Method, device, equipment and medium for cased hole quality inversion using dipole acoustic logging

Abstract

The present invention provides a method, device, equipment and medium for inversion of casing well quality by dipole acoustic logging, which belongs to the field of acoustic logging. The method extracts the dispersion curve of the high-order casing bending mode wave from the array acoustic logging data, and then compares the similarity between the dispersion curve and the theoretical dispersion curve. The obtained similarity coefficient is normalized according to the well section to obtain the bonding index, thereby inverting the bonding condition of the outer annulus of the casing well. The device for executing the method includes: an array acoustic logging instrument and a ground control system; the ground control system includes a signal generator and a receiver, an electronic circuit, and a host computer; the signal generator and the receiver are connected to the array acoustic logging instrument through an electronic circuit. The present invention has a stable effect and high accuracy, and can penetrate the fluid space of multiple layers of tubing and its outer layer to quickly and accurately obtain the bonding condition of the outer annulus.

Description

Technical Field

[0001] The invention belongs to the field of acoustic well logging, and in particular relates to a method, device, equipment and medium for cased well quality inversion in dipole acoustic logging. Background Art

[0002] The detection of cementing quality in cased wells based on acoustic logging is a topic of great concern in the field of oil and gas exploration and development. In order to prevent uncontrolled leakage of underground fluids to the formation or surface, the integrity of the wellbore needs to be evaluated before the well abandonment operation to ensure that the cement sheath outside the casing is well bonded and to achieve long-term plugging of the oil and gas well. The traditional operation of judging the cementing quality of production wells requires removing the production tubing before logging, which greatly increases the operation cost. The current mainstream research is common in the logging and cementing quality of traditional double-layer cased wells. For example, Chinese patent CN118818619A (publication date: October 22, 2024) discloses a cementing quality evaluation method and device based on orthogonal dipole acoustic logging. The method includes: according to the first waveform data and the second waveform data of the monopole transmitting transducer, the target cementing quality evaluation data is obtained by simulation calculation, and the target cementing quality evaluation data equivalent to the cementing quality evaluation index obtained based on the target logging instrument can be obtained based on the orthogonal dipole acoustic logging data. This method is only applicable to the single-layer tubing logging cementing quality method.

[0003] Although Chinese patent CN116411937A (publication date: July 11, 2023) discloses a logging tool, casing and method for measuring the quality of production casing cementing through the tubing, the core of the invention is based on an electromagnetic ultrasonic logging tool, which directly excites and receives ultrasonic signals in the tubing, avoiding the huge interface loss of the signal from gas to solid. The present invention can solve the technical problem that the excited ultrasonic wave cannot effectively pass through the gas-solid interface, and thus cannot achieve the technical problem of measuring the quality of casing cementing through the tubing. However, the invention cannot ensure the accuracy of the logging results, lacks accuracy, and cannot avoid the influence of the fluid annulus outside the tubing on the quality results. Therefore, the method of acoustic logging cementing quality through the tubing is in urgent need of development. Summary of the Invention

[0004] To solve the above problems, the present invention provides a dipole acoustic logging casing well quality inversion method, device, equipment and medium, which uses the casing bending mode waves excited by the dipole sound source in the steel pipe to judge the cementation condition of the outer annulus.

[0005] A dipole acoustic logging cased well quality inversion method comprises the following steps:

[0006] S1. Perform dipole acoustic logging in a cased well to obtain array waveform data at a certain depth point;

[0007] S2. Process the dipole array waveform using the frequency-slowness correlation method to obtain the dispersion data of the high-order casing bending mode wave;

[0008] S3. Calculate the theoretical dispersion curves of high-order casing bending mode waves in multi-layer tubing strings;

[0009] S4, performing similarity analysis on the dispersion data of the high-order casing bending mode wave in step S2 and the theoretical dispersion curve calculated in step S3;

[0010] S5, repeating steps S1 to S4 to obtain the similarity coefficient of the entire depth range;

[0011] S6. Normalize the similarity coefficient obtained in step S5 to obtain the cementation index of the entire well section.

[0012] Furthermore, in step S2, the spectrum correlation method is used to calculate the dispersion data of the measured array waveform, and the correlation coefficient calculation formula of the dispersion data is:

[0013]

[0014] Where N is the number of array receivers; the intermediate quantity z = exp(-iωsd); ω is the acoustic angular frequency, i is the imaginary unit; s is the inverted slowness value; d is the receiver spacing; X n (ω) represents the frequency spectrum of a certain sound wave phase; * represents the complex conjugate of the function.

