Method and device for combined resistivity induced polarization observation of irregularly distributed holes

Abstract

The application discloses a method and device for irregularly arranged boreholes. The method comprises arranging a first power electrode, a first measuring electrode and a second measuring electrode in three boreholes respectively, and arranging a second power electrode at infinity. During observation, the first power electrode and the first measuring electrode traverse all horizontal positions in the respective borehole synchronously. At each horizontal position, the second measuring electrode moves up and down along the borehole to traverse all electrode positions, and first potential difference data is collected. Then, the three electrodes are moved as a whole in the same direction to traverse all possible borehole combinations, and first potential difference data is collected in each borehole combination. Then, the electrode pair formed by the first power electrode and the first measuring electrode and the second measuring electrode is exchanged, and the borehole combination is traversed in the opposite direction to collect second potential difference data. Based on the method, a corresponding device is also provided. The application has the advantages of flexible borehole arrangement, high efficiency and good imaging quality.

Description

Technical Field

[0001] This invention belongs to the field of applied geophysical exploration technology, and specifically relates to a method and apparatus for multi-pore combined resistivity induced polarization observation of irregularly arranged pores. Background Technology

[0002] High-density resistivity methods, as a geophysical exploration technique based on electrical parameters, are highly sensitive to underground aquifers and are commonly used in fields such as karst, dam seepage, and detection of hazardous water bodies. Vertical drilling allows for the deployment of detection electrodes and cables for cross-hole exploration. This method, by extending the electrodes deep underground and bringing them close to the target, exhibits high sensitivity to deep geological bodies and produces high-resolution imaging results. It is typically used for high-precision imaging of target location, shape, and boundaries.

[0003] However, current mainstream cross-hole detection schemes generally utilize a pair of boreholes, employing a method similar to medical CT scans to perform cross-hole observation. During observation, an electrode array is formed using four electrodes from the two pairs of boreholes, including two power supply electrodes and two measurement electrodes to create a power and measurement circuit. Further, high-density tomographic observation is achieved by moving the electrode array vertically and varying the electrode spacing. However, this method has the following problems: all four electrodes in the array are located in the same vertical plane, resulting in an observation method that can only effectively perceive geological information between two boreholes, with low resolution for lateral anomalies. Even when using multiple boreholes to perform cross-hole observations to obtain multiple profiles, it is difficult to perceive the three-dimensional region between the profiles. During three-dimensional imaging, information loss can easily lead to difficulties in effectively identifying the location, shape, and boundaries of some geological structures.

[0004] To address the aforementioned issues, a method for joint observation using multiple boreholes has been disclosed. The specific steps can be summarized as follows: Four pairs of boreholes are used simultaneously. One electrode is placed in each borehole, along with two power supply electrodes and two measurement electrodes to form a closed loop. A horizontal observation electrode array with through-hole visibility is established. By moving the electrodes up and down, a tomographic scanning observation method is created, enabling effective observation of three-dimensional geological information between boreholes. However, this method still has problems: Firstly, it requires four boreholes. Secondly, the four pairs of boreholes must be arranged in a regular quadrilateral pattern. Reducing the number of boreholes will prevent the effective placement of four electrodes. Non-quadrilateral borehole positions may lead to a decrease in the effective signal and signal-to-noise ratio, or even the inability to obtain reliable observation data. In practical applications, the location of boreholes may be limited by terrain, surface obstacles, and other factors, making it difficult to place them in ideal locations. Furthermore, a larger number of boreholes will increase the detection cost.

[0005] Therefore, there is an urgent need for a multi-hole combined resistivity induced polarization observation method and device that can adapt to irregular borehole distribution, reduce the number of boreholes, and ensure three-dimensional detection effect. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention proposes a method and apparatus for multi-hole combined resistivity induced polarization observation under irregular hole layout conditions. It enables high-resolution observation of three-dimensional resistivity / induced polarization between holes using any three boreholes under irregular hole layout conditions, effectively overcoming the strict limitations of traditional methods on the number and arrangement of boreholes, significantly reducing detection costs and improving data acquisition efficiency.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, the present invention proposes a method for combined resistivity observation of irregularly arranged holes, comprising the following steps: The first power supply electrode, the first measuring electrode, and the second measuring electrode are respectively arranged in the same direction for the three boreholes in the test area, and the second power supply electrode is arranged at infinity. The first power supply electrode and the first measuring electrode synchronously traverse all horizontal plane positions within their respective boreholes. At each horizontal plane position, the second measuring electrode moves up and down along the borehole to traverse all electrode positions. Power is supplied by the first power supply electrode and the second power supply electrode to collect the first potential difference data between the first measuring electrode and the second measuring electrode. The first power supply electrode, the first measuring electrode, and the second measuring electrode are moved as a whole in the same direction to traverse all possible borehole combinations. In each borehole combination, the first power supply electrode and the first measuring electrode are made to synchronously traverse all horizontal plane positions within their respective boreholes. At each horizontal plane position, the second measuring electrode moves up and down along the borehole to traverse all electrode positions and collects the first potential difference data. The positions of the first power supply electrode and the electrode pair consisting of the first measuring electrode and the second measuring electrode are interchanged. All borehole combinations are traversed in the opposite direction to the same direction. In each borehole combination, the first power supply electrode and the first measuring electrode after the interchange are synchronously traversed all horizontal plane positions in their respective boreholes. At each horizontal plane position, the second measuring electrode moves up and down along the borehole to traverse all electrode positions. The second potential difference data between the first power supply electrode and the second measuring electrode after the interchange are collected.

