Fiber optic ultrasonic based acoustic wave logging physics simulation system

Abstract

This invention discloses a physical simulation system for acoustic logging based on fiber optic ultrasound, comprising an acoustic logging physical model, a pulsed laser, a laser transmission line, an ultrasonic exciter, a fiber optic sensor, a signal transmission line, and a signal demodulator. The acoustic logging physical model has a through-hole at its axial center, and the ultrasonic exciter and fiber optic sensor are disposed inside the through-hole. The pulsed laser emits pulsed laser light, which is transmitted to the ultrasonic exciter via the laser transmission line. The ultrasonic exciter excites ultrasonic waves, which propagate within the through-hole. The signal demodulator emits sensing light, which is transmitted to the fiber optic sensor via the signal transmission line. The ultrasonic waves modulate the optical signal, which is then transmitted back to the signal demodulator via the signal transmission line. The signal demodulator acquires, processes, and analyzes the modulated optical signal. This invention combines laser ultrasound technology with fiber optic sensing technology to achieve optically enhanced ultrasonic excitation and detection.

Description

Technical Field

[0001] This invention belongs to the field of acoustic logging physical simulation technology, specifically relating to an acoustic logging physical simulation system based on fiber optic ultrasound. Background Technology

[0002] my country's energy development is currently in a phase of accelerating the construction of a new energy system. Sonic logging, as a geophysical parameter measurement method based on the acoustic characteristics of rock formations, provides crucial support for optimizing exploration and development strategies and improving resource extraction efficiency. With the increasingly deteriorating quality of oil and gas resources, exploration and development in ultra-deep, low-permeability, unconventional, and old oilfields are rapidly becoming the main focus. Complex well structures and well condition operations are also showing a trend towards standardization and normalization, posing new requirements and challenges to sonic logging technology serving geology and engineering. Therefore, it is urgent to deepen the basic research and applied practice of sonic logging, and actively carry out innovative experimental simulation research based on sonic logging physical models to improve the adaptability of logging technology to the exploration and development of "deep, low-permeability, unconventional, and old" oil and gas resources.

[0003] Sonic logging physical simulation is a technique that uses ultrasonic methods in a laboratory to simulate the acoustic field characteristics of a wellbore in the field, creating a physical model (i.e., a model well) based on a similarity factor. It falls under the fundamental research category of elastic wave physical simulation and provides theoretical and methodological guidance for improving energy prediction and evaluation. Sonic logging physical simulation requires embedding an ultrasonic transducer within the model well to perform ultrasonic transmission and reception. Due to limitations in transducer size and responsivity, existing similarity factor settings are generally low (e.g., 10, meaning a smaller size and higher frequency compared to the experimental setup) to generate a well diameter of a few centimeters to match the large diameter of the transducer. Therefore, sonic logging physical simulation exhibits large-scale characteristics (model wells reaching meter-level dimensions), leading to problems such as extremely large system scale, difficulties in experimental operation and model control, and insufficient similarity. Furthermore, conventional transducers are all piezoelectric ceramic electrical devices, which suffer from drawbacks such as a single excitation / response mode, narrow bandwidth, difficulty in multiplexing, and insufficient stability and reliability. Signal amplification and superposition denoising methods are required to improve the signal-to-noise ratio, making it difficult to achieve high-precision, high-accuracy, and multi-scenario acoustic logging experimental simulation measurements. Therefore, there is an urgent need to seek new mechanisms for physical simulation of acoustic logging and new ultrasonic detection technologies to overcome the limitations of existing physical simulation experiments in areas such as similarity scale factor customization, model well establishment, ultrasonic transduction, and wellbore feature acquisition. Summary of the Invention

[0004] To address the aforementioned problems in the existing technology, this invention provides a physical simulation system for acoustic logging based on fiber optic ultrasound. The technical problem to be solved by this invention is achieved through the following technical solution: One aspect of the present invention provides a physical simulation system for acoustic logging based on fiber optic ultrasound, comprising an acoustic logging physical model, a pulsed laser, a laser transmission line, an ultrasonic exciter, a fiber optic sensor, a signal transmission line, and a signal demodulator, wherein... The acoustic logging physical model has a through hole at its axial center, and the ultrasonic exciter and the fiber optic sensor are coaxially arranged inside the through hole. The pulsed laser and the signal demodulator are disposed outside the acoustic logging physical model. The pulsed laser is connected to the ultrasonic exciter through the laser transmission line. The pulsed laser is used to emit pulsed laser light and transmit it to the ultrasonic exciter through the laser transmission line. The ultrasonic exciter uses the pulsed laser light to excite ultrasonic waves and emits the ultrasonic waves into the through hole. The signal demodulator is connected to the fiber optic sensor via the signal transmission line. The signal demodulator is used to emit sensing light and transmit it to the interior of the through hole through the signal transmission line and the fiber optic sensor. It also returns the ultrasonically modulated optical signal to the signal demodulator via the fiber optic sensor and the signal transmission line. The signal demodulator is used to acquire, process, and analyze the received modulated optical signal.