[0015] Furthermore, step S3 includes:

[0016] S31. Establish a characteristic matrix using the boundary conditions of each layer of media in a multi-layer tubing well:

[0017]

[0018] Among them, T is the acoustic angular frequency matrix of the cylindrical layer in the cased well, its superscript represents the serial number of the cylindrical layer in the well, and its subscript represents the cylindrical layer in the cased well: Mud is the mud layer, Solid is the inner and outer casing solid layer, Fluid is the fluid layer in the inner and outer annuli, and Formation is the formation matrix. The expression of each layer matrix includes the wave equation and boundary conditions of the elastic medium in the cylindrical coordinate system of the cylindrical layer in the cased well; O represents the zero matrix, and its subscript represents the matrix size; the vector X is the amplitude coefficient of each cylindrical layer in the cased well, its superscript represents the serial number of the cylindrical layer in the well, and its subscript represents each cylindrical layer in the cased well; the radial displacement on the right side of the equation is and radial stress It represents the direct wave radiated from the sound source to the well wall;

[0019] S32. Calculate the theoretical dispersion curve of the cased well dipole high-order casing bending mode wave using the dispersion equation:

[0020] det(M(ω, k))=0 (3) Where M represents the characteristic matrix in equation (2), ω is the angular frequency, and k is the wave number.

[0021] Furthermore, the similarity analysis in step S4 is specifically as follows: using the dispersion data of the high-order casing bending mode wave in step S2 and the theoretical dispersion curve calculated in step S3 to obtain the statistical value of the similarity coefficient at a certain depth point, the similarity degree formula for calculating the statistical value of the similarity coefficient can be expressed as:

[0022]

[0023] Where n represents the number of similar points; if represents whether the judgment condition is met, ρ represents the correlation coefficient of the dispersion data obtained in step S2; f represents frequency, F is the frequency range of processing, s represents slowness, S is the slowness range of processing, ρ t represents the extraction threshold of the correlation coefficient; ρ max Indicates that the maximum value of the correlation coefficient extraction threshold is obtained at a certain frequency; s t Indicates the range threshold of the absolute error of the slowness value; s Δ represents the absolute error between the processed slowness value and the theoretical slowness value, where the theoretical slowness value is obtained from the theoretical dispersion curve calculated in step S3.

[0024] Furthermore, the determination of whether the condition is met in the similarity point number statistics in step S4 includes the following steps:

[0025] S41. When counting the number of similar points n, determine the extraction threshold ρ of the correlation coefficient of the dispersion data t , when the correlation coefficient at a certain frequency is greater than the threshold and is the maximum value ρ at that frequency max When , the dispersion point corresponding to the correlation coefficient of the dispersion data can be recorded;

[0026] S42. Determine the range threshold s of the absolute error of the slowness value t , when the absolute error S between the slowness value of the dispersion point recorded in step S41 and the theoretical slowness value Δ When it is less than the threshold, the frequency dispersion point can be regarded as a statistical point;

[0027] S43. Record all statistical points within the frequency range to determine the number n of similar points.

[0028] Furthermore, step S5 includes: after obtaining the statistical value of the similarity coefficient of a certain depth point in step S4, continuing to repeat steps S1 to S4 for the remaining depth points of the cased well to obtain the statistical value of the similarity coefficient of the entire depth range.

[0029] Furthermore, in step S6, normalization processing is performed based on the statistical value n of the similarity coefficient of all recording points in the well section. The normalized value is the cementation index index for judging the quality of dipole cementing. The cementation index is calculated as follows:

[0030]

[0031] where n min is the minimum number of similar points; n max is the maximum number of similar points.

[0032] In a second aspect, the present invention provides a dipole acoustic logging cased hole quality inversion device for performing the method, the device comprising: an array acoustic logging instrument and a surface control system;

[0033] The ground control system includes a signal generator and receiver, electronic circuits, and a host computer;

[0034] The host computer is equipped with a software operating system, which includes an array waveform data acquisition module, a dispersion data processing module, a theoretical dispersion curve processing module, a similarity coefficient acquisition module, and a normalization processing module;

[0035] The array waveform data acquisition module controls the signal generator, receiver and array acoustic logging instrument to obtain array waveform data at a certain depth point;

[0036] The dispersion data processing module is used to execute step S2;

[0037] The theoretical dispersion curve processing module is used to execute step S3;

[0038] The similarity coefficient acquisition module is used to execute steps S4 and S5;

[0039] The normalization processing module is used to execute step S6;

[0040] The signal generator and receiver are connected to the array acoustic logging instrument through the electronic circuit and are connected to the host computer signal, and are used to control the array acoustic logging instrument to generate and receive signals, and to perform mutual conversion between digital signals and analog signals;

[0041] The electronic circuit is used to transmit signals;

[0042] The array acoustic logging instrument comprises a plurality of array receiving transducers, a sound insulation device, and a transmitting transducer, and is used to obtain array waveform data at different depth points in the cased well;

[0043] A plurality of array receiving transducers are arranged on the upper portion of the array acoustic logging instrument, and are used to receive dipole signals downhole;

[0044] The sound insulation device is provided below the plurality of array receiving transducers and is used to isolate the direct wave signal propagating along the array acoustic logging instrument;

[0045] The transmitting transducer is arranged below the sound insulation device and is used to excite a dipole signal underground.

