A detection method, device and system for asymmetric damage of a casing

Abstract

An embodiment of the present invention discloses a detection method, device and system for asymmetric damage of a casing; the detection device includes: a plurality of detection probes; wherein each of the detection probes includes a magnetic core, a transmitting coil wound around the outer periphery of the magnetic core, and a plurality of giant magnetoresistive GMR sensors wound around the longitudinal center position of the transmitting coil and uniformly distributed in a circular array; wherein the plurality of detection probes are coaxially distributed in sequence along a set detection depth, and each of the detection probes rotates along a common rotation axis in the same direction at a set angle, so that all the GMR sensors form a circular array and are uniformly distributed in the 360° direction around the wellbore, so as to determine the azimuth and three-dimensional shape of the asymmetric damage of the casing according to the received response of the synthesized circular array.

Description

Technical Field

[0001] Embodiments of the present invention relate to the technical field of oil and gas field equipment detection, and in particular, to a detection method, device and system for asymmetric damage of casing pipes. Background Art

[0002] As the service life of casing pipes in oil and gas fields at home and abroad increases, coupled with factors such as formation stress and chemical corrosion, most oil and gas casing pipes have different degrees and types of damage, such as diameter reduction, deformation, corrosion, and rupture. These damages will directly affect the production and service life of oil and gas wells. Through the damage detection of casing pipes, the changes and damage conditions of the wellbore structure of oil and gas wells can be discovered in time, which is of great significance for the prevention and maintenance of casing pipes. Therefore, the damage detection of casing pipes has become a crucial task in the process of oil and gas field development. However, affected by the different formation pressures around the casing pipes, these damages usually occur asymmetrically, which further increases the difficulty and complexity of casing pipe damage detection.

[0003] Existing casing pipe damage detection technologies mainly include multi-arm caliper, acoustic logging, downhole TV, electromagnetic flaw detection and other detection technologies; among them, the multi-arm caliper uses mechanical detection arms to detect the diameter or radius inside the casing pipe, and judges the damage such as distortion, misalignment, holes, cracks or inner wall corrosion of the casing pipe through the measured diameter or radius; acoustic logging uses ultrasonic waves to monitor the reflection characteristics of the damaged part of the casing pipe, and judges the damage condition of the casing pipe by the amplitude, time and frequency changes of the echo picked up by the transducer; downhole TV uses a TV camera to scan along the wellbore core, and monitors the changes in the well through the TV display screen on the ground, so as to directly display the damage condition of the inner wall of the downhole tubing or casing pipe; electromagnetic flaw detection is based on the principle of non-contact pulsed eddy current detection. Utilizing the characteristic that the electrical conductivity of the metal casing pipe is greater than that of the surrounding formation medium, the damage defects of the tubing or casing pipe can be measured by one trip downhole. The mechanical structure is simple, easy to disassemble, convenient to repair, can be cascaded, and can also be connected with a multi-arm caliper, etc., and can also be used independently. Among the above methods, the non-destructive testing technology based on pulsed eddy current can obtain more information about the measured medium in one detection due to its wide-spectrum excitation method and fast measurement characteristics. It can not only greatly simplify the complexity of the instrument, but also obtain good detection performance and accuracy, and occupies a certain advantage in the field of downhole casing pipe damage detection.

[0004] However, existing electromagnetic flaw detection technologies quantify the wall thickness of metal casing using the diffusion time constant of eddy current to extract information containing the characteristics of downhole casing damage from the received signals. Currently, the existing methods use the centers of the probes to coincide with the wellbore axis, and their detection responses contain information about 360° around the casing circumference. Based on this information, only the damage situation of the casing can be qualitatively evaluated, and the asymmetric damage of the local part of the casing cannot be reflected, nor can the azimuth, size, and shape of the asymmetric damage be accurately identified. Moreover, when there are multiple different types of asymmetric damage on the casing, it is also difficult to effectively judge the specific shape of the damage using traditional electromagnetic flaw detection methods. Summary of the Invention

[0005] In view of this, embodiments of the present invention are expected to provide a detection method, device, and system for asymmetric damage of casing, which can detect the azimuth and three-dimensional shape of asymmetric damage in the casing.

