A three-dimensional direct current method data acquisition system and method

Abstract

The application discloses a three-dimensional direct current method data acquisition system and method, and the three-dimensional direct current method data acquisition method utilizes conventional high-density electrical method equipment to realize three-dimensional direct current method exploration through external connection of a large electrode distance cable, definition of a composite device and multi-line data rolling acquisition, can effectively increase the penetration of conductive strata, and can increase the exploration depth by 2 to 4 times compared with a traditional method, can effectively increase the lateral resolution in the vertical line direction while maintaining the near-surface resolution, and can realize rapid data analysis by using multi-pole distance intermediate gradient sounding data.

Description

Technical Field

[0001] This invention relates to the field of geophysical exploration technology, specifically to a three-dimensional direct current resistivity data acquisition system and method. Background Technology

[0002] Electrical resistivity tomography (ERT) is one of the most widely used geophysical exploration methods in geological exploration. Its principle is based on the electrical differences of underground rocks (minerals). A stable DC electric field is artificially established underground, and the electrical parameters of the underground medium are measured by two or more sets of electrodes. The variation law is analyzed, thereby inferring the underground geological structure, stratigraphic properties and hydrogeological conditions.

[0003] High-density electrical resistivity tomography (EPT) is one of the commonly used techniques in electrical exploration. It involves deploying multiple sets of electrodes simultaneously, with automatic electrode movement controlled by a controller, to simultaneously achieve resistivity depth measurement and profile measurement, offering high measurement efficiency and data density. However, conventional high-density EPT is limited by the array length, device type, and operating methods, resulting in limitations in exploration depth and spatial resolution. This makes it difficult to achieve high-resolution imaging of deep targets, especially in complex geological environments where exploration faces numerous challenges.

[0004] Furthermore, current DC electrical resistivity tomography (EDT) is primarily two-dimensional. In practical engineering, geological structures and target bodies typically exhibit complex three-dimensional spatial distributions. Two-dimensional EDT struggles to accurately reflect the spatial location and morphology of anomalies, making geological interpretation of these anomalies challenging. Three-dimensional EDT, however, can effectively address these issues. When using high-density EDT equipment for three-dimensional EDT, parallel or mesh-like survey lines are typically used. These lines collect data independently and without correlation, resulting in a lack of spatial correlation and effectively creating "pseudo-three-dimensional" exploration that fails to accurately reflect the spatial location and morphology of anomalies. Summary of the Invention

[0005] The purpose of this invention is to overcome at least one defect in the prior art and to provide a three-dimensional DC electrical resistivity data acquisition system and method. This invention achieves true three-dimensional data acquisition through multi-line rolling acquisition.

[0006] The technical solution of this invention is implemented as follows: This invention discloses a three-dimensional DC electrical resistivity data acquisition system, including a power supply, a measurement host, an electrode converter, and a first measuring cable and a second measuring cable. The power supply is used to provide power to the entire system. The electrode converter is connected to the measurement host. The first measuring cable and the second measuring cable are connected to the electrode converter. The first measuring cable and the second measuring cable are formed by connecting at least one second cable in series. The two ends of the first measuring cable or the second measuring cable are respectively connected to a first cable. A plurality of first electrodes are connected to the first cable, and a plurality of second electrodes are connected to the second cable. The interval between two adjacent first electrodes connected to the first cable is greater than the interval between two adjacent second electrodes connected to the second cable.

[0007] In some embodiments, the measurement host is a high-density electrical resistivity meter;

[0008] or / and,

[0009] The first cable is a large-pitch cable;

[0010] or / and,

[0011] The second cable is a centralized cable.

[0012] In some embodiments, the two ends of the first test cable or the second test cable are respectively connected to the first cable through a cable connector. When the first test cable and the second test cable are composed of multiple second cables connected in series, two adjacent second cables are connected in series through a cable connector. The electrode converter is connected to the cable connector.

[0013] The first electrodes connected by the two first cables are arranged symmetrically.

[0014] In some embodiments, the spacing between two adjacent first electrodes is n times the spacing between two adjacent second electrodes.

[0015] This invention discloses a three-dimensional direct current resistivity data acquisition method, comprising the following steps:

[0016] Step 1: Design several survey lines in parallel across the survey area according to the task requirements;

[0017] Step 2: Lay out the first measuring line cable and the second measuring line cable respectively. The first measuring line cable and the second measuring line cable are connected to the electrode converter, and the electrode converter is connected to the measuring host.

