A method and device for measuring the inner diameter of a casing based on ultrasonic lamb waves

Abstract

The application discloses a casing inner diameter measurement method and device based on ultrasonic Lamb waves. A plurality of ultrasonic transducer strips distributed circumferentially on a logging instrument emit oblique incidence ultrasonic Lamb waves to the inner wall of the casing in the corresponding sector and synchronously collect time domain waveform signals returned by each sector, from which a first reflection wave arrival time is extracted; the propagation speed of the Lamb wave in the casing wall is obtained according to a mud sound speed value and a preset inclination angle of the ultrasonic transducer; the one-way propagation distance of the ultrasonic Lamb wave in the mud is obtained through the geometric relationship of the propagation path of the ultrasonic Lamb wave in the mud and the casing, the first reflection wave arrival time and the propagation speed, and the vertical distance from the surface of the ultrasonic transducer corresponding to the sector to the inner wall of the casing is calculated; based on the known outer diameter of the logging instrument, the casing inner diameter values in different directions are calculated, and the average casing inner diameter value is obtained through the casing inner diameter values. The scheme of the application can solve the application limitation of the traditional contact type measurement method in complex well conditions.

Description

Technical Field

[0001] This invention relates to the field of oil and gas exploration technology, and in particular to a method and apparatus for measuring casing inner diameter based on ultrasonic Lamb waves. Background Technology

[0002] In the process of oil exploration and development, oil and gas well casing is used to ensure safe oil and gas production by isolating the wellbore from the formation. The inner diameter of the casing is a key parameter of the casing's health status. It is the basis for assessing the degree of casing damage such as deformation, corrosion, and rupture, and directly determines the scientific validity and feasibility of well workover plans. It is an important technical link for timely detection of wellbore safety hazards, extending the service life of oil and gas wells, and ensuring stable and high production in oil and gas fields.

[0003] Currently, the industry commonly uses multi-arm caliper tools to measure casing inner diameter. Measurement is achieved through physical contact between the robotic arm and the casing inner wall. However, this method is prone to scratching the casing inner wall during measurement, exacerbating the risk of subsequent corrosion. When the casing is severely deformed or has deposits such as scale, wax, or silt adhering to its inner wall, the robotic arm is prone to jamming, leading to measurement interruptions and data distortion. Furthermore, in oil-based mud environments, the friction between the robotic arm and the casing inner wall is significantly reduced, making slippage more likely and further affecting the accuracy and reliability of the measurement results.

[0004] Therefore, a new method for measuring casing inner diameter is needed to overcome the limitations of traditional contact measurement methods in complex well conditions. Summary of the Invention

[0005] This invention provides a method and apparatus for measuring casing inner diameter based on ultrasonic Lamb waves, in order to overcome the limitations of traditional contact measurement methods in complex well conditions.

[0006] According to one aspect of the present invention, a method for measuring the inner diameter of a cannula based on ultrasonic Lamb waves is provided, comprising:

[0007] During the process of the logging instrument moving at a constant speed along the wellbore axis, multiple ultrasonic transducer strips distributed circumferentially on the logging instrument emit obliquely incident ultrasonic Lamb waves to the inner wall of the casing of the corresponding sector, and simultaneously collect the time-domain waveform signals of the ultrasonic Lamb waves returned from each sector. The arrival time of the first reflected wave, which characterizes the arrival time of the first reflected wave of the ultrasonic Lamb wave, is extracted from the time-domain waveform signals.

[0008] The propagation speed of ultrasonic Lamb waves in the casing wall is obtained based on the real-time measurement of the mud velocity in the current well section by the mud transducer and the preset tilt angle of the ultrasonic transducer.

[0009] For each sector, the one-way propagation distance of the ultrasonic Lamb wave in the mud is obtained by using the geometric relationship of the propagation path of the ultrasonic Lamb wave in the mud and the casing, as well as the arrival time of the first reflected wave and the propagation speed. Based on the preset tilt angle of the ultrasonic transducer, the vertical distance from the surface of the ultrasonic transducer to the inner wall of the casing corresponding to that sector is calculated.

[0010] Based on the vertical distance from the ultrasonic transducer surface to the inner wall of the casing for all sectors, and the known outer diameter of the logging instrument, the inner diameter values ​​of the casing in different orientations are calculated, and the average inner diameter value of the casing is obtained through each inner diameter value.

[0011] Optionally, the ultrasonic transducer has a six-sector distribution structure, with six independent ultrasonic transducer strips evenly distributed in the circumferential direction of the logging instrument. Each ultrasonic transducer strip includes a transmitting transducer and a receiving transducer. The center line connecting the transmitting transducer and the receiving transducer is parallel to the axis of the logging instrument, and both have the same tilt angle.

[0012] Optionally, the casing inner diameter values ​​at different orientations are calculated, and the average casing inner diameter value at that depth point is obtained from each of the casing inner diameter values, including:

[0013] The vertical distances from the transducer surface to the inner wall of the bushing, measured in pairs according to their relative positions, are used to calculate the inner diameter values ​​of the bushing in three orthogonal orientations. The calculation formula is as follows:

[0014] ;

[0015] in: , and D represents the inner diameter of the sleeve in three directions; D represents the outer diameter of the instrument. - The vertical distance from the surface of the ultrasonic transducer to the inner wall of the sleeve corresponding to the 6 sectors;

[0016] The average casing inner diameter value ID is calculated using the following formula:

[0017] .

[0018] Optionally, after synchronously acquiring the ultrasonic Lamb wave time-domain waveform signals returned from each sector, the method further includes:

[0019] The acquired raw time-domain waveform signal is subjected to DC offset correction to remove the baseline offset component caused by DC drift of the instrument circuit and correct the waveform baseline to zero level.

[0020] Filter out low-frequency pulsating noise of well fluid below the lower cutoff frequency and high-frequency electromagnetic interference of instrument circuits above the upper cutoff frequency, retaining only the effective signal frequency band where the first reflection of the Lamb wave is located;

[0021] The waveform acquisition time window is divided into multiple continuous time segments. A corresponding incremental gain coefficient is applied to the waveform signal in each segment to compensate for the distance-dependent energy attenuation caused by the propagation of ultrasonic Lamb waves in the mud medium and casing wall. The waveform signal after gain compensation is then smoothed.

[0022] Optionally, for each sector, the one-way propagation distance of the ultrasonic Lamb wave in the mud is obtained by using the geometric relationship of the propagation path of the ultrasonic Lamb wave in the mud and casing, as well as the arrival time of the first reflected wave and the propagation speed, including:

[0023] Based on the geometric relationship of the propagation path of the ultrasonic Lamb wave in the mud and casing, and the arrival time of the first reflected wave and the propagation speed of the sound, a system of two linear equations in two variables is established, wherein the two unknowns are the one-way propagation distance of the sound wave in the mud and the propagation distance in the casing wall; solving the system of two linear equations in two variables yields the one-way propagation distance of the ultrasonic Lamb wave in the mud; the system of two linear equations in two variables includes:

[0024] ;

[0025] ;

[0026] in, The receiver-source distance between the transmitting transducer and the receiving transducer. This represents the one-way propagation distance of the ultrasonic Lamb wave in the mud. This represents the propagation distance of the ultrasonic Lamb wave within the cannula wall. The preset tilt angle for the ultrasonic transducer. When the first reflected wave arrives, The value of the sound velocity in the mud. Let be the speed of sound propagation.