[0006] The technical solutions of the embodiments of the present invention are implemented as follows:

[0007] In a first aspect, an embodiment of the present invention provides a detection device for asymmetric damage of casing. The detection device includes: a plurality of detection probes; wherein, each of the detection probes includes a magnetic core, a transmitting coil wound around the outer circumference of the magnetic core, and a plurality of giant magnetoresistive GMR sensors wound around the longitudinal center position of the transmitting coil and uniformly distributed in a circular array form; wherein,

[0008] The plurality of detection probes are coaxially distributed in sequence along a set detection depth, and each of the detection probes rotates along a common rotation axis in the same direction at a set angle, so that all the GMR sensors form a circular array and are uniformly distributed in the 360° direction around the well circumference, to determine the azimuth and three-dimensional shape of the asymmetric damage of the casing according to the received response of the synthesized circular array.

[0009] In a second aspect, an embodiment of the present invention provides a detection system for asymmetric damage of casing. The detection system includes:

[0010] The detection device according to the first aspect;

[0011] A logging winch, the logging winch includes a single-core cable for lowering the detection device into the casing;

[0012] An upper computer, the upper computer is connected to the logging winch through the single-core cable; the upper computer 32 is configured to send the required transmitting current to each detection probe in the detection device; and, receive the measurement signals sent by a plurality of GMR sensors in the detection device; and, determine the azimuth and three-dimensional shape of the non-damage of the casing according to the measurement signals.

[0013] Thirdly, an embodiment of the present invention provides a method for detecting asymmetric damage of a casing. The detection method can be applied to the detection system for asymmetric damage of the casing described in the second aspect. The detection method includes:

[0014] Obtaining the magnetic field intensity received by each detection probe according to Equation (1):

[0015]

[0016] where t and z k are respectively the sampling time and the detection depth where the k-th detection probe is located; M represents the number of GMR sensors arranged on each detection probe, and H k (t, z k ) ∈ M×1; H (k-1)M+m (t, z k ) represents the magnetic field intensity received by the m-th GMR sensor arranged on the k-th detection probe; 1 ≤ m ≤ M;

[0017] Obtaining the reception response of the circular array synthesized by multiple GMR sensors according to the magnetic field intensity received by each detection probe;

[0018] Determining the non-damaged orientation and three-dimensional shape of the casing according to the reception response.

[0019] An embodiment of the present invention provides a method, device and system for detecting asymmetric damage of a casing; the detection device coaxially distributes multiple detection probes along a set detection depth in sequence, and each detection probe rotates around a common rotation axis in the same direction at a set angle, so that all the GMR sensors synthesize a circular array and are evenly distributed in the 360° direction around the wellbore, so as to introduce an azimuth dimension measurement signal for the detection of asymmetric damage on the casing through the synthesized circular array, so as to improve the circumferential azimuth resolution of the detection of asymmetric damage of the casing. At the same time, the three-dimensional shape detection of the asymmetric damage of the casing is realized by analyzing the reception response of the synthesized circular array. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a schematic structural diagram of a detection device for asymmetric damage of a casing provided by an embodiment of the present invention;

[0021] Figure 2 is another schematic structural diagram of a detection device for asymmetric damage of a casing provided by an embodiment of the present invention;

[0022] Figure 3 is a schematic composition diagram of a detection system for asymmetric damage of a casing provided by an embodiment of the present invention;

[0023] Figure 4A schematic diagram of another system for detecting asymmetric damage of casing provided by an embodiment of the present invention;

[0024] Figure 5 A schematic diagram of a three-dimensional data structure corresponding to a synthetic circular array receiving response provided in an embodiment of the present invention;

[0025] Figure 6 A schematic diagram of the detection results of asymmetric hole damage morphology in a casing provided by an embodiment of the present invention;