[0005] In one embodiment of the present invention, the acoustic logging physical simulation system based on fiber optic ultrasound further includes a displacement stepping device, which is used to drive the ultrasonic exciter and the fiber optic sensor to move synchronously along the central axis of the acoustic logging physical model.

[0006] In one embodiment of the present invention, the ultrasonic exciter and the fiber optic sensor are respectively disposed at both ends inside the through hole along the axial direction, the pulsed laser is disposed outside the through hole at one end of the ultrasonic exciter, and the signal demodulator is disposed outside the through hole at one end of the fiber optic sensor.

[0007] In one embodiment of the present invention, the number of ultrasonic exciters is one or more. When the number of ultrasonic exciters is multiple, the multiple ultrasonic exciters are respectively connected to the pulsed laser through the laser transmission line, and the multiple ultrasonic exciters can excite ultrasonic waves sequentially or simultaneously.

[0008] In one embodiment of the present invention, the number of optical fiber sensors is one or more. When the number of optical fiber sensors is multiple, the multiple optical fiber sensors are respectively connected to the signal demodulator through the signal transmission line. The multiple optical fiber sensors can receive the ultrasonically modulated optical signal synchronously or in a time-division manner.

[0009] In one embodiment of the present invention, the optical fiber ultrasonic-based acoustic logging physical simulation system further includes a rotary stepping device, which drives the ultrasonic exciter and the optical fiber sensor to rotate synchronously around the central axis of the acoustic logging physical model.

[0010] In one embodiment of the present invention, the ultrasonic exciter and the fiber optic sensor are arranged parallel to each other on the central axis of the through hole, and the pulsed laser and the signal demodulator are arranged on the same side of the through hole.

[0011] Another aspect of the present invention provides a physical simulation system for acoustic logging based on fiber optic ultrasound, comprising an acoustic logging physical model, a self-transmitting light source and demodulation module, a self-transmitting transmission line, and an ultrasonic self-transmitting module, wherein... The acoustic logging physical model has a through hole in the center along the axial direction. The ultrasonic self-transmitting module is located inside the through hole and on the central axis of the through hole (11). The self-transmitting light source and demodulation module are located outside the acoustic logging physical model. The self-transmitting light source and demodulation module are connected to the ultrasonic self-transmitting module through the self-transmitting transmission line. The ultrasonic self-transmitting module can rotate around the central axis of the through hole inside the through hole. The self-transmitting light source and demodulation module are used to emit pulsed laser and transmit it to the ultrasonic self-transmitting module through the self-transmitting transmission line. The ultrasonic self-transmitting module uses the pulsed laser to excite ultrasonic waves and emits the ultrasonic waves into the through hole. The self-transmitting light source and demodulation module is also used to emit sensing light and transmit it to the ultrasonic self-transmitting module via the self-transmitting transmission line. The ultrasonic self-transmitting module receives the ultrasonically modulated light signal and transmits it back to the self-transmitting light source and demodulation module via the self-transmitting transmission line. The self-transmitting light source and demodulation module processes and analyzes the ultrasonically modulated light signal.

[0012] In one embodiment of the present invention, the optical fiber ultrasound-based acoustic logging physical simulation system further includes a rotary stepping device, which drives the ultrasonic self-transmitting module to rotate synchronously around the central axis of the acoustic logging physical model.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention proposes a physical simulation system for acoustic logging based on fiber optic ultrasound. It innovatively applies fiber optic ultrasound technology to acoustic logging physical simulation, constructing an optical ultrasound experimental platform based on a high-similarity-scale factor model well. This results in an elastic wave physical simulation with high precision, high reliability, and flexible controllability. A transceiver enhancement method for laser ultrasonic excitation and fiber optic ultrasonic detection is proposed. Micro-probe-type ultrasonic exciters and fiber optic sensors are integrated into millimeter-scale through-holes in the acoustic logging physical model, forming a microstructure fine detection technology with high signal-to-noise ratio, high sensitivity, and strong applicability. This invention significantly reduces the system complexity of acoustic logging physical simulation and effectively improves the wellbore acoustic field resolution capability. It provides fundamental research support for acoustic logging field applications in areas such as logging response laws and evaluation methods, and fully meets the needs of geophysical exploration, non-destructive testing, and health monitoring for the identification and detection of micro-morphological features in confined spaces.