[0046] In a third aspect, the present invention provides an electronic device, comprising:

[0047] processor;

[0048] Memory;

[0049] and a computer program, wherein the computer program is stored in the memory, the computer program comprising instructions that, when executed by the processor, cause the electronic device to perform the dipole acoustic logging cased hole quality inversion method.

[0050] In a fourth aspect, the present invention provides a computer-readable storage medium, which includes a stored program, wherein when the program is running, the device where the computer-readable storage medium is located is controlled to execute the dipole acoustic logging casing well quality inversion method.

[0051] Compared with the existing technology, the advantages and effects of this application are as follows:

[0052] 1. The present invention provides a dipole acoustic logging cased well quality inversion device, which is based on an array acoustic logging instrument. Through dipole acoustic logging, cementing quality detection can be performed without removing the production tubing, with high accuracy and saving production costs.

[0053] 2. The present invention provides a dipole acoustic logging cased well quality inversion method, which utilizes the characteristics of the casing bending mode waves corresponding to the tubing and casing having different frequency ranges, effectively avoiding the influence of the fluid annulus outside the tubing on the quality results, and has good anti-interference performance.

[0054] 3. The present invention provides a dipole acoustic logging cased well quality inversion method. The calculated high-order casing bending mode wave is only sensitive to the cementation condition of the annulus outside the casing and is less sensitive to formation changes. The quality results have high stability.

[0055] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application so that it can be implemented in accordance with the contents of the specification, and to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the following is a detailed description of the preferred embodiment of the present application in conjunction with the accompanying drawings.

[0056] Based on the detailed description of the specific embodiments of the present application in conjunction with the accompanying drawings below, those skilled in the art will become more aware of the above and other objects, advantages and features of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings required for the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present application. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings without inventive work. In all drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn according to the actual scale.

[0058] in:

[0059] Figure 1 This is a flow chart of a method for cased hole quality inversion using dipole acoustic logging according to an embodiment of the present invention;

[0060] Figure 2 A schematic diagram of a cased hole quality inversion device for dipole acoustic logging according to an embodiment of the present invention;

[0061] Figure 3 This is a schematic diagram of a dipole acoustic logging cased well quality inversion device - tubing - casing model according to an embodiment of the present invention, wherein Figure 3 (a) is a schematic diagram of a tubing-casing model well. Figure 3 (b) and Figure 3 (c) is a schematic diagram of two cross sections;

[0062] Figure 4 Array waveforms and extracted dispersion curves measured in a practical environment according to an embodiment of the present invention; Figure 4 (a) shows the measured waveform when the bonding is good and Figure 4 (b) shows the measured waveform when the free casing is used with this device. Figure 4 (c) Display Figure 4 (a) Frequency-slowness coherence diagram and dispersion curve of the measured waveform and Figure 4 (d) Display Figure 4 (b) Frequency-slowness coherence diagram and dispersion curve of the measured waveform;

[0063] Figure 5 Schematic diagram of calculation of similarity of high-order casing bending mode waves in a practical environment according to an embodiment of the present invention; Figure 5 (a) is the frequency range of high-order casing bending mode waves, Figure 5 (b) includes the absolute error S Δ Frequency range of high-order casing bending mode waves of the line segment;

[0064] Figure 6 A logging curve obtained by processing array waveforms based on a dipole acoustic logging cased hole quality inversion method according to an embodiment of the present invention;

[0065] Figure numerals: 1. signal generator and receiver; 2. electronic circuit; 3. host computer; 4. array receiving transducer; 5. sound insulation device; 6. transmitting transducer; 7. production tubing; 8. inner annulus; 9. outer annulus; 10. derrick. DETAILED DESCRIPTION

[0066] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all of the embodiments. In the following description, specific details such as specific configurations and components are provided only to help fully understand the embodiments of the present application. Therefore, it should be clear to those skilled in the art that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present application. In addition, for clarity and brevity, the description of known functions and structures has been omitted in the embodiments.

[0067] It should be understood that references throughout this specification to "one embodiment" or "this embodiment" mean that a particular feature, structure, or characteristic associated with the embodiment is included in at least one embodiment of the present application. Therefore, the appearance of "one embodiment" or "this embodiment" throughout this specification does not necessarily refer to the same embodiment. Furthermore, these particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0068] In addition, the present application may repeat reference numerals and / or letters in different examples. This repetition is for the purpose of simplicity and clarity and does not in itself indicate the relationship between the various embodiments and / or settings discussed.