[0027] Optionally, calculating the vertical distance from the surface of the ultrasonic transducer to the inner wall of the sleeve corresponding to the sector based on the tilt angle of the ultrasonic transducer includes:

[0028] The vertical distance from the surface of the ultrasonic transducer to the inner wall of the sleeve is calculated using the following formula:

[0029] ;

[0030] in, The vertical distance from the surface of the ultrasonic transducer to the inner wall of the sleeve is denoted as . This represents the propagation distance of the ultrasonic Lamb wave within the cannula wall. The preset tilt angle for the ultrasonic transducer.

[0031] Optionally, extracting the arrival time of the first reflected wave, which characterizes the arrival time of the first reflected wave of the ultrasonic Lamb wave, from the time-domain waveform signal includes:

[0032] Based on the nominal inner diameter of the casing in the current well section, the outer diameter of the logging instrument, the mud velocity, and the tilt angle of the ultrasonic transducer, the theoretical arrival time range of the first reflection of the Lamb wave is calculated.

[0033] Within the theoretical arrival time range, identify the peak point with the largest amplitude in the time-domain waveform signal, and record the time corresponding to the peak point as the arrival time of the first reflected wave.

[0034] Taking the arrival time of the first reflected wave as the center, waveform segments of a preset number of periods before and after are extracted as the signal to be matched. These segments are then subjected to normalized cross-correlation with a pre-calibrated standard Lamb wave first reflected wave template to obtain a cross-correlation function curve. The maximum peak point of the cross-correlation function curve is determined, and the time corresponding to the maximum peak point is the arrival time of the first reflected wave.

[0035] According to another aspect of the present invention, a cannula inner diameter measuring device based on ultrasonic Lamb waves is provided, comprising:

[0036] The first reflected wave arrival time extraction unit is used to emit obliquely incident ultrasonic Lamb waves to the inner wall of the casing of the corresponding sector through multiple ultrasonic transducer strips distributed circumferentially on the logging instrument during the uniform movement of the logging instrument along the wellbore axis, and simultaneously collect the time domain waveform signal of the ultrasonic Lamb wave returned from each sector, and extract the first reflected wave arrival time, which represents the arrival time of the first reflected wave of the ultrasonic Lamb wave, from the time domain waveform signal.

[0037] The propagation velocity determination unit is used to obtain the propagation velocity of ultrasonic Lamb waves in the casing wall based on the mud velocity value in the current well section measured in real time by the mud transducer and the preset tilt angle of the ultrasonic transducer.

[0038] The vertical distance determination unit is used to determine the one-way propagation distance of the ultrasonic Lamb wave in the mud by using the geometric relationship of the propagation path of the ultrasonic Lamb wave in the mud and the casing, as well as the arrival time of the first reflected wave and the propagation speed for each sector. Based on the preset tilt angle of the ultrasonic transducer, the vertical distance from the surface of the ultrasonic transducer to the inner wall of the casing corresponding to the sector is calculated.

[0039] The average casing inner diameter value determination unit is used to calculate the casing inner diameter value at different orientations based on the vertical distance from the ultrasonic transducer surface to the inner wall of the casing corresponding to all sectors and the known outer diameter of the logging instrument, and obtain the average casing inner diameter value at that depth point through each of the casing inner diameter values.

[0040] According to another aspect of the present invention, an electronic device is provided, the electronic device comprising:

[0041] At least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores a computer program executable by the at least one processor, the computer program being executed by the at least one processor to enable the at least one processor to perform the ultrasonic Lamb wave-based cannula inner diameter measurement method according to any embodiment of the present invention.

[0042] According to another aspect of the present invention, a computer-readable storage medium is provided, the computer-readable storage medium storing computer instructions for causing a processor to execute and implement the sleeve inner diameter measurement method based on ultrasonic Lamb wave as described in any embodiment of the present invention.

[0043] According to another aspect of the present invention, a computer program product is provided, the computer program product comprising a computer program that, when executed by a processor, implements the method for measuring the inner diameter of a sleeve based on ultrasonic Lamb waves as described in any embodiment of the present invention.

[0044] The technical solution of this invention involves real-time acquisition of ultrasonic Lamb wave signals from multiple sectors during wellbore measurement using an ultrasonic transducer, and measurement of mud sound velocity using a mud transducer. At different formation depths, when an interface reflection wave arrives from the ultrasonic Lamb wave time-domain waveform signal, the ultrasonic Lamb wave velocity is calculated based on the mud sound velocity and the tilt angle of the ultrasonic transducer. When a first reflection wave arrives from the ultrasonic Lamb wave time-domain waveform data, a system of equations is established using the geometric relationship of the sound wave propagation path. The distance the sound wave travels in the mud is then solved, and the distance from the transducer surface to the casing inner wall in each sector is calculated. This yields the casing inner diameter and average inner diameter in multiple orientations. The method can stably measure the casing inner diameter in both water-based and oil-based mud environments, without being limited by a specific medium, and is adaptable to more complex well conditions. Furthermore, this invention employs non-contact measurement, avoiding inner wall damage and jamming risks, thus overcoming the limitations of traditional contact measurement methods in complex well conditions.

[0045] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0046] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0047] Figure 1 This is a flowchart of a sleeve inner diameter measurement method based on ultrasonic Lamb wave provided by an embodiment of the present invention;

[0048] Figure 2 This is a schematic diagram of an ultrasonic Lamb wave time-domain waveform signal applicable to an embodiment of the present invention;

[0049] Figure 3 This is a schematic diagram illustrating the measurement principle of a single ultrasonic transducer strip applicable to an embodiment of the present invention.

[0050] Figure 4 This is a schematic diagram of a six-sector instrument for measuring the inner diameter of a sleeve, applicable to an embodiment of the present invention.

