Exploration method of frequency division electrical method based on frequency conversion signal

Abstract

The invention relates to an exploration method of a frequency division electrical method based on a frequency conversion signal, and belongs to the technical field of electrical method exploration, and the method comprises the steps: determining the frequency value and the frequency number of the frequency transmitted by each channel of a multi-channel frequency division electrical method transmitter based on an exploration purpose and an exploration requirement; frequency conversion signals are sent to the underground by using each channel of the multi-channel frequency division electrical method transmitter; obtaining a current value of each frequency sent by each channel of the multi-channel frequency division electrical method transmitter at the mobile power supply point; obtaining potential differences of different frequencies measured by the multichannel frequency division electrical method receiver on the measuring electrode pair and phase differences of potential differences of corresponding frequencies relative to power supply currents of the same frequency; determining device coefficients based on the measuring electrode pairs and the coordinates of all the mobile power supply points; calculating apparent resistivity based on an apparent resistivity parameter formula corresponding to the electrode device; and obtaining an interpretation result based on the apparent resistivity and the phase difference. The method has the effect of comprehensively and accurately collecting the geoelectricity information.

Description

Technical Field

[0001] The present application relates to the technical field of electrical prospecting, and in particular to an exploration method using frequency division electrical prospecting based on variable frequency signals. Background Art

[0002] With the continuous advancement of science and technology, the field of electrical exploration is constantly pursuing the dual improvement of exploration effects and exploration efficiency. In this process, data identification, data representation and other links play a vital role.

[0003] Among the many electrical exploration technologies, single-frequency signal frequency division electrical exploration stands out for its unique advantages. This technology uses a transmitter to transmit a single-frequency power supply current signal to each channel. The current signal frequencies passing through different channels vary. In terms of data recognition, the receiving device can accurately identify the electrical signal data collected by each channel based on the preset frequency characteristics of each channel, thereby distinguishing the response information from different locations or geological conditions. In terms of data representation, the collected electrical signal data is stored and transmitted in a specific digital code format. Compared with traditional methods, single-frequency signal frequency division electrical exploration has demonstrated significant results in improving exploration effectiveness, reducing costs, and accelerating exploration progress.

[0004] While frequency division methods, which generate a single-frequency signal with a constant current value at the same frequency when each channel of a multi-channel frequency division electrical method transmitter is powered by a single power supply point, offer many advantages, they also have limitations, particularly limited exploration accuracy. This makes them difficult to achieve optimal results when faced with exploration tasks that require higher precision and more detailed information. Therefore, how to overcome the limitations of single-frequency signals while maintaining exploration efficiency and achieving comprehensive and accurate geoelectrical information collection has become a key issue that needs to be addressed in the field of electrical exploration. Summary of the Invention

[0005] In order to solve the above problems, the present application provides a prospecting method based on frequency division method of variable frequency signal, which adopts the following technical solutions:

[0006] A prospecting method based on frequency division electrical method of variable frequency signal, comprising:

[0007] Determining, based on the exploration objectives and requirements, the frequency value and number of frequencies transmitted by each channel of the multi-channel frequency division electrical transmitter, wherein the number of frequencies is not less than the number of channels of the multi-channel frequency division electrical transmitter, and the frequency value and number of frequencies transmitted by each channel of the multi-channel frequency division electrical transmitter are the same;

[0008] Determine the number of mobile power supply points using an electrode device based on the resistivity profile method;

[0009] Utilizing each channel of the multi-channel frequency division electric method transmitter to transmit a variable frequency signal underground;

[0010] Obtaining a current value of each frequency in the frequency conversion signal transmitted by each channel of the multi-channel frequency division current transmitter at the mobile power supply point;

[0011] Acquire the potential differences of different frequencies measured on the measuring electrode pair by a multi-channel frequency division method receiver synchronized in time with the multi-channel frequency division method transmitter, and the phase difference of the potential differences of the corresponding frequencies relative to the supply current of the same frequency;

[0012] measuring the coordinates of all measuring electrode pairs and all mobile power supply points, and determining device coefficients for coordinate conversion based on the coordinates;

[0013] Obtaining a parameter formula for apparent resistivity corresponding to the electrode device;

[0014] Calculating the apparent resistivity based on the apparent resistivity parameter formula;

[0015] Analyze the apparent resistivity and phase difference of all measuring electrodes at all frequencies to obtain the exploration and interpretation results;

[0016] The characteristics of the frequency conversion signal transmitted by each channel of the multi-channel frequency division multiplexing transmitter meet the following requirements:

[0017] Each channel sends only one of the selected transmission frequencies at a certain moment; the frequency values ​​of the variable frequency signals sent by each channel are different at the same moment; the sending time length of a certain frequency in the variable frequency signals sent by each channel is an integer multiple of one cycle of the frequency; the variable frequency signals sent by each channel contain all the selected frequencies.

[0018] By adopting the above technical solution, the variable frequency signal sent by each channel contains multiple frequencies, and the transmission time length of these frequencies is an integer multiple of the period, ensuring that the geoelectric response at different frequencies can be fully collected; since each channel only sends one of the selected frequencies at the same time, and the frequency values ​​of each channel at the same time are different, the problem of signal interference can be reduced, thereby improving the accuracy of data collection; the frequency values ​​in each channel are different at the same time, and each channel will pass through all frequency values, it is possible to obtain results of different frequencies at the same measuring point, realizing fine exploration; by selecting multiple frequencies, a wider frequency range can be covered, thereby obtaining the resistivity and phase information of the underground medium at different frequencies, and realizing a comprehensive characterization of complex geological structures.