[0008] Furthermore, based on the first potential difference data and the second potential difference data, three-dimensional resistivity and / or excited polarization inversion imaging is performed to obtain a geoelectric model of the three-dimensional region between the boreholes.

[0009] Furthermore, a second power supply electrode is deployed at infinity, specifically: the distance between the second power supply electrode and the three boreholes is at least 5 times the maximum borehole spacing in the test area.

[0010] Furthermore, the interior angles of the triangular region enclosed by the three drill holes are all no greater than 120°, and the three sides are not equal.

[0011] Furthermore, when the first power supply electrode and the first measuring electrode are traversed synchronously, the first power supply electrode and the first measuring electrode always remain in the same horizontal plane.

[0012] Furthermore, when the three boreholes are arranged in an isosceles triangle, the first power supply electrode is positioned at one of the base angles of the isosceles triangle.

[0013] Furthermore, the first power supply electrode, the first measuring electrode, and the second measuring electrode are respectively arranged on the electrode cable in each borehole; and the first power supply electrode, the first measuring electrode, and the second measuring electrode are respectively connected to the ground power supply module and the data acquisition module through cables.

[0014] Furthermore, the electrodes in each borehole are arranged at equal intervals along the vertical direction of the borehole.

[0015] Secondly, the present invention also proposes a multi-hole combined resistivity induced polarization observation device for irregularly arranged holes, comprising: The electrode array module includes a first power supply electrode, a first measuring electrode, and a second measuring electrode arranged in three irregularly distributed boreholes, and a second power supply electrode arranged at infinity. The first power supply electrode, the first measuring electrode, and the second measuring electrode are arranged sequentially in the same direction in the three boreholes. A power supply module is electrically connected to the first power supply electrode and the second power supply electrode, and is used to supply power to the first power supply electrode and the second power supply electrode. The data acquisition module is electrically connected to the first measuring electrode and the second measuring electrode respectively, and is used to acquire the first potential difference data between the first measuring electrode and the second measuring electrode when the first power supply electrode is powered, and to acquire the second potential difference data between the first power supply electrode and the electrode pair composed of the first measuring electrode and the second measuring electrode after the positions of the first power supply electrode and the electrode pair composed of the first measuring electrode and the second measuring electrode are interchanged. The control module is communicatively connected to the power supply module and the data acquisition module, and is used to control the first power supply electrode and the first measuring electrode to synchronously traverse all horizontal positions in their respective boreholes, control the second measuring electrode to move up and down along the borehole to traverse all electrode positions, control the switching of each electrode between borehole combinations, and control the position exchange between the first power supply electrode and the electrode pair composed of the first measuring electrode and the second measuring electrode.

[0016] Furthermore, the control module employs a programmable logic controller, a microcontroller, or an embedded system. Compared with the prior art, the present invention has the following advantages: 1. Overcomes limitations in aperture layout to adapt to complex field conditions. Compared with traditional cross-hole observation methods, this invention establishes a planar three-dimensional sensing system by separately placing the power supply electrode and the measuring electrode in three boreholes. This enables comprehensive and effective detection of the three-dimensional region between boreholes, overcoming the shortcomings of traditional two-hole cross-hole methods, which can only sense two-dimensional profile information between two boreholes and have low resolution for lateral anomalies. Compared with existing multi-hole combined quadrupole electrode arrays, the tripolar electrode array used in this invention only requires three boreholes for implementation, and there is no requirement for the arrangement of the boreholes to be regular quadrilaterals. This allows it to adapt to actual field scenarios with irregular borehole distribution, significantly improving the applicability and flexibility of field detection and reducing detection costs.

