Oil and gas pipeline pulse excitation eddy current and magnetic flux leakage composite detection device and method

Abstract

The application discloses an oil and gas pipeline pulse excitation eddy current and magnetic flux leakage composite detection device and method, relates to the internal detection technical field of an oil and gas pipeline, and comprises a pulse excitation probe. The pulse excitation probe comprises a magnet, a first yoke, a second yoke, an excitation coil, a first receiving coil, a second receiving coil and a magnetic sensor. The magnet, the first yoke and the second yoke are used for applying a static magnetic field to the inner surface of the oil and gas pipeline. The excitation coil is used for being applied with a pulse voltage signal. When the pulse voltage signal is at a high level, the inner surface of the oil and gas pipeline is in a saturated magnetization state. The magnetic sensor is used for realizing magnetic flux leakage detection. When the pulse voltage signal is at a rising edge and a falling edge, the inner surface of the oil and gas pipeline generates a first eddy current field and a second eddy current field. The first receiving coil and the second receiving coil are used for realizing eddy current detection. The application can comprehensively utilize the advantages of magnetic flux leakage detection and eddy current detection, and realizes oil and gas pipeline defect detection.

Description

Technical Field

[0001] This application relates to the field of internal detection technology for oil and gas pipelines, and in particular to a pulse excitation eddy current and leakage magnetic flux composite detection device and method for oil and gas pipelines. Background Technology

[0002] Oil and gas pipelines operate in harsh environments, and are prone to defects due to pressure fluctuations in the transported medium, changes in ambient temperature, third-party damage, and erosion and corrosion by the medium.

[0003] Magnetic flux leakage (MFL) testing is sensitive to corrosion, a volumetric defect, and provides reliable results. It is the most widely used technique in pipeline inspection and is considered the cornerstone of the industry. However, traditional MFL testing equipment is bulky, heavy, and has a large magnetic attraction force. The medium in low-pressure, low-displacement oil and gas pipelines makes it difficult to drive the equipment, thus limiting its application in this area. Furthermore, due to the limitations of the MFL testing mechanism, while MFL testing can detect cracks with large angles to the magnetic field lines, it struggles to detect cracks with small angles.

[0004] Eddy current testing technology has a certain ability to detect both corrosion and crack defects, capable of detecting both large and small angles with magnetic field lines. However, due to the skin effect, traditional eddy current internal testing equipment can only detect defects on the inner surface of oil and gas pipelines, lacking sufficient ability to detect the depth of defects. Summary of the Invention

[0005] The purpose of this application is to provide a pulsed excitation eddy current and magnetic flux leakage composite detection device and method for oil and gas pipelines, which can combine the advantages of magnetic flux leakage detection and eddy current detection, and simultaneously detect corrosion and crack defects on the inner surface and outer surface of oil and gas pipelines. It is small in size, light in weight, and has a wide range of applications. The eddy current penetration depth is increased, enabling the detection of deeper internal surface corrosion and crack defects.

[0006] To achieve the above objectives, this application provides the following solution.

[0007] In a first aspect, this application provides a pulsed excitation eddy current and leakage magnetic flux composite detection device for oil and gas pipelines. The pulsed excitation eddy current and leakage magnetic flux composite detection device for oil and gas pipelines includes: a pulsed excitation probe, which includes a magnet, a first yoke, a second yoke, an excitation coil, a first receiving coil, a second receiving coil, and a magnetic sensor.

[0008] The first end of the first yoke, which is away from the inner surface of the oil and gas pipeline, is fixedly installed at the first end of the magnet, and the first end of the second yoke, which is away from the inner surface of the oil and gas pipeline, is fixedly installed at the second end of the magnet; the magnet, the first yoke, and the second yoke are used to apply a static magnetic field to the inner surface of the oil and gas pipeline.

[0009] The excitation coil is sleeved on the magnet; the excitation coil is used to be applied a pulse voltage signal. When the pulse voltage signal is at a high level, the excitation coil is used to generate an electromagnetic field. The electromagnetic field and the static magnetic field are in the same direction, so that the inner surface of the oil and gas pipeline is in a saturated magnetization state. When the pulse voltage signal is at the rising edge and falling edge, the excitation coil is used to generate a first eddy current field at the position corresponding to the first yoke on the inner surface of the oil and gas pipeline, and a second eddy current field at the position corresponding to the second yoke.

[0010] The first receiving coil is sleeved in the first yoke at the second end near the inner surface of the oil and gas pipeline, and the second receiving coil is sleeved in the second yoke at the second end near the inner surface of the oil and gas pipeline. The first receiving coil is used to receive the induced magnetic field generated by the first eddy current field and output a first voltage signal. The second receiving coil is used to receive the induced magnetic field generated by the second eddy current field and output a second voltage signal, thereby realizing eddy current detection.

[0011] The magnetic sensor is located between the first receiving coil and the second receiving coil; the magnetic sensor is used to receive the induced magnetic field generated on the inner surface of the oil and gas pipeline in a saturated magnetized state, and output a voltage signal to realize magnetic leakage detection.

[0012] Optionally, the oil and gas pipeline pulse excitation eddy current and leakage magnetic flux composite detection device further includes: an integrated electronic system, which includes a pulse signal generation module, a pre-amplifier module, a low-pass signal conditioning module, a high-pass signal conditioning module, and a data acquisition and storage module.

[0013] The pulse signal generating module is used to generate pulse signals.

[0014] The preamplifier module is connected to the pulse signal generation module and the excitation coil respectively; the preamplifier module is used to amplify the pulse signal to obtain a pulse voltage signal, and apply the pulse voltage signal to the excitation coil.