[0026] Figure 7 A schematic flow chart of a method for detecting asymmetric damage of a casing provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0028] Before elaborating on the embodiments of the present invention in detail, the structure of the conventional casing logging instrument is introduced by taking a conventional casing logging instrument with an outer diameter of 43 mm as an example. Considering the pressure bearing requirements, it is assumed that the wall thickness of the outer protective tube of the logging instrument is 5.5 mm, and the actual inner diameter of the logging instrument is 32 mm. Therefore, in a limited space, in order to improve the circumferential azimuth resolution of asymmetric damage detection in the casing, it is necessary to reduce the size of the receiving sensor as much as possible. Therefore, based on the influencing factors such as size, sensitivity and high temperature application environment, the embodiment of the present invention selects a giant magnetoresistance (Giant Magneto Resistive, GMR) sensor as the receiving sensor, and the specific model is AAH002-02. Of course, in the specific implementation process, other models of GMR sensors can also be selected as receiving sensors according to actual needs. The size of the GMR sensor is 6.2mm×5mm×1.3mm, but due to the influence of factors such as the base, the pad and the line, a maximum of 10 of the above-mentioned GMR sensors can be set in the logging instrument with an inner diameter of 32mm, that is, each of the above-mentioned GMR sensors can only detect damage information in the casing with an azimuth size of 36°. However, in the prior art, it is difficult to design a receiving sensor in a ring array that can detect asymmetric damage conditions of casing with high precision.

[0029] In view of this, see Figure 1 , which shows a detection device 1 for asymmetric casing damage provided by an embodiment of the present invention, the detection device 1 may include: a plurality of detection probes 11; wherein each of the detection probes 11 includes a magnetic core 111, a transmitting coil 112 wound around the outer periphery of the magnetic core 111, and a plurality of GMR sensors 113 wound around the longitudinal center of the transmitting coil 112 and evenly distributed in a circular array; wherein,

[0030] A plurality of the detection probes 11 are coaxially distributed in sequence along a set detection depth, and each of the detection probes 11 rotates around a common rotation axis in the same direction by a set angle, so that all the GMR sensors 113 form a circular array and are evenly distributed in the 360° direction around the wellbore, so as to determine the azimuth and three-dimensional shape of the asymmetric damage of the casing according to the received response of the synthesized circular array.

[0031] For Figure 1 For the detection device 1 shown, by coaxially distributing a plurality of detection probes in sequence along a set detection depth, and each detection probe rotates around a common rotation axis in the same direction by a set angle, so that all the GMR sensors form a circular array and are evenly distributed in the 360° direction around the wellbore, so as to introduce an azimuth dimension measurement signal for the detection of asymmetric damage on the casing through the synthesized circular array, so as to improve the circumferential azimuth resolution of the detection of asymmetric damage of the casing. At the same time, the three-dimensional shape detection of the asymmetric damage of the casing is realized by analyzing the received response of the synthesized circular array.

[0032] It can be understood that in the embodiment of the present invention, the transmitting coil 112 is used to transmit a transient electromagnetic excitation signal to induce a secondary eddy current field in the casing; the GMR sensor 113 is used to detect and receive the magnetic field information of the secondary eddy current fields in different directions in the casing during the off-interval of the transient electromagnetic excitation signal.

[0033] It should be noted that Figure 1 only shows a schematic diagram of the detection device 1 including 4 detection probes 11, and each detection probe 11 includes 8 GMR sensors 113. However, in the specific implementation process, the specific numbers of the detection probes 11 and the GMR sensors 113 can be determined according to the actual situation. It should be noted that in the embodiment of the present invention, the radius of each detection probe is 1.5 cm, and the 8 GMR sensors wound on each detection probe 11 are evenly distributed at the longitudinal center position of the corresponding detection probe 11.

[0034] It can be understood that for Figure 1 the detection device 1 shown, when a plurality of detection probes 11 are provided in the detection device 1 and a set detection depth spacing is maintained between the detection probes 11, such a setting mode can not only avoid mutual interference between the detection probes 11, but also be able to arrange a main control cable, a transmitting circuit, a signal acquisition circuit, etc. in the interval space therebetween.

