A device and method for gradient-enhanced saturation magnetization internal detection of oil and gas pipelines

Abstract

The present invention discloses a device and method for gradient-enhanced saturation magnetization internal detection of oil and gas pipelines, wherein the method comprises: the pipe section excitation device comprises: an annular rigid skeleton, a first pipe section magnetization magnet, a second pipe section magnetization magnet, a first pipe section steel brush and a second pipe section steel brush; the first pipe section magnetization magnet and the second pipe section magnetization magnet are respectively sleeved on the outer side wall of the annular rigid skeleton; the first pipe section steel brush is sleeved on the outer side wall of the first pipe section magnetization magnet, and the second pipe section steel brush is sleeved on the outer side wall of the second pipe section magnetization magnet; a plurality of the probe local excitation devices comprise a gradient-enhanced magnetization probe and a probe bracket, and the gradient-enhanced magnetization probe is arranged on the rigid skeleton through a circumferential array of the probe bracket. The present invention can implement precise saturation magnetization on the pipeline area covered by the probe to save magnetic field resources, thereby realizing lightweight internal pipeline defect detection.

Description

Technical Field

[0001] The present invention relates to the technical field of oil and gas pipeline internal detection, and in particular to an oil and gas pipeline gradient enhanced saturation magnetization internal detection device and method. Background Art

[0002] During the long-term use of oil and gas pipelines, cracks, corrosion, and wear and tear caused by natural aging, soil settlement, and rockfall may lead to oil and gas leakage, which in turn may cause serious safety accidents. Therefore, regular monitoring and safety assessment of pipelines are extremely important for the safe operation of pipelines.

[0003] At present, pipeline internal detection technology is one of the important means to perceive the pipeline status and maintain safety, including magnetic flux leakage detection technology, ultrasonic detection technology and eddy current detection technology. The internal detector is a detection instrument that integrates detection, information collection and processing functions, and is mainly used for comprehensive detection of oil and gas pipeline defects.

[0004] Traditional magnetic flux leakage detection is a relatively mature internal detection technology with the advantages of high sensitivity, no need for coupling agent and strong anti-interference ability. However, the traditional magnetic flux leakage detection device applies saturation magnetization to a section of the pipeline, resulting in a waste of magnetic field resources. At the same time, the magnetic flux leakage detection device has a large volume, weight and magnetic attraction, and the medium in the low-pressure pipeline is difficult to drive the magnetic flux leakage detection device, resulting in the traditional magnetic flux leakage detection device being unsuitable for medium and low-pressure pipelines.

[0005] In addition, the magnetic flux leakage detection probe supports the inner wall of the pipeline through a flexible mechanical structure. When the magnetic flux leakage detection device passes through the weld and valve, the magnetic flux leakage detection device vibrates significantly, causing the magnetic flux leakage detection probe to lift off, resulting in a significant reduction in the quality of the probe's detection signal. Therefore, the traditional magnetic flux leakage detection device has obvious deficiencies in its ability to detect defects in medium and low pressure pipelines.

[0006] This section is intended to provide a background or context to the embodiments of the invention recited in the claims. No admission is made that the description herein is prior art by inclusion in this section. Summary of the invention

[0007] The embodiment of the present invention provides an oil and gas pipeline gradient enhanced saturation magnetization internal detection device and method, which are used to perform accurate saturation magnetization on the pipeline area covered by the probe to save magnetic field resources, thereby realizing lightweight pipeline internal defect detection.

[0008] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0009] In a first aspect, an embodiment of the present invention provides a gradient-enhanced saturation magnetization internal detection device for oil and gas pipelines, which is used to perform accurate saturation magnetization on the pipeline area covered by the probe, so as to save magnetic field resources and reduce the volume and weight of the pipe section excitation device, thereby realizing lightweight internal defect detection of the pipeline, the device comprising: a pipe section excitation device and a plurality of probe local excitation devices;