[0019] Optionally, the electrode device includes one of a quadrupole device, a tripolar device, and a bipolar device, and determining the number of mobile power supply points using the electrode device based on the resistivity profile method includes:

[0020] In the case of a quadrupole electrode device, the number of mobile power supply points deployed in the exploration area shall not be less than twice the number of channels of the multi-channel frequency division method transmitter;

[0021] When the electrode device adopts a three-pole device or a two-pole device, in addition to the infinite power supply point, the number of mobile power supply points deployed in the exploration area shall not be less than the number of channels of the transmitter of the multi-channel frequency division method, and the number of mobile power supply points shall be an integer multiple of the number of channels of the transmitter of the multi-channel frequency division method.

[0022] By adopting the above technical solution, when using a four-pole device, the number of mobile power supply points is not less than twice the number of channels of the multi-channel frequency division method transmitter, so that the power supply points connected to each channel are different, and a denser distribution of power supply points can be obtained, thereby improving the sampling density of the underground medium in the exploration area; the number of mobile power supply points of the three-pole device and the two-pole device is not less than the number of channels of the multi-channel frequency division method transmitter, while ensuring data coverage, reducing unnecessary redundant measurements and improving operation efficiency; by reasonably configuring the number of mobile power supply points, each channel sends signals at different power supply points at the same time, fully utilizing the advantages of the multi-channel frequency division method, significantly shortening the data acquisition time, setting the minimum number of power supply points according to the type of electrode device, avoiding excessive redundant measurements, and at the same time ensuring data integrity and improving overall operation efficiency.

[0023] Optionally, obtaining the current value of each frequency transmitted by each channel of the multi-channel frequency division current transmitter at the mobile power supply point includes:

[0024] In the case where the electrode device adopts a quadrupole device, each channel of the multi-channel frequency division method transmitter is obtained at each pair of mobile power supply points. The current value of each frequency sent , Indicates the number of a pair of mobile power supply points, , r4 is the number of mobile power supply points of the four-pole device, For a pair of mobile power supply points The frequency value sent; where [1, p], where p is the total number of frequencies transmitted by each channel of the multi-channel frequency division multiplexing transmitter;

[0025] In the case where the electrode device adopts a three-pole device or a two-pole device, the current value of each frequency sent by each channel of the multi-channel frequency division method transmitter at each mobile power supply point and infinite power supply point is obtained. , Indicates the number of a mobile power supply point. , Number of mobile power supply points for three-pole installations, Number of mobile power supply points for two-pole devices, For a mobile power supply point The frequency value sent by the fixed infinite power supply point; [1, p]; p is the total number of frequencies transmitted by each channel of the multi-channel frequency division multiplexing transmitter.

[0026] Optionally, before obtaining the potential differences of different frequencies measured on the measuring electrode pair by the multi-channel frequency division method receiver synchronized with the multi-channel frequency division method transmitter, the method further includes:

[0027] In the case where the electrode device adopts a four-pole device or a three-pole device, a multi-channel frequency division method receiver is used to measure the potential of different frequencies on the measuring electrode M and the measuring electrode N, wherein the measuring electrode M and the measuring electrode N constitute a measuring electrode pair, and the measurement time on each pair of measuring electrodes is not less than the total time length of all frequencies transmitted by the multi-channel frequency division method transmitter;

[0028] In the case where the electrode device adopts a two-pole device, a multi-channel frequency division electrical method receiver is used to measure the potentials of different frequencies on a certain measuring electrode M and a fixed infinitely distant measuring electrode, wherein the measuring electrode M and the infinitely distant measuring electrode form a measuring electrode pair, and the measured time on each pair of measuring electrodes is not less than the total time length of all frequencies transmitted by the multi-channel frequency division electrical method transmitter.

[0029] By adopting the above technical solution, the measurement time on each pair of measuring electrodes is not less than the total time of the multi-channel frequency division method transmitter sending all frequencies, and the measurement results of all frequencies can be obtained, avoiding data loss due to insufficient measurement time.

[0030] Optionally, the step of obtaining the potential differences of different frequencies measured on a measuring electrode pair by a multi-channel frequency division method receiver that is time-synchronized with the multi-channel frequency division method transmitter, and the phase difference of the potential differences of the corresponding frequencies relative to a supply current of the same frequency, includes:

[0031] When the electrode device adopts a quadrupole device, the potential difference of different frequencies supplied by the corresponding mobile power supply points on all measuring electrodes M and measuring electrode N is measured when the mobile power supply point in the exploration area supplies power. And the potential difference of the corresponding frequency relative to the phase difference of the supply current of the same frequency ;

[0032] When the electrode device adopts a three-pole device, the potential difference of different frequencies supplied by the corresponding power supply points on all measuring electrodes M and measuring electrodes N is measured when the mobile power supply point and the fixed infinite power supply point in the exploration area are powered. And the potential difference of the corresponding frequency relative to the phase difference of the supply current of the same frequency ;

[0033] In the case of a two-pole device, when the mobile power supply point and the fixed infinite power supply point in the exploration area are used to measure the potential difference of different frequencies supplied by all measuring electrodes M and the corresponding power supply points on the fixed infinite measuring electrode And the potential difference of the corresponding frequency relative to the phase difference of the supply current of the same frequency .

