A frequency-division electrical method based on variable frequency signal

Abstract

The application relates to an exploration method based on frequency division electrical method of variable frequency signals and belongs to the technical field of electrical exploration, which comprises the following steps: determining the frequency value and the frequency quantity of each channel of a multi-channel frequency division electrical method transmitter based on an exploration purpose and exploration requirements; transmitting variable frequency signals to the underground by each channel of the multi-channel frequency division electrical method transmitter; obtaining the current value of each frequency transmitted by each channel of the multi-channel frequency division electrical method transmitter at a mobile power supply point; obtaining the potential difference of different frequencies measured by a multi-channel frequency division electrical method receiver at a measuring electrode pair and the phase difference of the potential difference of the corresponding frequency relative to the current of the same frequency power supply; determining the device coefficient based on the coordinates of the measuring electrode pair and all the mobile power supply points; calculating the apparent resistivity based on the apparent resistivity parameter formula corresponding to the electrode device; and obtaining the exploration interpretation result based on the apparent resistivity and the phase difference. The application has the effect of comprehensively and accurately collecting geoelectric information.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrical prospecting, in particular to a frequency division electrical prospecting method based on variable frequency signals. BACKGROUND

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

[0003] Among many electrical prospecting technologies, the frequency division electrical prospecting method with single frequency signal stands out with its unique advantages. This technology transmits single frequency power supply current signals to each channel through the transmitter, and the current signal frequencies of different channels are different. In terms of data identification, the receiving device can accurately identify the electrical signal data collected by each channel according to the frequency characteristics preset by different channels, so as to distinguish the response information under different positions or different geological conditions. In terms of data representation, the collected electrical signal data will be stored and transmitted in a specific digital coding form. Compared with traditional methods, the frequency division electrical prospecting method with single frequency signal has shown significant results in improving exploration effect, reducing cost and accelerating exploration process.

[0004] Although the frequency division electrical prospecting method with single frequency signal has many advantages when the same frequency current value of the single frequency signal is constant when the multi-channel frequency division electrical prospecting transmitter supplies power through a power supply point, it also has limitations, especially in exploration accuracy, which makes it difficult to achieve the best results when facing exploration tasks that require higher accuracy and more detailed information. Therefore, how to break through the limitations of single frequency signals while maintaining exploration efficiency and achieving comprehensive and accurate collection of geoelectric information has become a key problem to be solved in the field of electrical prospecting. SUMMARY

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

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

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

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

[0009] Use each channel of the multi-channel frequency division electrical prospecting transmitter to transmit variable frequency signals to the underground.

[0010] obtaining current values of each frequency in the variable frequency signal transmitted by each channel of the multi-channel frequency division electrical method transmitter at the mobile power supply point;

[0011] obtaining potential differences of different frequencies measured by a multi-channel frequency division electrical method receiver synchronized in time with the multi-channel frequency division electrical method transmitter at a pair of measuring electrodes and phase differences of the potential differences of the corresponding frequencies relative to the current of the same frequency power supply;

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

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

[0014] calculating an apparent resistivity based on the apparent resistivity parameter formula;

[0015] analyzing the apparent resistivities and phase differences of all frequencies of all measuring electrodes to obtain interpretation results;

[0016] The characteristics of the variable frequency signal transmitted by each channel of the multi-channel frequency division electrical method transmitter satisfy:

[0017] each channel only transmits one of the selected transmission frequencies at a time; the frequency values of the variable frequency signals transmitted by each channel at the same time are all different; the transmission time length of a certain frequency in the variable frequency signal transmitted by each channel is an integer multiple of the period of the frequency; and the variable frequency signal transmitted by each channel contains all the selected frequencies.

[0018] By using the above technical solution, the variable frequency signal transmitted 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 under different frequencies can be completely collected; since each channel only transmits one of the selected frequencies at the same time, and the frequency values of the channels at the same time are all different, the problem of signal interference can be reduced, thereby improving the accuracy of data collection; the frequency values in each channel at the same time are different, and each channel will pass through all the frequency values, so that different frequency results can be obtained at the same measuring point, and fine exploration can be realized; by selecting multiple frequencies, a wider frequency range can be covered, so that the resistivity and phase information of the underground medium under different frequencies can be obtained, and a comprehensive description of complex geological structures can be realized.

[0019] Optionally, the electrode device includes one of a four-pole device, a three-pole device, and a two-pole device, and the electrode device based on the resistivity profile method determines the number of mobile power supply points, including:

[0020] In the case of using a four-pole device as the electrode device, the number of the mobile power supply points arranged in the exploration area is not less than 2 times the number of the channels of the multi-channel frequency division electrical method transmitter;

[0021] In the case of using a three-pole device or a two-pole device as the electrode device, in addition to the infinite power supply point, the number of the mobile power supply points arranged in the exploration area is not less than the number of the channels of the multi-channel frequency division electrical method transmitter, and the number of the mobile power supply points is an integer multiple of the number of the channels of the multi-channel frequency division electrical method transmitter.

