A wellbore integrity array ultrasonic measurement method and apparatus

Abstract

The application provides a wellbore integrity array ultrasonic measurement method and device, and belongs to the logging technical field in oil exploration and development. The method comprises the following steps: calculating real-time parameters of a casing and acoustic impedance of a medium behind the casing; acquiring direct lamb wave amplitude and travel time of different source distances; calculating lamb wave attenuation rate of the medium behind the casing, and calculating the eccentricity of the casing according to the time interval difference between the direct lamb wave and the secondary reflection echo; combining the acoustic impedance of the medium behind the casing and the lamb wave attenuation rate to identify the phase state of the medium behind the casing. The device comprises a drill tool body and an ultrasonic transducer array integrated on the drill tool body; the ultrasonic transducer array comprises, from bottom to top, a self-generation and self-reception ultrasonic pulse echo transducer, an oblique emission transducer and a plurality of oblique reception transducers. The application can realize the integrated measurement and repair requirements of the workover operation, and can give real-time evaluation of casing damage and cementing quality behind the casing, thereby providing a basis for real-time decision-making of the workover operation and guaranteeing the timeliness and safety of the operation.

Description

Technical Field

[0001] This invention relates to the field of well logging technology in oil exploration and development, and particularly to a wellbore integrity array ultrasonic measurement method and device. Background Technology

[0002] Wellbore integrity testing is a measurement performed after casing is installed in oil and gas wells. It is mainly used to evaluate casing damage and the quality of post-casing cement bonding.

[0003] Existing wellbore integrity testing instruments include acoustic amplitude logging (CBL), acoustic variable density logging (VDL), sector cement bond logging (SBT), and ultrasonic pulse echo logging. With the increasing application of low-density cement, traditional acoustic amplitude / variable density / sector cement bond logging operations cannot effectively identify low-density cement and suffer from casing eccentricity detection distortion. Domestic and international energy service companies have successively launched various types of cable ultrasonic pulse echo logging instruments for wellbore integrity, such as Schlumberger's IBC, CNOOC's UCCS, and Sinopec Engineering Institute's CBUI. These instruments can be used for casing damage, post-casing low-density cement bond quality, and casing eccentricity evaluation. However, these cable ultrasonic pulse echo instruments cannot be used for drill string delivery logging and cannot meet the needs of integrated logging and repair operations.

[0004] Cased wells are part of the oil and gas development phase. Throughout the oil and gas production lifecycle, wellbore integrity needs to be regularly monitored to provide decision-making support for well workover operations. Existing wellbore integrity testing instruments all rely on wireline logging, which cannot meet the measurement needs of well workover operations. This is especially true in deep-sea and deep-ground oil and gas wells, where well workover operations have stringent safety and time-sensitive requirements. Currently, well workover operations still require separate wellbore integrity measurements using wireline logging, increasing workover time and construction safety risks. Therefore, it is necessary to transform existing methods based on the characteristics of well workover operations. This involves integrating a wellbore integrity array ultrasonic measurement method and device into the well workover drilling tool to achieve integrated measurement and workover while drilling operations, thereby significantly improving the timeliness and safety of well workover operations. Summary of the Invention

[0005] In view of this, the present invention aims to provide a method and apparatus for array ultrasonic measurement of wellbore integrity, which can solve the problems in the background art mentioned above.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: The present invention provides a wellbore integrity array ultrasonic measurement method, comprising the following steps: Step S1: Use a self-transmitting and self-receiving ultrasonic pulse echo transducer to emit ultrasonic waves and receive echoes. Calculate the real-time parameters of the casing and the acoustic impedance of the medium behind the casing by combining the travel time of the first echo with the sound velocity of the well fluid. Step S2: Use an oblique ultrasonic transducer to emit ultrasonic waves and an oblique receiving transducer to receive the signals to obtain the amplitude and travel time of the direct Lamb wave at different source distances. Step S3: Based on the data obtained in step S2, calculate the Lamb wave attenuation rate of the medium behind the sleeve, and calculate the eccentricity of the sleeve according to the time interval difference between the direct Lamb wave and the secondary reflected echo. Step S4: Combine the acoustic impedance and Lamb wave attenuation rate of the backing medium to identify the phase state of the backing medium.