[0069] The term "and / or" in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, B exists alone, and A and B exist at the same time. The term " / and" in this article describes another type of association object relationship, indicating that there can be two relationships. For example, A / and B can mean: A exists alone, and A and B exist alone. In addition, the character " / " in this article generally indicates that the related objects before and after are in an "or" relationship.

[0070] The term "at least one" in this article is merely a description of the association relationship between associated objects, indicating that three relationships may exist. For example, at least one of A and B can mean: A exists alone, A and B exist at the same time, and B exists alone.

[0071] It should also be noted that, in this document, relational terms such as first and second are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include," "comprises," or any other variations thereof are intended to cover non-exclusive inclusion.

[0072] Example 1

[0073] like Figure 1 As shown, this embodiment, based on embodiment 1, relates to a method for cased well quality inversion of dipole acoustic logging, comprising the following steps:

[0074] S1. Perform dipole acoustic logging in a cased well to obtain array waveform data at a certain depth point;

[0075] S2. Process the dipole array waveform using the frequency-slowness correlation method to obtain the dispersion data of the high-order casing bending mode wave;

[0076] The spectral correlation method is used to calculate the dispersion data of the measured array waveform. The correlation coefficient of the dispersion data is expressed as:

[0077]

[0078] Where N is the number of array receivers; the intermediate quantity z = exp(-iωsd); ω is the acoustic angular frequency, i is the imaginary unit; s is the inverted slowness value; d is the receiver spacing; X n (ω) represents the frequency spectrum of a certain sound wave phase; * represents the complex conjugate of the function.

[0079] S3. Calculate the theoretical dispersion curves of high-order casing bending mode waves in multi-layer tubing strings;

[0080] The characteristic matrix is ​​established using the boundary conditions of each layer of media in a multi-layer tubing well:

[0081]

[0082] Where T is the acoustic angular frequency matrix of the cylindrical layer in the cased well, its superscript represents the serial number of the cylindrical layer in the well, and its subscript represents the cylindrical layer in the cased well: Mud is the mud layer, Solid is the inner and outer casing solid layer, Fluid is the fluid layer in the inner and outer annuli, and Formation is the formation matrix. The expression of each layer matrix includes the wave equation and boundary conditions of the elastic medium in the cylindrical coordinate system of the cylindrical layer in the cased well; O represents the zero matrix, and its subscript represents the matrix size, for example, O 4×6 for Vector X is the amplitude coefficient of each cylindrical layer in the cased well. Its superscript represents the serial number of the cylindrical layer in the well, and its subscript represents each cylindrical layer in the cased well. The radial displacement on the right side of the equation is and radial stress It represents the direct wave radiated from the sound source to the well wall;

[0083] The dispersion curve of the dipole high-order casing bending mode wave in cased wells is calculated using the dispersion equation:

[0084] det(M(ω, k))=0 (3)

[0085] Where M represents the characteristic matrix in equation (2), ω is the angular frequency, and k is the wave number.

[0086] S4. Utilize the dispersion data of the high-order casing bending mode wave in step S2 and the theoretical dispersion curve calculated in step S3 to obtain the statistical value of the similarity coefficient at a certain depth point. The similarity degree formula for calculating the statistical value of the similarity coefficient can be expressed as:

[0087]

[0088] Where n represents the number of similar points; if represents whether the judgment condition is met, ρ represents the correlation coefficient of the dispersion data obtained in step S2; f represents frequency, F is the frequency range of processing, s represents slowness, S is the slowness range of processing, ρ t represents the extraction threshold of the correlation coefficient; ρ max Indicates that the maximum value of the correlation coefficient extraction threshold is obtained at a certain frequency; s t Indicates the range threshold of the absolute error of the slowness value; s Δ represents the absolute error between the processed slowness value and the theoretical slowness value, where the theoretical slowness value is obtained from the theoretical dispersion curve calculated in step S3.

[0089] The following steps are involved in determining whether the conditions are met during the similarity point counting process:

[0090] In the step S4, determining whether the condition is met in the similarity point number statistics includes the following steps:

[0091] S41. When counting the number of similar points n, determine the extraction threshold ρ of the correlation coefficient of the dispersion datat , when the correlation coefficient at a certain frequency is greater than the threshold and is the maximum value ρ at that frequency max When , the dispersion point corresponding to the correlation coefficient of the dispersion data can be recorded;

[0092] S42. Determine the range threshold s of the absolute error of the slowness value t , when the absolute error s between the slowness value of the dispersion point recorded in step S41 and the theoretical slowness value Δ When it is less than the threshold, the frequency dispersion point can be regarded as a statistical point;

[0093] S43. Record all statistical points within the frequency range to determine the number n of similar points.