[0022] By using the above technical solutions, in the case of using a four-pole device, the number of the mobile power supply points is not less than 2 times the number of the channels of the multi-channel frequency division electrical method transmitter, so that the power supply points connected by each channel are all different, a more intensive power supply point distribution can be obtained, and the sampling density of the underground medium in the exploration area is improved; in the case of using a three-pole device or a two-pole device, the number of the mobile power supply points is not less than the number of the channels of the multi-channel frequency division electrical method transmitter, so that the data coverage is ensured, unnecessary redundant measurement is reduced, and the operation efficiency is improved; by reasonably configuring the number of the mobile power supply points, each channel simultaneously transmits signals at different power supply points, the advantages of the multi-channel frequency division electrical method are fully utilized, the data acquisition time is significantly shortened, the minimum number of power supply points is set according to the type of the electrode device, too much redundant measurement is avoided, the integrity of the data is ensured, and the overall operation efficiency is improved.

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

[0024] In the case of using a four-pole device as the electrode device, the current value of each frequency transmitted by each channel of the multi-channel frequency division electrical method transmitter at each pair of mobile power supply points is obtained. , wherein i represents the number of a certain pair of mobile power supply points, r4 is the number of the mobile power supply points of the four-pole device, is the frequency value transmitted by a certain pair of mobile power supply points ; wherein [1,p] and p is the total number of the frequencies transmitted by each channel of the multi-channel frequency division electrical method transmitter.

[0025] In the case of using a three-pole device or a two-pole device as the electrode device, the current value of each frequency transmitted by each channel of the multi-channel frequency division electrical method transmitter at each mobile power supply point and the infinite power supply point is obtained. , wherein i represents the number of a certain mobile power supply point, , r3 is the number of the mobile power supply points of the three-pole device, the number of mobile power supply points for the dipole device, a certain mobile power supply point the frequency value sent by the fixed infinite power supply point; wherein [1, p]; p is the total number of frequencies sent by each channel of the multi-channel frequency division electrical method transmitter.

[0026] Optionally, before measuring the potential difference of different frequencies measured by the multi-channel frequency division electrical method receiver synchronized in time with the multi-channel frequency division electrical method transmitter on the measuring electrode pair, the multi-channel frequency division electrical method receiver further comprises:

[0027] In the case of a four-pole device or a three-pole device, the multi-channel frequency division electrical method receiver measures the potential of different frequencies on measuring electrode M and measuring electrode N, where measuring electrode M and measuring electrode N form a measuring electrode pair, and the measuring time on each measuring electrode pair is not less than the total time length of all frequencies sent by the multi-channel frequency division electrical method transmitter.

[0028] In the case of a two-pole device, the multi-channel frequency division electrical method receiver measures the potential of different frequencies on a certain measuring electrode M and a fixed infinite measuring electrode, where measuring electrode M and the infinite measuring electrode form a measuring electrode pair, and the measuring time on each measuring electrode pair is not less than the total time length of all frequencies sent by the multi-channel frequency division electrical method transmitter.

[0029] By using the above technical solution, the measuring time on each measuring electrode pair is not less than the total time length of all frequencies sent by the multi-channel frequency division electrical method transmitter, and the measurement results of all frequencies can be obtained, avoiding data loss caused by insufficient measuring time.

[0030] Optionally, the multi-channel frequency division electrical method receiver synchronized in time with the multi-channel frequency division electrical method transmitter measures the potential difference of different frequencies on the measuring electrode pair and the phase difference of the potential difference of the corresponding frequency with respect to the same frequency power supply current, comprising:

[0031] In the case of a four-pole device, the multi-channel frequency division electrical method receiver measures the potential difference of different frequencies on all measuring electrodes M and measuring electrodes N supplied by the corresponding mobile power supply points in the exploration area and the phase difference of the potential difference of the corresponding frequency with respect to the same frequency power supply current ;

[0032] In the case of a three-pole device, the multi-channel frequency division electrical method receiver measures the potential difference of different frequencies on all measuring electrodes M and measuring electrodes N supplied by the corresponding mobile power supply points in the exploration area and the phase difference of the potential difference of the corresponding frequency with respect to the same frequency power supply current ;

[0033] In the case of the electrode device employing a two-pole device, the potential difference of different frequencies supplied by all the measuring electrodes M and the corresponding supply point on the fixed infinite measuring electrode when the survey area is powered by the moving supply point and the fixed infinite supply point and the phase difference of the potential difference of the corresponding frequency with respect to the supply current of the same frequency .

[0034] Optionally, the apparent resistivity is calculated based on the apparent resistivity parameter formula, comprising:

[0035] In the case of the electrode device employing a four-pole device, the apparent resistivity parameter is calculated by the formula .

