Well control device structure defect detection method and probe based on dual-frequency electromagnetic excitation

Abstract

The present application belongs to the technical field of oil and gas equipment detection, and particularly relates to a well control device structure defect detection method and probe based on double-frequency electromagnetic excitation. The structure defect detection method and probe realize the detection and identification of structure defects at different positions of the marine well control device by double-frequency electromagnetic excitation and phase-locked demodulation of reflected electromagnetic detection signals and transmitted electromagnetic detection signals of different frequencies. The well control device structure defect detection probe based on double-frequency electromagnetic excitation comprises a probe shell, a first magnetic field sensor, a second magnetic field sensor, a first excitation coil, a second excitation coil, a first magnetic core and a second magnetic core. The probe shell has a U-shaped structure, and a groove space is arranged between the first leg and the second leg of the U-shaped structure. A first fixed groove is arranged on the first leg of the U-shaped structure, a second fixed groove is arranged on the second leg of the U-shaped structure, and the first fixed groove and the second fixed groove are symmetrically arranged.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas equipment testing technology, and particularly relates to a method and probe for detecting structural defects in well control devices based on dual-frequency electromagnetic excitation. Background Technology

[0002] In well control systems such as offshore drilling platforms and subsea pipelines, critical load-bearing components (e.g., blowout preventer housings, valve components) are subjected to harsh conditions of high pressure and strong corrosion for extended periods, making their surfaces and interiors prone to structural defects. It is noteworthy that these load-bearing components typically have significant thickness or volume, and their integrity directly impacts the overall operational safety of the well control system and the protection of the surrounding environment. Therefore, regularly conducting non-destructive testing on these load-bearing components is crucial.

[0003] Among them, electromagnetic detection technology based on alternating electromagnetic fields, as an emerging non-destructive testing process, has the advantages of being non-contact, resistant to lift-off interference, and having high quantitative accuracy, and is widely used in the detection of structural defects in (metal components) of well control devices. However, further research has revealed that existing alternating electromagnetic field detection technologies have the following significant limitations in application: For example, while the magnetic field sensor captures the detection magnetic field signal, the magnetic field signal also contains the background magnetic field and the distorted magnetic field caused by structural defects, making its detection results and sensitivity susceptible to interference from fluctuations in the background magnetic field; in addition, most conventional detection methods adopt a reflective detection mode, which is not sensitive to changes in the induced current inside the structure, making it difficult to effectively detect internal defects in thick, large-volume components; finally, the magnetic field information obtained by existing detection processes has limited dimensions, making it impossible to achieve comprehensive and accurate localization of structural defects in well control devices. Summary of the Invention

[0004] This invention provides a method and probe for detecting structural defects in well control devices based on dual-frequency electromagnetic excitation. The method and probe utilize dual-frequency electromagnetic excitation and phase-locked demodulation to generate reflective and transmissive electromagnetic detection signals of different frequencies, thereby enabling the detection and identification of structural defects at different locations within the marine well control device, effectively improving detection sensitivity and structural defect identification capabilities.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] The method for detecting structural defects in well control devices based on dual-frequency electromagnetic excitation includes the following steps:

[0007] Step S1: Based on the structural characteristics and testing requirements of the well control device to be tested, determine the dual-frequency electromagnetic excitation signal required for the testing process; wherein, the dual-frequency electromagnetic excitation signal consists of a first electromagnetic excitation signal with excitation frequency f1 and amplitude A1 and a second electromagnetic excitation signal with excitation frequency f2 and amplitude A2;

[0008] Step S2: Generate two sinusoidal drive signals corresponding to the dual-frequency electromagnetic excitation signal;

[0009] Step S3: Apply the two sinusoidal drive signals to the first excitation coil and the second excitation coil respectively to obtain the first alternating magnetic field and the second alternating magnetic field;

[0010] Step S4: Place the well control device to be tested into the total spatial magnetic field formed by the mixture of the first alternating magnetic field and the second alternating magnetic field, and move it at a constant speed along the path to be tested to achieve continuous scanning of the well control device to be tested;

[0011] Step S5: The changes in the total magnetic field in space during the scanning process of the well control device under test are captured by the first magnetic field sensor and the second magnetic field sensor set on different sides of the well control device under test;

[0012] Step S6: After filtering and amplifying the original first magnetic field signal acquired by the first magnetic field sensor and the original second magnetic field signal acquired by the second magnetic field sensor, respectively, they are sent to the dual-frequency lock-in amplifier.