[0017] 2. Optimize the extreme running strategy to improve the quality of inversion imaging. This invention proposes a tomographic scanning electrode-running method to complement a triode electrode array. Through a dual-round scanning strategy of "forward traversal + reverse traversal after electrode swapping," it effectively compensates for uneven data distribution caused by irregular borehole layout, ensuring the quality of information perception in the three-dimensional region between boreholes. Inversion imaging results show that the inversion imaging results obtained by the method described in this invention accurately reflect the morphology, location, and resistivity values ​​of geological bodies, with few false anomalies, and the imaging quality is superior to traditional cross-bore observation methods.

[0018] 3. Separate the power supply and measurement electrodes to ensure the quality of the induced polarization signal. This invention places the power supply electrode and the measuring electrode in different boreholes, effectively avoiding the problems of multi-core cable coupling and reuse of power supply and measuring electrodes. During induced polarization observation, this arrangement effectively reduces interference from electrode reuse and cable coupling on the weak induced polarization secondary field signal, significantly improving the signal-to-noise ratio and data quality of the induced polarization detection data.

[0019] 4. Significantly reduces the number of power supply cycles, thus greatly improving data acquisition efficiency. This invention requires fewer power supply electrode pairs and achieves high data acquisition efficiency. Numerical simulation results show that, under the same detection conditions, the number of power supply electrode pairs required by the three-electrode observation method described in this invention is approximately one-tenth that of the traditional Bipole-Bipole observation method, and the data acquisition time can be reduced from several hours to less than ten minutes. In particular, when used with equipment that has multi-channel data acquisition capabilities, only one or a few power supply cycles are needed to simultaneously acquire the potential data of all electrode points, further significantly improving detection and acquisition efficiency.

[0020] 5. Flexible drilling quantity and wide exploration coverage. This invention is applicable to survey areas with any number of boreholes. When there are more than three boreholes in the survey area, three boreholes can be selected to form a group for detection and imaging, realizing flexible observation of multiple borehole combinations in the survey area and effectively improving the borehole utilization rate and detection coverage. Attached Figure Description

[0021] Figure 1 This is a flowchart of the multi-pore combined resistivity induced polarization observation method for irregularly arranged apertures proposed in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the electrode arrangement of a novel triode electrode array suitable for irregularly distributed porous structures, as proposed in Embodiment 1 of the present invention. Figure 3 This is a schematic diagram of the electrode running method applicable to the novel triode electrode array proposed in Embodiment 1 of the present invention; Figure 4 This is a schematic diagram of electrode movement and electrode sequence proposed in Embodiment 1 of the present invention; Figure 5 This is the electric field distribution and electrode arrangement diagram proposed in Embodiment 1 of the present invention; Figure 6 This is a schematic diagram comparing the sensitivity of the novel porous electrode array AMN proposed in Embodiment 1 of the present invention with that of the traditional trans-pore electrode array Bipole-Bipole. Figure 7 This is a schematic diagram of the numerical simulation model design proposed in Embodiment 1 of the present invention; Figure 8 This is a comparison of the imaging results of the novel multi-aperture combined three-electrode observation method proposed in Embodiment 1 of the present invention and the traditional cross-aperture Bipole-Bipole observation method; Figure 9 This is a schematic diagram of the multi-hole combined resistivity induced polarization observation device for irregularly arranged holes proposed in Embodiment 2 of the present invention. Detailed Implementation

[0022] To clearly illustrate the technical features of this solution, the invention will be described in detail below through specific embodiments and in conjunction with the accompanying drawings. The following disclosure provides many different embodiments or examples for implementing different structures of the invention. To simplify the disclosure of the invention, components and arrangements of specific examples are described below. Furthermore, reference numerals and / or letters may be repeated in different examples. This repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. It should be noted that the components illustrated in the drawings are not necessarily drawn to scale. Descriptions of well-known components, processing techniques, and processes are omitted in this invention to avoid unnecessarily limiting the invention.

[0023] Example 1 Embodiment 1 of this invention proposes a multi-hole combined resistivity induced polarization observation method for irregularly distributed boreholes, which is used to solve the problem of how to overcome the strict limitations of existing cross-hole resistivity / induced polarization observation methods on the number and arrangement of boreholes, and realize the effective detection of the three-dimensional region between boreholes under irregularly distributed borehole conditions.