[0014] 2. This invention sets a high similarity scaling factor (not less than 50) to construct a small-scale acoustic logging physical simulation system (the volume of the acoustic logging physical model is <800 cm³). 3 With a through-hole diameter of <5mm, laser ultrasonic technology is introduced, combining a pulsed laser with an ultrasonic exciter (photoacoustic functional material). Optical enhanced ultrasonic technology that integrates fiber optic ultrasonics and fiber optic sensing is used to reconstruct the acoustic field characteristics within the acoustic logging physical model, effectively reducing the complexity of establishing the acoustic logging physical model system and improving the ability to resolve acoustic field characteristics within the through-hole.

[0015] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of a fiber optic ultrasonic-based acoustic logging physical simulation system provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the physical simulation system for acoustic logging that simulates acoustic velocity logging and acoustic amplitude logging, provided in an embodiment of the present invention. Figure 3 This is a schematic diagram of the multi-transmitter combination of ultrasonic exciter and fiber optic sensor for simulated acoustic velocity logging and acoustic amplitude logging provided in an embodiment of the present invention. Figure 4 This is a schematic diagram of the structure of a single-transmitter, single-receiver acoustic logging physical simulation system provided in an embodiment of the present invention; Figure 5 yes Figure 4 A schematic diagram of the profile of a single-transmitter, single-receiver acoustic logging physical simulation system performing well-circumferential spiral scanning imaging. Figure 6 This is a schematic diagram of the structure of a self-transmitting acoustic logging physical simulation system provided in an embodiment of the present invention; Figure 7 yes Figure 6 A schematic diagram of the cross-sectional image of the well perimeter spiral scanning imaging performed by the self-transmitting acoustic logging physical simulation system. Figure 8 This is a general flowchart of various logging methods of the acoustic logging physical simulation system based on fiber optic ultrasound provided in the embodiments of the present invention. Explanation of reference numerals in the attached figures: 1-Sonic logging physical model; 11-Through hole; 2-Pulse laser; 3-Laser transmission line; 4-Ultrasonic exciter; 5-Fiber optic sensor; 6-Signal transmission line; 7-Signal demodulator; 8-Self-transmitting light source and demodulation module; 9-Self-transmitting transmission line; 10-Ultrasonic self-transmitting module. Detailed Implementation

[0017] To further illustrate the technical means and effects adopted by the present invention to achieve the intended purpose, the following detailed description of a fiber optic ultrasonic-based acoustic logging physical simulation system based on the present invention is provided in conjunction with the accompanying drawings and specific embodiments.

[0018] The foregoing and other technical contents, features, and effects of the present invention will be clearly presented in the following detailed description of specific embodiments in conjunction with the accompanying drawings. Through the description of the specific embodiments, a more in-depth and concrete understanding can be gained of the technical means and effects adopted by the present invention to achieve its intended purpose. However, the accompanying drawings are for reference and illustration only and are not intended to limit the technical solutions of the present invention.

[0019] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations are intended to cover non-exclusive inclusion, such that an article or apparatus comprising a list of elements includes not only those elements but also other elements not expressly listed. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the article or apparatus that includes said element.

[0020] Example 1 Please see Figure 1 , Figure 1This is a schematic diagram of a fiber optic ultrasonic-based acoustic logging physical simulation system according to an embodiment of the present invention. The system includes an acoustic logging physical model 1, a pulsed laser 2, a laser transmission line 3, an ultrasonic exciter 4, a fiber optic sensor 5, a signal transmission line 6, and a signal demodulator 7. The acoustic logging physical model 1 has a through-hole 11 at its axial center, and the ultrasonic exciter 4 and the fiber optic sensor 5 are coaxially disposed inside the through-hole 11. The pulsed laser 2 and the signal demodulator 7 are disposed outside the acoustic logging physical model 1, and the pulsed laser 2 is connected to the laser transmission line 3. An ultrasonic exciter 4 and a pulsed laser 2 are used to emit pulsed laser light, which is transmitted to the ultrasonic exciter 4 via a laser transmission line 3. The ultrasonic exciter 4 uses the pulsed laser to excite ultrasonic waves and emits the ultrasonic waves into the through-hole 11. A signal demodulator 7 is connected to an optical fiber sensor 5 via a signal transmission line 6. The signal demodulator 7 emits sensing light, which is transmitted to the inside of the through-hole 11 via the signal transmission line 6 and the optical fiber sensor 5. The ultrasonically modulated optical signal is then returned to the signal demodulator 7 via the optical fiber sensor 5 and the signal transmission line 6. The signal demodulator 7 is used to acquire, process, and analyze the received modulated optical signal. This optical wave logging physical simulation system based on fiber optic ultrasound can realize the physical simulation of optical wave logging using methods such as sound velocity logging, sound amplitude logging, and wellbore spiral scanning imaging.

