A physical simulation method, device and system for time domain electromagnetic method

Abstract

The present invention relates to the field of geophysical exploration technology, and in particular to a physical simulation method, device and system for a time domain electromagnetic method. The system comprises an electromagnetic signal transmitter, a DC stable power supply, a receiver and a transient electromagnetic signal acquisition instrument. The receiver is used to carry the surrounding rock part and the abnormal body part of the manufacturing material of the physical simulation model; the DC stable power supply is used to power the electromagnetic signal transmitter, and the electromagnetic signal transmitter is used to transmit a bipolar rectangular pulse current. The pulse width and off time of the bipolar rectangular pulse current are determined according to the time constant of the abnormal body part; and according to the parameter characteristics of the surrounding rock part, the diffusion distance of the transmitted signal in the surrounding rock part over time is determined, and a data collection time period is selected according to the diffusion distance. Then, the receiver synchronously collects electric field data and magnetic field data within the data collection time period through a receiving electrode and a flux gate arranged on its surface, and forwards the data to the transient electromagnetic signal acquisition instrument for analysis.

Description

Technical Field

[0001] The present invention relates to the field of geophysical exploration technology, and in particular to a physical simulation method, device and system of time domain electromagnetic method. Background Art

[0002] Time-domain borehole electromagnetic (TBE) combines the advantages and characteristics of conventional TDE and borehole geophysical methods. It has long been a key tool for deep resource and energy exploration, boasting high resolution, strong anti-interference capabilities, and deep exploration depths. Furthermore, it is highly efficient, low-cost, and adaptable to complex terrain for identifying reservoir fluid properties. However, due to limitations in observation conditions, further research is needed to understand the electromagnetic field distribution patterns of TBE, and the mapping between acquired electromagnetic field data and geological structures requires further study. Therefore, systematic research on this method through physical simulation is essential.

[0003] Because physical simulations are intuitive and repeatable, they have long been a powerful tool for studying the electromagnetic response of three-dimensional targets and verifying the reliability of methods. They serve as a foundation for electromagnetic exploration design and data interpretation, verifying method effectiveness, developing detection method designs, and optimizing and improving these designs. They are also a primary means of verifying numerical simulation results. Current research on time-domain electromagnetic physical simulations cannot meet similarity criteria, as frequency-domain physical simulations do, by significantly increasing the transmission frequency. Therefore, selecting appropriate model system performance indicators and experimental model materials on an adjustable time scale, as well as designing appropriate time-domain electromagnetic physical simulation methods, remains a major challenge in implementing time-domain electromagnetic physical simulations. Summary of the Invention

[0004] The purpose of the present invention is to provide a physical simulation method, device and system for time-domain electromagnetic method. By selecting appropriate model system performance indicators and experimental model materials, the time-varying characteristics of the time-domain magnetic field of the wellbore are simulated and studied, and the effectiveness and practicality of this method in actual deep earth exploration are demonstrated.

[0005] In order to achieve the above objectives, the technical solutions adopted in the embodiments of the present invention are as follows:

[0006] In a first aspect, an embodiment of the present invention provides a physical simulation method of a time domain electromagnetic method, the method comprising: determining a manufacturing material of a physical simulation model, the physical simulation model comprising a surrounding rock portion and an abnormal body portion; determining a pulse width and an off-time of a transmission signal that meets a preset transmission condition based on a time constant of the abnormal body portion, the preset transmission condition being that a distortion factor of received signal data is within a preset range; determining a diffusion distance of the transmission signal in the surrounding rock portion that changes with time based on parameter characteristics of the surrounding rock portion, and selecting a data acquisition time period based on the diffusion distance; controlling the transmission signal to be transmitted based on the pulse width and the off-time, and collecting signal data within the data acquisition time period for analysis, the signal data comprising electric field data and magnetic field data.

[0007] In the second aspect, an embodiment of the present invention further provides a physical simulation device of the time domain electromagnetic method, the device comprising: a first determination module for determining the manufacturing material of the physical simulation model, the physical simulation model comprising a surrounding rock part and an abnormal body part; a second determination module for determining the pulse width and off-time of the transmission signal that meets the preset transmission conditions based on the time constant of the abnormal body part, the preset transmission conditions being that the distortion factor of the received signal data is within a preset range; a third determination module for determining the diffusion distance of the transmission signal in the surrounding rock part as it changes with time based on the parameter characteristics of the surrounding rock part, and selecting a data acquisition time period based on the diffusion distance; a control module for controlling the transmission signal to be transmitted according to the pulse width and off-time, and collecting signal data within the data acquisition time period for analysis, the signal data comprising electric field data and magnetic field data.