[0010] The pipe section excitation device comprises: an annular rigid frame, a first pipe section magnetizing magnet, a second pipe section magnetizing magnet, a first pipe section steel brush and a second pipe section steel brush; the first pipe section magnetizing magnet, the second pipe section magnetizing magnet, the first pipe section steel brush and the second pipe section steel brush are all annular structures; the first pipe section magnetizing magnet and the second pipe section magnetizing magnet are respectively sleeved on the outer side wall of the annular rigid frame, and the polarity of the first pipe section magnetizing magnet is opposite to that of the second pipe section magnetizing magnet; the first pipe section steel brush is sleeved on the outer side wall of the first pipe section magnetizing magnet, and the second pipe section steel brush is sleeved on the outer side wall of the second pipe section magnetizing magnet;

[0011] The plurality of probe local excitation devices include gradient-enhanced magnetization probes and probe supports. The gradient-enhanced magnetization probes are arranged on the rigid frame in a circumferential array through the probe supports.

[0012] Furthermore, when the gradient enhanced saturation magnetization internal detection device is set in the pipeline to be detected, the first pipe section steel brush and the second pipe section steel brush are in contact with the inner wall of the pipeline to be detected, so that the annular rigid skeleton and the first pipe section magnetizing magnet, the second pipe section magnetizing magnet, the first pipe section steel brush, the second pipe section steel brush and the pipeline to be detected together form a first magnetic field loop.

[0013] Furthermore, the gradient-enhanced magnetization probe includes a first probe yoke, a second probe yoke, a probe magnetizing magnet and a magnetic sensitive element; the first probe yoke, the probe magnetizing magnet, the second probe yoke and the pipeline to be inspected form a second magnetic field loop; wherein the first magnetic field loop is in the same direction as the second magnetic field loop.

[0014] Furthermore, the gradient-enhanced magnetization probe also includes a printed circuit board; the magnetic sensitive element is arranged on the printed circuit board, the magnetic sensitive element and the printed circuit board are arranged between the first probe yoke and the second probe yoke, and the first probe yoke and the second probe yoke are arranged on the probe magnetization magnet.

[0015] Furthermore, the gradient enhanced magnetization probe also includes a wear-resistant sheet, a plurality of wear-resistant nails and a probe frame; the magnetic sensitive element, the printed circuit board, the first probe yoke, the second probe yoke and the probe magnetization magnet are encapsulated in the probe frame, and the wear-resistant sheet covers the magnetic sensitive element, the first probe yoke and the second probe yoke, and is fixed by the wear-resistant nails.

[0016] Furthermore, the probe bracket includes: two probe arms and a tension spring; one end of the two probe arms is rotatably connected to the probe frame, and the other end is rotatably connected to the annular rigid frame; one end of the tension spring is fixed to the upper part of one of the probe arms, and the other end is fixed to the lower part of the other probe arm.

[0017] Furthermore, the probe bracket also includes: a plurality of screws, a strip-shaped hollow structure is provided on the probe support arm, one end of the tension spring is fixed to the upper part of the strip-shaped hollow structure of one of the probe support arms through the screws, and the other end is fixed to the lower part of the strip-shaped hollow structure of the other probe support arm.

[0018] Furthermore, the probe bracket also includes a plurality of bolts and a probe base; the probe base is fixed on the annular rigid frame, and the probe support arm is rotatably connected to the base through the bolts.

[0019] Furthermore, the longitudinal direction of the probe magnetizing magnet is consistent with the axial direction of the pipeline to be inspected.

[0020] In a second aspect, the present invention further provides a method for gradient enhanced saturation magnetization internal detection of oil and gas pipelines, comprising:

[0021] Performing non-saturation magnetization of a first magnetization intensity on the pipeline to be inspected;

[0022] Magnetizing the local pipe section of the pipeline to be inspected covered by the gradient-enhanced magnetization probe with a second magnetization intensity;

[0023] Detecting the magnetic induction intensity of the surface of the local pipe section of the pipeline to be detected after the non-saturation magnetization and the magnetization are superimposed;

[0024] Determine whether the magnetic induction intensity of the surface reaches a preset magnetic induction intensity threshold; if the magnetic induction intensity of the surface reaches the magnetic induction intensity threshold, the local pipe section of the pipeline to be detected reaches saturation magnetization;

[0025] The leakage magnetic field information of the leakage magnetic field in the space is collected in real time, and if the leakage magnetic field information exists in the space, a voltage signal corresponding to the leakage magnetic field information is output.