[0021] In this embodiment, the acoustic logging physical model 1 is an acoustic logging physical model with a high similarity scale factor, greater than 50 compared to the actual well body. It can be fabricated using methods such as 3D printing, artificial casting, or mold pressing, and its interior contains lithological characteristics simulating actual well conditions. A through-hole 11 is used to simulate the actual wellbore, and the diameter of this through-hole 11 is controlled at the millimeter level to ensure precise matching with the dimensions of the ultrasonic exciter 4 and the fiber optic sensor 5, ensuring that the ultrasonic exciter 4 and the fiber optic sensor 5 can be centered. Preferably, the diameter of the through-hole 11 is <5mm. The material of the acoustic logging physical model 1 can be epoxy resin, artificial core material, concrete, or acrylic as the matrix, with the addition of adjusting materials such as quartz sand, barite powder, or fiber cloth to simulate the acoustic characteristics of different lithologies (such as P-wave velocity, S-wave velocity, density, etc.). The overall volume of the acoustic logging physical model 1 enables small-scale, high-precision acoustic logging physical simulation, significantly reducing system complexity.

[0022] In practical use, pulsed laser 2 emits pulsed laser light, which is transmitted to ultrasonic exciter 4 via laser transmission line 3. Ultrasonic exciter 4 arouses ultrasonic waves, which propagate inside the acoustic logging physical model 1, i.e., inside the through-hole 11. Simultaneously, signal demodulator 7 emits sensing light, which is transmitted to fiber optic sensor 5 via signal transmission line 6 and then to the inside of through-hole 11. This sensing light is modulated by the ultrasonic waves inside the acoustic logging physical model 1 within through-hole 11, i.e., its characteristic parameters (such as intensity, phase, frequency, and polarization state) change under the influence of the ultrasonic waves. Subsequently, fiber optic sensor 5 receives the ultrasonically modulated optical signal and transmits it back to signal demodulator 7 via signal transmission line 6. Signal demodulator 7 then collects, processes, and analyzes the signal data.

[0023] Compared to piezoelectric transducers, the pulsed laser 2 used in this embodiment has the advantages of non-contact excitation, wide bandwidth and high resolution, multi-mode excitation capability, high spatiotemporal resolution, fast response and repeatability; the ultrasonic exciter 4 in this embodiment can be made into a miniature probe, which can be used for millimeter-scale through-holes in the acoustic logging physical model 1 with a high similarity scaling factor.

[0024] Further, please see Figure 2 , Figure 2 This is a schematic diagram of a physical simulation system for acoustic logging, simulating acoustic velocity and amplitude logging, provided by an embodiment of the present invention. As shown above, the physical simulation system includes an acoustic logging physical model 1, a pulsed laser 2, a laser transmission line 3, an ultrasonic exciter 4, a fiber optic sensor 5, a signal transmission line 6, and a signal demodulator 7. Furthermore, the system also includes a displacement stepping device (not shown in the diagram), which drives the ultrasonic exciter 4 and the fiber optic sensor 5 to move synchronously axially along the central axis of the acoustic logging physical model 1. In this embodiment, the ultrasonic exciter 4, the fiber optic sensor 5, and the displacement stepping device are coaxially and centrally positioned in the through-hole 11 of the acoustic logging physical model 1 using a fiber optic acoustic traction device (not shown in the diagram). The fiber optic acoustic traction device in this embodiment is a fixing device.

[0025] An ultrasonic exciter 4 and an optical fiber sensor 5 are respectively disposed at opposite ends of the through-hole 11 along the axial direction. A pulsed laser 2 is disposed outside the through-hole 11 at one end of the ultrasonic exciter 4, and a signal demodulator 7 is disposed outside the through-hole 11 at one end of the optical fiber sensor 5. That is to say, as... Figure 2 As shown, the ultrasonic exciter 4 and the fiber optic sensor 5 are located at both ends inside the through hole 11, and are connected to the pulsed laser 2 and the signal demodulator 7 located at both ends of the through hole 11 through the laser transmission line 3 and the signal transmission line 6, respectively.

[0026] In this embodiment, the number of ultrasonic exciters 4 is one or more. When there are multiple ultrasonic exciters 4, each ultrasonic exciter 4 is connected to a pulsed laser 2 via a laser transmission line 3, and the multiple ultrasonic exciters 4 can excite ultrasonic waves sequentially or simultaneously. The number of fiber optic sensors 5 is one or more. When there are multiple fiber optic sensors 5, each fiber optic sensor 5 is connected to a signal demodulator 7 via a signal transmission line 6, and the multiple fiber optic sensors 5 can receive ultrasonically modulated optical signals synchronously or in a time-division manner.