[0013] Step S7: Using a dual-frequency lock-in amplifier, demodulate the real and imaginary parts of the magnetic field signal with frequency f1 and the magnetic field signal with frequency f2 in the original signal of the first magnetic field, and demodulate the real and imaginary parts of the magnetic field signal with frequency f1 and the magnetic field signal with frequency f2 in the original signal of the second magnetic field.

[0014] Step S8: Perform Fourier transform and frequency domain analysis on the magnetic field signals with frequency f1 and frequency f2 in the demodulated first original magnetic field signal and the magnetic field signals with frequency f1 and frequency f2 in the demodulated second original magnetic field signal.

[0015] A first magnetic field signal with a frequency of f1, a first magnetic field signal with a frequency of f2, a second magnetic field signal with a frequency of f1, and a second magnetic field signal with a frequency of f2 are obtained.

[0016] Step S9: Perform signal analysis on the first transmission magnetic field signal with frequency f2 and the second transmission magnetic field signal with frequency f1:

[0017] If no peak signal characteristics appear in either the first transmission magnetic field signal with frequency f2 or the second transmission magnetic field signal with frequency f1, it is determined that there are no structural defects in the well control device to be tested.

[0018] A more preferred option includes the following steps:

[0019] Step S10: If both the first transmission magnetic field signal with frequency f2 and the second transmission magnetic field signal with frequency f1 exhibit peak signal characteristics, then further signal analysis is performed on the first reflection magnetic field signal with frequency f1 and the second reflection magnetic field signal with frequency f2:

[0020] If a trough signal characteristic appears in the first reflective magnetic field signal with frequency f1, and no trough signal characteristic appears in the second reflective magnetic field signal with frequency f2, then it is determined that there is a structural defect in the well control device to be tested on the side near the first magnetic field sensor.

[0021] If a trough signal characteristic appears in the reflected second magnetic field signal with frequency f2, but no trough signal characteristic appears in the reflected first magnetic field signal with frequency f1, then it is determined that there is a structural defect in the well control device under test on the side near the second magnetic field sensor.

[0022] If both the first reflective magnetic field signal with frequency f1 and the second reflective magnetic field signal with frequency f2 exhibit trough signal characteristics, it is determined that there is a structural defect penetrating the interior of the well control device to be tested.

[0023] On the other hand, the well control device structural defect detection probe based on dual-frequency electromagnetic excitation includes: a probe housing, and a first magnetic field sensor, a second magnetic field sensor, a first excitation coil, a second excitation coil, a first magnetic core, and a second magnetic core disposed inside the probe housing;

[0024] The probe housing has a U-shaped structure, and a groove space is provided between the first leg and the second leg of the U-shaped structure for continuous scanning of the well control device to be detected; and a first fixing groove is provided on the first leg of the U-shaped structure, and a second fixing groove is provided on the second leg of the U-shaped structure, with the first fixing groove and the second fixing groove being symmetrically arranged.

[0025] The first magnetic field sensor, the first excitation coil, and the first magnetic core are fixedly installed in the first fixed groove, and the second magnetic field sensor, the second excitation coil, and the second magnetic core are fixedly installed in the second fixed groove.

[0026] A more preferred option also includes: a signal processing circuit board;

[0027] The signal processing circuit board is fixed by a circuit board mounting post set on the inner wall of the probe housing.

