A dual-type guided wave integrated acoustic logging system for cementing quality detection

Abstract

The present invention belongs to the field of acoustic logging technology, and in particular, relates to a dual-type waveguide integrated acoustic logging system for cementing quality detection. The dual-type waveguide integrated acoustic logging system forms a static magnetic field loop in the casing to be inspected by means of an annular magnetic conductor and a plurality of electromagnet units; and further integrates the circumferential SH waveguide unit and the circumferential A0 modal waveguide unit into the same circumferential position inside the casing to be inspected. The dual-type waveguide integrated acoustic logging system includes: an annular magnetic conductor, a plurality of electromagnet units, a plurality of circumferential SH waveguide units, and a plurality of circumferential A0 modal waveguide units. Among them, the electromagnet unit is composed of a magnetic core and an excitation coil, and the excitation coil is evenly wound around the periphery of the magnetic core; the circumferential SH waveguide unit is composed of a plurality of inner cores and a plurality of eddy current winding coils, each inner core is evenly wound with a section of eddy current winding coil, and the plurality of eddy current winding coils are connected in series.

Description

Technical Field

[0001] The invention belongs to the technical field of acoustic logging, and in particular relates to a dual-type waveguide integrated acoustic logging system for cementing quality detection. Background Art

[0002] Cementing refers to the construction work of injecting cement between the formation and the casing to form a cement ring during the oil and gas production process. This process is an indispensable and important part of the drilling and completion operation, which plays the role of supporting the casing and interlayer isolation. Among them, the bonding conditions of the interface between the cement ring and the casing (referred to as the "first interface") and the interface between the cement ring and the formation (referred to as the "second interface") directly affect the safety and stability of oil and gas production. Therefore, it is of great significance to carry out the detection and evaluation of cement bonding quality (i.e. cementing quality).

[0003] Among them, acoustic logging technology is one of the most commonly used cementing quality detection methods, including acoustic amplitude-variable density logging, sector cement bonding logging and various acoustic impedance logging methods. However, due to the frequent use of low-density cement for cementing in oil fields, as well as the emergence of thick casing and heavy mud in deep wells, the applicability of traditional acoustic logging technology is greatly limited. At the same time, the detection sensitivity of existing methods is also relatively insufficient, making it difficult for technicians to make accurate evaluations.

[0004] In order to overcome the above technical problems, technicians have found that using electromagnetic acoustic transducers to excite circumferential A0 modal guided waves and circumferential SH guided waves propagating along the circumference of the casing, and combining the leakage attenuation of different types of guided waves for cementing quality detection, can better solve the problems of incompatibility of detection methods and low sensitivity of detection results encountered in existing methods. However, after further research, the inventors found that due to the limited space inside the casing, it is difficult for technicians to simultaneously arrange multiple existing circumferential A0 modal electromagnetic acoustic transducers and circumferential SH guided wave electromagnetic acoustic transducers on the same circumference of the inner wall of the casing. Different circumferential positions may lead to the problem that the results obtained from the two guided wave detections are difficult to match, thereby reducing the accuracy and detection efficiency of the cementing quality detection results. Therefore, it is urgent for technical personnel in this field to provide a new integrated electromagnetic acoustic transducer that can excite both circumferential SH guided waves and circumferential A0 modal guided waves. Summary of the invention

[0005] The present invention provides a dual-type waveguide integrated acoustic logging system for cementing quality detection. The dual-type waveguide integrated acoustic logging system forms a static magnetic field loop in the casing to be inspected by means of an annular magnetic conductor and multiple electromagnet units; and further integrates the circumferential SH waveguide unit and the circumferential A0 modal waveguide unit into the same circumferential position inside the casing to be inspected, thereby achieving the purpose of keeping the detection process of the two types of waveguides always in the same circumferential direction of the casing to be inspected.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] A dual-type guided wave integrated acoustic logging system for cementing quality detection, comprising:

[0008] Ring-shaped magnetic conductor;

[0009] A plurality of electromagnet units; the electromagnet units are arranged at equal intervals along the circumferential direction of the casing to be inspected on the annular outer side of the annular magnetic conductor; wherein the electromagnet units are composed of a magnetic core and an excitation coil, the axial direction of the magnetic core is arranged along a direction perpendicular to the tangential direction of the annular magnetic conductor, and the excitation coil is evenly wound around the periphery of the magnetic core;

[0010] A plurality of circumferential SH waveguide units; the circumferential SH waveguide units are arranged in one-to-one correspondence with the electromagnet units; the circumferential SH waveguide units are composed of a plurality of inner cores and a plurality of sections of eddy current winding coils; wherein the plurality of inner cores of the same circumferential SH waveguide unit are arranged side by side at equal intervals and between the magnetic core and the inner wall of the casing to be inspected, and the length direction of the inner core is parallel to the axial direction of the casing to be inspected; a section of eddy current winding coil is evenly wound on each inner core, and the plurality of sections of eddy current winding coils are connected in series;

[0011] A plurality of circumferential A0 modal waveguide units; the circumferential A0 modal waveguide units are arranged on the inner wall of the casing to be inspected at the middle position of adjacent electromagnet units; wherein the length direction of the circumferential A0 modal waveguide units is parallel to the axial direction of the casing to be inspected, and the circumferential A0 modal waveguide units and the annular magnetic conductor are located in the same circumferential direction of the casing to be inspected.

