External annular and vertical combined nondestructive testing device and method for hydrogen storage well

Abstract

The invention discloses a hydrogen storage well outside annular and vertical combined nondestructive testing device and a testing method. The hydrogen storage well outside annular and vertical combined nondestructive testing device comprises a tubular outer wall retaining wall which is arranged outside a shaft located underground and extends in the length direction of the shaft; an out-well detection space is formed between the outer wall retaining wall and the shaft; in the detection space outside the well, the defect and damage of the shaft are detected by adopting a nondestructive detection technology, and remote operation and data transmission are realized by combining a digital means. During detection, 1, the annular detection space is filled with water through the centrifugal pump and the pipeline; 2, the ultrasonic probe is controlled by the magnetic control annular adjusting device to rotate clockwise and annularly along the shaft; 3, after focusing and scanning are completed by clockwise and annularly rotating for a circle, the ultrasonic probe is moved downwards, and then focusing and scanning are completed by anticlockwise rotating for a circle; and 4, repeating the steps 2 and 3 until the whole surface area of the shaft is focused and scanned. According to the invention, installation and maintenance of detection equipment can be more convenient, and timeliness, reliability and stability of hydrogen storage well detection are improved.

Description

Technical Field

[0001] The invention relates to the technical field of hydrogen storage well detection, and in particular to a combined circumferential and vertical nondestructive detection device and a detection method for a hydrogen storage well. Background Art

[0002] A gas storage well is a well-type tubular facility buried vertically underground for storing compressed gas. It is a high-pressure container in the category of fixed pressure vessels. It has the characteristics of high safety, good corrosion resistance, high land utilization efficiency and significant cost-effectiveness. It has broad application prospects in CNG filling stations and other fields.

[0003] In recent years, with the global emphasis on clean energy and the rapid development of the hydrogen energy industry, underground hydrogen storage wells, as a new hydrogen storage method, have been initially applied and promoted in China. For example, the Banshan Ring Road Comprehensive Refueling Station built by Sinopec in Chongqing is the first hydrogen refueling station in China to use hydrogen storage well technology. The station has a daily hydrogen supply capacity of 1,000 kilograms and mainly provides hydrogen refueling services for Chongqing's first batch of hydrogen energy demonstration buses and urban logistics vehicles. The project not only demonstrates the feasibility of underground hydrogen storage well technology, but also provides a demonstration effect for the subsequent construction and transformation of hydrogen refueling stations. As one of the important ways to store hydrogen energy, underground hydrogen storage wells are expected to be more widely used in the future.

[0004] As a fuel with high energy density, hydrogen is flammable and explosive. Once it leaks into the air and encounters a fire source or high temperature, it may cause serious safety accidents such as fire and explosion. As a key facility for storing hydrogen, the integrity of hydrogen storage wells is of vital importance. During long-term use, hydrogen storage wells may be affected by factors such as the environment and stress, resulting in a decrease in structural performance. At the same time, hydrogen has strong hydrogen embrittlement, mainly because hydrogen is free on the metal surface of the hydrogen storage well to form active hydrogen atoms and penetrate into the metal. The hydrogen atoms that enter the steel combine into hydrogen molecules inside the metal. When hydrogen molecules gather at stress concentration sites (such as metal defects, cracks, etc.), the stress concentration phenomenon will be further aggravated.

[0005] The hydrogen molecule pressure at the stress concentration point and the residual stress inside the material form a combined force. When this combined force exceeds the yield strength of the metal material, it will lead to the formation of cracks. These cracks will continue to expand under the action of stress. When the cracks expand to a certain extent, they will cause partial or overall failure of the hydrogen storage well.

[0006] Therefore, regular or irregular inspections of high-pressure underground hydrogen storage wells and timely detection and treatment of potential problems are crucial to ensure the safe operation of hydrogen storage wells. Nondestructive testing can monitor the structural health of hydrogen storage wells, and timely detect and treat potential defects in hydrogen storage wells, such as cracks and corrosion, to prevent hydrogen leakage and ensure hydrogen storage safety.

[0007] Traditional non-destructive testing of hydrogen storage wells requires entering the well to perform operations. In-well testing is limited by space and testing equipment, and may not be able to quickly and comprehensively cover all areas that need to be tested, thus affecting testing efficiency.