[0026] The embodiment of the present invention provides a device and method for gradient-enhanced saturation magnetization internal detection of oil and gas pipelines. The local area of ​​the pipeline covered by the leakage magnetic detection probe is saturated magnetized by the gradient-enhanced excitation method. The gradient-enhanced saturation magnetization internal detection device includes a pipe segment excitation device and a probe local excitation device. The pipe segment excitation device applies non-saturation magnetization to the pipe segment to be detected, and then the probe local excitation device applies saturation magnetization to the local pipe segment to be detected. Under the superposition of the pipe segment excitation device and the probe local excitation device, the local pipeline area covered by the probe reaches saturation magnetization, thereby realizing gradient-enhanced saturation magnetization of the local area of ​​the pipeline. When there are defects in the pipe segment in the area covered by the probe, part of the magnetic lines of force leak out of the material surface to form a leakage magnetic field. The magnetic field is detected by the magnetic sensitive element inside the probe, thereby realizing the leakage magnetic detection of defects in lightweight pipelines. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work. In the drawings:

[0028] Figure 1 This is a schematic diagram of a gradient-enhanced saturation magnetization internal detection device for oil and gas pipelines in one embodiment of the present invention;

[0029] Figure 2 A three-dimensional structural diagram of a gradient-enhanced saturation magnetization internal detection device for oil and gas pipelines in one embodiment of the present invention;

[0030] Figure 3 A side-view three-dimensional structural diagram of a gradient-enhanced magnetization probe in one embodiment of the present invention;

[0031] Figure 4 A top-down three-dimensional structural diagram of a gradient-enhanced magnetization probe in one embodiment of the present invention;

[0032] Figure 5 A three-dimensional structural diagram of a local excitation device of a probe in one embodiment of the present invention;

[0033] Figure 6 This is a flow chart of a method for gradient-enhanced saturation magnetization internal detection of oil and gas pipelines in one embodiment of the present invention;

[0034] Figure 7 The figure is a curve diagram of the change of the magnetization intensity of a local area of ​​the pipeline to be detected in one embodiment of the present invention. DETAILED DESCRIPTION

[0035] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0036] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so as to describe the embodiments of the present invention described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0037] In the present invention, the directions or positional relationships indicated by the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inner", "outer", "middle", "vertical", "horizontal", "lateral", "longitudinal" and the like are based on the directions or positional relationships shown in the drawings. These terms are mainly used to better describe the present invention and its embodiments, and are not used to limit the indicated devices, elements or components to have a specific direction, or to be constructed and operated in a specific direction.

[0038] In addition, some of the above terms may be used to express other meanings in addition to indicating orientation or positional relationship. For example, the term "on" may also be used to express a certain dependency or connection relationship in some cases. For those skilled in the art, the specific meanings of these terms in the present invention can be understood according to specific circumstances.

[0039] In addition, the terms "installed", "set", "provided with", "connected", "connected", and "socketed" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be an internal connection between two devices, elements, or components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0040] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0041] In order to perform magnetic flux leakage detection on the internal and external defects of medium and low pressure oil and gas pipelines, the present invention provides a gradient enhanced saturation magnetization internal detection device for oil and gas pipelines. By applying an external magnetic field to the pipeline to be detected, the pipeline to be detected is magnetized to a non-saturated magnetization state, and then an external magnetic field is applied to a local pipe section of the pipeline to be detected, so that the local pipe section of the pipeline to be detected is magnetized to a saturated state. When there are internal and external defects in the pipeline to be detected, part of the magnetic lines of force will leak out of the pipeline surface to form a leakage magnetic field. The magnetic flux leakage signal of the leakage magnetic field is detected by the magnetic sensitive element of the gradient enhanced saturation magnetization internal detection device, and the existence and characteristics of the defect can be determined.

[0042] like Figure 1 and Figure 2 As shown, the gradient enhanced saturation magnetization internal detection device 10 includes: a pipe segment excitation device 11 and a probe local excitation device 12.