[0024] This invention establishes a novel tripolar electrode array suitable for multi-hole applications, effectively overcoming the strict limitations imposed by previous multi-hole joint observation methods on the number and location of boreholes. This makes the multi-hole electrode array more applicable to irregularly arranged borehole scenarios. Furthermore, the novel tripolar electrode array generates less data, resulting in lower cost and efficiency compared to the quadrupole method, while maintaining consistent imaging quality.

[0025] Figure 1 This is a flowchart of the multi-pore combined resistivity induced polarization observation method for irregularly arranged apertures proposed in Embodiment 1 of the present invention; In step S1, the first power supply electrode, the first measuring electrode, and the second measuring electrode are respectively arranged in the same direction for the three boreholes in the test area, and the second power supply electrode is arranged at infinity. Three boreholes are selected within the survey area. The distribution of these three boreholes can be irregular; they do not need to be arranged in a regular quadrilateral or meet any specific geometric symmetry conditions. When more than three boreholes are located within the survey area, three boreholes are randomly selected from all boreholes to form a group for detection. After detection, the borehole combination is changed and the observation is repeated.

[0026] Figure 2 This is a schematic diagram of the electrode arrangement of a novel triode electrode array suitable for irregularly distributed porous structures, as proposed in Embodiment 1 of the present invention. Within the triangular area enclosed by the three boreholes, three electrodes are sequentially placed in the three boreholes in either a clockwise or counterclockwise direction. The first power supply electrode A is placed in the first borehole, the first measuring electrode M in the second borehole, and the second measuring electrode N in the third borehole. A, M, and N are arranged in either a clockwise or counterclockwise order within the three boreholes. The choice of direction is arbitrary, but once selected (e.g., clockwise), this direction is maintained as the positive direction in all subsequent steps. Figure 2 The right side shows schematic diagrams of AMN counterclockwise and AMN clockwise. For example, in a clockwise direction, they are arranged from A→M→N. Multiple electrodes are arranged vertically within each borehole (only one electrode from each borehole is shown in the diagram as a representative). The electrodes are arranged at equal intervals along the vertical direction of the borehole, and the spacing between adjacent electrodes can be set according to the required detection accuracy. Each electrode is electrically connected via electrode cables laid within the borehole and then led to the ground power supply and data acquisition equipment via multi-core cables.

[0027] Figure 2The dashed arrows in the figure illustrate the electric field distribution range generated by the first power supply electrode A. The arrows indicate that the electric field lines radiate and propagate away from the power supply electrode A, covering the triangular area enclosed by the three boreholes. The figure also uses "V" to mark the potential difference measurement location, i.e., the potential difference data between the first measuring electrode M and the second measuring electrode N is collected. As can be seen from the figure, M and N are located on different equipotential surfaces in the electric field generated by A, and there is a significant potential difference between them. Valid potential difference data can be obtained through the data acquisition module.

[0028] The B electrode is positioned at infinity to prevent its generated electric field from affecting the electric field distribution within the test area. In this invention, infinity means that the distance between the second power supply electrode B and the three boreholes is at least five times the maximum borehole spacing within the test area. The scope of protection of this invention is not limited to the specific values ​​listed in Example 1. Those skilled in the art can make reasonable adjustments while ensuring that the generated electric field does not affect the electric field distribution within the test area.

[0029] When the first power supply electrode and the first measuring electrode are traversed synchronously, the first power supply electrode and the first measuring electrode always remain in the same horizontal plane.

[0030] Multiple electrodes are arranged vertically inside each borehole (e.g.) Figure 3 As shown, the number of electrodes can be determined based on the borehole depth and detection accuracy requirements. Electrodes within each borehole are arranged at equal intervals along the vertical direction of the borehole to ensure uniform sampling of observation data in the depth direction. The electrodes are electrically connected via electrode cables laid within the borehole. Each electrode is led to the ground via an independent conductor in a multi-core cable, connecting to the ground power supply module and the data acquisition module.

[0031] In this invention, the irregularly distributed boreholes should meet the following conditions: First, considering that the effective sensing range of the three boreholes is the triangular region they enclose, the positions of the three boreholes should not form an obtuse triangle with an excessively large angle (e.g., greater than 120°). Furthermore, the three boreholes should not form an equilateral triangle, because when the three boreholes form an equilateral triangle, MN is easily located near the equipotential surface formed by the electric field excited by the first power supply electrode A, resulting in low signal strength and poor signal-to-noise ratio in the collected observation data, making it difficult to use for actual detection.

[0032] When the three holes are distributed in an isosceles triangle or approximately an isosceles triangle, the first power supply electrode A should not be placed at the angle formed by the two isosceles sides, also to avoid MN being distributed near the equipotential surface of the electric field excited by the first power supply electrode A.