[0051] Figure 5 This is a comparative diagram of the calculation results of the inner diameter of the sleeve applicable to an embodiment of the present invention;

[0052] Figure 6 This is a schematic diagram of the structure of a sleeve inner diameter measuring device based on ultrasonic Lamb wave provided in an embodiment of the present invention;

[0053] Figure 7 This is a schematic diagram of the structure of an electronic device that implements the ultrasonic Lamb wave-based sleeve inner diameter method according to embodiments of the present invention. Detailed Implementation

[0054] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0055] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0056] Figure 1 This is a flowchart illustrating a casing inner diameter measurement method based on ultrasonic Lamb waves, provided by an embodiment of the present invention. This embodiment is applicable to measuring the casing inner diameter of oil and gas well casings. The method can be executed by an ultrasonic Lamb wave-based casing inner diameter measuring device, which can be implemented in hardware and / or software and can be configured in an electronic device. Figure 1 As shown, the method includes:

[0057] S110. During the process of the logging instrument moving at a constant speed along the wellbore axis, multiple ultrasonic transducer strips distributed circumferentially on the logging instrument emit obliquely incident ultrasonic Lamb waves to the inner wall of the casing of the corresponding sector, and simultaneously collect the time-domain waveform signal of the ultrasonic Lamb wave returned from each sector. The arrival time of the first reflected wave, which characterizes the arrival time of the first reflected wave of the ultrasonic Lamb wave, is extracted from the time-domain waveform signal.

[0058] Specifically, when measuring the casing inner diameter throughout the well, the logging instrument moves downwards or upwards along the wellbore axis at a constant speed. The instrument's movement speed is typically matched to the sampling frequency of the ultrasonic transducers, ensuring that the sampling interval between adjacent depth points meets the measurement accuracy requirements stipulated by industry standards. Multiple ultrasonic transducer strips are evenly distributed around the circumference of the logging instrument, each strip corresponding to an independent measurement sector, achieving 360° coverage of the casing circumference. Each transducer strip contains a transmitting transducer and a receiving transducer, and each strip operates independently, capable of simultaneously acquiring casing geometry information from different orientations. The ultrasonic transducers emit ultrasonic waves at a preset tilt angle towards the casing inner wall of the corresponding sector. When the ultrasonic waves are incident on the casing wall at a specific tilt angle, they generate Lamb waves that propagate circumferentially within the casing wall. Each transducer strip independently acquires the reflected waveform of its corresponding sector, recording the time-domain response characteristics of the Lamb waves after propagation in the mud medium and casing wall, including the arrival time, amplitude, and phase of the reflected waves. A single reflected wave refers to the waveform signal of an ultrasonic wave emitted by a transmitting transducer that propagates through the mud to the inner wall of the casing, undergoes a single specular reflection, and returns to the receiving transducer. Its propagation path includes the round-trip distance of the sound wave in the mud and the propagation distance in the casing wall, which corresponds to the vertical distance from the transducer surface to the inner wall of the casing.

[0059] Figure 2 This is a schematic diagram of an ultrasonic Lamb wave time-domain waveform signal applicable to an embodiment of the present invention, as shown below. Figure 2 As shown, after different times, primary and secondary reflected waves can be collected. Among them, the primary reflected wave is the information that needs to be extracted.

[0060] S120. Based on the real-time measurement of the mud velocity in the wellbore of the current well section by the mud transducer and the preset tilt angle of the ultrasonic transducer, the propagation velocity of the ultrasonic Lamb wave in the casing wall is obtained.

[0061] Specifically, the mud transducer is typically installed in the unobstructed area above the logging instrument, directly contacting the mud inside the wellbore. It calculates the actual sound velocity of the mud in the current well section by emitting and receiving vertically incident ultrasonic pulses. The preset tilt angle refers to the fixed angle between the normal to the transducer's emitting surface and the radial perpendicular of the instrument. Only when ultrasonic waves are incident on the casing wall at a specific angle can the critical angle condition of Snell's law of refraction be satisfied, exciting a concentrated and stable Lamb wave main mode within the casing wall. In this embodiment of the invention, the preset tilt angle is typically set within the range of 30° to 45°. This range ensures effective Lamb wave excitation in standard casings of different steel grades and wall thicknesses, while achieving the highest signal-to-noise ratio. The propagation speed of the Lamb wave within the casing wall is derived from Snell's law of refraction, based on real-time measured mud sound velocity and the known preset tilt angle of the transducer. According to the law of refraction, when an ultrasonic wave is incident at the interface between two media at a critical angle, the refracted wave will propagate along the interface. At this time, the refraction angle is 90°. From this, the quantitative relationship between the Lamb wave velocity, the mud velocity, and the transducer tilt angle can be derived. No additional hardware equipment is required, nor is it necessary to pre-calibrate the acoustic parameters of the casing wall. The Lamb wave velocity can be solved using existing measurement data without changing the existing cementing quality testing instrument hardware structure.

[0062] S130. For each sector, the one-way propagation distance of the ultrasonic Lamb wave in the mud is obtained by using the geometric relationship of the propagation path of the ultrasonic Lamb wave in the mud and the casing, as well as the arrival time and propagation speed of the first reflected wave. Based on the preset tilt angle of the ultrasonic transducer, the vertical distance from the surface of the ultrasonic transducer to the inner wall of the casing corresponding to that sector is calculated.

[0063] The geometric relationship of the sound wave propagation path is established based on a single-strip measurement model. This model characterizes the process where ultrasonic waves emitted by the transmitting transducer are incident on the inner wall of the casing through mud, generate Lamb waves that propagate along the casing wall, and are then reflected back to the receiving transducer through the mud. The geometric relationship is used to decompose the total sound wave propagation path into a round-trip propagation segment in the mud and a horizontal propagation segment in the casing wall. Constraints between the propagation distances of each segment are established using known instrument structural parameters (receiver-source distance, transducer tilt angle). The single-pass propagation distance in the mud is the oblique propagation distance of the sound wave, while the calculation of the casing inner diameter requires the vertical distance from the transducer surface to the inner wall of the casing. Therefore, this vertical distance needs to be obtained through geometric transformation. Based on the side-angle relationship of a right triangle, with the single-pass propagation distance in the mud as the hypotenuse and the transducer tilt angle as the included angle, the vertical distance is calculated using a cosine function. This vertical distance is a parameter characterizing the relative position of the casing and the instrument in this sector, and it is also an input parameter for calculating the casing inner diameter in different orientations. Its calculation accuracy determines the measurement accuracy of the casing inner diameter.

[0064] S140. Based on the vertical distance from the ultrasonic transducer surface to the inner wall of the casing for all sectors, and the known outer diameter of the logging instrument, calculate the inner diameter of the casing at different orientations, and obtain the average inner diameter of the casing at that depth point through the inner diameter values ​​of each casing.