[0043] like Figure 2 As shown, the pipe segment excitation device 11 includes: an annular rigid frame 101, a pipe segment magnetizing magnet 102, a pipe segment magnetizing magnet 103, a pipe segment steel brush 104 and a pipe segment steel brush 105. The pipe segment magnetizing magnet 102 and the pipe segment magnetizing magnet 103 are a group of annular magnets, respectively. The pipe segment steel brush 104 and the pipe segment steel brush 105 are a group of annular yokes, respectively.

[0044] The pipe segment magnetizing magnet 102 and the pipe segment magnetizing magnet 103 are respectively sleeved on the outer side wall of the annular rigid frame 101, and the polarities of the pipe segment magnetizing magnet 102 and the pipe segment magnetizing magnet 103 are opposite. The pipe segment steel brush 104 is sleeved on the outer side wall of the pipe segment magnetizing magnet 102, and the pipe segment steel brush 105 is sleeved on the outer side wall of the pipe segment magnetizing magnet 103.

[0045] like Figure 1 and Figure 2 As shown, when the gradient enhanced saturation magnetization internal detection device 10 is set in the pipeline to be detected 111, the pipe section steel brush 104 and the pipe section steel brush 105 are in contact with the inner wall of the pipeline to be detected 111, so that the annular rigid skeleton 101 and the pipe section magnetizing magnet 102, the pipe section magnetizing magnet 103, the pipe section steel brush 104, the pipe section steel brush 105 and the pipeline to be detected 111 together form a magnetic field loop to apply non-saturation magnetization to the pipeline to be detected 111.

[0046] like Figure 1 and Figure 2 As shown, a plurality of probe local excitation devices 12 are arranged in a circumferential array on an annular rigid frame 101. Figure 1 , Figure 3 and Figure 4 As shown, the probe local excitation device 12 includes: a gradient-enhanced magnetization probe 106 and a probe bracket 112. One end of each probe bracket 112 is fixed to the annular rigid frame 101, and the other end is connected to the gradient-enhanced magnetization probe 106, so that the probe local excitation device 12 is arranged circumferentially on the annular rigid frame 101.

[0047] In one embodiment, the annular rigid frame 101 is a carbon steel mechanical frame of the gradient enhanced saturation magnetization internal detection device 10. The annular magnet is made of ferrite with high magnetic permeability, and the annular yoke is made of neodymium iron boron with high coercivity.

[0048] In one embodiment, a plurality of probe local excitation devices 12 are disposed in the middle of the annular rigid frame 101 , and are capable of array-detecting the leakage magnetic field information of the leakage magnetic field of the pipeline 111 to be inspected.

[0049] like Figure 1 and Figure 2 As shown, the gradient enhanced magnetization probe 106 includes: a probe magnetization magnet 107 , a probe yoke 108 , a probe yoke 109 and a magnetic sensitive element 110 .

[0050] When the gradient-enhanced saturation magnetization internal detection device 10 is set in the pipeline to be detected 111, all the gradient-enhanced magnetization probes 106 are in contact with the inner wall of the pipe section of the pipeline to be detected 111 along the circumferential direction of the pipeline to be detected 111, and the probe yoke 108, the probe yoke 109, the probe magnetization magnet 107 and the local pipe section of the pipeline to be detected 111 together form a magnetic field loop, so that the local pipe section of the pipeline to be detected 111 covered by the gradient-enhanced magnetization probe 106 reaches saturation magnetization.

[0051] In one embodiment, the longitudinal direction of the probe magnetizing magnet 107 is consistent with the axial direction of the pipeline 111 to be detected. Figure 3 As shown, the arrow direction is parallel to the axial direction of the pipeline to be detected 111. The magnetic field loop formed by the pipe segment excitation device 11 and the pipeline to be detected 111 is in the same direction as the magnetic field loop formed by the gradient enhanced magnetization probe 106 and the local pipe segment of the pipeline to be detected 111.