[0034] Optionally, calculating the apparent resistivity based on the apparent resistivity parameter formula includes:

[0035] In the case where the electrode device adopts a quadrupole device, the formula is used. Calculate apparent resistivity parameters;

[0036] in, [1,p], , r4 is the number of mobile power supply points of the four-pole device; Indicates the number of a pair of mobile power supply points; For a pair of mobile power supply points The frequency value sent; According to a pair of mobile power supply points and the device coefficient for converting the coordinates of a pair of measuring electrodes M and N, For a pair of mobile power supply points Sent by Bi The potential difference measured on a pair of measuring electrodes M and N at the frequency value; For a pair of mobile power supply points Sent Current value at frequency value;

[0037] When the electrode device adopts a three-pole device, the formula is used. Calculate apparent resistivity parameters;

[0038] in, [1,p], , Number of mobile power supply points for three-pole installations; Indicates the number of the mobile power supply point; Mobile power supply point and the frequency value of the signal sent by the infinite power supply point; Mobile power supply point , device coefficient for coordinate conversion between the infinite power supply point and a pair of measuring electrodes M and N; Mobile power supply point and the infinitely distant power supply point The potential difference measured on a pair of measuring electrodes M and N at the frequency value; Mobile power supply point and the infinitely distant power supply point Current value at frequency value;

[0039] In the case where the electrode device adopts a two-pole device, the formula is used. Calculate apparent resistivity parameters;

[0040] In the formula [1,p], Number of mobile power supply points for two-pole installations; Indicates the number of the mobile power supply point; Mobile power supply point and the frequency value of the signal sent by the infinite power supply point; Mobile power supply point The device coefficient for converting the coordinates of a certain measuring electrode M; Mobile power supply point and the infinitely distant power supply point The potential difference measured between a certain measuring electrode M and an infinitely distant measuring electrode D at the frequency value; Mobile power supply point and the infinitely distant power supply point Current value at the frequency value.

[0041] Optionally, a dead zone time period is set between two adjacent frequencies sent by each channel. The dead zone time period means that the corresponding channel does not send a signal during this time period, and the length of the dead zone time period is not less than half the time length of the highest frequency signal between the two adjacent frequencies.

[0042] By adopting the above technical solution, in the frequency division method, when each channel sends a different frequency signal, the dead zone period can provide a buffer time for signal switching, ensuring that adjacent frequency signals can be clearly separated, thereby improving the purity of the signal; the existence of the dead zone period makes the sending and receiving process of each frequency signal more independent, avoiding data loss or distortion caused by too fast signal switching, thereby improving the accuracy of data acquisition.

[0043] Optionally, when each channel of the multi-channel frequency division multiplexing transmitter is powered through a certain power supply point, the current value of the same frequency is constant.

[0044] By adopting the above technical solution, the current value of the same frequency is constant, ensuring that the strength of the transmitted signal remains consistent throughout the power supply process, avoiding changes in the geoelectric response due to current fluctuations. This consistency significantly improves the reliability of the collected geoelectric information and reduces errors caused by current changes.

[0045] Optionally, the time synchronization error between the multi-channel frequency division electrical method transmitter and the multi-channel frequency division electrical method receiver is no more than 100 nanoseconds.

[0046] By adopting the above technical solution, the time synchronization error is controlled within 100 nanoseconds, ensuring that the multi-channel frequency division electrical receiver can accurately capture the start and end time of each frequency signal, avoid signal aliasing, and improve the accuracy of signal separation. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 It is a flow chart of an exploration method based on frequency division method of variable frequency signal in an embodiment of the present application.

[0048] Figure 2 This is a frequency conversion signal waveform diagram sent by a three-channel frequency division transmitter in this application.

[0049] Figure 3 This is a schematic diagram of the field deployment of the quadrupole device used in the embodiment of the present application.

[0050] Figure 4 This is a schematic diagram of the field arrangement of a three-pole device used in an embodiment of the present application.

[0051] Figure 5 This is a schematic diagram of the field arrangement of the diode device used in the embodiment of the present application. DETAILED DESCRIPTION

[0052] The present application is further described in detail below with reference to the accompanying drawings.

[0053] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

[0054] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0055] In this document, the term "and / or" simply describes a relationship between related objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A exists alone, A and B exist simultaneously, or B exists alone. Furthermore, the character " / " in this document, unless otherwise specified, generally indicates an "or" relationship between the related objects.

[0056] The embodiments of the present application are described in further detail below with reference to the accompanying drawings.

[0057] like Figure 1 As shown, a prospecting method based on frequency division electric method of variable frequency signal is described as follows (steps S101 to S109):

[0058] Step S101: determining a frequency value and a number of frequencies transmitted by each channel of a multi-channel frequency division electrical method transmitter based on an exploration objective and exploration requirements, wherein the number of frequencies is not less than the number of channels of the multi-channel frequency division electrical method transmitter, and the frequency value and the number of frequencies transmitted by each channel of the multi-channel frequency division electrical method transmitter are the same;

[0059] In this embodiment, the frequency value of each channel of the multi-channel frequency division method transmitter is determined according to the exploration purpose and exploration requirements. The number of channels of the multi-channel frequency division transmitter is q, where [1,p].

[0060] In this embodiment, a three-channel frequency division multiplexing transmitter is used as an example for description, wherein each channel transmits three single-frequency frequencies, which are 0.5 Hz, 1 Hz, and 2 Hz, respectively, that is, p=3. =0.5, =1, , the number of channels of the three-channel frequency division multiplexing transmitter is 3, that is, q=3.

[0061] like Figure 2 As shown, Figure 2 This is a waveform diagram of a frequency-varying signal sent by a three-channel frequency-division transmitter. In a multi-channel frequency-division transmitter, each channel sends the same frequency value and number of frequencies. Each channel sends three frequencies, with the frequency values ​​being 0.5 Hz, 1 Hz, and 2 Hz, respectively.

[0062] It is worth noting that the number of frequencies transmitted by the multi-channel frequency division multiplexing transmitter is an integer multiple of the number of channels of the multi-channel frequency division multiplexing transmitter, so as to ensure that the frequency values ​​of different channels are different at the same time.

[0063] In this embodiment, if Figure 2 As shown, the main explanation is that the number of frequencies is equal to the number of channels, that is, p=q=3.

[0064] Step S102, determining the number of mobile power supply points based on the electrode device of the resistivity profile method;

[0065] The electrode device includes a quadrupole device, a triode device and a biode device. The following describes step S102 using the quadrupole device, the triode device and the biode device respectively.