[0065] Specifically, as mentioned earlier, the vertical distance corresponding to each sector represents the shortest distance between the instrument surface and the inner wall of the casing for a circumferential sector. This distance describes the geometric changes of the casing in different orientations, whether it's uniform wall corrosion or localized deformation, depressions, or protrusions, all of which can be reflected by the differences in distance values ​​between sectors. The outer diameter of the logging instrument is a fixed structural parameter calibrated before the instrument leaves the factory and remains constant throughout the logging operation. The physical essence of the casing inner diameter is the diameter of the circle enclosed by the inner wall of the casing. Since the logging instrument is placed approximately in the center of the wellbore, the sum of the vertical distances from the instrument to the inner wall of the casing in any two relative orientations, plus the outer diameter of the instrument itself, equals the casing inner diameter at that orientation. The calibration accuracy of the instrument's outer diameter directly determines the systematic error in the casing inner diameter measurement. Therefore, the instrument must be calibrated regularly before use to ensure its values ​​are accurate and reliable. The casing inner diameter values ​​at different azimuths are obtained by adding the vertical distance between two relatively distributed sectors to the instrument outer diameter. By calculating the inner diameter values ​​at multiple orthogonal azimuths, non-uniform casing damage conditions such as elliptical deformation, bending deformation, and localized pitting corrosion can be accurately identified. The average inner diameter value is used to assess the degree of uniform corrosion and overall wall thickness variation of the casing, providing a data basis for predicting the remaining life of oil and gas wells. Simultaneously, the difference between the inner diameter value at each azimuth and the average inner diameter value can be used to quantify the degree of casing deformation. When the deviation between the inner diameter at a certain azimuth and the average inner diameter exceeds a preset threshold, localized casing damage can be determined at that azimuth.

[0066] In this embodiment of the invention, the ultrasonic transducer has a six-sector distribution structure, with six independent ultrasonic transducer strips evenly distributed in the circumferential direction of the logging instrument. Each ultrasonic transducer strip includes a transmitting transducer and a receiving transducer. The center line connecting the transmitting transducer and the receiving transducer is parallel to the axis of the logging instrument, and both have the same tilt angle.

[0067] Specifically, six independent strips are evenly arranged at 60° intervals around the instrument's circumference, enabling 360° full coverage measurement of the casing's inner wall. Compared to designs with fewer sectors, six sectors can capture the fine details of non-uniform casing damage such as elliptical deformation, localized pitting corrosion, and axial cracks at a reasonable hardware cost. Compared to designs with eight or more sectors, six sectors significantly reduce the complexity of the instrument's circuitry and the amount of data processing required, while simultaneously meeting the petroleum industry's azimuth resolution requirements for casing inner diameter measurement. Each strip operates independently without interference, allowing for parallel signal transmission and acquisition, ensuring the synchronization and real-time nature of the full circumferential measurement.

[0068] The transmitting transducer converts electrical signals into ultrasonic signals, which are then emitted at a preset angle towards the inner wall of the sleeve to generate Lamb waves. The receiving transducer is specifically responsible for converting the ultrasonic signals, after reflection and propagation through the sleeve, back into electrical signals for circuit acquisition and processing. This separate transmitting and receiving design optimizes the excitation efficiency of the transmitting transducer and the sensitivity of the receiving transducer, avoiding the signal crosstalk problem present in integrated transmitting and receiving designs, and effectively improving the signal-to-noise ratio of the original waveform signal.

[0069] The geometric design, with the line connecting the centers of the transmitting and receiving transducers parallel to the instrument axis, ensures the planar symmetry of the sound wave propagation path, allowing the Lamb wave to propagate circumferentially within the casing wall, perpendicular to the instrument axis. When the line connecting their centers is parallel to the axis, the round-trip propagation path of the sound wave in the mud and its propagation path within the casing wall lie in the same plane perpendicular to the instrument axis, simplifying the solution to a two-dimensional geometric problem. If this line forms an angle with the axis, it introduces propagation errors in three-dimensional space, disrupting the established mathematical relationships of the two-variable equations and leading to deviations in the calculated casing inner diameter. The identical tilt angles of the transmitting and receiving transducers ensure that the angle at which the ultrasonic wave is incident on the casing inner wall is exactly the same as the angle reflected back to the receiving transducer, satisfying the geometric conditions for specular reflection and enabling the receiving transducer to receive the strongest reflected wave signal. Simultaneously, both the incident and reflected waves satisfy the critical angle condition of Snell's law of refraction, generating a stable Lamb wave of the same mode within the casing wall. If there is a difference in the tilt angle between the two, it will not only cause the reflected wave to deviate from the effective receiving range of the receiving transducer, resulting in a significant attenuation of the signal amplitude, but also cause the calculation of Lamb wave speed to lose its theoretical basis, ultimately leading to measurement failure.

[0070] Figure 3 This is a schematic diagram illustrating the measurement principle of a single ultrasonic transducer strip applicable to embodiments of the present invention. Figure 3 As shown, from left to right, the standard wellbore structure and logging instruments for oil and gas wells are: the leftmost element is the logging instrument placed centrally along the well axis; outside the instrument are, in order, the wellbore mud, casing, cement sheath, and formation. The casing is the object being measured; the cement sheath is used to fix the casing and isolate fluids from different formations; and the wellbore mud is the intermediate medium for sound wave propagation between the instrument and the casing. An independent mud transducer is installed on the upper part of the instrument to measure the sound velocity of the wellbore mud in the current well section in real time. The mud transducer calculates the actual sound velocity of the mud in the current well section by measuring the round-trip time of the ultrasonic wave over a known fixed distance L. .

[0071] The instrument contains a single-strip ultrasonic transducer unit in its center, comprising a transmitting transducer T and a receiving transducer R. The center line connecting the two transducers is parallel to the well axis and has the same preset tilt angle. The transmitting transducer T is responsible for converting electrical signals into ultrasonic signals, at a tilt angle. The ultrasonic wave is emitted towards the inner wall of the casing; the receiving transducer R is responsible for converting the ultrasonic echo signal, after being reflected and propagated through the casing, into an electrical signal. The vertical distance between their centers... The receiver distance is a fixed structural parameter calibrated before the instrument leaves the factory.

[0072] The complete propagation path of the sound wave is as follows: The transmitting transducer T is tilted at an angle... Ultrasonic waves are emitted into the inner wall of the casing, and the sound waves travel obliquely a distance in the wellbore mud. The incident wave, satisfying the critical angle condition of Snell's law of refraction, will then generate a Lamb wave propagating circumferentially within the casing wall. The Lamb wave travels a distance within the casing wall. Then, again at the same angle The refracted wave is reflected back into the wellbore mud; the refracted wave continues to propagate a distance in the mud. Subsequently, it is received by the receiving transducer R, forming a primary reflected wave signal used for calculation. D is the radius of the logging instrument, a known fixed structural parameter; It is the vertical distance from the surface of the ultrasonic transducer to the inner wall of the sleeve.

[0073] Figure 4 This is a schematic diagram of a six-sector instrument measuring the inner diameter of a sleeve, applicable to an embodiment of the present invention. Figure 4 As shown, the standard cross-sectional layered structure of an oil and gas well, from the center outwards, consists of: the centrally placed logging instrument, the mud annulus filling the wellbore, the casing to be inspected, the cement sheath used for cementing, and the outermost formation. Under normal operating conditions, the casing is a standard circle, and the instrument is approximately centered inside the casing. Six independent ultrasonic transducer strips are evenly distributed around the circumference of the instrument. Each transducer independently measures the vertical distance from the instrument surface at its corresponding azimuth to the inner wall of the casing. - .

