An in-well salt cavity photoacoustic integrated detection and analysis system and method

Abstract

The application provides a downhole salt cavity photoacoustic integrated detection and analysis system and method, and belongs to the technical field of underground space detection. The hardware data acquisition and control module is integrated in a downhole probe, and innovatively combines a laser detection module, an acoustic wave detection module, an inertial measurement module and a mechanical movement module driven by a rotating and swing arm motor, is coordinately controlled through a main control circuit board, and realizes long-distance reliable communication between the modules and underground in a combination mode of a serial port and a CAN bus. The application solves the problems of low detection precision, single data and poor modeling efficiency of the prior art in a high reflection and humid salt cavity environment, and realizes high-precision, all-around and intelligent three-dimensional detection and analysis of a downhole salt cavity.

Description

Technical Field

[0001] This invention relates to the field of underground space exploration technology, and in particular to an integrated acoustic, optical, and electronic detection and analysis system and method for underground salt cavities. Background Technology

[0002] Three-dimensional laser scanning technology has become a core method for exploring underground caverns or salt cavities. This technology acquires high-precision point cloud data through non-contact measurement, achieving millimeter-level topographic reconstruction. Combined with SLAM algorithms, mobile scanning equipment can improve operational efficiency. Sonar detection technology serves as a supplement, providing additional capabilities through... Rotational scanning is used to acquire profile data of the salt cavity.

[0003] However, existing technologies have significant drawbacks. First, the highly reflective surface of salt cavities easily leads to overexposure of laser signals and missing point cloud data, while dust and humidity interference further reduce scanning quality. Second, the equipment has poor mobility in confined salt cavities; traditional stationary scanning methods are inefficient, while mobile solutions face the problem of accumulated positioning errors. Furthermore, real-time data processing algorithms are immature, massive point cloud analysis is time-consuming, and manual identification is inefficient. In addition, the lack of standardized procedures for multi-sensor (such as laser and sonar) fusion results in uneven accuracy of the 3D model, affecting the reliability of salt cavity surrounding rock stability analysis. Although patents such as CN202410503375.3 disclose salt cavern safety monitoring systems, they mostly focus on risk assessment based on existing data rather than addressing the aforementioned technical bottlenecks in high-precision, integrated data acquisition and real-time modeling.

[0004] Therefore, there is an urgent need for an integrated detection system that can adapt to the harsh downhole environment, integrate multiple source sensors, and achieve high-precision data acquisition, fusion, and rapid 3D modeling and analysis. Summary of the Invention

[0005] This invention aims to solve at least one of the technical problems existing in the prior art, and proposes an integrated acoustic-optical-electric detection and analysis system and method for underground salt cavities. It addresses the technical challenges of three-dimensional morphological detection of underground caverns or underground salt cavities, such as the high reflectivity of the salt cavity surface and the ease with which point cloud data is lost.

[0006] In a first aspect, embodiments of the present invention provide an integrated acoustic-optical-electric detection and analysis system for downhole salt cavities, comprising:

[0007] The hardware data acquisition and control module is used to perform multimodal data acquisition downhole.

[0008] The software analysis, processing, and display module is used to process, model, and visualize the collected data;

[0009] The hardware data acquisition and control module is connected to the software analysis, processing, and display module via a communication link; wherein, the hardware data acquisition and control module is integrated into a downhole probe, the downhole probe comprising:

[0010] The laser detection module uses the indirect time-of-flight measurement method with a laser wavelength range of 600~1000nm to acquire laser point cloud data of the cavity, with a laser detection accuracy of millimeters.

[0011] The acoustic detection module includes a top ultrasonic sensor for short-range collision avoidance and a side acoustic ranging probe for cavity morphology measurement, with an acoustic detection accuracy of millimeters.

[0012] The inertial measurement module, with a built-in high-precision gyroscope, is used to acquire the probe's depth and tilt angle data, with an angle data error within one-thousandth.

[0013] The mechanical motion module includes a horizontal movement driven by a rotary motor. A rotating component and a vertical ± driven by a swing arm motor The swing arm component, wherein the laser detection module and the lateral acoustic ranging probe are mounted on the mechanical motion module;

[0014] The main control circuit board module, whose main control chip is FPGA or ARM, is used to coordinate and control the various modules and collect and analyze data in a timely manner.

[0015] The communication control module includes a serial communication unit for communication between modules inside the probe, and a CAN communication unit for long-distance data transmission with the ground, ensuring smooth and timely communication data and timely storage, exchange and transmission of data collected above and below ground.

[0016] The power supply module is used to provide power to the various modules inside the probe to ensure the division of labor and cooperation among the modules.

[0017] Preferably, the laser detection module adopts a laser ranging method that combines phase method and pulse method; the operating frequency of the side acoustic wave ranging probe is lower than the operating frequency of the top anti-touch acoustic wave sensor, wherein the operating frequency of the top acoustic wave sensor is about 1MHz and the detection distance is within 10 meters, and the operating frequency of the side acoustic wave sensor is about 250KHz and the detection distance is within 100 meters.

[0018] Preferably, in the mechanical motion module, the swing arm motor is an eccentric wheel swing arm motor, and the rotary motor is a high-precision geared motor;

[0019] Among them, the angle data of the swing arm motor M1(i, 0, k) and the rotary motor M2(i, j, 0) and the tilt data of the gyroscope T(i, j, k) together constitute the three-dimensional spatial physical coordinate system O(x,y, z) of the laser point data and the acoustic wave detection data, which is used to map the laser point cloud data and the acoustic wave data into this three-dimensional coordinate system;

[0020] The laser point data J(x, y, z) and acoustic data S(x, y, z) obtained by the laser probe and acoustic probe are used to construct a spatial three-dimensional laser point cloud dataset JJ(x, y, z) and a three-dimensional acoustic detection dataset SS(x, y, z) based on the three-dimensional spatial physical coordinate system O(x, y, z); where O(x, y, z)={ M1(i, 0, k) ∩M2(i, j, 0) ∩T(i, j, k)}.