[0028] Preferred options also include: Remer connectors;

[0029] The Remer connector is installed at the opening of the probe housing and is used to establish data connection relationships between the first magnetic field sensor, the first excitation coil, the second magnetic field sensor, the second excitation coil, and the signal processing circuit board.

[0030] Preferably, a probe housing is also fitted with a probe encapsulation cover.

[0031] This invention provides a method and probe for detecting structural defects in well control devices based on dual-frequency electromagnetic excitation. Specifically, the probe includes a probe housing and a first magnetic field sensor, a second magnetic field sensor, a first excitation coil, a second excitation coil, a first magnetic core, and a second magnetic core disposed within the probe housing. The probe housing has a U-shaped structure, with a groove between the first and second legs of the U-shaped structure for continuously scanning the passage of the well control device to be tested. A first fixing groove is provided on the first leg of the U-shaped structure, and a second fixing groove is provided on the second leg of the U-shaped structure; the first and second fixing grooves are symmetrically arranged. The first magnetic field sensor, the first excitation coil, and the first magnetic core are fixedly installed in the first fixing groove, and the second magnetic field sensor, the second excitation coil, and the second magnetic core are fixedly installed in the second fixing groove.

[0032] The present invention, which possesses the above-described step features and structural features, provides a method and probe for detecting structural defects in well control devices based on dual-frequency electromagnetic excitation. Compared with the prior art, it has at least the following technical advantages:

[0033] This invention provides a method and probe for detecting structural defects in well control devices based on dual-frequency electromagnetic excitation. Specifically, by setting a dual-excitation and dual-receiver structure in the structural defect detection probe, an independent dual-frequency electromagnetic field is induced during the defect detection process of the well control device under test. Furthermore, through dual-frequency phase-locked amplification processing, reflected magnetic field signals and transmitted magnetic field signals of different frequencies are obtained, thereby realizing the detection of structural defects at different locations of the well control device. Ultimately, it achieves high-sensitivity detection and defect location identification of structural defects in well control devices, providing technical support for solving the problem of difficult identification of internal defects in offshore oil well control devices. Attached Figure Description

[0034] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the following drawings:

[0035] Figure 1 A schematic diagram of the structure of the well control device structural defect detection probe based on dual-frequency electromagnetic excitation provided by the present invention;

[0036] Figure 2 This is a schematic diagram of the probe housing structure;

[0037] Figure 3 This is a flowchart illustrating the method for detecting structural defects in well control devices based on dual-frequency electromagnetic excitation provided by the present invention.

[0038] Figure 4 This is a schematic diagram of the propagation path of the primary excitation magnetic field in the first and second alternating magnetic fields;

[0039] Figure 5 for Figure 4 The diagram shows the energy decay of a primary excitation magnetic field.

[0040] Figure 6 A schematic diagram illustrating the detection results of defects at different locations in an offshore oil well control device using the dual-frequency electromagnetic excitation-based well control device structural defect detection method provided by this invention.

[0041] Figure 7 This is a schematic diagram showing the detection results of defects at different locations of offshore oil well control devices using the existing reflective AC electromagnetic field detection method.

[0042] Figure 8 This is a schematic diagram showing the detection results of defects at different locations in offshore oil well control devices using a single-frequency transmission electromagnetic detection method in the existing technology.

[0043] Figure label:

[0044] 10. Probe housing; 101. First fixing groove; 102. Opening; 103. Circuit board mounting post; 20. Magnetic field sensor group; 201. First magnetic field sensor; 202. Second magnetic field sensor; 30. Excitation coil group; 301. First excitation coil; 302. Second excitation coil; 40. Magnetic core group; 401. First magnetic core; 402. Second magnetic core; 50. Remer connector; 60. Signal processing circuit board; 70. Probe encapsulation cover. Detailed Implementation

[0045] This invention provides a method and probe for detecting structural defects in well control devices based on dual-frequency electromagnetic excitation. The method and probe utilize dual-frequency electromagnetic excitation and phase-locked demodulation to generate reflective and transmissive electromagnetic detection signals of different frequencies, thereby enabling the detection and identification of structural defects at different locations within the marine well control device, effectively improving detection sensitivity and structural defect identification capabilities.

