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

Abstract

The invention discloses an oil and gas pipeline pulse excitation eddy current and magnetic flux leakage composite detection device and method, and relates to the technical field of oil and gas pipeline internal detection, the device 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 applying 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, and the magnetic sensor is used for realizing magnetic flux leakage detection; a first vortex field and a second vortex field are generated on the inner surface of the oil-gas pipeline, and vortex detection is achieved through the first receiving coil and the second receiving coil. The advantages of magnetic flux leakage detection and eddy current detection can be integrated, and oil and gas pipeline defect detection is achieved.

Description

Technical Field

[0001] This application relates to the technical field of in-line inspection of oil and gas pipelines, and particularly to a pulsed excitation eddy current and magnetic flux leakage composite inspection device and method for oil and gas pipelines. Background Art

[0002] The service scenarios of oil and gas pipelines are harsh. Due to reasons such as pressure difference fluctuations of the transported medium, environmental temperature changes, third-party damage, and medium erosion and corrosion, pipe body defects are likely to occur.

[0003] Magnetic flux leakage detection technology is sensitive to volumetric defects such as corrosion, and the detection results are reliable. It is one of the most widely used technologies in in-line pipeline inspection and is known as the cornerstone of the in-line pipeline inspection industry. However, the volume, weight, and magnetic attraction of traditional magnetic flux leakage in-line inspection equipment are huge, and the medium in low-pressure and low-displacement oil and gas pipelines is difficult to drive this magnetic flux leakage in-line inspection equipment, resulting in the inability of this magnetic flux leakage in-line inspection equipment to be applied to the inspection of low-pressure and low-displacement oil and gas pipelines. At the same time, limited by the magnetic flux leakage detection mechanism, magnetic flux leakage in-line inspection equipment can detect crack defects with a large included angle with the magnetic field lines, but it is difficult to detect crack defects with a small included angle with the magnetic field lines.

[0004] Eddy current detection technology has a certain detection ability for both corrosion and crack defects. It can detect both crack defects with a large included angle with the magnetic field lines and crack defects with a small included angle with the magnetic field lines. However, affected by the skin effect, traditional eddy current in-line inspection equipment can only detect inner surface defects of oil and gas pipelines and has insufficient detection ability for 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 inspection device and method for oil and gas pipelines, which can combine the advantages of magnetic flux leakage detection and eddy current detection, simultaneously detect inner surface corrosion and crack defects and outer surface corrosion defects of oil and gas pipelines, have a small volume, light weight, wide application range, increased eddy current penetration depth, and be able to detect deeper inner surface corrosion and crack defects.

[0006] To achieve the above purpose, the following solutions are provided in this application.

[0007] In a first aspect, this application provides a pulsed excitation eddy current and magnetic flux leakage composite inspection device for oil and gas pipelines. The pulsed excitation eddy current and magnetic flux leakage composite inspection device for oil and gas pipelines includes: a pulsed excitation probe, and the pulsed excitation probe 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 far 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 far 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 with a pulsed voltage signal. When the pulsed voltage signal is at a high level, the excitation coil is used to generate an electromagnetic field, and the direction of the electromagnetic field is the same as that of the static magnetic field, so that the inner surface of the oil and gas pipeline is in a saturated magnetization state. When the pulsed voltage signal is at the rising edge and the falling edge, the excitation coil is used to generate a first eddy current field at the position corresponding to the first yoke in 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 on the second end of the first yoke close to the inner surface of the oil and gas pipeline, and the second receiving coil is sleeved on the second end of the second yoke close to 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, and 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 to realize 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 by the inner surface of the oil and gas pipeline in the saturated magnetization state and output a voltage signal to realize magnetic flux leakage detection.

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

[0013] The pulse signal generation module is used to generate a pulse signal.

[0014] The pre-power amplification module is respectively connected to the pulse signal generation module and the excitation coil; the pre-power amplification module is used to amplify the pulse signal to obtain a pulsed voltage signal and apply the pulsed 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 respectively connected to the first receiving coil and the second receiving coil; the high-pass signal conditioning module is configured to perform differential processing on the first voltage signal and the second voltage signal to obtain a differential signal, and 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 respectively connected to the low-pass signal conditioning module and the high-pass signal conditioning module; the data acquisition and storage module is configured 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 filtering unit and a first amplification unit.