[0021] Preferably, the main control circuit board module sends control commands to the mechanical motion module, laser detection module, acoustic wave detection module, and inertial measurement module and receives collected data through the serial communication unit; and transmits control signals and collected data bidirectionally to the software analysis, processing, and display module on the ground via the optoelectronic composite cable through the CAN communication unit.

[0022] The various modules inside the downhole probe communicate with each other via 485 / 232 / TTL serial ports and back up and save the laser point cloud data in real time. At the same time, after analysis and processing by the main control board chip, the data is transmitted to the ground over long distances via a composite cable through a CAN module.

[0023] Preferably, the software analysis, processing, and display module includes:

[0024] The data fusion unit is used to fuse laser point cloud data, acoustic wave data, probe angle data, and tilt angle data to generate a unified three-dimensional point cloud dataset.

[0025] The 3D modeling unit is used to process the fused 3D point cloud data based on the Poisson surface reconstruction algorithm or the voxel modeling method to construct the 3D model of the salt cavity.

[0026] The risk warning unit is used to assess and classify the risk of point cloud data in the 3D model based on preset comprehensive factors, and to provide visual warnings in the 3D model through color annotation.

[0027] Preferably, the data fusion unit performs the following steps:

[0028] As the probe is being lowered into the well in an orderly manner under the traction of the ground cable car's steel cable, the probe's front-facing acoustic probe and front-facing high-definition camera are activated to acquire ultrasonic data Ud and high-definition video data Pd. This data is used by ground observers to visually determine the probe's position in the well and the working conditions in front of the probe, in order to prevent the probe from colliding with the bottom or getting stuck in the hole.

[0029] After the well probe is lowered to the designated depth, the side-mounted laser detection module is activated in a waterless environment, and the three-dimensional morphological data of the cavity is collected under the drive of the rotary motor and the swing arm motor.

[0030] In the presence of water, the low-frequency ultrasonic probe is activated. Based on the probe angle data Ad and tilt angle data Td, the laser point cloud data Ld and the low-frequency acoustic wave data Sd are converted to a three-dimensional physical coordinate system. Then, normalization processing is performed. According to the distance correlation criterion, outliers are removed, and the average value of the two is inserted between two points with large distances to make the data structure symmetrical. Finally, the overall laser and acoustic wave point cloud data is smoothed to make the boundary of the three-dimensional model reconstructed from the detection data smoother.

[0031] Among them, the probe tilt angle data Td and the rotating arm data Ad are used together for probe positioning in spatial physical coordinates; the optical video data Pd is used to check the probe's forward movement status and troubleshoot faults in a timely manner; the ultrasonic data Ud is used to determine the probe's bottom contact status; the low-frequency acoustic wave data Sd is used to obtain the three-dimensional morphology of the salt cavern cavity in the underwater part; and the laser point cloud data Ld is used to obtain the three-dimensional morphology of the salt cavern cavity in the waterless part.

[0032] Preferably, the power supply module receives power transmitted from the ground via an optical-electric composite cable, and after voltage conversion, provides stable power supplies of different voltage levels required by each module in the probe; the main control chip of the main control circuit board module can be an FPGA Xilinx-XC7A100T or a Ziguang PLG50H.

[0033] Preferably, the software analysis, processing and display module is implemented based on the Qt platform and integrates the PCL and VTK libraries, supporting the visualization, interaction and rendering of 3D point clouds;

[0034] On the Qt platform, the PCL point data structure and VTK 3D loading and rendering technology are adopted. Within the Qt+PCL+VTK framework, the 3D display and morphological characteristics of cavity laser point cloud data are efficiently statistically analyzed, realizing the statistical analysis of cavity volume and the identification of irregular areas. By color-coding individual laser point cloud data points according to comprehensive factors, integrated labeling and risk warning of high, medium and low risk areas are realized.

[0035] The comprehensive factor is calculated as a weighted average of the local point cloud curvature value, the deviation value from the benchmark model, and the distance value of the boundary region of outliers.

[0036] Secondly, the present invention also provides an integrated acoustic-optical-electric detection and analysis method for downhole salt cavities, comprising:

[0037] The downhole probe is lowered to the predetermined position in the downhole salt cavity under the traction of the surface winch and load cable;

[0038] During the lowering of the probe, the top ultrasonic sensor and high-definition camera are activated to monitor for collision avoidance and observe the working conditions ahead.

[0039] After reaching the predetermined position, the laser detection module or the side acoustic ranging probe is activated according to the cavity environment. At the same time, the mechanical motion module is activated to make the laser detection module rotate horizontally and swing vertically to scan the perimeter of the cavity.

[0040] Real-time acquisition of laser point cloud data Ld, ultrasonic data Ud, low-frequency sound wave data Sd, probe angle data Ad, and tilt angle data Td, and local storage;

[0041] The collected data is transmitted to the software analysis, processing, and display module via CAN communication;

[0042] The software analysis, processing, and display module performs multi-source data fusion, 3D modeling, and risk warning analysis, and displays the results.

[0043] Preferably, in the three-dimensional modeling step, CUDA-based parallel computing technology is used to accelerate the processing of massive point cloud data; in the risk warning analysis, according to different target requirements, the comprehensive factor value of each point cloud data is calculated, and by setting a risk warning threshold, the regions in the three-dimensional model are divided into different risk levels and marked with different colors according to the comprehensive factor values ​​of the point cloud data. Attached Figure Description

[0044] Figure 1 A schematic diagram of the overall architecture for integrated acoustic-optical-electric detection and analysis of downhole salt cavities provided in an embodiment of the present invention;

[0045] Figure 2 This is a schematic diagram of the control signal and data transmission flow provided in an embodiment of the present invention;

[0046] Figure 3 This is a schematic diagram of the power supply signal flow provided in an embodiment of the present invention;

[0047] Figure 4 This is a schematic diagram of the power supply principle of the main control circuit board provided in an embodiment of the present invention;

[0048] Figure 5 This is a schematic diagram of a USB to 5V power supply provided in an embodiment of the present invention;

[0049] Figure 6 A schematic diagram of the kernel power supply and RAM power supply provided in an embodiment of the present invention;

[0050] Figure 7 A schematic diagram of the auxiliary power supply provided in an embodiment of the present invention;

[0051] Figure 8 This is a schematic diagram of the upper part of an integrated acoustic-optical-electric detection and analysis system for downhole salt cavities, provided in an embodiment of the present invention.