[0015] The low-pass signal conditioning module is connected to the magnetic sensor; the low-pass signal conditioning module is used to perform low-pass filtering and amplification on the voltage signal to obtain a low-pass conditioned signal.

[0016] The high-pass signal conditioning module is connected to the first receiving coil and the second receiving coil respectively; the high-pass signal conditioning module is used to perform differential processing on the first voltage signal and the second voltage signal to obtain a differential signal, and to perform high-pass filtering and amplification on the differential signal to obtain a high-pass conditioned signal.

[0017] The data acquisition and storage module is connected to the low-pass signal conditioning module and the high-pass signal conditioning module respectively; the data acquisition and storage module is used to acquire and store the low-pass conditioned signal and the high-pass conditioned signal.

[0018] Optionally, the low-pass signal conditioning module includes a low-pass filter unit and a first amplification unit.

[0019] The low-pass filter unit is connected to the magnetic sensor; the low-pass filter unit is used to perform low-pass filtering on the voltage signal to obtain a low-pass filtered signal.

[0020] The first amplification unit is connected to the low-pass filter unit and the data acquisition and storage module respectively; the first amplification unit is used to amplify the low-pass filtered signal to obtain the low-pass conditioned signal.

[0021] Optionally, the high-pass signal conditioning module includes a high-pass filter unit and a second amplification unit.

[0022] The high-pass filter unit is connected to the first receiving coil and the second receiving coil respectively; the high-pass filter unit is used to perform differential processing on the first voltage signal and the second voltage signal to obtain a differential signal, and to perform high-pass filtering on the differential signal to obtain a high-pass filtered signal.

[0023] The second amplification unit is connected to the high-pass filter unit and the data acquisition and storage module respectively; the second amplification unit is used to amplify the high-pass filtered signal to obtain a high-pass conditioned signal.

[0024] Optionally, the magnet is parallel to the axis of the oil and gas pipeline, the first yoke and the second yoke are both perpendicular to the magnet, the excitation coil is sleeved in the middle of the magnet, the magnetic sensor is located in the middle of the first receiving coil and the second receiving coil, and the magnetic sensor, the first receiving coil and the second receiving coil are all at the same distance from the inner surface of the oil and gas pipeline.

[0025] Optionally, eddy current testing can detect internal surface cracks and internal surface corrosion, while magnetic flux leakage testing can detect internal surface corrosion and external surface corrosion.

[0026] Optionally, there are multiple pulse excitation probes, and the multiple pulse excitation probes are arranged in an array.

[0027] There are multiple integrated electronic systems, and each integrated electronic system corresponds to one pulse excitation probe.

[0028] Optionally, the oil and gas pipeline pulse excitation eddy current and leakage magnetic flux composite detection device further includes: a detector frame and multiple probe arms, with one probe arm corresponding to one pulse excitation probe.

[0029] Multiple probe arms are fixedly mounted on the detector frame, and the multiple probe arms are arranged in an array; the pulse excitation probe is fixedly mounted on the probe arm; multiple integrated electronic systems are fixedly mounted on the detector frame.

[0030] Optionally, the detector frame is a circular cylinder, and the plurality of probe arms are evenly arranged along the circumference of the detector frame.

[0031] Secondly, this application provides a method for combined detection of pulsed excitation eddy current and leakage magnetic flux in oil and gas pipelines, which operates based on the aforementioned combined detection device for pulsed excitation eddy current and leakage magnetic flux in oil and gas pipelines. The method includes the following steps.

[0032] A static magnetic field is applied to the inner surface of the oil and gas pipeline using a magnet, a first yoke, and a second yoke.

[0033] A pulse voltage signal is applied to the excitation coil. When the pulse voltage signal is at a high level, the excitation coil generates an electromagnetic field. The electromagnetic field and the static magnetic field are in the same direction, so that the inner surface of the oil and gas pipeline is in a saturated magnetization state. When the pulse voltage signal is at the rising edge and falling edge, the excitation coil generates a first eddy current field at the position corresponding to the first yoke on the inner surface of the oil and gas pipeline, and generates a second eddy current field at the position corresponding to the second yoke.

[0034] The first receiving coil receives the induced magnetic field generated by the first eddy current field and outputs a first voltage signal. The second receiving coil receives the induced magnetic field generated by the second eddy current field and outputs a second voltage signal, thereby realizing eddy current detection.

[0035] A magnetic sensor is used to receive the induced magnetic field generated on the inner surface of an oil and gas pipeline that is in a saturated magnetized state, and outputs a voltage signal to realize magnetic leakage detection.

[0036] According to the specific embodiments provided in this application, this application has the following technical effects.