[0008] In the third aspect, an embodiment of the present invention also provides a physical simulation system of the time domain electromagnetic method, which includes an electromagnetic signal transmitter, a DC stable power supply, a receiver, and a transient electromagnetic signal collector. The receiver is used to carry the manufacturing materials of the physical simulation model, and the manufacturing materials include a surrounding rock part and an abnormal body part; the DC stable power supply is used to power the electromagnetic signal transmitter; the electromagnetic signal transmitter is used to transmit a bipolar rectangular pulse current, and the pulse width and off time of the bipolar rectangular pulse current are determined according to the time constant of the abnormal body part; the receiver synchronously collects electric field data and magnetic field data through receiving electrodes and flux gates arranged on its surface, and forwards them to the transient electromagnetic signal collector for analysis. The time period for the receiver to collect the electric field data and magnetic field data is determined according to the parameter characteristics of the surrounding rock part.

[0009] Embodiments of the present invention provide a physical simulation method, device, and system for time-domain electromagnetic method. The system includes an electromagnetic signal transmitter, a DC stabilized power supply, a receiver, and a transient electromagnetic signal acquisition instrument. The receiver is used to carry the materials used to make the physical simulation model - the surrounding rock portion and the anomaly portion. The DC stabilized power supply is used to power the electromagnetic signal transmitter, which is used to transmit a bipolar rectangular pulse current. The pulse width and off-time of the bipolar rectangular pulse current are determined based on the time constant of the anomaly portion to ensure that the distortion factor of the received data signal is within a preset range. The electromagnetic signal transmitter also determines the diffusion distance of the transmitted signal in the surrounding rock portion over time based on the parameter characteristics of the surrounding rock portion, and selects a data collection time period based on the diffusion distance. The receiver then synchronously collects electric field data and magnetic field data during the data collection time period through receiving electrodes and fluxgates provided on its surface, and forwards the data to the transient electromagnetic signal acquisition instrument for analysis. This solution selects model materials for the physical simulation system to form a model, and sets the parameters of the transmitted signal and received signal data based on the material characteristics. This solution can effectively simulate and study the mapping relationship between electromagnetic field data and geological structure, and has high practical value in geological exploration.

[0010] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0012] Figure 1 A schematic flow chart of a physical simulation method of a time-domain electromagnetic method provided by an embodiment of the present invention is shown.

[0013] Figure 2 A schematic diagram of functional modules of a physical simulation device for a time-domain electromagnetic method provided by an embodiment of the present invention is shown.

[0014] Figure 3 A schematic structural diagram of a physical simulation system of a time-domain electromagnetic method provided by an embodiment of the present invention is shown.

[0015] Figure 4 A structural schematic diagram from another perspective of a physical simulation system of a time-domain electromagnetic method provided by an embodiment of the present invention is shown.

[0016] Diagram:

[0017] 100 - physical simulation device for time-domain electromagnetic method; 110 - first determination module; 120 - second determination module; 130 - third determination module; 140 - control module; 200 - physical simulation system for time-domain electromagnetic method; 210 - electromagnetic signal transmitter; 220 - DC stabilized power supply; 230 - receiver; 240 - transient electromagnetic signal acquisition instrument; 231 - copper ball; 232 - graphite block; 233 - organic glass shell; 234 - transmitting electrode frame; 235 - receiving electrode frame; 236 - transmitting electrode; 237 - receiving electrode; 238 - flux gate. DETAILED DESCRIPTION

[0018] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. The components of the embodiments of the present invention generally described and shown in the drawings herein can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present invention.

[0019] It should be noted that similar reference numerals and letters represent similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings. At the same time, in the description of the present invention, the terms "first", "second", etc. are used only to distinguish the description and should not be understood as indicating or implying relative importance.