[0052] Figure 9 This is a schematic diagram of the lower half of a downhole salt cavity acoustic-optical-electric integrated detection and analysis system provided in an embodiment of the present invention.

[0053] Explanation of reference numerals in the attached drawings: 1-Sealing seat; 2-Outer sleeve; 3-Aviation plug socket; 4-Aviation plug; 5-Upper tube; 6-Rotary motor; 7-Middle tube; 8-Rotary electric shaft; 9-Bearing seat; 10-Shaft sleeve; 11-Nut; 12-Lower tube; 13-Oscillating motor; 14-Oscillating motor mounting plate; 15-Hanging gear set; 16-Angle gearbox cover; 17-Angle gearbox; 18-Oscillating tube; 19-First ranging sensor; 20-Second ranging sensor; 21-Large ultrasonic sensor; 22-Small ultrasonic sensor. Detailed Implementation

[0054] To enable those skilled in the art to better understand the technical solutions of the present invention, exemplary embodiments of the present invention are described below in conjunction with the accompanying drawings, including various details of the embodiments of the present invention to aid understanding. These should be considered merely exemplary. Therefore, those skilled in the art should recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the present invention. Similarly, for clarity and brevity, descriptions of well-known functions and structures are omitted in the following description.

[0055] Where there is no conflict, the various embodiments of the present invention and the features thereof may be combined with each other.

[0056] As used herein, the term “and / or” includes any and all combinations of one or more related enumerated entries.

[0057] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used herein, the singular forms “a” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that when the terms “comprising” and / or “made of” are used in this specification, the presence of the stated feature, integral, step, operation, element, and / or component is specified, but the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or groups thereof is not excluded. Terms such as “connected” or “linked” are not limited to physical or mechanical connections but can include electrical connections, whether direct or indirect.

[0058] Unless otherwise specified, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art. It will also be understood that terms such as those defined in commonly used dictionaries should be interpreted as having the meaning consistent with their meaning in the context of the relevant art and the invention, and will not be interpreted as having an idealized or overly formal meaning unless expressly so defined herein.

[0059] In the technical solution of this invention, the collection, storage, use, processing, transmission, provision, and disclosure of user personal information all comply with relevant laws and regulations and do not violate public order and good morals. The use of user data in this technical solution follows relevant national laws and regulations (e.g., the "Information Security Technology - Personal Information Security Specification"). For example: appropriate measures are taken for personal information access control; restrictions are imposed on the display of personal information; the purpose of using personal information does not exceed the scope of direct or reasonable association; and explicit identity targeting is eliminated when using personal information to avoid precisely locating a specific individual.

[0060] A search revealed five similar patents in the relevant field, as follows:

[0061] CN202510451917.1, CN202410503375.3, CN202510731430.9, CN202111405846.X, CN202510452771.2, CN202210800194.8. From the above-mentioned existing publicly available technologies, it can be seen that the current technical difficulties and bottlenecks are mainly manifested in environmental adaptability and data processing complexity. The highly reflective surface of the salt cavity easily leads to overexposure of the laser signal and missing point cloud data, while dust and humidity interference further reduce the scanning quality. The mobility of the equipment in the confined salt cavity is limited; traditional stationary scanning is inefficient, while mobile solutions face the problem of accumulated positioning errors. Real-time data processing algorithms are not yet mature; massive point cloud analysis is time-consuming, and manual identification of structural surfaces is inefficient; semi-automatic methods lack robustness in feature-sparse scenarios. Multi-sensor fusion suffers from high hardware costs and difficulties in synchronous calibration. While explosion-proof designs improve safety, their size and power consumption limit portability and hinder stable application in harsh downhole conditions, making them unsuitable for high-temperature and high-humidity environments. Furthermore, the lack of standardized procedures for sonar and laser data fusion leads to uneven accuracy in 3D models, affecting the reliability of stability analysis of surrounding rock in salt cavities.

[0062] To address at least one of the technical problems existing in the aforementioned related technologies, the present invention provides an integrated acoustic-optical-electric detection and analysis system for downhole salt cavities, such as... Figure 1 As shown, it includes a hardware data acquisition and control module, a software analysis, processing and display module, and a communication link connecting the two.

[0063] I. The hardware data acquisition and control module is integrated into a single downhole probe, and its core modules include:

[0064] (1) Laser detection module: The indirect time-of-flight measurement method is adopted, preferably a combination of phase method and pulse method. The laser wavelength range is 600~1000nm to achieve millimeter-level or even higher ranging accuracy, while taking into account the sampling rate.

[0065] To investigate the spectral absorption characteristics of lasers of different wavelengths in different media and the propagation laws under different gas pressures, temperatures, humidity and wall conditions, this study aims to determine the optimal laser band and the optimal light source power, and to establish a laser control optimization method suitable for various water and gas impurity environments.

[0066] Currently, the optical time-of-flight measurement methods used in laser ranging mainly include: direct time-of-flight (dToF) and indirect time-of-flight (iToF).

[0067] Direct Time-of-Flight (dToF) measurement involves directly measuring the time difference between the emitted and received laser beams and calculating the distance traveled by the laser beam based on the speed of light. Because of the speed of light, this method requires extremely high response speeds in the circuitry related to the time-of-flight measurement to improve the resolution of the measurement, thereby increasing the final distance resolution. Given the current technological level of the devices, its distance resolution can reach the centimeter level.