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

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

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

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

[0023] The second amplification unit is respectively connected to the high-pass filtering unit and the data acquisition and storage module; the second amplification unit is configured 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 distances from the magnetic sensor, the first receiving coil and the second receiving coil to the inner surface of the oil and gas pipeline are the same.

[0025] Optionally, the defects that can be detected by eddy current testing include inner surface crack defects and inner surface corrosion defects, and the defects that can be detected by magnetic flux leakage testing include inner surface corrosion defects and outer surface corrosion defects.

[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 one integrated electronic system corresponds to one pulse excitation probe.

[0028] Optionally, the pulsed excitation eddy current and magnetic flux leakage composite detection device for oil and gas pipelines further includes: a detector skeleton and multiple probe arms, and one probe arm corresponds to one pulse excitation probe.

[0029] The multiple probe arms are all fixedly installed on the detector skeleton, and the multiple probe arms are arranged in an array; the pulse excitation probe is fixedly installed on the probe arm; the multiple integrated electronic systems are all fixedly installed on the detector skeleton.

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

[0031] In a second aspect, the present application provides a method for pulsed excitation eddy current and magnetic flux leakage composite detection of oil and gas pipelines, which works based on the above-mentioned pulsed excitation eddy current and magnetic flux leakage composite detection device for oil and gas pipelines, and the method for pulsed excitation eddy current and magnetic flux leakage composite detection of oil and gas pipelines includes the following steps.

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

[0033] Apply a pulsed voltage signal to the excitation coil. When the pulsed voltage signal is at a high level, use the excitation coil to generate an electromagnetic field. The direction of the electromagnetic field is the same as that of the static magnetic field, so that the inner surface of the oil and gas pipeline is in a saturated magnetization state. When the pulsed voltage signal is at the rising edge and the falling edge, use the excitation coil to generate 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.

[0034] Use a first receiving coil to receive the induced magnetic field generated by the first eddy current field and output a first voltage signal, and use a second receiving coil to receive the induced magnetic field generated by the second eddy current field and output a second voltage signal to achieve eddy current detection.

[0035] Use a magnetic sensor to receive the induced magnetic field generated by the inner surface of the oil and gas pipeline in a saturated magnetization state and output a voltage signal to achieve magnetic flux leakage detection.

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

[0037] The present application provides an oil and gas pipeline pulsed excitation eddy current and magnetic flux leakage composite detection device and method, including a pulsed excitation probe. The pulsed excitation probe 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 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 be applied with a pulsed voltage signal. When the pulsed voltage signal is at a high level, the excitation coil is used to generate an electromagnetic field, and the direction of the electromagnetic field is the same as that of the static magnetic field, so that the inner surface of the oil and gas pipeline is in a saturated magnetization state. At this time, the magnetic sensor is used to receive the induced magnetic field generated by the inner surface of the oil and gas pipeline in the saturated magnetization state and output a voltage signal to achieve magnetic flux leakage detection. When the pulsed voltage signal is at the rising edge and the falling edge, the excitation coil is used to generate 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 in the inner surface of the oil and gas pipeline. At this time, 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, and 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 to achieve eddy current detection. The oil and gas pipeline pulsed excitation eddy current and magnetic flux leakage composite detection device designed by the present application can simultaneously achieve magnetic flux leakage detection and eddy current detection, can integrate the advantages of magnetic flux leakage detection and eddy current detection, simultaneously detect the inner surface corrosion and crack defects and the outer surface corrosion defects of the oil and gas pipeline, and can detect crack defects with a small included angle with the magnetic force line. Moreover, an excitation coil is used to provide an electromagnetic field, and this electromagnetic field is superimposed with the static magnetic field to saturate the magnetization of the inner surface of the oil and gas pipeline. Compared with the method of completely using the static magnetic field generated by the magnet to saturate the magnetization of the inner surface of the oil and gas pipeline, it can reduce the volume and weight, is applicable to low-pressure and low-displacement oil and gas pipelines, so it has a small volume, a light weight, and a wide application range. Since 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, and at this time, the eddy current penetration depth increases, and deeper inner surface corrosion and crack defects can be detected. Description of the Drawings

[0038] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0039] Figure 1 It is a schematic structural diagram of the pulsed excitation probe provided in Embodiment 1 of the present application.

[0040] Figure 2 It is a three-dimensional structural diagram of the pulsed excitation probe provided in Embodiment 1 of the present application.