[0035] In addition, specifically, taking Figure 1Taking the 4 detection probes 11 shown as an example, and each detection probe 11 includes 8 GMR sensors 113. In the specific implementation process, taking the detection depth and azimuth of the detection probe 11-1 as a reference, the rotation angle difference between two adjacent detection probes 11 is 360° / 32 = 11.25°. That is to say, the detection probes 11-2, 11-3, and 11-4 rotate 11.25°, 22.5°, and 33.75° respectively relative to the detection probe 11-1 around the common rotation axis X.

[0036] On the other hand, in order to minimize the interference between multiple detection probes 11 as much as possible, in the embodiments of the present invention, the detection depth difference Δz between two adjacent detection probes 11 is set to 40 cm. By lowering multiple detection probes 11 into the oil and gas well successively along the set detection depth, so that the depths z, 2z, and 3z at which the detection probes 11-2, 11-3, and 11-4 receive magnetic field signals can be compensated to the detection depth where the longitudinal center of the detection probe 11-1 is located, and longitudinal projection is performed, so that the above 32 GMR sensors 113 divide the 360° around the well into 32 equal detection regions, so that Figure 1 the 32 GMR sensors shown in (such as Figure 1 the black circles in the right figure) can form a synthetic circular array with uniform distribution and an interval of 11.25°. The above GMR sensors 113 distributed in a uniform synthetic circular array can introduce magnetic field information in different directions around the well for the detection of asymmetric damage of the casing, thereby improving the circumferential azimuth resolution of the detection of asymmetric damage of the casing. It should be noted that by analyzing the magnetic field information received by the above synthetic circular array, the three-dimensional shape detection of the asymmetric damage of the casing can be realized.

[0037] It should be noted that in order to ensure the matching of the detection signals of the synthetic circular array, the emission resistances, the number of turns of the emission coils 112, and the emission signals of the above multiple detection probes 11 need to be kept highly consistent.

[0038] For Figure 1 the detection device 1 shown, in some possible implementation manners, as Figure 2 shown, the detection device 1 further includes: a pony head 12 for connecting the detection device 1 and a single-core cable.

[0039] For Figure 1 the detection device 1 shown, in some possible implementation manners, as Figure 2 shown, the detection device 1 further includes: an upper centralizer 13 and a lower centralizer 14 located at both ends of the detection device 1 to ensure that the detection device 1 always remains at the axis position of the wellbore underground.

[0040] Combining the above two possible implementation manners, specifically,Figure 2 Fig. Figure 2 shows the specific form when the detection device 1 is implemented. The horsehead 12 is used to connect the detection device 1 and the single-core cable, which can ensure the quick disassembly and communication connection of the detection device 1, so as to facilitate the smooth progress of the detection work. The upper and lower centralizers 13 and 14 are respectively located at the upper and lower ends of the detection device 1. Centralizers of different sizes can be replaced according to the wellbore size, so that the detection device 1 can always be kept at the axial position of the wellbore during the detection process, that is, the detection probe 11 is always kept at the axial position of the wellbore, making the transmitting coil 112 and the GMR sensor 113 in the detection probe 11 concentric circles with the wellbore, casing, and cement layer, avoiding eccentricity and shaking of the GMR sensor 113 during the lowering and lifting processes of the detection, thereby bringing detection errors.

[0041] Based on the same inventive concept as the foregoing technical solution, refer to Figure 3 , which shows a detection system 3 for asymmetric damage of a casing provided by an embodiment of the present invention. The detection system 3 includes:

[0042] The detection device 1 according to the foregoing technical solution;

[0043] A logging winch 31, the logging winch 31 includes a single-core cable 311 for lowering the detection device 1 into the casing;

[0044] An upper computer 32, the upper computer 32 is connected to the logging winch 31 through the single-core cable 311; the upper computer 32 is configured to send the required transmitting current to each detection probe 11 in the detection device 1; and, receive the measurement signals sent by a plurality of GMR sensors 113 in the detection device 1; and, determine the orientation and three-dimensional shape of the non-damage of the casing according to the measurement signals.