[0068] Indirect time-of-flight (iToF) measurement typically refers to a method that modulates the emitted laser and analyzes the changes in its characteristics after propagating a certain distance, thereby indirectly measuring the time of flight of light. This method is most commonly used to analyze changes in the phase characteristics of the modulated laser.

[0069] Compared to direct time-of-flight (dToF), indirect time-of-flight (iToF) significantly reduces the hardware processing speed requirements, is easier to implement, and offers higher distance resolution, currently reaching millimeter or even micrometer levels. However, due to the need for modulation information analysis of the laser, iToF's measurement speed is much lower than dToF.

[0070] This invention employs the indirect time-of-flight (iToF) method, more specifically, a phase-difference laser ranging method. This method is typically suitable for short- to medium-range ranging, achieving measurement accuracy down to the millimeter or even micrometer level. The basic principle of phase-difference laser ranging is to modulate the emitted laser at a specified frequency, then illuminate the object being measured, and finally reflect the light back to the receiver. The emitted modulated laser and the received modulated laser carry different phase information. By analyzing the phase at the time of emission and reception, and calculating the phase difference, the actual propagation distance of the laser can be calculated by combining this phase difference information with the specified modulation frequency.

[0071] The optimal laser wavelength selected for this system is 600-1000 nm. A laser ranging method combining phase-based (610-690 nm) and pulse-based (905 nm) approaches is employed, ensuring both high measurement accuracy and a high sampling rate. The selection of the laser source wavelength primarily considers the characteristics of the salt cavity environment. Research indicates that factors such as humidity, material reflectivity, and detection distance within the salt cavity environment directly influence the choice of laser wavelength. In high-humidity salt cavity environments, longer wavelength lasers (e.g., 1550 nm) exhibit better penetration, effectively reducing the absorption and scattering of the laser signal by water vapor. Furthermore, the reflectivity of salt rock materials varies significantly for specific wavelengths; selecting an appropriate wavelength can improve the quality of point cloud data.

[0072] (2) Acoustic wave detection module: including a high-frequency (e.g., 1MHz) top anti-touch acoustic wave sensor and a low-frequency side acoustic wave ranging probe, which are used for short-distance anti-collision and cavity morphology measurement in water environment, respectively.

[0073] An ultrasonic transducer is a device that converts signals from other energy sources into desired ultrasonic waves, signals, or energy. Conversely, it can convert ultrasonic signals or energy into another form of signal or energy. There are various types of ultrasonic transducers, such as electroacoustic transducers (including piezoelectric transducers, magnetostrictive transducers, electrodynamic and electromagnetic transducers), and fluid dynamic transducers (including airflow-excited cavity whistles, vortex whistles, rotary whistles, disc whistles, and fluid jet-excited reed whistles, etc.).

[0074] The system employs two ultrasonic sensors: a top-mounted anti-touch acoustic sensor and a side-mounted acoustic ranging probe. The top-mounted anti-touch acoustic sensor uses a high ultrasonic frequency of 1MHz and is mainly used to detect the distance in front of the probe when it is lowered into the well, addressing short-distance ranging issues such as preventing contact, collisions, and bottom contact. The side-mounted acoustic ranging probe is used for three-dimensional morphological measurement of the cavity in a water-containing environment, and also for comparative testing data with the laser probe's detection data.

[0075] (3) Motor rotation + swing arm control module, i.e. mechanical motion module: This is the key to realizing three-dimensional scanning, including the horizontal movement driven by a high-precision geared motor. Rotating components and vertical ± driven by eccentric wheel swing arm motor Swing arm assembly. Laser and side acoustic wave probes are mounted on this module. Motor selection criteria: Motor selection must comprehensively consider torque requirements, control accuracy, and environmental adaptability. Studies have shown that load torque has a significant impact on the current control accuracy of DC motors. In multi-motor drive systems of mining belt conveyors, direct torque control methods can reduce electromagnetic torque pulsation.

[0076] Motion Control System: The positioning accuracy and speed stability of the downhole probe directly affect system performance. A fuzzy PID control system optimized based on a genetic algorithm exhibits excellent response speed and stability in downhole cutting tools, with a steady-state error of less than 5%. For brushless DC motor drive systems, an improved harmonic injection active disturbance rejection control method can effectively suppress torque pulsation in rotating components. The scanning and swing arm components adjust the detection angle. The design must consider the confined space downhole and mechanical stability. The rotating components are driven by stepper motors, and the swing arm components use servo motors to ensure high-precision positioning.

[0077] This system selects an eccentric wheel swing arm motor to achieve the vertical ± The swing arm control uses a high-precision geared motor to rotate the bottom probe component, achieving horizontal positioning. Rotation control.

[0078] (4) Inertial measurement module: Built-in high-precision gyroscope for real-time sensing of the probe’s tilt state and depth.

[0079] A built-in high-precision gyroscope is used to achieve depth positioning and probe tilting of the downhole probe. The three main modules are all based on UART control, an asynchronous serial communication protocol. The core functionality involves bidirectional data transmission via two signal lines (TX for transmitting and RX for receiving), eliminating the need for a clock synchronization signal. Data frame structure: Each frame contains a start bit (1 low-level bit), data bits (5-9 bits, commonly 8 bits), a parity bit (optional, odd / even / no parity), and a stop bit (1-2 high-level bits). Baud rate synchronization: Both communicating parties must agree on the same baud rate (e.g., 9600, 115200bps) to ensure consistent sampling timing. Asynchronous transmission: Relying on the start bit to trigger sampling at the receiving end, no additional clock line is required, resulting in a simple hardware structure. Transmitter: Converts parallel data into serial signals according to the frame structure, sequentially sending the start bit, data bits, parity bit, and stop bit. Receiver: After detecting the start bit, samples subsequent signals at timed intervals according to the baud rate, reconstructs parallel data, and performs verification. Verification mechanism: The parity bit determines whether data transmission has errors; without parity, only the stop bit confirms the end of the frame. In summary, the hardware requirements are simple (only two wires, TX and RX), the cost is low, and the adaptation distance is moderate (short-distance communication).