[0036] wherein, [1,p], , and r4 is the number of moving supply points of the four-pole device; denotes the number of a certain pair of moving supply points; is the frequency value sent by a certain pair of moving supply points ; is the device coefficient calculated according to the coordinates of a certain pair of moving supply points and a certain pair of measuring electrodes M and N; is the potential difference measured on a certain pair of measuring electrodes M and N when a certain pair of moving supply points Bi sends the frequency value ; is the current value when a certain pair of moving supply points sends the frequency value ;

[0037] In the case of the electrode device employing a three-pole device, the apparent resistivity parameter is calculated by the formula .

[0038] wherein, [1,p], , is the number of moving supply points of the three-pole device; denotes the number of a moving supply point; is the frequency value sent by the moving supply point and the infinite supply point; is the device coefficient calculated according to the coordinates of the moving supply point , the infinite supply point and a certain pair of measuring electrodes M and N; is the potential difference measured on a certain pair of measuring electrodes M and N when the moving supply point and the infinite supply point send the frequency value ; Mobile power supply point and the frequency value of the signal sent by the infinite power supply point the current value at the frequency value;

[0039] In the case of using a two-pole device for the electrode device, the apparent resistivity parameter is calculated using the formula

[0040] wherein in the formula [1, p], is the number of mobile power supply points of the two-pole device; denotes the number of the mobile power supply point; is the mobile power supply point and the frequency value of the signal sent by the infinite power supply point is the device coefficient converted according to the coordinates of the mobile power supply point and a certain measurement electrode M; is the mobile power supply point and the frequency value of the signal sent by the infinite power supply point the potential difference measured on a certain measurement electrode M and the infinite measurement electrode D at the frequency value; is the mobile power supply point and the frequency value of the signal sent by the infinite power supply point the current value at the frequency value.

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

[0042] By using the above technical solution, in the frequency division electrical method, when each channel sends a signal of different frequency, the dead time period can provide a buffer time for signal switching, ensuring that the adjacent frequency signals can be clearly separated, and the purity of the signal is improved; the existence of the dead time period makes the transmission and reception 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 electrical method transmitter is powered through a certain power supply point, the current value of the same frequency is constant.

[0044] By using the above technical solution, the current value of the same frequency is constant, ensuring that the intensity of the transmitted signal remains consistent throughout the power supply process, avoiding changes in the geoelectric response caused by current fluctuations, and this consistency significantly improves the reliability of the collected geoelectric information, reducing 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 not greater than 100 nanoseconds.

[0046] By adopting the above technical solution, the time synchronization error is controlled within 100 nanoseconds, and it is ensured that the multi-channel frequency division electrical method 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 DRAWINGS

[0047] Figure 1 is a flowchart of an exploration method based on a variable frequency signal frequency division electrical method in the embodiments of the present application.

[0048] Figure 2 is a variable frequency signal waveform diagram sent by a three-channel frequency division electrical method transmitter in the present application.

[0049] Figure 3 is a schematic diagram of field arrangement of a four-pole device in the embodiments of the present application.

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

[0051] Figure 5 is a schematic diagram of field arrangement of a two-pole device in the embodiments of the present application. DETAILED DESCRIPTION

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

[0053] The present embodiments are merely explanatory of the present application, and are not a limitation of the present application, and those skilled in the art can make modifications to the present embodiments without creative contribution, as long as the modifications are within the scope of the claims of the present application.

[0054] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are some of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative contribution are within the scope of protection of the present application.

[0055] In addition, the term "and / or" in this paper is merely to describe the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which can represent the three cases of A alone, A and B together, and B alone. In addition, the character " / " in this paper generally represents an "or" relationship between the associated objects unless otherwise specified.

[0056] The embodiments of this application will now be described in further detail with reference to the accompanying drawings.

[0057] like Figure 1 As shown, an exploration method based on frequency division multiplexing (FDM) using frequency conversion signals is described in the following main process flow (steps S101-S109):

[0058] Step S101: Based on the exploration purpose and exploration requirements, determine the frequency value and number of frequencies transmitted by each channel of the multi-channel frequency division multiplexing transmitter. The number of frequencies shall not be less than the number of channels of the multi-channel frequency division multiplexing transmitter, and the frequency value and number of frequencies transmitted by each channel of the multi-channel frequency division multiplexing transmitter shall be the same.

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

[0060] In this embodiment, a three-channel frequency division multiplexing transmitter is used as an example. Each channel transmits three single-frequency signals with values ​​of 0.5 Hz, 1 Hz, and 2 Hz, i.e., p=3. =0.5, =1, The number of channels in a three-channel frequency division multiplexing transmitter is 3, i.e., q=3.

[0061] like Figure 2 As shown, Figure 2 The waveform diagram shows a frequency conversion signal transmitted by a three-channel frequency division multiplexing transmitter. In the multi-channel frequency division multiplexing transmitter, each channel transmits the same frequency value and the same number of frequencies. Each channel transmits 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 multiplexer is an integer multiple of the number of channels of the multi-channel frequency division multiplexer, so as to ensure that the frequency values ​​of different channels are different at the same time.