[0066] (1) Quadrupole device

[0067] When the electrode device adopts a quadrupole device, the number of mobile power supply points deployed in the exploration area shall not be less than twice the number of channels of the multi-channel frequency division power transmitter.

[0068] like Figure 3 As shown, Figure 3 is the number of mobile power supply points when using a three-channel frequency division power transmitter and a quadrupole device for exploration. The number of mobile power supply points is equal to 6=2*q=2*3=6, among which A1-A3 and B1-B3 are mobile power supply points, M and N are measuring electrodes, and M and N form a measuring electrode pair.

[0069] It should be noted that the number of mobile power supply points deployed in the exploration area is an integer multiple of the number of channels of the multi-channel frequency division power transmitter, and is not less than twice the number of channels of the multi-channel frequency division power transmitter.

[0070] (2) Three-pole device

[0071] When the electrode device adopts a three-pole device, in addition to the infinitely far power supply point, the number of mobile power supply points deployed in the exploration area shall not be less than the number of channels of the transmitter of the multi-channel frequency division method, and the number of mobile power supply points shall be an integer multiple of the number of channels of the transmitter of the multi-channel frequency division method.

[0072] like Figure 4 As shown, Figure 4 is the number of mobile power supply points when using a three-channel frequency division method transmitter and a three-pole device for exploration. The number of mobile power supply points is equal to 6=2*q=2*3>3, where A1-A6 are mobile power supply points, M and N are measuring electrode pairs, and C is the infinite power supply point.

[0073] It should be noted that the number of mobile power supply points deployed in the exploration area is an integer multiple of the number of channels of the multi-channel frequency division power transmitter.

[0074] (3) Diode device

[0075] When the electrode device adopts a two-pole device, in addition to the infinitely remote power supply point, the number of mobile power supply points deployed in the exploration area shall not be less than the number of channels of the transmitter of the multi-channel frequency division method, and the number of mobile power supply points shall be an integer multiple of the number of channels of the transmitter of the multi-channel frequency division method.

[0076] like Figure 5 As shown, Figure 5is the number of mobile power supply points when using a three-channel frequency division method transmitter and a two-pole device for exploration. The number of mobile power supply points is equal to 6=2*q=2*3>3, where A1-A6 are mobile power supply points, M is the measuring electrode, and C is the infinite power supply point.

[0077] It should be noted that the number of mobile power supply points deployed in the exploration area is an integer multiple of the number of channels of the multi-channel frequency division power transmitter.

[0078] Step S103, using each channel of the multi-channel frequency division multiplexing transmitter to send a variable frequency signal underground;

[0079] Among them, the characteristics of the frequency conversion signal sent by each channel of the multi-channel frequency division multiplexing transmitter meet the following requirements: each channel only sends one of the selected transmission frequencies at a certain moment; the frequency values ​​of the frequency conversion signals sent by each channel are different at the same moment; the transmission time length of a certain frequency in the frequency conversion signal sent by each channel is an integer multiple of one cycle of the frequency; the frequency conversion signal sent by each channel contains all the selected frequencies.

[0080] In this embodiment, each channel transmits only one of the selected transmission frequencies at a certain moment to meet the simple requirement of powering each channel; the frequency values ​​of the variable frequency signals transmitted by each channel are different at the same moment to prevent different channels from interfering with each other; the transmission time length of a certain frequency in the variable frequency signals transmitted by each channel is an integer multiple of one cycle of the frequency to obtain data with higher accuracy; the variable frequency signals transmitted by each channel include all the selected frequencies to ensure that each group of power supply points has data of all frequencies, thereby achieving detailed exploration.

[0081] In this embodiment, a three-channel frequency division multiplexing transmitter sending a variable frequency signal underground is taken as an example for description.

[0082] like Figure 2 As shown, each channel sends only one frequency among 0.5 Hz, 1 Hz and 2 Hz at each moment; and the frequencies at the same moment are different; the transmission time length of each frequency is 4 seconds, which is an integer multiple of the cycles of 0.5 Hz, 1 Hz and 2 Hz signals; the frequency conversion signal sent by each channel contains 0.5 Hz, 1 Hz and 2 Hz signals.

[0083] In this embodiment, each channel sends variable frequency signals of multiple frequencies, and the frequency transmission time length is an integer multiple of the period, so that the geoelectric responses at different frequencies can be completely collected, thereby improving the integrity of the collected data; each channel sends only one of the selected frequencies at the same time, and the frequency values ​​of each channel at the same time are different, which effectively avoids signal interference problems, thereby improving the accuracy of data collection; by selecting variable frequency signals of multiple frequencies to cover a wider frequency range, the resistivity and phase information of the underground medium at different frequencies can be obtained, thereby achieving a comprehensive characterization of complex geological structures.

[0084] Among them, the frequency ratio between the frequencies sent by each channel of the multi-channel frequency division method transmitter is greater than 1, thereby reducing the possibility of signal overlap and distinguishing geoelectric responses of different frequencies.

[0085] Preferably, the ratio between adjacent frequencies is greater than 1.5.

[0086] In this embodiment, a dead zone period is set between two adjacent frequencies sent by each channel. The dead zone period means that the corresponding channel does not send a signal during this period. The length of the dead zone period is not less than the time length of half a cycle of the highest frequency signal between the two adjacent frequencies. Among them, the dead zone periods between all adjacent frequencies are set to the same time length, such as selecting the time length of half a cycle of the highest frequency among all frequency signals (or some other fixed time length). Different time lengths can also be set, and there is no specific limitation on this.

[0087] In this embodiment, if Figure 2 As shown, the length of the dead zone period between adjacent frequencies of each channel is 0.125s.