[0027] Please see Figure 3 , Figure 3 This is a schematic diagram of various transceiver combinations of ultrasonic exciter and fiber optic sensor provided in the embodiments of the present invention. By utilizing the multiplexing characteristics of multi-segment excitation of laser ultrasound and fiber optic sensing, and optimizing the matching of ultrasonic transceiver amplitude and frequency characteristics, the acoustic logging physical simulation system of this embodiment can establish various combination forms of ultrasonic exciter 4 and fiber optic sensor 5, such as single-transmit single-receive, dual-transmit dual-receive, and multi-transmit multi-receive, thereby simulating acoustic logging methods such as acoustic velocity logging and acoustic amplitude logging.

[0028] Specifically, such as Figure 8 As shown, the combined configurations used in simulated sonic logging mainly include single-transmitter dual-receiver, dual-transmitter single-receiver, dual-transmitter dual-receiver, and multi-transmitter multi-receiver configurations. These can be achieved by varying the number of ultrasonic exciters 4 and fiber optic sensors 5. For example, when the sonic logging physical simulation system includes one ultrasonic exciter 4 and one fiber optic sensor 5, a single-transmitter single-receiver mode is formed; when the system includes one ultrasonic exciter 4 and two fiber optic sensors 5, a single-transmitter dual-receiver mode is formed; when the system includes multiple ultrasonic exciters 4 and multiple fiber optic sensors 5, a multi-transmitter multi-receiver mode is formed, and so on. During simulated sonic logging, the fiber optic sensors 5 sequentially receive the ultrasonic waves propagating in the sonic logging physical model 1. The time difference in ultrasonic wave propagation reflects the formation sound velocity, which can be used to estimate porosity, identify reservoirs, and study lithology.

[0029] The simulated acoustic amplitude logging primarily uses a single-transmitter, single-receiver combination to measure the amplitude changes of ultrasonic waves. As ultrasonic waves propagate in the acoustic logging physical model 1, their energy is gradually absorbed. Therefore, the formation properties and cementation can be understood through the attenuation of the ultrasonic wave amplitude (reflected by changes in the optical signal modulated by the ultrasonic wave).

[0030] The ultrasonic exciter 4 in this embodiment can be made of various materials, including but not limited to MXenes, carbon-based materials, and other high-efficiency photoacoustic functional materials. The fiber optic sensor 5 can be of various types, including but not limited to fiber grating ultrasonic sensors and interferometric fiber optic ultrasonic sensors (Mach-Zehnder interferometers, Fabry-Perot interferometers, etc.). Both the ultrasonic exciter 4 and the fiber optic sensor 5 can be fabricated as miniature probes.

[0031] In practice, for the multi-transmitter, multi-receiver mode, firstly, all ultrasonic exciters 4, fiber optic sensors 5, and displacement stepping devices are placed into the through-hole to a predetermined depth according to the required transmit / receive combination mode using a fiber optic acoustic traction device. This ensures that all microprobes are centered and have uniform spacing from the well wall. The displacement stepping device then drives all ultrasonic exciters 4 and fiber optic sensors 5 within the through-hole 11 to move synchronously. The pulsed laser 2 can emit laser pulses to multiple ultrasonic exciters sequentially or simultaneously according to a preset time sequence. Each exciter independently generates ultrasonic waves, which propagate within the acoustic logging physical model 1. Simultaneously, the signal demodulator 7 emits sensing light, which enters the through-hole via the signal transmission line 6 and different fiber optic sensors 5. Subsequently, multiple fiber optic sensors synchronously or time-divisionally receive the ultrasonically modulated light signals, which are then transmitted back to the signal demodulator 7 via the signal transmission line 6. The signal demodulator 7 records the light signals received by each fiber optic sensor and records the corresponding parameters: arrival time, amplitude, and waveform characteristics. Furthermore, the signal demodulator 7 can combine the time difference of the ultrasonically modulated optical signal arriving at different fiber optic sensors 5, as well as the amplitude and waveform differences arriving at the same fiber optic sensor 5, to comprehensively demodulate key parameters such as formation sound velocity and porosity, and analyze the formation's physical characteristics. It can also adjust the depth positions of the ultrasonic exciter 4 and the fiber optic sensor 5 through a displacement stepping device, enabling signal acquisition at multiple depths and obtaining multiple sets of acoustic waveform data. The multi-transmitter, multi-receiver combination utilizes the advantages of multi-segment excitation of laser ultrasound and multi-channel multiplexing of fiber optic sensing to achieve high-precision, high-redundancy acoustic logging physical simulation.