[0063] In this embodiment, as Figure 2 As shown, the explanation mainly uses the principle that the number of frequencies equals the number of channels, i.e., p=q=3.

[0064] Step S102: Determine the number of moving power supply points based on the electrode device using the resistivity profile method;

[0065] The electrode device includes a quadrupole device, a triode device, and a diode device. Step S102 will be described below using the quadrupole device, triode device, and diode device respectively.

[0066] (a) Four-pole device

[0067] When a four-electrode device is used as the 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 transmitter.

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

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

[0070] (ii) Three-electrode device

[0071] When a three-electrode device is used as the electrode device, in addition to the infinity 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 The number of mobile power supply points is given when using a three-channel frequency division electric method transmitter and a three-electrode 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 power supply point at infinity.

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

[0074] (III) Diode Device

[0075] When the electrode device adopts a two-electrode 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.

[0076] like Figure 5 As shown, Figure 5The number of mobile power supply points is given when using a three-channel frequency division power method transmitter and a diode 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 power supply point at infinity.

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

[0078] Step S103: Use each channel of the multi-channel frequency division transmitter to send a frequency conversion signal underground;

[0079] The characteristics of the frequency-converted signal transmitted by each channel of the multi-channel frequency division multiplexing transmitter are as follows: each channel transmits only one of the selected transmission frequencies at a certain moment; the frequency values ​​of the frequency-converted signals transmitted by each channel are different at the same moment; the transmission time of a certain frequency in the frequency-converted signal transmitted by each channel is an integer multiple of one cycle of that frequency; and the frequency-converted signal transmitted by each channel contains all frequencies of the selected frequency.

[0080] In this embodiment, each channel transmits only one of the selected transmission frequencies at a given time to meet the simple requirement of powering each channel; the frequency values ​​of the frequency-converted signals transmitted by each channel are different at the same time to prevent interference between different channels; the transmission time of a certain frequency in the frequency-converted signals transmitted by each channel is an integer multiple of one cycle of that frequency to obtain more accurate data; and the frequency-converted signals transmitted by each channel include all frequencies of the selected frequency to ensure that each power supply point has data of all frequencies, enabling detailed exploration.

[0081] In this embodiment, the transmission of frequency-converted signals to the ground by a three-channel frequency division transmitter is used as an example for illustration.

[0082] like Figure 2 As shown, each channel transmits only one of the frequencies of 0.5 Hz, 1 Hz, and 2 Hz at each time; and the frequencies at the same time are all different; the transmission time of each frequency is 4 seconds, which are all integer multiples of the period of the 0.5 Hz, 1 Hz, and 2 Hz signals; the frequency conversion signal transmitted by each channel contains 0.5 Hz, 1 Hz, and 2 Hz signals.

[0083] In the embodiment, each channel transmits a plurality of frequency signals, and the transmission time length of the frequency is an integer multiple of the period, so that the geoelectric response at different frequencies can be completely collected, and the completeness of the collected data is improved; each channel only transmits one of the selected frequencies at the same time, and the frequency values of the channels at the same time are all different, which effectively avoids the problem of signal interference, thereby improving the accuracy of data collection; by selecting a plurality of frequency signals covering a wider frequency range, the resistivity and phase information of the underground medium at different frequencies are obtained, and a comprehensive description of the complex geological structure is realized.

[0084] In the embodiment, the frequency ratio between the frequencies transmitted by each channel of the multi-channel frequency division electrical method transmitter is greater than 1, so as to reduce the possibility of signal overlap and distinguish the geoelectric response at different frequencies.

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

[0086] In the embodiment, a dead time period is set between the adjacent two frequencies transmitted by each channel, the dead time period refers to the time period during which the corresponding channel does not transmit signals, and the length of the dead time period is not less than half the period of the highest frequency signal of the adjacent two frequencies, wherein the dead time periods between all adjacent two frequencies are set to the same length, such as half the period of the highest frequency among all frequency signals (or other certain fixed length), or different lengths, which are not limited.

[0087] In the embodiment, as shown in Figure 2 , the length of the dead time period between the adjacent frequencies of each channel is 0.125s.

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

[0089] The electrode device includes a four-pole device, a three-pole device, and a two-pole device, and the following describes the four-pole device, the three-pole device, and the two-pole device for step S104.

[0090] (I) Four-pole device

[0091] Specifically, in the case where the electrode device adopts a four-pole device, the current value of each frequency transmitted by each channel of the multi-channel frequency division electrical method transmitter at each pair of moving power supply points is obtained , , wherein i represents the number of a certain pair of moving power supply points, , r4 is the number of moving power supply points of the four-pole device, , and f represents the frequency of the frequency signal transmitted by the channel. The transmitted frequency value; wherein [1, p] is the total number of frequencies transmitted by each channel of the multi-channel frequency division electrical method transmitter.

