A detection method, device and medium for eddy current diffusion based on a circular array

Abstract

An embodiment of the present invention discloses a detection method, device and medium for eddy current diffusion based on a circular array; the method includes: obtaining the magnetic field distribution of the non-symmetric damage azimuth-eddy current diffusion time dimension at different damage degrees at a set depth position according to the circumferential azimuth dimension information of the casing received by the eccentric probe distributed in a circular array; determining a first correspondence relationship between the eddy current diffusion time and the circumferential radius of the casing at the set depth position based on the magnetic field distribution of the non-symmetric damage azimuth-eddy current diffusion time dimension of the casing at different damage degrees at the set depth position; determining a second correspondence relationship between the circumferential azimuth dimension information of the casing and the circumferential radius of the casing; obtaining the two-dimensional shape of the non-symmetric damage of the casing in the radial direction at the set depth position based on the first correspondence relationship and the second correspondence relationship; obtaining the three-dimensional shape of the non-symmetric damage of the casing according to the two-dimensional shapes and circumferential azimuths of the non-symmetric damage of the casing in the radial direction at multiple different set depth positions.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of oil and gas field equipment detection, and particularly to a detection method, device and medium based on eddy current diffusion of a circular array. Background Technique

[0002] With the continuous deepening of oil and water well operations, the damage of downhole casing appears more and more, such as corrosion, deformation, misalignment, etc. Affected by uneven formation pressure, these damages are basically asymmetric. The pulsed eddy current technology can provide rich broadband information due to the eddy current diffusion brought by the emission excitation, which helps to identify the situation of different downhole media in the radial direction from the eddy current diffusion time. Currently, it has been widely used in the field of casing damage detection. However, most of the existing pulsed eddy current casing damage detection systems use a centered probe that coincides with the wellbore axis. Its received response contains comprehensive information in the 360-degree direction around the wellbore. Using this comprehensive information, it is impossible to detect the asymmetric damage in a specific direction of the casing. To solve this problem, more and more scholars have proposed a pulsed eddy current detection method based on an eccentric probe. By using an eccentric probe with its center deviated from the wellbore axis, more casing information in the direction where the eccentric probe is offset can be obtained. By arranging multiple eccentric probes circumferentially around the casing to form a circular array, azimuth dimension detection information is introduced, and by comparing the received responses of multiple eccentric probes in the circular array, damage detection in multiple directions around the wellbore can be achieved, and then the detection of asymmetric damage of the casing can be realized.

[0003] However, the existing methods can only achieve qualitative judgment of the asymmetric damage of the casing, such as the approximate azimuth of the damage, the approximate circumferential width, the approximate circumferential shape, etc., and cannot quantitatively analyze the asymmetric damage conditions on the inner and outer walls of the casing, such as the radial penetration depth of the damage, the specific type of the damage, etc. The main reason is that the eddy current diffusion time is not corresponded with the radial information of the medium around the wellbore, especially the eddy current diffusion time is not matched with the casing wall thickness. Therefore, if the eddy current diffusion time can be corresponded with the casing wall thickness, and the casing radius can be corresponded with the circumferential angle, the imaging of the detection information between the inner and outer walls of the casing can be realized, and then the three-dimensional shape detection of the asymmetric damage on the casing can be realized. Summary of the Invention

[0004] In view of this, the embodiments of the present invention are expected to provide a detection method, device and medium based on eddy current diffusion of a circular array; which can realize the three-dimensional shape detection of the asymmetric damage of the casing based on the corresponding relationship between the eddy current diffusion time and the circumferential radius of the casing, and in combination with the corresponding relationship between the circumferential radius of the casing and the circumferential azimuth.

[0005] The technical solution of the embodiments of the present invention is realized as follows:

[0006] In a first aspect, an embodiment of the present invention provides a detection method for eddy current diffusion based on a circular array. The detection method includes:

[0007] Obtain the magnetic field distribution of the non-symmetric damage azimuth - eddy current diffusion time dimension of the casing at different damage degrees at a set depth position according to the circumferential azimuth dimension information of the casing received by the eccentric probe distributed in a circular array;

[0008] Based on the magnetic field distribution of the non-symmetric damage azimuth - eddy current diffusion time dimension of the casing at different damage degrees at a set depth position, determine the first correspondence between the eddy current diffusion time and the circumferential radius of the casing at the set depth position;

[0009] Determine the second correspondence between the circumferential azimuth dimension information of the casing and the circumferential radius of the casing;

[0010] Based on the first correspondence and the second correspondence, obtain the two-dimensional shape of the non-symmetric damage of the casing in the radial direction at the set depth position;

[0011] According to the two-dimensional shapes and circumferential azimuths of the non-symmetric damage of the casing in the radial direction at multiple different set depth positions, obtain the three-dimensional shape of the non-symmetric damage of the casing.

[0012] In a second aspect, an embodiment of the present invention provides a detection device for eddy current diffusion based on a circular array. The detection device includes: a first acquisition part, a first determination part, a second determination part, a second acquisition part, and a third acquisition part; wherein,

[0013] The first acquisition part is configured to obtain the magnetic field distribution of the non-symmetric damage azimuth - eddy current diffusion time dimension of the casing at different damage degrees at a set depth position according to the circumferential azimuth dimension information of the casing received by the eccentric probe distributed in a circular array;

[0014] The first determination part is configured to determine the first correspondence between the eddy current diffusion time and the circumferential radius of the casing at the set depth position based on the magnetic field distribution of the non-symmetric damage azimuth - eddy current diffusion time dimension of the casing at different damage degrees at a set depth position;

[0015] The second determination part is configured to determine the second correspondence between the circumferential azimuth dimension information of the casing and the circumferential radius of the casing;

[0016] The second acquisition part is configured to obtain the two-dimensional shape of the non-symmetric damage of the casing in the radial direction at the set depth position based on the first correspondence and the second correspondence;

[0017] The third acquisition part is configured to obtain a three-dimensional shape of the asymmetric damage of the casing according to two-dimensional shapes and circumferential orientations of the asymmetric damage of the casing in the radial direction at a plurality of different set depth positions.