[0041] Figure 3Schematic diagram of the processing flow of the integrated electronic system provided in Embodiment 1 of the present application.

[0042] Figure 4 Schematic diagram of the working process of the pulsed excitation eddy current and magnetic flux leakage composite detection device for oil and gas pipelines provided in Embodiment 1 of the present application.

[0043] Figure 5 Schematic diagram of the working principle of the pulsed excitation probe provided in Embodiment 1 of the present application.

[0044] Figure 6 Schematic diagram of the electromagnetic field generated by the pulsed excitation probe provided in Embodiment 1 of the present application; wherein, Figure 6 the (a) in it is the electromagnetic field generated at high level; Figure 6 the (b) in it is the electromagnetic field generated at low level.

[0045] Figure 7 Schematic diagram of the changes in magnetic field strength and magnetic permeability provided in Embodiment 1 of the present application.

[0046] Figure 8 Schematic diagram of the structure of the pulsed excitation eddy current and magnetic flux leakage composite detection device for oil and gas pipelines provided in Embodiment 1 of the present 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 - pulsed excitation probe; 12 - integrated electronic system. Detailed implementation manners

[0048] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0049] Embodiment 1.

[0050] This embodiment provides a pulsed excitation eddy current and magnetic flux leakage composite detection device for oil and gas pipelines, as Figure 1 and Figure 2 shown. The pulsed excitation eddy current and magnetic flux leakage composite detection device for oil and gas pipelines includes: a pulsed excitation probe, and the pulsed excitation probe 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 far 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 far 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 sleeved on the magnet. The excitation coil 5 is used to be applied with a pulsed voltage signal. When the pulsed 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 directions of the electromagnetic field and the static magnetic field are the same, so that the inner surface of the oil and gas pipeline is in a saturated magnetization state. When the pulsed voltage signal is at the rising edge and the falling edge, the excitation coil 5 is used to generate a first eddy current field at the position corresponding to the first yoke 3 and a second eddy current field at the position corresponding to the second yoke 4 in the inner surface of the oil and gas pipeline.

[0053] The first receiving coil 6 is sleeved on the second end of the first yoke 3 close to the inner surface of the oil and gas pipeline. The second receiving coil 7 is sleeved on the second end of the second yoke 4 close to 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 to achieve 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 by the inner surface of the oil and gas pipeline in the saturated magnetization state and output a voltage signal to achieve magnetic flux leakage detection.

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

[0056] The core components of the pulsed 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. Among them, the magnet provides a static magnetic field for the pulsed excitation probe, reduces the magnetic permeability of the oil and gas pipeline, and increases the penetration depth of the eddy current field. The first yoke 3 and the second yoke 4 can introduce the magnetic field generated by the magnet and the excitation coil 5 into the oil and gas pipeline and are also part of the local magnetic circuit. The excitation coil 5 is the carrier for generating a pulsed magnetic field (including the electromagnetic field generated at high levels and the changing magnetic fields generated during the rising and falling edges). Under the excitation of the pulsed voltage signal, it generates a pulsed magnetic field. The winding direction of the excitation coil 5 needs to satisfy that the direction of the electromagnetic field generated by the excitation coil 5 at high levels is consistent with the direction of the static magnetic field generated by the magnet. The winding directions of the first receiving coil 6 and the second receiving coil 7 are the same. When the excitation coil 5 generates changing magnetic fields 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 fields excited by the first eddy current field and the second eddy current field to achieve eddy current detection. When the excitation coil 5 generates an electromagnetic field at high levels, causing the oil and gas pipeline to be in a saturated magnetization state, the magnetic sensor 8 receives the induced magnetic field leaking into the space to achieve magnetic flux leakage detection.

[0057] As Figure 3 shown, the pulsed excitation eddy current and magnetic flux leakage composite detection device for oil and gas pipelines in this embodiment further includes: an integrated electronic system, which includes a pulsed signal generation module, a pre-power amplification module, a low-pass signal conditioning module, a high-pass signal conditioning module, and a data acquisition and storage module.

[0058] The pulsed signal generation module is used to generate a pulsed signal, and the pulsed signal can be a pulsed square wave signal.

[0059] The pre-power amplification module is respectively connected to the pulsed signal generation module and the excitation coil 5. The pre-power amplification module is used to amplify the pulsed signal, provide energy for the pulsed signal, obtain a pulsed voltage signal, and apply the pulsed voltage signal to the excitation coil 5 to drive the excitation coil 5 to generate a pulsed 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 a low-pass conditioned signal.