[0037] This application provides a pulse-excited eddy current and leakage magnetic field composite detection device and method for oil and gas pipelines. The device includes a pulse-excited probe comprising a magnet, a first yoke, a second yoke, an excitation coil, a first receiving coil, a second receiving coil, and a magnetic sensor. The magnet, the first yoke, and the second yoke are used to apply a static magnetic field to the inner surface of the oil and gas pipeline. The excitation coil is used to receive a pulse voltage signal. When the pulse voltage signal is at a high level, the excitation coil generates an electromagnetic field. The electromagnetic field and the static magnetic field are in the same direction, causing the inner surface of the oil and gas pipeline to be in a saturated magnetized state. At this time, the magnetic sensor receives the induced magnetic field generated by the saturated magnetized inner surface of the oil and gas pipeline and outputs a voltage signal to achieve leakage magnetic field detection. When the pulse voltage signal is at its rising and falling edges, the excitation coil generates a first eddy current field at the position corresponding to the first yoke and a second eddy current field at the position corresponding to the second yoke on the inner surface of the oil and gas pipeline. At this time, the first receiving coil receives the induced magnetic field generated by the first eddy current field and outputs a first voltage signal, and the second receiving coil receives the induced magnetic field generated by the second eddy current field and outputs a second voltage signal to achieve eddy current detection. The pulse-excitation eddy current and magnetic flux leakage composite detection device for oil and gas pipelines designed in this application can simultaneously realize magnetic flux leakage detection and eddy current detection, combining the advantages of both. It can simultaneously detect corrosion and crack defects on the inner surface of oil and gas pipelines as well as corrosion defects on the outer surface, and can detect crack defects with small angles to magnetic field lines. It uses an excitation coil to provide an electromagnetic field, which is superimposed with a static magnetic field to saturate the inner surface of the oil and gas pipeline. Compared with the method of saturating the inner surface of oil and gas pipelines entirely using a static magnetic field generated by a magnet, it can reduce the size and weight, and is suitable for low-pressure, low-displacement oil and gas pipelines. Therefore, it is small in size, light in weight, and has a wide range of applications. Because a static magnetic field is applied to the oil and gas pipeline during eddy current detection, the magnetic permeability of the oil and gas pipeline decreases. At this time, the eddy current penetration depth increases, and deeper inner surface corrosion and crack defects can be detected. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is a schematic diagram of the pulse excitation probe provided in Embodiment 1 of this application.

[0040] Figure 2 This is a three-dimensional structural diagram of the pulse excitation probe provided in Embodiment 1 of this application.

[0041] Figure 3This is a schematic diagram of the processing flow of the integrated electronic system provided in Embodiment 1 of this application.

[0042] Figure 4 This is a schematic diagram of the working process of the pulse excitation eddy current and leakage magnetic flux composite detection device for oil and gas pipelines provided in Embodiment 1 of this application.

[0043] Figure 5 This is a schematic diagram illustrating the working principle of the pulse excitation probe provided in Embodiment 1 of this application.

[0044] Figure 6 This is a schematic diagram of the electromagnetic field generated by the pulse excitation probe provided in Embodiment 1 of this application; wherein, Figure 6 (a) in the diagram represents the electromagnetic field generated when the voltage is high. Figure 6 (b) in the diagram represents the electromagnetic field generated when the voltage is low.

[0045] Figure 7 This is a schematic diagram illustrating the changes in magnetic field strength and permeability provided in Embodiment 1 of this application.

[0046] Figure 8 This is a schematic diagram of the structure of the pulse excitation eddy current and leakage magnetic flux composite detection device for oil and gas pipelines provided in Embodiment 1 of this application.

[0047] Reference numerals: 1-First magnet; 2-Second magnet; 3-First yoke; 4-Second yoke; 5-Excitation coil; 6-First receiving coil; 7-Second receiving coil; 8-Magnetic sensor; 9-Detector frame; 10-Probe arm; 11-Pulse excitation probe; 12-Integrated electronic system. Detailed Implementation

[0048] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0049] Example 1.

[0050] This embodiment provides a combined detection device for pulsed excitation eddy current and magnetic flux leakage in oil and gas pipelines, such as... Figure 1 and Figure 2 As shown, the oil and gas pipeline pulse excitation eddy current and leakage magnetic flux composite detection device includes: a pulse excitation probe, which includes a magnet, a first yoke 3, a second yoke 4, an excitation coil 5, a first receiving coil 6, a second receiving coil 7, and a magnetic sensor 8.

[0051] The first end of the first yoke 3, which is away from the inner surface of the oil and gas pipeline, is fixedly installed at the first end of the magnet. The first end of the second yoke 4, which is away from the inner surface of the oil and gas pipeline, is fixedly installed at the second end of the magnet. The magnet, the first yoke 3, and the second yoke 4 are used to apply a static magnetic field to the inner surface of the oil and gas pipeline.

[0052] The excitation coil 5 is mounted on the magnet. The excitation coil 5 is used to apply a pulse voltage signal. When the pulse voltage signal is at a high level, the excitation coil 5 is used to generate an electromagnetic field. The excitation coil 5, the first yoke 3, and the second yoke 4 are used to apply an electromagnetic field to the inner surface of the oil and gas pipeline. The electromagnetic field and the static magnetic field are in the same direction, so that the inner surface of the oil and gas pipeline is in a saturated magnetization state. When the pulse voltage signal is at the rising edge and falling edge, the excitation coil 5 is used to generate a first eddy current field at the position corresponding to the first yoke 3 on the inner surface of the oil and gas pipeline, and a second eddy current field at the position corresponding to the second yoke 4.

[0053] The first receiving coil 6 is sleeved in the first yoke 3 at the second end near the inner surface of the oil and gas pipeline, and the second receiving coil 7 is sleeved in the second yoke 4 at the second end near the inner surface of the oil and gas pipeline. The first receiving coil 6 is used to receive the induced magnetic field generated by the first eddy current field and output a first voltage signal. The second receiving coil 7 is used to receive the induced magnetic field generated by the second eddy current field and output a second voltage signal, thereby realizing eddy current detection.

[0054] The magnetic sensor 8 is located between the first receiving coil 6 and the second receiving coil 7. The magnetic sensor 8 is used to receive the induced magnetic field generated on the inner surface of the oil and gas pipeline in a saturated magnetized state, and output a voltage signal to realize leakage magnetic field detection.

[0055] In this embodiment, the magnet can be composed of multiple magnets, for example, such as Figure 1 As shown, the magnets include a first magnet 1 and a second magnet 2.