[0074] In this embodiment of the invention, the inner diameter values ​​of the casing at different orientations are calculated, and the average inner diameter value of the casing at that depth point is obtained from each inner diameter value, including:

[0075] The vertical distances from the transducer surface to the inner wall of the bushing, measured in pairs according to their relative positions, are used to calculate the inner diameter values ​​of the bushing in three orthogonal orientations. The calculation formula is as follows:

[0076] ;

[0077] in: , and D represents the inner diameter of the sleeve in three directions; D represents the outer diameter of the instrument. - The vertical distance from the surface of the ultrasonic transducer to the inner wall of the sleeve corresponding to the 6 sectors;

[0078] The average casing inner diameter value ID is calculated using the following formula:

[0079] .

[0080] Specifically, as mentioned above, six sectors are evenly distributed around the circumference of the instrument at 60° intervals. The two sectors in opposite positions are located at the two ends of the instrument diameter. By pairing the six sectors in pairs according to their relative positions (1,4), (2,5), and (3,6), three mutually orthogonal measurement directions can be obtained, which characterize the geometry of the sleeve cross-section.

[0081] In the calculation formula, The inner diameter of the casing in the first orthogonal orientation. This represents the vertical distance from the logging instrument to the inner wall of the casing, measured in sector 1. The perpendicular distance measured in sector 4, opposite sector 1, is added to the instrument's outer diameter to obtain the straight-line distance between the inner walls of the sleeve in that orthogonal direction, which is the inner diameter of the sleeve at that location. This process continues in the same manner. The inner diameter of the sleeve in the second orthogonal orientation corresponds to the measurement results of sectors 2 and 5, obtained through... and calculate; The inner diameter of the casing in the third orthogonal orientation corresponds to the measurement results of sectors 3 and 6, obtained through... and calculate.

[0082] The average casing inner diameter at a given depth is obtained by arithmetically averaging the casing inner diameter values ​​from three orthogonal orientations. This average inner diameter eliminates random errors from measurements at a single orientation, objectively reflecting the overall average size of the casing at that depth, and is used to assess the uniformity of casing corrosion and overall wall thickness variation.

[0083] In this embodiment of the invention, after synchronously acquiring the ultrasonic Lamb wave time-domain waveform signals returned from each sector, the method further includes:

[0084] The acquired raw time-domain waveform signal is subjected to DC offset correction to remove the baseline offset component caused by DC drift of the instrument circuit and correct the waveform baseline to zero level.

[0085] Filter out low-frequency pulsating noise of well fluid below the lower cutoff frequency and high-frequency electromagnetic interference of instrument circuits above the upper cutoff frequency, retaining only the effective signal frequency band where the first reflection of the Lamb wave is located;

[0086] The waveform acquisition time window is divided into multiple continuous time segments. A corresponding incremental gain coefficient is applied to the waveform signal in each segment to compensate for the distance-dependent energy attenuation caused by the propagation of sound waves in the mud medium and casing wall. The waveform signal after gain compensation is then smoothed.

[0087] Specifically, DC offset correction is used to eliminate systematic baseline errors introduced by the instrument's analog circuitry. The original acquired ultrasonic Lamb wave signal will have a fixed DC component that deviates from zero level due to the temperature drift characteristics of the instrument's circuit components, power supply ripple interference, and the zero-point offset of the analog-to-digital conversion module, thus distorting the true amplitude of the reflected wave. By calculating the average DC value of the original waveform in the no-signal region and subtracting it from the entire waveform, the waveform baseline can be corrected to zero level.

[0088] Bandpass filters are used to remove interference noise in the logging field. Low-frequency noise below the lower cutoff frequency mainly originates from the flow pulsation of mud in the wellbore, mechanical vibration during instrument lowering, and low-frequency background noise from the formation, manifesting as slow fluctuations in the waveform baseline. High-frequency noise above the upper cutoff frequency mainly originates from electromagnetic radiation from the instrument circuitry, switching power supply noise, and random thermal noise, manifesting as dense spikes and glitches on the waveform. Based on the nominal center frequency of the ultrasonic transducer and the effective propagation bandwidth of the Lamb wave master mode, 4th-8th order Butterworth bandpass filters are set to maximize the removal of high and low frequency interference while preserving the waveform characteristics of the first reflected wave, thereby improving the waveform signal-to-noise ratio.

[0089] When sound waves propagate through mud and casing, their energy decays exponentially with increasing propagation distance. This results in later-arriving reflected waves having much lower amplitudes than earlier-arriving direct and interface waves, and may even be completely submerged by noise. Dividing the entire waveform acquisition time window into 3-5 consecutive time segments and applying a linearly increasing gain coefficient to each segment, based on the positive correlation between sound wave propagation time and energy attenuation, ensures that the amplitudes of reflected waves at different propagation distances are within a uniform, detectable range. Smoothing the gain-compensated waveform using a five-point cubic moving average algorithm further suppresses residual random white noise and pulse spike interference while preserving the steepness of the reflected wave leading edge and peak position characteristics.

[0090] In this embodiment of the invention, for each sector, the one-way propagation distance of the ultrasonic Lamb wave in the mud is obtained by using the geometric relationship of the propagation path of the ultrasonic Lamb wave in the mud and casing, as well as the arrival time and propagation speed of the first reflected wave, including:

[0091] Based on the geometric relationship of the propagation path of ultrasonic Lamb waves in mud and casing, and the arrival time and propagation speed of the first reflected wave, a system of two linear equations in two variables is established, containing two unknowns: the one-way propagation distance of the sound wave in the mud and the propagation distance in the casing wall. Solving the system of two linear equations yields the one-way propagation distance of the ultrasonic Lamb wave in the mud. The system of two linear equations includes:

[0092] ;

[0093] ;

[0094] in, The receiver-source distance between the transmitting transducer and the receiving transducer. This represents the one-way propagation distance of the ultrasonic Lamb wave in the mud. This represents the propagation distance of the ultrasonic Lamb wave within the cannula wall. The preset tilt angle for the ultrasonic transducer. When a reflected wave arrives, This represents the sound velocity of the mud. To propagate the speed of sound.

[0095] Specifically, since the total propagation path of the sound wave includes two media segments—mud and casing—there are two unknown propagation distance parameters, requiring two independent equations to solve. The first equation, based on the aforementioned propagation path geometry, describes the geometric constraints between the receiver-source distance and the one-way propagation distance in the mud and casing. The second equation, based on the fundamental laws of sound wave propagation, describes the time constraints between the total arrival time of the first reflected wave and the propagation time in the mud and casing. Solving these two sets of linear equations simultaneously yields the two parameters: the one-way propagation distance of the sound wave in the mud and the propagation distance in the casing wall. The one-way propagation distance in the mud reflects the oblique propagation distance of the sound wave from the transducer surface to the inner wall of the casing. The propagation distance in the casing wall is only used for solving the simultaneous equations and is not included in the calculation of the casing's inner diameter.