[0007] Furthermore, the real-time parameters of the casing include the casing inner diameter, casing thickness, casing outer diameter, and casing inner wall damage.

[0008] Furthermore, the natural logarithm of the signal amplitudes collected by multiple oblique receiving transducers is taken respectively, and a coordinate system is established with the source distance and the logarithmic signal amplitude as the coordinate axes. A straight line equation is fitted, and the slope of the straight line is the Lamb wave attenuation rate of the back medium. Here, the horizontal axis of the coordinate system represents the source distance of the oblique receiving transducers, and the vertical axis represents the signal amplitude.

[0009] Furthermore, the media include air, water, low-density cement, and conventional cement.

[0010] Furthermore, when identifying the phase state of the medium after the coating, the Lamb wave attenuation rate is used to first increase and then decrease with the increase of the medium's acoustic impedance. Combined with the acoustic impedance measured by the self-echoing ultrasonic pulse transducer, a two-dimensional joint interpretation chart is constructed to distinguish between air, water, low-density cement and conventional cement.

[0011] Furthermore, the formula for calculating the eccentricity of the casing is as follows:

[0012] In the formula, ΔT_R4_Azi0, ΔT_R4_Azi90, ΔT_R4_Azi180, and ΔT_R4_Azi270 represent the time intervals between the direct Lamb wave and the secondary reflection echo of the Lamb wave at four directions (0°, 90°, 180°, and 270°) of one of the oblique receiving transducers, respectively, and min and max represent taking the minimum and maximum values ​​of the array elements, respectively.

[0013] Furthermore, the casing inner diameter is calculated using the echo first wave travel time and well fluid velocity obtained from the self-generating and self-receiving ultrasonic pulse echo transducer. The sleeve thickness and the acoustic impedance of the medium behind the sleeve are calculated based on the reflected echo time window signal and the resonant wave time window signal; The outer diameter of the casing and the damage to the inner wall of the casing are calculated by using the casing thickness and the inner diameter of the casing.

[0014] The present invention also provides a wellbore integrity array ultrasonic measurement device for implementing the above-mentioned wellbore integrity array ultrasonic measurement method, comprising: The drill string body, and the ultrasonic transducer array integrated on the drill string body; The ultrasonic transducer array, from bottom to top, includes: a self-transmitting and self-receiving ultrasonic pulse echo transducer, an oblique ultrasonic transducer, and multiple oblique receiving transducers. The self-transmitting and self-receiving ultrasonic pulse echo transducer is used to transmit and receive ultrasonic waves perpendicular to the inner wall of the casing to calculate the real-time parameters of the casing and the acoustic impedance of the medium behind the casing. An oblique ultrasonic transducer is used to emit ultrasonic Lamb waves, and an oblique receiving transducer is used to receive Lamb waves propagating along the casing to calculate the parameters of the medium behind the casing.

[0015] Furthermore, there are four oblique receiving transducers, which are arranged in a four-source-pitch array.

[0016] Furthermore, the ultrasonic signals emitted by the self-echoing ultrasonic pulse transducer are incident vertically on the inner wall of the sheath; the ultrasonic signals emitted by the oblique ultrasonic transducer are incident on the inner wall of the sheath at an oblique angle.