[0046] Here, we first describe the structural defect detection probe for well control devices based on dual-frequency electromagnetic excitation provided by the present invention as follows. Figure 1As shown, the well control device structural defect detection probe includes: a probe housing 10, and a first magnetic field sensor 201, a second magnetic field sensor 202, a first excitation coil 301, a second excitation coil 302, a first magnetic core 401, and a second magnetic core 402 disposed inside the probe housing 10.

[0047] It is worth noting that the probe housing 10 has a U-shaped structure, and a groove space is provided between the first and second legs of the U-shaped structure for continuous scanning of the well control device to be detected. In addition, a first fixing groove is provided on the first leg of the U-shaped structure, and a second fixing groove is provided on the second leg of the U-shaped structure. The first fixing groove and the second fixing groove are symmetrically arranged.

[0048] The first magnetic field sensor 201, the first excitation coil 301, and the first magnetic core 401 are fixedly installed in the first fixing groove 101. Specifically, the first excitation coil 301 is wound around the first magnetic core 401 to receive a sinusoidal drive signal and generate a first alternating magnetic field with an excitation frequency f1 and an amplitude A1. The second magnetic field sensor 202, the second excitation coil 302, and the second magnetic core 402 are fixedly installed in the second fixing groove; the second excitation coil 302 is wound around the second magnetic core 402 to receive a sinusoidal drive signal and generate a second alternating magnetic field with an excitation frequency f2 and an amplitude A2.

[0049] To facilitate understanding by those skilled in the art, the working process of the well control device structural defect detection probe based on dual-frequency electromagnetic excitation provided by the present invention is further explained as follows: First, two sinusoidal drive signals corresponding to the first alternating magnetic field with excitation frequency f1 and amplitude A1, and the second alternating magnetic field with excitation frequency f2 and amplitude A2 are determined; then, the drive signals are amplified by a power amplifier and loaded into the first excitation coil 301 and the second excitation coil 302 respectively, thereby inducing the first alternating magnetic field and the second alternating magnetic field of different frequencies.

[0050] Then, the well control device to be tested is placed in the total spatial magnetic field (which is formed by a mixture of a first alternating magnetic field and a second alternating magnetic field). Due to the electromagnetic shielding effect, the background magnetic field generated by the first excitation coil 301 and the second excitation coil 302 is significantly shielded by the well control device to be tested. The first magnetic field sensor 201 and the second magnetic field sensor 202 can then be used to further extract the secondary magnetic field generated by the induced current inside the well control device. This secondary magnetic field directly originates from the distribution of the induced current inside the well control device. Therefore, when there are structural defects inside the well control device (such as cracks or corrosion), the flow path of the induced current inside will change, and the resulting secondary magnetic field will also be distorted. It should be noted that, since the defect detection probe of this structure has a dual-excitation and dual-receiver structure, the magnetic field sensor group 20 (composed of the first magnetic field sensor 201 and the second magnetic field sensor 202), the excitation coil group 30 (composed of the first excitation coil 301 and the second excitation coil 302), and the magnetic core group 40 (composed of the first magnetic core 401 and the second magnetic core 402) are preferably symmetrically distributed. In this case, the magnetic field changes induced inside the well control device under test by the first and second alternating magnetic fields, after being acquired by the magnetic field sensor group 20, can be demodulated using a dual-frequency lock-in amplifier to obtain reflected and transmitted magnetic field signals of different frequencies, thereby obtaining richer defect signal characteristics compared to existing technologies.