[0061] The high-pass signal conditioning module is respectively connected to the first receiving coil 6 and the second receiving coil 7. 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 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 respectively connected to the low-pass signal conditioning module and the high-pass signal conditioning module. 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 the traditional eddy current internal detection equipment is seriously affected by the lift-off effect during application, resulting in insufficient accuracy of defect detection, this embodiment designs differential processing, which can improve the detection accuracy.

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

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

[0066] Among them, the high-pass signal conditioning module includes a high-pass filtering unit and a second amplification unit. The high-pass filtering unit is respectively connected to the first receiving coil 6 and the second receiving coil 7. The high-pass filtering unit 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 perform high-pass filtering on the differential signal to obtain the high-pass filtered signal. The second amplification unit is respectively connected to the high-pass filtering unit and the data acquisition and storage module. The second amplification unit is used to amplify the high-pass filtered signal to obtain the high-pass conditioned signal and transmit the high-pass conditioned signal to the data acquisition and storage module.

[0067] The high-pass signal conditioning module of 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 this high-pass signal conditioning module and first undergo differential processing. The obtained original differential signal contains low-frequency electromagnetic noise in space, so it can be filtered out by the high-pass filtering part, and the high-frequency eddy current field signal corresponding to the pipeline defect passes through to realize eddy current detection.

[0068] In this embodiment, the magnet can be parallel to the axis of the oil and gas pipeline. Both the first yoke 3 and the second yoke 4 can 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. 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 pulsed excitation probe can include a housing. After installing 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 in the housing, all components are completely cured using glue such as epoxy resin. 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 are kept unchanged.

[0070] As Figure 4 shown, in this embodiment, during detection, the pulsed excitation eddy current and magnetic flux leakage composite detection device for oil and gas pipelines is placed into the oil and gas pipeline to be measured. The magnet is used to generate a static magnetic field. 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 pulsed excitation probe and the local oil and gas pipeline covered by the magnet, the first yoke 3, and the second yoke 4, making the inner surface of the oil and gas pipeline in a static magnetization state. The magnetic 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] As Figure 5 and Figure 6 shown, the excitation coil 5 is used to be applied with a pulsed voltage signal. The pulsed voltage signal is a curve of the excitation voltage changing with time. The pulsed voltage signal includes a rising edge, a high level, a falling edge, and a low level. When the pulsed voltage signal is at the high level, the excitation coil 5 generates an electromagnetic field. The magnetic field strength of the electromagnetic field is H2, and the direction of the electromagnetic field is the same as the direction 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 vectorially superimposed, and the magnetic field strength of the superimposed magnetic field reaches the saturation magnetization intensity H S, the inner surface of the oil and gas pipeline is saturatedly magnetized 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 the falling edge, that is, when the exciting coil 5 is applied with the exciting voltage at the rising edge and the falling edge, the electromagnetic field generated by the exciting coil 5 will change transiently, that is, a changing magnetic field is 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, a first eddy current field and a second eddy current field are 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, 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 exciting coil 5 does not generate an electromagnetic field.

[0072] The induced magnetic fields excited by the first eddy current field and the second eddy current field will hinder the changing trend of the electromagnetic field. When crack defects and corrosion defects appear on the inner surface of the oil and gas pipeline, the magnetic fluxes in the first receiving coil 6 and the second receiving coil 7 change and corresponding first voltage signal and second voltage signal are output. At this time, the first voltage signal and the second voltage signal 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, 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 voltage signal and the second voltage signal are differentiated, high-pass filtered and amplified by the high-pass signal conditioning module, they are input to the data acquisition and storage module. The crack defects and corrosion defects on the inner surface of the oil and gas pipeline are detected through the obtained high-pass conditioned signals, and eddy current detection is realized.

[0073] When eddy current detection is carried out, since the inner surface of the oil and gas pipeline is in a static magnetization state and the magnetic permeability is reduced to μ1, the eddy current will further penetrate into the inner part of the pipe wall. Therefore, when eddy current detection is implemented, the eddy current field signal carries deeper defect information.