[0032] Example 2 Based on Embodiment 1, this embodiment provides another acoustic logging physical simulation system based on fiber optic ultrasound, including an acoustic logging physical model 1, a pulsed laser 2, a laser transmission line 3, an ultrasonic exciter 4, a fiber optic sensor 5, a signal transmission line 6, and a signal demodulator 7. It also includes a rotary stepping device (not shown in the figures), which drives the ultrasonic exciter 4 and the fiber optic sensor 5 to rotate synchronously around the central axis of the acoustic logging physical model 1. In this embodiment, the ultrasonic exciter 4, the fiber optic sensor 5, and the rotary stepping device are coaxially and centrally inserted into the through-hole 11 of the acoustic logging physical model 1 using a fiber optic acoustic traction device.

[0033] Please see also Figure 4 and Figure 5, Figure 4 This is a schematic diagram of the structure of a single-transmitter, single-receiver acoustic logging physical simulation system provided in an embodiment of the present invention; Figure 5 yes Figure 4 A schematic diagram of the profile of a single-transmitter, single-receiver acoustic logging physical simulation system performing well-circumferential spiral scanning imaging. Figure 5 This demonstrates a single-transmitter, single-receiver combination of an ultrasonic exciter 4 and an optical fiber sensor 5 within a through-hole 11. In this embodiment, the ultrasonic exciter 4 and the optical fiber sensor 5 are arranged parallel to each other on the central axis of the through-hole 11, and the pulsed laser and the signal demodulator 7 are located on the same side of the through-hole 11. That is, the ultrasonic exciter 4 and the optical fiber sensor 5 are located at the same end inside the through-hole 11, and are connected to the pulsed laser 2 and the signal demodulator 7, located on the same side outside the through-hole 11, respectively, via laser transmission line 3 and signal transmission line 6.

[0034] In this embodiment, the wellbore spiral scanning imaging is based on the pulse-echo method. The acoustic logging physical model 1 is circumferentially rotated and scanned within the through hole 11 to record the acoustic wave reflection amplitude and propagation time information, reconstruct the wellbore multidimensional image of the acoustic logging physical model, and complete the analysis and research on the acoustic logging response law.

[0035] Specifically, such as Figure 8 As shown, a rotating stepping device drives the ultrasonic exciter 4 and fiber optic sensor 5 inside the through-hole 11 to rotate synchronously. The pulsed laser 2 emits pulsed laser light, which is transmitted to the ultrasonic exciter 4 via the laser transmission line 3, generating ultrasonic waves through a photo-induced ultrasonic effect. These waves propagate within the acoustic logging physical model 1. The signal demodulator 7 emits sensing light, which is transmitted to the fiber optic sensor 5 via the signal transmission line 6 and then to the interior of the through-hole 11. This sensing light is modulated by the ultrasonic waves within the acoustic logging physical model 1 inside the through-hole 11, causing changes in characteristic parameters (such as intensity, phase, frequency, and polarization state) under the influence of the ultrasonic waves. Subsequently, the fiber optic sensor 5 receives the ultrasonically modulated light signal and transmits it back to the signal demodulator 7 via the signal transmission line 6. The signal demodulator 7 completes the acquisition, processing, and analysis of signal data within the acoustic logging physical model 1, achieving high signal-to-noise ratio demodulation. Based on information such as profile reflection amplitude and propagation time, it can reconstruct a multi-dimensional image around the well and analyze and evaluate the microstructural features of the acoustic logging physical model 1.

[0036] Example 3 This embodiment provides another acoustic logging physical simulation system based on fiber optic ultrasound. Please refer to [link to relevant documentation]. Figure 6 and Figure 7 , Figure 6 This is a schematic diagram of the structure of a self-transmitting acoustic wave logging physical simulation system provided in an embodiment of the present invention; Figure 7 yes Figure 6A schematic diagram of a cross-sectional view of a self-transmitting acoustic logging physical simulation system performing well-circumferential spiral scanning imaging. This fiber-optic ultrasonic-based acoustic logging physical simulation system includes an acoustic logging physical model 1, a self-transmitting light source and demodulation module 8, a self-transmitting transmission line 9, and an ultrasonic self-transmitting module 10. The acoustic logging physical model 1 has a through-hole 11 at its center along the axial direction. The ultrasonic self-transmitting module 10 is located inside the through-hole 11 and on its central axis. The self-transmitting light source and demodulation module 8 is located outside the acoustic logging physical model 1 and is connected to the ultrasonic self-transmitting module 10 via the self-transmitting transmission line 9. The ultrasonic self-transmitting module 10 can rotate within the through-hole 11... The central axis of the through hole 11 rotates; the self-transmitting light source and demodulation module 8 is used to emit pulsed laser light and transmit it to the ultrasonic self-transmitting module 10 through the self-transmitting transmission line 9. The ultrasonic self-transmitting module 10 uses the pulsed laser light to excite ultrasonic waves, which propagate inside the through hole 11; the self-transmitting light source and demodulation module 8 is also used to emit sensing light and transmit it to the ultrasonic self-transmitting module 10 through the self-transmitting transmission line 9. The ultrasonic self-transmitting module 10 receives the ultrasonic-modulated light signal and transmits it back to the self-transmitting light source and demodulation module 8 through the self-transmitting transmission line 9; the self-transmitting light source and demodulation module 8 processes and analyzes the ultrasonic-modulated light signal.