[0017] Compared with existing technologies, the wellbore integrity array ultrasonic measurement method and device described in this invention have the following advantages: (1) The wellbore integrity array ultrasonic measuring device of the present invention integrates the measuring instrument on the drill body, which has higher structural strength than the existing cable instrument. It can realize wellbore integrity measurement during well workover operations, obtain information on casing damage and post-casing cement bonding quality, and at the same time meet the needs of real-time decision-making during well workover operations, reduce one trip of cable wellbore integrity logging operation, and improve the safety and timeliness of well workover operations. (2) The wellbore integrity array ultrasonic measurement device of the present invention can be used for multi-point direct Lamb wave amplitude fitting linear equation through array multi-source offset transducer. The slope of the linear equation is the Lamb wave attenuation rate of the back medium. Compared with the existing dual offset transducer measurement, it has richer measurement information and ensures the accuracy of Lamb wave attenuation rate measurement. (3) The wellbore integrity array ultrasonic measurement method of the present invention performs two-dimensional interpretation by combining the acoustic impedance of the back medium and the Lamb wave attenuation rate, which can accurately identify the phase state of the back medium, especially suitable for the identification of low-density cement, and solves the problem of difficult identification by traditional methods. (4) The wellbore integrity array ultrasonic measurement method described in this invention can realize an integrated measurement and repair operation mode under the background of high timeliness and high safety requirements of deep earth and deep sea well repair operations, which greatly improves the timeliness and safety of the operation. Attached Figure Description

[0018] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic diagram of the wellbore integrity array ultrasonic measurement device described in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the resonant wave waveform acquired by the self-generating and self-receiving ultrasonic pulse echo transducer provided in Embodiment 2 of the present invention; Figure 3 This is a schematic diagram of the Lamb wave waveform collected by the oblique transmitting and receiving transducer provided in Embodiment 2 of the present invention; Figure 4 This is a schematic diagram of the ultrasonic measurement parameter processing flow provided in Embodiment 2 of the present invention; Figure 5 This is a schematic diagram illustrating the principle of acoustic impedance calculation after the sleeve provided in Embodiment 2 of the present invention; Figure 6 This is a schematic diagram illustrating the calculation principle of the Lamb wave attenuation rate after the sleeve provided in Embodiment 2 of the present invention; Figure 7 This is a schematic diagram of the combined response of acoustic impedance and Lamb wave attenuation rate of different media after the sleeve provided in Embodiment 2 of the present invention.

[0019] Explanation of reference numerals in the attached figures: 1. Drill tool body; 11. Self-transmitting and self-receiving ultrasonic pulse echo transducer; 12. Inclined ultrasonic transducer; 13. Inclined receiving transducer. Detailed Implementation

[0020] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0021] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0022] This invention provides a method for array ultrasonic measurement of wellbore integrity, comprising the following steps: Step S1: Use the self-emitting and self-receiving ultrasonic pulse echo transducer 11 to emit ultrasonic waves and receive echoes. Calculate the real-time parameters of the casing and the acoustic impedance of the medium behind the casing by combining the travel time of the first echo with the sound velocity of the well fluid. The real-time parameters of the casing include the casing inner diameter, casing thickness, casing outer diameter, and casing inner wall damage. The casing inner diameter is calculated using the echo first-wave travel time and well fluid velocity obtained by the self-echoing ultrasonic pulse echo transducer 11; the casing thickness and the acoustic impedance of the medium behind the casing are calculated based on the reflected echo time window signal and the resonant wave time window signal; the casing outer diameter and casing inner wall damage are calculated using the casing thickness and casing inner diameter.

[0023] The medium includes air, water, low-density cement, and conventional cement.

[0024] Step S2: Ultrasonic waves are emitted using the oblique ultrasonic transducer 12 and received by the oblique receiving transducer 13 to obtain the amplitude and travel time of the direct Lamb wave at different source distances. Step S3: Based on the data obtained in step S2, calculate the Lamb wave attenuation rate of the medium behind the sleeve, and calculate the eccentricity of the sleeve according to the time interval difference between the direct Lamb wave and the secondary reflected echo. The natural logarithm of the signal amplitudes collected by multiple oblique receiving transducers 13 is taken respectively. A coordinate system is established with the source distance and the logarithmic signal amplitude as the coordinate axes, and a straight line equation is fitted. The slope of the straight line is the Lamb wave attenuation rate of the back medium. The horizontal axis of the coordinate system represents the source distance of the oblique receiving transducers 13, and the vertical axis represents the signal amplitude.