[0052] In one embodiment, the probe yoke 108 and the probe yoke 109 are made of high coercivity NiFeB. The probe magnetizing magnet 107 is made of high permeability ferrite. The magnetic sensor 110 can be a Hall element, a TMR element or an AMR element, etc. The magnetic sensor 110 is used to collect leakage magnetic information of the leakage magnetic field in space.

[0053] like Figure 3 and Figure 4As shown, the gradient enhanced magnetization probe 106 further includes a printed circuit board (PCB) 301 , a probe frame 302 , a wear-resistant sheet 401 and a plurality of wear-resistant pins 402 .

[0054] Specifically, the printed circuit board 301 is disposed between the probe yoke 108 and the probe yoke 109 , the magnetic sensitive element 110 is disposed on the printed circuit board 301 , and the probe yoke 108 and the probe yoke 109 are disposed on the probe magnetizing magnet 107 .

[0055] like Figure 3 And such as Figure 4 As shown, the probe yoke 108 , the probe yoke 109 , the magnetic sensitive element 110 , the printed circuit board 301 and the probe magnetizing magnet 107 are encapsulated in the probe frame 302 through a wear-resistant sheet 401 and two wear-resistant nails 402 , and the wear-resistant sheet 401 covers the probe yoke 108 , the probe yoke 109 and the magnetic sensitive element 110 .

[0056] In one embodiment, the wear-resistant sheet 401 is made of ceramics and is used to protect the core components of the gradient enhanced magnetization probe 106. The probe frame 302 is used to support the probe magnetization magnet 107, the probe yoke 108, the probe yoke 109 and the magnetic sensitive element 110.

[0057] like Figure 5 As shown, the probe bracket 112 includes: a probe support arm 501 , a tension spring 502 , a probe support arm 503 , a probe base 504 , a screw 505 , a screw 506 , a bolt 507 , a bolt 508 , a bolt 509 and a bolt 510 .

[0058] In one embodiment, the upper ends of the probe arms 501 and 503 are rotatably connected to the probe frame 302. The probe arms 501 and 503 are rotatably connected to the annular rigid frame 101. One end of the tension spring 502 is fixed to the upper part of the probe arm 503, and the other end of the tension spring 502 is fixed to the lower part of the probe arm 501 to stabilize the connection.

[0059] In specific implementation, two through holes are respectively provided at the upper and lower ends of the probe arms 501 and 503. The lower ends of the probe arms 501 and 503 are rotatably connected to the probe base 504 through bolts 507 and 508. The upper ends of the probe arms 501 and 503 are rotatably connected to the probe frame 302 through bolts 509 and 510.

[0060] In one embodiment, a strip-shaped hollow structure is provided in the middle section of the probe support arm 501 and the probe support arm 503, and two through holes are respectively provided in the upper and lower parts of the hollow structure. The screw 505 is provided in the two through holes in the lower part of the probe support arm 501, and the screw 506 is provided in the two through holes in the upper part of the probe support arm 503. Hooks are provided at both ends of the tension spring 502. The hook at one end of the tension spring 502 is hung on the screw 505, and the hook at the other end of the tension spring 502 is hung on the screw 506, so that the tension spring 502 is arranged between the probe support arm 501 and the probe support arm 503.

[0061] In one embodiment, the probe bracket 112 is a parallelogram bracket, which is used to support the gradient-enhanced magnetization probe 106. The parallelogram bracket keeps the detection plane of the gradient-enhanced magnetization probe 106 horizontal with the inner wall of the pipeline to be detected, so as to ensure that the magnetic sensitive element 110 can collect the axial, radial and circumferential leakage magnetic field information of the pipeline to be detected in real time. The tension spring 502 is used to provide tension to the probe bracket 112 so that the gradient-enhanced magnetization probe 106 is in close contact with the inner wall of the pipeline to be detected.

[0062] like Figure 6 As shown, the present invention also provides a method for gradient enhanced saturation magnetization internal detection of oil and gas pipelines. Before detecting the pipeline 111 to be detected, the gradient enhanced saturation magnetization internal detection device 10 is placed in the pipeline 111 to be detected. The gradient enhanced saturation magnetization internal detection method includes steps 1 to 5.