[0037] Furthermore, the acoustic logging physical simulation system of this embodiment also includes a rotary stepping device (not shown in the accompanying drawings), which drives the ultrasonic self-transmitter module 10 to rotate synchronously around the central axis of the acoustic logging physical model 1. In this embodiment, the ultrasonic self-transmitter module 10 and the displacement stepping device are coaxially and centrally inserted into the through hole 11 of the acoustic logging physical model 1 using a fiber optic acoustic traction device (not shown in the accompanying drawings). The fiber optic acoustic traction device in this embodiment is a fixing device.

[0038] Specifically, such as Figure 8As shown, a rotating stepping device drives the ultrasonic self-transmitter module 10 inside the through-hole 11 to rotate. The self-transmitter light source and demodulation module 8 emit pulsed laser light, which is transmitted to the ultrasonic self-transmitter module 10 through the self-transmitter transmission line 9, generating ultrasonic waves through photo-induced ultrasound. These waves propagate inside the acoustic logging physical model 1. The self-transmitter light source and demodulation module 8 also emits sensing light, which is transmitted to the ultrasonic self-transmitter module 10 and then to the interior of the through-hole 11 through the self-transmitter transmission line 9. This sensing light is modulated by the ultrasonic waves inside the acoustic logging physical model 1 inside the through-hole 11, i.e., its characteristic parameters (such as intensity, phase, frequency, and polarization state) change under the influence of the ultrasonic waves. Subsequently, the ultrasonic self-transmitter module 10 receives the ultrasonically modulated light signal and transmits it back to the self-transmitter light source and demodulation module 8 through the self-transmitter transmission line 9. The self-transmitter light source and demodulation module 8 completes the acquisition, processing, and analysis of the light signal, achieving high signal-to-noise ratio demodulation. Based on information such as profile reflection amplitude and propagation time, a multi-dimensional image of the well perimeter is reconstructed, and the microstructural characteristics of the acoustic logging physical model are analyzed and evaluated.

[0039] In summary, this invention proposes a fiber optic ultrasonic-based acoustic logging physical simulation system. It innovatively applies fiber optic ultrasonic technology to acoustic logging physical simulation, constructing an optical ultrasonic experimental platform based on a high-similarity-scale factor model well, forming an elastic wave physical simulation with high precision, high reliability, and flexible controllability. Furthermore, it proposes a transmission-enhancing method for laser ultrasonic excitation and fiber optic ultrasonic detection, integrating a micro-probe-type ultrasonic exciter and fiber optic sensor within millimeter-level through-holes in the acoustic logging physical model, forming a microstructure fine detection technology with high signal-to-noise ratio, high sensitivity, and strong applicability. This invention significantly reduces the system complexity of acoustic logging physical simulation and effectively improves the wellbore acoustic field resolution, providing fundamental research support for acoustic logging field applications in areas such as logging response laws and evaluation methods. It also fully meets the needs of geophysical exploration, non-destructive testing, health monitoring, and other fields for the identification and detection of micro-morphological features in confined spaces.

[0040] This invention sets a high similarity scaling factor (not less than 50) to construct a small-scale acoustic logging physical simulation system (the volume of the acoustic logging physical model is <800 cm³). 3 With a through-hole diameter of <5mm, laser ultrasonic technology is introduced, combining a pulsed laser with an ultrasonic exciter (photoacoustic functional material). Optical enhanced ultrasonic technology that integrates fiber optic ultrasonics and fiber optic sensing is used to reconstruct the acoustic field characteristics within the acoustic logging physical model, effectively reducing the complexity of establishing the acoustic logging physical model system and improving the ability to resolve acoustic field characteristics within the through-hole.