[0074] When there are volumetric defects such as inner surface corrosion and outer surface corrosion, the internal magnetic field on the inner surface of the oil and gas pipeline in a saturated magnetization state leaks into the space and is captured by the magnetic sensor 8 and a corresponding voltage signal is output. At this time, the voltage signal is a 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 output 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 volumetric defects of the oil and gas pipeline and the crack defects with a large included angle with the magnetic force line are detected through the obtained low-pass conditioned signals, and magnetic flux leakage detection is realized.

[0075] Such as Figure 7As shown, it is a schematic diagram of the permeability (μ) and magnetic induction intensity (or magnetic flux density, B) of an oil and gas pipeline changing with the magnetic field intensity (H) during the detection process. When the oil and gas pipeline is in an unmagnetized state, the magnetic field intensity is 0, the magnetic induction intensity is 0, and the permeability is μ0. When the oil and gas pipeline is in a static magnetization state, the magnetic field intensity is H1, the magnetic induction intensity is B1, and the permeability is reduced to μ1. When the pulse voltage signal is at a high level, the magnetic field intensity of the generated electromagnetic field is H2, and the oil and gas pipeline is saturatedly magnetized. The magnetic field intensity received by the oil and gas pipeline is the vector superposition of H1 and H2, which is the saturated magnetization intensity H S , and this is the magnetic flux leakage detection stage, and the magnetic induction intensity is B S , and the permeability is further reduced. 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. This is the eddy current detection stage, the magnetic induction intensity is B1, and the permeability is μ1.

[0076] Among them, the eddy current penetration depth calculation formula is:

[0077]

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

[0079] Obviously, when the permeability decreases, the eddy current penetration depth increases, which proves that the pulsed 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 inner surface crack defects and inner surface corrosion defects, and the defects that can be detected by magnetic flux leakage detection include inner surface corrosion defects and outer surface corrosion defects. It can also detect inner surface crack defects and outer surface crack defects with a large included angle with the magnetic force lines.

[0081] The magnetic flux leakage internal detection equipment can detect volumetric defects such as internal and external corrosion of oil and gas pipelines. However, since the detection probe in the magnetic flux leakage internal detection equipment is separated from the pipe section magnetization device, and the detection probe is located in the middle position of the pipe section magnetization device, the pipe section magnetization device applies saturated magnetization to a section of the pipeline, but the detection probe only extracts the magnetic field information of the area covered by the detection probe. Therefore, the saturated magnetization applied by the pipe section magnetization device to the area not covered by the detection probe is equivalent to doing useless work, resulting in a waste of magnetic field resources. Moreover, in the magnetic flux leakage internal detection equipment, the pipe section magnetization device applies saturated magnetization to some pipe sections, which requires a huge magnet volume, resulting in a huge volume and weight of the magnetic flux leakage internal detection equipment, making it difficult to be applied to low-pressure and low-displacement oil and gas pipelines. At the same time, restricted by the detection mechanism, it is difficult for the magnetic flux leakage internal detection equipment to detect crack defects with a small included angle with the magnetic force lines. The 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 crack defects with a large included angle with the magnetic force lines and crack defects with a small included angle with the magnetic force lines. However, since oil and gas pipelines are generally ferromagnetic materials with a high magnetic permeability, the penetration depth of the eddy current is insufficient, making it difficult to detect deeper defect information on the inner surface of the oil and gas pipelines. To solve this problem, this embodiment combines the advantages of traditional magnetic flux leakage and eddy current detection technologies, and proposes a pulsed excitation eddy current and magnetic flux leakage composite detection device for oil and gas pipelines, integrating the pipe section magnetization device (i.e., the magnet and the excitation coil 5) with the detection probe (i.e., the magnetic sensor 8). The saturated magnetization is applied to the area covered by the detection probe by using the method of superimposing a pulsed excitation (i.e., a pulsed voltage signal) on a static magnetic field, that is, only the area covered by the detection probe is saturated magnetized and the magnetic field information is extracted, avoiding the waste of magnetic field resources. When at the high level of the pulsed excitation, the electromagnetic field of the excitation coil 5 is superimposed on the static magnetic field of the magnet to apply saturated magnetization to the area covered by the detection probe. When there are volumetric defects, the magnetic sensor 8 captures the change in the magnetic leakage field in space to achieve magnetic flux leakage detection. Compared with the method of completely using the static magnetic field generated by the magnet to saturate the magnetization of the inner surface of the oil and gas pipeline, it can reduce the volume and weight, be applicable to low-pressure and low-displacement oil and gas pipelines, and has a wide application range. When at the rising edge and falling edge of the pulsed excitation, the electromagnetic field of the excitation coil 5 generates transient changes, and two eddy current fields in opposite directions are generated on the inner surface of the oil and gas pipeline, which can effectively detect crack and corrosion defects on the inner wall of the pipeline to achieve eddy current detection. At the same time, there is a static magnetic field in the area covered by the probe, the magnetic permeability of the oil and gas pipeline decreases, and the eddy current penetration depth increases, realizing the effective acquisition of deeper defect information on the inner wall of the oil and gas pipeline.