[0008] At the same time, in order to prevent leakage or accidents of high-concentration hydrogen, which may pose a threat to the life safety of inspection personnel, the hydrogen in the well needs to be released before inspection, and the inspection work can only be carried out when the residual concentration of hydrogen in the well is within a safe range. This not only increases the complexity and difficulty of the operation, but also makes it difficult to realize inspection operations at any time.

[0009] Therefore, how to more conveniently evaluate the integrity, reliability and performance status of hydrogen storage wells, timely discover possible defects in hydrogen storage wells, improve the reliability and stability of detection, and at the same time reduce the operational difficulty of detection, greatly saving time and labor costs has become a technical problem that technical personnel in this field urgently need to solve. Summary of the invention

[0010] In view of the above-mentioned defects of the prior art, the present invention provides a combined annular and vertical non-destructive testing device and a testing method for a hydrogen storage well, the purpose of which is to more conveniently evaluate the integrity, reliability and performance status of the hydrogen storage well, timely discover possible defects in the hydrogen storage well, improve the reliability and stability of the detection, and at the same time reduce the operational difficulty of the detection, greatly saving time and labor costs.

[0011] To achieve the above-mentioned purpose, the present invention discloses a combined circumferential and vertical nondestructive testing device outside a hydrogen storage well, comprising a tubular outer wall retaining wall arranged outside a wellbore located underground and extending along the length direction of the wellbore;

[0012] An out-of-well detection space is formed between the outer wall retaining wall and the wellbore;

[0013] Nondestructive testing technology is used in the off-hole detection space to detect defects and damages of the wellbore, and digital means are combined to achieve remote operation and data transmission.

[0014] Preferably, the non-destructive testing technology is ultrasonic non-destructive testing.

[0015] More preferably, the ultrasonic nondestructive testing includes an ultrasonic probe and an adjusting device for adjusting the position of the ultrasonic probe in the detection space outside the well;

[0016] The adjusting device comprises a circumferential track, a circumferential sliding bracket, a extending device and a circumferential magnetic control device;

[0017] The annular track is arranged on the ground outside the opening of the upper end of the wellbore, is coaxially arranged with the wellbore, and is connected to the annular sliding bracket in a movable pair;

[0018] A plurality of pulleys are arranged between the annular sliding bracket and the annular track to form the moving pair, and the extending device and the annular magnetic control device are arranged through a fixed bracket;

[0019] The extending device suspends the ultrasonic probe via a self-controlled cable to achieve vertical reciprocating movement of the ultrasonic probe relative to the magnetically controlled vertical adjustment device;

[0020] The circumferential magnetic control device controls the circumferential sliding bracket to move along the circumferential track;

[0021] The other end of the self-controlled cable is coiled on a cable shaft located outside the wellbore, and the length of the portion entering the wellbore is collected by a rotation sensor.

[0022] More preferably, the ultrasonic probe is provided with a CCTV device;

[0023] A numerical control display screen is provided outside the wellbore for displaying the working status of the regulating device and the collection results of the ultrasonic probe.

[0024] More preferably, the ultrasonic nondestructive testing adopts phased array ultrasonic testing technology, and the coupling method is liquid immersion method.

[0025] More preferably, the water immersion thickness h of the immersion method, that is, the method for selecting the coupling layer is as follows:

[0026] Step 1: Calculate the water immersion thickness h. The specific formula is as follows:

[0027]

[0028] Where D is the diameter of the probe wafer, in mm; a is the ultrasonic wavelength, in mm; V 水 V is the speed of sound of longitudinal waves in water, unit: 1483 m / s; 井 is the speed of sound in the well wall, in m / s; L is the thickness of the well wall in the detection direction, in mm;

[0029] Step 2: Based on the water immersion thickness, through detection tests of different water layer thicknesses, analyze the echo conditions under different water layer thicknesses to obtain the optimal water layer thickness selection range.

[0030] Preferably, the bottom hole seal at the bottom of the wellbore is sealed with the wellbore without leakage; the bottom hole seal and the outer wall retaining wall are sealed with oil well cement;

[0031] A cementing device is provided at the wellhead position at the upper end of the wellbore;

[0032] The cementing device comprises a horizontal plate and supports arranged on both sides of the horizontal plate for fixing the horizontal plate;

[0033] The horizontal plate is provided with a hole matching the wellhead near the middle position, and the wellhead is reinforced by being sleeved on the outside of the wellhead through the hole.