[0025] The formula for calculating the eccentricity of the casing is:

[0026] In the formula, ΔT_R4_Azi0, ΔT_R4_Azi90, ΔT_R4_Azi180, and ΔT_R4_Azi270 represent the time intervals between the direct Lamb wave and the secondary reflection echo of the Lamb wave at four directions (0°, 90°, 180°, and 270°) of one of the oblique receiving transducers 13, and min and max represent taking the minimum and maximum values ​​of the array elements, respectively.

[0027] Step S4: Combine the acoustic impedance and Lamb wave attenuation rate of the backing medium to identify the phase state of the backing medium.

[0028] When identifying the phase state of the medium after the coating, the Lamb wave attenuation rate is used to first increase and then decrease with the increase of the acoustic impedance of the medium. Combined with the acoustic impedance measured by the self-generated and self-received ultrasonic pulse echo transducer 11, a two-dimensional joint interpretation chart is constructed to distinguish between air, water, low-density cement and conventional cement.

[0029] The present invention also provides a wellbore integrity array ultrasonic measurement device for implementing the above-mentioned wellbore integrity array ultrasonic measurement method, comprising: Drill body 1, and ultrasonic transducer array integrated on drill body 1; The ultrasonic transducer array, from bottom to top, includes: a self-transmitting and self-receiving ultrasonic pulse echo transducer 11, an oblique ultrasonic transducer 12, and multiple oblique receiving transducers 13. The self-emitting and self-receiving ultrasonic pulse echo transducer 11 is used to transmit and receive ultrasonic waves perpendicular to the inner wall of the sleeve to calculate the real-time parameters of the sleeve and the acoustic impedance of the medium behind the sleeve; the ultrasonic signal emitted by the self-emitting and self-receiving ultrasonic pulse echo transducer 11 is perpendicularly incident on the inner wall of the sleeve. An oblique-emitting ultrasonic transducer 12 is used to emit ultrasonic Lamb waves, and an oblique-receiving transducer 13 is used to receive the Lamb waves propagating along the sleeve to calculate the parameters of the medium behind the sleeve. The ultrasonic signal emitted by the oblique-emitting ultrasonic transducer 12 is incident on the inner wall of the sleeve at an oblique angle. In the description of this invention, it should be understood that the terms "upper," "lower," "inner," "outer," etc., indicating the orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0030] The wellbore integrity array ultrasonic measurement device can realize the integrated measurement and repair requirements of well workover operations, and provide real-time evaluation of casing damage and post-casing cement bonding quality, providing a reliable basis for real-time decision-making in well workover operations, and ensuring the timeliness and safety of the operation.

[0031] As an optional embodiment of the wellbore integrity array ultrasonic measurement device of the present invention, the number of oblique receiving transducers 13 is four, and the four oblique receiving transducers 13 are distributed in a four-source-pitch array. The echo waveforms received by the self-transmitting and self-receiving ultrasonic pulse echo transducers 11 can be processed to calculate the casing inner diameter, casing thickness, casing outer diameter, casing inner wall damage, and acoustic impedance of the medium behind the casing. The oblique transmitting ultrasonic transducers 12 emit ultrasonic Lamb waves, and the four echo waveforms received by the four oblique receiving transducers 13 can be used to calculate the Lamb wave attenuation rate of the medium behind the casing, and can reflect the casing eccentricity. By combining the acoustic impedance of the medium behind the casing and the Lamb wave attenuation rate, the phase state of the medium can be identified.