[0033] Figure 4This is a schematic diagram of electrode movement and electrode sequence according to Embodiment 1 of the present invention. In a preferred embodiment, the interior angles of the triangular region enclosed by the three boreholes are all no greater than 120°, and the three sides are unequal. When the three boreholes are arranged in an isosceles triangle, the first power supply electrode A should be positioned at one of the base angles of the isosceles triangle. Figure 4 The electric field distribution is given under different power supply electrode positions. When electrode A is located at a right angle formed by the two electrodes (e.g., Figure 4 As shown on the left), when poles M and N are near the equipotential surface, the measured potential difference between poles M and N is 0, indicating that no valid observation data can be obtained; conversely, when pole A is located in the other two positions (such as...), the potential difference between poles M and N is 0, indicating that no valid observation data can be obtained. Figure 4 (As shown in the middle and right sides), the MN electrode can obtain effective observation data. This proves the scientific validity and necessity of the electrode layout rules in step S1.

[0034] In step S2, the first power supply electrode and the first measuring electrode are synchronously traversed all horizontal plane positions in their respective boreholes. At each horizontal plane position, the second measuring electrode moves up and down along the borehole to traverse all electrode positions. Power is supplied by the first power supply electrode and the second power supply electrode to collect the first potential difference data between the first measuring electrode and the second measuring electrode. Combination Figure 3 As shown, this step involves acquiring data for all horizontal plane positions and all electrode depths within the same borehole combination determined in step S1.

[0035] Figure 3 This is a schematic diagram of the electrode running method for the novel triode electrode array proposed in Embodiment 1 of the present invention. The figure shows the electrode layout and electrode running scanning path in three boreholes (from left to right: the first borehole, the second borehole, and the third borehole). The first borehole contains a power supply electrode A1, the second borehole contains two measuring electrodes M1 and M2 (representing the first measuring electrodes at different depths), and the third borehole contains four measuring electrodes N1, N2, N3, and N4 (representing the second measuring electrodes at different depths). The electrodes in each borehole are arranged at equal intervals along the vertical direction of the borehole, and the spacing between adjacent electrodes can be set according to the detection accuracy requirements, for example, 1m.

[0036] First, place the power supply electrode A1 and the measuring electrode M1 at the same horizontal depth within their respective boreholes. For example... Figure 3 As shown, the power supply electrode A1 in the first borehole on the left and the measuring electrode M1 in the second borehole in the middle are in the same horizontal plane (the two are at the same depth). At this time, A1 is located at a certain depth in borehole 1, and M1 is located at the same depth in borehole 2. The two are in the same horizontal plane.

[0037] Then, the second measuring electrode N moves point by point along the borehole (the third borehole) from shallow to deep, sequentially traversing all electrode positions within borehole 3, such as... Figure 3 The arrows for the N electrodes indicate the direction (N1→N2→N3→N4). At each N electrode location, a stable DC current or low-frequency AC current is supplied to the underground medium using power supply electrode A1 and the second power supply electrode B. Simultaneously, the potential difference between the measuring electrode M1 and the second measuring electrode N is collected and recorded as the first potential difference data. Figure 3 The location for potential difference measurement is marked with a "V".

[0038] After completing data acquisition for all N-electrode positions on the current horizontal plane, as follows: Figure 3 As shown, the power supply electrode A1 and the measuring electrode M1 are moved synchronously downwards by one electrode spacing to reach the next horizontal plane (for example, A1 moves to the next electrode position, and M1 moves to the M2 position), keeping A and M always within the same horizontal plane. At the new horizontal plane, the N electrode is again moved point by point along the third borehole from shallow to deep (N1→N2→N3→N4), traversing all electrode positions and collecting the corresponding potential difference data.

[0039] Repeat the above operation until electrode A has traversed all electrode positions in borehole 1 and electrode M has traversed all electrode positions in borehole 2, thus completing the combined observation of all horizontal plane positions and all N electrode positions within the current borehole combination. Figure 3 The “Tomographic Scan” area marked in the figure illustrates the data acquisition coverage area formed by powering the A electrode, moving the N electrode point by point, and measuring the M electrode by fixing it. Figure 3 In the diagram, the label "tomographic scan" spans multiple electrode positions, indicating that the electrode-running method of "A and M traversing the horizontal plane simultaneously, and N traversing the electrodes up and down along the borehole" forms a dense cross-shaped scanning grid in the triangular area between the holes, achieving high-density data coverage of the three-dimensional area between the holes.

