Method, device, system and medium for calculating casing thickness

Abstract

The present invention provides a method, device, system and medium for calculating casing thickness. By reading the frequency value of the "center of mass" position of the entire frequency-trapped area and substituting it into the thickness calculation formula, the accurate casing thickness can be obtained, and the casing thickness calculation is completed, which reduces the error of casing thickness calculation in the prior art and reduces the steps of casing thickness calculation. At the same time, accurate thickness parameters are provided for subsequent cement bonding quality evaluation. The present application is simple to operate and accurate in calculation, and can be widely used in the field of casing damage detection technology.

Description

Technical Field

[0001] The invention belongs to the technical field of downhole petroleum casing damage detection, and in particular relates to a method, equipment, system and medium for calculating casing thickness. Background Art

[0002] Pulse-echo logging uses a broadband pulse centered near the casing's resonant frequency to excite vibrations through the casing's thickness. The casing absorbs a small portion of the energy and reflects the remainder. The travel time of the reflected wave can be used to calculate the distance from the transducer to the casing's inner wall, thereby assessing casing deformation.

[0003] The frequency of energy absorption is determined by the thickness of the casing, allowing the thickness to be calculated. The current method for calculating casing thickness directly reads the frequency at the minimum value of the "frequency trap" to calculate the thickness, which results in large errors. After the calculation is completed, a correction value must be used to adjust the thickness, but this still results in large errors. Summary of the Invention

[0004] In view of the problems existing in the prior art, the present invention provides a method, device, system and medium for calculating the thickness of the casing, which are simple to operate and can accurately calculate the thickness of the casing.

[0005] The present invention is achieved through the following technical solutions:

[0006] A method for calculating casing thickness, characterized by comprising the following steps:

[0007] S1: Use an ultrasonic transducer with a specific frequency and bandwidth to emit pulsed longitudinal waves. The sound waves hit the inner wall of the casing and enter the casing. The sound waves are continuously attenuated and reflected between the inner and outer walls of the casing to form resonant waves.

[0008] S2: Use Fourier transform to quickly calculate the resonance wave to obtain the waveform spectrum and the frequency trap position of the pipe sleeve resonance wave;

[0009] S3: Calculate the thickness of the casing according to the frequency value corresponding to the centroid position of the frequency trap region of the casing resonance wave.

[0010] Furthermore, the sound wave used in step S1 is a pulse longitudinal wave generated by exciting a self-transmitting and self-receiving ultrasonic transducer that is perpendicular to the inner wall of the casing.

[0011] Furthermore, the pulse echo in step S1 is excited by a flat-plate or focused ultrasonic transducer of a specific frequency and bandwidth, and the transducer is kept perpendicular to the inner wall of the casing.

[0012] Furthermore, the frequency bandwidth of the ultrasonic transducer in step S1 should cover the center frequency required for actual casing resonance wave excitation.

[0013] Furthermore, the centroid position of the frequency trap of the pipe-jacket resonance wave in step S3 is obtained by reading the frequency value at half the area of ​​the closed region of the frequency trap.

[0014] Furthermore, the calculation formula for the casing thickness in step S3 is:

[0015]

[0016] Where D case is the casing thickness, v case is the longitudinal wave sound velocity of the casing, and f is the frequency value corresponding to the center of mass of the frequency trap.

[0017] Furthermore, it is characterized in that the v case The value used is 5900m / s.

[0018] A device for calculating casing thickness, characterized in that, according to a method for calculating casing thickness, it includes:

[0019] A pulse longitudinal wave transmitting module is used to stimulate and generate pulse longitudinal waves;

[0020] Resonance wave acquisition module, used to collect pulse echoes generated by impact with the pipe sleeve;

[0021] The resonance wave calculation module is used to use Fourier transform to quickly calculate the pulse echo to obtain the waveform spectrum and the frequency trap position of the pipe sleeve resonance wave;

[0022] The casing thickness calculation module is used to calculate the casing thickness value according to the frequency value corresponding to the centroid position of the frequency trap of the casing pulse echo.

[0023] A computer device comprises a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the method for calculating casing thickness when executing the computer program.

[0024] A computer-readable storage medium stores a computer program, wherein the computer program implements the steps of the method for calculating casing thickness when executed by a processor.