[0056] The core components of the pulse excitation probe in this embodiment include: a magnet, a first yoke 3, a second yoke 4, an excitation coil 5, a first receiving coil 6, a second receiving coil 7, and a magnetic sensor 8. The magnet provides a static magnetic field for the pulse excitation probe, reducing the permeability of the oil and gas pipeline and increasing the penetration depth of the eddy current field. The first yoke 3 and the second yoke 4 can guide the magnetic field generated by the magnet and the excitation coil 5 into the oil and gas pipeline, and are also part of a local magnetic circuit. The excitation coil 5 is the carrier for generating the pulsed magnetic field (including the electromagnetic field generated at high levels and the changing magnetic field generated at rising and falling edges), generating a pulsed magnetic field under the excitation of a pulsed voltage signal. The winding direction of the excitation coil 5 needs to ensure that the direction of the electromagnetic field generated by the excitation coil 5 when the level is high is consistent with the direction of the static magnetic field generated by the magnet. The winding direction of the first receiving coil 6 and the second receiving coil 7 is the same. When the excitation coil 5 generates a changing magnetic field at the rising and falling edges, causing the oil and gas pipeline to generate a first eddy current field and a second eddy current field, the first receiving coil 6 and the second receiving coil 7 respectively receive the induced magnetic field generated by the first eddy current field and the second eddy current field to realize eddy current detection. When the excitation coil 5 generates an electromagnetic field at a high level, causing the oil and gas pipeline to be in a saturated magnetization state, the magnetic sensor 8 receives the induced magnetic field that leaks into the space to realize magnetic leakage detection.

[0057] like Figure 3 As shown, the oil and gas pipeline pulse excitation eddy current and leakage magnetic flux composite detection device in this embodiment also includes an integrated electronic system, which includes a pulse signal generation module, a pre-amplifier module, a low-pass signal conditioning module, a high-pass signal conditioning module, and a data acquisition and storage module.

[0058] The pulse signal generation module is used to generate pulse signals, which can be square wave pulse signals.

[0059] The preamplifier module is connected to the pulse signal generation module and the excitation coil 5 respectively. The preamplifier module is used to amplify the pulse signal, provide energy to the pulse signal, obtain a pulse voltage signal, and apply the pulse voltage signal to the excitation coil 5 to drive the excitation coil 5 to generate a pulse magnetic field.

[0060] The low-pass signal conditioning module is connected to the magnetic sensor 8. The low-pass signal conditioning module is used to perform low-pass filtering and amplification on the voltage signal output by the magnetic sensor 8 to obtain the low-pass conditioned signal.

[0061] The high-pass signal conditioning module is connected to the first receiving coil 6 and the second receiving coil 7 respectively. The high-pass signal conditioning module is used to perform differential processing on the first voltage signal output by the first receiving coil 6 and the second voltage signal output by the second receiving coil 7 to obtain a differential signal, and then perform high-pass filtering and amplification on the differential signal to obtain a high-pass conditioned signal.

[0062] The data acquisition and storage module is connected to the low-pass signal conditioning module and the high-pass signal conditioning module respectively. The data acquisition and storage module is used to acquire and store the low-pass conditioned signal and the high-pass conditioned signal.

[0063] Considering that traditional eddy current detection equipment is severely affected by the lift-off effect during application, resulting in insufficient accuracy in defect detection, this embodiment designs differential processing, which can improve the detection accuracy.

[0064] The low-pass signal conditioning module includes a low-pass filter unit and a first amplification unit. The low-pass filter unit is connected to the magnetic sensor 8 and is used to perform low-pass filtering on the voltage signal output by the magnetic sensor 8 to obtain a low-pass filtered signal. The first amplification unit is connected to both the low-pass filter unit and the data acquisition and storage module. The first amplification unit is used to amplify the low-pass filtered signal to obtain a low-pass conditioned signal and then transmit the low-pass conditioned signal to the data acquisition and storage module.

[0065] The low-pass signal conditioning module in this embodiment includes two parts: low-pass filtering and amplification. The voltage signal input to the low-pass signal conditioning module by the magnetic sensor 8 contains high-frequency electromagnetic noise in the space, which can be filtered out by the low-pass filtering part. The low-frequency leakage magnetic field signal corresponding to the pipeline defect passes through, realizing leakage magnetic field detection.

[0066] The high-pass signal conditioning module includes a high-pass filter unit and a second amplification unit. The high-pass filter unit is connected to both the first receiving coil 6 and the second receiving coil 7. It performs differential processing on the first voltage signal output from the first receiving coil 6 and the second voltage signal output from the second receiving coil 7 to obtain a differential signal, and then performs high-pass filtering on the differential signal to obtain the high-pass filtered signal. The second amplification unit is connected to both the high-pass filter unit and the data acquisition and storage module. It amplifies the high-pass filtered signal to obtain the high-pass conditioned signal and then transmits the high-pass conditioned signal to the data acquisition and storage module.

[0067] The high-pass signal conditioning module in this embodiment includes two parts: high-pass filtering and amplification. The first voltage signal and the second voltage signal output by the first receiving coil 6 and the second receiving coil 7 are input into the high-pass signal conditioning module and first undergo differential processing. The resulting original differential signal contains low-frequency electromagnetic noise in the space, which can be filtered out by the high-pass filtering part. The high-frequency eddy current field signal corresponding to the pipe defect passes through, realizing eddy current detection.

[0068] In this embodiment, the magnet can be parallel to the axis of the oil and gas pipeline, the first yoke 3 and the second yoke 4 can both be perpendicular to the magnet, the excitation coil 5 can be sleeved in the middle of the magnet, the magnetic sensor 8 can be located in the middle of the first receiving coil 6 and the second receiving coil 7, and the distances from the magnetic sensor 8, the first receiving coil 6 and the second receiving coil 7 to the inner surface of the oil and gas pipeline can be the same.