[0020] Currently, strengthening domestic exploration and development of important energy and mineral resources and increasing reserves and production are key goals of China's mineral resource exploration. Time-domain borehole electromagnetics combines the advantages and characteristics of conventional time-domain electromagnetics and borehole geophysical methods, offering high resolution, strong anti-interference capabilities, and deep exploration depths. It can be used to identify reservoir fluid properties with high efficiency, low cost, and effective adaptation to complex terrain. However, this method is not yet fully mature and requires further research. This proposal simulates the application of this time-domain borehole electromagnetic method to geographic exploration, demonstrating its effectiveness and practicality in deep-earth exploration, and providing assistance and reference for deep-earth resource exploration.

[0021] Please refer to Figure 1 , is a flow chart of a physical simulation method of a time-domain electromagnetic method provided by an embodiment of the present invention, the method comprising:

[0022] S110, determining the manufacturing material of the physical simulation model, wherein the physical simulation model includes a surrounding rock portion and an abnormal body portion.

[0023] Specifically, the physical simulation of the time-domain electromagnetic method needs to follow similarity criteria and be reduced to a certain scale (such as 1:100 to 1:1000000) under laboratory conditions to simulate the electromagnetic response of the underground medium and observe its changing patterns.

[0024] The similarity criterion is subdivided into the time domain and the frequency domain, and the specific similarity criterion is:

[0025] l′ 2 / ρ′t′=l 2 / ρt

[0026] Among them, the ones with ' represent the physical simulation model parameters, those without ' represent the field system parameters, ρ is the resistivity, t is the time, and I is the linear scale.

[0027] It should be noted that the physical simulation of the time-domain electromagnetic method is more challenging than the physical simulation of the frequency-domain electromagnetic method. Because the observation data of this method collects fields that change with time, neither the time of the model system (t′) nor the time of the field system (t) can be compressed and adjusted according to the scale of similar principles. In other words, the physical simulation model of the time-domain electromagnetic method cannot meet the requirement of reducing the size of the model by hundreds of times by increasing the transmission frequency of the model system by 4-5 orders of magnitude, as the physical simulation of the frequency-domain electromagnetic method can do. Instead, the model can only be made of materials with a resistivity 4-5 orders of magnitude lower. In addition, the performance indicators of the model system's transceiver hardware and the experimental site are more demanding. Therefore, in this solution, it is necessary to first determine the materials for the physical simulation model to construct the physical simulation model of the time-domain electromagnetic method for simulation experiments.

[0028] Based on the aforementioned similarity criteria, and taking into account the scale of the simulated deep ore body and experimental hardware conditions, the physical simulation model was set to have the same time t as the field system, and the linear scale l was designed to be 1:2500. Solid, highly conductive materials were used to simulate the surrounding rock, and metals with resistivity that differed by 2-3 orders of magnitude from the surrounding rock were used to simulate the anomalous bodies. The surrounding rock can be a geological structure, and the anomalous bodies can be ore bodies or other geological resources within the geological structure.

[0029] Electromagnetic simulations often use conductive solutions to simulate surrounding rock, and solids such as paraffin wax to simulate anomalies. When these solids come into contact with conductive solutions, the induced polarization effects generated at the solid-liquid interface or in the liquid-filled pores of the solid cannot be ignored at low frequencies. Therefore, this solution uses a solid, highly conductive material to simulate the surrounding rock and a metal to simulate the anomaly. Furthermore, the sampling time of this physical simulation model is in the millisecond range, which effectively reduces the induced polarization effect.

[0030] Furthermore, in this scheme, the impedance of the graphite block and graphite powder was measured using an SI-1260 impedance / phase analyzer, and the resistivity of the graphite block was calculated to be 1.02×10 -5 Ω·m, and the resistivity of graphite powder is 0.076Ω·m. It can be seen that the resistivity of the graphite block formed by compacting and sintering the graphite powder can well meet the parameter design requirements of the time domain electromagnetic method physical simulation model (as shown in Table 1). Therefore, considering the resistivity, plasticity, processing technology, performance and price, the physical simulation model chooses graphite blocks to simulate the surrounding rock part, and copper with lower resistivity (ρ = 1.75×10 -8 Ω·m) to simulate the abnormal body. It is easy to understand that other materials can also be selected to simulate the surrounding rock part and the abnormal body part according to the requirements of different experiments.