[0096] As mentioned above Figure 2 As shown, the model, from left to right, consists of instruments, wellbore mud, casing, cement, and formation. The tilt angle between the transmitting transducer T and the receiving transducer R on a single strip is... The distance between the receiver and the source is The propagation distance of sound waves in mud is twice that of sound waves. The propagation distance in the casing is According to geometric relationships:

[0097] ;

[0098] The velocity of sound in mud is obtained from a mud transducer, and the velocity of Lamb wave is calculated based on the law of refraction.

[0099] ;

[0100] in: The velocity of sound in mud; The speed of sound is Lamb wave.

[0101] The arrival time of the first reflected wave is obtained from the time-domain waveform of the ultrasonic Lamb wave. :

[0102] ;

[0103] Solving the system of two equations yields and .

[0104] In this embodiment of the invention, the vertical distance from the surface of the ultrasonic transducer to the inner wall of the sleeve corresponding to the sector is calculated based on the tilt angle of the ultrasonic transducer, including:

[0105] The vertical distance from the surface of the ultrasonic transducer to the inner wall of the sleeve is calculated using the following formula:

[0106] ;

[0107] in, This is the vertical distance from the surface of the ultrasonic transducer to the inner wall of the sleeve. This represents the propagation distance of the ultrasonic Lamb wave within the cannula wall. The preset tilt angle for the ultrasonic transducer.

[0108] Specifically, since the calculation of the sleeve's inner diameter requires the shortest vertical distance from the instrument surface to the sleeve's inner wall, rather than the oblique propagation distance of the sound wave, the vertical distance is obtained through this cosine function transformation. The conversion process only involves fixed angle parameters. It will not introduce additional measurement errors, therefore The accuracy of the calculation depends entirely on The accuracy of the solution. The accuracy of the solution is determined by both the accuracy of the extraction of the arrival time of the first reflected wave and the real-time measurement accuracy of the mud sound velocity. Errors in these two parameters are directly transmitted to the vertical distance. In the calculation results.

[0109] In this embodiment of the invention, extracting the arrival time of the first reflected wave, which characterizes the arrival time of the first reflected wave of the Lamb wave, from the time-domain waveform signal includes:

[0110] Based on the nominal inner diameter of the casing in the current well section, the outer diameter of the logging instrument, the mud velocity, and the tilt angle of the ultrasonic transducer, the theoretical arrival time range of the first reflection wave of the Lamb wave is calculated.

[0111] Within the theoretical arrival time range, identify the peak point with the largest amplitude in the time-domain waveform signal, and record the time corresponding to the peak point as the arrival time of the first reflected wave.

[0112] Taking the arrival time of the first reflected wave as the center, waveform segments of a preset number of periods before and after are extracted as the signals to be matched. These segments are then subjected to normalized cross-correlation with a pre-calibrated standard Lamb wave first reflected wave template to obtain the cross-correlation function curve. The maximum peak point of the cross-correlation function curve is identified, and the time corresponding to this peak point is the arrival time of the first reflected wave.

[0113] Specifically, the original acquired ultrasonic Lamb wave time-domain waveform contains various interference signals such as direct waves, casing secondary reflection waves, cement sheath interface waves, and formation waves. The arrival times of these signals differ significantly from those of the primary reflection wave. By substituting known parameters such as the nominal inner diameter of the casing, the outer diameter of the instrument, the real-time mud velocity, and the transducer tilt angle, and combining this with the acoustic wave propagation time equation, the theoretical minimum and maximum arrival times of the primary reflection wave can be calculated, forming a narrow-band effective extraction time window. This time window can compress the search range to the interval within which the primary reflection wave is bound to occur.

[0114] The first-arrival Lamb wave is a signal that returns directly to the receiving transducer after being reflected by the mirror surface of the inner wall of the sleeve. It has the shortest propagation path and the least energy attenuation, therefore it typically exhibits the largest amplitude peak within the theoretical arrival time range. By traversing all sampling points within the effective time window, the peak point with the largest amplitude is found, and its corresponding time is recorded, thus obtaining the initial arrival time of the first-arrival wave.

[0115] The standard Lamb wave first-reflection template is a clean waveform pre-calibrated in a standard laboratory environment, preserving the time-domain characteristics of the first-reflection wave. Waveform segments of 2-3 cycles before and after the initial arrival time are extracted as the signal to be matched. This covers the complete first-reflection wave waveform without introducing excessive background noise. Normalized cross-correlation calculation measures the waveform similarity between the signal to be matched and the standard template. The maximum peak of the output cross-correlation function curve corresponds to the moment when the two signals are most similar, which is the arrival time of the first-reflection wave. Even if the peak of the first-reflection wave is interfered with or submerged by noise, the accurate arrival time can still be found through overall waveform similarity matching, improving extraction accuracy.

[0116] Figure 5 This is a comparative diagram of the calculation results of the inner diameter of the casing applicable to an embodiment of the present invention, as shown in the figure. Figure 5As shown, the calculated inner diameter of a sleeve with an outer diameter of 9.625 inches is presented under three different thickness specifications. The actual inner diameters are 8.835, 8.681, and 8.535 inches, respectively. The transducer tilt angle is 35°, and the receiver-source distance is 0.25 m. The data points in the figure are distributed near the center 45° line, and the average relative error is 0.18%, indicating that ultrasonic Lamb wave ranging has good measurement accuracy.

[0117] Figure 6 This is a schematic diagram of a sleeve inner diameter measuring device based on ultrasonic Lamb waves provided in an embodiment of the present invention. Figure 6 As shown, the device includes:

[0118] The first reflected wave arrival time extraction unit 610 is used to emit obliquely incident ultrasonic Lamb waves to the inner wall of the casing of the corresponding sector through multiple ultrasonic transducer strips distributed circumferentially on the logging instrument during the uniform movement of the logging instrument along the wellbore axis, and simultaneously acquire the time domain waveform signal of the ultrasonic Lamb wave returned from each sector, and extract the first reflected wave arrival time, which represents the arrival time of the first reflected wave of the ultrasonic Lamb wave, from the time domain waveform signal.

[0119] The propagation velocity determination unit 620 is used to obtain the propagation velocity of ultrasonic Lamb waves in the casing wall based on the mud velocity value in the current well section measured in real time by the mud transducer and the preset tilt angle of the ultrasonic transducer.

[0120] The vertical distance determination unit 630 is used to determine the one-way propagation distance of the ultrasonic Lamb wave in the mud by using the geometric relationship of the propagation path of the ultrasonic Lamb wave in the mud and the casing, as well as the arrival time and propagation speed of the first reflected wave for each sector. Based on the preset tilt angle of the ultrasonic transducer, the vertical distance from the surface of the ultrasonic transducer to the inner wall of the casing corresponding to that sector is calculated.