[0080] The motor interface is based on RS-485 communication control. To ensure software simplicity and reliability, a UART-to-RS-485 circuit was designed, therefore the circuit board only needs to have a reserved UART communication interface. The motor is controlled according to bus parameters and protocol commands. The laser controller interface is controlled by a 72-bit UART protocol. The gyroscope interface is controlled by a 22-byte UART protocol.

[0081] Main control circuit board module: Based on FPGA (such as Xilinx-XC7A100T) or ARM, it is responsible for signal scheduling, data processing and system control.

[0082] (5) Communication control module: The probe uses serial communication such as 485 / 232 / TTL; it uses the CAN communication protocol with strong anti-interference capability to communicate with the ground, and transmits and controls data over long distances (more than 1 kilometer) through an optical fiber composite cable.

[0083] The system employs 485 / 232 / TTL serial communication between its modules to achieve communication control and signal modulation. For laser point cloud data and acoustic data acquired by the laser and acoustic probes, long-distance data transmission and information exchange control of above-ground and underground detection data and control signals are achieved through a CAN communication module and twisted-pair cables.

[0084] CAN (Controller Area Network) is a multi-master, differential serial communication protocol. Its core uses two differential signal lines (CAN_H and CAN_L) to achieve highly interference-resistant, long-distance multi-node data transmission without requiring master coordination. Bus Structure: It adopts a differential bus design. During normal communication, the voltage difference between CAN_H and CAN_L is approximately 2V (dominant level, logic 0), and when idle, the voltage difference is 0V (recessive level, logic 1). Frame Structure: A standard frame contains an 11-bit identifier (ID), and an extended frame contains a 29-bit ID. The core consists of a start bit, arbitration field (ID), control field, data field (bytes 0-8), CRC check field, acknowledge field, and end-of-frame bit. Arbitration Mechanism: It uses wired-AND logic. The smaller the ID value, the higher the priority. During transmission, the bus level is compared with the node's own transmission level to determine if a conflict has occurred. Nodes with lower priority automatically withdraw from transmission. Transmission Process: Nodes package data into CAN frames, start transmission after detecting bus idleness, compete for bus access through the arbitration field, and release the bus after transmission is complete. Reception Process: All nodes listen to the bus and only receive frames that match their filtering criteria (ID matches). Data integrity is verified using CRC checksum; if the reception is correct, an acknowledgment signal is sent. Error Handling: Includes various error types such as bit errors and CRC errors. Upon detecting an error, an error frame is sent to notify other nodes. In case of a serious error, the node will enter a bus shutdown state. In summary, it has strong anti-interference capabilities (differential transmission), supports multiple nodes (up to 110), has a long transmission distance (up to 10km at low speeds), and possesses a fault isolation mechanism.

[0085] Precautions:

[0086] Before powering on, you need to select the mode; before powering on, you need to select the power supply. Here, we select 3.3V.

[0087] (6) Main control circuit board module: The main control circuit board module includes the main control chip (ARM / FPGA, etc.) and its auxiliary functional circuit driver modules, such as the CAN communication module, the acoustic wave transmitting and receiving circuit driver module, the 485 / 232 / TTL serial communication module port, and the ports for controlling the swing arm motor and the rotary motor. The main function of this module is to realize the exchange of control signals and the transmission of detection data between the ground software system and the underground hardware system.

[0088] refer to Figure 2As shown, the host computer software (ground) sends control signals and uses a long-distance CAN communication module to achieve long-distance (over 1 kilometer) control signal transmission and detection data acquisition. Current, voltage, control signals, and detection data are all transmitted within the optical fiber composite cable, which consists of positive and negative power lines, twisted-pair communication lines, steel wire ropes, and a tensile-resistant outer shell.

[0089] Under normal power module conditions, the main control circuit board contains the main control chip and various modules and their communication ports, including CAN communication. The main control chip serves as the control and command center for the entire underground probe. It receives control signals from the ground via the CAN communication port and transmits probe data back to the ground. The main control chip issues commands via the 485 / 232 / TTL serial communication port to control the probe's swing arm angle (using the swing arm motor) and rotation angle (using the rotary motor). It also issues commands via the 485 / 232 / TTL serial communication port to acquire laser point data from the laser probe and to acquire acoustic data from the acoustic probe and receive tilt data from the gyroscope in real time. The angle data of the swing arm motor M1(i, 0, k) and the rotary motor M2(i, j, 0), and the tilt data T(i, j, k) of the gyroscope together constitute the three-dimensional spatial physical coordinate system O(x, y, z) of the laser point data and the acoustic wave detection data. The laser point data J(x, y, z) and acoustic wave data S(x, y, z) obtained by the laser probe and the acoustic wave probe can be used to construct a spatial stereo laser point cloud dataset JJ(x, y, z) and a three-dimensional acoustic wave detection dataset SS(x, y, z) based on the three-dimensional spatial physical coordinate system O(x, y, z). Wherein, O(x, y, z) = { M1(i, 0, k) ∩ M2(i, j, 0) ∩ T(i, j, k)}.

[0090] A better solution uses the FPGA Artix-7 XC7A35T 100T as the main control chip, with domestically produced Ziguang PLG50H and XC7Z045 chips handling data acquisition and control respectively. The main control circuit board is based on the Xilinx-XC7A100T chip, employing a 28nm low-power process, a core voltage of 1.0V, typical dynamic power consumption of approximately 1.5W, and static power consumption below 0.5W. It supports an industrial-grade temperature range (-40℃ to 100℃) and possesses sufficient logic, storage, digital signal processing, and I / O interfaces to ensure the driving, data reception, and transmission of multiple sensors. This cavity detection circuit board includes a USB-to-serial port and 5V power supply, a flash module, an FPGA voltage power supply, DDR3, a CAN communication module, a motor control interface, a gyroscope data interface, a laser sensor command interface, and custom user I / O ports.