[0045] In the specific implementation process, it should be noted that the upper computer 32 may include a data transmission part, a data processing part, a depth calculation part, and an image display part. The depth calculation part can monitor the detection depth information of the downhole instrument in real time, estimate the casing structure at the detection depth where the current detection device 1 is located, calculate the required transmitting current for each transmitting coil 112 in the detection device 1 according to the current casing structure, and send it to the detection device 1. At the same time, the data transmission part can receive and save the detection data uploaded by the detection device 1, and the data processing part is used to judge whether there is asymmetric damage in the casing according to the casing structures at all detection depths and the measurement signals received by each GMR sensor 113, and if there is damage, quantify the damage situation. The casing structure, real-time damage detection results, and historical detection results can all be intuitively displayed through the image display part.

[0046] For the detection system 3, the design of synthesizing a uniformly distributed synthetic circular array through multiple GMR sensors 113 can introduce azimuth dimension information for the detection of asymmetric damage to downhole casings, so as to improve the circumferential resolution of casing asymmetric damage detection. At the same time, by using the upper computer 32 to analyze and stack images of the azimuth-time dimension detection data of the circular array synthesized by multiple GMR sensors at different detection depths, the azimuth and three-dimensional shape of the asymmetric damage of the casing can be determined.

[0047] In addition, in the specific implementation process, as Figure 3 shown, the detection device 1 can be connected to the logging winch 31 and the upper computer 32 in sequence through a single-core cable 311. The logging winch 32 controls the detection device 1 to be lifted and lowered in the well at the required speed. The single-core cable 311 is used to transport the detection device 1, supply power to the detection device 1, transmit the emission current information of each emission coil 113 calculated by the upper computer 32 to the detection device 1, and transmit the measurement signals collected by each GMR sensor 113 to the upper computer 32. In most conventional implementation processes, as Figure 4 shown, in the well, the detection device 1 is, from the inside to the outside, a casing, a cement layer, and a formation in sequence.

[0048] For Figure 3 the detection system 3 shown, in some possible implementation manners, the upper computer 32 is configured as:

[0049] Obtain the magnetic field intensity received by each detection probe according to Equation (1):

[0050]

[0051] where t and z k are the sampling time and the detection depth where the kth detection probe is located, respectively; M represents the number of GMR sensors provided on each detection probe, and H k (t, z k ) ∈ M×1; H (k-1)M+m (t, z k ) represents the magnetic field intensity received by the mth GMR sensor provided on the kth detection probe; 1 ≤ m ≤ M;

[0052] Obtain the reception response of the synthetic circular array of multiple GMR sensors according to the magnetic field intensity received by each detection probe;

[0053] Determine the azimuth and three-dimensional shape of the non-damaged part of the casing according to the reception response.

[0054] It should be noted that in the specific implementation process, the magnetic field intensity H corresponding to each GMR sensor 113 is measured by using the GMR sensor 113 (k-1)M+m (t, zk )。

[0055] For Figure 3 the detection system 3 shown, in some possible implementation manners, the host computer 32 is configured as follows:

[0056] Based on the magnetic field intensity received by each detection probe, the received response of the synthetic circular array without depth compensation for detection is obtained according to Equation (1) as shown in Equation (2):

[0057]

[0058] where K represents the number of detection probes; 1 ≤ k ≤ K;

[0059] The detection depths at which the GMR sensors on the second to the Kth detection probes receive measurement signals are all compensated to the detection depth where the first detection probe is located, and the received response of the synthetic circular array after depth compensation for detection is obtained according to the detection depth difference Δz between the detection probes as shown in Equation (3):

[0060]

[0061] When each GMR sensor samples at equal intervals and the sampling length is L, the received response of the synthetic circular array at the sampling times from t1 to t L is obtained according to Equation (4):

[0062]

[0063] It should be noted that in the specific implementation process, first, without considering depth compensation for detection, a synthetic circular array with uniformly distributed multiple GMR sensors is synthesized, and the received response corresponding to this synthetic circular array is obtained according to Equation (2); on this basis, considering the distribution of each detection probe in the downhole detection system 3, the detection depths at which the GMR sensors on the second to the Kth detection probes receive measurement signals are all compensated to the detection depth where the first detection probe is located. The received response of the synthetic circular array after compensating the detection depth is as shown in Equation (3):

[0064]

[0065] It can be understood that it is equivalent to using KM GMR sensors on one detection probe to simultaneously receive measurement signals, so that the angular resolution of the detection system 3 reaches 360° / KM, for example, 360° / 32 = 11.25° in the foregoing technical solution.