[0094] After obtaining the statistical value of the similarity coefficient at a certain depth point in step S5 and step S4, continue to repeat steps S1 to S4 for the remaining depth points in the cased well to obtain the statistical value of the similarity coefficient for the entire depth range;

[0095] S6. Normalize the statistical value of the similarity coefficient obtained in S5 to obtain the cementation index of the entire well section.

[0096] Normalization is performed based on the number n of similar points of all recorded points in the well section. The normalized value is the cementation index index for dipole cementing quality evaluation. The cementation index is calculated as follows:

[0097]

[0098] where n min is the minimum number of similar points; n max is the maximum number of similar points.

[0099] Furthermore, the dipole signal reflected by various media in the well includes a first-order casing bending mode wave, a formation bending mode wave and a high-order casing bending mode wave. The first-order casing bending mode wave includes the acoustic angular frequency and amplitude coefficient of the mud layer in the oil pipe, the inner casing solid layer, and the inner fluid layer; the formation bending mode wave includes the acoustic angular frequency and amplitude coefficient of the formation; and the high-order casing bending mode wave includes the acoustic angular frequency and amplitude coefficient of the outer casing solid layer and the outer fluid layer.

[0100] The method described in this embodiment can be implemented using electronic devices and computer-readable storage media in the prior art, and will not be described in detail.

[0101] Technical effect of this embodiment: This embodiment provides a dipole acoustic logging and cementing quality method for a multi-layer tubing, which extracts the dispersion curve of the high-order casing bending mode wave from the array acoustic logging data, and then compares the similarity between the high-order casing bending mode wave and the extracted high-order casing bending mode wave. The obtained similarity coefficient is normalized according to the well section to obtain the cementation index, thereby inverting the cementation condition of the outer annulus of the casing well. The effect is stable and the accuracy is high. It can penetrate the multi-layer tubing and the fluid space of its outer layer to quickly and accurately judge the cementation condition of the outer annulus.

[0102] Example 2

[0103] like Figure 2 As shown, this embodiment provides a dipole acoustic logging cased well quality inversion device for executing the method described in Example 1. The device is a multi-layer cased well quality data inversion device based on dipole acoustic waves, characterized in that the device includes: an array acoustic logging instrument and a ground control system;

[0104] The ground control system includes a signal generator and receiver 1, an electronic circuit 2, and a host computer 3;

[0105] The host computer 3 is equipped with a software operating system, which includes an array waveform data acquisition module, a dispersion data processing module, a theoretical dispersion curve processing module, a similarity coefficient acquisition module, and a normalization processing module;

[0106] The array waveform data acquisition module controls the signal generator and receiver 1 and the array acoustic logging instrument to obtain array waveform data at a certain depth point;

[0107] The array waveform data acquisition module is used to control the signal generator and receiver 1 and the array acoustic logging instrument to obtain array waveform data at a certain depth point;

[0108] The dispersion data processing module is used to execute step S2;

[0109] The theoretical dispersion curve processing module is used to execute step S3;

[0110] The similarity coefficient acquisition module is used to execute step S4 to perform similarity analysis on the dispersion data of the high-order casing bending mode wave obtained by the dispersion data processing module and the theoretical dispersion curve obtained by the theoretical dispersion curve processing module to obtain a statistical value of the similarity coefficient at a certain depth point; and execute step S5 to control the array waveform data acquisition module, the dispersion data processing module, and the theoretical dispersion curve processing module to obtain a statistical value of the similarity coefficient for the entire depth range;

[0111] The normalization processing module is used to execute step S6 to normalize the statistical value of the similarity coefficient of the entire depth interval;

[0112] The signal generator and receiver 1 is connected to the array acoustic logging instrument through the electronic circuit 2 and is connected to the host computer 3 by signal, and is used to control the array acoustic logging instrument to generate and receive signals, and to perform mutual conversion between digital signals and analog signals;

[0113] The electronic circuit 2 is used to transmit signals;

[0114] The array acoustic logging instrument comprises a plurality of array receiving transducers 4, a sound insulation device 5, and a transmitting transducer 6, and is used to obtain array waveform data at different depth points in the cased well;

[0115] The plurality of array receiving transducers 4 are arranged on the upper portion of the array acoustic logging instrument, and are used to receive dipole signals downhole;

[0116] The sound insulation device 5 is provided below the plurality of array receiving transducers 4 and is used to isolate the direct wave signal propagating along the array acoustic logging instrument;

[0117] The transmitting transducer 6 is disposed below the sound insulation device 5 and is used to excite a dipole signal underground.

[0118] Specifically, the use of the multi-layer cased well quality data inversion device based on dipole acoustic waves includes the following steps:

[0119] The array acoustic logging instrument is placed in the production tubing of the cased well below the derrick 10. The host computer controls the signal generator and the receiver 1 through the software operating system to control the transmitting transducer of the array acoustic logging instrument to excite and generate a dipole signal. The dipole signal reflected by various downhole media is received by the array receiving transducer.