[0032] Example 1

[0033] like Figures 1 to 7 As shown, a method for array ultrasonic measurement of wellbore integrity includes: Step S1: Use the self-emitting and self-receiving ultrasonic pulse echo transducer 11 to emit ultrasonic waves and receive echoes. Calculate the real-time parameters of the casing and the acoustic impedance of the medium behind the casing by combining the travel time of the first echo with the sound velocity of the well fluid. Step S2: Ultrasonic waves are emitted using the oblique ultrasonic transducer 12 and received by the oblique receiving transducer 13 to obtain the amplitude and travel time of the direct Lamb wave at different source distances. Step S3: Based on the data obtained in step S2, calculate the Lamb wave attenuation rate of the medium behind the sleeve, and calculate the eccentricity of the sleeve according to the time interval difference between the direct Lamb wave and the secondary reflected echo. Step S4: Combine the acoustic impedance and Lamb wave attenuation rate of the backing medium to identify the phase state of the backing medium.

[0034] Specifically, the data acquired by the self-generating and self-receiving ultrasonic pulse echo transducer (T / R) 11 is processed and calculated: First, the travel time of the first echo wave is extracted, and the casing inner diameter is calculated by combining the known sound velocity of the wellbore fluid. The amplitude of the first echo wave is then extracted to reflect the physical state of the inner wall of the casing. Then, based on the signals within the reflected echo time window and the resonant wave time window, the sleeve thickness and the acoustic impedance of the medium behind the sleeve are calculated. Finally, the outer diameter of the casing is calculated from the casing thickness and the inner diameter of the casing.

[0035] For data collected by the oblique transmitting and receiving transducer: First, the amplitude and travel time of the direct Lamb wave at different source distances, as well as the travel time of the Lamb wave secondary reflection echo, are extracted. Based on the amplitude of the direct Lamb wave at different source distances, the Lamb wave attenuation rate of the backing medium is calculated.

[0036] Then, based on the time interval between the direct Lamb wave and the second reflected Lamb wave echo, the sleeve eccentricity Pecc is calculated. Taking the farthest oblique receiving transducer R4 as an example, its four time intervals are represented as ΔT_R4_Azi0, ΔT_R4_Azi90, ΔT_R4_Azi180, and ΔT_R4_Azi270, respectively. The formula for calculating the eccentricity Pecc is: (1) The Pecc value is between 0 and 1, where 0 indicates that the casing is centered and 1 indicates that the casing is completely off-center.

[0037] like Figure 2 and Figure 3 As shown, the pulse echo waveform signal received by the self-generated and self-received ultrasonic pulse echo transducer (T / R) 11 and the Lamb wave waveform received by the oblique receiving transducers R1 to R4 are respectively displayed when the medium inside and outside the casing is clean water. According to the ultrasonic measurement principle, the pulse echo waveform signal receives the first reflected echo signal and the subsequent resonant wave signal in sequence. The four oblique receiving transducers receive the direct Lamb wave signals TT1_R1, TT1_R2, TT1_R3, and TT1_R4 and the second reflected Lamb wave signals TT2_R1, TT2_R2, TT2_R3, and TT2_R4 in sequence. The waveform signal response shows that the instrument design conforms to the ultrasonic measurement principle.

[0038] like Figure 4As shown, based on the raw data collected at different depths, measurement parameters are processed. The self-emitting and self-receiving ultrasonic pulse echo transducer 11 can obtain the echo first wave travel time TT. Combined with the well fluid sound velocity Vf, the casing inner diameter RADI can be calculated. The echo first wave amplitude Amp can reflect the physical state of the casing inner wall. Based on the reflected echo time window signal Tre and the resonance wave time window signal Trw, the casing thickness Ct and the impedance behind the casing Zc can be calculated. The casing outer diameter RADO can be calculated from the casing thickness Ct and the casing inner diameter RADI. The oblique-emitting and oblique-receiving transducer can obtain the amplitude and travel time of the direct Lamb wave at different source distances, as well as the travel time of the Lamb wave second reflection echo. The Lamb wave attenuation rate Att of the medium behind the casing can be calculated from the direct Lamb wave amplitude at different source distances. The time interval between the direct Lamb wave and the Lamb wave second reflection echo can reflect the... Figure 1 The cement thickness between the casing and the formation is the same in all directions when the casing is centered, and the time interval is also equal. When the casing is eccentric, the cement thickness in all directions is different, and the time interval is also unequal. Therefore, the degree of casing eccentricity Pecc can be calculated based on the time interval.