[0031] Table 1 Parameter design of time domain electromagnetic method physical simulation model

[0032]

[0033] S120 , determining a pulse width and an off time of a transmission signal that meets a preset transmission condition based on a time constant of the abnormal body portion, wherein the preset transmission condition is that a distortion factor of received signal data is within a preset range.

[0034] Specifically, after determining the materials for the physical simulation model and completing the construction of the physical simulation model, it is necessary to determine the parameters of the transmission signal. How the transmission signal is transmitted needs to consider that the distortion factor of the signal data received by the receiving end is within a preset range. Furthermore, the distortion factor is the ratio of the observed value of the experimental acquisition signal to the theoretical value under a single step signal. In order to make the observed value collected by the physical simulation model closer to the theoretical value, the distortion factor D f Need to meet: 0.9 <D f <1. Furthermore, reducing the pulse width d of the transmitting signal or increasing the off time t of All of these will distort the experimental observations and deviate from the theoretical values, so the pulse width and off-time of the emission signal must be set appropriately. Since the decay rate of the emission signal is related to the time constant τ of the abnormal body part of the physical simulation model, in order to achieve 0.9<D f<1, can be set τ / d<0.4, t of / τ≤0.01.

[0035] Furthermore, the time constant τ of the abnormal body portion can be determined based on the vacuum magnetic permeability of the abnormal body portion, the diameter of the abnormal body portion, and the resistivity of the abnormal body portion. Taking the abnormal body as a copper ball as an example, the time constant τ is calculated as follows:

[0036] τ=μ0a 2 / ρ Cu π 2

[0037] Where μ0 is the vacuum permeability, ρ Cu is the resistivity of the copper ball, and a is the diameter of the copper ball. For example, when all parameters are clear, the time constant τ can be calculated to be about 26ms. f <1, according to τ / d<0.4, t of / τ≤0.01, the pulse width can be calculated as d>65ms, and the off time t of ≤0.26ms.

[0038] S130 , determining a diffusion distance of the transmitted signal in the surrounding rock portion over time according to parameter characteristics of the surrounding rock portion, and selecting a data acquisition time period according to the diffusion distance.

[0039] Specifically, since the transient field (i.e., the emission signal) may not accurately reflect the information of the underground abnormal body in the early stage, it is not necessary to collect the emission signal in all time periods, and thus it is necessary to select a reasonable data collection time period. In the embodiment of the present invention, the diffusion distance of the emission signal in the surrounding rock part over time is determined based on the parameter characteristics of the surrounding rock part, and then the data collection time period is selected based on the rate of change of the diffusion distance. Taking the surrounding rock part as a graphite block as an example, for any time t, the diffusion distance δ of its emission signal in the graphite is:

[0040]

[0041] Among them, the parameter characteristics of the surrounding rock part include the resistivity ρ of the graphite block C , vacuum magnetic permeability μ0. By selecting different times t, the diffusion distance of the transmitted signal at different times can be obtained, as shown in Table 2. As can be seen from the table, the diffusion distance of the transmitted signal is small in the early moments and begins to increase within the 1-10 ms period. Therefore, in this scheme, the 1-10 ms period after the pulse is turned off is selected as the data collection period, and signal collection and analysis begins within this data collection period.

[0042] Table 2 Transient field diffusion distance of the physical simulation model at different times

[0043]

[0044] In order to verify the rationality of the selection of the data acquisition time period, this program also uses the existing time-domain finite-time-domain electromagnetic forward modeling program to perform a one-dimensional simulation of the physical simulation model. It should be noted that the so-called electromagnetic forward modeling is a geophysical forward modeling using electromagnetic correlation methods. Geophysical exploration methods are scientific tools for humans to explore unknown underground structures. Whether it is gravity, magnetic or electric or seismic, different geophysical exploration methods need to solve forward and inversion problems. For electromagnetic exploration methods, the forward modeling problem aims to solve the electric field component and magnetic field component on the coordinate by solving the Maxwell equations under the premise of knowing the electrical parameters of the formation structure. Therefore, we choose the forward modeling method to verify whether the above parameter settings (pulse width, off time, data acquisition time period) are reasonable.