[0120] The electronic circuit transmits the obtained dipole signal to the signal generator and receiver;

[0121] The host computer has a human-computer interaction function, communicates with the signal generator and the receiver, and controls the signal generator and the receiver to perform mutual conversion between digital signals and analog signals through a software operating system;

[0122] The signal generator and receiver transmit the received and converted signals back to the host computer to realize the transmission and collection of downhole acoustic wave signals;

[0123] The software operating system of the host computer processes the collected downhole signals through each step of the dipole acoustic logging cased well quality inversion method to obtain multi-layer cased well quality data;

[0124] Furthermore, the logging results of the dipole acoustic logging and cementing of the multi-layer tubing string are displayed in real time on the host computer.

[0125] Furthermore, the cased well comprises, from inside to outside, a production tubing 7, an inner annulus 8, an inner casing, an outer annulus 9, and an outer casing.

[0126] like Figure 3 As shown, this embodiment is based on embodiments 1 and 2, wherein Figure 3 (a) is a schematic diagram of the tubing-casing model well, in which the outer annulus of the tubing and the outer annulus of the casing are both fluid layers. The cylindrical layers in the cased well are, from the inside to the outside, the following: inner mud layer, inner casing solid layer, inner fluid layer, outer casing solid layer, outer fluid layer, and formation.

[0127] Figure 3 (b) and Figure 3 (c) is a schematic cross-sectional view. Figure 3 (b) In the cross section of the tubing-casing model well, the outer annulus and inner annulus are filled with cement and fluid, respectively. Figure 3 (c) In the cross section of the tubing-casing model well, both the outer annulus and the inner annulus are filled with fluid.

[0128] When performing acoustic logging, the logging instrument is located on the well axis. In theoretical simulation, a point sound source can be used to represent the transmitting and receiving transducers. The frequency dispersion data of the measured array waveform can be obtained by performing spectrum correlation calculation on the array acoustic waveform collected by the receiving transducer.

[0129] Technical effect of this embodiment: The dipole acoustic logging cementing quality device for a multi-layer tubing string provided by this embodiment can collect cementing quality information without removing the production tubing.

[0130] Example 3

[0131] like Figure 4 As shown, this embodiment is the measurement results of a dipole acoustic logging experiment in a double-casing model well based on the dipole acoustic logging cased well quality inversion method and device of embodiment 1 and embodiment 2. Figure 4 (a) and Figure 4 (b) The measured waveforms when the device is used for well-bonded and free casing, respectively. Figure 4 (c) and Figure 4 (d) shows Figure 4 (a) and Figure 4 (b) Frequency-slowness coherence diagram and dispersion curve of the measured waveform, where the solid line is the result of theoretical simulation and the dots are the measured results. Figure 4 In (a), when the bonding is good, there are no statistical points within the error range of the theoretical dispersion curve, and the number of similar points n is 0. Figure 4In (b), the number of blue recording points within the error range of the theoretical dispersion curve for free casing is the n value. Therefore, the size of the n value can reflect the bonding condition of the outer casing. It can be seen that the theoretical and experimental results are in good agreement.

[0132] Technical effect of this embodiment: This embodiment proves that the dipole acoustic logging cementing quality method of the multi-layer tubing string provided by the present invention is feasible for judging the cementing quality of a double-cased well.

[0133] Example 4

[0134] like Figure 5 As shown in the figure, this embodiment is the actual result of calculating the dipole cementing quality index based on the dipole acoustic logging casing well quality inversion method and device in Examples 1-3, wherein the frequency range of the high-order casing bending mode wave obtained is as follows: Figure 5 (a) shows the theoretical dispersion curve, which is represented by the solid line. Figure 5 (b) The line segment is the absolute error s in formula (4) Δ When some experimental data exceed the given absolute error, it is considered that the dispersion at this time is not caused by the lack of bonding on the outer casing, and it does not participate in the calculation of the bonding index during the processing.

[0135] Technical Effects of This Embodiment: This method utilizes the boundary conditions of each layer within a multi-layered tubing string to establish a characteristic matrix, including the acoustic angular frequency matrix of each cylindrical layer within the cased well, the amplitude coefficient of each cylindrical layer within the cased well, and the contributions of radial displacement and radial stress to the direct wave radiated by the sound source. By leveraging the characteristic that the casing bending mode waves corresponding to the tubing and casing have different frequency ranges, the influence of the fluid annulus outside the tubing on the cementing quality results is effectively avoided. Furthermore, by setting a given absolute error, the high-order casing bending mode waves are only sensitive to the cementation of the annulus outside the casing and are less sensitive to formation changes.