[0051] As a preferred embodiment of the present invention, such as Figure 1 As shown, the well control device structural defect detection probe based on dual-frequency electromagnetic excitation also includes a Remer connector 50 and a signal processing circuit board 60. The Remer connector 50 is installed at the opening 102 of the probe housing, used to establish data connections between the first magnetic field sensor, the first excitation coil, the second magnetic field sensor, the second excitation coil, and the signal processing circuit board. The signal processing circuit board 60 is fixed by circuit board mounting posts 103 on the inner wall of the probe housing, as detailed in the example below. Figure 2 As shown. Additionally, a probe encapsulation cover 70 is installed around the probe housing 10. This probe encapsulation cover 70 is used to seal and protect the various circuit components inside the probe housing 10, which will not be described in detail here.

[0052] On the other hand, the present invention also provides a method for detecting structural defects in well control devices based on dual-frequency electromagnetic excitation, such as... Figure 3 As shown, it includes the following steps:

[0053] Step S1: Based on the structural characteristics and testing requirements of the well control device to be tested, determine the dual-frequency electromagnetic excitation signal required for the testing process; wherein, the dual-frequency electromagnetic excitation signal consists of a first electromagnetic excitation signal with excitation frequency f1 and amplitude A1 and a second electromagnetic excitation signal with excitation frequency f2 and amplitude A2.

[0054] Specifically, the first and second electromagnetic excitation signals in the dual-frequency electromagnetic excitation signals are determined by the structural characteristics of the well control device to be tested and the testing requirements. Preferably, the excitation frequency f1 of the first electromagnetic excitation signal is 5kHz and the amplitude A1 is 5V, and the excitation frequency f2 of the second electromagnetic excitation signal is 8kHz and the amplitude A2 is 5V.

[0055] Step S2: Generate two sinusoidal drive signals corresponding to the dual-frequency electromagnetic excitation signal.

[0056] Step S3: Apply the two sinusoidal drive signals to the first excitation coil and the second excitation coil respectively to obtain the first alternating magnetic field and the second alternating magnetic field.

[0057] Based on completing steps S1 and S2, step S3 is further implemented. Specifically, after obtaining the two sinusoidal drive signals corresponding to the dual-frequency electromagnetic excitation signals, the first electromagnetic excitation signal with an excitation frequency f1 of 5kHz is applied to the first excitation coil to obtain the first alternating magnetic field; and the second electromagnetic excitation signal with an excitation frequency f2 of 8kHz is selected to be applied to the second excitation coil to obtain the second alternating magnetic field.

[0058] It should be noted that the excitation magnetic field signals emitted by the first and second excitation coils further include a primary excitation magnetic field generated by the excitation and a secondary induced magnetic field generated by the induced current of the well control device under test. The primary and secondary induced magnetic fields, when mixed, constitute the first and second alternating magnetic fields. Specifically, before entering the well control device under test, part of the primary excitation magnetic field is reflected into the air, while the remaining magnetic field entering the device undergoes multiple reflections within it. Therefore, the propagation path of the primary excitation magnetic field contained in the first and second alternating magnetic fields can be specifically referred to as follows: Figure 4 As shown.

[0059] In addition, when the primary excitation magnetic field enters the surface of the well control device under test, some of the magnetic field is reflected into the air, resulting in an initial decrease in magnetic energy. After entering the device, it undergoes multiple reflections, leading to an exponential decrease in magnetic energy. Finally, the energy decreases further when refracted out of the surface. Therefore, the energy of the primary excitation magnetic field is significantly reduced after passing through the device, and the energy attenuation process is as follows: Figure 5As shown. For sensors, the vast majority of the magnetic field information they capture comes from the secondary induced magnetic field generated by the induced current.

[0060] Step S4: Place the well control device to be tested into the total spatial magnetic field formed by the mixture of the first alternating magnetic field and the second alternating magnetic field, and move it at a constant speed along the path to be tested to achieve continuous scanning of the well control device to be tested.

[0061] Step S5: The changes in the total magnetic field in space during the scanning process of the well control device under test are captured by the first magnetic field sensor and the second magnetic field sensor set on different sides of the well control device under test.