[0045] Specifically, the electric line source is set to be 0.05m long, 0.725m deep, and placed at the center of the cross section of the physical simulation model. The emission current amplitude is 10A, the pulse width is 65ms, the off time is 20μs, the duty cycle is 1:1, and the size of the graphite block is 2m×2m×1.5m. The simulation results show that the electric field response value is 10 -6 -10 -7 V / m, reduced to 10 at 70ms -7 V / m or less. The simulation results show again that the experimental pulse width d>65ms and the turn-off time t of The parameters such as ≤0.26ms and the selection range of the starting sampling time of 1-10ms are reasonably set. The amplitude and decay time of the transient field obtained can meet the experimental observation requirements of the three-component response characteristics of the electromagnetic field at the observation point and the diffusion law of the transient field, thereby proving that the physical simulation model provided by this scheme is feasible.

[0046] S140, controlling the transmission signal to be transmitted according to the pulse width and the off time, and collecting signal data within the data collection time period for analysis, wherein the signal data includes electric field data and magnetic field data.

[0047] Specifically, after verifying that the above-mentioned parameters such as pulse width, off time, and data collection time period are reasonably set and feasible, the transmitter can be controlled to transmit the signal according to the value range of the pulse width and off time, and the pulse width and off time with reasonable values ​​can be selected. At the same time, the receiver is controlled to collect and analyze the signal data, including electric field data and magnetic field data, within the selected data collection time period to study the mapping relationship between the electromagnetic field data and the geological structure in the physical simulation model, thereby providing a reference for actual geographical exploration.

[0048] It should be noted that the physical simulation in the specific implementation process of this solution includes two types: without terrain simulation and with terrain simulation.

[0049] This method without terrain simulation uses a graphite block with a regular shape and a flat surface. First, the first signal data of the graphite block is measured as a background field study. Then, after the copper ball is embedded in the graphite block, the second signal data is collected for the entire block after embedding, and then the first signal data and the second signal data are combined for analysis.

[0050] This belt topography simulation involves placing another graphite block with a designed trapezoidal or grooved shape on top of a graphite block to simulate different terrains, such as horsts or grabens. Alternatively, different terrains can be simulated directly on the top of the graphite block, creating different structures or rough surfaces. Signal data from the configured graphite blocks and / or copper balls is then collected and analyzed.

[0051] Thus, this scheme can select appropriate materials to establish a model based on the characteristics of the physical simulation of the time-domain electromagnetic method and the similarity criterion. This scheme mainly selects the surrounding rock part of the physical simulation model as a graphite block and the abnormal body part as a copper ball for example. It is easy to understand that according to different geological environments or experimental requirements, other materials can be selected for experimental operation if they can meet the application. However, the parameters of the transmitted signal, such as the pulse width and off time, and the receiving end data acquisition time, are all determined according to the calculation logic provided by this scheme. It can be seen that through the physical simulation method of the time-domain electromagnetic method provided by this scheme, a physical simulation model can be well established and reasonable parameters can be determined to better study the temporal variation characteristics of the time-domain electromagnetic field and demonstrate the effectiveness and practicality of this method in deep earth exploration.

[0052] See Figure 2 , is a structural diagram of a physical simulation device 100 of a time domain electromagnetic method provided by an embodiment of the present invention. The device includes a first determination module 110, a second determination module 120, a third determination module 130 and a control module 140.

[0053] The first determination module 110 is used to determine the manufacturing material of the physical simulation model, where the physical simulation model includes a surrounding rock part and an abnormal body part.

[0054] In the embodiment of the present invention, S110 may be performed by the first determining module 110 .

[0055] The second determining module 120 is configured to determine a pulse width and an off time of a transmission signal that meets a preset transmission condition based on a time constant of the abnormal body portion, wherein the preset transmission condition is that a distortion factor of the received signal data is within a preset range.

[0056] In the embodiment of the present invention, S120 may be performed by the second determining module 120 .

[0057] The third determination module 130 is configured to determine a diffusion distance of the emission signal in the surrounding rock portion that varies with time based on parameter characteristics of the surrounding rock portion, and select a data acquisition time period based on the diffusion distance.

[0058] In the embodiment of the present invention, S130 may be performed by the third determining module 130 .