[0092] As shown in Figure 2 and Figure 3 , in the case of exploration using a four-pole device and a three-channel frequency division electrical method transmitter, the current value of each frequency transmitted by each channel of the three-channel frequency division electrical method transmitter at each mobile power supply point pair A1B1, A2B2, A3B3 is obtained ; wherein, represents the number of a certain mobile power supply point, and A1B1, A2B2, A3B3 is the mobile power supply point pair A1B1, A2B2, A3B3, the frequency value transmitted by a certain mobile power supply point pair, as shown in Figure 2 0.5, 1, 2 Hz; wherein [1, p]; p is the total number of frequencies transmitted by each channel of the multi-channel frequency division electrical method transmitter, and the total number of frequencies is 3.

[0093] (II) Three-pole device

[0094] Specifically, in the case of using a three-pole device for the electrode device, the current value of each frequency transmitted by each channel of the multi-channel frequency division electrical method transmitter at each mobile power supply point and the infinite power supply point is obtained , represents the number of a certain mobile power supply point, , is the number of mobile power supply points of the three-pole device, is the frequency value transmitted by a certain mobile power supply point and the fixed infinite power supply point; wherein [1, p]; p is the total number of frequencies transmitted by each channel of the multi-channel frequency division electrical method transmitter.

[0095] As shown in Figure 2 and Figure 4 , in the case of exploration using a three-pole device and a three-channel frequency division electrical method transmitter, the current value of each frequency transmitted by each channel of the three-channel frequency division electrical method transmitter at each mobile power supply point A1~A6 and the infinite power supply point C is obtained ; wherein, represents the number of a certain mobile power supply point, and A1~A6 is the mobile power supply point; is the frequency value transmitted by a certain mobile power supply point and the fixed infinite power supply point C, as shown in Figure 2 0.5, 1, 2 Hz; wherein [1, p]; p is the total number of frequencies transmitted by each channel of the multi-channel frequency division electrical method transmitter, and the total number of frequencies is 3.

[0096] (Three) two electrode device

[0097] Specifically, in the case of using two electrode device in electrode device, the current value of each frequency sent by each channel of multi-channel frequency division electric method transmitter at each mobile power supply point and infinite power supply point is obtained , indicates the number of a certain mobile power supply point, , is the number of mobile power supply points of two electrode device, is the frequency value sent by a certain mobile power supply point and fixed infinite power supply point; wherein [1,p]; p is the total number of frequencies sent by each channel of multi-channel frequency division electric method transmitter.

[0098] As shown in Figure 2 and Figure 5 , in the case of using two electrode device and three-channel frequency division electric method transmitter for exploration, the current value of each frequency sent by each channel of three-channel frequency division electric method transmitter at each mobile power supply point A1-A6 and infinite power supply point C is obtained ; wherein, indicates the number of a certain mobile power supply point, mobile power supply point A1-A6; is the frequency value sent by a certain mobile power supply point and fixed infinite power supply point C, such as 0.5, 1, 2 Hz shown in Figure 2 ; wherein [1,p]; p is the total number of frequencies sent by each channel of multi-channel frequency division electric method transmitter. The total number of frequencies is 3.

[0099] It should be noted that when each channel of multi-channel frequency division electric method transmitter supplies power through a certain mobile power supply point, the current value of the same frequency is constant; the power supply point in conventional electric method exploration refers to the power supply point which is close to the measurement point and can produce obvious potential difference signal at the measurement point; while the infinite power supply point refers to the fixed power supply point which is far away from the measurement point and produces negligible potential difference signal at the measurement point; in this embodiment, in order to avoid confusion, the power supply point in conventional electric method exploration is named as mobile power supply point, so as to be distinguished from the infinite power supply point; the mobile power supply point and the infinite power supply point are collectively referred to as power supply point.

[0100] Step S105, obtaining the potential difference of different frequencies measured by multi-channel frequency division electric method receiver at measurement electrode pair and the phase difference of potential difference of corresponding frequency relative to the same frequency power supply current which is synchronized in time with multi-channel frequency division electric method transmitter;

[0101] In the embodiment, before using the multi-channel frequency division electro method receiver, the multi-channel frequency division electro method receiver needs to be synchronized in time with the multi-channel frequency division electro method transmitter to realize the correlation processing between the power supply current and the potential difference.

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

[0103] It should be noted that the time synchronization error of the multi-channel frequency division electro method transmitter and the multi-channel frequency division electro method receiver is not more than 100 nanoseconds.