[0012] Preferably, the annular magnetic conductor is coaxially arranged with the casing to be inspected, and its material is selected to be a magnetic and non-conductive ferrite.

[0013] Preferably, the number of electromagnet units provided is six groups;

[0014] Adjacent electromagnet units are arranged at an angle of 60°, and the directions of the static bias magnetic fields provided by adjacent electromagnet units and distributed along the radial direction of the casing to be inspected are opposite.

[0015] More preferably, in the same circumferential SH waveguide unit, the current directions of the eddy current winding coils wound on adjacent inner cores arranged side by side at equal intervals are arranged in opposite directions.

[0016] More preferably, the width of any inner core in the circumferential SH waveguide unit plus the interval between adjacent inner cores arranged side by side at equal intervals is equal to half the wavelength of the circumferential SH waveguide excited by the circumferential SH waveguide unit.

[0017] Preferably, the circumferential A0 modal waveguide unit is made of flexible PCB material; wherein the center distance between two straight line segments in the circumferential A0 modal waveguide unit is equal to half the wavelength of the circumferential A0 modal waveguide wavelength excited by the circumferential A0 modal waveguide unit.

[0018] The present invention provides a dual-type waveguide integrated acoustic logging system for cementing quality detection, comprising: an annular magnetic conductor, an electromagnet unit, a circumferential SH waveguide unit, and a circumferential A0 modal waveguide unit. The electromagnet unit is composed of a magnetic core and an excitation coil, and the excitation coil is evenly wound around the periphery of the magnetic core; the circumferential SH waveguide unit is composed of a plurality of inner cores and a plurality of eddy current winding coils, each inner core is evenly wound with a section of eddy current winding coil, and the plurality of eddy current winding coils are connected in series.

[0019] The dual-type waveguide integrated acoustic logging system for cementing quality detection having the above structural features has at least the following beneficial effects compared with the prior art:

[0020] 1) In the integrated acoustic logging system provided by the present invention, the circumferential SH waveguide unit and the circumferential A0 mode waveguide unit are always kept at the same circumferential position inside the casing to be inspected during the inspection process, so that the two types of waveguides have the same circumferential initial conditions, thereby providing help to ensure the accuracy of cementing quality inspection results;

[0021] 2) The integrated acoustic logging system provided by the present invention has an integrated circumferential SH waveguide unit and a circumferential A0 modal waveguide unit, so that the structure of the integrated acoustic logging system can respectively realize the excitation and reception of the circumferential SH waveguide and the circumferential A0 modal waveguide, which helps to simplify the cementing quality detection process and improve the cementing quality detection efficiency;

[0022] 3) The integrated acoustic logging system provided by the present invention uses an electromagnet unit to generate a static bias magnetic field, which fundamentally solves a series of problems in the prior art, such as difficulty in movement and probe wear caused by adsorption of iron filings during the mobile detection process of the permanent magnetic field structure in the casing. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the following drawings:

[0024] Figure 1 A schematic diagram of the structure of the dual-type waveguide integrated acoustic logging system provided by the present invention;

[0025] Figure 1a It is a schematic diagram of the structure of the electromagnetic unit in the dual-type guided wave integrated acoustic logging system;

[0026] Figure 1b It is a schematic diagram of the structure of the circumferential SH waveguide unit in the dual-type waveguide integrated acoustic logging system;

[0027] Figure 1c It is a schematic diagram of the structure of the circumferential A0 mode waveguide unit in the dual-type waveguide integrated acoustic logging system;

[0028] Figure 2 It is a schematic diagram of the static magnetic field distribution formed when the electromagnet unit is working;

[0029] Figure 3 Schematic diagram of the circumferential SH guided wave excitation principle;

[0030] Figure 4 Schematic diagram of the circumferential A0 mode guided wave excitation principle;

[0031] Figure 5 It is a schematic diagram of the collaborative working principle of the dual-type guided wave integrated acoustic logging system;