[0018] In a third aspect, an embodiment of the present invention provides a medium storing a detection program based on circular array eddy current diffusion. When the detection program based on circular array eddy current diffusion is executed by at least one processor, steps of the detection method based on circular array eddy current diffusion described in the first aspect are implemented.

[0019] An embodiment of the present invention provides a detection method, device and medium for circular array eddy current diffusion. By using circumferential orientation dimension information of a casing received by eccentric probes distributed in a circular array, a magnetic field distribution of the asymmetric damage azimuth-eddy current diffusion time dimension of the casing at different damage degrees at a set depth position is obtained. Then, a first corresponding relationship between the eddy current diffusion time and the circumferential radius of the casing at the set depth position is determined. Furthermore, in combination with a second corresponding relationship between the circumferential orientation dimension information of the casing and the circumferential radius of the casing, a two-dimensional shape of the asymmetric damage of the casing in the radial direction at the set depth position is obtained. Finally, based on two-dimensional shapes and circumferential orientations of the asymmetric damage in the radial direction at a plurality of different set depth positions, a three-dimensional shape of the asymmetric damage on the casing is obtained. By using this detection method, the problem that the degree of asymmetric damage between the inner and outer walls of the casing cannot be quantitatively judged in the existing method can be solved, and three-dimensional shape detection of the asymmetric damage of the downhole casing can be realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of an asymmetric damage model of a casing provided by an embodiment of the present invention;

[0021] Figure 2 It is a schematic flowchart of a detection method based on circular array eddy current diffusion provided by an embodiment of the present invention;

[0022] FIG. 3(a) is a schematic diagram of a magnetic field distribution of an asymmetric damage azimuth-eddy current diffusion time dimension of a non-damaged casing provided by an embodiment of the present invention;

[0023] FIG. 3(b) is a schematic diagram of a magnetic field distribution of an asymmetric damage azimuth-eddy current diffusion time dimension of a casing with a damage degree of 20% provided by an embodiment of the present invention;

[0024] FIG. 3(c) is a schematic diagram of a magnetic field distribution of an asymmetric damage azimuth-eddy current diffusion time dimension of a casing with a damage degree of 40% provided by an embodiment of the present invention;

[0025] FIG. 3(d) is a schematic diagram of a magnetic field distribution of an asymmetric damage azimuth-eddy current diffusion time dimension of a casing with a damage degree of 60% provided by an embodiment of the present invention;

[0026] Figure 3(e) is a schematic diagram of the magnetic field distribution of the non-symmetric damage orientation - eddy current diffusion time dimension of the casing when the damage degree is 80% provided by the embodiment of the present invention;

[0027] Figure 3(f) is a schematic diagram of the magnetic field distribution of the non-symmetric damage orientation - eddy current diffusion time dimension of the casing when the damage degree is 100% provided by the embodiment of the present invention;

[0028] Figure 4 It is a schematic diagram of the change of the normalized magnetic flux density modulus in the 0-degree direction with the eddy current diffusion time when different degrees of damage are provided by the embodiment of the present invention;

[0029] Figure 5 It is a schematic diagram of the coordinate transformation provided by the embodiment of the present invention;

[0030] Figure 6(a) is a schematic diagram of the magnetic field distribution of the non-symmetric damage orientation - casing circumferential radius dimension of the casing without damage provided by the embodiment of the present invention;

[0031] Figure 6(b) is a schematic diagram of the magnetic field distribution of the non-symmetric damage orientation - casing circumferential radius dimension of the casing when the damage degree is 20% provided by the embodiment of the present invention;

[0032] Figure 6(c) is a schematic diagram of the magnetic field distribution of the non-symmetric damage orientation - casing circumferential radius dimension of the casing when the damage degree is 40% provided by the embodiment of the present invention;

[0033] Figure 6(d) is a schematic diagram of the magnetic field distribution of the non-symmetric damage orientation - casing circumferential radius dimension of the casing when the damage degree is 60% provided by the embodiment of the present invention;

[0034] Figure 6(e) is a schematic diagram of the magnetic field distribution of the non-symmetric damage orientation - casing circumferential radius dimension of the casing when the damage degree is 80% provided by the embodiment of the present invention;

[0035] Figure 6(f) is a schematic diagram of the magnetic field distribution of the non-symmetric damage orientation - casing circumferential radius dimension of the casing when the damage degree is 100% provided by the embodiment of the present invention;

[0036] Figure 7 It is a schematic diagram of the two-dimensional shape of the non-symmetric damage when the damage degree is 80% provided by the embodiment of the present invention;

[0037] Figure 8 It is a schematic diagram of the composition of a detection device for eddy current diffusion based on a circular array provided by the embodiment of the present invention;

[0038] Figure 9 It is a schematic diagram of the hardware structure of a computing device provided by the embodiment of the present invention. Detailed implementation manners

[0039] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention.

[0040] In the prior art, the pulsed eddy current damage detection method mainly uses the time-domain diffusion characteristics of pulsed eddy current to detect the remaining wall thickness of the casing. For the asymmetric damage on the casing, an eccentric probe distributed in a circular array can introduce the detection information of the circumferential azimuth dimension of the casing to obtain the detection information such as the azimuth, circumferential width, and circumferential shape of the asymmetric damage. However, for whether the asymmetric damage occurs on the outer wall or the inner wall of the casing, and the specific degree of asymmetric damage between the inner wall and the outer wall of the casing, the existing pulsed eddy current detection methods cannot judge. However, the detection information of pulsed eddy current contains rich broadband characteristics, and the information containing the casing wall thickness can be extracted from the detection information of the eccentric probe by analyzing the corresponding relationship between the eddy current diffusion signals at different detection times at a set depth position and the casing wall thickness. On this basis, by matching the azimuth dimension information received by the eccentric probe with the wall thickness information of the casing circumference, the two-dimensional shape between the inner and outer walls of the casing at the set depth position of the casing can be imaged. Furthermore, by combining the detection information at multiple different set depth positions, the three-dimensional shape detection of the asymmetric damage of the casing can be realized.