[0040] In step S3, the first power supply electrode, the first measuring electrode, and the second measuring electrode are moved as a whole in the same direction to traverse all possible borehole combinations. In each borehole combination, the first power supply electrode and the first measuring electrode are made to synchronously traverse all horizontal plane positions in their respective boreholes. At each horizontal plane position, the second measuring electrode moves up and down along the borehole to traverse all electrode positions and collects the first potential difference data. This step involves moving the same group of three electrodes (first power supply electrode A, first measurement electrode M, and second measurement electrode N) from step S2 as a whole to the next group of boreholes in the same direction (e.g., clockwise) determined in step S1, and repeating the traversal operation of step S2.

[0041] Specifically, when there are more than three boreholes in the survey area, step S2 only completes the data acquisition for one set of borehole combinations (e.g., borehole 1-borehole 2-borehole 3). To obtain a wider three-dimensional coverage, the three electrodes A, M, and N need to be moved as a whole in the same direction to the next set of borehole combinations. For example, A is moved from borehole 1 to borehole 2, M is moved from borehole 2 to borehole 3, and N is moved from borehole 3 to borehole 4 (if borehole 4 exists), forming a new borehole combination (borehole 2-borehole 3-borehole 4).

[0042] In the new drilling combination, repeat all operations of step S2: let A and M synchronously traverse all horizontal plane positions in their respective boreholes, and at each horizontal plane position, N moves up and down along the borehole to traverse all electrode positions and collect the first potential difference data.

[0043] Continue moving in the same direction to the next group of boreholes and performing the same operation until all possible borehole combinations have been traversed. When there are N boreholes in the survey area, three boreholes can be randomly selected to form a group, and the above observations can be performed on each group. For example, when there are four boreholes (borehole 1, borehole 2, borehole 3, and borehole 4) in the survey area, the possible borehole combinations include (borehole 1-borehole 2-borehole 3), (borehole 1-borehole 2-borehole 4), (borehole 1-borehole 3-borehole 4), and (borehole 2-borehole 3-borehole 4), for a total of four combinations. For each borehole combination, perform all operations of step S2.

[0044] In step S4, the positions of the first power supply electrode and the electrode pair consisting of the first measuring electrode and the second measuring electrode are interchanged. All borehole combinations are traversed in the opposite direction to the same direction. In each borehole combination, the first power supply electrode and the first measuring electrode after the interchange are synchronously traversed to all horizontal positions in their respective boreholes. At each horizontal position, the second measuring electrode moves up and down along the borehole to traverse all electrode positions and collects the second potential difference data between the first power supply electrode and the second measuring electrode after the interchange.

[0045] This step involves swapping the positions of the first power supply electrode A with the electrode pair consisting of the first measuring electrode M and the second measuring electrode N, and then retracing all borehole combinations in the opposite direction to the same direction in step S3 (e.g., counterclockwise).

[0046] Specifically, after completing the forward traversal of all borehole combinations in step S3, the roles of the electrodes are interchanged: the original first power supply electrode A (originally located in borehole 1) is swapped with the electrode pair consisting of the first measuring electrode M (originally located in borehole 2) and the second measuring electrode N (originally located in borehole 3). After the swap, the original M electrode (now located in borehole 2) is used as the first power supply electrode, the original A electrode (now located in borehole 1) is used as the first measuring electrode, and the original N electrode (now located in borehole 3) is used as the second measuring electrode.

[0047] Then, all borehole combinations are retraced in the opposite direction to that in step S3 (e.g., if clockwise, counterclockwise). In each borehole combination, the first power supply electrode (original M) and the first measuring electrode (original A) after their positions are swapped are synchronously traversed to all horizontal positions within their respective boreholes. At each horizontal position, the second measuring electrode (original N) moves up and down along the borehole to traverse all electrode positions, and the potential difference between the first power supply electrode and the second measuring electrode after their positions are swapped is collected and recorded as the second potential difference data.

[0048] like Figure 4 As shown, Figure 4 The left side shows that when A is located at the vertex of one side of the two measuring electrodes (i.e., A is located at the vertex of the isosceles triangle), M and N are near the same equipotential surface. At this time, the measured potential difference between M and N approaches zero, and effective observation data cannot be obtained. Figure 4 The middle and right sides show that when A is in one of the other two positions (i.e., A is at the bottom corner), M and N are on different equipotential surfaces, with a significant potential difference between them, allowing for the collection of effective potential difference data. This comparison verifies the scientific validity and necessity of re-observing after the electrodes are swapped in step S4.