[0121] The average casing inner diameter value determination unit 640 is used to calculate the casing inner diameter value in different orientations based on the vertical distance from the ultrasonic transducer surface to the inner wall of the casing corresponding to all sectors and the known outer diameter of the logging instrument, and obtain the average casing inner diameter value through each casing inner diameter value.

[0122] The cannula inner diameter measuring device based on ultrasonic Lamb wave provided in this embodiment of the invention can execute the cannula inner diameter measuring method based on ultrasonic Lamb wave provided in any embodiment of the invention, and has the corresponding functional modules and beneficial effects of the method.

[0123] Figure 7A schematic diagram of an electronic device 10, which can be used to implement embodiments of the present invention, is shown. The electronic device is intended to represent various forms of digital computers, such as laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device can also represent various forms of mobile devices, such as personal digital processors, cellular phones, smartphones, wearable devices (e.g., helmets, glasses, watches, etc.), and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely illustrative and are not intended to limit the implementation of the invention described and / or claimed herein.

[0124] like Figure 7 As shown, the electronic device 10 includes at least one processor 11 and a memory, such as a read-only memory (ROM) 12 or a random access memory (RAM) 13, communicatively connected to the at least one processor 11. The memory stores computer programs executable by the at least one processor. The processor 11 can perform various appropriate actions and processes based on the computer program stored in the ROM 12 or loaded from storage unit 18 into the RAM 13. The RAM 13 can also store various programs and data required for the operation of the electronic device 10. The processor 11, ROM 12, and RAM 13 are interconnected via a bus 14. An input / output (I / O) interface 15 is also connected to the bus 14.

[0125] Multiple components in electronic device 10 are connected to I / O interface 15, including: input unit 16, such as keyboard, mouse, etc.; output unit 17, such as various types of displays, speakers, etc.; storage unit 18, such as disk, optical disk, etc.; and communication unit 19, such as network card, modem, wireless transceiver, etc. Communication unit 19 allows electronic device 10 to exchange information / data with other devices through computer networks such as the Internet and / or various telecommunications networks.

[0126] Processor 11 can be a variety of general-purpose and / or special-purpose processing components with processing and computing capabilities. Some examples of processor 11 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various special-purpose artificial intelligence (AI) computing chips, various processors running machine learning model algorithms, a digital signal processor (DSP), and any suitable processor, controller, microcontroller, etc. Processor 11 performs the various methods and processes described above, such as the method for measuring the inner diameter of a sleeve based on ultrasonic Lamb waves.

[0127] In some embodiments, the ultrasonic Lamb wave-based cannula diameter measurement method can be implemented as a computer program tangibly contained in a computer-readable storage medium, such as storage unit 18. In some embodiments, part or all of the computer program can be loaded and / or mounted on electronic device 10 via ROM 12 and / or communication unit 19. When the computer program is loaded into RAM 13 and executed by processor 11, one or more steps of the ultrasonic Lamb wave-based cannula diameter measurement method described above can be performed. Alternatively, in other embodiments, processor 11 can be configured to perform the ultrasonic Lamb wave-based cannula diameter measurement method by any other suitable means (e.g., by means of firmware).

[0128] Various embodiments of the systems and techniques described above herein can be implemented in digital electronic circuit systems, integrated circuit systems, field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), application-specific standard products (ASSPs), systems-on-a-chip (SoCs), payload-programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various embodiments may include implementations in one or more computer programs that can be executed and / or interpreted on a programmable system including at least one programmable processor, which may be a dedicated or general-purpose programmable processor, capable of receiving data and instructions from a storage system, at least one input device, and at least one output device, and transmitting data and instructions to the storage system, the at least one input device, and the at least one output device.

[0129] Computer programs used to implement the methods of the present invention may be written in any combination of one or more programming languages. These computer programs may be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, such that when executed by the processor, the computer programs cause the functions / operations specified in the flowcharts and / or block diagrams to be performed. The computer programs may be executed entirely on a machine, partially on a machine, or as a standalone software package, partially on a machine and partially on a remote machine, or entirely on a remote machine or server.

[0130] In the context of this invention, a computer-readable storage medium can be a tangible medium that may contain or store a computer program for use by or in conjunction with an instruction execution system, apparatus, or device. A computer-readable storage medium may include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination thereof. Alternatively, a computer-readable storage medium may be a machine-readable signal medium. More specific examples of machine-readable storage media include electrical connections based on one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof.

[0131] To provide interaction with a user, the systems and techniques described herein can be implemented on an electronic device having: a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user; and a keyboard and pointing device (e.g., a mouse or trackball) through which the user provides input to the electronic device. Other types of devices can also be used to provide interaction with the user; for example, feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form (including sound input, voice input, or tactile input).

[0132] The systems and technologies described herein can be implemented in computing systems that include backend components (e.g., as data servers), or middleware components (e.g., application servers), or frontend components (e.g., user computers with graphical user interfaces or web browsers through which users can interact with implementations of the systems and technologies described herein), or any combination of such backend, middleware, or frontend components. The components of the system can be interconnected via digital data communication of any form or medium (e.g., communication networks). Examples of communication networks include local area networks (LANs), wide area networks (WANs), blockchain networks, and the Internet.

[0133] A computing system can include clients and servers. Clients and servers are generally located far apart and typically interact through communication networks. The client-server relationship is created by computer programs running on the respective computers and having a client-server relationship with each other. The server can be a cloud server, also known as a cloud computing server or cloud host, which is a hosting product within the cloud computing service system to address the shortcomings of traditional physical hosts and VPS services, such as high management difficulty and weak business scalability.

[0134] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0135] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for measuring the inner diameter of a sleeve based on ultrasonic Lamb waves, characterized in that, include: During the process of the logging instrument moving at a constant speed along the wellbore axis, multiple ultrasonic transducer strips distributed circumferentially on the logging instrument emit obliquely incident ultrasonic Lamb waves to the inner wall of the casing of the corresponding sector, and simultaneously collect the time-domain waveform signals of the ultrasonic Lamb waves returned from each sector. The arrival time of the first reflected wave, which characterizes the arrival time of the first reflected wave of the ultrasonic Lamb wave, is extracted from the time-domain waveform signals. The propagation velocity of ultrasonic Lamb waves in the casing wall is obtained by measuring the mud velocity in the current well section of the wellbore in real time using the mud transducer and the preset tilt angle of the ultrasonic transducer. For each sector, the one-way propagation distance of the ultrasonic Lamb wave in the mud is obtained by using the geometric relationship of the propagation path of the ultrasonic Lamb wave in the mud and the casing, as well as the arrival time of the first reflected wave and the propagation speed. Based on the preset tilt angle of the ultrasonic transducer, the vertical distance from the surface of the ultrasonic transducer to the inner wall of the casing corresponding to that sector is calculated. Based on the vertical distance from the ultrasonic transducer surface to the inner wall of the casing corresponding to all sectors, and based on the known outer diameter of the logging instrument, the inner diameter values ​​of the casing in different orientations are calculated, and the average inner diameter value of the casing is obtained through each inner diameter value of the casing. For each sector, the one-way propagation distance of the ultrasonic Lamb wave in the mud is obtained by using the geometric relationship of the propagation path of the ultrasonic Lamb wave in the mud and casing, as well as the arrival time of the first reflected wave and the propagation speed of the sound, including: Establish a system of two linear equations in two variables, where the two unknowns are the one-way propagation distance of the sound wave in the mud and the propagation distance in the casing wall; solve the system of two linear equations to obtain the one-way propagation distance of the ultrasonic Lamb wave in the mud; the system of two linear equations includes: ； ； in, The receiver-source distance between the transmitting transducer and the receiving transducer. This represents the one-way propagation distance of the ultrasonic Lamb wave in the mud. This represents the propagation distance of the ultrasonic Lamb wave within the cannula wall. The preset tilt angle for the ultrasonic transducer. When the first reflected wave arrives, The value of the sound velocity in the mud. Let be the speed of sound propagation.