[0062] Step S6: After filtering and amplifying the original first magnetic field signal acquired by the first magnetic field sensor and the original second magnetic field signal acquired by the second magnetic field sensor, respectively, they are sent to the dual-frequency lock-in amplifier.

[0063] Step S7: Using a dual-frequency lock-in amplifier, demodulate the real and imaginary parts of the magnetic field signal with frequency f1 and the magnetic field signal with frequency f2 in the original signal of the first magnetic field, and demodulate the real and imaginary parts of the magnetic field signal with frequency f1 and the magnetic field signal with frequency f2 in the original signal of the second magnetic field.

[0064] Based on completing steps S4-S6, step S7 is further implemented. It is worth noting that during the continuous scanning of the well control device to be inspected, the total magnetic field in space will change due to the structural defects of the well control device. Then, after the first magnetic field sensor collects the first original magnetic field signal and the second magnetic field sensor collects the second original magnetic field signal, after filtering and amplification, the signals are sent to a dual-frequency lock-in amplifier to demodulate the specific signal characteristics of the magnetic field signals of different frequencies in the first and second original magnetic field signals (for example, demodulating the real and imaginary parts of the 5kHz magnetic field signal with frequency f1 and the 8kHz magnetic field signal with frequency f2 in the first original magnetic field signal, and demodulating the real and imaginary parts of the 5kHz magnetic field signal with frequency f1 and the 8kHz magnetic field signal with frequency f2 in the second original magnetic field signal).

[0065] Step S8: Perform Fourier transform and frequency domain analysis on the magnetic field signals with frequency f1 and frequency f2 in the demodulated first original magnetic field signal and the magnetic field signals with frequency f1 and frequency f2 in the demodulated second original magnetic field signal.

[0066] A first reflective magnetic field signal with frequency f1, a first transmittance magnetic field signal with frequency f2, a second transmittance magnetic field signal with frequency f1, and a second reflective magnetic field signal with frequency f2 are obtained.

[0067] Step S9: Perform signal analysis on the first transmission magnetic field signal with frequency f2 and the second transmission magnetic field signal with frequency f1: If no peak signal characteristics appear in either the first transmission magnetic field signal with frequency f2 or the second transmission magnetic field signal with frequency f1, it is determined that there are no structural defects in the well control device to be tested.

[0068] If both the first transmissive magnetic field signal with frequency f2 and the second transmissive magnetic field signal with frequency f1 exhibit peak signal characteristics, then further signal analysis should be performed on the first reflective magnetic field signal with frequency f1 and the second reflective magnetic field signal with frequency f2:

[0069] If a trough signal characteristic appears in the first reflective magnetic field signal with frequency f1, and no trough signal characteristic appears in the second reflective magnetic field signal with frequency f2, then it is determined that there is a structural defect in the well control device to be tested on the side near the first magnetic field sensor.

[0070] If a trough signal characteristic appears in the reflected second magnetic field signal with frequency f2, but no trough signal characteristic appears in the reflected first magnetic field signal with frequency f1, then it is determined that there is a structural defect in the well control device under test on the side near the second magnetic field sensor.

[0071] If both the first reflective magnetic field signal with frequency f1 and the second reflective magnetic field signal with frequency f2 exhibit trough signal characteristics, it is determined that there is a structural defect penetrating the interior of the well control device to be tested.

[0072] Based on the completion of step S7, further implement steps S8 and S9. It is worth noting that, as shown in the following example... Figure 6 As shown, based on the different signal characteristics appearing in the four electromagnetic (detection) signals above, the defect location information of the offshore oil well control device to be inspected can be clearly determined. During the inspection process, a single scan can achieve high-sensitivity detection and location identification of defects on the thick surface, interior, and lower surface of the offshore oil well control device.

