so that the detection distance between the magnetic flux detection module and the inner wall of the oil pipe is 5-8mm, and set the clock of the magnetic flux detection module and the motion sensing module to be synchronized. Step 2: The plunger body moves at a non-uniform speed of 3-5 m / s in the oil pipe. The magnetic flux detection module collects the original magnetic flux leakage signal, and the motion sensing module collects the motion speed signal and axial displacement signal in real time. Step 3: Calculate the velocity fluctuation coefficient, perform velocity distortion correction and baseline drift suppression on the original signal to obtain the effective magnetic flux leakage signal; Step 4: Extract the feature parameters of the effective magnetic flux leakage signal, match them with the defect feature library to identify the type of corrosion defect, and mark the signal segment corresponding to the corrosion defect as the defect feature signal; Step 5: Time-match the defect feature signal and the axial displacement signal to determine the axial position of the corrosion defect and calculate the size parameters of the corrosion defect; Step 6: Upload the test data and generate a test report.

7. The method for detecting oil pipe corrosion according to claim 6, characterized in that, Step 3, which involves correcting the velocity distortion of the original signal, uses the formula... The amplitude-corrected signal is calculated. , where the parentheses are This represents the k-th sampling point. The original magnetic flux leakage signal acquired by the magnetic flux detection module. The reference correction coefficient is the velocity fluctuation coefficient. , The motion sensing module collects motion speed signals in real time. The average speed detected by the motion sensing module within one detection cycle.

8. The method for detecting oil pipe corrosion according to claim 7, characterized in that, The baseline drift suppression mentioned in step 3 specifically involves: first, using a moving average filter to extract the trend line. , The width of the sliding window is then corrected using the rate of change of velocity. , For the estimated baseline drift, For acceleration influence coefficient, The sampling time interval is the time interval from which the baseline is subtracted from the correction signal. The compensated effective magnetic flux leakage signal is obtained. .

9. The method for detecting oil pipe corrosion according to claim 6, characterized in that, The characteristic parameters mentioned in step 4 include the amplitude, peak value, pulse width, and slope of the signal, and the defect feature library contains feature thresholds for wall thinning, pitting, and cracks.

10. The method for detecting oil pipe corrosion according to claim 6, characterized in that, Step 5 involves calculating the dimensional parameters of the corrosion defects, including: Wall thickness reduction rate calculation: ,in, This is the original wall thickness of the oil pipe. The amplitude of the leakage magnetic signal. For amplitude and wall thickness calibration coefficients, The wall thickness reduction rate; Pitting diameter calculation: ,in, The equivalent diameter of pitting corrosion. The instantaneous velocity of the plunger as it passes through the defect. For the signal time-domain pulse width, This is the pitting shape correction factor; Crack length calculation: ,in, The length of the crack. The number of sensor channels that trigger the limit This represents the spacing between adjacent sensor channels.

Images