[0018] Step 3: Connect the first cable to both ends of the first measuring line cable and collect the middle gradient depth measurement data to obtain the middle gradient depth measurement data;

[0019] The first measuring line is used as the power supply measuring line, and the second measuring line is used as the measurement measuring line. A series of measurement pole spacings and corresponding interval coefficient sequences are defined for data acquisition.

[0020] Step 4: When there are more than 2 survey lines, move the first survey line cable from the first survey line to the third survey line, disconnect the first cable at both ends of the first survey line cable, connect the first cable to both ends of the second survey line cable, and collect the middle gradient depth data to obtain the middle gradient depth data.

[0021] The second measuring line is used as the power supply measuring line, and the third measuring line is used as the measurement measuring line. A series of measurement pole spacings and corresponding interval coefficient sequences are defined for data acquisition.

[0022] This process continues until data collection for all survey lines is completed.

[0023] In some embodiments, the mid-step depth sounding data acquisition specifically includes:

[0024] S1: The first measuring cable and the second measuring cable are formed by connecting at least one second cable in series. Several first electrodes are connected to the first cable, and several second electrodes are connected to the second cable. Two first electrodes are used as power supply electrodes AB, and two second electrodes are used as measuring electrodes MN. The measuring electrodes MN are located between the power supply electrodes AB. The initial power supply electrode spacing and the measuring electrode spacing are determined.

[0025] S2: Keeping the power supply electrode spacing and the measuring electrode spacing constant, measure point by point along the measuring line to complete one middle step sweep measurement;

[0026] S3: Change the electrode spacing of the power supply electrodes AB, repeat step S2 to perform mid-gradient surface scanning measurement, and obtain multi-electrode mid-gradient depth measurement data.

[0027] In some embodiments, after step S3 is completed, the distance of the measuring electrode MN is changed, and steps S2 to S3 are repeated to obtain more measurement data.

[0028] In some embodiments, when performing mid-gradient depth sounding, the distance between the measuring electrode MN is selected as 1 to 2 electrode distances, and the distance between the power supply electrode AB is selected as 3 to 5 times the exploration depth.

[0029] In some embodiments, after collecting depth sounding data along the gradient in each survey line, the following steps are further included: disconnecting the first cable, customizing the measurement pole spacing series and the corresponding interval coefficient sequence, and collecting data from the mixing device along each survey line.

[0030] In some embodiments, data acquisition of the line mixing device includes: disconnecting the first cable, using the Nth test line as the power supply test line, using the N+1th test line as the measurement test line, customizing the measurement pole spacing series and the corresponding interval coefficient sequence, and acquiring data of the line mixing device between the Nth test line and the N+1th test line.

[0031] In some embodiments, the three-dimensional DC electrical resistivity data acquisition method of the present invention further includes step 5: after completing the data acquisition of all survey lines, according to the abnormal data distribution characteristics, horizontally arrange connecting survey lines and supplement the data acquisition of mixed devices within or between lines.

[0032] The present invention has at least the following beneficial effects: The three-dimensional DC electrical resistivity tomography data acquisition device and method proposed in this invention utilize conventional high-density electrical resistivity equipment to achieve three-dimensional DC electrical resistivity tomography exploration through external large-pole-gap cables, defined composite devices, and rolling acquisition of multi-line data. This can effectively increase the penetration of conductive strata, while increasing the exploration depth by 2 to 4 times compared with traditional methods. While maintaining near-surface resolution, it effectively increases the lateral resolution in the direction perpendicular to the survey line, and can achieve rapid data analysis by utilizing multi-pole-gap gradient sounding data. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 A schematic diagram of a three-dimensional DC electrical resistivity data acquisition system provided in one embodiment of the present invention (showing only one measuring cable);

[0035] Figure 2 A flowchart illustrating the workflow of a three-dimensional direct current resistivity data acquisition method according to an embodiment of the present invention;

[0036] Figure 3 The data spatial distribution diagrams of the hybrid device provided in the embodiments of the present invention are as follows: (a) is a data spatial distribution diagram of dipole-dipole and intermediate ladder hybrid device; (b) is a data spatial distribution diagram of positive and negative tripolar, intermediate ladder, and intermediate ladder depth sounding hybrid device; and (c) is a data spatial distribution diagram of intermediate ladder and intermediate ladder depth sounding hybrid device.