[0069] In this embodiment, the pulse excitation probe may include a housing. After the magnet, the first yoke 3, the second yoke 4, the excitation coil 5, the first receiving coil 6, the second receiving coil 7, and the magnetic sensor 8 are installed in the housing, all components are completely cured with epoxy resin or other adhesives. During the detection process, the positions of the magnet, the first yoke 3, the second yoke 4, the excitation coil 5, the first receiving coil 6, the second receiving coil 7, and the magnetic sensor 8 remain unchanged.

[0070] like Figure 4 As shown in this embodiment, during detection, the pulse excitation eddy current and leakage magnetic flux composite detection device for oil and gas pipelines is placed inside the oil and gas pipeline to be tested. The magnet is used to generate a static magnetic field, and the first yoke 3 and the second yoke 4 are used to apply the static magnetic field generated by the magnet to the inner surface of the oil and gas pipeline. Therefore, the magnet, the first yoke 3 and the second yoke 4 are used to apply a static magnetic field to the inner surface of the oil and gas pipeline. The magnetic field strength of the static magnetic field is H1. At this time, a magnetic field loop is formed between the magnet, the first yoke 3, the second yoke 4 inside the pulse excitation probe and the local oil and gas pipeline covered by the magnet, the first yoke 3 and the second yoke 4, so that the inner surface of the oil and gas pipeline is in a static magnetized state, and the permeability of the local oil and gas pipeline covered by the magnet, the first yoke 3 and the second yoke 4 is reduced to μ1.

[0071] like Figure 5 and Figure 6 As shown, the excitation coil 5 is used to apply a pulse voltage signal, which is a curve showing the change of the excitation voltage over time. The pulse voltage signal includes a rising edge, a high level, a falling edge, and a low level. When the pulse voltage signal is at a high level, the excitation coil 5 generates an electromagnetic field with a magnetic field strength of H2. The direction of the electromagnetic field is the same as that of the static magnetic field. The excitation coil 5, the first yoke 3, and the second yoke 4 are used to apply the electromagnetic field to the inner surface of the oil and gas pipeline. In the local oil and gas pipeline covered by the magnet, the first yoke 3, and the second yoke 4, the electromagnetic field and the static magnetic field are vector-superimposed, and the magnetic field strength of the superimposed magnetic field reaches the saturation magnetization H. SThe inner surface of the oil and gas pipeline is saturated with magnetization, so that the inner surface of the oil and gas pipeline is in a saturated magnetization state. When the pulse voltage signal is at the rising edge and falling edge, that is, when the excitation coil 5 is applied with the rising edge and falling edge excitation voltage, the electromagnetic field generated by the excitation coil 5 will change transiently, that is, a changing magnetic field will be generated. According to Faraday's law of electromagnetic induction, two eddy current fields with opposite directions will be generated at the positions corresponding to the first yoke 3 and the second yoke 4 on the inner surface of the oil and gas pipeline. That is, the first eddy current field and the second eddy current field will be generated on the inner surface of the oil and gas pipeline. The position of the first eddy current field corresponds to the position of the first yoke 3, and the position of the second eddy current field corresponds to the position of the second yoke 4, and the directions of the first eddy current field and the second eddy current field are opposite. When the pulse voltage signal is at a low level, the excitation coil 5 does not generate an electromagnetic field.

[0072] The induced magnetic fields generated by the first and second eddy current fields will hinder the changing trend of the electromagnetic field. When cracks and corrosion defects appear on the inner surface of the oil and gas pipeline, the magnetic flux in the first receiving coil 6 and the second receiving coil 7 changes, and corresponding first and second voltage signals are output. At this time, the first and second voltage signals are eddy current field signals. That is, the first receiving coil 6 is used to receive the induced magnetic field generated by the first eddy current field and output the first voltage signal, and the second receiving coil 7 is used to receive the induced magnetic field generated by the second eddy current field and output the second voltage signal. After the first and second voltage signals are differentially filtered, high-pass filtered, and amplified by the high-pass signal conditioning module, they are input to the data acquisition and storage module. The high-pass conditioned signal is used to detect cracks and corrosion defects on the inner surface of the oil and gas pipeline, realizing eddy current detection.

[0073] During eddy current testing, the inner surface of the oil and gas pipeline is in a static magnetized state, and the magnetic permeability is reduced to μ1. The eddy current will further penetrate into the inside of the pipe wall. Therefore, when performing eddy current testing, the eddy current field signal carries deeper defect information.

[0074] When volumetric defects such as internal and external surface corrosion exist, the internal magnetic field of the inner surface of the oil and gas pipeline, which is in a saturated magnetization state, leaks into the space. This magnetic field is captured by the magnetic sensor 8, which outputs a corresponding voltage signal. This voltage signal is the leakage magnetic field signal. That is, the magnetic sensor 8 is used to receive the induced magnetic field generated by the inner surface of the oil and gas pipeline in a saturated magnetization state and outputs a voltage signal. After the voltage signal is low-pass filtered and amplified by the low-pass signal conditioning module, it is input to the data acquisition and storage module. The obtained low-pass conditioned signal is used to detect volumetric defects and crack defects with large angles to magnetic lines of force in the oil and gas pipeline, thus realizing magnetic leakage detection.