[0066] In addition, in the embodiments of the present invention, when each GMR sensor can sample at equal intervals and the sampling length is L, then from t1 to t L The received response of the synthesized circular array at the sampling moment can be expressed as:

[0067]

[0068] For Figure 3 In the detection system 3 shown, in some possible implementation manners, the host computer 32 is configured as:

[0069] Considering the mobility of the detection probe during the detection process, when the moving detection depth of the detection probe along the well axis direction is from z1 to z D At this time, based on Equation (4), the received responses of the GMR sensors at all detection depths are stacked as shown in Equation (5):

[0070]

[0071] Based on the received response shown in Equation (5), the host computer uses an image to display the azimuth and three-dimensional shape of the asymmetric damage of the casing.

[0072] It should be noted that Equations (2) to (4) are all the received responses obtained when the detection probe is stationary. However, in the actual detection process, the detection probe will move up and down. Therefore, in the specific implementation process, the received response obtained by Equation (4) needs to be stacked at all detection depths to obtain the received response of the synthesized circular array at all detection depths.

[0073] As can be seen from Equation (5), after multiple GMR sensors at all detection depths are synthesized into a uniformly distributed synthesized circular array, its received response corresponds to a three-dimensional data structure. Therefore, the effect of a cylindrical array can be achieved during the detection data processing, specifically as Figure 5 shown, where the three coordinate axes respectively represent the received responses of the GMR sensors in KM different azimuths, L sampling moments, and D detection depths.

[0074] Specifically, as Figure 5As shown, the KM×L independent detection curves after detection depth compensation correspond to D detection depths in total. Each detection curve corresponds to the received response shown in Equation (4) and can be used to detect the two-dimensional shape of the asymmetric damage of the downhole casing. For example, taking the received response of the synthetic circular array at different sampling times at a certain detection depth as an example, the coordinate axis L can be used to analyze the radial penetration depth of the asymmetric damage of the casing; the coordinate axis KM can be used to analyze the size and angular range of the symmetric damage of the casing. It should be noted that the larger K and M are, the higher the theoretically achievable angular resolution is. However, the larger K is, the longer the length of the downhole detection system 3 is, which is not conducive to detection depth compensation. At the same time, the number of M is related to the inner diameter of the logging tool and the size of the GMR sensor. That is to say, as long as the inner diameter of the logging tool and the size of the GMR sensor are determined, the number of M is also determined. Therefore, in the specific implementation process, K and M need to be optimized according to the actual situation.

[0075] On the other hand, for example, if there is a hole-shaped damage with a radius of 1 cm on the casing and the hole is located on one side of the casing, the above detection system 3 is used to detect the hole, and the two-dimensional detection results at multiple detection depths are stacked, specifically as Figure 6 shown, as Figure 6 it can be seen the three-dimensional shape of the hole and the detection depth of the hole damage is 40 cm. It should be noted that in the specific implementation process, the direction where the hole is located is marked as the 0-degree direction during the image display.

[0076] Based on the same inventive concept as the technical solution described in the foregoing embodiments, refer to Figure 7 , which shows a method for detecting asymmetric damage of a casing provided by an embodiment of the present invention. The detection method is applied to a detection system for asymmetric damage of a casing described in the foregoing technical solution. The detection method includes:

[0077] S701. Obtain the magnetic field intensity received by each detection probe according to Equation (1):

[0078]

[0079] where t and z k are the sampling time and the detection depth at which the kth detection probe is located, respectively; M represents the number of GMR sensors provided on each detection probe, and H k (t, z k ) ∈ M×1; H (k-1)M+m (t, z k ) represents the magnetic field intensity received by the mth GMR sensor provided on the kth detection probe; 1 ≤ m ≤ M;

[0080] S702. Obtain the reception response of the synthetic circular array of multiple GMR sensors according to the magnetic field intensity received by each of the detection probes;

[0081] S703. Determine the non-damaged orientation and three-dimensional shape of the casing according to the reception response.