[0037] Figure 4 This is a schematic diagram for measuring a polar distance of a and an interval coefficient of n;

[0038] Figure 5 This is a schematic diagram of a series of polar distance measurements and the corresponding interval coefficient sequence. Detailed Implementation

[0039] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] In the description of this invention, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0041] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature; in the description of this invention, unless otherwise stated, "a plurality of" or "several" means two or more.

[0042] Electrical resistivity tomography (ERT) is one of the most widely used geophysical exploration methods in geological exploration. It is a type of direct current electric method (DCE). Based on the differences in the electrical properties of underground rocks (ores), a stable DC electric field is artificially established underground. Two or more sets of electrodes are used to measure the electrical parameters of the underground medium, analyze their variation patterns, and thus solve related geological problems.

[0043] Currently, DC electrical resistivity exploration typically employs high-density electrical resistivity equipment, which deploys multiple sets of electrodes at once and automatically moves the electrodes via a controller, simultaneously achieving resistivity depth measurement and profile measurement. It features high measurement efficiency and high data density.

[0044] Direct current methods include resistivity profiling, resistivity depth measurement, charging method, and excited polarization method.

[0045] The resistivity sounding method is based on the electrical differences of underground rocks (minerals). It artificially establishes a stable DC electric field underground and observes and analyzes the resistivity variation of rock (mineral) layers at different depths in the vertical direction at the same measuring point by gradually increasing the power supply and the electrode spacing.

[0046] The resistivity profiling method is based on the electrical differences of underground rocks (minerals). It involves artificially establishing a stable DC electric field underground, keeping the electrode spacing constant, and observing point by point along the survey line to analyze the variation law of the resistivity of the rock (mineral) layer in the horizontal direction within a certain depth range.

[0047] The high-density electrical resistivity method (HID method) is based on the electrical differences of underground rocks (minerals). It artificially establishes a stable DC electric field underground and uses electrode array technology to simultaneously measure resistivity depth and resistivity profile, thereby obtaining the resistivity distribution law of underground rock (mineral) layers in two or three dimensions.

[0048] In addition, the intermediate gradient method is a commonly used and important method in DC resistivity tomography. This method keeps the power supply electrode stationary at the distance from AB and the distance between the measuring electrodes MN constant. The electrode moves point by point along the survey line within the middle 1 / 2 to 1 / 3 of AB, observing the potential difference between MN and calculating the apparent resistivity value at each measuring point (midpoint of MN). Its exploration depth is approximately 1 / 6 of the length of AB. When using high-density resistivity tomography equipment, the exploration depth is limited by the working array length. To address this problem, this invention increases the array length by using an external large-pole cable, while avoiding the addition of ineffective electrodes, to achieve multi-pole intermediate gradient depth sounding, thereby enabling rapid data acquisition and analysis.

[0049] like Figure 4 The measured polar distance is 'a', and the interval coefficient is 'n'. Customizing the measured polar distance series and corresponding interval coefficient sequences refers to selecting different values ​​of 'a' and 'n' for data acquisition as needed. For example, 'a' and 'na' can be multiples of the basic track spacing in an arithmetic sequence, such as... Figure 5 As shown, one example is that the distance between the measuring electrodes P1 and P2 is set sequentially in multiples of the channel pitch [1 to 5]. Corresponding to each measurement sequence, the distance between the power supply electrodes C1 and C2 is set in multiples of the channel pitch as {1 to 6}, {6 to 11}, {11 to 16}, {16 to 21}, and {21}. The values ​​of a and n in this invention are selected as needed and are not limited to the above example.

[0050] This invention provides a novel three-dimensional DC electrical resistivity tomography (DCIP) data acquisition device and method. Based on existing high-density DCIP equipment, it uses an external large-pitch cable to simultaneously perform intermediate gradient profile measurements and electrical sounding measurements. Compared with conventional acquisition devices and methods, it reduces the boundary blind zone and increases the exploration depth while ensuring data density.

[0051] Example 1

[0052] See Figure 1This invention provides a three-dimensional DC electrical resistivity data acquisition system, including a power supply, a measurement host, an electrode converter, and a first and second measuring cable. The power supply provides power to the entire system. The electrode converter is connected to the measurement host. The first and second measuring cables are connected to the electrode converter. The first and second measuring cables are formed by connecting at least one second cable in series. Each end of the first or second measuring cable is externally connected to a first cable. A plurality of first electrodes are connected to the first cable, and a plurality of second electrodes are connected to the second cable. The interval between two adjacent first electrodes connected to the first cable is greater than the interval between two adjacent second electrodes connected to the second cable.