[0063] Step 1: Perform non-saturation magnetization of a first magnetization intensity on the pipeline to be inspected.

[0064] Step 2: Magnetizing the local pipe section of the pipeline to be inspected covered by the gradient-enhanced magnetization probe with a second magnetization intensity.

[0065] Step 3: Detect the magnetic induction intensity on the surface of the local pipe section of the pipeline to be detected after the unsaturated magnetization of the first magnetization intensity and the magnetization of the second magnetization intensity are superimposed.

[0066] Step 4: Determine whether the magnetic induction intensity on the surface of the local pipe section of the pipeline to be detected reaches a preset magnetic induction intensity threshold; if the magnetic induction intensity on the surface of the local pipe section of the pipeline to be detected reaches the magnetic induction intensity threshold, the local pipe section of the pipeline to be detected reaches saturation magnetization.

[0067] Step 5: Collect the leakage magnetic field information of the leakage magnetic field in the space in real time. If there is leakage magnetic field information in the space, output the voltage signal corresponding to the leakage magnetic field information.

[0068] As can be seen from the process shown in FIG6 , in the embodiment of the present invention, the non-saturated magnetization of the first magnetization intensity is applied to the pipeline to be inspected, and then the local pipe section of the pipeline to be inspected is magnetized to the second magnetization level. Under the superposition of the pipe section excitation device and the probe local excitation device, the local pipe section of the pipeline to be inspected covered by the probe reaches saturation magnetization, and gradient-enhanced local area saturation magnetization of the pipeline is realized. When there are defects in the pipeline in the probe coverage area, part of the magnetic lines of force will leak into the space and be captured by the magnetic sensitive element, thereby realizing lightweight leakage magnetic internal detection of pipeline defects.

[0069] Each step is explained in detail below.

[0070] Step 1: Perform non-saturation magnetization of a first magnetization intensity on the pipeline 111 to be inspected.

[0071] The first magnetization intensity is a non-saturation magnetization intensity M1.

[0072] Specifically, a magnetic field loop is formed by the annular rigid frame 101, the pipe segment magnetizing magnet 102, the pipe segment magnetizing magnet 103, the pipe segment steel brush 104, the pipe segment steel brush 105 and the pipeline to be detected 111. The direction of the magnetic field is as follows: Figure 1 As shown. The pipe section excitation device 11 performs non-saturation magnetization with a non-saturation magnetization intensity of M1 on the pipeline 111 to be detected. At this time, the magnetic field intensity inside the pipeline 111 to be detected is H1, which is much smaller than the preset magnetic field intensity threshold H max , that is, H max is the saturation magnetic field strength.

[0073] In one embodiment, the magnetic field strength inside the pipeline 111 to be inspected is determined by a magnetic susceptibility formula.

[0074] X=M / H (1)

[0075] in, is the magnetic susceptibility, the unit is H / m; M is the magnetization intensity, the unit is A / m; H is the magnetic field intensity, the unit is A / m.

[0076] Step 2: magnetize the local pipe section of the pipeline to be inspected 111 covered by the gradient-enhanced magnetization probe 106 with a second magnetization intensity, wherein the second magnetization intensity is the magnetization intensity M2.

[0077] Specifically, the gradient-enhanced magnetization probe 106 contacts the inner wall of the pipeline 111 to be inspected under the action of the magnetic attraction force of the probe support 112 and the probe interior. A magnetic field loop is formed by the probe yoke 108, the probe yoke 109, the probe magnetization magnet 107 and the local pipe section of the pipeline 111 to be inspected inside the gradient-enhanced magnetization probe 106. The direction of the magnetic field is as follows: Figure 1The gradient enhanced magnetization probe 106 is used to magnetize a local pipe section of the pipeline 111 to be inspected with a magnetization intensity M2, and the magnetic field intensity H2 at the magnetization intensity M2 is calculated by formula (1).

[0078] Step 3: Detect the magnetic induction intensity B on the surface of the local pipe section of the pipeline 111 to be detected after the unsaturated magnetization of the first magnetization intensity and the magnetization of the second magnetization intensity are superimposed. s .