[0039] like Figure 5 As shown in the figure, the echo signals received by the self-echoing ultrasonic pulse echo transducer 11 under different backing media (air, water, low-density cement, and conventional cement) are represented. The acoustic impedance relationship is air < ​​water < low-density cement < conventional cement. As can be seen from the figure, the echo can be divided into a first-reflection echo time window Tre and a resonance wave time window Trw. The maximum waveform amplitude within the first-reflection echo time window is defined as R1, and the root mean square amplitude of the signal within the resonance wave time window is defined as R2. Then, the formula for calculating the acoustic impedance Zc of the backing medium is: (2) In the formula: Zc represents acoustic impedance, k1 and b1 represent scale coefficients, R1 represents the maximum amplitude in the reflected wave time window, and R2 represents the root mean square amplitude of the resonant wave time window signal.

[0040] The calibration coefficients k1 and b1 can be calculated by calibrating at least two media with known acoustic impedance. Multi-point calibration is usually used, i.e., air, water, low-density cement and conventional cement with known acoustic impedance. As the acoustic impedance of the medium increases, the amplitude of the resonant wave decreases accordingly.

[0041] like Figure 6As shown in the figure, given four different backing media (air, water, low-density cement, and conventional cement), the amplitudes of direct Lamb wave signals received by oblique receiving transducers with different source distances were obtained. Taking the logarithm of the signal amplitude, it can be seen from the figure that the signal amplitude changes linearly with the increase of the source distance, and the slope is in the order of air < ​​water < low-density cement < conventional cement. Since the horizontal axis represents the source distance of oblique receiving transducer 13 and the vertical axis represents the signal amplitude, the slope represents the change in signal amplitude per unit distance. That is, by performing least squares fitting on the signal amplitudes of the four oblique receiving transducers 13, the linear equation of the relationship between source distance and signal amplitude can be obtained as follows: (3) In the formula, y represents the signal amplitude of the oblique receiving transducer 13, x represents the source distance of the oblique receiving transducer 13, and k2 and b2 represent the coefficients of the linear equation obtained by least squares fitting.

[0042] Therefore, the Lamb wave attenuation rate Att can be expressed as:

[0043] In the formula, Att represents the Lamb wave attenuation rate, and k2 represents the slope in the linear equation of formula (3).

[0044] like Figure 7 As shown in the figure, given four different backfill media (air, water, low-density cement, and conventional cement), the Lamb wave attenuation rate corresponding to different acoustic impedance media is calculated from the collected raw ultrasonic Lamb wave data. The figure shows that the Lamb wave attenuation rate first increases and then decreases with the increase of the medium's acoustic impedance. Therefore, a two-dimensional joint interpretation method is formed by combining ultrasonic pulse echo measurement and array ultrasonic Lamb wave measurement. Since the acoustic impedance of low-density cement is close to that of water, this two-dimensional interpretation method is also applicable to the case where the backfill medium is low-density cement. By jointly interpreting the backfill medium's acoustic impedance and Lamb wave attenuation rate, the gas-liquid-solid phase state of the backfill medium can be accurately identified. This ultrasonic measurement method and device for wellbore integrity enables an integrated measurement and repair operation, completing the evaluation and measurement of cementing quality during the well repair process, providing real-time guidance and optimization of the well repair construction plan, and improving the timeliness and safety of well repair operations.