[0053] In some embodiments, the measuring host is a high-density electrical resistivity meter; the first cable is a large-pitch cable; and the second cable is a conventional cable, such as a centralized cable.

[0054] In some embodiments, the two ends of the first test cable or the second test cable are respectively connected to the first cable through a cable connector. When the first test cable and the second test cable are composed of multiple second cables connected in series, two adjacent second cables are connected in series through a cable connector. The electrode converter is connected to the cable connector.

[0055] The first electrodes connected by the two first cables are arranged symmetrically.

[0056] In some embodiments, the spacing between two adjacent first electrodes is n times the spacing between two adjacent second electrodes, that is, the electrode spacing of a large-pitch cable is n times the electrode spacing of a conventional cable (n>1). n is generally taken as an integer.

[0057] The power supply for this invention can be a battery box. The high-density electrical resistivity meter main unit can utilize existing commercially available high-density electrical resistivity instruments. The electrode converter is connected to the high-density electrical resistivity meter main unit and is controlled by it for measurement. The battery box is connected to the electrode converter to provide a stable current to the measurement system. Conventional cables are directly connected to the high-density electrical resistivity meter main unit or other conventional cables. Large-pitch cables are connected to conventional cables at the end of the array. Cable connectors are used to connect conventional cables in series, as well as conventional cables and large-pitch cables. Electrodes are used to measure underground potential and current.

[0058] In some embodiments, the high-density electrical resistivity meter host supports a series centralized cable connection, which can connect no less than 4 cables and supports custom acquisition parameters.

[0059] In some embodiments, the electrode converter is controlled by the high-density electrical resistivity instrument host, thereby controlling the electrodes for power supply and measurement.

[0060] In some embodiments, the conventional cable is a centralized cable, and several electrodes can be connected to the cable. Multiple conventional cables can be connected together through the cable connector to form a test line cable.

[0061] In some embodiments, multiple conventional cables connected in series are connected to an electrode converter to form a conventional measurement arrangement.

[0062] In some embodiments, the large-pitch cable is a centralized cable, on which several electrodes can be connected. The large-pitch cable is connected to the two conventional cables at the end of the conventional measurement arrangement described above via a cable connector.

[0063] In some embodiments, the electrodes connected to the conventional cable and the large-pitch cable are evenly spaced, except that the spacing between the electrodes connected to the large-pitch cable is n times that of the electrodes connected to the conventional cable.

[0064] Example 2

[0065] See Figure 2 This invention discloses a three-dimensional direct current resistivity data acquisition method, comprising the following steps:

[0066] Step 1: Design several parallel survey lines in the survey area according to the task requirements, namely the first survey line, the second survey line, the third survey line, etc.

[0067] Step 2: Lay out the first measuring line cable and the second measuring line cable respectively, and connect the first cable to both ends of the first measuring line cable located on the first measuring line. Connect the electrode converter to the measuring host. Connect the first measuring line cable and the second measuring line cable to the electrode converter. The first measuring line cable and the second measuring line cable are formed by connecting at least one second cable in series. A plurality of first electrodes are connected on the first cable and a plurality of second electrodes are connected on the second cable. The interval between two adjacent first electrodes connected on the first cable is greater than the interval between two adjacent second electrodes connected on the second cable.

[0068] Step 3: Collect multi-pole mid-gradient depth sounding data on the first survey line to obtain multi-pole mid-gradient depth sounding data;

[0069] Disconnect the first cable, customize the measurement pole spacing series and the corresponding interval coefficient sequence, and perform data acquisition of the mixing device on the first measurement line;

[0070] The first measuring line is used as the power supply measuring line, and the second measuring line is used as the measurement measuring line. A series of measurement pole spacings and corresponding interval coefficient sequences are defined, and data is collected from the first and second measuring lines by the line mixing device.

[0071] Step 4: When there are more than 2 survey lines, move the first survey line cable from the first survey line to the third survey line, disconnect the first cable at both ends of the first survey line cable, and connect the first cable to both ends of the second survey line cable located at the second survey line at this time. Perform multi-pole mid-step depth sounding data acquisition on the second survey line to obtain multi-pole mid-step depth sounding data.