[0073] To verify the effectiveness of the well control device structural defect detection method provided by this invention, the following example is further provided: Wherein, Figure 7 This diagram illustrates the detection results of existing reflective AC electromagnetic field detection methods for defects at different locations in offshore oil well control equipment. Figure 8This diagram illustrates the detection results of single-frequency transmission electromagnetic detection methods for defects at different locations in offshore oil well control devices. It can be seen that the well control device structural defect detection method provided by this invention is more sensitive to detecting internal defects in the thick structures of offshore oil well control devices, achieving the identification of defect locations in the depth direction of the well control device under test. This solves the problem of difficulty in identifying internal defects in the thick structures of offshore oil well control devices, and its defect detection results are significantly improved compared to existing technologies.

[0074] This invention provides a method and probe for detecting structural defects in well control devices based on dual-frequency electromagnetic excitation. Specifically, the probe includes a probe housing and a first magnetic field sensor, a second magnetic field sensor, a first excitation coil, a second excitation coil, a first magnetic core, and a second magnetic core disposed within the probe housing. The probe housing has a U-shaped structure, with a groove between the first and second legs of the U-shaped structure for continuously scanning the passage of the well control device to be tested. A first fixing groove is provided on the first leg of the U-shaped structure, and a second fixing groove is provided on the second leg of the U-shaped structure; the first and second fixing grooves are symmetrically arranged. The first magnetic field sensor, the first excitation coil, and the first magnetic core are fixedly installed in the first fixing groove, and the second magnetic field sensor, the second excitation coil, and the second magnetic core are fixedly installed in the second fixing groove.

[0075] The present invention, which possesses the above-described step features and structural features, provides a method and probe for detecting structural defects in well control devices based on dual-frequency electromagnetic excitation. Compared with the prior art, it has at least the following technical advantages:

[0076] This invention provides a method and probe for detecting structural defects in well control devices based on dual-frequency electromagnetic excitation. Specifically, by setting a dual-excitation and dual-receiver structure in the structural defect detection probe, an independent dual-frequency electromagnetic field is induced during the defect detection process of the well control device under test. Furthermore, through dual-frequency phase-locked amplification processing, reflected magnetic field signals and transmitted magnetic field signals of different frequencies are obtained, thereby realizing the detection of structural defects at different locations of the well control device. Ultimately, it achieves high-sensitivity detection and defect location identification of structural defects in well control devices, providing technical support for solving the problem of difficult identification of internal defects in offshore oil well control devices.

[0077] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for detecting structural defects in well control devices based on dual-frequency electromagnetic excitation, characterized in that, The steps include the following: Step S1: Based on the structural characteristics and testing requirements of the well control device to be tested, determine the dual-frequency electromagnetic excitation signal required for the testing process; wherein, the dual-frequency electromagnetic excitation signal consists of a first electromagnetic excitation signal with excitation frequency f1 and amplitude A1 and a second electromagnetic excitation signal with excitation frequency f2 and amplitude A2; Step S2: Generate two sinusoidal drive signals corresponding to the dual-frequency electromagnetic excitation signal; Step S3: Apply the two sinusoidal drive signals to the first excitation coil and the second excitation coil respectively to obtain the first alternating magnetic field and the second alternating magnetic field; Step S4: Place the well control device to be tested into the total spatial magnetic field formed by the mixture of the first alternating magnetic field and the second alternating magnetic field, and move it at a constant speed along the path to be tested to achieve continuous scanning of the well control device to be tested; Step S5: The changes in the total magnetic field in space during the scanning process of the well control device under test are captured by the first magnetic field sensor and the second magnetic field sensor set on different sides of the well control device under test; Step S6: After filtering and amplifying the original first magnetic field signal acquired by the first magnetic field sensor and the original second magnetic field signal acquired by the second magnetic field sensor, respectively, they are sent to the dual-frequency lock-in amplifier. Step S7: Using a dual-frequency lock-in amplifier, demodulate the real and imaginary parts of the magnetic field signal with frequency f1 and the magnetic field signal with frequency f2 in the original signal of the first magnetic field, and demodulate the real and imaginary parts of the magnetic field signal with frequency f1 and the magnetic field signal with frequency f2 in the original signal of the second magnetic field. Step S8: Perform Fourier transform and frequency domain analysis on the magnetic field signals with frequency f1 and frequency f2 in the demodulated first original magnetic field signal and the magnetic field signals with frequency f1 and frequency f2 in the demodulated second original magnetic field signal. A first magnetic field signal with a frequency of f1, a first magnetic field signal with a frequency of f2, a second magnetic field signal with a frequency of f1, and a second magnetic field signal with a frequency of f2 are obtained. Step S9: Perform signal analysis on the first transmission magnetic field signal with frequency f2 and the second transmission magnetic field signal with frequency f1: If no peak signal characteristics appear in either the first transmission magnetic field signal with frequency f2 or the second transmission magnetic field signal with frequency f1, it is determined that there are no structural defects in the well control device to be tested.