[0091] (7) Main power supply – power supply module. For example... Figure 3 As shown, in actual operation, a 220V AC mains power or 380V AC power input is required from the ground, which is then regulated by a ground voltage regulator. Voltage and current control is used to ensure the probe input voltage is within a reasonable range. This is based on the impedance of the customized optoelectronic composite cable. Distance of probe downhole detection Calculate the voltage drop of wires and cables. Ensure the main control power supply of the underground probe The voltage is in the range of 24~36V, and the current is... Within the specified range. The calculation formula is as follows, where the wire impedance is typically 1.2 ohms / km. .

[0092] After obtaining stable voltage and current from the ground, the main control power supply is primarily responsible for providing a stable 24V voltage and 5A current to the swing arm motor and rotary motor, and a 26V rated voltage to the acoustic probe. It also provides a stable 5V rated voltage and 1A rated current to the main control circuit board. In the event of an unexpected power outage or other abnormal situation on the ground, the emergency battery inside the underground probe will supply power to the main control power supply.

[0093] The main control circuit board has many I / O input / output ports, some of which are specifically responsible for providing 3.3V voltage and rated current to the laser probe, 3.3V voltage and rated current to the 484 / 232 / TTL serial communication module, 3.3V rated voltage and current to the gyroscope, and 3.3V voltage and current to the built-in parameter module. This main control circuit board communicates and controls with the ground CAN module.

[0094] Among them, the power supply of the main control circuit board is as follows Figures 4 to 7 As shown, for the 35V-25V and 35V-5V power supply designs, two TPS5430 power chips are used. The input capacitor, output capacitor, switching diode, inductor, and the model and parameters of the switching capacitor were strictly selected. Following layout rules, the output DC power supply ripple for both channels was ensured to be less than 20mV. The Xilinx-XC7A100T chip's power supply has a strict timing sequence: VCCINT (core voltage), VCCRAM (RAM voltage), VCCAUX (auxiliary voltage), and VCCO (IO voltage). The total voltage of the circuit board is 5V, accessible via a USB interface or directly from the 5V power pin.

[0095] II. The software analysis, processing, and display module is deployed on a ground computer, and its core functions include:

[0096] Data fusion: The laser point cloud data (Ld), acoustic wave data (Sd / Ud), probe angle data (Ad), and tilt angle data (Td) are unified into a three-dimensional physical coordinate system O(x, y, z), and then denoised, interpolated, and smoothed.

[0097] 3D modeling: Using algorithms such as Poisson surface reconstruction and voxel modeling, discrete point clouds are transformed into continuous and smooth 3D cavity models.

[0098] Risk Warning and Visualization: Developed on the Qt platform based on the PCL and VTK libraries, this feature enables the visualization and rendering of 3D models. It conducts risk assessments based on comprehensive factors (such as point cloud curvature, deviation from the baseline model, and distance to outlier boundary regions), and visually identifies areas with different risk levels using color mapping. The comprehensive factor value is determined by weighted averaging of several indicators, including point cloud curvature, deviation from the baseline model, and distance to outlier boundary regions, based on the calculation objective, ultimately yielding the comprehensive factor value for each point cloud data point.

[0099] like Figure 1 As shown, the entire system consists of a downhole probe (hardware system) and a ground workstation (software system). The downhole probe is connected to the ground via a fiber optic composite cable that includes power and communication lines.

[0100] The probe housing features an explosion-proof and corrosion-resistant design. Internally, the main control FPGA board (XC7A100T) is the core of the control system. It controls the swing arm motor and rotary motor via a UART-to-485 converter to precisely adjust the detection angle. Simultaneously, it controls the laser controller and reads gyroscope data via a specific UART protocol. Raw data acquired by the laser module (610-690nm and 905nm bands) and the acoustic module (1MHz at the top, low frequency at the side) are initially processed and buffered by the FPGA.

[0101] For power supply, a 220V / 380V power supply is provided from the ground, which is regulated and then transmitted to the probe via a fiber optic composite cable. The probe's internal power management module uses chips such as the TPS5430 to convert the input voltage (24-36V) into various voltages required by the FPGA (such as a 1.0V core voltage and a 3.3V external I / O voltage), as well as the 24V voltage required by the motor and the 26V voltage required by the acoustic probe. The FPGA's power-on sequence is strictly followed.

[0102] For data transmission, serial communication is used between modules within the probe. Processed sensor data, angle data, and attitude data are packaged by the FPGA and transmitted to the ground via a CAN transceiver (e.g., in SPI mode) through the CAN bus and twisted-pair cable in the optical fiber composite cable. The ground CAN receiving module then sends the data to the industrial control computer.

[0103] The ground software system (developed based on Qt, PCL, and VTK) receives data. The software first performs data parsing and fusion. Based on the received Ad and Td data, it transforms the Ld and Sd data from polar coordinates to a unified Cartesian coordinate system O(x, y, z). Subsequently, it performs data cleaning (such as denoising using the RANSAC algorithm) and intelligent interpolation.

[0104] The cleaned point cloud is then fed into the 3D modeling module. The mathematical basis of Poisson reconstruction is solving the following Poisson equation: in Let be the implicit function to be determined, and v be the point cloud normal vector field. This is achieved by minimizing the energy functional. An approximate solution to the equation can be obtained. Compared to traditional Alpha Shapes or BallPivoting algorithms, Poisson reconstruction can generate smoother and more complete surface models, and it is particularly adept at handling point cloud data containing noise and uneven density. To handle massive amounts of data, CUDA can be used for parallel acceleration.

[0105] Finally, the system loads the 3D model in the visualization interface. Users can browse it interactively. The risk warning module calculates the comprehensive risk factor for each grid cell or point cloud region (for example, excessive local curvature may indicate stress concentration). Based on preset thresholds, the system classifies risks into high, medium, and low levels and renders them on the 3D model using colors such as red, yellow, and green, thus achieving intuitive risk warnings.