[0041] Based on the above description, the embodiments of the present invention are expected to provide a detection scheme based on the eddy current diffusion of a circular array, in order to expect to detect the three-dimensional shape of the asymmetric damage on the casing through an eccentric probe distributed in a circular array. Before elaborating on the embodiments of the present invention in detail, it is assumed that there is a damage of the hole type on the casing, the normal direction of the hole is perpendicular to the wellbore axis, the radius of the hole is 1 cm, and it penetrates the inner and outer walls of the casing. In the embodiments of the present invention, the direction where the damage center of the above hole is located is defined as the 0-degree direction, so that the hole-type asymmetric damage model as shown in Figure 1 can be established. Specifically, Figure 1 the shown asymmetric damage model from the outside to the inside is the formation, the casing, and the caliper logging tool. The eccentric probe is placed in the caliper logging tool to detect and receive the damage information on the casing. It can be understood that each eccentric probe is composed of a magnetic core and a coil wound around the magnetic core. It should be noted that in the embodiments of the present invention, the eccentric probe can select a giant magnetoresistance (GMR) receiving sensor.

[0042] In order to be able to detect the above hole-type asymmetric damage by using an eccentric probe distributed in a circular array, see Figure 2 , which shows a detection method based on the eddy current diffusion of a circular array provided by the embodiments of the present invention. The detection method includes:

[0043] S201. Obtain the magnetic field distribution of the non-symmetric damage azimuth - eddy current diffusion time dimension of the casing at a set depth position with different damage degrees according to the circumferential azimuth dimension information of the casing received by the eccentric probes distributed in a circular array.

[0044] S202. Based on the magnetic field distribution of the non-symmetric damage azimuth - eddy current diffusion time dimension of the casing at a set depth position with different damage degrees, determine the first corresponding relationship between the eddy current diffusion time and the circumferential radius of the casing at the set depth position.

[0045] S203. Determine the second corresponding relationship between the circumferential azimuth dimension information of the casing and the circumferential radius of the casing.

[0046] S204. Based on the first corresponding relationship and the second corresponding relationship, obtain the two-dimensional shape of the non-symmetric damage of the casing in the radial direction at the set depth position.

[0047] S205. According to the two-dimensional shapes and circumferential azimuths of the non-symmetric damage of the casing in the radial direction at multiple different set depth positions, obtain the three-dimensional shape of the non-symmetric damage of the casing.

[0048] For Figure 2 For the technical solution shown, according to the circumferential azimuth dimension information of the casing received by the eccentric probes distributed in a circular array, obtain the magnetic field distribution of the non-symmetric damage azimuth - eddy current diffusion time dimension of the casing at a set depth position with different damage degrees; then determine the first corresponding relationship between the eddy current diffusion time and the circumferential radius of the casing at the set depth position; furthermore, combine the second corresponding relationship between the circumferential azimuth dimension information of the casing and the circumferential radius of the casing to obtain the two-dimensional shape of the non-symmetric damage of the casing in the radial direction at the set depth position, and finally, based on the two-dimensional shapes and circumferential positions of the non-symmetric damage in the radial direction at multiple different set depth positions, obtain the three-dimensional shape of the non-symmetric damage on the casing. Through this detection method, the problem that the non-symmetric damage degree between the inner and outer walls of the casing cannot be quantitatively judged in the existing methods can be solved, and the three-dimensional shape detection of the non-symmetric damage of the downhole casing can be realized.

[0049] For Figure 2 For the technical solution shown, it should be noted that in the embodiment of the present invention, by applying a pulse excitation to the transmitting coil and using the eccentric probes distributed in a circular array to receive the measurement signal during the off-gap of the pulse excitation, the received measurement signal contains the circumferential azimuth dimension information of the casing. Therefore, the circumferential azimuth dimension information of the casing can be introduced into the non-symmetric damage detection system of the casing, and it can be understood that the more the number of eccentric probes in the circular array, the higher the circumferential azimuth resolution of the casing.

[0050] It can be understood that for Figure 1In the asymmetric damage model shown in FIG, the receiving response of the eccentric probe that is biased toward the damage direction will be different from the receiving response of the other eccentric probes that are not biased toward the damage direction. By analyzing the difference in the above receiving responses, it can be determined that Figure 1 The orientation, circumferential width and circumferential shape of the hole-type asymmetric damage are shown.

[0051] However, it is not possible to determine the Figure 1 The specific situation of the hole-type asymmetric damage in the radial direction of the casing is shown in the figure. Therefore, it is necessary to further obtain Figure 1 The penetration of the asymmetric hole-type damage in the radial direction of the casing is shown.