[0049] By swapping electrodes and performing reverse traversal in step S4, the uneven data distribution caused by irregular borehole layout can be effectively compensated, ensuring the information perception quality of the three-dimensional region between boreholes. At this point, all tomographic scanning observations are completed, obtaining first and second potential difference data covering all borehole combinations and all horizontal plane positions.

[0050] Figure 5 This is the electric field distribution and electrode arrangement diagram proposed in Embodiment 1 of the present invention. Figure 5 The electric field distribution characteristics under different electrode arrangements are further demonstrated, and the scientific nature of the electrode arrangement rules of the present invention is verified from the perspective of electric field distribution.

[0051] After completing all the above steps, three-dimensional resistivity and / or excited polarization inversion imaging is performed based on the collected first potential difference data and second potential difference data to obtain the geoelectric model of the three-dimensional region between boreholes. Specifically, based on the three-dimensional spatial coordinates of the electrodes in each borehole, an initial resistivity model and / or polarizability model are established. The first potential difference data and second potential difference data are used as observation data input, and the least squares regularized inversion algorithm is used for iterative inversion to output the resistivity distribution model and / or polarizability distribution model of the three-dimensional region between boreholes, which can be used to identify and delineate the location, shape, and boundaries of underground geological bodies.

[0052] Figure 6 This is a schematic diagram comparing the sensitivity of the novel porous electrode array AMN proposed in Embodiment 1 of the present invention with that of the traditional trans-pore electrode array Bipole-Bipole. From... Figure 6 It is evident that the AMN electrode array of this invention exhibits broad and high sensitivity within the triangular region encompassed by the three boreholes, while the Bipole-Bipole array is sensitive only within a limited region between two boreholes, making it difficult to perceive effective information about geological bodies beyond the two-dimensional cross-hole profile. This further verifies the effectiveness and superiority of the observation methods in steps S2 to S4 of this invention in three-dimensional perception between boreholes.

[0053] As an optional implementation, after completing all the above steps, three-dimensional resistivity and / or excited polarization inversion imaging can be performed based on the collected first and second potential difference data to obtain a geoelectric model of the three-dimensional region between boreholes. Specifically, a least-squares regularized inversion algorithm can be used to establish an initial resistivity / polarizability model based on the three-dimensional spatial coordinates of the electrodes inside the borehole. The first and second potential difference data are used as input observation data, and the geoelectric model of the three-dimensional region between boreholes is obtained through iterative inversion.

[0054] Figure 7 This is a schematic diagram of the numerical simulation model design proposed in Embodiment 1 of the present invention. Figure 7 As shown, to verify the technical effect of the present invention, the following numerical simulation model was designed: Four boreholes were set in the survey area in a square distribution, with each borehole being 30m deep. An inclined plate-shaped low-resistivity structure with a thickness of 1m was set up within a depth range of 10-20m underground. The resistivity was set to 200Ω·m, the background resistivity was set to 1000Ω·m, the resistivity of the plate-shaped structure was set to 200Ω·m, and the electrode spacing inside the borehole was set to 1m.

[0055] Numerical simulation data acquisition and inversion imaging were performed using the method described in this invention (triple-electrode observation method) and the traditional trans-aperture Bipole-Bipole method, respectively. The number of inversion iterations was set to three for both methods. After inversion, the root mean square error (RMS) between the predicted and measured data was used to quantitatively evaluate the difference between the inverted geoelectric model and the designed real model. Numerical simulations were performed using the novel multi-aperture electrode array and running-electrode method (AMN) described in this invention, and the traditional trans-aperture Bipole-Bipole method. The simulation data was processed and imaged using conventional least-squares regularized inversion. The advantages and disadvantages of each observation method in terms of data quality were determined by comparing the imaging results with the assumed model.

[0056] It should be noted that when applying the novel porous electrode array and AMN (Ampere Number Method) described in this invention, not all four boreholes are used simultaneously. Instead, three boreholes are selected, and electrodes A, M, and N are sequentially deployed according to the aforementioned electrode placement rules. After completing the tomographic scanning observation, the electrodes are sequentially moved to the next borehole for scanning, following the previously described electrode placement method. Once the AMN has traversed all boreholes, the order of electrodes A, M, and N is reversed according to the previously described rules, and the scan is repeated to traverse all boreholes. When using a traditional cross-hole Bipole-Bipole electrode array, two boreholes must be selected from the four boreholes to deploy the electrodes. Based on the combination principle, the four sides and two diagonals of a square can be selected to form a cross-hole combination. The number of inversion iterations is set to three. After the inversion is completed, the root mean square error (RMS) between the predicted and measured data is used to quantitatively evaluate the difference between the inverted geoelectric model and the designed real model.