[0032] Figure 6 This is the phase velocity dispersion curve of SH guided waves in the inner circumferential direction of the casing to be inspected with a thickness of 9.5 mm and an inner diameter of 204 mm;

[0033] Figure 7 This is the SH guided wave group velocity dispersion curve of the inner circumferential direction of the casing to be inspected with a thickness of 9.5mm and an inner diameter of 204mm;

[0034] Figure 8 This is the dispersion curve of the circumferential Lamb wave phase velocity in the casing to be inspected with a thickness of 9.5 mm and an inner diameter of 204 mm;

[0035] Fig. 9 This is the dispersion curve of Lamb wave group velocity in the inner circumferential direction of the casing to be inspected with a thickness of 9.5mm and an inner diameter of 204mm;

[0036] Fig.10 It is a simulation model for exciting circumferential SH0 mode guided waves in the casing to be inspected;

[0037] Fig.10a for Fig.10 The locally enlarged schematic diagram of the simulation model of the circumferential SH0 mode guided wave excited in the casing to be inspected is shown;

[0038] Fig.11It is the magnetic flux density distribution result of the static magnetic field generated by a single electromagnet unit;

[0039] Fig.12 This is a snapshot of the x-direction displacement field of the axial section at 42.5 μs;

[0040] Fig.13 is the time domain waveform of the displacement in the x direction of point P;

[0041] Fig.14 It is a simulation model for exciting circumferential A0 mode guided waves in the casing to be inspected;

[0042] Fig.15 It is the magnetic flux density distribution result of the static magnetic field generated by two groups of adjacent electromagnet units;

[0043] Fig.16 This is a snapshot of the displacement field in the y direction of the axial section at the time of 72μs;

[0044] Fig.17 is the time domain waveform of the displacement in the y direction of point Q;

[0045] Figure numerals: 1. annular magnetic conductor; 100. casing to be inspected; 101. cement ring; 102. air domain; 103. refined air domain; 104. skin layer refinement area; 2. electromagnet unit; 3. circumferential SH waveguide unit; 4. circumferential A0 modal waveguide unit; 5. excitation coil; 6. magnetic core; 7. eddy current winding coil; 8. inner core. DETAILED DESCRIPTION

[0046] The present invention provides a dual-type waveguide integrated acoustic logging system for cementing quality detection. The dual-type waveguide integrated acoustic logging system forms a static magnetic field loop in the casing to be inspected by means of an annular magnetic conductor and multiple electromagnet units; and further integrates the circumferential SH waveguide unit and the circumferential A0 modal waveguide unit into the same circumferential position inside the casing to be inspected, thereby achieving the purpose of keeping the detection process of the two types of waveguides always in the same circumferential direction of the casing to be inspected.

[0047] The present invention provides a dual-type waveguide integrated acoustic logging system for cementing quality detection, such as Figure 1 As shown, it specifically includes an annular magnetic conductor 1, multiple electromagnet units 2, multiple circumferential SH waveguide units 3, and multiple circumferential A0 modal waveguide units 4.

[0048] A plurality of electromagnet units 2 are arranged on the outer side of the annular magnetic conductor 1 at equal intervals along the circumference of the casing 100 to be inspected. Figure 1aAs shown, the electromagnet unit 2 is specifically composed of a magnetic core 6 and an excitation coil 5. The axial direction of the magnetic core 6 is arranged perpendicular to the tangential direction of the annular magnetizer 1, and the excitation coil 5 is evenly wound around the periphery of the magnetic core 6. The electromagnet unit 2 is used to cooperate with the annular magnetizer 1 to form a static bias magnetic field distributed along the radial and circumferential directions of the casing 100 to be inspected.

[0049] The plurality of circumferential SH waveguide units 3 are arranged in one-to-one correspondence with the plurality of electromagnet units 2. Figure 1b As shown, the circumferential SH waveguide unit 3 is specifically composed of multiple inner cores 8 and multiple sections of eddy current winding coils 7. Among them, multiple inner cores 8 of the same circumferential SH waveguide unit 3 are arranged side by side at equal intervals and arranged between the magnetic core 6 and the inner wall of the casing 100 to be inspected, and the length direction of the inner core 8 (the direction shown by the reference numeral 1) is parallel to the axial direction of the casing 100 to be inspected. A section of eddy current winding coil 7 is evenly wound on each inner core 8, and multiple sections of eddy current winding coils 7 are connected in series. Specifically, refer to Figure 1b As shown, the same group of circumferential SH waveguide units 3 is provided with inner cores 8 arranged side by side and eddy current winding coils 7 connected in series. The current directions of the eddy current winding coils 7 arranged in series are arranged in opposite directions.