[0025] Compared with the prior art, the present invention has the following beneficial technical effects:

[0026] The present invention provides a method, device, system and medium for calculating casing thickness. By reading the frequency value of the "center of mass" position of the entire frequency-trapped area and substituting it into the thickness calculation formula, the accurate casing thickness can be obtained, and the casing thickness calculation is completed, which reduces the error of casing thickness calculation in the prior art and reduces the steps of casing thickness calculation. At the same time, accurate thickness parameters are provided for subsequent cement bonding quality evaluation. The present application is simple to operate and accurate in calculation, and can be widely used in the field of casing damage detection technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a flow chart of a method for calculating casing thickness in a specific embodiment of the present invention;

[0028] Figure 2 Schematic diagram of vertical incidence, reflection, and transmission of sound waves in four layers of parallel media in a specific embodiment of the present invention;

[0029] Figure 3 A schematic diagram of a pulse echo waveform in a specific embodiment of the present invention;

[0030] Figure 4 This is a spectrum diagram obtained by Fourier transform calculation of the pulse echo waveform in a specific embodiment of the present invention;

[0031] Figure 5 Schematic diagram showing how the pulse echo frequency notch area changes with changes in cement sheath medium properties in a specific embodiment of the present invention;

[0032] Figure 6 The casing thickness value is obtained by calculating the laboratory test data according to the calculation method of the present invention in a specific embodiment of the present invention. DETAILED DESCRIPTION

[0033] The present invention will be further described in detail below with reference to specific embodiments, which are intended to explain the present invention rather than to limit it.

[0034] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0035] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0036] The present invention provides a method for calculating the thickness of the casing. Figure 1 As shown, the following steps are included:

[0037] S1: Use an ultrasonic transducer with a specific frequency and bandwidth to emit pulsed longitudinal waves. The sound waves hit the inner wall of the casing and enter the casing. The sound waves are continuously attenuated and reflected between the inner and outer walls of the casing to form resonant waves.

[0038] Specifically, in step S1, after the sound wave hits the inner wall of the casing and enters the casing, it is necessary to determine whether a resonance wave is generated. If no resonance wave is generated, a null value is returned; if a resonance wave is generated, the calculation of step S2 is performed;

[0039] Further, such as Figure 3 As shown, Figure 3 The waveform is the full wave of the pulse echo waveform received in actual logging, which consists of three parts: the main reflection wave, the resonance wave, and the second interface echo. The resonance wave is the exponentially decaying wave behind the main reflection wave. These three waves are aliased in the time domain.

[0040] S2: Use Fourier transform to quickly calculate the resonance wave to obtain the waveform spectrum and the frequency trap position of the pipe sleeve resonance wave. Specifically, Figure 4 As shown;

[0041] S3: Calculate the thickness of the casing according to the frequency value corresponding to the centroid position of the frequency trap region of the casing resonance wave.

[0042] A preferred embodiment provided by the present invention is that the sound wave used in step S1 is a pulse longitudinal wave generated by exciting a self-emitting and self-receiving ultrasonic transducer that is perpendicular to the inner wall of the casing; further, the pulse echo in step S1 is excited by a flat-plate or focused ultrasonic transducer of a specific frequency and bandwidth, and the transducer must be perpendicular to the inner wall of the casing; further, the frequency bandwidth range of the ultrasonic transducer in step S1 must cover the center frequency required for the actual casing resonance wave excitation.

[0043] Furthermore, the centroid position of the frequency trap of the pipe-jacket resonance wave in step S3 is obtained by reading the frequency value at half the area of ​​the closed region of the frequency trap.

[0044] Furthermore, the calculation formula for the casing thickness in step S3 is:

[0045]

[0046] Where D case is the casing thickness, v case is the longitudinal wave speed of the casing, and f is the frequency value corresponding to the center of mass.

[0047] Furthermore, the v case is 5900 m / s; specifically, the casing longitudinal wave sound velocity during the actual calculation can be obtained by taking the actual sound velocity of the actual casing material during actual measurement. This value can be the empirical value of the casing velocity in the oil field block, or it can be obtained by using a standard transducer according to the transmission sound velocity measurement method or other sound velocity measurement methods.

[0048] The present invention provides an embodiment as follows: Figure 2 As shown, there are four dielectric layers, including dielectric 1, dielectric 2, dielectric 3 and dielectric 4;

[0049] The medium 1 is water; the medium 2 is a casing with a thickness of 12 mm; the medium 3 is cement with a thickness of 30 mm and a density of 1.5 g / cm;

[0050] The pulse echo probe is used to collect echo data at 160 points. According to the calculation results of the present invention, the actual casing thickness value at 160 points is 12 mm. Figure 6 As shown, the error with the actual casing thickness is 0, as shown in Figure 5 As shown in the figure, the changes of cement acoustic impedance, cement longitudinal wave velocity and cement sheath thickness after casing are shown in the figure.