[0088] Step S104, obtaining the current value of each frequency in the frequency conversion signal transmitted by each channel of the multi-channel frequency division current transmitter at the mobile power supply point;

[0089] The electrode device includes a quadrupole device, a triode device and a biode device. The following describes step S104 for the quadrupole device, the triode device and the biode device respectively.

[0090] (1) Quadrupole device

[0091] Specifically, when the electrode device adopts a quadrupole device, each channel of the multi-channel frequency division method transmitter is obtained at each pair of mobile power supply points. The current value of each frequency sent , Indicates the number of a pair of mobile power supply points, , r4 is the number of mobile power supply points of the four-pole device, For a pair of mobile power supply points The frequency value sent; where [1,p], where p is the total number of frequencies transmitted by each channel of the multi-channel frequency division multiplexing transmitter.

[0092] like Figure 2 and Figure 3 As shown, when a four-pole device and a three-channel frequency division method transmitter are used for exploration, the current value of each frequency transmitted by each channel of the three-channel frequency division method transmitter to A1B1, A2B2, and A3B3 at each mobile power supply point is obtained. ;in, Indicates the number of a mobile power supply point. A1B1, A2B2, A3B3 are mobile power supply point pairs A1B1, A2B2, A3B3. The frequency value sent by a mobile power supply point, such as Figure 2 0.5, 1, and 2 Hz are shown; where [1, p]; p is the total number of frequencies sent by each channel of the multi-channel frequency division multiplexing transmitter, and the total number of frequencies is 3.

[0093] (2) Three-pole device

[0094] Specifically, when the electrode device adopts a three-pole device, the current value of each frequency sent by each channel of the multi-channel frequency division method transmitter at each mobile power supply point and infinite power supply point is obtained. , Indicates the number of a mobile power supply point. , Number of mobile power supply points for three-pole installations, For a mobile power supply point The frequency value sent by the fixed infinite power supply point; [1,p]; p is the total number of frequencies transmitted by each channel of the multi-channel frequency division multiplexing transmitter.

[0095] like Figure 2 and Figure 4 As shown, when a three-pole device and a three-channel frequency division method transmitter are used for exploration, the current value of each frequency transmitted by each channel of the three-channel frequency division method transmitter at each mobile power supply point A1 to A6 and the infinite power supply point C is obtained. ;in, Indicates the number of a mobile power supply point, mobile power supply points A1 to A6; The frequency value sent by a mobile power supply point and a fixed infinite power supply point C, such as Figure 2 0.5, 1, and 2 Hz are shown; where [1, p]; p is the total number of frequencies sent by each channel of the multi-channel frequency division multiplexing transmitter, and the total number of frequencies is 3.

[0096] (3) Diode device

[0097] Specifically, when the electrode device adopts a two-pole device, the current value of each frequency sent by each channel of the multi-channel frequency division method transmitter at each mobile power supply point and infinite power supply point is obtained. , Indicates the number of a mobile power supply point. , Number of mobile power supply points for two-pole devices, For a mobile power supply point The frequency value sent by the fixed infinite power supply point; [1,p]; p is the total number of frequencies transmitted by each channel of the multi-channel frequency division multiplexing transmitter.

[0098] like Figure 2 and Figure 5 As shown, when a two-pole device and a three-channel frequency division method transmitter are used for exploration, the current value of each frequency transmitted by each channel of the three-channel frequency division method transmitter at each mobile power supply point A1 to A6 and the infinite power supply point C is obtained. ;in, Indicates the number of a mobile power supply point, mobile power supply points A1 to A6; The frequency value sent by a mobile power supply point and a fixed infinite power supply point C, such as Figure 2 0.5, 1, and 2 Hz are shown; where [1, p]; p is the total number of frequencies sent by each channel of the multi-channel frequency division multiplexing transmitter, and the total number of frequencies is 3.

[0099] It should be noted that when each channel of a multi-channel frequency division electrical prospecting transmitter is powered by a mobile power supply point, the current value at the same frequency remains constant. A power supply point in conventional electrical prospecting refers to a point close to the measuring point that generates a significant potential difference signal at the measuring point. An infinitely distant power supply point, on the other hand, refers to a fixed power supply point that is far from the measuring point and generates a negligible potential difference signal at the measuring point. In this embodiment, to avoid confusion, the power supply point in conventional electrical prospecting is named a mobile power supply point to distinguish it from the infinitely distant power supply point. Both mobile power supply points and infinitely distant power supply points are collectively referred to as power supply points.

[0100] Step S105, obtaining the potential differences of different frequencies measured on the measuring electrode pair by a multi-channel frequency division method receiver synchronized with the multi-channel frequency division method transmitter in time, and the phase difference of the potential differences of the corresponding frequencies relative to the supply current of the same frequency;

[0101] In this embodiment, before using the multi-channel frequency division electrical method receiver, the multi-channel frequency division electrical method receiver and the multi-channel frequency division electrical method transmitter need to be synchronized in time to achieve correlation processing between the supply current and the potential difference.

[0102] In this embodiment, the three-channel frequency division method transmitter records the start and end time corresponding to each frequency transmitted by each channel; the three-channel frequency division method receiver records the start and end time corresponding to each frequency received by each channel; the start and end times of the three-channel frequency division method transmitter and the three-channel frequency division method receiver determine that a signal of a certain frequency at a certain moment comes from the corresponding mobile power supply point; Figure 2 As shown, the frequency values ​​sent in the first, second and third channels from 0 to 4s are 0.5, 1 and 2 Hz respectively; the frequency values ​​sent in the first, second and third channels from 4 to 8s are 1, 2 and 0.5 Hz respectively; the three-channel frequency division receiver identifies the power supply point from which a certain frequency at a certain moment comes according to the frequency start and end time of the three-channel frequency division transmitter.

[0103] It should be noted that the time synchronization error between the multi-channel frequency division electrical method transmitter and the multi-channel frequency division electrical method receiver is no more than 100 nanoseconds.