[0050] The circumferential A0 modal waveguide unit 4 is arranged on the inner wall of the casing 100 to be inspected at the middle position of the adjacent electromagnet units 2. Figure 1c As shown, the length direction (the direction indicated by reference numeral g) of the circumferential A0 modal waveguide unit 4 is parallel to the axial direction of the casing 100 to be inspected, and the circumferential A0 modal waveguide unit 4 and the annular magnetic conductor 1 are located in the same circumferential direction of the casing 100 to be inspected.

[0051] As a more preferred embodiment of the present invention, Figure 1 As shown, the annular magnetizer 1 is coaxially arranged with the casing 100 to be inspected, and its material is selected to be a magnetic and non-conductive ferrite. The number of electromagnet units 2 is six groups; adjacent electromagnet units 2 are arranged at an angle of 60°, and the directions of the static bias magnetic fields provided by adjacent electromagnet units 2 along the radial distribution of the casing 100 to be inspected are opposite. Since a plurality of circumferential SH waveguide units 3 are arranged in a one-to-one correspondence with a plurality of electromagnet units 2, the number of circumferential SH waveguide units 3 is also six groups. It should be added that it is preferred that the magnetic core 6 of the electromagnet unit 2 is designed to be co-shaped with the outer side of the annular magnetizer 1 and the inner core 8 of the circumferential SH waveguide unit 3, respectively, so as to ensure a good fit between the three.

[0052] In addition, as a preferred embodiment of the present invention, the width (reference numeral w) of any inner core 8 in the circumferential SH waveguide unit 3 plus the interval (reference numeral n) between adjacent inner cores 8 arranged side by side at equal intervals is equal to half the wavelength of the circumferential SH waveguide excited by the circumferential SH waveguide unit 3. The circumferential A0 modal waveguide unit 4 is made of flexible PCB material, wherein the center distance (reference numeral e) between two straight line segments in the circumferential A0 modal waveguide unit 4 is equal to half the wavelength of the circumferential A0 modal waveguide excited by the circumferential A0 modal waveguide unit 4.

[0053] The working process of the dual-type guided wave integrated acoustic logging system for cementing quality detection is further described as follows:

[0054] First, direct current is passed into the excitation coil 5 of the electromagnet unit 2, and the excitation coil 5 generates a steady static bias magnetic field. The static magnetic field distribution diagram formed when the six groups of electromagnet units 2 work simultaneously can be referred to as follows: Figure 2 As shown. Arrows are used to indicate the direction of the static magnetic field in the annular magnetizer 1, the electromagnet unit 2 and the casing 100 to be inspected. It can be found that a single electromagnet unit 2 mainly provides a static bias magnetic field distributed radially along the casing 100 to be inspected (the inner core 8 of the circumferential SH waveguide unit 3 can help ensure that the static bias magnetic field smoothly enters the casing 100 to be inspected); and with the good magnetic conductivity of the annular magnetizer 1, coupled with the magnetic field direction setting of adjacent electromagnet units 2, a static magnetic field distributed along the circumference of the pipeline can be formed between every two groups of electromagnet units 2.

[0055] Then, the excitation process of the circumferential SH waveguide unit 3 can be referred to as follows Figure 3 As shown. When the technicians pass an alternating current signal (i.e., the excitation signal of the SH waveguide) through the different eddy current winding coils 7 of the circumferential SH waveguide unit 3, parallel and opposite eddy currents will be induced on the inner wall surface of the casing 100 to be inspected. Under the action of the static bias magnetic field distributed along the radial direction of the pipeline, a shear force (i.e., the Lorentz force) distributed along the axial direction of the pipeline can be generated, thereby exciting a circumferential SH waveguide that is perpendicular to the direction of the Lorentz force and propagates circumferentially along the pipeline. According to actual detection requirements, different spatial wavelengths (i.e., the size of the inner core 8), spatial period numbers (i.e., the number of inner cores 8) and excitation signals of the circumferential SH waveguide unit 3 can be selected to realize the excitation process of different modal circumferential SH waveguides.

[0056] Then, the excitation process of the circumferential A0 mode waveguide unit 4 can be referred to as follows: Figure 4As shown. When the technicians pass another alternating current signal (i.e., the excitation signal of the A0 modal waveguide) into the circumferential A0 modal waveguide unit 4, an eddy current is induced on the inner wall surface of the casing 100 to be inspected along the axial direction of the pipeline and in the opposite direction to the current signal in the circumferential A0 modal waveguide unit 4. Under the action of the static bias magnetic field distributed along the circumferential direction of the pipeline provided by the electromagnet units 2 on both sides, the Lorentz force distributed alternately along the radial direction of the pipeline can be generated, thereby exciting the circumferential A0 modal waveguide that is perpendicular to the direction of the Lorentz force and propagates along the circumferential direction of the pipeline.