[0059] The control module 140 is used to control the transmission signal to be transmitted according to the pulse width and the off time, and to collect signal data within the data collection time period for analysis, wherein the signal data includes electric field data and magnetic field data.

[0060] In the embodiment of the present invention, S140 may be executed by the control module 140 .

[0061] Since the physical simulation method of the time domain electromagnetic method has been described in detail, it will not be repeated here.

[0062] Please refer to Figure 3 , which is a structural diagram of a physical simulation system 200 of a time domain electromagnetic method provided by an embodiment of the present invention, please refer to Figure 4 , is a structural diagram from another perspective of a physical simulation system 200 of a time-domain electromagnetic method provided by an embodiment of the present invention.

[0063] The physical simulation system includes an electromagnetic signal transmitter 210 , a DC stable power supply 220 , a receiver 230 and a transient electromagnetic signal collector 240 .

[0064] The DC stabilized power supply 220 is used to supply power to the electromagnetic signal transmitter 210 .

[0065] The electromagnetic signal transmitter 210 is used to transmit a bipolar rectangular pulse current with a duty cycle of 1:1. The pulse width and off time of the bipolar rectangular pulse current are determined according to the calculation method in the above method.

[0066] In this embodiment, the receiver 230 is constructed by combining a graphite block and a copper ball. As will be readily understood, the selected material combination can be varied based on practical needs, provided that the resistivity requirements described above are met. Specifically, the receiver 230 pre-embeds a copper ball 231 and a transmitting electrode 236 with a long wire into a graphite block 232. After sintering, the receiver 230 is encapsulated within a plexiglass housing 233. The surface of the receiver 230 is provided with a transmitting electrode frame 234 and a receiving electrode frame 235. The transmitting electrode frame 234 supports the transmitting electrode 236 and the wires connecting the transmitting electrode 236 to the electromagnetic signal transmitter 210. The receiving electrode frame 235 supports the receiving electrode 237 and the wires connecting the receiving electrode 237 to the transient electromagnetic signal acquisition instrument 240. Furthermore, a fluxgate 238 is provided on the surface of the receiver 230. The receiving electrode 237 and the fluxgate 238 respectively synchronously collect electric field data and magnetic field data, and forward them to the transient electromagnetic signal acquisition instrument 240 for analysis. The time period for the receiver 230 to collect signal data is determined according to the data collection time period determined by the above method.

[0067] Furthermore, the receiving electrode 237 is fixed to the surface of the receiver 230 via a receiving electrode frame 235 with scales, and can be moved on the surface to facilitate the collection of electric field data at different positions.

[0068] Furthermore, when comparing copper, silver and platinum electrodes, the resistivity of platinum electrodes is low, which is 9×10 -8 Ω·m, and due to its superior physical and chemical stability and corrosion resistance, platinum wire electrodes were selected as receiving electrodes 237. The fluxgate 238 uses the currently smaller Mag612U three-axis fluxgate probe, which measures 0.02m×0.02m×0.02m, has a measurement range of ±90μT, and a linear error of 0.0015%, effectively meeting the requirements for magnetic field signal acquisition.

[0069] Furthermore, the physical simulation of the time-domain electromagnetic method requires not only strict control of parameters such as the output power, waveform, and frequency of the emitted transient current, but also high precision, sensitivity, and reliability of the acquired signal. Considering various factors, including the instrument's transmit power, transmitted signal pulse width, off-time, and adaptability to the physical simulation, the preferred model for this proposal is the IGGETEM time-domain electromagnetic instrument. This instrument's transmitter features bipolar transmission, fast off-time, and linear falling edge. The receiver also boasts fast sampling speed, low noise, and a wide dynamic range. The modification effort is relatively simple; simply replacing the transmitting coil with a finite-length current source and converting the magnetic track of the receiving section of the instrument to an electrical track allows for the experiment to proceed. For example, the experimental procedure can be as follows: set the transmit current to 10-25A, the pulse width to 65-100ms, the off-time to 20μs, and the receiver sampling rate to 10μs. 4-10 measuring lines are arranged on the surface of the graphite body to collect the electric field, with a line spacing of 10-20cm. Each measuring line is arranged with 15-30 measuring points, with a point spacing of 5-10cm, to collect the electric field in the x and y directions respectively. With a line spacing of 40-80cm and a point spacing of 25-50cm, a micro fluxgate is used to collect the three components of the magnetic field. Various types of simulation data are collected and processed to complete the physical simulation. In other words, after setting up the instrument transmitter and confirming the transmission and reception parameters according to the above method, multiple test lines can be arranged at different locations on the graphite body (surrounding rock part) according to experimental requirements to detect electric field data. At the same time, without affecting the electric field wiring, multiple magnetic field test lines are arranged to detect magnetic field data to complete the physical simulation.