[0072] Disconnect the first cable, customize the measurement pole spacing series and the corresponding interval coefficient sequence, and perform data acquisition of the mixing device on the second measurement line;

[0073] The second measuring line is used as the power supply measuring line, and the third measuring line is used as the measurement measuring line. A series of measurement pole spacings and corresponding interval coefficient sequences are customized, and data acquisition of the inter-line mixing device is performed on the second and third measuring lines.

[0074] When there are more than 3 survey lines, the second survey line cable is moved from the second survey line to the fourth survey line, and the first cable at both ends of the second survey line cable is disconnected. At this time, the first cable is connected to both ends of the first survey line cable located on the third survey line. Multi-pole mid-step depth sounding data is collected on the third survey line to obtain multi-pole mid-step depth sounding data.

[0075] Disconnect the first cable, customize the measurement pole spacing series and the corresponding interval coefficient sequence, and perform data acquisition of the mixing device on the third measurement line;

[0076] The third measuring line is used as the power supply measuring line, and the fourth measuring line is used as the measurement measuring line. A series of measurement pole spacings and corresponding interval coefficient sequences are defined, and data acquisition of the inter-line mixing device is carried out on the third and fourth measuring lines.

[0077] This process is repeated (i.e., rolling survey line measurement) until data collection for all survey lines is completed.

[0078] In some embodiments, the three-dimensional DC electrical resistivity data acquisition method of the present invention further includes step 5: after completing the data acquisition of all survey lines, according to the abnormal data distribution characteristics, horizontally arrange connecting survey lines and supplement the data acquisition of mixed devices within or between lines.

[0079] Based on the characteristics of abnormal data distribution, horizontal connecting survey lines are arranged to supplement the data collection of mixed devices within or between lines. Specifically, based on the profile of the measurement data, the location of suspected anomalies is identified, and multiple horizontal connecting survey lines (perpendicular or oblique to the parallel survey lines) are arranged at the location to conduct densified measurements. The horizontal connecting survey lines can also be used to conduct mixed device measurements within or between lines according to the longitudinal survey lines.

[0080] In some embodiments, multi-pole gradient sounding data acquisition is performed on the i-th survey line, specifically including:

[0081] S1: Use the two first electrodes as power supply electrodes AB and the two second electrodes as measuring electrodes MN. The measuring electrodes MN are located between the power supply electrodes AB. Determine the initial power supply electrode spacing and the measuring electrode spacing.

[0082] S2: Keeping the power supply electrode spacing and the measuring electrode spacing constant, measure point by point along the i-th measuring line to complete one middle ladder sweep measurement;

[0083] S3: Change the electrode spacing of the power supply electrodes AB, repeat step S2 to perform mid-gradient surface scanning measurement, and obtain multi-electrode spacing mid-gradient depth measurement data, i.e., multiple sets of mid-gradient surface scanning data at different depths.

[0084] In some embodiments, after step S3 is completed, the distance of the measuring electrode MN can be changed, and steps S2 to S3 can be repeated to obtain more measurement data.

[0085] In some embodiments, the multi-pole gradient depth acquisition on the i-th survey line further includes: processing and inverting multiple sets of gradient scanning data at different depths to finally obtain a DC electrical resistivity tomography profile at a greater depth.

[0086] The data processing in this invention generally includes: removing "flying points" and terrain correction. Inversion refers to calculating the subsurface true resistivity profile from the measured apparent resistivity profile, which is the final result.

[0087] In some embodiments, in step S2, the measurement point location corresponding to the measurement data is the midpoint of the measurement electrode MN, and the specific formula for calculating the depth Z of the measurement point is:

[0088] n≤3, Z=0.18AB;

[0089] 3 <n≤10,Z=0.19AB;

[0090] When n>10, Z=0.25;

[0091] Where n is the isolation coefficient (i.e., the interval coefficient), and AB is the electrode spacing of the power supply electrodes.

[0092] In other embodiments, in step S2, the measurement point corresponding to the measurement data is the midpoint of the measurement electrode MN, and the specific formula for calculating the depth of the measurement point is:

[0093]

[0094] Where α is the proportionality coefficient. The proportionality coefficient α is determined empirically, based on the distance between the measuring electrodes and the distance between the power supply electrodes.

[0095] Taking the multi-pole gradient depth sounding data acquisition on the first survey line as an example, it specifically includes:

[0096] S1: Use the two first electrodes as power supply electrodes AB and the two second electrodes as measuring electrodes MN. The measuring electrodes MN are located between the power supply electrodes AB. Determine the initial power supply electrode spacing and the measuring electrode spacing.