[0052] In addition, it should be noted that in the embodiment of the present invention, the setting Figure 1 The holes shown are from the outer wall to the inner wall of the casing, and the damage degree (also known as "penetration depth") is set to 0% (that is, complete casing), 20%, 40%, 60%, 80% and 100% of the casing wall thickness, where the damage degree of 100% corresponds to Figure 1 The damage in the model shown. Then, in the specific implementation process, the time domain diffusion characteristics of the pulse eddy current generated by the eccentric probe can be used to fix the detection depth z=0, and the imaging of the eddy current magnetic field distribution in the asymmetric damage azimuth-eddy current diffusion time dimension of the casing at different damage degrees can be obtained, as shown in Figures 3 (a)-3 (f); It should be noted that the above detection depth z refers to the longitudinal depth position of the center of the transmitting coil along the well axis. It can be understood that in the imaging results shown in Figures 3 (a)-3 (f) at the detection depth z=0, the center of the hole damage is located in the 0 degree direction, which is completely consistent with the actual azimuth information of the hole; on the other hand, as the degree of hole damage gradually increases from the outer wall to the inner wall of the casing, the damage boundary gradually approaches the inner wall of the casing, and the zero-sink edge in the 0 degree direction in Figures 3 (a)-3 (f) gradually approaches the early stage, that is, as the hole damage gradually increases, it is easier to detect the zero-sink distribution where the damage center is located in the early stage of eddy current diffusion. Therefore, the magnetic field distribution imaging results based on the annular azimuth-eddy current diffusion time dimension can well distinguish the annular and radial information of asymmetric damage.

[0053] for Figure 2 In some possible implementations of the technical solution shown, based on the magnetic field distribution of the asymmetric damage azimuth-eddy current diffusion time dimension of the casing at different damage degrees at the set depth position, determining the first corresponding relationship between the eddy current diffusion time at the set depth position and the circumferential radius of the casing includes:

[0054] According to the magnetic field distribution of the non - symmetric damage orientation - eddy current diffusion time dimension of the casing at different damage degrees at the set depth position, extract the eddy current diffusion time corresponding to the null in the direction where the damage center is located;

[0055] Based on the eddy current diffusion time corresponding to the null in the direction where the damage center is located, determine the first corresponding relationship between the eddy current diffusion time and the circumferential radius of the casing.

[0056] For the above - mentioned possible implementation manners, in some examples, the determining the first corresponding relationship between the eddy current diffusion time and the circumferential radius of the casing based on the eddy current diffusion time corresponding to the null in the direction where the damage center is located includes:

[0057] Based on the change trend of the eddy current diffusion time corresponding to the null in the direction where the damage center is located, obtain the change trend of the normalized magnetic flux density modulus in the direction where the damage center is located for different degrees of damage;

[0058] According to the change trend of the normalized magnetic flux density modulus in the direction where the damage center is located for different degrees of damage, obtain the eddy current diffusion time when the normalized magnetic flux density modulus reaches a peak for different degrees of damage;

[0059] According to the eddy current diffusion time when the normalized magnetic flux density modulus reaches a peak for different degrees of damage, determine that the first corresponding relationship between the eddy current diffusion time and the circumferential radius of the casing is:

[0060] (1)

[0061] where 、 and are constants.

[0062] It should be noted that as shown in Figure 4 , with the change of the eddy current diffusion time, the normalized magnetic flux density modulus in the central direction of the hole damage under different damage degrees will reach a peak. Figure 4 The abscissa corresponding to the peak in r, the eddy current diffusion time t and the circumferential radius of the casing r The first corresponding relationship can be fitted and described as:

[0063] (1)

[0064] It should be noted that the circumferential radius of the casing r also includes the actual radius of the damaged part on the casing.

[0065] In the specific implementation process, by substituting the peak times of 3.0 ms and 4.6 ms of the eddy current diffused to the outer wall and the inner wall of the casing and the corresponding radius at the damaged edge r into equation (1), the fitting gives A = 0.01716, B = 0.9291, C = 5.809. It should be noted that as the damage morphology changes, the parameters A , B and C may also change. However, since the received signals of the eccentric probe corresponding to different eddy current diffusion times all contain the asymmetric damage information of the casing, the slight change of the parameters will not affect the identification of the damage morphology.

[0066] Therefore, based on the real-time detection of the eddy current diffusion time, the actual radius of the asymmetric damage on the casing can be obtained according to the first corresponding relationship, and then the actual wall thickness of the damaged part of the casing can be obtained, which helps to determine the two-dimensional morphology of the asymmetric damage on the casing in the specific implementation process.

[0067] For Figure 2 the technical solution shown, in some possible implementation manners, the determining the second corresponding relationship between the circumferential azimuth dimension information of the casing and the circumferential radius of the casing includes:

[0068] Setting a plurality of sampling points on the peak time periods when the eddy current diffuses to the inner and outer walls of the casing, and obtaining the first received response of the eccentric probe within the sampling time periods corresponding to the plurality of sampling points as:

[0069] (2)

[0070] Wherein, P and Q respectively represent the sampling points; K represents the number of GMR receiving sensors included in the eccentric probe; L represents the total number of sampling points; wherein, 1 ≤ P, Q ≤ L and P < Q;

[0071] The first reception response of the eccentric probe within the sampling time periods corresponding to the multiple sampling points is transformed according to Equation (3) to obtain the second reception response of the eccentric probe in the polar coordinate system;

[0072] (3)

[0073] where the ordered pair represents the point in the rectangular coordinate system corresponding to the coordinates in the polar coordinate system, where represents the polar radius, represents the polar angle; when takes P to Q , the polar radius and the polar radius respectively represent the inner wall radius r inner and the outer wall radius r outer ; as l and k change, the signal value of the region enclosed by and is ; when l takes P to Q , k takes 1 to K , the corresponding polar coordinate region represents the region between the inner and outer walls of the casing;

[0074] where the transformation relationship formula (3) between the first reception response and the second reception response is used to characterize the second corresponding relationship.

[0075] Specifically, the sampling time periods corresponding to the peak times when the eddy current diffuses to the inner and outer walls of the casing are respectively denoted as P and Q , then the reception response within this sampling time period can be written as:

[0076] (2)

[0077] where K is the number of GMR reception sensors included in the eccentric probe, L is the total number of sampling points, 1 ≤ P , Q ≤ L and P < Q .