[0104] In the multi-channel frequency division electro method, the signals sent by different channels have different frequencies, and the signal switching time interval is short (such as the dead time 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 problem; by controlling the time synchronization error within 100 nanoseconds, it is ensured that the receiver can accurately capture the start and end time of each frequency signal, avoid signal aliasing, and improve the accuracy of signal separation; for high frequency signals, such as tens of kHz or higher, the period time is very short, for example, the period of a 10 kHz signal is 100 microseconds, and the time synchronization error is less than 100 nanoseconds, which accounts for only one thousandth of the period, and almost has no impact on the collection of high frequency signals, thereby supporting wideband detection tasks.

[0105] The electrode device includes a four-pole device, a three-pole device and a two-pole device, and the steps S105 will be described below with respect to the four-pole device, the three-pole device and the two-pole device.

[0106] (I) Four-pole device

[0107] The specific requirements for the potential test in the four-pole device are as follows: in the case of using the four-pole device in the electrode device, the multi-channel frequency division electro method receiver is used to measure the potential of different frequencies on the measurement electrode M and the measurement electrode N, wherein the measurement electrode M and the measurement electrode N form a measurement electrode pair, and the measurement time on each pair of measurement electrodes is not less than the total time length of all frequencies sent by the multi-channel frequency division electro method transmitter; ​

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

[0109] In the case of exploration with a four-pole device, the implementation of step S105 is specifically: measuring the potential difference of different frequencies supplied by all measuring electrodes M and the corresponding moving power supply point on measuring electrode N when the moving power supply point in the exploration area is powered and the phase difference of the potential difference of the corresponding frequency with respect to the power supply current of the same frequency .

[0110] As shown in Figure 3 , in this embodiment, when each pair of moving power supply points in the exploration area is powered , the potential difference of different frequencies supplied by the corresponding power supply points on measuring electrode M and measuring electrode N and the phase difference of the potential difference of the corresponding frequency with respect to the power supply current of the same frequency .

[0111] (II) Three-pole device

[0112] The specific requirements for potential testing in a three-pole device are as follows: in the case of an electrode device using a three-pole device, a multi-channel frequency-division electric method receiver is used to measure the potential of different frequencies on measuring electrode M and measuring electrode N, where measuring electrode M and measuring electrode N form a pair of measuring electrodes, and the measured time on each pair of measuring electrodes is not less than the total time length of the multi-channel frequency-division electric method transmitter sending all frequencies.

[0113] In this embodiment, the total time length of each channel of the three-channel frequency-division electric method transmitter sending all frequencies is 12s, so the measured time on each pair of measuring electrodes is not less than 12s.

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

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

[0116] The start and end time of all frequencies recorded by the time-synchronized multi-channel frequency division electric method transmitter and multi-channel frequency division electric method receiver can identify which frequency from which mobile power supply point at a certain time.

[0117] (Three) diode device

[0118] The specific requirements for the test of potential in the diode device are as follows: in the case of adopting the diode device in the electrode device, the multi-channel frequency division electric method receiver is used to measure the potential of different frequencies on a certain measurement electrode M and a fixed infinite measurement electrode, wherein the measurement electrode M and the infinite measurement electrode form a measurement electrode pair, and the measurement time on each pair of measurement electrodes is not less than the total time length of all frequencies sent by the multi-channel frequency division electric method transmitter.

[0119] In the case of exploration by adopting the diode device, the implementation of step S105 is specifically: measuring the potential difference of different frequencies supplied by the corresponding power supply points on all measurement electrodes M and the fixed infinite measurement electrode when the mobile power supply point and the fixed infinite power supply point in the exploration area are powered And the phase difference of the potential difference of the corresponding frequency with respect to the power supply current of the same frequency .

[0120] As Figure 5 shown, in the present embodiment, the potential difference of different frequencies supplied by the corresponding power supply points on the measurement electrode M and the measurement electrode N when the mobile power supply point and the fixed infinite power supply C point in the exploration area are powered And the phase difference of the potential difference of the corresponding frequency with respect to the power 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 the device coefficient of coordinate conversion based on the coordinates;

[0122] In the present embodiment, in order to facilitate the calculation of subsequent device coefficients, the coordinates of all measurement electrodes and all power supply points adopt the geodetic kilometer coordinate system; the existing algorithm is used to determine the device coefficient of coordinate conversion based on the tested coordinates, such as using the device coefficient formula of the conductive method to calculate the device coefficient according to the coordinates of the power supply point and the measurement 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 four-pole device, a three-pole device and a diode device, and each electrode device corresponds to a corresponding calculation formula.

[0126] The following describes step S108 with respect to a quadrupole device, a triode device, and a diode device.