[0136] Example 5

[0137] like Figure 6 As shown, the results of the experimental well section processing based on the dipole acoustic logging casing well quality inversion method and device of Examples 1-4 are as follows. The second column is the depth section, the upper half is a well section with an unbonded interface, and the lower half is a well section with a good bonding. During the process of the instrument rising from a well section with a good bonding to a well section with an unbonded interface, since the receiving array has a certain length, the measurement result has a partially bonded well section.

[0138] Column 3 shows the measurement results of the conventional monopole variable density log, which is the measurement result of a single layer of casing after the inner casing is removed.

[0139] The fourth column shows the waveforms of the recording points corresponding to the third column. From the single-layer casing measurement results, it can be seen that the casing wave gradually appears as the instrument rises, indicating that the casing below the well section is well bonded, while the casing interface above the well section is not bonded, which corresponds to the actual situation of the experimental well.

[0140] The CBL logging curve for a single-cased well is shown in column 7 as a solid red line. Columns 5 and 6 show the dipole measurement results for a double-cased well. These results indicate the presence of high-order casing bending mode waves throughout the wellbore, making it difficult to determine cementing quality based solely on the waveforms. The blue solid line in column 7 shows the calculation results of the dipole acoustic wave cementing quality measurement method. It can be seen that the dipole-based cementing quality test results for the double-cased well are highly consistent with the CBL logging results for the single-cased well, and are consistent with the actual situation.

[0141] Column 8 shows the results of the instrument's dispersion processing of high-order casing bending mode waves at a certain depth when the cementation is good, partially cemented, and one interface is uncemented. The pink solid line is the theoretical dispersion curve, and the blue circle is the experimentally extracted dispersion curve. It can be seen that as the cementation quality deteriorates, the high-order casing bending mode waves gradually become stronger, and their corresponding quality index also gradually increases, which is consistent with the results in column 7.

[0142] Column 9 shows a schematic diagram of the tool positions at different well sections, corresponding to the results shown in column 8.

[0143] Technical effect of this embodiment: The combination of theory and experiment in this embodiment proves the feasibility and accuracy of this method in multi-layer tubing cementing quality detection.

[0144] The foregoing description is merely a preferred embodiment of the present invention and does not limit the scope of protection of the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any variation, modification, replacement, integration, or parameter change to these embodiments, which is within the spirit and principles of the present invention and which achieves the same functionality through conventional substitutions, without departing from the principles and spirit of the present invention, falls within the scope of protection of the present invention.

Claims

1. A dipole acoustic logging cased hole quality inversion method, characterized in that: The following steps are involved: S1. Perform dipole acoustic logging in a cased well to obtain array waveform data at a certain depth point; S2. Process the dipole array waveform using the frequency-slowness correlation method to obtain the dispersion data of the high-order casing bending mode wave; S3. Calculate the theoretical dispersion curves of high-order casing bending mode waves in multi-layer tubing strings; S4. Perform similarity analysis on the dispersion data of the high-order casing bending mode wave in step S2 and the theoretical dispersion curve calculated in step S3. Specifically, the statistical value of the similarity coefficient at a certain depth point is obtained by using the dispersion data of the high-order casing bending mode wave in step S2 and the theoretical dispersion curve calculated in step S3. The similarity degree formula for calculating the statistical value of the similarity coefficient can be expressed as: Where n represents the number of similar points; if represents whether the judgment condition is met, ρ represents the correlation coefficient of the dispersion data obtained in step S2; f represents frequency, F is the frequency range of processing, s represents slowness, S is the slowness range of processing, ρ t represents the extraction threshold of the correlation coefficient; ρ max Indicates that the maximum value of the correlation coefficient extraction threshold is obtained at a certain frequency; s t Indicates the range threshold of the absolute error of the slowness value; S Δ represents the absolute error between the processed slowness value and the theoretical slowness value, where the theoretical slowness value is obtained from the theoretical dispersion curve calculated in step S3; S5, repeating steps S1 to S4 to obtain the similarity coefficient of the entire depth range; S6. Normalize the similarity coefficient obtained in step S5 to obtain the cementation index of the entire well section.

2. The dipole acoustic logging cased hole quality inversion method according to claim 1, characterized in that: In step S2, the spectrum correlation method is used to calculate the dispersion data of the measured array waveform. The correlation coefficient calculation formula of the dispersion data is: Where N is the number of array receivers; the intermediate quantity z = exp(-iωsd); ω is the acoustic angular frequency, i is the imaginary unit; s is the inverted slowness value; d is the receiver spacing; X n (ω) represents the frequency spectrum of a certain sound wave phase; * represents the complex conjugate of the function.