[0106] like Figure 8 and Figure 9 As shown, this device is composed of a sealing seat 1, an outer sleeve 2, an aviation plug socket 3, an aviation plug 4, an upper tube 5, a rotary motor 6, a middle tube 7, a rotary electric shaft 8, a bearing seat 9, a bushing 10, a nut 11, a lower tube 12, a swing motor 13, a swing motor mounting plate 14, a rotating gear set 15, an angle gear box cover 16, an angle gear box 17, a swing tube 18, a first ranging sensor 19, a second ranging sensor 20, a large ultrasonic sensor 21, and a small ultrasonic sensor 22, all sealed together.

[0107] This embodiment aims to achieve the following objective: to measure the distance to spatial objects using the distance-measuring capabilities of a laser sensor. It also utilizes a large ultrasonic sensor 21 and a small ultrasonic sensor 22 to perform an object retraction test, and includes a first distance-measuring sensor 19 and a second distance-measuring sensor 20 distributed on the outer surface of the outer casing 2, which measure the distance as the body moves horizontally. The four sensors can rotate and measure distances horizontally in a 360-degree direction. Furthermore, they can move vertically up and down, scanning and measuring distances in the vertical direction, and then using software to create a map based on the measurement data.

[0108] Secondly, the present invention also provides an integrated acoustic-optical-electric detection and analysis method for downhole salt cavities, comprising:

[0109] Control the downhole probe to be lowered to the predetermined position in the downhole salt cavity;

[0110] During the lowering of the probe, the top ultrasonic sensor and high-definition camera are activated to monitor for collision avoidance and observe the working conditions ahead.

[0111] After reaching the predetermined position, the laser detection module or the side acoustic ranging probe is activated according to the cavity environment. At the same time, the mechanical motion module is activated to make the laser detection module rotate horizontally and swing vertically to scan the perimeter of the cavity.

[0112] Real-time acquisition of laser point cloud data Ld, ultrasonic data Ud, low-frequency sound wave data Sd, probe angle data Ad, and tilt angle data Td;

[0113] The collected data is transmitted to the software analysis, processing, and display module via CAN communication;

[0114] The software analysis, processing, and display module performs multi-source data fusion, 3D modeling, and risk warning analysis, and displays the results.

[0115] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0116] High precision and high integration: By combining phase-based laser with precision mechanical structure, millimeter-level detection accuracy is achieved; multiple sensors, including acoustic, optical and electrical sensors, are integrated into a single probe, resulting in a compact structure.

[0117] Enhanced environmental adaptability: By employing multi-band lasers and acoustic probes of different frequencies, it effectively copes with complex environments such as high reflectivity in salt cavities, and the presence or absence of water, thus overcoming the limitations of a single sensor.

[0118] Data fusion and intelligence: It realizes the automatic fusion and coordinate unification of multi-source heterogeneous data, and uses advanced algorithms for 3D reconstruction and intelligent risk analysis, which greatly improves data processing efficiency and the reliability of results.

[0119] High efficiency and reliability: The CAN bus ensures the stability of long-distance data transmission; the mechanical scanning mechanism enables all-round detection without blind spots; the system provides a powerful tool for salt cavity stability assessment, volume calculation and safety early warning.

[0120] Example embodiments have been disclosed herein, and while specific terminology has been used, it is for illustrative purposes only and should be construed as such, and is not intended to be limiting. In some instances, it will be apparent to those skilled in the art that features, characteristics, and / or elements described in conjunction with particular embodiments may be used alone, or in combination with features, characteristics, and / or elements described in conjunction with other embodiments, unless otherwise expressly indicated. Therefore, those skilled in the art will understand that various changes in form and detail may be made without departing from the scope of the invention as set forth in the appended claims.

Claims

1. A downhole salt cavity acoustic-optical-electric integrated detection and analysis system, characterized in that, include: The hardware data acquisition and control module is used to perform multimodal data acquisition downhole. The software analysis, processing, and display module is used to process, model, and visualize the collected data; The hardware data acquisition and control module is connected to the software analysis, processing, and display module via a communication link; wherein, the hardware data acquisition and control module is integrated into a downhole probe, the downhole probe comprising: The laser detection module uses the indirect time-of-flight measurement method with a laser wavelength range of 600~1000nm to acquire laser point cloud data of the cavity, with a laser detection accuracy of millimeters. The acoustic detection module includes a top ultrasonic sensor for short-range collision avoidance and a side acoustic ranging probe for cavity morphology measurement, with an acoustic detection accuracy of millimeters. The inertial measurement module, with a built-in high-precision gyroscope, is used to acquire the probe's depth and tilt angle data, with an angle data error within one-thousandth. The mechanical motion module includes a horizontal movement driven by a rotary motor. A rotating component and a vertical ± driven by a swing arm motor The swing arm component, wherein the laser detection module and the lateral acoustic ranging probe are mounted on the mechanical motion module; The main control circuit board module, whose main control chip is FPGA or ARM, is used to coordinate and control the various modules and collect and analyze data in a timely manner. The communication control module includes a serial communication unit for communication between modules inside the probe, and a CAN communication unit for long-distance data transmission with the ground, ensuring smooth and timely communication data and timely storage, exchange and transmission of data collected above and below ground. The power supply module is used to provide power to the various modules within the probe to ensure the division of labor and cooperation among them.

2. The system according to claim 1, characterized in that, The laser detection module adopts a laser ranging method that combines phase method and pulse method; the operating frequency of the side acoustic wave ranging probe is lower than the operating frequency of the top anti-touch acoustic wave sensor. The top acoustic wave sensor operates at a frequency of about 1MHz and has a detection distance of less than 10 meters, while the side acoustic wave sensor operates at a frequency of about 250KHz and has a detection distance of less than 100 meters.