[0127] (1) Quadrupole device

[0128] In the case where the electrode device employs a quadrupole device, the apparent resistivity parameter is calculated using the formula wherein [1, p], r4 is the number of mobile power supply points of the quadrupole device; denotes the number of a certain pair of mobile power supply points; denotes the frequency value transmitted by a certain pair of mobile power supply points denotes the device coefficient converted from the coordinates of a certain pair of mobile power supply points and a certain pair of measurement electrodes M and N; denotes the potential difference measured at a certain pair of measurement electrodes M and N when the frequency value transmitted by a certain pair of mobile power supply points Bi is denotes the current value when the frequency value transmitted by a certain pair of mobile power supply points Bi is denotes the current value when the frequency value transmitted by a certain pair of mobile power supply points Bi is denotes the current value when the frequency value transmitted by a certain pair of mobile power supply points

[0129] (2) Triode device

[0130] In the case where the electrode device employs a triode device, the apparent resistivity parameter is calculated using the formula wherein [1, p], , r3 is the number of mobile power supply points of the triode device; denotes the number of a mobile power supply point; denotes the frequency value transmitted by a mobile power supply point and an infinite power supply point; denotes the device coefficient converted from the coordinates of a mobile power supply point , an infinite power supply point, and a certain pair of measurement electrodes M and N; denotes the potential difference measured at a certain pair of measurement electrodes M and N when the frequency value transmitted by a mobile power supply point and an infinite power supply point is denotes the potential difference measured at a certain pair of measurement electrodes M and N when the frequency value transmitted by a mobile power supply point and an infinite power supply point is denotes the current value when the frequency value transmitted by a mobile power supply point and an infinite power supply point is

[0131] (3) Diode device

[0132] In the case where the electrode device employs a diode device, the apparent resistivity parameter is calculated using the formula wherein the formula [1,p], the number of mobile power supply points; representing the number of mobile power supply points; mobile power supply points and the frequency value of the signal transmitted by the infinite power supply point; mobile power supply points and the device coefficient converted from the coordinates of a certain measurement electrode M; mobile power supply points and the frequency value transmitted by the infinite power supply point; mobile power supply points and the frequency value transmitted by the infinite power supply point;

[0133] In step S109, the apparent resistivity and phase difference of all frequencies of all measurement electrodes are analyzed to obtain the interpretation results.

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

[0135] The terms "comprising", "containing", or any other similar term are intended to encompass non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or inherent to such a process, method, article or device.

[0136] The above description is only the preferred embodiment of the present application and the explanation of the applied technical principles. Those skilled in the art should understand that the application scope involved in the present application is not limited to the technical solutions formed by the specific combination of the above technical features, and should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the above application concept. For example, the above features are replaced with the technical features with similar functions applied in the present application (but not limited to) to form technical solutions.

Claims

1. An exploration method based on frequency division multiplexing (FDM) of frequency signals, characterized in that, include: Based on the exploration objectives and requirements, the frequency value and number of frequencies transmitted by each channel of the multi-channel frequency division multiplexing (FDM) transmitter are determined, wherein the number of frequencies is not less than the number of channels of the multi-channel FDM transmitter, and the frequency value and number of frequencies transmitted by each channel of the multi-channel FDM transmitter are the same. Determining the number of mobile power supply points using an electrode device based on resistivity profile method; Each channel of the multi-channel frequency division transmitter is used to send a frequency-converted signal underground. Obtain the current value at each frequency of 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 difference at different frequencies and the phase difference of the corresponding frequency potential difference relative to the same frequency power supply current on the measuring electrode pair by the multi-channel frequency division current receiver that is time-synchronized with the multi-channel frequency division current transmitter. The coordinates of all measuring electrode pairs and all moving power supply points are measured, and the device coefficients for coordinate conversion are determined based on the coordinates. Formula for obtaining the apparent resistivity parameter corresponding to the electrode device; Calculate the apparent resistivity based on the aforementioned apparent resistivity parameter formula; The apparent resistivity and phase difference of all frequencies of all measuring electrodes were analyzed to obtain the interpretation results; The characteristic of the frequency-converted signal transmitted by each channel of the multi-channel frequency division multiplexing transmitter satisfies: Each channel transmits only one of the selected transmission frequencies at any given time; the frequency values ​​of the frequency-converted signals transmitted by each channel are different at the same time; the transmission time of a certain frequency in the frequency-converted signals transmitted by each channel is an integer multiple of one cycle of that frequency; the frequency-converted signals transmitted by each channel contain all frequencies of the selected frequency.

2. The method according to claim 1, characterized in that, The electrode device includes one of a quadrupole device, a triode device, and a diode device. The electrode device based on the resistivity profile method determines the number of movable power supply points, including: When a quadrupole electrode device is used, 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 transmitter. When the electrode device adopts a three-electrode device or a two-electrode 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 acquisition of the current value at each frequency transmitted by each channel of the multi-channel frequency division multiplexing transmitter at the mobile power supply point includes: When a quadrupole electrode device is used, the multi-channel frequency division multiplexing transmitter is used to obtain the signal at each pair of moving power supply points for each channel. Current value at each frequency transmitted , This indicates the number of a pair of mobile power supply points. r4 represents the number of mobile power supply points for the quadrupole device. For a pair of mobile power supply points The frequency value transmitted; where p is the total number of frequencies transmitted by each channel of the multi-channel frequency division multiplexing transmitter; When the electrode device employs a three-electrode or two-electrode configuration, the current value at each frequency transmitted by each channel of the multi-channel frequency division current transmitter at each moving power supply point and infinity power supply point is obtained. , This indicates the number of a mobile power supply point. , The number of mobile power supply points for the triode device. The number of mobile power supply points for the diode device. For a mobile power supply point The frequency value transmitted from a fixed power supply point at infinity; where p represents the total number of frequencies transmitted by each channel of the multi-channel frequency division multiplexing transmitter.