[0078] To obtain the relationship between the circumferential radius of the casing and the circumferential angle, the circumferential azimuth - eddy diffusion time - dimension data containing Equation (2) in the rectangular coordinate system of Figures 3(a) - 3(f) is transformed into the circumferential azimuth - circumferential radius of the casing - dimension data in the polar coordinate system. Assume that K = 8, then the corresponding relationship of the data before and after the coordinate transformation is as Figure 5 shown.

[0079] Therefore, the transformation relationship between the rectangular coordinate system and the polar coordinate system between the inner and outer walls of the casing can be obtained as:

[0080] (3)

[0081] In Equation (3), the ordered pair ( ρ l , θ k ) is the coordinate in the polar coordinate system corresponding to the point ( l , k ) in the rectangular coordinate system. ρ l is the polar radius, θ k is the polar angle. When l takes P to Q , the polar radius ρ P and ρ Q respectively correspond to the inner wall r inner and the outer wall r outer of the casing. As l and k change, the signal value of the region enclosed by ( ρ l , θ k ) and ( ρ l+1 , θ k+1 ) is U l,k . When l takes P to Q , k takes 1 to K , the corresponding polar coordinate region is the region between the inner and outer walls of the casing.

[0082] In the specific implementation process, Equation (3) can be used to represent the second corresponding relationship between the circumferential azimuth dimension information of the casing and the circumferential radius of the casing.

[0083] For Figure 2In some possible implementation manners of the technical solution shown, obtaining the two-dimensional shape of the asymmetric damage of the casing in the radial direction at the set depth position based on the first correspondence and the second correspondence includes:

[0084] Based on the first correspondence, obtain the circumferential radius of the casing; wherein, the circumferential radius of the casing is used to characterize the wall thickness at the asymmetric damage of the casing;

[0085] Based on the second correspondence, convert the magnetic field distribution of the azimuth-eddy current diffusion time dimension of the asymmetric damage of the casing at different damage degrees at the set depth position into the magnetic field distribution between the inner and outer walls of the casing in the polar coordinate system;

[0086] According to the magnetic field distribution between the inner and outer walls of the casing in the polar coordinate system, determine the two-dimensional shape of the asymmetric damage of the casing in the radial direction at the set depth position.

[0087] For the above possible implementation manners, in some examples, the determining the two-dimensional shape of the asymmetric damage of the casing in the radial direction at the set depth position according to the magnetic field distribution between the inner and outer walls of the casing in the polar coordinate system includes:

[0088] According to the magnetic field distribution between the inner and outer walls of the casing in the polar coordinate system, determine the size of the asymmetric damage of the casing in the radial direction and the included angle between the asymmetric damage and the eccentric probe.

[0089] According to Equation (3), the corresponding first received response can be assigned to the corresponding position to obtain the second received response in the polar coordinate system, and then the magnetic field distribution between the inner and outer walls of the casing in the polar coordinate system can be obtained. Specifically, using the above method to process the magnetic field distributions of the azimuth-eddy current diffusion time dimensions with different damage degrees shown in FIGS. 3(a)-3(f), the circumferential azimuth-casing circumferential radius dimension magnetic field distribution between the inner and outer walls of the casing in the polar coordinate system can be obtained as shown in FIGS. 6(a)-6(f).

[0090] Analyzing the magnetic field distribution imaging results shown in FIGS. 6(a)-6(f), it can be seen that the damage degrees of the casing from the outer wall to the inner wall are different, and the ranges of the null edge are different. The position of the null edge between the inner and outer walls of the casing basically coincides with the edge position of the asymmetric damage on the casing. At the same time, the circumferential azimuth-casing circumferential radius dimension magnetic field distribution between the inner and outer walls of the casing in the polar coordinate system is very close to Figure 1 the unfolded view of the asymmetric damage in the XOY plane. Therefore, according to the shape of the null region in the 0-degree direction in FIGS. 6(a)-6(f), the two-dimensional shape of the casing damage at the set depth position can be identified.

[0091] Specifically, taking the damage with a damage degree of 80% in Fig. 6(e) as an example, the damage shape identified according to the zero defect area is compared with the actual damage shape, as Figure 7 shown. In Figure 7 , the area S and the angle φ S are the damage size and the circumferential azimuth angle respectively identified according to the magnetic field distribution imaging schematic diagram of the circumferential azimuth - casing circumferential radius dimension between the inner and outer walls of the casing; the quadrilateral area surrounded by line segments AB, BD, l DC , and CA is the actual two - dimensional shape of the asymmetric damage at the depth where the eccentric probe center is located, and both ∠AOB and ∠COD are the angles between the asymmetric damage and the eccentric probe center. By comparing the recognition result with the actual damage shape, it can be seen that there are certain errors between the recognized damage size and circumferential azimuth angle and the actual values of the damage, which is mainly caused by the diffusion of eddy currents. However, according to the above magnetic field distribution imaging results, it is still possible to clearly distinguish the boundaries of different asymmetric damages between the inner and outer walls of the casing. That is to say, through the magnetic field distribution imaging results of the circumferential azimuth - casing circumferential radius dimension, the two - dimensional shape detection of the asymmetric damage of the casing in the radial direction at the set depth position can be realized.

[0092] Based on the two - dimensional shapes of the asymmetric damage detected at different depths in the circumferential azimuth and radial directions, by superimposing the two - dimensional damage information detected at each set depth position, the three - dimensional shape detection of the asymmetric damage on the casing can be realized.