3. The system according to claim 1, characterized in that, In the mechanical motion module, the swing arm motor is an eccentric wheel swing arm motor, and the rotary motor is a high-precision geared motor; Among them, the angle data of the swing arm motor M1(i, 0, k) and the rotary motor M2(i, j, 0) and the tilt data of the gyroscope T(i, j, k) together constitute the three-dimensional spatial physical coordinate system O(x, y, z) of the laser point data and the acoustic wave detection data, which is used to map the laser point cloud data and the acoustic wave data into this three-dimensional coordinate system; The laser point data J(x, y, z) and acoustic data S(x, y, z) obtained by the laser probe and acoustic probe are used to construct a spatial three-dimensional laser point cloud dataset JJ(x, y, z) and a three-dimensional acoustic detection dataset SS(x, y, z) based on the three-dimensional spatial physical coordinate system O(x, y, z); where O(x, y, z)={ M1(i, 0, k) ∩M2(i, j, 0) ∩T(i, j, k)}.

4. The system according to claim 1, characterized in that, The main control circuit board module sends control commands to the mechanical motion module, laser detection module, acoustic wave detection module, and inertial measurement module and receives collected data through the serial communication unit; and transmits control signals and collected data bidirectionally to the ground software analysis, processing, and display module via the optoelectronic composite cable through the CAN communication unit. The various modules inside the downhole probe communicate with each other via 485 / 232 / TTL serial ports and back up and save the laser point cloud data in real time. At the same time, after analysis and processing by the main control board chip, the data is transmitted to the ground over long distances via a composite cable through a CAN module.

5. The system according to claim 4, characterized in that, The software analysis, processing, and display module includes: The data fusion unit is used to fuse laser point cloud data, acoustic wave data, probe angle data, and tilt angle data to generate a unified three-dimensional point cloud dataset. The 3D modeling unit is used to process the fused 3D point cloud data based on the Poisson surface reconstruction algorithm or the voxel modeling method to construct the 3D model of the salt cavity. The risk warning unit is used to assess and classify the risk of point cloud data in the 3D model based on preset comprehensive factors, and to provide visual warnings in the 3D model through color annotation.

6. The system according to claim 5, characterized in that, The data fusion unit performs the following steps: As the probe is being lowered into the well in an orderly manner under the traction of the ground cable car's steel cable, the probe's front-facing acoustic probe and front-facing high-definition camera are activated to acquire ultrasonic data Ud and high-definition video data Pd. This data is used by ground observers to visually determine the probe's position in the well and the working conditions in front of the probe, in order to prevent the probe from colliding with the bottom or getting stuck. After the well probe is lowered to the designated depth, the side-mounted laser detection module is activated in a waterless environment, and the three-dimensional morphological data of the cavity is collected under the drive of the rotary motor and the swing arm motor. In the presence of water, the low-frequency ultrasonic probe is activated. Based on the probe angle data Ad and tilt angle data Td, the laser point cloud data Ld and the low-frequency acoustic wave data Sd are converted to a three-dimensional physical coordinate system. Then, normalization processing is performed. According to the distance correlation criterion, outliers are removed, and the average value of the two is inserted between two points with large distances to make the data structure symmetrical. Finally, the overall laser and acoustic wave point cloud data is smoothed to make the boundary of the three-dimensional model reconstructed from the detection data smoother. Among them, the probe tilt angle data Td and the rotating arm data Ad are used together for probe positioning in spatial physical coordinates; the optical video data Pd is used to check the probe's forward movement status and troubleshoot faults in a timely manner; the ultrasonic data Ud is used to determine the probe's bottom contact status; the low-frequency acoustic wave data Sd is used to obtain the three-dimensional morphology of the salt cavern cavity in the underwater part; and the laser point cloud data Ld is used to obtain the three-dimensional morphology of the salt cavern cavity in the waterless part.

7. The system according to claim 1, characterized in that, The power supply module receives power transmitted from the ground through the optical fiber composite cable, and after voltage conversion, provides stable power supplies of different voltage levels to each module in the probe; the main control chip of the main control circuit board module is an FPGA Xilinx-XC7A100T or a Ziguang PLG50H.

8. The system according to claim 1, characterized in that, The software analysis, processing and display module is implemented based on the Qt platform and integrates the PCL and VTK libraries, supporting the visualization, interaction and rendering of 3D point clouds; On the Qt platform, the PCL point data structure and VTK 3D loading and rendering technology are adopted. Within the Qt+PCL+VTK framework, the 3D display and morphological characteristics of cavity laser point cloud data are efficiently statistically analyzed, realizing the statistical analysis of cavity volume and the identification of irregular areas. By color-coding individual laser point cloud data points according to comprehensive factors, integrated labeling and risk warning of high, medium and low risk areas are realized. The comprehensive factor is calculated as a weighted average of the local point cloud curvature value, the deviation value from the benchmark model, and the distance value of the boundary region of outliers.

9. A method for integrated acoustic-optical-electric detection and analysis of downhole salt cavities, characterized in that, include: The downhole probe is lowered to the predetermined position in the downhole salt cavity under the traction of the surface winch and load cable; During the lowering of the probe, the top ultrasonic sensor and high-definition camera are activated to monitor for collision avoidance and observe the working conditions ahead. After reaching the predetermined position, the laser detection module or the side acoustic ranging probe is activated according to the cavity environment. At the same time, the mechanical motion module is activated to make the laser detection module rotate horizontally and swing vertically to scan the perimeter of the cavity. Real-time acquisition of laser point cloud data Ld, ultrasonic data Ud, low-frequency sound wave data Sd, probe angle data Ad, and tilt angle data Td, and local storage; The collected data is transmitted to the software analysis, processing, and display module via CAN communication; The software analysis, processing, and display module performs multi-source data fusion, 3D modeling, and risk warning analysis, and displays the results.

10. The method according to claim 9, characterized in that, In the three-dimensional modeling step, CUDA-based parallel computing technology is used to accelerate the processing of massive point cloud data. In the risk warning analysis, the comprehensive factor value of each point cloud data is calculated according to different target requirements. By setting a risk warning threshold, the regions in the three-dimensional model are divided into different risk levels and marked with different colors according to the comprehensive factor values ​​of the point cloud data.

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