[0075] like Figure 7The diagram illustrates the changes in permeability (μ) and magnetic flux density (B) of an oil and gas pipeline with magnetic field strength (H) during detection. When the pipeline is unmagnetized, the magnetic field strength and magnetic flux density are both zero, and the permeability is μ0. When the pipeline is statically magnetized, the magnetic field strength is H1, the magnetic flux density is B1, and the permeability decreases to μ1. When the pulse voltage signal is high, the generated electromagnetic field has a magnetic field strength of H2, and the pipeline is saturated magnetized. The magnetic field strength experienced by the pipeline is the vector superposition of H1 and H2, which is the saturation magnetization intensity H. S This is the leakage magnetic field detection stage, and the magnetic induction intensity is B. S The magnetic permeability further decreases. When the pulse voltage signal is at the rising edge and falling edge, two eddy current fields are generated on the surface of the oil and gas pipeline. At this time, it is the eddy current detection stage, the magnetic induction intensity is B1, and the magnetic permeability is μ1.

[0076] The formula for calculating the eddy current penetration depth is as follows:

[0077]

[0078] Where δ is the eddy current penetration depth; ρ is the resistivity of the conductor; f is the frequency of the alternating magnetic field; and μ is the permeability of the conductor.

[0079] Clearly, the eddy current penetration depth increases as the magnetic permeability decreases, proving that the pulse excitation probe of this embodiment has the advantage of increasing the eddy current penetration depth.

[0080] In this embodiment, the defects that can be detected by eddy current detection include internal surface crack defects and internal surface corrosion defects, and the defects that can be detected by magnetic flux leakage detection include internal surface corrosion defects and external surface corrosion defects. It can also detect internal surface crack defects and external surface crack defects with large angles to magnetic field lines.

[0081] Magnetic flux leakage (MFLL) internal testing equipment can detect volumetric defects such as internal and external corrosion in oil and gas pipelines. However, because the detection probe is separated from the pipe section magnetization device, with the probe positioned in the middle of the magnetization device, and the magnetization device saturates a section of the pipeline, the detection probe only extracts magnetic field information from the area it covers. Therefore, applying saturation magnetization to areas not covered by the probe is essentially a waste of magnetic field resources. Furthermore, the need for a large magnet for saturating a portion of the pipe section in MFLL internal testing equipment results in a large size and weight, making it difficult to apply to low-pressure, low-displacement oil and gas pipelines. Additionally, limitations in the detection mechanism make it difficult to detect crack defects with small angles to the magnetic field lines. Eddy current internal detection equipment can detect defects such as cracks and corrosion on the inner surface of oil and gas pipelines. It can detect both cracks with large and small angles to the magnetic field lines. However, since oil and gas pipelines are generally made of ferromagnetic materials with high magnetic permeability, the penetration depth of the eddy current is insufficient, making it difficult to detect deeper defects on the inner surface of oil and gas pipelines. To solve this problem, this embodiment combines the advantages of traditional magnetic flux leakage and eddy current detection technologies, proposing a pulse-excited eddy current and magnetic flux leakage composite detection device for oil and gas pipelines. The pipe section magnetization device (i.e., magnet and excitation coil 5) and the detection probe (i.e., magnetic sensor 8) are integrated together. A pulse excitation (i.e., pulse voltage signal) superimposed with a static magnetic field is used to apply saturation magnetization to the area covered by the detection probe. That is, saturation magnetization is applied only to the area covered by the detection probe, and magnetic field information is extracted, avoiding waste of magnetic field resources. When the pulse excitation is at a high level, the electromagnetic field of the excitation coil 5 and the static magnetic field of the magnet... The superposition of field phases applies saturation magnetization to the area covered by the detection probe. When volumetric defects are present, the magnetic sensor 8 captures changes in the leakage magnetic field in space, achieving leakage magnetic field detection. Compared to the method of saturating magnetization of the inner surface of oil and gas pipelines using a static magnetic field generated entirely by magnets, this method reduces volume and weight, making it suitable for low-pressure, low-displacement oil and gas pipelines with a wide range of applications. During the rising and falling edges of pulse excitation, the electromagnetic field of the excitation coil 5 undergoes transient changes, generating two eddy current fields in opposite directions on the inner surface of the oil and gas pipeline. This effectively detects cracks and corrosion defects in the pipeline's inner wall, achieving eddy current detection. Simultaneously, the presence of a static magnetic field in the probe-covered area reduces the magnetic permeability of the oil and gas pipeline, increasing the eddy current penetration depth and enabling the effective acquisition of deeper defect information within the pipeline's inner wall.

[0082] This embodiment has the following advantages.

[0083] (1) When saturation magnetization is applied to the oil and gas pipeline (static magnetic field + electromagnetic field in the high-level stage), saturation magnetization is applied only to the area covered by the probe. Therefore, compared with the traditional leakage magnetic field detection equipment that applies saturation magnetization to a part of the pipeline section, the waste of magnetic field resources is avoided and the volume and weight are significantly reduced.

[0084] (2) When the pulse excitation is in the rising and falling edge stages, the eddy field generated on the inner surface of the oil and gas pipeline will increase the eddy penetration depth due to the effect of the static magnetic field reducing the permeability, so that the eddy field signal carries deeper defect information.

[0085] (3) The pulse excitation probe combines the advantages of leakage magnetic field and eddy current technologies, which can detect cracks and internal and external corrosion defects in pipelines and determine the location of defects, thereby improving the efficiency and accuracy of pipeline internal detection.

[0086] In this embodiment, there are multiple pulse excitation probes arranged in an array. There are also multiple integrated electronic systems, with one integrated electronic system corresponding to one pulse excitation probe.

[0087] like Figure 8 As shown, the oil and gas pipeline pulse excitation eddy current and leakage flux composite detection device of this embodiment further includes: a detector frame 9 and multiple probe arms 10, with one probe arm 10 corresponding to one pulse excitation probe 11. Multiple probe arms 10 are all fixedly mounted on the detector frame 9, and the multiple probe arms 10 are arranged in an array. The pulse excitation probe 11 is fixedly mounted on the probe arm 10, and multiple integrated electronic systems 12 are all fixedly mounted on the detector frame 9.