[0034] Preferably, the well cementing clamp device is formed by using reinforced concrete material outside the wellbore.

[0035] The present invention also provides a detection method, using the above-mentioned hydrogen storage well outer annular and vertical combined non-destructive detection device to detect the wellbore, and the specific steps are as follows:

[0036] Step 1: Fill the annular detection space with water through a centrifugal pump and a pipeline;

[0037] Step 2, using numerical control technology to compile a program-designed detection path, control the ultrasonic probe to start from a position flush with the wellhead of the wellbore, control the ultrasonic probe to rotate clockwise along the wellbore through a magnetic control circumferential adjustment device, stimulate the piezoelectric chip to generate ultrasonic waves through an electrical signal, and control the excitation time of each chip to achieve focusing and scanning of the ultrasonic beam;

[0038] Step 3: After rotating one circle clockwise to complete focusing and scanning, the ultrasonic probe is moved downward for a certain distance through the automatic control cable of the ultrasonic probe, and then rotated one circle counterclockwise to complete focusing and scanning;

[0039] Step 4: Repeat steps 2 and 3 until the entire surface area of ​​the wellbore is focused and scanned.

[0040] Preferably, the movement rate of the ultrasonic probe is uniform, and the movement distance between each focusing and scanning, and the distance of each downward movement are smaller than the scanning width of the ultrasonic probe, so that there is at least 15% overlap between the sampling results obtained by every two adjacent focusing and scanning.

[0041] Beneficial effects of the present invention:

[0042] The present invention sets up an annular detection space outside the underground hydrogen storage well, which provides a stable detection environment for ultrasonic detection. This design not only facilitates the installation and maintenance of the detection equipment, improves the timeliness, reliability and stability of the detection, but also reduces the operational difficulty of the detection, greatly saving time and labor costs.

[0043] The concept, specific structure and technical effects of the present invention will be further described below in conjunction with the accompanying drawings to fully understand the purpose, characteristics and effects of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 A schematic diagram of the longitudinal cross-sectional structure of an embodiment of the present invention is shown.

[0045] Figure 2 A schematic diagram of the structure of an adjusting device in one embodiment of the present invention is shown.

[0046] Figure 3 A schematic structural diagram of a cementing device in one embodiment of the present invention is shown.

[0047] Among them, 1. CNC display screen; 2. Cable shaft; 3. Speed ​​sensor; 4. Annular track; 5. Wellbore; 6. Outer wall retaining wall; 7. Ultrasonic probe; 8. Bottom hole head; 9. Oil well cement; 10. Drainage / injection pipe; 11. Pulley; 12. Annular sliding bracket; 13. Centrifugal pump; 14. Cementing device; 15. Automatic cable; 16. Wellhead; 17. Extension device; 18. Annular magnetic control device. DETAILED DESCRIPTION

[0048] Example

[0049] like Figures 1 to 3 As shown, the annular and vertical combined nondestructive testing device outside the hydrogen storage well includes a tubular outer wall retaining wall 6 arranged outside the wellbore 5 located underground and extending along the length direction of the wellbore 5;

[0050] An out-of-well detection space is formed between the outer wall retaining wall 6 and the wellbore 5;

[0051] Nondestructive testing technology is used in the off-hole testing space to detect defects and damages in the wellbore 5, and digital means are combined to achieve remote operation and data transmission.

[0052] In the present invention, a tubular outer wall retaining wall 6 is constructed outside the wellbore 5 of the hydrogen storage well. The tubular outer wall retaining wall 6 has certain rigidity, strength, stability and waterproof performance.

[0053] An off-well detection space is formed between the outer wall retaining wall 6 and the wellbore 5, which can not only prevent the wellbore 5 of the hydrogen storage well from being squeezed by direct contact with the surrounding soil and groundwater, as well as corrosion caused by the surrounding soil, microorganisms, salt water, etc., thereby reducing the impact of the surrounding environment, but also utilize the annular off-well detection space to carry out non-destructive testing outside the wellbore 5 at any time, avoiding direct contact with the high-pressure, high-concentration hydrogen environment inside the hydrogen storage well, thereby reducing the safety risks of testing and the difficulty of operation.