[0093] Based on the same inventive concept as the foregoing technical solution, referring to Figure 8 , which shows a detection device 80 based on the eddy current diffusion of a circular array provided by an embodiment of the present invention. The detection device 80 includes: a first acquisition part 801, a first determination part 802, a second determination part 803, a second acquisition part 804, and a third acquisition part 805; wherein,

[0094] The first acquisition part 801 is configured to acquire the magnetic field distribution of the asymmetric damage azimuth - eddy current diffusion time dimension of the casing at different damage degrees at a set depth position according to the circumferential azimuth dimension information of the casing received by the eccentric probe distributed in a circular array;

[0095] The first determination part 802 is configured to determine a first correspondence relationship between the eddy current diffusion time and the casing circumferential radius at the set depth position based on the magnetic field distribution of the asymmetric damage azimuth - eddy current diffusion time dimension of the casing at different damage degrees at the set depth position;

[0096] The second determining part 803 is configured to determine a second corresponding relationship between the casing annular orientation dimension information and the casing circumferential radius;

[0097] The second acquisition part 804 is configured to acquire the two-dimensional morphology of the asymmetric damage of the casing in the radial direction at the set depth position based on the first corresponding relationship and the second corresponding relationship;

[0098] The third acquisition part 805 is configured to acquire the three-dimensional shape of the asymmetric damage of the casing according to the two-dimensional shape and circumferential orientation of the asymmetric damage of the casing in the radial direction at a plurality of different set depth positions.

[0099] In some examples, the first determining portion 802 is configured to:

[0100] According to the magnetic field distribution of the asymmetric damage azimuth-eddy current diffusion time dimension of the casing at different damage degrees at a set depth position, the eddy current diffusion time corresponding to the zero depression in the direction of the damage center is extracted;

[0101] Based on the eddy current diffusion time corresponding to the zero depression in the direction of the damage center, a first corresponding relationship between the eddy current diffusion time and the circumferential radius of the casing is determined.

[0102] In some examples, the first determining portion 802 is configured to:

[0103] Based on the variation trend of the eddy current diffusion time corresponding to the zero sink in the direction of the damage center, obtaining the variation trend of the normalized magnetic flux density modulus in the direction of the damage center when the damage is of different degrees;

[0104] According to the change trend of the normalized magnetic flux density modulus in the direction of the damage center when the damage is at different degrees, the eddy current diffusion time when the normalized magnetic flux density modulus appears at the peak value when the damage is at different degrees is obtained;

[0105] According to the eddy current diffusion time when the normalized magnetic flux density modulus appears at the peak value when the damage is different in degree, the first corresponding relationship between the eddy current diffusion time and the circumferential radius of the casing is determined as follows:

[0106] (1)

[0107] in, , and is a constant.

[0108] In some examples, the second determining portion 803 is configured to:

[0109] Set a plurality of sampling points during the peak time period when the eddy current diffuses to the inner and outer walls of the casing, and obtain the first reception response of the eccentric probe within the sampling time periods corresponding to the plurality of sampling points as:

[0110] (2)

[0111] Wherein, P and Q respectively represent the sampling points; K represents the number of GMR reception sensors included in the eccentric probe; L represents the total number of sampling points; wherein, 1 ≤ P, Q ≤ L and P <Q;

[0112] For the first reception response of the eccentric probe within the sampling time periods corresponding to the plurality of sampling points, perform a transformation according to Equation (3) to obtain the second reception response of the eccentric probe in the polar coordinate system;

[0113] (3)

[0114] Wherein, the ordered pair represents the point in the rectangular coordinate system corresponding to the coordinates in the polar coordinate system, where represents the polar radius, represents the polar angle; when takes P to Q , the polar radius and the polar radius respectively represent the inner wall radius r inner and the outer wall radius r outer ; as l and k change, and the signal value of the enclosed area is ; when l takes P to Q , k takes 1 to K , the corresponding polar coordinate area represents the area between the inner and outer walls of the casing;

[0115] Wherein, the transformation relationship formula (3) between the first reception response and the second reception response is used to characterize the second corresponding relationship.

[0116] In some examples, the second acquisition part 804 is configured to:

[0117] Based on the first correspondence, obtain the circumferential radius of the casing; wherein, the circumferential radius of the casing is used to characterize the wall thickness at the asymmetric damage of the casing.

[0118] Based on the second correspondence, convert the magnetic field distribution in the azimuth-eddy diffusion time dimension of the asymmetric damage of the casing at different damage degrees at the set depth position into the magnetic field distribution between the inner and outer walls of the casing in the polar coordinate system.

[0119] According to the magnetic field distribution between the inner and outer walls of the casing in the polar coordinate system, determine the two-dimensional shape of the asymmetric damage of the casing in the radial direction at the set depth position.

[0120] In some examples, the second acquisition part 804 is configured as:

[0121] According to the magnetic field distribution between the inner and outer walls of the casing in the polar coordinate system, determine the size of the asymmetric damage of the casing in the radial direction at the set depth position and the angle between the asymmetric damage and the eccentric probe.

[0122] It can be understood that in this embodiment, "part" can be part of a circuit, part of a processor, part of a program or software, etc. Of course, it can also be a unit, or a module, or non-modular.

[0123] In addition, the components in this embodiment can be integrated in a processing unit, or each unit can exist physically alone, or two or more units can be integrated in one unit. The above integrated unit can be implemented in the form of hardware or in the form of a software function module.

[0124] When the integrated unit is implemented in the form of a software function module and is not sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this embodiment, in essence, or the part that contributes to the prior art, or all or part of this technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) or a processor to execute all or part of the steps of the method described in this embodiment. The foregoing storage medium includes: various media such as USB flash drives, mobile hard disks, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical discs that can store program codes.

[0125] Therefore, the present embodiment provides a computer storage medium storing a detection program for eddy current diffusion based on a circular array. When the detection program for eddy current diffusion based on a circular array is executed by at least one processor, the method steps of the detection method for eddy current diffusion based on a circular array in the above technical solution are implemented.