[0097] S2: Keeping the power supply electrode spacing and the measuring electrode spacing constant, measure point by point along the first measuring line to complete one middle ladder sweep measurement;

[0098] S3: Change the electrode spacing of the power supply electrodes AB, repeat step S2 to perform mid-gradient surface scanning measurement, and obtain multi-electrode mid-gradient depth measurement data.

[0099] In some embodiments, data acquisition of the mixing device is performed on the i-th measurement line, specifically including: customizing the measurement pole spacing series and the corresponding interval coefficient sequence, and performing data acquisition of the mixing device within the i-th measurement line.

[0100] In some embodiments, data acquisition of the inter-line mixing device is performed on the Nth and N+1th measurement lines, where N is a positive integer. Specifically, this includes: using the Nth measurement line as the power supply measurement line and the N+1th measurement line as the measurement measurement line, defining a series of measurement pole distances and corresponding interval coefficient sequences, and performing data acquisition of the inter-line mixing device on the Nth and N+1th measurement lines.

[0101] When collecting data from the inter-line mixing device on the Nth and N+1th measurement lines, the first cable can be disconnected and the second electrode of the Nth measurement line can be used as the power supply electrode. Alternatively, when collecting data from the inter-line mixing device on the Nth and N+1th measurement lines, the first cable can be kept connected and the first electrode or / and the second electrode of the Nth measurement line can be used as the power supply electrode.

[0102] Taking the data acquisition of the inter-line mixing device on the first and second measuring lines as an example, the specific steps include: using the first measuring line as the power supply measuring line and the second measuring line as the measurement measuring line, defining a series of measurement pole distances and corresponding interval coefficient sequences, and then acquiring data of the inter-line mixing device on the first and second measuring lines.

[0103] In some embodiments, the setup of the power supply and measurement electrodes can be automatically completed by the high-density electrical resistivity meter host, and the electrode switching in subsequent steps can also be automatically completed by the high-density electrical resistivity meter host. Customizing the measurement electrode spacing series and the corresponding interval coefficient sequence can be automatically completed by the high-density electrical resistivity meter host.

[0104] In some embodiments, when performing mid-gradient surface scanning measurements, the distance between the measuring electrode MN is generally selected as 1 to 2 electrode distances, and the distance between the power supply electrode AB is generally selected as 3 to 5 times the exploration depth.

[0105] In some embodiments, the hybrid device is a combination of at least two devices, including but not limited to: Wenner Alpha (WN_α), Wenner Beta (WN_β), Wenner Gamma (WN_γ), Wenner-Schlumberger (WS), pole-pole (PP), gradient (GD), dipole-dipole (DPDP), pole-dipole (PDP), and positive and negative tripolar devices. The hybrid device is determined according to the task requirements and implementation effect.

[0106] The process described above will be explained in detail below with specific examples.

[0107] See Figure 2 A three-dimensional direct current resistivity data acquisition method includes the following steps:

[0108] Step 1: Design several survey lines in parallel in the survey area according to the task requirements, including survey lines I, II, and III.

[0109] Step 2: Lay out two high-density measurement line cables, I and II, and connect large-pitch cables to both ends of the I measurement line cable. Then connect the high-density electrical resistivity meter main unit, electrode converter, battery box, electrodes, etc. in sequence.

[0110] Step 3: Set the electrode in the large-pitch cable of measurement line I as the power supply electrode AB, and set the electrode in the conventional cable of measurement line I as the measuring electrode MN. Keep the position of the power supply electrode AB unchanged and the distance of the measuring electrode MN unchanged. Move the measuring electrode MN synchronously from one end of the arrangement to the other end, measure point by point, and complete one mid-step sweep measurement.

[0111] Step 4: Change the distance between the power supply electrodes AB and repeat step 3 to perform mid-gradient surface scanning measurement to obtain multi-pole mid-gradient depth measurement data for rapid data analysis.

[0112] Step 5: Disconnect the large-pole-gap cable, customize the measurement pole-gap series and the corresponding interval coefficient sequence, and collect data from the mixing device within measurement line I;

[0113] Step 6: Use measurement line I as the power supply measurement line and measurement line II as the measurement measurement line. Define the measurement pole spacing series and the corresponding interval coefficient sequence, and collect data from the mixed device between measurement lines I and II.