[0054] Nondestructive testing technologies, such as ultrasonic testing and X-ray testing, are used in the off-hole testing space to quickly and accurately detect defects and damages in the wellbore 5 without destroying the structure of the hydrogen storage well. Digital means can also be used to achieve remote operation and data transmission, which helps to take timely measures for repair and maintenance, further improving the detection efficiency.

[0055] The annular off-well detection space not only provides convenient conditions for the detection of the hydrogen storage well at any time, but also avoids the hydrogen storage well from being squeezed by direct contact with the surrounding soil and groundwater during daily operation, as well as corrosion caused by the surrounding soil, microorganisms, salt water, etc., thereby reducing the impact of the surrounding environment and increasing the service life of the hydrogen storage well.

[0056] In certain embodiments, the nondestructive testing technique is ultrasonic nondestructive testing.

[0057] In practical applications, ultrasonic nondestructive testing is the most frequently used and fastest growing detection technology in the field of nondestructive testing, and is widely used in the field of industrial flaw detection.

[0058] In some embodiments, the ultrasonic nondestructive testing includes an ultrasonic probe 7 and an adjusting device for adjusting the position of the ultrasonic probe 7 in the testing space outside the well;

[0059] The adjusting device includes a circumferential track 4, a circumferential sliding bracket 12, a protruding device 17 and a circumferential magnetic control device 18;

[0060] The annular track 4 is arranged on the ground outside the upper opening of the shaft 5, is coaxially arranged with the shaft 5, and is connected to the annular sliding bracket 12 in a moving pair;

[0061] A plurality of pulleys 11 are provided between the annular sliding bracket 12 and the annular track 4 to form a moving pair, and a protruding device 17 and an annular magnetic control device 18 are provided through a fixed bracket;

[0062] The extending device 17 suspends the ultrasonic probe 7 through the self-controlled cable 15 to realize the vertical reciprocating movement of the ultrasonic probe 7 relative to the magnetically controlled vertical adjustment device 13;

[0063] The circumferential magnetic control device 18 controls the circumferential sliding bracket 12 to move along the circumferential track 4 .

[0064] The present invention uses an automatic control system based on the electromagnetic induction principle in the detection space outside the well to control the ultrasonic probe 7 to complete the automatic detection of the circumferential and vertical combination of the hydrogen storage well outside the well, which greatly improves the detection efficiency and accuracy and ensures that there are no omissions in the detection.

[0065] During the inspection, the rotation of the cable shaft is controlled by the electromagnetic automatic control system, and the number of rotations or angles of the cable when passing through is detected by the speed sensor, so as to automatically measure the length, speed and other parameters of the cable lowering, and accurately display them on the CNC display screen, so as to realize the vertical positioning of the ultrasonic probe at the end of the cable. An annular sliding bracket is set at the wellhead, and a pulley is provided at the bottom of the bracket, which can slide along the annular track pre-set on the wellhead ground. An adjustable extension device is also provided on the bracket, and the cable is set on the extension device. During the inspection, the length of the extension device can be adjusted according to actual needs, so as to control the horizontal distance between the ultrasonic probe and the hydrogen storage wellbore. During the annular inspection, the annular magnetic control device of the sliding bracket will control the circumferential sliding of the pulley, thereby driving the ultrasonic probe to complete the annular inspection of the wellbore.

[0066] In some embodiments, the ultrasound probe 7 is provided with a CCTV device;

[0067] A numerical control display screen 1 is provided outside the wellbore 5 for displaying the working status of the regulating device and the collection results of the ultrasonic probe 7 .

[0068] In practical applications, the ultrasonic probe 7 with CCTV device can display the video image in the detection space outside the well in real time, so that the ground detection personnel can clearly understand the structure and condition of the wellbore 5, which is convenient for subsequent pipeline maintenance, repair and modification work.

[0069] In some embodiments, ultrasonic nondestructive testing uses phased array ultrasonic testing technology, and the coupling method is liquid immersion.

[0070] From the perspective of the coupling mode between the ultrasonic probe 7 and the workpiece, ultrasonic nondestructive testing can be divided into two categories: contact method and liquid immersion method. Among them, the liquid immersion method has higher resolution, sensitivity and reliability.