[0051] In another embodiment of the present invention, a computer device is provided, comprising a processor and a memory, wherein the memory is configured to store a computer program, the computer program including program instructions, and the processor is configured to execute the program instructions stored in the computer storage medium. The processor may be a central processing unit (CPU), or may be another general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. It is the computing core and control core of the terminal, and is suitable for implementing one or more instructions, specifically for loading and executing one or more instructions in the computer storage medium to implement a corresponding method flow or corresponding function. The processor described in this embodiment of the present invention can be used in the operation of a method for calculating casing thickness.

[0052] In another embodiment of the present invention, a storage medium is provided, specifically a computer-readable storage medium (Memory). The computer-readable storage medium is a memory device in a computer device, used to store programs and data. It is understood that the computer-readable storage medium herein may include both built-in storage media in the computer device and, of course, extended storage media supported by the computer device. The computer-readable storage medium provides storage space, which stores the terminal's operating system. Furthermore, the storage space also stores one or more instructions suitable for being loaded and executed by a processor. These instructions may be one or more computer programs (including program code). It should be noted that the computer-readable storage medium herein may be a high-speed RAM memory or a non-volatile memory, such as at least one disk storage device. The processor may load and execute the one or more instructions stored in the computer-readable storage medium to implement the corresponding steps of the method for calculating casing thickness in the above-mentioned embodiment.

[0053] It will be understood by those skilled in the art that embodiments of the present invention may be provided as methods, systems, or computer program products. Thus, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment, or an embodiment combining software and hardware. Furthermore, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0054] The present invention is described with reference to flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowcharts and / or block diagrams, as well as combinations of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowcharts and / or block diagrams. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0055] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0056] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A step that specifies a function in one or more boxes.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for calculating casing thickness, characterized in that: The following steps are involved: S1: Use an ultrasonic transducer with a specific frequency and bandwidth to emit pulsed longitudinal waves. The sound waves hit the inner wall of the casing and enter the casing. The sound waves are continuously attenuated and reflected between the inner and outer walls of the casing to form resonant waves. S2: Use Fourier transform to quickly calculate the resonance wave to obtain the waveform spectrum and the frequency trap position of the pipe sleeve resonance wave; S3: Calculate the thickness of the casing according to the frequency value corresponding to the centroid position of the frequency trap region of the casing resonance wave.

2. A method for calculating casing thickness according to claim 1, characterized in that: The sound wave used in step S1 is a pulse longitudinal wave generated by exciting a self-transmitting and self-receiving ultrasonic transducer that is perpendicular to the inner wall of the casing.

3. The method for calculating casing thickness according to claim 1, characterized in that: The pulse echo in step S1 is excited by a flat-plate or focused ultrasonic transducer of a specific frequency and bandwidth, and the transducer must be kept perpendicular to the inner wall of the casing.

4. The method for calculating casing thickness according to claim 1, characterized in that: The frequency bandwidth of the ultrasonic transducer in step S1 should cover the center frequency required for the actual casing resonance wave excitation.

5. The method for calculating casing thickness according to claim 1, characterized in that: The centroid position of the frequency notch of the pipe-shroud resonance wave in step S3 is obtained by reading the frequency value at half the area of ​​the closed region of the frequency notch.

6. The method for calculating casing thickness according to claim 1, characterized in that: The calculation formula of the casing thickness in step S3 is: Where D case is the casing thickness, v case is the longitudinal wave sound velocity of the casing, and f is the frequency value corresponding to the center of mass of the frequency trap.

7. A method for calculating casing thickness according to claim 6, characterized in that: The v case The value used is 5900m / s.

8. A device for calculating casing thickness, characterized in that: The device executes the method for calculating casing thickness according to any one of claims 1 to 5, comprising: A pulse longitudinal wave transmitting module is used to stimulate and generate pulse longitudinal waves; Resonance wave acquisition module, used to collect pulse echoes generated by impact with the pipe sleeve; The resonance wave calculation module is used to use Fourier transform to quickly calculate the pulse echo to obtain the waveform spectrum and the frequency trap position of the pipe sleeve resonance wave; The casing thickness calculation module is used to calculate the casing thickness value according to the frequency value corresponding to the centroid position of the frequency trap of the casing pulse echo.

9. A computer device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the computer program, the steps of the method for calculating casing thickness according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of the method for calculating casing thickness according to any one of claims 1 to 7 are implemented.

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