[0041] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A physical simulation system for acoustic logging based on fiber optic ultrasound, characterized in that, The system includes a physical model for acoustic logging (1), a pulsed laser (2), a laser transmission line (3), an ultrasonic exciter (4), a fiber optic sensor (5), a signal transmission line (6), and a signal demodulator (7). The acoustic logging physical model (1) has a through hole (11) at its axial center, and the ultrasonic exciter (4) and the fiber optic sensor (5) are coaxially arranged inside the through hole (11). The pulsed laser (2) and the signal demodulator (7) are located outside the acoustic logging physical model (1). The pulsed laser (2) is connected to the ultrasonic exciter (4) through the laser transmission line (3). The pulsed laser (2) is used to emit pulsed laser and transmit it to the ultrasonic exciter (4) through the laser transmission line (3). The ultrasonic exciter (4) uses the pulsed laser to excite ultrasonic waves and emits the ultrasonic waves into the through hole (11). The signal demodulator (7) is connected to the fiber optic sensor (5) via the signal transmission line (6). The signal demodulator (7) is used to emit sensing light and transmit it through the signal transmission line (6) and the fiber optic sensor (5) to the interior of the through hole (11). The ultrasonically modulated optical signal is returned to the signal demodulator (7) via the fiber optic sensor (5) and the signal transmission line (6). The signal demodulator (7) is used to collect, process and analyze the received modulated optical signal.

2. The optical fiber ultrasonic-based acoustic logging physical simulation system according to claim 1, characterized in that, It also includes a displacement stepping device, which is used to drive the ultrasonic exciter (4) and the fiber optic sensor (5) to move synchronously along the central axis of the acoustic logging physical model (1).

3. The optical fiber ultrasonic-based acoustic logging physical simulation system according to claim 2, characterized in that, The ultrasonic exciter (4) and the fiber optic sensor (5) are respectively disposed at both ends inside the through hole (11) along the axial direction. The pulsed laser (2) is disposed outside the through hole (11) at one end of the ultrasonic exciter (4). The signal demodulator (7) is disposed outside the through hole (11) at one end of the fiber optic sensor (5).

4. The optical fiber ultrasonic-based acoustic logging physical simulation system according to claim 1, characterized in that, The number of ultrasonic exciters (4) is one or more. When the number of ultrasonic exciters (4) is multiple, the multiple ultrasonic exciters (4) are respectively connected to the pulse laser (2) through the laser transmission line (3). The multiple ultrasonic exciters (4) can excite ultrasonic waves sequentially or simultaneously.

5. The optical fiber ultrasonic-based acoustic logging physical simulation system according to claim 1, characterized in that, The number of optical fiber sensors (5) is one or more. When the number of optical fiber sensors (5) is multiple, the multiple optical fiber sensors (5) are respectively connected to the signal demodulator (7) through the signal transmission line (6). The multiple optical fiber sensors (5) can receive the ultrasonically modulated optical signal synchronously or in time-division manner.

6. The optical fiber ultrasonic-based acoustic logging physical simulation system according to claim 1, characterized in that, It also includes a rotary stepping device, which drives the ultrasonic exciter (4) and the fiber optic sensor (5) to rotate synchronously around the central axis of the acoustic logging physical model (1).

7. The optical fiber ultrasonic-based acoustic logging physical simulation system according to claim 6, characterized in that, The ultrasonic exciter (4) and the fiber optic sensor (5) are arranged in parallel on the central axis of the through hole (11), and the pulsed laser (2) and the signal demodulator (7) are arranged on the same side of the through hole (11).

8. A physical simulation system for acoustic logging based on fiber optic ultrasound, characterized in that, It includes a sonic logging physical model (1), a self-transmitting light source and demodulation module (8), a self-transmitting transmission line (9), and an ultrasonic self-transmitting module (10), among which, The acoustic logging physical model (1) has a through hole (11) in the center along the axial direction. The ultrasonic self-transmitter module (10) is located inside the through hole (11) and on the central axis of the through hole (11). The self-transmitter light source and demodulation module (8) is located outside the acoustic logging physical model (1). The self-transmitter light source and demodulation module (8) is connected to the ultrasonic self-transmitter module (10) through the self-transmitter transmission line (9). The ultrasonic self-transmitter module (10) can rotate around the central axis of the through hole (11) inside the through hole (11). The self-transmitting light source and demodulation module (8) is used to emit pulsed laser and transmit it to the ultrasonic self-transmitting module (10) through the self-transmitting transmission line (9). The ultrasonic self-transmitting module (10) uses pulsed laser to excite ultrasonic waves and propagate them inside the through hole (11). The self-transmitting light source and demodulation module (8) is also used to emit sensing light and transmit it to the ultrasonic self-transmitting module (10) via the self-transmitting transmission line (9). The ultrasonic self-transmitting module (10) receives the ultrasonic-modulated light signal and transmits it back to the self-transmitting light source and demodulation module (8) via the self-transmitting transmission line (9). The self-transmitting light source and demodulation module (8) processes and analyzes the ultrasonic-modulated light signal.

9. The optical fiber ultrasonic-based acoustic logging physical simulation system according to claim 8, characterized in that, It also includes a rotary stepping device, which drives the ultrasonic transceiver module (10) to rotate synchronously around the central axis of the acoustic logging physical model (1).

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