[0071] In some embodiments, the water immersion thickness h of the liquid immersion method, that is, the method for selecting the coupling layer is as follows:

[0072] Step 1: Calculate the water immersion thickness h. The specific formula is as follows:

[0073]

[0074] Where D is the diameter of the probe wafer, in mm; a is the ultrasonic wavelength, in mm; V 水 V is the speed of sound of longitudinal waves in water, unit: 1483 m / s; 井 is the speed of sound in the well wall, in m / s; L is the thickness of the well wall in the detection direction, in mm;

[0075] Step 2: Based on the water immersion thickness, conduct detection tests with different water layer thicknesses, analyze the echo conditions under different water layer thicknesses, and obtain the optimal water layer thickness selection range.

[0076] In some embodiments, the bottom hole seal 8 at the bottom of the wellbore 5 is sealed with the wellbore 5 without leakage; the bottom hole seal 8 and the outer wall retaining wall 6 are sealed with oil well cement 9.

[0077] A cementing device 14 is provided at the wellhead 16 at the upper end of the wellbore 5;

[0078] The cementing device 14 includes a horizontal plate and supports disposed on both sides of the horizontal plate for fixing the horizontal plate;

[0079] A hole matching the wellhead 16 is provided near the middle of the horizontal plate, and the wellhead 16 is reinforced by being sleeved on the outside of the wellhead 16 through the hole.

[0080] If necessary, anchors such as anchor rods, anchor cables, etc. may be installed at the bottom of the wellbore 5. These anchors can penetrate into the underground rock layer or soil layer to provide additional fixing and support. Through the solidification of the oil well cement, the anchors can be firmly combined with the casing and the formation to form a stable overall structure.

[0081] In practical applications, the above-mentioned technical means can ensure the stability of the wellbore 5 of the hydrogen storage well.

[0082] In some embodiments, reinforced concrete material is used outside the wellbore 5 to form a cementing clamp device.

[0083] In practical applications, the cementing clamp device outside the wellbore 5 ensures the fixing effect of the wellbore 5 of the hydrogen storage well in the vertical direction.

[0084] The present invention also provides a detection method, using the above-mentioned hydrogen storage well outer annular and vertical combined non-destructive detection device to detect the wellbore 5, and the specific steps are as follows:

[0085] Step 1: Fill the annular detection space with water through the centrifugal pump 13 and the drainage / injection pipe 10;

[0086] Step 2: Use numerical control technology to compile a program-designed detection path, control the ultrasonic probe 7 to start from a position flush with the wellhead of the wellbore 5, control the ultrasonic probe 7 to rotate clockwise along the wellbore 5 through the annular sliding bracket 12, stimulate the piezoelectric chip to generate ultrasonic waves through electrical signals, and control the excitation time of each chip to achieve focusing and scanning of the ultrasonic beam;

[0087] Step 3: After the focusing and scanning are completed by rotating clockwise for one circle, the ultrasonic probe 7 is moved downward for a certain distance through the automatic control cable 15 of the ultrasonic probe 7, and then rotated counterclockwise for one circle to complete the focusing and scanning;

[0088] Step 4: Repeat steps 2 and 3 until the entire surface area of ​​the wellbore 5 is focused and scanned.

[0089] In some embodiments, the movement rate of the ultrasonic probe 7 is uniform, and the movement distance between each focusing and scanning, as well as the distance of each downward movement are smaller than the scanning width of the ultrasonic probe 7, so that there is at least 15% overlap between the sampling results obtained from every two adjacent focusing and scanning.

[0090] In practical applications, the above technical means can ensure 100% combined circumferential and vertical detection during the scanning process.

[0091] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A combined circumferential and vertical nondestructive testing device for a hydrogen storage well; characterized in that: It comprises a tubular outer wall retaining wall (6) arranged outside a wellbore (5) located underground and extending along the length direction of the wellbore (5); An out-of-well detection space is formed between the outer wall retaining wall (6) and the wellbore (5); Nondestructive testing technology is used in the detection space outside the well to detect defects and damages of the wellbore (5), and remote operation and data transmission are realized by combining digital means; The non-destructive testing technology is ultrasonic non-destructive testing; The ultrasonic non-destructive testing comprises an ultrasonic probe (7) and an adjusting device for adjusting the position of the ultrasonic probe (7) in the detection space outside the well; The regulating device comprises a circumferential track (4), a circumferential sliding bracket (12), a protruding device (17) and a circumferential magnetic control device (18); The annular track (4) is arranged on the ground outside the upper opening of the shaft (5), is coaxially arranged with the shaft (5), and is connected to the annular sliding bracket (12) in a movable pair; A plurality of pulleys (11) are provided between the annular sliding bracket (12) and the annular track (4) to form the moving pair, and the extending device (17) and the annular magnetic control device (18) are provided via a fixed bracket; The extending device (17) suspends the ultrasonic probe (7) via a self-controlled cable (15) to achieve vertical reciprocating movement of the ultrasonic probe (7) relative to the magnetically controlled vertical adjustment device (13); The annular magnetic control device (18) controls the annular sliding bracket (12) to move along the annular track (4); The other end of the automatic control cable (15) is wound around a cable shaft (2) located outside the wellbore (5), and the length of the portion entering the wellbore (5) is collected by a rotation sensor (3).