[0079] Specifically, under the superposition of the pipe segment excitation device 11 and the probe local excitation device 12, the internal magnetic field strength of the local pipe segment of the pipeline to be detected 111 covered by the gradient enhanced magnetization probe 106 is H s , that is, H s =H1+H2. The magnetic induction intensity B of the outer surface of the pipeline 111 to be inspected covered by the gradient-enhanced magnetization probe 106 is measured by a Gauss meter. s .

[0080] Step 4: Determine the magnetic induction intensity B on the surface of the local pipe section of the pipeline 111 to be detected s Whether the preset magnetic induction intensity threshold B is reached max If the magnetic induction intensity B on the surface of the local pipe section of the pipeline 111 to be detected is s Reaching the magnetic induction intensity threshold B max , the local pipe section of the pipeline 111 to be detected reaches saturation magnetization.

[0081] Step 5: Collect the leakage magnetic field information of the leakage magnetic field in the space in real time. If there is leakage magnetic field information in the space, output the voltage signal corresponding to the leakage magnetic field information.

[0082] Specifically, after the local pipe section of the pipeline to be inspected 111 covered by the gradient-enhanced magnetization probe 106 reaches saturation magnetization, the magnetic field information of the leakage magnetic field in the space is detected by the magnetic sensitive element 110 inside the gradient-enhanced magnetization probe 106. When there are defects in the inner and outer walls of the pipeline to be inspected 111 that is partially saturated magnetized, part of the magnetic field lines will leak into the space and be captured by the magnetic sensitive element 110 inside the gradient-enhanced magnetization probe 106. The gradient-enhanced magnetization probe 106 will output a voltage signal corresponding to the leakage magnetic information, thereby realizing the leakage magnetic detection of the local pipe section of the pipeline to be inspected 111.

[0083] In one embodiment, the voltage signal output by the gradient-enhanced magnetization probe 106 is stored.

[0084] like Figure 7As shown, when the pipeline to be detected 111 is subjected to non-saturated magnetization with a magnetization intensity of M1, the magnetic field intensity inside the pipeline to be detected is H1. At this time, the pipeline to be detected is magnetized to point a, and the magnetic induction intensity of the pipeline wall to be detected corresponding to the magnetic field intensity H1 is B1. The pipeline to be detected 111 is in a non-saturated magnetization state.

[0085] Specifically, the magnetic field strength H1 is calculated by formula (1), that is, H1=M1 / X.

[0086] The magnetic induction intensity B1 corresponding to the magnetic field intensity H1 is calculated by formula (2):

[0087] B = μ (H + M) (2)

[0088] Where B is the magnetic induction intensity, is the magnetic permeability in vacuum, H is the magnetic field strength, and M is the magnetization intensity.

[0089] That is, B1=μ(H1+M1).

[0090] When the local pipe section of the pipeline to be inspected 111 covered by the gradient enhanced magnetization probe 106 is magnetized with a magnetization intensity M2, the local pipe section of the pipeline to be inspected is magnetized from point a to point s, and the magnetic field intensity H s The corresponding magnetic induction intensity of the local pipe wall of the pipeline to be tested is B S , the local pipe section of the pipeline 111 to be detected is in a saturated magnetization state.

[0091] Specifically, the magnetic field intensity H2 is calculated by formula (1), that is, H2=M2 / X. The magnetic induction intensity B2 corresponding to the magnetic field intensity H2 is calculated by formula (2), that is, B2=μ(H2+M2). Then the magnetic induction intensity B S = B1+B2, magnetic field strength H s It is H1+H2.