2. The method according to claim 1, characterized in that, The ultrasonic transducer has a six-sector distribution structure, with six independent ultrasonic transducer strips evenly distributed around the circumference of the logging instrument. Each ultrasonic transducer strip includes a transmitting transducer and a receiving transducer. The line connecting the centers of the transmitting transducer and the receiving transducer is parallel to the axis of the logging instrument, and both have the same tilt angle.

3. The method according to claim 2, characterized in that, The casing inner diameter values ​​at different orientations are calculated, and the average casing inner diameter value at that depth point is obtained from each of these casing inner diameter values, including: The vertical distances from the transducer surface to the inner wall of the bushing, measured in pairs according to their relative positions, are used to calculate the inner diameter values ​​of the bushing in three orthogonal orientations. The calculation formula is as follows: ； in: , and D represents the inner diameter of the sleeve in three directions; D represents the outer diameter of the instrument. - The vertical distance from the surface of the ultrasonic transducer to the inner wall of the sleeve corresponding to the 6 sectors; The average casing inner diameter value ID is calculated using the following formula: 。 4. The method according to claim 2, characterized in that, After synchronously acquiring the ultrasonic Lamb wave time-domain waveform signals returned from each sector, the process also includes: The acquired raw time-domain waveform signal is subjected to DC offset correction to remove the baseline offset component caused by DC drift of the instrument circuit and correct the waveform baseline to zero level. Filter out low-frequency pulsating noise of well fluid below the lower cutoff frequency and high-frequency electromagnetic interference of instrument circuits above the upper cutoff frequency, retaining only the effective signal frequency band where the first reflection of the Lamb wave is located; The waveform acquisition time window is divided into multiple continuous time segments. A corresponding incremental gain coefficient is applied to the waveform signal in each segment to compensate for the distance-dependent energy attenuation caused by the propagation of ultrasonic Lamb waves in the mud medium and casing wall. The waveform signal after gain compensation is then smoothed.

5. The method according to claim 1, characterized in that, Based on the tilt angle of the ultrasonic transducer, the vertical distance from the surface of the ultrasonic transducer to the inner wall of the sleeve corresponding to that sector is calculated, including: The vertical distance from the surface of the ultrasonic transducer to the inner wall of the sleeve is calculated using the following formula: ； in, The vertical distance from the surface of the ultrasonic transducer to the inner wall of the sleeve is denoted as . This represents the propagation distance of the ultrasonic Lamb wave in the mud. The preset tilt angle for the ultrasonic transducer.

6. The method according to claim 1, characterized in that, Extracting the arrival time of the first reflected wave, which characterizes the arrival time of the first reflected wave of the ultrasonic Lamb wave, from the time-domain waveform signal includes: Based on the nominal inner diameter of the casing in the current well section, the outer diameter of the logging instrument, the mud velocity, and the preset tilt angle of the ultrasonic transducer, the theoretical arrival time range of the first reflection wave of the ultrasonic Lamb wave is calculated. Within the theoretical arrival time range, identify the peak point with the largest amplitude in the time-domain waveform signal, and record the time corresponding to the peak point as the arrival time of the first reflected wave. Taking the arrival time of the first reflected wave as the center, waveform segments of a preset number of periods before and after are extracted as the signal to be matched. These segments are then subjected to normalized cross-correlation with a pre-calibrated standard Lamb wave first reflected wave template to obtain a cross-correlation function curve. The maximum peak point of the cross-correlation function curve is determined, and the time corresponding to the maximum peak point is the arrival time of the first reflected wave.

7. A sleeve inner diameter measuring device based on ultrasonic Lamb wave, based on the sleeve inner diameter measuring method based on ultrasonic Lamb wave according to any one of claims 1-6, characterized in that, include: The first reflected wave arrival time extraction unit is used to emit obliquely incident ultrasonic Lamb waves to the inner wall of the casing of the corresponding sector through multiple ultrasonic transducer strips distributed circumferentially on the logging instrument during the uniform movement of the logging instrument along the wellbore axis, and simultaneously collect the time domain waveform signal of the ultrasonic Lamb wave returned from each sector, and extract the first reflected wave arrival time, which represents the arrival time of the first reflected wave of the ultrasonic Lamb wave, from the time domain waveform signal. The propagation velocity determination unit is used to obtain the propagation velocity of ultrasonic Lamb waves in the casing wall based on the mud velocity value in the current well section measured in real time by the mud transducer and the preset tilt angle of the ultrasonic transducer. The vertical distance determination unit is used to determine the one-way propagation distance of the ultrasonic Lamb wave in the mud by using the geometric relationship of the propagation path of the ultrasonic Lamb wave in the mud and the casing, as well as the arrival time of the first reflected wave and the propagation speed for each sector. Based on the preset tilt angle of the ultrasonic transducer, the vertical distance from the surface of the ultrasonic transducer to the inner wall of the casing corresponding to the sector is calculated. The average casing inner diameter value determination unit is used to calculate the casing inner diameter value in different orientations based on the vertical distance from the ultrasonic transducer surface to the inner wall of the casing corresponding to all sectors and the known outer diameter of the logging instrument, and obtain the average casing inner diameter value through each casing inner diameter value.

8. An electronic device, characterized in that, The electronic device includes: At least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores a computer program executable by the at least one processor, the computer program being executed by the at least one processor to enable the at least one processor to perform the cannula inner diameter measurement method based on ultrasonic Lamb wave as described in any one of claims 1-6.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions that cause a processor to execute the method for measuring the inner diameter of a sleeve based on ultrasonic Lamb waves as described in any one of claims 1-6.

10. A computer program product, characterized in that, The computer program product includes a computer program that, when executed by a processor, implements the method for measuring the inner diameter of a sleeve based on ultrasonic Lamb waves according to any one of claims 1-6.

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