3. The dipole acoustic logging cased hole quality inversion method according to claim 1, characterized in that: The step S3 comprises: S31. Establish a characteristic matrix using the boundary conditions of each layer of media in a multi-layer tubing well: Among them, T is the acoustic angular frequency matrix of the cylindrical layer in the cased well, its superscript represents the serial number of the cylindrical layer in the well, and its subscript represents the cylindrical layer in the cased well: Mud is the mud layer, Solid is the inner and outer casing solid layer, Fluid is the fluid layer in the inner and outer annuli, and Formation is the formation matrix. The expression of each layer matrix includes the wave equation and boundary conditions of the elastic medium in the cylindrical coordinate system of the cylindrical layer in the cased well; O represents the zero matrix, and its subscript represents the matrix size; the vector X is the amplitude coefficient of each cylindrical layer in the cased well, its superscript represents the serial number of the cylindrical layer in the well, and its subscript represents each cylindrical layer in the cased well; the radial displacement on the right side of the equation is and radial stress It represents the direct wave radiated from the sound source to the well wall; S32. Calculate the theoretical dispersion curve of the cased well dipole high-order casing bending mode wave using the dispersion equation: det(M(ω, k))=0 (3) Where M represents the characteristic matrix in equation (2), ω is the angular frequency, and k is the wave number.

4. The dipole acoustic logging cased hole quality inversion method according to claim 1, characterized in that: In the step S4, determining whether the condition is met in the similarity point number statistics includes the following steps: S41. When counting the number of similar points n, determine the extraction threshold ρ of the correlation coefficient of the dispersion data t , when the correlation coefficient at a certain frequency is greater than the threshold and is the maximum value ρ at that frequency max When , the dispersion point corresponding to the correlation coefficient of the dispersion data can be recorded; S42. Determine the range threshold s of the absolute error of the slowness value t , when the absolute error s between the slowness value of the dispersion point recorded in step S41 and the theoretical slowness value Δ When it is less than the threshold, the frequency dispersion point can be regarded as a statistical point; S43. Record all statistical points within the frequency range to determine the number n of similar points.

5. A dipole acoustic logging cased hole quality inversion method according to any one of claims 2 to 4, characterized in that: The step S5 includes: after obtaining the statistical value of the similarity coefficient of a certain depth point in step S4, continuing to repeat steps S1 to S4 for the remaining depth points of the cased well to obtain the statistical value of the similarity coefficient of the entire depth range.

6. A dipole acoustic logging cased hole quality inversion method according to claim 5, characterized in that: In step S6, normalization processing is performed based on the statistical value n of the similarity coefficient of all recording points in the well section. The normalized value is the cementation index index for judging the quality of dipole cementing. The cementation index is calculated as follows: where n min is the minimum number of similar points; n max is the maximum number of similar points.

7. A dipole acoustic logging cased hole quality inversion device for executing the method according to any one of claims 1 to 6, characterized in that: The device includes an array acoustic logging instrument and a surface control system; The ground control system includes a signal generator and receiver (1), an electronic circuit (2), and a host computer (3); The host computer (3) is equipped with a software operating system, which includes an array waveform data acquisition module, a dispersion data processing module, a theoretical dispersion curve processing module, a similarity coefficient acquisition module, and a normalization processing module; The array waveform data acquisition module controls the signal generator, receiver and array acoustic logging instrument to obtain array waveform data at a certain depth point; The array waveform data acquisition module is used to obtain array waveform data at a certain depth point; The dispersion data processing module is used to execute step S2 on the downhole signal converted by the signal generating and receiving module; The theoretical dispersion curve processing module is used to execute step S3; The similarity coefficient acquisition module is used to execute steps S4 and S5; The normalization processing module is used to execute step S6; The signal generator and receiver (1) are connected to the array acoustic logging instrument via the electronic circuit (2) and are signal-connected to the host computer (3) for controlling the array acoustic logging instrument to generate and receive signals, and to perform mutual conversion between digital signals and analog signals; The electronic circuit (2) is used to transmit signals; The array acoustic logging instrument comprises a plurality of array receiving transducers (4), a sound insulation device (5), and a transmitting transducer (6), and is used to obtain array waveform data at different depth points in the cased well; A plurality of array receiving transducers (4) are arranged on the upper part of the array acoustic logging instrument and are used to receive dipole signals downhole; The sound insulation device (5) is arranged below the plurality of array receiving transducers (4) and is used to isolate the direct wave signal propagating along the array acoustic logging instrument; The transmitting transducer (6) is arranged below the sound insulation device (5) and is used to excite a dipole signal underground.

8. An electronic device, characterized in that: include: processor; Memory; and a computer program, wherein the computer program is stored in the memory, and the computer program includes instructions, which, when executed by the processor, enable the electronic device to perform the method according to any one of claims 1 to 6.

9. A computer-readable storage medium, characterized in that The computer-readable storage medium includes a stored program, wherein when the program is executed, the device where the computer-readable storage medium is located is controlled to execute the method according to any one of claims 1 to 6.

Images