[0114] Step 7: Move the high-density cable of measuring line I to measuring line III (e.g., move the cable of measuring line I parallel to the cable of measuring line III), and connect large-pitch cables to both ends of the cable of measuring line II respectively;

[0115] Step 8: Repeat steps 3 to 7 to complete the data acquisition of multi-pole depth sounding within the line, data acquisition of the mixing device within the line, and data acquisition of the mixing device between lines;

[0116] Step 9: Based on the abnormal distribution characteristics of the data, arrange the connecting survey lines horizontally and supplement the data collection of mixed devices within or between the lines;

[0117] Step 10: Complete the acquisition of three-dimensional high-density electrical resistivity tomography (EDT) data. Figure 3 The following are spatial distribution diagrams of the data of the hybrid device provided in the embodiments of the present invention: (a) is a spatial distribution diagram of the data of the dipole-dipole and intermediate ladder hybrid device; (b) is a spatial distribution diagram of the data of the positive and negative tripolar, intermediate ladder and intermediate ladder sounding hybrid device; and (c) is a spatial distribution diagram of the data of the intermediate ladder and intermediate ladder sounding hybrid device.

[0118] The main measuring instrument is a high-density electrical resistivity meter; the first cable is a large-pole cable; and the second cable is a centralized cable.

[0119] In step 3, the setting of the power supply electrode and the measuring electrode can be completed automatically by the main unit of the high-density electrical resistivity instrument. The electrode switching work in subsequent steps can also be completed automatically by the main unit of the high-density electrical resistivity instrument.

[0120] In step 3, the electrodes in the large-pitch cable are always used as power supply electrodes, and the electrodes in the conventional cable are always used as measurement electrodes.

[0121] In step 3, the distance between the measuring electrode MN is generally selected as 1 to 2 electrode distances, and the distance between the power supply electrode AB is generally selected as 3 to 5 times the exploration depth.

[0122] After step 4 is completed, the distance of the measuring electrode MN can be changed, and steps 3 to 4 can be repeated to obtain more measurement data.

[0123] In steps 5 and 6, the custom measurement pole spacing series and the corresponding interval coefficient sequence can be automatically completed using the high-density electrical resistivity meter host.

[0124] Furthermore, in steps 5 and 6, the hybrid device is a combination of at least two devices, including but not limited to: Wenner Alpha (WN_α), Wenner Beta (WN_β), Wenner Gamma (WN_γ), Wenner-Schlumberger (WS), pole-pole (PP), gradient (GD), dipole-dipole (DPDP), pole-dipole (PDP), and positive and negative tripolar devices. The hybrid device is determined according to the task requirements and implementation effect.

[0125] When using high-density electrical resistivity tomography (EPT) equipment for exploration, observations are typically conducted using a limited number of given device types. The measurement electrode spacing and interval sizes are relatively fixed, resulting in limited data acquisition, limited exploration depth, and the existence of blind zones. To address this issue, a custom series of measurement electrode spacings and corresponding interval coefficient sequences are used for multi-device combined observations. Compared to conventional devices, this approach enriches the data volume, effectively improves spatial resolution and exploration depth, and reduces blind zones.

[0126] The present invention proposes a three-dimensional DC electrical resistivity tomography (DCEP) data acquisition device and method. By using conventional high-density DCEP equipment, external large-pole-gap cables, a defined composite device, and rolling acquisition of multi-line data, three-dimensional DCEP exploration can be achieved. This can effectively increase the penetration of conductive strata, and the exploration depth is increased by 2 to 4 times compared with traditional methods. While maintaining near-surface resolution, it can effectively increase the lateral resolution in the direction perpendicular to the survey line. Furthermore, rapid data analysis can be achieved by using multi-pole-gap gradient sounding data.