2. The method for detecting structural defects in well control devices based on dual-frequency electromagnetic excitation according to claim 1, characterized in that, It also includes the following steps: Step S10: If both the first transmission magnetic field signal with frequency f2 and the second transmission magnetic field signal with frequency f1 exhibit peak signal characteristics, then further signal analysis is performed on the first reflection magnetic field signal with frequency f1 and the second reflection magnetic field signal with frequency f2: If a trough signal characteristic appears in the first reflective magnetic field signal with frequency f1, and no trough signal characteristic appears in the second reflective magnetic field signal with frequency f2, then it is determined that there is a structural defect in the well control device to be tested on the side near the first magnetic field sensor. If a trough signal characteristic appears in the reflected second magnetic field signal with frequency f2, but no trough signal characteristic appears in the reflected first magnetic field signal with frequency f1, then it is determined that there is a structural defect in the well control device under test on the side near the second magnetic field sensor. If both the first reflective magnetic field signal with frequency f1 and the second reflective magnetic field signal with frequency f2 exhibit trough signal characteristics, it is determined that there is a structural defect penetrating the interior of the well control device to be tested.

3. A well control device structural defect detection probe based on dual-frequency electromagnetic excitation, wherein the well control device structural defect detection probe based on dual-frequency electromagnetic excitation is used to implement the well control device structural defect detection method based on dual-frequency electromagnetic excitation as described in any one of claims 1-2, characterized in that, It includes: a probe housing, and a first magnetic field sensor, a second magnetic field sensor, a first excitation coil, a second excitation coil, a first magnetic core, and a second magnetic core disposed inside the probe housing; The probe housing has a U-shaped structure, and a groove space is provided between the first leg and the second leg of the U-shaped structure for continuous scanning of the well control device to be detected; and a first fixing groove is provided on the first leg of the U-shaped structure, and a second fixing groove is provided on the second leg of the U-shaped structure, with the first fixing groove and the second fixing groove being symmetrically arranged. The first magnetic field sensor, the first excitation coil, and the first magnetic core are fixedly installed in the first fixed groove, and the second magnetic field sensor, the second excitation coil, and the second magnetic core are fixedly installed in the second fixed groove.

4. The well control device structural defect detection probe based on dual-frequency electromagnetic excitation according to claim 3, characterized in that, It also includes: signal processing circuit boards; The signal processing circuit board is fixed by a circuit board mounting post set on the inner wall of the probe housing.

5. The well control device structural defect detection probe based on dual-frequency electromagnetic excitation according to claim 3, characterized in that, It also includes: Remer connector; The Remer connector is installed at the opening of the probe housing and is used to establish data connection relationships between the first magnetic field sensor, the first excitation coil, the second magnetic field sensor, the second excitation coil, and the signal processing circuit board.

6. The well control device structural defect detection probe based on dual-frequency electromagnetic excitation according to claim 3, characterized in that, The probe housing is also fitted with a probe encapsulation cover.

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