[0045] Therefore, a two-dimensional joint interpretation chart is formed by combining the acoustic impedance of the back-coated medium obtained by ultrasonic pulse echo measurement and the Lamb wave attenuation rate obtained by array ultrasonic Lamb wave measurement. This two-dimensional interpretation method can effectively distinguish between gas, liquid, and solid phases, and is especially suitable for the identification of low-density cement with acoustic impedance close to that of water, solving the problem of identification difficulties with traditional single measurement methods.

[0046] In summary, the wellbore integrity array ultrasonic measurement method and device provided by this invention integrates the ultrasonic transducer into the drill string body 1, realizing integrated measurement and repair operations. During well workover operations, key parameters such as casing inner diameter, thickness, damage, acoustic impedance of the medium behind the casing, Lamb wave attenuation rate, and casing eccentricity can be acquired in real time. Furthermore, by combining acoustic impedance and Lamb wave attenuation rate, the phase state of the medium behind the casing can be accurately identified, providing real-time decision-making basis for well workover operations and significantly improving the timeliness and safety of the operation.

[0047] Example 2

[0048] like Figure 1 As shown, a wellbore integrity array ultrasonic measurement device is used to implement the method described in Embodiment 1. The measurement device includes: a drill string body 1, and an ultrasonic transducer array integrated on the drill string body 1; the ultrasonic transducer array includes, from bottom to top: a self-emitting and self-receiving ultrasonic pulse echo transducer 11, an oblique-emitting ultrasonic transducer 12, and four oblique-receiving transducers 13; wherein, the self-emitting and self-receiving ultrasonic pulse echo transducer (T / R) 11 emits an ultrasonic signal with a center frequency of f1, which is perpendicularly incident on the inner wall of the casing through the wellbore fluid. Most of the energy is reflected back to the transducer through the inner wall of the casing, forming a primary reflected echo; a small portion of the energy enters the casing and is reflected multiple times between the inner walls of the casing, forming a casing resonance wave, which appears after the primary reflected echo; and a very small portion of the energy passes through the casing and enters the downstream medium, which is usually negligible. The oblique-emitting ultrasonic transducer 12T emits an ultrasonic signal with a center frequency of f2 and is incident on the inner wall of the casing at a certain angle θ, exciting a Lamb wave in the casing. As the Lamb wave propagates along the sleeve, energy continuously leaks to both sides. Part of this energy propagates directly to the oblique receiving transducers R1 to R4, forming a direct Lamb wave; the other part is reflected by the medium behind the sleeve at an angle θ1 and re-enters the sleeve, propagating to the oblique receiving transducers 13, forming a secondary reflection echo of the Lamb wave. The echo waveforms received by the self-transmitting and self-receiving ultrasonic pulse echo transducer (T / R) 11, after data processing, can be used to calculate the sleeve's inner diameter, thickness, outer diameter, inner wall damage, and acoustic impedance of the medium behind the sleeve. The oblique ultrasonic transducer 12 emits ultrasonic Lamb waves, and the four echo waveforms received by the four oblique receiving transducers 13 can be used to calculate the Lamb wave attenuation rate of the medium behind the sleeve, reflecting the sleeve's eccentricity. Combining the acoustic impedance of the medium behind the sleeve and the Lamb wave attenuation rate allows for the identification of the medium's phase state.

[0049] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for array ultrasonic measurement of wellbore integrity, characterized in that, Includes the following steps: Step S1: Use a self-transmitting and self-receiving ultrasonic pulse echo transducer to emit ultrasonic waves and receive echoes. Calculate the real-time parameters of the casing and the acoustic impedance of the medium behind the casing by combining the travel time of the first echo with the sound velocity of the well fluid. Step S2: Use an oblique ultrasonic transducer to emit ultrasonic waves and an oblique receiving transducer to receive the signals to obtain the amplitude and travel time of the direct Lamb wave at different source distances. Step S3: Based on the data obtained in step S2, calculate the Lamb wave attenuation rate of the medium behind the sleeve, and calculate the eccentricity of the sleeve according to the time interval difference between the direct Lamb wave and the secondary reflected echo. Step S4: Combine the acoustic impedance and Lamb wave attenuation rate of the backing medium to identify the phase state of the backing medium.