[0127] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A three-dimensional direct current resistivity data acquisition method, characterized in that, Includes the following steps: Step 1: Design several survey lines in parallel across the survey area according to the task requirements; Step 2: Lay out the first measuring line cable and the second measuring line cable respectively. The first measuring line cable and the second measuring line cable are connected to the electrode converter, and the electrode converter is connected to the measuring host. Step 3: Connect the first cable to both ends of the first measuring line cable and collect the middle gradient depth measurement data to obtain the middle gradient depth measurement data; The first measuring line is used as the power supply measuring line, and the second measuring line is used as the measurement measuring line. A series of measurement pole spacings and corresponding interval coefficient sequences are defined for data acquisition. Step 4: When there are more than 2 survey lines, move the first survey line cable from the first survey line to the third survey line, disconnect the first cable at both ends of the first survey line cable, connect the first cable to both ends of the second survey line cable, and collect the middle gradient depth data to obtain the middle gradient depth data. The second measuring line is used as the power supply measuring line, and the third measuring line is used as the measurement measuring line. A series of measurement pole spacings and corresponding interval coefficient sequences are defined for data acquisition. This process continues until data collection for all survey lines is completed. The measurement point corresponding to the measurement data is the midpoint of the measurement electrode MN. The specific formula for calculating the depth Z of the measurement point is: For n ≤ 3, Z = 0.18AB; 3 < n ≤ 10, Z = 0.19AB; When n > 10, Z = 0.25; Where n is the interval coefficient and AB is the electrode spacing of the power supply electrodes; or, The measurement point corresponding to the measurement data is the midpoint of the measuring electrode MN. The specific formula for calculating the depth of the measurement point is as follows: ； Where α is the proportionality coefficient, which is determined by the distance between the measuring electrodes and the distance between the power supply electrodes.

2. The three-dimensional DC resistivity data acquisition method as described in claim 1, characterized in that: The mid-gradient depth sounding data collection includes: S1: The first measuring cable and the second measuring cable are formed by connecting at least one second cable in series. Several first electrodes are connected to the first cable, and several second electrodes are connected to the second cable. Two first electrodes are used as power supply electrodes AB, and two second electrodes are used as measuring electrodes MN. The measuring electrodes MN are located between the power supply electrodes AB. The initial power supply electrode spacing and the measuring electrode spacing are determined. S2: Keeping the power supply electrode spacing and the measuring electrode spacing constant, measure point by point along the measuring line to complete one middle step sweep measurement; S3: Change the electrode spacing of the power supply electrodes AB, repeat step S2 to perform mid-gradient surface scanning measurement, and obtain multi-electrode mid-gradient depth measurement data.

3. The three-dimensional DC resistivity data acquisition method as described in claim 2, characterized in that: After step S3 is completed, change the distance of the measuring electrode MN and repeat steps S2 to S3 to obtain more measurement data.

4. The three-dimensional DC resistivity data acquisition method as described in claim 1, characterized in that: After collecting depth sounding data along each survey line, the following steps are also included: disconnecting the first cable, customizing the measurement pole spacing series and the corresponding interval coefficient sequence, and collecting data from the mixing device along each survey line.

5. The three-dimensional DC electrical resistivity data acquisition method as described in claim 1, characterized in that: Data acquisition for the line-to-line mixing device includes: disconnecting the first cable, using the Nth measuring line as the power supply measuring line, using the N+1th measuring line as the measurement measuring line, defining a series of measurement pole distances and corresponding interval coefficient sequences, and acquiring data for the line-to-line mixing device of the Nth and N+1th measuring lines.

6. The three-dimensional DC resistivity data acquisition method as described in claim 1, characterized in that: It also includes step 5: After completing the data collection of all survey lines, based on the abnormal distribution characteristics of the data, horizontally arrange connecting survey lines and supplement the data collection of mixed devices within or between lines.

7. A three-dimensional DC resistivity data acquisition system, characterized in that: The system includes a power supply, a measurement host, an electrode converter, and a first and a second measuring cable. The power supply provides power to the entire system. The electrode converter is connected to the measurement host. The first and second measuring cables are connected to the electrode converter. The first and second measuring cables are formed by connecting at least one second cable in series. The two ends of the first and second measuring cables are respectively connected to a first cable. A plurality of first electrodes are connected to the first cable, and a plurality of second electrodes are connected to the second cable. The interval between two adjacent first electrodes connected to the first cable is greater than the interval between two adjacent second electrodes connected to the second cable. The three-dimensional DC electrical resistivity data acquisition system is used to implement the three-dimensional DC electrical resistivity data acquisition method as described in any one of claims 1 to 6.

8. The three-dimensional DC resistivity data acquisition system as described in claim 7, characterized in that: The main measuring instrument is a high-density electrical resistivity meter; or / and, The first cable is a large-pitch cable; or / and, The second cable is a centralized cable.

9. The three-dimensional DC resistivity data acquisition system as described in claim 7, characterized in that: The two ends of the first or second test cable are connected to the first cable via cable connectors. When the first or second test cable is composed of multiple second cables connected in series, adjacent second cables are connected in series via cable connectors. The electrode converter is connected to the cable connector.

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