4. The method according to claim 1, characterized in that, Before acquiring the potential difference at different frequencies measured on the measuring electrode pair by the multi-channel frequency division multiplexing receiver synchronized with the multi-channel frequency division multiplexing transmitter in time, the method further includes: When the electrode device adopts a quadrupole or tripole device, a multi-channel frequency division method receiver is used to measure the potential at different frequencies on the measuring electrode M and the measuring electrode N. The measuring electrode M and the measuring electrode N form a measuring electrode pair. The measurement time on each measuring electrode pair is not less than the total time length of all frequencies transmitted by the multi-channel frequency division method transmitter. When the electrode device adopts a two-electrode device, a multi-channel frequency division method receiver is used to measure the potential of different frequencies on a certain measuring electrode M and a fixed infinity measuring electrode. The measuring electrode M and the infinity 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 transmitted by the multi-channel frequency division method transmitter.

5. The method according to claim 1, characterized in that, The acquisition of the potential difference at different frequencies measured on the measuring electrode pair by the multi-channel frequency division multiplexing (FDM) receiver, which is time-synchronized with the multi-channel FDM transmitter, and the phase difference of the corresponding frequency potential difference relative to the supply current of the same frequency, includes: When a quadrupole electrode setup is used, the potential difference of different frequencies supplied by the corresponding mobile power supply points on all measuring electrodes M and N is measured when the mobile power supply points within the exploration area are powered. and the phase difference of the potential difference at the corresponding frequency relative to the supply current at the same frequency. ; When a three-electrode setup is used, and the moving power supply point and the fixed infinity power supply point are both located within the exploration area, the potential differences of different frequencies supplied by the corresponding power supply points on all measuring electrodes M and N are measured. and the phase difference of the potential difference at the corresponding frequency relative to the supply current at the same frequency. ; When a diode electrode setup is used, the potential difference of different frequencies supplied by the corresponding power supply points on all measuring electrodes M and the fixed infinity measuring electrode is measured when the moving power supply point and the fixed infinity power supply point are both located within the exploration area. and the phase difference of the potential difference at the corresponding frequency relative to the supply current at the same frequency. .

6. The method according to claim 1, characterized in that, The calculation of apparent resistivity based on the apparent resistivity parameter formula includes: When a four-electrode electrode system is used, the formula is applied. Calculate the apparent resistivity parameter; in, , r4 represents the number of mobile power supply points for the quadrupole device; Indicates the number of a pair of mobile power supply points; For a pair of mobile power supply points The frequency value transmitted; To determine the location of a certain pair of mobile power supply points The device coefficients for coordinate conversion between a pair of measuring electrodes M and N; For a pair of mobile power supply points Bi sent The frequency value is the potential difference measured on a pair of measuring electrodes M and N; For a pair of mobile power supply points The sent Current value at the specified frequency; When a three-electrode electrode device is used, the formula is adopted. Calculate the apparent resistivity parameter; in, , , The number of mobile power supply points for the triode device; Indicates the number of the mobile power supply point; Mobile power supply point The frequency value of the signal transmitted by the power supply point at infinity; To provide power to mobile power supply points The device coefficients for coordinate conversion between the power supply point at infinity and a pair of measuring electrodes M and N; Mobile power supply point And the signal sent from the infinity power supply point The frequency value is the potential difference measured on a pair of measuring electrodes M and N; Mobile power supply point And the signal sent from the infinity power supply point Current value at the specified frequency; When a diode electrode device is used, the formula is applied. Calculate the apparent resistivity parameter; In the formula , The number of mobile power supply points for the diode device; Indicates the number of the mobile power supply point; Mobile power supply point The frequency value of the signal transmitted by the power supply point at infinity; To provide power to mobile power supply points The device coefficient for coordinate conversion with a certain measuring electrode M; Mobile power supply point And the signal sent from the infinity power supply point The frequency value is the potential difference measured between a certain measuring electrode M and the measuring electrode D at infinity; Mobile power supply point And the signal sent from the infinity power supply point Current value at a given frequency.

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 time period is set between two adjacent frequencies transmitted by each channel. The dead time period refers to the period during which the corresponding channel does not transmit a signal. The length of the dead time period is not less than half the duration of the highest frequency signal among the two adjacent frequencies.

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

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

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