[0126] According to the above-described detection device 80 for eddy current diffusion based on a circular array and the computer storage medium, referring to Figure 9 , which shows the specific hardware structure of a computing device 90 capable of implementing the above-described detection device 80 for eddy current diffusion based on a circular array provided by an embodiment of the present invention. The computing device 90 may specifically be a ground chassis or a host computer, etc. The computing device 90 includes: a communication interface 901, a memory 902, and a processor 903; each component is coupled together through a bus system 904. It can be understood that the bus system 904 is used to realize the connection and communication between these components. In addition to the data bus, the bus system 904 also includes a power bus, a control bus, and a status signal bus. However, for the sake of clarity, in Figure 9 all kinds of buses are labeled as the bus system 904. Among them,

[0127] the communication interface 901 is used for receiving and sending signals during the process of receiving and transmitting information with other external network elements;

[0128] the memory 902 is used for storing a computer program that can run on the processor 903;

[0129] the processor 903 is used for performing the following steps when running the computer program:

[0130] According to the circumferential azimuth dimension information of the casing received by the eccentric probes distributed in a circular array, obtain the magnetic field distribution of the non-symmetric damage azimuth - eddy current diffusion time dimension of the casing at different damage degrees at a set depth position;

[0131] Based on the magnetic field distribution of the non-symmetric damage azimuth - eddy current diffusion time dimension of the casing at different damage degrees at a set depth position, determine the first correspondence relationship between the eddy current diffusion time and the circumferential radius of the casing at the set depth position;

[0132] Determine the second correspondence relationship between the circumferential azimuth dimension information of the casing and the circumferential radius of the casing;

[0133] Based on the first correspondence relationship and the second correspondence relationship, obtain the two-dimensional shape of the non-symmetric damage of the casing in the radial direction at the set depth position;

[0134] Obtain the three-dimensional morphology of the asymmetric damage of the casing according to the two-dimensional morphology and circumferential orientation of the asymmetric damage of the casing at multiple different set depth positions in the radial direction.

[0135] It can be understood that the memory 902 in the embodiments of the present invention can be a volatile memory or a non-volatile memory, or can include both volatile and non-volatile memories. Among them, the non-volatile memory can be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory. The volatile memory can be a random access memory (RAM), which is used as an external cache. By way of example but not limitation, many forms of RAM are available, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchlink dynamic random access memory (SLDRAM), and direct rambus random access memory (DRRAM). The memory 902 of the systems and methods described herein is intended to include but not be limited to these and any other suitable types of memory.

[0136] The processor 903 may be an integrated circuit chip with the ability to process signals. In the implementation process, the steps of the above method can be completed by the integrated logic circuit in hardware or the instructions in software form in the processor 903. The above-mentioned processor 903 may be a general-purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components. It can implement or execute the various methods, steps, and logic block diagrams disclosed in the embodiments of the present invention. The general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc. The steps of the method disclosed in combination with the embodiments of the present invention can be directly embodied as being executed and completed by a hardware decoding processor, or executed and completed by a combination of hardware and software modules in the decoding processor. The software module may be located in a mature storage medium in the art such as a random access memory, a flash memory, a read-only memory, a programmable read-only memory, or an electrically erasable programmable memory, a register, etc. This storage medium is located in the memory 902, and the processor 903 reads the information in the memory 902 and combines its hardware to complete the steps of the above method.

[0137] It can be understood that these embodiments described herein can be implemented using hardware, software, firmware, middleware, microcode, or a combination thereof. For hardware implementation, the processing unit can be implemented in one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), field-programmable gate arrays (FPGAs), general-purpose processors, controllers, microcontrollers, microprocessors, other electronic units for performing the functions described in this application, or a combination thereof.

[0138] For software implementation, the technologies described herein can be implemented by modules (such as procedures, functions, etc.) that execute the functions described herein. The software code can be stored in a memory and executed by a processor. The memory can be implemented inside or outside the processor.

[0139] Specifically, when the processor 903 is further configured to run the computer program, it executes the steps of the detection method based on circular array vortex diffusion in the foregoing technical solution, which will not be elaborated here.

[0140] It should be noted that the technical solutions described in the embodiments of the present invention can be arbitrarily combined without conflict.

[0141] As mentioned above, the above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, and all should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A detection method for eddy current diffusion based on a circular array, characterized in that, The detection method includes: Based on the circumferential azimuth dimension information of the casing received by the eccentric probes distributed in a circular array, obtaining the magnetic field distribution of the asymmetric damage azimuth - eddy current diffusion time dimension of the casing at different damage degrees at a set depth position; Based on the magnetic field distribution of the asymmetric damage azimuth - eddy current diffusion time dimension of the casing at different damage degrees at a set depth position, determining the first correspondence between the eddy current diffusion time and the circumferential radius of the casing at the set depth position; Determining the second correspondence between the circumferential azimuth dimension information of the casing and the circumferential radius of the casing; Based on the first correspondence and the second correspondence, obtaining the two - dimensional shape of the asymmetric damage of the casing in the radial direction at the set depth position; According to the two - dimensional shapes and circumferential azimuths of the asymmetric damage of the casing in the radial direction at multiple different set depth positions, obtaining the three - dimensional shape of the asymmetric damage of the casing.

2. The detection method according to claim 1, characterized in that, The step of determining the first correspondence between the eddy current diffusion time and the circumferential radius of the casing at the set depth position based on the magnetic field distribution of the asymmetric damage azimuth - eddy current diffusion time dimension of the casing at different damage degrees at the set depth position includes: According to the magnetic field distribution of the asymmetric damage azimuth - eddy current diffusion time dimension of the casing at different damage degrees at the set depth position, extracting the eddy current diffusion time corresponding to the null in the direction of the damage center; Based on the eddy current diffusion time corresponding to the null in the direction of the damage center, determining the first correspondence between the eddy current diffusion time and the circumferential radius of the casing.