[0057] At this point, it can be known from the above description of the working process that in the cementing quality detection process, the dual-type waveguide integrated acoustic logging system for cementing quality detection provided by the present invention provides the required static bias magnetic field for the excitation and reception of the circumferential SH waveguide and the circumferential A0 modal waveguide through the electromagnet unit 2, and further integrates the design to complete the circumferential SH waveguide unit 3 and the circumferential A0 modal waveguide unit 4.

[0058] In addition, in the actual detection process, the technicians can further choose to use the four integrated acoustic logging systems provided by the present invention as a unit to construct an attenuation compensation configuration (whose main purpose is to compensate for the detection result errors caused by the performance differences between different excitation units and receiving units). The working process can be referred to as follows Figure 5 As shown, 1#-6# represent circumferential SH waveguide units 3 and electromagnet units 2 at different positions, and AF represent circumferential A0 modal waveguide units 4 at different positions.

[0059] For the excitation of circumferential SH waveguide, firstly, the circumferential SH waveguide unit 3 at the 1#-4# position and the electromagnet unit 2 form an attenuation compensation unit, wherein the circumferential SH waveguide unit 3 at the 1# and 4# positions is selected as the excitation probe of the circumferential SH waveguide, and the circumferential SH waveguide unit 3 at the 2# and 3# positions is selected as the receiving probe of the circumferential SH waveguide. At this time, the measured attenuation value reflects the attenuation of the circumferential SH waveguide between 2# and 3#, and the bonding condition of the interface between the outer wall of the casing 100 to be inspected and the cement ring 101 in the area can be detected. By analogy, the circumferential SH waveguide unit 3 at the 1#-6# position and the electromagnet unit 2 are alternately excited and received to form different attenuation compensations, thereby realizing full circumferential SH waveguide detection.

[0060] The detection process of circumferential A0 modal waveguide is similar to the excitation process of the above-mentioned circumferential SH waveguide. First, the circumferential A0 modal waveguide unit 4 at the AD position is used to form an attenuation compensation unit, and the electromagnet units 2 at the 1#-5# positions respectively provide a circumferential static bias magnetic field for the circumferential A0 modal waveguide unit 4 at the AD position. Among them, the circumferential A0 modal waveguide unit 4 at the A and D positions is used as the excitation coil of the circumferential A0 modal waveguide, and the circumferential A0 modal waveguide unit 4 at the B and C positions is used as the receiving coil of the circumferential A0 modal waveguide. At this time, the attenuation value measured reflects the attenuation of the circumferential A0 modal waveguide between B and C, which can detect the bonding condition of the interface between the outer wall of the casing 100 to be inspected and the cement ring 101 in the area. By analogy, the circumferential A0 modal waveguide unit 4 at the AF position is alternately excited and received, and the electromagnet units 2 on both sides of the circumferential A0 modal waveguide unit 4 at the corresponding position cooperate to provide a circumferential static magnetic field, thereby forming different attenuation compensation units, thereby realizing full-circumferential A0 modal waveguide detection.

[0061] A set of specific embodiments of exciting and receiving circumferential SHO mode and circumferential A0 mode guided waves are further provided below to further explain a dual-type guided wave integrated acoustic logging system for cementing quality detection provided by the present invention:

[0062] The thickness of the casing 100 to be inspected is 9.5 mm, the inner diameter is 204 mm, and the transverse and longitudinal wave velocities are 3250 m / s and 5833 m / s respectively. The phase velocity and group velocity dispersion curves of the circumferential SH guided wave and the circumferential Lamb wave (including the circumferential A0 mode) in the casing 100 to be inspected are obtained as follows: Figure 6-Figure 9 As shown in (where CSH0 and CLT0 represent the circumferential SH0 mode and the circumferential A0 mode, respectively). When exciting the circumferential SH0 mode and the circumferential A0 mode waveguide, it is first necessary to combine their respective phase velocity dispersion curves to select the parameters of the circumferential SH waveguide unit 3 and the circumferential A0 mode waveguide unit 4, mainly including the wavelength and spatial period number of the excited circumferential SH0 mode and circumferential A0 mode waveguide, the center frequency of the excitation signal, the time domain period number and the adopted window function, etc.