[0082] Understandably, Figure 7 The technical solution shown can be implemented by the detection system for asymmetric damage of the casing described in the foregoing embodiments. Therefore, the detection method for asymmetric damage of the casing provided in the embodiments of the present invention has the same technical advantages and effects as the detection system for asymmetric damage of the casing described in the foregoing embodiments, and the embodiments of the present invention will not be elaborated.

[0083] For Figure 7 The technical solution shown, in some possible implementation manners, the obtaining the reception response of the synthetic circular array of multiple GMR sensors according to the magnetic field intensity received by each of the detection probes includes:

[0084] According to the magnetic field intensity received by each of the detection probes, obtain the reception response of the synthetic circular array without detection depth compensation as shown in Equation (2) based on Equation (1):

[0085]

[0086] where K represents the number of the detection probes; 1 ≤ k ≤ K;

[0087] Compensate the detection depths of the GMR sensors receiving measurement signals on the 2nd to the Kth detection probes to the detection depth where the 1st detection probe is located, and obtain the reception response of the synthetic circular array after detection depth compensation as shown in Equation (3) according to the detection depth difference Δz between the detection probes:

[0088]

[0089] When each GMR sensor samples at equal intervals and the sampling length is L, obtain the reception response of the synthetic circular array at the sampling times from t1 to t according to Equation (4): L Sampling time:

[0090]

[0091] For Figure 7 The technical solution shown, in some possible implementation manners, the determining the non-damaged orientation and three-dimensional shape of the casing according to the reception response includes:

[0092] Considering the mobility of the detection probe during the detection process, when the moving detection depth of the detection probe along the well axis direction is from z1 to z D At this time, based on Equation (4), the received responses of the GMR sensors at all detection depths are stacked as shown in Equation (5):

[0093]

[0094] Based on the received response shown in Equation (5), the upper computer image is used to display the azimuth and three-dimensional shape of the asymmetric damage of the casing.

[0095] It should be noted that: among the technical solutions described in the embodiments of the present invention, they can be arbitrarily combined without conflict.

[0096] 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 within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all 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 device for asymmetric damage of a casing, characterized in that The detection device includes: a plurality of detection probes; wherein each of the detection probes includes a magnetic core, a transmitting coil wound around the outer periphery of the magnetic core, and a plurality of giant magnetoresistive GMR sensors wound around the longitudinal center position of the transmitting coil and uniformly distributed in a circular array form; wherein, The plurality of detection probes are coaxially distributed in sequence along a set detection depth, and each detection probe rotates along a common rotation axis in the same direction by a set angle, so that all the GMR sensors form a circular array and are uniformly distributed in the 360° direction around the wellbore, to determine the azimuth and three-dimensional shape of the non-symmetric damage of the casing according to the received response of the synthesized circular array. Wherein, the number of the detection probes is four.

2. The detection device according to claim 1, wherein The detection device further includes: a tool joint, which is used for connecting the detection device and a single-core cable.

3. The detection device according to claim 1, characterized in that, The detection device further includes: an upper centralizer and a lower centralizer located at both ends of the detection device, so as to ensure that the detection device always remains at the axial position of the wellbore in the well.

4. A detection system for asymmetric damage of a casing, characterized in that, The detection system includes: The detection device according to any one of claims 1 to 3; A logging winch, the logging winch includes a single-core cable for lowering the detection device into the casing; An upper computer, the upper computer is connected to the logging winch through the single-core cable; the upper computer is configured to send the required transmitting current to each detection probe in the detection device; and, receive the measurement signals sent by a plurality of GMR sensors in the detection device; and, determine the azimuth and three-dimensional shape of the non-damage of the casing according to the measurement signals.