[0070] In summary, the embodiments of the present invention provide a physical simulation method, device, and system for time-domain electromagnetic method, wherein the system includes an electromagnetic signal transmitter, a DC stabilized power supply, a receiver, and a transient electromagnetic signal acquisition instrument. The receiver is used to carry the manufacturing materials of the physical simulation model, and the manufacturing materials include a surrounding rock part and an abnormal body part; the DC stabilized power supply is used to power the electromagnetic signal transmitter, and the electromagnetic signal transmitter is used to transmit a bipolar rectangular pulse current. The pulse width and off time of the bipolar rectangular pulse current are determined according to the time constant of the abnormal body part to ensure that the distortion factor of the received data signal is within a preset range; and Based on the parameter characteristics of the surrounding rock part, the diffusion distance of the transmitted signal in the surrounding rock part over time is determined, and the data collection time period is selected based on the diffusion distance. Then, the receiver will synchronously collect electric field data and magnetic field data during the data collection period through the receiving electrodes and flux gates set on its surface, and forward them to the transient electromagnetic signal acquisition instrument for analysis. This scheme selects the model material of the physical simulation system to build a model, and sets the parameters of the transmitted signal and the received signal data according to the material characteristics. It can better simulate and study the mapping relationship between electromagnetic field data and geological structure, and has high practical value in geological exploration.

[0071] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can also be implemented in other ways. The device embodiments described above are merely illustrative. For example, the flowcharts and block diagrams in the accompanying drawings show the possible architectures, functions and operations of the devices, methods and computer program products according to multiple embodiments of the present invention. In this regard, each box in the flowchart or block diagram can represent a module, a program segment or a portion of code, and the module, program segment or a portion of code contains one or more executable instructions for implementing the specified logical function. It should also be noted that in some alternative implementations, the functions marked in the box can also occur in an order different from that marked in the accompanying drawings. For example, two consecutive boxes can actually be executed substantially in parallel, and they can sometimes be executed in the opposite order, depending on the functions involved. It should also be noted that each box in the block diagram and / or flowchart, and the combination of boxes in the block diagram and / or flowchart, can be implemented using a dedicated hardware-based system that performs the specified function or action, or can be implemented using a combination of dedicated hardware and computer instructions.

[0072] In addition, the functional modules in the various embodiments of the present invention may be integrated together to form an independent part, or each module may exist independently, or two or more modules may be integrated to form an independent part.

[0073] If the functions are implemented in the form of software function modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product, which is stored in a storage medium and includes several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. It should be noted that, in this article, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprise", "include" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, the elements defined by the phrase "comprising a..." do not exclude the presence of other identical elements in the process, method, article or device comprising the elements.

[0074] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Various modifications and variations are readily apparent to those skilled in the art. Any modifications, equivalent substitutions, improvements, and the like made within the spirit and principles of the present invention are intended to be included within the scope of protection of the present invention. It should be noted that similar reference numerals and letters denote similar items in the following figures. Therefore, once an item is defined in one figure, it need not be further defined or explained in subsequent figures.

[0075] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A physical simulation method of time domain electromagnetic method, characterized in that: The method includes: determining a manufacturing material of a physical simulation model, wherein the physical simulation model includes a surrounding rock portion and an abnormal body portion; determining a pulse width and an off time of a transmission signal that meets a preset transmission condition based on a time constant of the abnormal body portion, wherein the preset transmission condition is that a distortion factor of received signal data is within a preset range; determining a diffusion distance of the transmission signal in the surrounding rock portion that changes with time based on parameter characteristics of the surrounding rock portion, and selecting a data acquisition time period based on the diffusion distance; controlling the transmission signal to be emitted based on the pulse width and the off time, and collecting signal data within the data acquisition time period for analysis, wherein the signal data includes electric field data and magnetic field data.