[0063] In order to avoid exciting high-order modes and other modal waveguides and ensure that the dispersion effect of the excited circumferential A0 modal waveguide is weak, the wavelengths λ of the circumferential SH0 mode and circumferential A0 mode waveguides are determined to be 30 mm and 18.4 mm, respectively. The wavelength lines are further superimposed and plotted with their respective phase velocity dispersion curves, as shown in Figure 6 and Figure 8As shown by the inclined dotted line in the figure. According to the intersection of the two wavelength lines with the CSH0 and CLT0 modal dispersion curves, the center frequencies of the circumferential SH0 mode and circumferential A0 mode waveguide excitation signals are selected as 103kHz and 129kHz respectively. In addition, considering the size of the circumferential SH waveguide unit 3 and the circumferential A0 mode waveguide unit 4 and the frequency bandwidth of the excited waveguide, it is finally determined that the spatial period number of the circumferential SH waveguide unit 3 is 1 period (that is, two inner cores 8 and two eddy current winding coils 7 are set in the same circumferential SH waveguide unit), the wavelength λ is 30mm, and the excitation signal is a 5-period Hanning window modulated sine signal with a center frequency of 103kHz; at the same time, it is also determined that the spatial period number of the circumferential A0 mode waveguide unit 4 is 3 periods, the wavelength λ is 18.4mm, and the excitation signal is a 5-period Hanning window modulated sine signal with a center frequency of 129kHz.

[0064] After determining the excitation parameters of the circumferential SH0 mode and circumferential A0 mode guided waves, the effects of the dual-type guided wave integrated acoustic logging system on the excitation of the circumferential SH0 mode and circumferential A0 mode guided waves in the casing to be inspected were further simulated and verified. Firstly, the commercial finite element simulation software COMSOL was used to establish a simulation model for the excitation of the circumferential SH0 mode guided waves in the casing to be inspected. Fig.10 and Fig.10a As shown. It includes a group of electromagnet units 2 and circumferential SH waveguide units 3, and the size parameters of each structure can be referred to as follows: the size of the casing 100 to be inspected is 9.5mm×204mm×100mm (thickness×inner diameter×length); the size of the annular magnetizer 1 is 5mm×154mm×30mm (thickness×outer diameter×length); the wire diameter of the excitation coil 5 of the electromagnet unit 2 is 1mm, the number of turns is 50 turns, and the winding length is 18mm; the magnetic core 6 of the electromagnet unit 2 is designed in the same shape as the annular magnetizer 1, and its length and width are 30mm×30mm respectively; the circumferential SH waveguide unit 3 is composed of two eddy current winding coil 7 units, wherein the length l, width w and height c of the inner core 8 (such as Figure 1b ) are 30 mm, 12 mm and 3 mm respectively, and the interval n between the two inner cores 8 (as shown Figure 1 As shown in the figure, the width w of the inner core 8 and the spacing n are 3 mm, thereby ensuring that the sum of the width w of the inner core 8 and the spacing n is half of the wavelength of the excited circumferential SH0 mode guided wave (i.e., 15 mm); the wire diameter of the eddy current winding coil 7 is 0.15 mm, the number of turns is 140 turns, the winding length is 28 mm, and the current directions in the two eddy current winding coils 7 are kept opposite; the rectangular air domain 102 is located at the same center as the casing 100 to be inspected, and its dimensions are 300 mm×180 mm×250 mm (length×width×height).

[0065] In order to ensure the mesh quality and the accuracy of the simulation results, a thinned air domain 103 is set outside the electromagnet unit 2 and the circumferential SH waveguide unit 3. At the same time, in order to avoid the interference of boundary reflection, low reflection boundaries are set at the cross sections on both sides of the casing to be inspected, and a point P is set on the inner wall surface of the casing to be inspected at a position 90° from the center of the circumferential SH waveguide unit 3 as the receiving point of the waveguide signal.

[0066] At this time, the magnetic flux density distribution of the static magnetic field generated by a single electromagnet unit 2 is as follows: Fig.11 As shown in the figure, it can be seen from the direction of the arrows on the surface that the electromagnet unit 2 generates a static magnetic field along the radial direction of the pipeline and enters the casing 100 to be inspected through the circumferential SH waveguide unit 3, and then gradually diffuses to both sides along the circumference of the casing 100 to be inspected. This shows that the electromagnet unit 2 can provide the circumferential SH waveguide unit 3 with a static bias magnetic field along the casing radial direction and perpendicular to the circumferential SH waveguide unit 3.

[0067] When a 5-cycle Hanning window modulated sinusoidal signal with a center frequency of 103 kHz is further introduced into the eddy current winding coil 7, a circumferential SH0 modal guided wave propagating to both sides along the circumference of the casing can be excited under the action of the bias magnetic field. Fig.12 This is a snapshot of the x-direction displacement field of the axial section at 42.5 μs. Fig.12 It can be seen that at different positions in the wave propagation direction, the displacement direction and size of the particles throughout the thickness of the casing to be inspected remain consistent, which conforms to the typical circumferential SH0 mode guided wave displacement distribution characteristics.