2. The wellbore integrity array ultrasonic measurement method according to claim 1, characterized in that: Real-time parameters of the casing include the inner diameter of the casing, the thickness of the casing, the outer diameter of the casing, and the damage to the inner wall of the casing.

3. The wellbore integrity array ultrasonic measurement method according to claim 1, characterized in that: The natural logarithm of the signal amplitudes collected by multiple oblique receiving transducers is taken respectively. A coordinate system is established with the source distance and the logarithmic signal amplitude as the coordinate axes, and a straight line equation is fitted. The slope of the straight line is the Lamb wave attenuation rate of the back medium. The horizontal axis of the coordinate system represents the source distance of the oblique receiving transducers, and the vertical axis represents the signal amplitude.

4. The wellbore integrity array ultrasonic measurement method according to claim 1, characterized in that: The medium includes air, water, low-density cement, and conventional cement.

5. The wellbore integrity array ultrasonic measurement method according to claim 1, characterized in that: When identifying the phase state of the medium after the coating, the Lamb wave attenuation rate is used to determine the law that it first increases and then decreases with the increase of the acoustic impedance of the medium. Combined with the acoustic impedance measured by the self-echoing ultrasonic pulse transducer, a two-dimensional joint interpretation chart is constructed to distinguish between air, water, low-density cement and conventional cement.

6. The wellbore integrity array ultrasonic measurement method according to claim 1, characterized in that: The formula for calculating the eccentricity of the casing is: In the formula, ΔT_R4_Azi0, ΔT_R4_Azi90, ΔT_R4_Azi180, and ΔT_R4_Azi270 represent the time intervals between the direct Lamb wave and the secondary reflection echo of the Lamb wave at four directions (0°, 90°, 180°, and 270°) of one of the oblique receiving transducers, respectively, and min and max represent taking the minimum and maximum values ​​of the array elements, respectively.

7. The wellbore integrity array ultrasonic measurement method according to claim 1, characterized in that: The casing inner diameter is calculated using the echo first wave travel time and well fluid velocity obtained from a self-generating and self-receiving ultrasonic pulse echo transducer. The sleeve thickness and the acoustic impedance of the medium behind the sleeve are calculated based on the reflected echo time window signal and the resonant wave time window signal; The outer diameter of the casing and the damage to the inner wall of the casing are calculated by using the casing thickness and the inner diameter of the casing.

8. A wellbore integrity array ultrasonic measurement device, used to implement the wellbore integrity array ultrasonic measurement method according to any one of claims 1-7, characterized in that, include: The drill string body, and the ultrasonic transducer array integrated on the drill string body; The ultrasonic transducer array, from bottom to top, includes: a self-transmitting and self-receiving ultrasonic pulse echo transducer, an oblique ultrasonic transducer, and multiple oblique receiving transducers. The self-transmitting and self-receiving ultrasonic pulse echo transducer is used to transmit and receive ultrasonic waves perpendicular to the inner wall of the casing to calculate the real-time parameters of the casing and the acoustic impedance of the medium behind the casing. An oblique ultrasonic transducer is used to emit ultrasonic Lamb waves, and an oblique receiving transducer is used to receive Lamb waves propagating along the casing to calculate the parameters of the medium behind the casing.

9. The wellbore integrity array ultrasonic measurement device according to claim 8, characterized in that: There are four oblique receiving transducers, which are arranged in a four-source-pitch array.

10. The wellbore integrity array ultrasonic measurement device according to claim 8, characterized in that: The ultrasonic signals emitted by the self-echoing ultrasonic pulse transducer are incident perpendicularly on the inner wall of the sheath; the ultrasonic signals emitted by the oblique ultrasonic transducer are incident at an oblique angle on the inner wall of the sheath.

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