[0082] This embodiment has the following advantages.

[0083] (1) When applying saturated magnetization to the oil and gas pipeline (static magnetic field + electromagnetic field in the high-level stage), saturated magnetization is only applied to the area covered by the probe. Therefore, compared with the method of applying saturated magnetization to the whole of some pipe segments by traditional magnetic flux leakage internal detection equipment, the waste of magnetic field resources is avoided, and the volume and weight are significantly reduced.

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

[0085] (3) The pulsed excitation probe combines the advantages of the two technologies of magnetic flux leakage and eddy current, and can realize the detection of cracks, internal and external corrosion defects in the pipeline and the discrimination of the defect positions, improving the efficiency and accuracy of the internal detection of the pipeline.

[0086] In this embodiment, there are multiple pulsed excitation probes, and the multiple pulsed excitation probes are arranged in an array. There are multiple integrated electronic systems, and one integrated electronic system corresponds to one pulsed excitation probe.

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

[0088] In this embodiment, the detector frame 9 is a circular cylinder, and the 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, the integrated electronic system 12, etc. The probe arm 10 can be made of steel, connecting the pulsed excitation probe 11 and the detector frame 9.

[0090] The pulsed excitation eddy current and magnetic flux leakage composite detection device for oil and gas pipelines proposed in this embodiment combines the advantages of two technologies, magnetic flux leakage and eddy current. The placed magnet forms a magnetic circuit with the first yoke 3, the second yoke 4, and the local pipeline, which can make the probe closely adhere to the pipe wall, reduce the lift-off noise of the probe jitter, and at the same time apply a static magnetic field to reduce the magnetic permeability. In the high-level stage, precise saturation magnetization is implemented on the area covered by the probe, saving magnetic field resources, reducing the volume and weight, and realizing the detection of volumetric defects on the inner and outer walls of oil and gas pipelines. In the rising edge and falling edge stages, eddy current detection is implemented on the area covered by the probe, which can effectively detect volumetric defects and cracks on the inner wall of the pipeline. Since the eddy current detection is a superposition on the static magnetic field, the magnetic permeability of the pipeline is reduced to μ1, increasing the penetration depth of the eddy current, and the magnetic field excited by the eddy current carries deeper defect information. By the way of coil differential reception of the eddy current field signal, the influence of probe lift-off and electromagnetic interference on the eddy current field signal can be avoided, and the defect recognition accuracy can be improved.

[0091] Embodiment 2.

[0092] This embodiment provides a pulsed excitation eddy current and magnetic flux leakage composite detection method for oil and gas pipelines, which works based on the pulsed excitation eddy current and magnetic flux leakage composite detection device described in Embodiment 1. The pulsed excitation eddy current and magnetic flux leakage composite detection method for 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 by using a magnet, a first yoke, and a second yoke.

[0094] (2) Apply a pulsed voltage signal to the excitation coil. When the pulsed voltage signal is at a high level, use the excitation coil to generate an electromagnetic field. The direction of the electromagnetic field is the same as that of the static magnetic field, making the inner surface of the oil and gas pipeline in a saturated magnetization state. When the pulsed voltage signal is at the rising edge and falling edge, use the excitation coil to generate 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 in the inner surface of the oil and gas pipeline.

[0095] (3) Use the first receiving coil to receive the induced magnetic field generated by the first eddy current field and output a first voltage signal, and use the second receiving coil to receive the induced magnetic field generated by the second eddy current field and output a second voltage signal to realize eddy current detection.

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

[0097] The technical features of the above embodiments can be combined arbitrarily. For the sake of brief description, 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, it should be considered as the scope recorded in this specification.

[0098] In this article, specific examples are used to elaborate on the principles and implementation manners of this application. The descriptions of the above embodiments are only used to help understand the method and its core idea of this application. At the same time, for those of ordinary skill in the art, according to the idea of this application, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation to this application.