[0068] In addition, the time domain waveform of the x-direction displacement of point P can be extracted by referring to the following: Fig.13 As shown. By using the time-of-flight method, it can be calculated that the arrival time of the wave packet is 55.8μs, and the corresponding actual group velocity is 2869.89m / s; this value is close to the theoretical group velocity (3102m / s) of the circumferential SH0 mode guided wave at 103kHz, with a relative error of 7.48%. Therefore, it can be further verified that the guided wave excited in this case is the circumferential SH0 mode guided wave.

[0069] Of course, the present invention is not limited to the excitation of circumferential SH0 modal waveguides. By changing the center frequency and time domain period number of the excitation signal, as well as the width, spacing and spatial period number (quantity) of the inner core 8 in the circumferential SH waveguide unit 3, it is also possible to excite circumferential SH waveguides of other modes.

[0070] In addition, the simulation model of the circumferential A0 mode guided wave excited in the casing to be inspected is established as follows Fig.14As shown, it includes two groups of electromagnet units 2 and two groups of circumferential SH waveguide units 3 (center interval 60°), and a group of circumferential A0 modal waveguide units 4 (located in the center area of ​​the two groups of electromagnet units 2). The size parameters of each structure are as follows:

[0071] The size of the casing 100 to be inspected is 9.5 mm×204 mm×80 mm (thickness×inner diameter×length); the wire diameter of the circumferential A0 mode waveguide unit 4 is 0.2 mm, the number of turns is 6, and the number of layers is a single layer. Figure 1 The marked d is 1.2mm, g is 30mm (consistent with the length of the annular magnetizer 1), and e is 9.2mm (need to ensure consistency with the half wavelength of the circumferential A0 mode waveguide); the rectangular air domain and the casing to be inspected are located at the same center, and its size is 300mm×120mm×250mm (length×width×height). In addition, the size parameters of the annular magnetizer 1, the electromagnet unit 2, and the circumferential SH waveguide unit 3 are all the same Fig.10 Keep it consistent.

[0072] In order to ensure the mesh quality and the accuracy of the simulation results, a refined air domain 103 and a skin layer refined region 104 are respectively set on the inner wall of the casing 100 to be inspected above and directly below the circumferential A0 mode waveguide unit 4, as shown in FIG. Fig.14 At the same time, in order to avoid the interference of boundary reflection, low reflection boundaries are set at the cross sections on both sides of the casing to be inspected, and point Q is set on the inner wall surface of the casing to be inspected 100 at a position 90° away from the center of the circumferential A0 modal waveguide unit 4 as the receiving point of the waveguide signal.

[0073] The magnetic flux density distribution results of the static magnetic field generated by two sets of adjacent electromagnet units 2 are as follows: Fig.15 As shown, it can be seen from the direction of the arrows on the surface that the static bias magnetic field generated by the two groups of electromagnet units 2 can form a magnetic circuit at the electromagnet units 2 and the casing 100 to be inspected and the annular magnetic conductor 1 therebetween, thereby providing the circumferential A0 modal waveguide unit 4 with a static bias magnetic field with high intensity along the circumference of the casing.

[0074] Ensure that the current directions in each unit coil along the circumferential direction of the circumferential A0 modal waveguide unit 4 are opposite, and a 5-cycle Hanning window modulated sinusoidal signal with a center frequency of 129kHz is introduced therein. Under the action of the circumferential bias magnetic field, the circumferential A0 modal waveguide can be stimulated to propagate to both sides along the circumference of the casing at the same time. Fig.16 This is a snapshot of the displacement field in the y direction of the axial cross section at 72μs. The "deformation" setting is added to the y direction displacement in the result, making it easier to observe the vibration direction of the particle. Fig.16It can be seen that at this moment, the centers of the wave packets are located at the 0° and 180° positions of the casing respectively, and the results of the y-direction displacement display are consistent with the displacement distribution characteristics of the typical circumferential A0 mode guided wave (i.e., bending wave).

[0075] In addition, the time domain waveform of the y-direction displacement of the Q point position can be extracted by referring to the following: Fig.17 As shown. By using the time-of-flight method, it can be calculated that the arrival time of the wave packet is 50.47μs, and the corresponding actual group velocity is 3172.97m / s; this value is very close to the theoretical group velocity (3113m / s) of the circumferential A0 mode guided wave at 129kHz, with a relative error of only 1.93%. Therefore, it can be further verified that the guided wave excited in this case is the circumferential A0 mode guided wave.