5. The detection system according to claim 4, characterized in that, The upper computer, configured as: Obtain the magnetic field intensity received by each detection probe according to formula (1): （1）； Among them, t and z k are the sampling time and the detection depth where the k th detection probe is located, respectively; M represents the number of GMR sensors provided on each of the detection probes, ; represents the magnetic field intensity received by the k th GMR sensor provided on the m th detection probe; ; Obtain the received response of the synthesized circular array of a plurality of the GMR sensors according to the magnetic field intensity received by each detection probe; Determine the azimuth and three-dimensional shape of the non-damage of the casing according to the received response.

6. The detection system according to claim 5, characterized in that, The upper computer, configured as: Based on the magnetic field intensity received by each detection probe, obtain the received response of the synthesized circular array without depth compensation for detection as shown in formula (2) according to formula (1): （2） Among them, K represents the number of the detection probes; ; Compensate the detection depths at which the GMR sensors on the second to the K th detection probes receive measurement signals to the detection depth of the first detection probe, and obtain the received response of the synthetic circular array after detection depth compensation according to the detection depth differences between the detection probes as shown in Equation (3): ​ （3） When each of the GMR sensors samples at equal intervals and the sampling length is L at this time, the received response of the synthesized circular array at sampling times from 1 to t 1 to t L is obtained according to Equation (4): （4）。 7. The detection system according to claim 6, characterized in that, The upper computer, configured as: Considering the mobility of the detection probe during the detection process, when the moving detection depth of the detection probe along the well axis direction is z 1 to z D , the received responses of the GMR sensors at all detection depths are stacked based on Equation (4) as shown in Equation (5): （5）； Based on the received response shown in formula (5), use the upper computer to image and display the azimuth and three-dimensional shape of the non-symmetric damage of the casing.

8. A detection method for asymmetric damage of a casing, characterized in that, The detection method can be applied to the detection system for non-symmetric damage of the casing according to any one of claims 4 to 7, and the detection method includes: Obtain the magnetic field intensity received by each detection probe according to formula (1): （1）； Among them, t and z k are the sampling time and the detection depth where the k th detection probe is located, respectively; M represents the number of GMR sensors provided on each of the detection probes, ; represents the magnetic field intensity received by the k th GMR sensor provided on the m th detection probe; ; Obtain the received response of the synthesized circular array of a plurality of the GMR sensors according to the magnetic field intensity received by each detection probe; Determine the azimuth and three-dimensional shape of the non-damage of the casing according to the received response.

9. The detection method according to claim 8, wherein The obtaining the received response of the synthesized circular array of a plurality of the GMR sensors according to the magnetic field intensity received by each detection probe includes: Based on the magnetic field intensity received by each detection probe, obtain the received response of the synthesized circular array without depth compensation for detection as shown in formula (2) according to formula (1): （2） Among them, K represents the number of the detection probes; ; Compensate the detection depths at which the GMR sensors on the second to the K th detection probes receive measurement signals to the detection depth where the first detection probe is located, and obtain the received response of the synthetic circular array after detection depth compensation according to the detection depth differences between the detection probes as shown in Equation (3): ​ （3） When each of the GMR sensors samples at equal intervals and the sampling length is L at this time, the received response of the synthesized circular array at the sampling moments from 1 to t 1 to t L is obtained according to Equation (4): （4）。 10. The detection method according to claim 9, characterized in that, The determining the non-damage state of the casing according to the magnetic field intensity includes: Determining the non-damaged orientation and three-dimensional shape of the casing according to the received response includes: Considering the mobility of the detection probe during the detection process, when the detection depth of the movement of the detection probe along the well axis direction is z 1 to z D , the received responses of the GMR sensors at all detection depths obtained by stacking based on Equation (4) are as shown in Equation (5): （5）； Using the host computer image to display the orientation and three-dimensional shape of the asymmetric damage of the casing based on the received response shown in Equation (5).

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