[0104] In the multi-channel frequency division method, the signals sent by different channels have different frequencies, and the signal switching time interval is short (such as the dead zone period). If the time synchronization error is large, the receiver may not be able to accurately identify and separate signals of different frequencies, thereby causing signal aliasing problems. Controlling the time synchronization error within 100 nanoseconds ensures that the receiver can accurately capture the start and end times of each frequency signal, avoids signal aliasing, and improves the accuracy of signal separation. For high-frequency signals, such as tens of kHz or higher, their cycle time is very short. For example, the cycle of a 10kHz signal is 100 microseconds. The time synchronization error is less than 100 nanoseconds, which only accounts for one thousandth of the cycle, and has almost no impact on the acquisition of high-frequency signals, thereby supporting wide-band detection tasks.

[0105] The electrode device includes a quadrupole device, a triode device and a biode device. The following describes step S105 using the quadrupole device, the triode device and the biode device respectively.

[0106] (1) Quadrupole device

[0107] The specific requirements for testing the potential in a quadrupole device are as follows: When the electrode device is a quadrupole device, a multi-channel frequency division method receiver is used to measure the potential of different frequencies on the measuring electrode M and the measuring electrode N, where the measuring electrode M and the measuring electrode N form a measuring electrode pair. The measurement time on each pair of measuring electrodes shall not be less than the total time length of all frequencies transmitted by the multi-channel frequency division method transmitter;

[0108] The total time length for each channel of the multi-channel frequency division method transmitter to transmit all frequencies is 12s, so the measurement time on each pair of measuring electrodes is not less than 12s.

[0109] In the case of using a quadrupole device for exploration, the implementation of step S105 is specifically as follows: measuring the potential difference of different frequencies supplied by all measuring electrodes M and the corresponding mobile power supply points on the measuring electrode N when the mobile power supply point in the exploration area supplies power. And the potential difference of the corresponding frequency relative to the phase difference of the supply current of the same frequency .

[0110] like Figure 3 As shown, in this embodiment, each pair of mobile power supply points in the survey area is measured. When power is supplied, the potential difference of different frequencies supplied by the corresponding power supply points on the measuring electrode M and the measuring electrode N is The potential difference of the corresponding frequency and the phase difference of the supply current of the same frequency .

[0111] (2) Three-pole device

[0112] The specific requirements for the potential test in the three-pole device are as follows: when the electrode device adopts a three-pole device, a multi-channel frequency division electrical method receiver is used to measure the potential of different frequencies on the measuring electrode M and the measuring electrode N, where the measuring electrode M and the measuring electrode N form a measuring electrode pair, and the measurement time on each pair of measuring electrodes is not less than the total time length of all frequencies sent by the multi-channel frequency division electrical method transmitter.

[0113] In this embodiment, the total time length for each channel of the three-channel frequency division multiplexing transmitter to transmit all frequencies is 12 seconds, so the measurement time for each measuring electrode pair is no less than 12 seconds.

[0114] In the case of using a three-pole device for exploration, the implementation of step S105 is specifically as follows: when the mobile power supply point and the fixed infinite power supply point in the exploration area are powered, the potential difference of different frequencies supplied by all the measuring electrodes M and the corresponding power supply points on the measuring electrode N is measured. And the potential difference of the corresponding frequency relative to the phase difference of the supply current of the same frequency .

[0115] like Figure 4 As shown, in this embodiment, when the mobile power supply point in the exploration area and the fixed infinite power supply point C are powered, the potential difference of different frequencies supplied by the corresponding power supply points on the measuring electrode M and the measuring electrode N is And the potential difference of the corresponding frequency relative to the phase difference of the supply current of the same frequency

[0116] By using the start and end times of all frequencies recorded by the time-synchronized multi-channel frequency division method transmitter and the multi-channel frequency division method receiver, it is possible to identify which mobile power supply point a certain frequency at a certain moment comes from.

[0117] (3) Diode device

[0118] The specific requirements for testing the potential in a two-pole device are as follows: When the electrode device adopts a two-pole device, a multi-channel frequency division electrical method receiver is used to measure the potential of different frequencies on a certain measuring electrode M and a fixed infinite measuring electrode, where the measuring electrode M and the infinite measuring electrode form a measuring electrode pair, and the measurement time on each pair of measuring electrodes is not less than the total time length of all frequencies sent by the multi-channel frequency division electrical method transmitter.

[0119] In the case of using a two-pole device for exploration, the implementation of step S105 is specifically as follows: when the mobile power supply point and the fixed infinite power supply point in the exploration area are powered, the potential difference of different frequencies supplied by all measuring electrodes M and the corresponding power supply points on the fixed infinite measuring electrode is measured. And the potential difference of the corresponding frequency relative to the phase difference of the supply current of the same frequency .

[0120] like Figure 5 As shown, in this embodiment, when the mobile power supply point in the exploration area and the fixed infinite power supply point C are powered, the potential difference of different frequencies supplied by the corresponding power supply points on the measuring electrode M and the measuring electrode N is And the potential difference of the corresponding frequency relative to the phase difference of the supply current of the same frequency .

[0121] Step S106, measuring the coordinates of all measurement electrode pairs and all mobile power supply points, and determining device coefficients for coordinate conversion based on the coordinates;

[0122] In this embodiment, in order to facilitate the calculation of subsequent device coefficients, the coordinates of all measuring electrodes and all power supply points adopt the geodetic kilometer grid coordinate system; the existing algorithm is used to determine the device coefficient for coordinate conversion based on the tested coordinates, such as the device coefficient formula of the conductive electrical method is used to calculate the device coefficient based on the coordinates of the power supply point and the measuring electrode.