[0076] The present invention provides a dual-type waveguide integrated acoustic logging system for cementing quality detection, comprising: an annular magnetic conductor, a plurality of electromagnet units, a plurality of circumferential SH waveguide units, and a plurality of circumferential A0 modal waveguide units. The electromagnet unit is composed of a magnetic core and an excitation coil, and the excitation coil is evenly wound around the periphery of the magnetic core; the circumferential SH waveguide unit is composed of a plurality of inner cores and a plurality of eddy current winding coils, each inner core is evenly wound with a section of eddy current winding coil, and the plurality of eddy current winding coils are connected in series.

[0077] The dual-type waveguide integrated acoustic logging system with the above structural features has at least the following beneficial effects compared with the prior art:

[0078] 1) In the integrated acoustic logging system provided by the present invention, the circumferential SH waveguide unit and the circumferential A0 mode waveguide unit are always kept at the same circumferential position inside the casing to be inspected during the inspection process, so that the two types of waveguides have the same circumferential initial conditions, thereby providing help to ensure the accuracy of cementing quality inspection results;

[0079] 2) The integrated acoustic wave logging system provided by the present invention integrates the circumferential SH waveguide unit and the circumferential A0 modal waveguide unit so that the electromagnetic acoustic transducer structure can respectively realize the excitation and reception of the circumferential SH waveguide and the circumferential A0 modal waveguide, which helps to simplify the cementing quality detection process and improve the cementing quality detection efficiency;

[0080] 3) The integrated acoustic logging system provided by the present invention uses an electromagnet unit to generate a static bias magnetic field, which fundamentally solves a series of problems in the prior art electromagnetic acoustic transducer, such as difficulty in movement and probe wear caused by adsorption of iron filings during the mobile detection process in the casing.

[0081] The above is only a specific embodiment 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, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A dual-type waveguide integrated acoustic logging system for cementing quality detection, characterized in that: Included are: Ring-shaped magnetic conductor; A plurality of electromagnet units; the electromagnet units are arranged at equal intervals along the circumferential direction of the casing to be inspected on the annular outer side of the annular magnetic conductor; wherein the electromagnet units are composed of a magnetic core and an excitation coil, the axial direction of the magnetic core is arranged along a direction perpendicular to the tangential direction of the annular magnetic conductor, and the excitation coil is evenly wound around the periphery of the magnetic core; A plurality of circumferential SH waveguide units; the circumferential SH waveguide units are arranged in one-to-one correspondence with the electromagnet units; the circumferential SH waveguide units are composed of a plurality of inner cores and a plurality of sections of eddy current winding coils; wherein the plurality of inner cores of the same circumferential SH waveguide unit are arranged side by side at equal intervals and between the magnetic core and the inner wall of the casing to be inspected, and the length direction of the inner core is parallel to the axial direction of the casing to be inspected; a section of eddy current winding coil is evenly wound on each inner core, and the plurality of sections of eddy current winding coils are connected in series; A plurality of circumferential A0 modal waveguide units; the circumferential A0 modal waveguide units are arranged on the inner wall of the casing to be inspected at the middle position of adjacent electromagnet units; wherein the length direction of the circumferential A0 modal waveguide units is parallel to the axial direction of the casing to be inspected, and the circumferential A0 modal waveguide units and the annular magnetic conductor are located in the same circumferential direction of the casing to be inspected.

2. A dual-type waveguide integrated acoustic logging system for cementing quality detection according to claim 1, characterized in that: The annular magnetic conductor is coaxially arranged with the casing to be inspected, and the material thereof is selected to be a magnetic and non-conductive ferrite.

3. A dual-type waveguide integrated acoustic logging system for cementing quality detection according to claim 1, characterized in that: The number of electromagnet units provided is six groups; Adjacent electromagnet units are arranged at an angle of 60°, and the directions of the static bias magnetic fields provided by adjacent electromagnet units and distributed along the radial direction of the casing to be inspected are opposite.

4. A dual-type waveguide integrated acoustic logging system for cementing quality detection according to claim 1, characterized in that: In the same circumferential SH waveguide unit, the current directions of the eddy current winding coils wound on adjacent inner cores arranged side by side with equal intervals are arranged in opposite directions.

5. A dual-type waveguide integrated acoustic logging system for cementing quality detection according to claim 4, characterized in that: The width of any inner core in the circumferential SH waveguide unit plus the interval between adjacent inner cores arranged side by side at equal intervals is equal to half the wavelength of the circumferential SH waveguide excited by the circumferential SH waveguide unit.

6. A dual-type waveguide integrated acoustic logging system for cementing quality detection according to claim 1, characterized in that: The circumferential A0 modal waveguide unit is made of flexible PCB material; wherein the center distance between two straight line segments in the circumferential A0 modal waveguide unit is equal to half the wavelength of the circumferential A0 modal waveguide wavelength excited by the circumferential A0 modal waveguide unit.

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