[0088] In this embodiment, the detector frame 9 is a circular cylinder, and multiple probe arms 10 are evenly arranged along the circumference of the detector frame 9.

[0089] The detector frame 9 can be made of steel, providing an installation carrier and rigid support for the probe arm 10, integrated electronic system 12, etc. The probe arm 10 can be made of steel, connecting the pulse excitation probe 11 to the detector frame 9.

[0090] The pulse-excitation eddy current and magnetic leakage flux composite detection device for oil and gas pipelines proposed in this embodiment combines the advantages of both magnetic leakage flux and eddy current technologies. The placed magnets, along with the first yoke 3, the second yoke 4, and the local pipeline, form a magnetic circuit, allowing the probe to adhere closely to the pipe wall and reducing lift-off noise caused by probe jitter. Simultaneously, a static magnetic field is applied, reducing the permeability. During the high-level phase, precise saturation magnetization is applied to the area covered by the probe, conserving magnetic field resources and reducing size and weight, thus enabling the detection of volumetric defects on the inner and outer walls of oil and gas pipelines. During the rising and falling edges, eddy current detection is applied to the area covered by the probe, effectively detecting volumetric defects and cracks on the inner wall of the pipeline. Because eddy current detection is a superposition on a static magnetic field, the permeability of the pipeline decreases to μ1, increasing the penetration depth of the eddy currents, and the magnetic field excited by the eddy currents carries deeper defect information. Differential reception of the eddy current field signal using coils avoids the influence of probe lift-off and electromagnetic interference on the eddy current field signal, improving the accuracy of defect identification.

[0091] Example 2.

[0092] This embodiment provides a method for combined detection of pulsed excitation eddy current and leakage magnetic flux in oil and gas pipelines. It is based on the combined detection device for pulsed excitation eddy current and leakage magnetic flux in oil and gas pipelines described in Embodiment 1. The method for combined detection of pulsed excitation eddy current and leakage magnetic flux in oil and gas pipelines includes the following steps.

[0093] (1) Apply a static magnetic field to the inner surface of the oil and gas pipeline using a magnet, a first yoke, and a second yoke.

[0094] (2) Apply a pulse voltage signal to the excitation coil. When the pulse voltage signal is at a high level, the excitation coil generates an electromagnetic field. The electromagnetic field and the static magnetic field are in the same direction, so that the inner surface of the oil and gas pipeline is in a saturated magnetization state. When the pulse voltage signal is at the rising edge and falling edge, the excitation coil generates a first eddy current field at the position corresponding to the first yoke on the inner surface of the oil and gas pipeline, and generates a second eddy current field at the position corresponding to the second yoke.

[0095] (3) The first receiving coil is used to receive the induced magnetic field generated by the first eddy current field and output the first voltage signal. The second receiving coil is used to receive the induced magnetic field generated by the second eddy current field and output the second voltage signal to realize eddy current detection.

[0096] (4) Use a magnetic sensor to receive the induced magnetic field generated on the inner surface of the oil and gas pipeline in a saturated magnetized state, and output a voltage signal to realize magnetic leakage detection.

[0097] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0098] This document uses specific examples to illustrate the principles and implementation methods of this application. The descriptions of the above embodiments are only for the purpose of helping to understand the methods and core ideas of this application. Furthermore, those skilled in the art will recognize that, based on the ideas of this application, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. A combined detection device for pulsed excitation eddy current and leakage flux in oil and gas pipelines, characterized in that, The oil and gas pipeline pulse excitation eddy current and leakage magnetic flux composite detection device includes: a pulse excitation probe, which includes a magnet, a first yoke, a second yoke, an excitation coil, a first receiving coil, a second receiving coil, and a magnetic sensor; The first end of the first yoke, which is away from the inner surface of the oil and gas pipeline, is fixedly installed at the first end of the magnet, and the first end of the second yoke, which is away from the inner surface of the oil and gas pipeline, is fixedly installed at the second end of the magnet; the magnet, the first yoke, and the second yoke are used to apply a static magnetic field to the inner surface of the oil and gas pipeline, reduce the magnetic permeability of the oil and gas pipeline, and increase the penetration depth of the eddy current field; The excitation coil is sleeved on the magnet; the excitation coil is used to be applied a pulse voltage signal. When the pulse voltage signal is at a high level, the excitation coil is used to generate an electromagnetic field. The electromagnetic field and the static magnetic field are in the same direction, so that the inner surface of the oil and gas pipeline is in a saturated magnetization state. When the pulse voltage signal is at the rising edge and falling edge, the excitation coil is used to generate a first eddy current field at the position corresponding to the first yoke on the inner surface of the oil and gas pipeline, and generate a second eddy current field at the position corresponding to the second yoke. The first receiving coil is sleeved in the first yoke at the second end near the inner surface of the oil and gas pipeline, and the second receiving coil is sleeved in the second yoke at the second end near the inner surface of the oil and gas pipeline. The first receiving coil is used to receive the induced magnetic field generated by the first eddy current field and output a first voltage signal. The second receiving coil is used to receive the induced magnetic field generated by the second eddy current field and output a second voltage signal. Eddy current detection is realized based on the differential signal obtained by differential processing of the first voltage signal and the second voltage signal. The magnetic sensor is located between the first receiving coil and the second receiving coil; the magnetic sensor is used to receive the induced magnetic field generated on the inner surface of the oil and gas pipeline in a saturated magnetized state, output a voltage signal, and realize magnetic leakage detection based on the voltage signal.