[0092] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A gradient enhanced saturation magnetization internal detection device for oil and gas pipelines, characterized in that: include: Pipe section excitation device and multiple probe local excitation devices; The pipe section excitation device comprises: an annular rigid frame, a first pipe section magnetizing magnet, a second pipe section magnetizing magnet, a first pipe section steel brush and a second pipe section steel brush; the first pipe section magnetizing magnet, the second pipe section magnetizing magnet, the first pipe section steel brush and the second pipe section steel brush are all annular structures; the first pipe section magnetizing magnet and the second pipe section magnetizing magnet are respectively sleeved on the outer side wall of the annular rigid frame, and the polarity of the first pipe section magnetizing magnet is opposite to that of the second pipe section magnetizing magnet; the first pipe section steel brush is sleeved on the outer side wall of the first pipe section magnetizing magnet, and the second pipe section steel brush is sleeved on the outer side wall of the second pipe section magnetizing magnet; The plurality of probe local excitation devices include gradient-enhanced magnetization probes and probe supports, and the gradient-enhanced magnetization probes are arranged on the rigid frame in a circumferential array through the probe supports; When the gradient enhanced saturation magnetization internal detection device is set in the pipeline to be detected, the first pipe section steel brush and the second pipe section steel brush are in contact with the inner wall of the pipeline to be detected, so that the annular rigid frame and the first pipe section magnetization magnet, the second pipe section magnetization magnet, the first pipe section steel brush, the second pipe section steel brush and the pipeline to be detected together form a first magnetic field loop; The gradient-enhanced magnetization probe comprises a first probe yoke, a second probe yoke, a probe magnetization magnet and a magnetic sensitive element; the first probe yoke, the probe magnetization magnet, the second probe yoke and the pipeline to be detected form a second magnetic field loop; wherein the first magnetic field loop and the second magnetic field loop have the same direction; The longitudinal direction of the magnetizing magnet of the probe is consistent with the axial direction of the pipeline to be detected.

2. The device according to claim 1, characterized in that The gradient-enhanced magnetization probe also includes a printed circuit board; the magnetic sensitive element is arranged on the printed circuit board, the magnetic sensitive element and the printed circuit board are arranged between the first probe yoke and the second probe yoke, and the first probe yoke and the second probe yoke are arranged on the probe magnetization magnet.

3. The device according to claim 2, characterized in that The gradient enhanced magnetization probe also includes a wear-resistant sheet, a plurality of wear-resistant nails and a probe frame; the magnetic sensitive element, the printed circuit board, the first probe yoke, the second probe yoke and the probe magnetization magnet are encapsulated in the probe frame, and the wear-resistant sheet covers the magnetic sensitive element, the first probe yoke and the second probe yoke, and is fixed by the wear-resistant nails.

4. The device according to claim 3, characterized in that The probe bracket includes: two probe arms and a tension spring; one end of the two probe arms is rotatably connected to the probe frame, and the other end is rotatably connected to the annular rigid frame; one end of the tension spring is fixed to the upper part of one of the probe arms, and the other end is fixed to the lower part of the other probe arm.

5. The device according to claim 4, characterized in that The probe bracket also includes: a plurality of screws, the probe arm is provided with a strip hollow structure, one end of the tension spring is fixed to the upper part of the strip hollow structure of one of the probe arms through the screws, and the other end is fixed to the lower part of the strip hollow structure of the other probe arm.

6. The device according to claim 5, characterized in that The probe bracket also includes a plurality of bolts and a probe base; the probe base is fixed on the annular rigid frame, and the probe support arm is rotatably connected to the base through the bolts.

7. A method for internal detection of oil and gas pipelines by gradient-enhanced saturation magnetization, applied to the internal detection device for oil and gas pipelines by gradient-enhanced saturation magnetization according to any one of claims 1 to 6, characterized in that: include: Performing non-saturation magnetization of a first magnetization intensity on the pipeline to be inspected; Magnetizing the local pipe section of the pipeline to be inspected covered by the gradient-enhanced magnetization probe with a second magnetization intensity; Detecting the magnetic induction intensity of the surface of the local pipe section of the pipeline to be detected after the non-saturation magnetization and the magnetization are superimposed; Determine whether the magnetic induction intensity of the surface reaches a preset magnetic induction intensity threshold; if the magnetic induction intensity of the surface reaches the magnetic induction intensity threshold, the local pipe section of the pipeline to be detected reaches saturation magnetization; The leakage magnetic field information of the leakage magnetic field in the space is collected in real time, and if the leakage magnetic field information exists in the space, a voltage signal corresponding to the leakage magnetic field information is output.

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