2. The combined circumferential and vertical nondestructive testing device for a hydrogen storage well according to claim 1, characterized in that: The ultrasonic probe (7) is provided with a CCTV device; The wellbore (5) is provided with a numerical control display screen (1) outside for displaying the working state of the regulating device and the collection results of the ultrasonic probe (7).

3. The combined circumferential and vertical nondestructive testing device for a hydrogen storage well according to claim 1, characterized in that: The ultrasonic nondestructive testing adopts phased array ultrasonic testing technology, and the coupling method is liquid immersion method.

4. The combined circumferential and vertical nondestructive testing device for a hydrogen storage well according to claim 3, characterized in that: The water immersion thickness h of the immersion method, i.e., the method for selecting the coupling layer is as follows: Step 1: Calculate the water immersion thickness h. The specific formula is as follows: Where D is the diameter of the probe wafer, in mm; a is the ultrasonic wavelength, in mm; V 水 V is the speed of sound of longitudinal waves in water, unit: 1483 m / s; 井 is the speed of sound in the well wall, in m / s; L is the thickness of the well wall in the detection direction, in mm; Step 2: Based on the water immersion thickness, through detection tests of different water layer thicknesses, analyze the echo conditions under different water layer thicknesses to obtain the optimal water layer thickness selection range.

5. The combined circumferential and vertical nondestructive testing device for a hydrogen storage well according to claim 1, characterized in that: The well bottom seal (8) at the bottom of the wellbore (5) and the wellbore (5) are sealed without leakage; the well bottom seal (8) and the outer wall retaining wall (6) are sealed with oil well cement (9); A cementing device (14) is provided at the wellhead (16) at the upper end of the wellbore (5); The cementing device (14) comprises a horizontal plate and supports arranged on both sides of the horizontal plate for fixing the horizontal plate; The horizontal plate is provided with a hole matching the wellhead (16) near the middle position, and the wellhead (16) is reinforced by being sleeved on the outside of the wellhead (16) through the hole.

6. The combined circumferential and vertical nondestructive testing device for a hydrogen storage well according to claim 1, characterized in that: The outside of the wellbore (5) is made of reinforced concrete material to form a cementing hoop device.

7. A detection method, characterized in that The wellbore (5) is inspected using the combined circumferential and vertical nondestructive testing device for the hydrogen storage well as claimed in claim 1, and the specific steps are as follows: Step 1: Fill the annular detection space with water through a centrifugal pump (13) and a water discharge / injection pipe (10); Step 2, using numerical control technology to compile a program-designed detection path, control the ultrasonic probe (7) to start from a position flush with the wellhead of the wellbore (5), control the ultrasonic probe (7) to rotate clockwise along the wellbore (5) through the annular sliding bracket (12), stimulate the piezoelectric chip to generate ultrasonic waves through electrical signals, and control the excitation time of each chip to achieve focusing and scanning of the ultrasonic beam; Step 3, after completing focusing and scanning by rotating in a clockwise direction for one circle, the ultrasonic probe (7) is moved downward for a certain distance through the automatic control cable (15) of the ultrasonic probe (7), and then rotating in a counterclockwise direction for one circle to complete focusing and scanning; Step 4: Repeat steps 2 and 3 until the entire surface area of ​​the wellbore (5) is focused and scanned.

8. The detection method according to claim 7, characterized in that: The ultrasonic probe (7) has a uniform moving speed, and the moving distance between each focusing and scanning, as well as the moving distance each time downward, are smaller than the scanning width of the ultrasonic probe (7), so that there is at least 15% overlap between the sampling results obtained by every two adjacent focusing and scanning.

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