2. The method according to claim 1, wherein The step of determining the material for making the physical simulation model, wherein the physical simulation model includes a surrounding rock part and an abnormal body part, comprises: referring to the field system based on similarity criteria, determining that the surrounding rock part of the physical simulation model uses a solid well-conductive material, and the abnormal body part uses a metal whose resistivity differs by 2-3 orders of magnitude from the material of the surrounding rock part.

3. The method according to claim 2, wherein The material of the surrounding rock part of the physical simulation model is selected as graphite block, and the material of the abnormal body part is selected as metal copper.

4. The method according to claim 1, wherein The method for determining the time constant of the abnormal body portion includes: determining the time constant of the abnormal body portion according to the vacuum magnetic permeability of the abnormal body portion, the diameter of the abnormal body portion, and the resistivity of the abnormal body portion.

5. The method according to claim 1, wherein The steps of determining the diffusion distance of the transmitted signal in the surrounding rock portion as it changes over time based on the parameter characteristics of the surrounding rock portion, and selecting a data acquisition time period based on the diffusion distance include: determining the diffusion distance of the transmitted signal in the surrounding rock portion as it changes over time based on the resistivity and vacuum permeability of the surrounding rock portion; and selecting a data acquisition time period based on the rate of change of the diffusion distance.

6. The method according to claim 1, wherein The physical simulation includes no terrain simulation, and the method further includes: using the surrounding rock part with a regular shape and a flat surface, and collecting first signal data of the surrounding rock part; after embedding the abnormal body part in the surrounding rock part, collecting second signal data of the surrounding rock part and the abnormal body part in the overall state; combining the first signal data and the second signal data to analyze the physical simulation model.

7. The method according to claim 1, wherein The physical simulation includes terrain simulation, and the method further includes: simulating different terrains to set the top surface of the surrounding rock portion into different shapes; and collecting signal data of the surrounding rock portion and / or the abnormal body portion.

8. A physical simulation device for time domain electromagnetic method, characterized in that: The device includes: a first determination module for determining the manufacturing material of the physical simulation model, wherein the physical simulation model includes a surrounding rock part and an abnormal body part; a second determination module for determining the pulse width and off time of the transmission signal that meets the preset transmission condition based on the time constant of the abnormal body part, wherein the preset transmission condition is that the distortion factor of the received signal data is within a preset range; a third determination module for determining the diffusion distance of the transmission signal in the surrounding rock part that changes with time based on the parameter characteristics of the surrounding rock part, and selecting a data acquisition time period based on the diffusion distance; and a control module for controlling the transmission signal to be transmitted according to the pulse width and off time, and collecting signal data within the data acquisition time period for analysis, wherein the signal data includes electric field data and magnetic field data.

9. A physical simulation system for time domain electromagnetic method, characterized in that: The system includes an electromagnetic signal transmitter, a DC stabilized power supply, a receiver, and a transient electromagnetic signal collector. The receiver is used to carry the manufacturing materials of the physical simulation model, and the manufacturing materials include a surrounding rock part and an abnormal body part. The DC stabilized power supply is used to power the electromagnetic signal transmitter. The electromagnetic signal transmitter is used to transmit a bipolar rectangular pulse current. The pulse width and off time of the bipolar rectangular pulse current are determined according to the time constant of the abnormal body part, and the transmission conditions of the pulse width and off time of the bipolar rectangular pulse current must meet the distortion factor of the received signal data within a preset range. The receiver synchronously collects electric field data and magnetic field data through receiving electrodes and fluxgates provided on its surface, and forwards them to the transient electromagnetic signal collector for analysis. The time period for the receiver to collect the electric field data and magnetic field data is determined according to the parameter characteristics of the surrounding rock part. Specifically, the diffusion distance of the bipolar rectangular pulse current in the surrounding rock part as it changes with time is determined according to the parameter characteristics of the surrounding rock part, and the data collection time period is selected according to the diffusion distance.

10. The system according to claim 9, wherein: The abnormal body is partially embedded in the surrounding rock, and the transmitting electrode connected to the electromagnetic signal transmitter is also embedded in the surrounding rock; the receiving electrode is fixed by an electrode frame with a scale and is movably arranged relative to the receiver surface.

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