3. The detection method according to claim 2, wherein The step of determining the first correspondence between the eddy current diffusion time and the circumferential radius of the casing based on the eddy current diffusion time corresponding to the null in the direction of the damage center includes: Based on the change trend of the eddy current diffusion time corresponding to the null in the direction of the damage center, obtaining the change trend of the normalized magnetic flux density modulus in the direction of the damage center at different damage degrees at the set depth position; According to the change trend of the normalized magnetic flux density modulus in the direction of the damage center at different damage degrees at the set depth position, obtaining the eddy current diffusion time when the normalized magnetic flux density modulus reaches a peak at different damage degrees at the set depth position; According to the eddy current diffusion time when the normalized magnetic flux density modulus reaches a peak at different damage degrees at the set depth position, determining the first correspondence between the eddy current diffusion time and the circumferential radius of the casing as: （1） Among them, , and are constants.

4. The detection method according to claim 1, wherein The step of determining the second correspondence between the circumferential azimuth dimension information of the casing and the circumferential radius of the casing includes: Setting a plurality of sampling points during the peak time period when the eddy current diffuses to the inner and outer walls of the casing, and obtaining the first reception response of the eccentric probe during the sampling time periods corresponding to the plurality of sampling points as: （2） Among them, P and Q respectively represent the sampling points; K represents the number of GMR receiving sensors included in the eccentric probe; L represents the total number of the sampling points; among them, 1 ≤ P, Q ≤ L and P <Q; Performing a transformation on the first reception response of the eccentric probe during the sampling time periods corresponding to the plurality of sampling points according to Equation (3), and obtaining the second reception response of the eccentric probe in the polar coordinate system; （3） Among them, the ordered pair represents a point in the rectangular coordinate system corresponding to the coordinates in the polar coordinate system, where represents the polar radius, represents the polar angle; when takes P to Q the polar radius and the polar radius respectively represent the inner wall radius r inner and the outer wall radius r outer ; as l and k change, and the signal value of the enclosed area is ; when l takes P to Q , k takes from 1 to K the corresponding polar coordinate region represents the region between the inner and outer walls of the casing; Among them, the transformation relationship formula (3) between the first reception response and the second reception response is used to represent the second correspondence.

5. The detection method according to claim 1, characterized in that Based on the first correspondence relationship and the second correspondence relationship, obtaining the two-dimensional shape of the asymmetric damage of the casing at the set depth position in the radial direction includes: Based on the first correspondence relationship, obtaining the circumferential radius of the casing; wherein, the circumferential radius of the casing is used to characterize the wall thickness at the asymmetric damage of the casing; Based on the second correspondence relationship, converting the magnetic field distribution of the asymmetric damage azimuth - eddy current diffusion time dimension of the casing at different damage degrees at the set depth position into the magnetic field distribution between the inner and outer walls of the casing in the polar coordinate system; According to the magnetic field distribution between the inner and outer walls of the casing in the polar coordinate system, determining the two-dimensional shape of the asymmetric damage of the casing at the set depth position in the radial direction.

6. The detection method according to claim 5, characterized in that The determining the two-dimensional shape of the asymmetric damage of the casing at the set depth position in the radial direction according to the magnetic field distribution between the inner and outer walls of the casing in the polar coordinate system includes: According to the magnetic field distribution between the inner and outer walls of the casing in the polar coordinate system, determining the size of the asymmetric damage of the casing at the set depth position in the radial direction and the angle between the asymmetric damage and the eccentric probe.

7. A detection device for eddy current diffusion based on a circular array, characterized in that, The detection device includes: a first acquisition part, a first determination part, a second determination part, a second acquisition part, and a third acquisition part; wherein, The first acquisition part is configured to acquire the magnetic field distribution of the asymmetric damage azimuth - eddy current diffusion time dimension of the casing at different damage degrees at the set depth position according to the circumferential azimuth dimension information of the casing received by the eccentric probes distributed in a circular array; The first determination part is configured to determine the first correspondence relationship between the eddy current diffusion time and the circumferential radius of the casing based on the magnetic field distribution of the asymmetric damage azimuth - eddy current diffusion time dimension of the casing at different damage degrees at the set depth position; The second determination part is configured to determine the second correspondence relationship between the circumferential azimuth dimension information of the casing and the circumferential radius of the casing; The second acquisition part is configured to obtain the two-dimensional shape of the asymmetric damage of the casing at the set depth position in the radial direction based on the first correspondence relationship and the second correspondence relationship; The third acquisition part is configured to obtain the three-dimensional shape of the asymmetric damage of the casing according to the two-dimensional shapes and circumferential azimuths of the asymmetric damage of the casing at multiple different set depth positions in the radial direction.

8. The detection device according to claim 7, wherein, The first determination part is configured to: According to the magnetic field distribution of the asymmetric damage azimuth - eddy current diffusion time dimension of the casing at different damage degrees at the set depth position, extracting the eddy current diffusion time corresponding to the null in the direction of the damage center; Based on the eddy current diffusion time corresponding to the null in the direction of the damage center, determining the first correspondence relationship between the eddy current diffusion time and the circumferential radius of the casing.

9. The detection device according to claim 8, characterized in that, The first determination part is further configured to: Based on the change trend of the eddy current diffusion time corresponding to the null in the direction of the damage center, obtaining the change trend of the normalized magnetic flux density modulus in the direction of the damage center at different degrees of damage at the set depth position; According to the change trend of the modulus of the normalized magnetic flux density in the direction where the damage center is located at different degrees of damage at the set depth position, obtain the eddy current diffusion time when the modulus of the normalized magnetic flux density peaks at different degrees of damage at the set depth position; According to the eddy current diffusion time when the modulus of the normalized magnetic flux density peaks at different degrees of damage at the set depth position, determine that the first corresponding relationship between the eddy current diffusion time and the circumferential radius of the casing is: （1） Among them, , and are constants.

10. A medium, characterized in that, The medium stores a detection program for eddy current diffusion based on a circular array. When the detection program for eddy current diffusion based on a circular array is executed by at least one processor, the steps of the detection method for eddy current diffusion based on a circular array described in any one of claims 1 to 6 are implemented.

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