Claims

1. A pulse excitation eddy current and magnetic flux leakage composite detection device for oil and gas pipelines, characterized in that: The oil and gas pipeline pulse excitation eddy current and leakage magnetic composite detection device 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 first end of the first yoke away from the inner surface of the oil and gas pipeline is fixedly mounted on the first end of the magnet, and the first end of the second yoke away from the inner surface of the oil and gas pipeline is fixedly mounted on 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; The excitation coil is sleeved on the magnet; the excitation coil is used to be applied with a pulse voltage signal, and when the pulse voltage signal is at a high level, the excitation coil is used to generate an electromagnetic field, and the electromagnetic field and the static magnetic field have the same direction, so that the inner surface of the oil and gas pipeline is in a saturated magnetization state, and when the pulse voltage signal is at a rising edge and a falling edge, the excitation coil is used to generate a first eddy current field at a position corresponding to the first yoke on the inner surface of the oil and gas pipeline, and generate a second eddy current field at a position corresponding to the second yoke; The first receiving coil is sleeved on the second end of the first yoke close to the inner surface of the oil and gas pipeline, and the second receiving coil is sleeved on the second end of the second yoke close to 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, and 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 to realize eddy current detection; 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 by the inner surface of the oil and gas pipeline in a saturated magnetization state, output a voltage signal, and realize magnetic leakage detection.

2. The pulse excitation eddy current and magnetic flux leakage composite detection device for oil and gas pipelines according to claim 1 is characterized in that: The oil and gas pipeline pulse excitation eddy current and leakage magnetic composite detection device also includes: an integrated electronic system, which includes a pulse signal generation module, a pre-power amplifier module, a low-pass signal conditioning module, a high-pass signal conditioning module and a data acquisition storage module; The pulse signal generating module is used to stimulate a pulse signal; The pre-power amplifier module is connected to the pulse signal generating module and the excitation coil respectively; the pre-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 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 magnetic flux leakage composite detection device according to claim 2 is characterized in that: The low-pass signal conditioning module includes a low-pass filtering unit and a first amplifying 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 amplifying unit is connected to the low-pass filtering unit and the data acquisition storage module respectively; the first amplifying unit is used to amplify the low-pass filtered signal to obtain a low-pass conditioned signal.

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

5. The pulse excitation eddy current and magnetic flux leakage composite detection device for oil and gas pipelines according to claim 1 is characterized in that: The magnet is parallel to the axis of the oil and gas pipeline, the first yoke and the second yoke are 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 at the same distance from the inner surface of the oil and gas pipeline.

6. The oil and gas pipeline pulse excitation eddy current and magnetic flux leakage composite detection device according to claim 1 is characterized in that: The defects that can be detected by eddy current testing include inner surface crack defects and inner surface corrosion defects, and the defects that can be detected by magnetic flux leakage testing include inner surface corrosion defects and outer surface corrosion defects.

7. The pulse excitation eddy current and magnetic flux leakage composite detection device for oil and gas pipelines according to claim 2 is 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 one integrated electronic system corresponds to one pulse excitation probe.

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

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

10. A pulse excitation eddy current and magnetic flux leakage composite detection method for oil and gas pipelines, based on the pulse excitation eddy current and magnetic flux leakage composite detection device for oil and gas pipelines according to any one of claims 1 to 9, characterized in that: The oil and gas pipeline pulse excitation eddy current and magnetic leakage composite detection method comprises: Applying a static magnetic field to the inner surface of the oil and gas pipeline using a magnet, a first yoke, and a second yoke; Applying a pulse voltage signal to the excitation coil, when the pulse voltage signal is at a high level, using the excitation coil to generate an electromagnetic field, the electromagnetic field and the static magnetic field have the same direction, so that the inner surface of the oil and gas pipeline is in a saturated magnetization state, and when the pulse voltage signal is at a rising edge and a falling edge, using the excitation coil to generate a first eddy current field at a position corresponding to the first yoke on the inner surface of the oil and gas pipeline, and a second eddy current field at a position corresponding to the second yoke; Using a first receiving coil to receive the induced magnetic field generated by the first eddy current field and output a first voltage signal, and using a second receiving coil to receive the induced magnetic field generated by the second eddy current field and output a second voltage signal to achieve eddy current detection; The magnetic sensor 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 output a voltage signal to achieve magnetic leakage detection.

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