2. The oil and gas pipeline pulse excitation eddy current and leakage flux composite detection device according to claim 1, characterized in that, The oil and gas pipeline pulse excitation eddy current and leakage magnetic flux composite detection device also includes: an integrated electronic system, which includes a pulse signal generation module, a pre-amplifier module, a low-pass signal conditioning module, a high-pass signal conditioning module, and a data acquisition and storage module; The pulse signal generating module is used to generate a pulse signal; The preamplifier power amplifier module is connected to the pulse signal generation module and the excitation coil respectively; the preamplifier power amplifier module is used to amplify the pulse signal to obtain a pulse voltage signal, and apply the pulse voltage signal to the excitation coil; The low-pass signal conditioning module is connected to the magnetic sensor; the low-pass signal conditioning module is used to perform low-pass filtering and amplification on the voltage signal to obtain a low-pass conditioned signal. The high-pass signal conditioning module is connected to the first receiving coil and the second receiving coil respectively; the high-pass signal conditioning module is used to perform differential processing on the first voltage signal and the second voltage signal to obtain a differential signal, and to perform high-pass filtering and amplification on the differential signal to obtain a high-pass conditioned signal; The data acquisition and storage module is connected to the low-pass signal conditioning module and the high-pass signal conditioning module respectively; the data acquisition and storage module is used to acquire and store the low-pass conditioned signal and the high-pass conditioned signal.

3. The oil and gas pipeline pulse excitation eddy current and leakage flux composite detection device according to claim 2, characterized in that, The low-pass signal conditioning module includes a low-pass filter unit and a first amplification unit; The low-pass filter unit is connected to the magnetic sensor; the low-pass filter unit is used to perform low-pass filtering on the voltage signal to obtain a low-pass filtered signal. The first amplification unit is connected to the low-pass filter unit and the data acquisition and storage module respectively; the first amplification unit is used to amplify the low-pass filtered signal to obtain the low-pass conditioned signal.

4. The oil and gas pipeline pulse excitation eddy current and leakage flux composite detection device according to claim 2, characterized in that, The high-pass signal conditioning module includes a high-pass filter unit and a second amplification unit; The high-pass filter unit is connected to the first receiving coil and the second receiving coil respectively; the high-pass filter unit is used to perform differential processing on the first voltage signal and the second voltage signal to obtain a differential signal, and to perform high-pass filtering on the differential signal to obtain a high-pass filtered signal; The second amplification unit is connected to the high-pass filter unit and the data acquisition and storage module respectively; the second amplification unit is used to amplify the high-pass filtered signal to obtain a high-pass conditioned signal.

5. The oil and gas pipeline pulse excitation eddy current and leakage flux composite detection device according to claim 1, characterized in that, The magnet is parallel to the axis of the oil and gas pipeline. The first yoke and the second yoke are both perpendicular to the magnet. The excitation coil is sleeved in the middle of the magnet. The magnetic sensor is located between the first receiving coil and the second receiving coil. The magnetic sensor, the first receiving coil, and the second receiving coil are all equidistant from the inner surface of the oil and gas pipeline.

6. The oil and gas pipeline pulse excitation eddy current and leakage flux composite detection device according to claim 1, characterized in that, Eddy current testing can detect internal surface cracks and internal surface corrosion, while magnetic flux leakage testing can detect internal surface corrosion and external surface corrosion.

7. The oil and gas pipeline pulse excitation eddy current and leakage flux composite detection device according to claim 2, characterized in that, There are multiple pulse excitation probes, and the multiple pulse excitation probes are arranged in an array. There are multiple integrated electronic systems, and each integrated electronic system corresponds to one pulse excitation probe.

8. The oil and gas pipeline pulse excitation eddy current and leakage flux composite detection device according to claim 7, characterized in that, The oil and gas pipeline pulse excitation eddy current and leakage magnetic flux composite detection device also includes: a detector frame and multiple probe arms, with one probe arm corresponding to one pulse excitation probe; Multiple probe arms are fixedly mounted on the detector frame, and the multiple probe arms are arranged in an array; the pulse excitation probe is fixedly mounted on the probe arm; multiple integrated electronic systems are fixedly mounted on the detector frame.

9. The oil and gas pipeline pulse excitation eddy current and leakage flux composite detection device according to claim 8, characterized in that, The detector frame is a circular cylinder, and multiple probe arms are evenly arranged along the circumference of the detector frame.

10. A method for combined detection of pulsed excitation eddy current and leakage flux in oil and gas pipelines, operating based on the combined detection device for pulsed excitation eddy current and leakage flux in oil and gas pipelines as described in any one of claims 1-9, characterized in that... The combined pulse excitation eddy current and magnetic flux leakage detection method for oil and gas pipelines includes: A static magnetic field is applied to the inner surface of the oil and gas pipeline using a magnet, a first yoke, and a second yoke. A pulse voltage signal is applied to the excitation coil. When the pulse voltage signal is at a high level, the excitation coil generates an electromagnetic field. The electromagnetic field and the static magnetic field are in the same direction, so that the inner surface of the oil and gas pipeline is in a saturated magnetization state. When the pulse voltage signal is at the rising edge and falling edge, the excitation coil generates a first eddy current field at the position corresponding to the first yoke on the inner surface of the oil and gas pipeline, and generates a second eddy current field at the position corresponding to the second yoke. The first receiving coil receives the induced magnetic field generated by the first eddy current field and outputs a first voltage signal; the second receiving coil receives the induced magnetic field generated by the second eddy current field and outputs a second voltage signal, thereby realizing eddy current detection. A magnetic sensor is used to receive the induced magnetic field generated on the inner surface of an oil and gas pipeline that is in a saturated magnetized state, and outputs a voltage signal to realize magnetic leakage detection.

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