[0123] Step S107, obtaining the apparent resistivity parameter formula corresponding to the electrode device;

[0124] Step S108, calculating the apparent resistivity based on the apparent resistivity parameter formula;

[0125] The electrode device includes a quadrupole device, a triode device and a bipolar device, and each electrode device has a corresponding calculation formula.

[0126] The following describes step S108 using a quadrupole device, a triplex device, and a doublex device, respectively.

[0127] (1) Quadrupole device

[0128] In the case where the electrode device adopts a quadrupole device, the formula is used. Calculate the apparent resistivity parameters; where, [1,p], , r4 is the number of mobile power supply points of the four-pole device; Indicates the number of a pair of mobile power supply points; For a pair of mobile power supply points The frequency value sent; According to a pair of mobile power supply points The device coefficient for converting the coordinates of a pair of measuring electrodes M and N For a pair of mobile power supply points Sent by Bi The potential difference measured on a pair of measuring electrodes M and N at the frequency value; For a pair of mobile power supply points Sent Current value at the frequency value.

[0129] (2) Three-pole device

[0130] When the electrode device adopts a three-pole device, the formula is used. Calculate the apparent resistivity parameters; where, [1,p], , Number of mobile power supply points for three-pole installations; Indicates the number of the mobile power supply point; Mobile power supply point and the frequency value of the signal sent by the infinite power supply point; Mobile power supply point , device coefficient for coordinate conversion between the infinite power supply point and a pair of measuring electrodes M and N; Mobile power supply point and the infinitely distant power supply point The potential difference measured on a pair of measuring electrodes M and N at the frequency value; Mobile power supply point and the infinitely distant power supply point Current value at the frequency value.

[0131] (3) Diode device

[0132] In the case where the electrode device adopts a two-pole device, the formula is used. Calculate the apparent resistivity parameters; where the formula [1,p], Number of mobile power supply points for two-pole installations; Indicates the number of the mobile power supply point; Mobile power supply point and the frequency value of the signal sent by the infinite power supply point; Mobile power supply point The device coefficient for converting the coordinates of a certain measuring electrode M; Mobile power supply point and the infinitely distant power supply point The potential difference measured between a certain measuring electrode M and an infinitely distant measuring electrode D at the frequency value; Mobile power supply point and the infinitely distant power supply point Current value at the frequency value.

[0133] Step S109: Analyze the apparent resistivity and phase difference of all measuring electrodes at all frequencies to obtain detection and interpretation results.

[0134] In this embodiment, by analyzing the obtained apparent resistivity and phase difference, the resistivity distribution, layered structure or abnormal body location of the underground medium can be inferred, and the data analysis results can be converted into an intuitive geological model or report to provide support for subsequent decision-making.

[0135] The terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0136] The above description is merely a preferred embodiment of the present application and an illustration of the technical principles employed. Those skilled in the art should understand that the scope of application involved in this application is not limited to the technical solutions formed by a specific combination of the above-mentioned technical features, but should also cover other technical solutions formed by any combination of the above-mentioned technical features or their equivalents without departing from the aforementioned application concept. For example, a technical solution formed by replacing the above-mentioned features with (but not limited to) technical features with similar functions applied for in this application.

Claims

1. A prospecting method based on frequency division method of variable frequency signal, characterized in that: include: Determining, based on the exploration objectives and requirements, the frequency value and number of frequencies transmitted by each channel of the multi-channel frequency division electrical transmitter, wherein the number of frequencies is not less than the number of channels of the multi-channel frequency division electrical transmitter, and the frequency value and number of frequencies transmitted by each channel of the multi-channel frequency division electrical transmitter are the same; Determine the number of mobile power supply points using an electrode device based on the resistivity profile method; Utilizing each channel of the multi-channel frequency division electric method transmitter to transmit a variable frequency signal underground; Obtaining a current value of each frequency in the frequency conversion signal transmitted by each channel of the multi-channel frequency division current transmitter at the mobile power supply point; Acquire the potential differences of different frequencies measured on the measuring electrode pair by a multi-channel frequency division method receiver synchronized in time with the multi-channel frequency division method transmitter, and the phase difference of the potential differences of the corresponding frequencies relative to the supply current of the same frequency; measuring the coordinates of all measuring electrode pairs and all mobile power supply points, and determining device coefficients for coordinate conversion based on the coordinates; Obtaining a parameter formula for apparent resistivity corresponding to the electrode device; Calculating the apparent resistivity based on the apparent resistivity parameter formula; Analyze the apparent resistivity and phase difference of all measuring electrodes at all frequencies to obtain the exploration and interpretation results; The characteristics of the frequency conversion signal transmitted by each channel of the multi-channel frequency division multiplexing transmitter meet the following requirements: Each channel sends only one of the selected transmission frequencies at a certain moment; the frequency values ​​of the variable frequency signals sent by each channel are different at the same moment; the sending time length of a certain frequency in the variable frequency signals sent by each channel is an integer multiple of one cycle of the frequency; the variable frequency signals sent by each channel contain all the selected frequencies.

2. The method according to claim 1, characterized in that The electrode device includes one of a quadrupole device, a tripolar device, and a bipolar device. The method of determining the number of mobile power supply points using the electrode device based on the resistivity profile method includes: In the case of a quadrupole electrode device, the number of mobile power supply points deployed in the exploration area shall not be less than twice the number of channels of the multi-channel frequency division method transmitter; When the electrode device adopts a three-pole device or a two-pole device, in addition to the infinite power supply point, the number of mobile power supply points deployed in the exploration area shall not be less than the number of channels of the transmitter of the multi-channel frequency division method, and the number of mobile power supply points shall be an integer multiple of the number of channels of the transmitter of the multi-channel frequency division method.

3. The method according to claim 1, characterized in that The obtaining of the current value of each frequency transmitted by each channel of the multi-channel frequency division current transmitter at the mobile power supply point includes: In the case where the electrode device adopts a quadrupole device, each channel of the multi-channel frequency division method transmitter is obtained at each pair of mobile power supply points. The current value of each frequency sent , Indicates the number of a pair of mobile power supply points, , r4 is the number of mobile power supply points of the four-pole device, For a pair of mobile power supply points The frequency value sent; where [1, p], where p is the total number of frequencies transmitted by each channel of the multi-channel frequency division multiplexing transmitter; In the case where the electrode device adopts a three-pole device or a two-pole device, the current value of each frequency sent by each channel of the multi-channel frequency division method transmitter at each mobile power supply point and infinite power supply point is obtained. , Indicates the number of a mobile power supply point. , for, Number of mobile power supply points for two-pole devices, For a mobile power supply point The frequency value sent by the fixed infinite power supply point; [1, p]; p is the total number of frequencies transmitted by each channel of the multi-channel frequency division multiplexing transmitter.

4. The method according to claim 1, wherein Before obtaining the potential differences of different frequencies measured on the measuring electrode pair by the multi-channel frequency division method receiver synchronized with the multi-channel frequency division method transmitter, the method further includes: In the case where the electrode device adopts a four-pole device or a three-pole device, a multi-channel frequency division method receiver is used to measure the potential of different frequencies on the measuring electrode M and the measuring electrode N, wherein the measuring electrode M and the measuring electrode N constitute a measuring electrode pair, and the measurement time on each pair of measuring electrodes is not less than the total time length of all frequencies transmitted by the multi-channel frequency division method transmitter; In the case where the electrode device adopts a two-pole device, a multi-channel frequency division electrical method receiver is used to measure the potentials of different frequencies on a certain measuring electrode M and a fixed infinitely distant measuring electrode, wherein the measuring electrode M and the infinitely distant measuring electrode form a measuring electrode pair, and the measured time on each pair of measuring electrodes is not less than the total time length of all frequencies transmitted by the multi-channel frequency division electrical method transmitter.

5. The method according to claim 1, wherein The step of obtaining the potential differences of different frequencies measured on the measuring electrode pair by a multi-channel frequency division method receiver synchronized with the multi-channel frequency division method transmitter in time, and the phase difference of the potential differences of the corresponding frequencies relative to the supply current of the same frequency, comprises: When the electrode device adopts a quadrupole device, the potential difference of different frequencies supplied by the corresponding mobile power supply points on all measuring electrodes M and measuring electrode N is measured when the mobile power supply point in the exploration area supplies power. And the potential difference of the corresponding frequency relative to the phase difference of the supply current of the same frequency ; When the electrode device adopts a three-pole device, the potential difference of different frequencies supplied by the corresponding power supply points on all measuring electrodes M and measuring electrodes N is measured when the mobile power supply point and the fixed infinite power supply point in the exploration area are powered. And the potential difference of the corresponding frequency relative to the phase difference of the supply current of the same frequency ; In the case of a two-pole device, when the mobile power supply point and the fixed infinite power supply point in the exploration area are used to measure the potential difference of different frequencies supplied by all measuring electrodes M and the corresponding power supply points on the fixed infinite measuring electrode And the potential difference of the corresponding frequency relative to the phase difference of the supply current of the same frequency .

6. The method according to claim 1, characterized in that The calculating the apparent resistivity based on the apparent resistivity parameter formula includes: In the case where the electrode device adopts a quadrupole device, the formula is used. Calculate apparent resistivity parameters; in, [1,p], , r4 is the number of mobile power supply points of the four-pole device; Indicates the number of a pair of mobile power supply points; For a pair of mobile power supply points The frequency value sent; According to a pair of mobile power supply points The device coefficient for converting the coordinates of a pair of measuring electrodes M and N; For a pair of mobile power supply points Sent by Bi The potential difference measured on a pair of measuring electrodes M and N at the frequency value; For a pair of mobile power supply points Sent Current value at frequency value; When the electrode device adopts a three-pole device, the formula is used. Calculate apparent resistivity parameters; in, [1,p], , Number of mobile power supply points for three-pole installations; Indicates the number of the mobile power supply point; Mobile power supply point and the frequency value of the signal sent by the infinite power supply point; Mobile power supply point , device coefficient for coordinate conversion between the infinite power supply point and a pair of measuring electrodes M and N; Mobile power supply point and the infinitely distant power supply point The potential difference measured on a pair of measuring electrodes M and N at the frequency value; Mobile power supply point and the infinitely distant power supply point Current value at frequency value; In the case where the electrode device adopts a two-pole device, the formula is used. Calculate apparent resistivity parameters; In the formula [1,p], Number of mobile power supply points for two-pole installations; Indicates the number of the mobile power supply point; Mobile power supply point and the frequency value of the signal sent by the infinite power supply point; Mobile power supply point The device coefficient for converting the coordinates of a certain measuring electrode M; Mobile power supply point and the infinitely distant power supply point The potential difference measured between a certain measuring electrode M and an infinitely distant measuring electrode D at the frequency value; Mobile power supply point and the infinitely distant power supply point Current value at the frequency value.

7. The method according to claim 1, characterized in that The frequency ratio between the frequencies transmitted by each channel of the multi-channel frequency division multiplexing transmitter is greater than 1.

8. The method according to claim 1, characterized in that A dead zone period is set between two adjacent frequencies sent by each channel. The dead zone period means that the corresponding channel does not send a signal during this period, and the length of the dead zone period is not less than half the time length of the highest frequency signal between the two adjacent frequencies.

9. The method according to claim 1, characterized in that When each channel of the multi-channel frequency division power transmitter is powered through a certain power supply point, the current value of the same frequency is constant.

10. The method according to claim 1, characterized in that The time synchronization error between the multi-channel frequency division electrical method transmitter and the multi-channel frequency division electrical method receiver is no more than 100 nanoseconds.

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