[0057] Figure 8 The figures show a comparison of imaging results between the novel multi-pore combined three-electrode observation method proposed in Embodiment 1 of this invention and the traditional cross-pore Bipole-Bipole observation method. (a) shows the imaging result of the novel multi-pore combined three-electrode observation method, and (b) shows the imaging result of the traditional cross-pore Bipole-Bipole observation method. As can be seen from the figures, the imaging results obtained by data inversion using the three-electrode observation method of this invention better reflect the layered structure of the actual geological body. The resistivity value of the low-resistivity structure is approximately 300 Ω·m, which is close to the value of the real model, and the anomaly morphology is continuous with clear boundaries. In contrast, the imaging results of the traditional cross-pore Bipole-Bipole method show many false anomalies. Although it can also show a tilted anomaly similar to the real model, its morphology differs significantly, with voids in the middle. There are also large low-resistivity false anomalies above the inverted imaging area. These problems will affect the geological interpretation based on this imaging result.

[0058] In terms of data volume, the three-electrode observation method requires only 120 pairs of AB power supply electrodes, while the Bipole-Bipole method requires approximately 1500 pairs, significantly more. Assuming that the power supply and discharge of one pair of electrodes takes 4 seconds, and using a multi-channel data acquisition instrument, the potential data of all other electrodes can be acquired in just 1 second, then a single AB electrode pair power supply and discharge and data acquisition operation takes only 5 seconds. Therefore, the three-electrode observation method can complete all data acquisition in just 600 seconds, while the traditional Bipole-Bipole method requires 7500 seconds, far exceeding the three-electrode observation method. Overall, the three-electrode observation method is superior to the traditional cross-aperture observation method in terms of data quality, imaging effect, and detection efficiency.

[0059] The multi-hole joint resistivity induced polarization observation method for irregularly distributed boreholes proposed in Embodiment 1 of this invention enables high-resolution scanning observation of three-dimensional resistivity / induced polarization between boreholes using only three boreholes under arbitrary irregular borehole distribution conditions. This effectively breaks through the strict limitations of traditional methods on the number and arrangement of boreholes, significantly reduces the number of power supply cycles, significantly improves data acquisition efficiency, and ensures the quality of inversion imaging.

[0060] Example 2 Based on the method for induced resistivity observation of irregularly arranged apertures using multi-aperture combined resistivity proposed in Embodiment 1 of the present invention, Embodiment 2 of the present invention also proposes a device for induced resistivity observation of irregularly arranged apertures using multi-aperture combined resistivity. Figure 9 This is a schematic diagram of the multi-hole combined resistivity induced polarization observation device for irregularly arranged holes proposed in Embodiment 2 of the present invention. The device includes: The electrode array module includes a first power supply electrode A, a first measuring electrode M, and a second measuring electrode N arranged in three irregularly distributed boreholes, and a second power supply electrode B arranged at infinity. The first power supply electrode A, the first measuring electrode M, and the second measuring electrode N are arranged sequentially in the same direction in the three boreholes. The spacing between adjacent electrodes can be set according to the detection accuracy requirements (e.g., 1m). Each electrode is connected to the ground power supply module and the data acquisition module via cables.

[0061] A power supply module is electrically connected to the first power supply electrode A and the second power supply electrode B, and is used to supply power to the first power supply electrode and the second power supply electrode. The data acquisition module is electrically connected to the first measuring electrode M and the second measuring electrode N respectively, and is used to acquire the first potential difference data between the first measuring electrode M and the second measuring electrode N when the first power supply electrode A is powered, and to acquire the second potential difference data between the first power supply electrode A and the second measuring electrode N after the positions of the first power supply electrode A and the electrode pair composed of the first measuring electrode M and the second measuring electrode N are interchanged. The control module is communicatively connected to the power supply module and the data acquisition module, and is used to control the first power supply electrode A and the first measuring electrode M to synchronously traverse all horizontal positions in their respective boreholes, control the second measuring electrode N to move up and down along the borehole to traverse all electrode positions, control the switching of each electrode between borehole combinations, and control the position exchange between the first power supply electrode A and the electrode pair composed of the first measuring electrode M and the second measuring electrode N.

[0062] In this invention, the control module is communicatively connected to both the power supply module and the data acquisition module, and is used to control the automated execution of the entire observation process.

[0063] In a preferred implementation, the control module is implemented using a programmable logic controller (PLC), a microcontroller, or an embedded system. It can automatically complete all electrode traversal and switching operations through a preset electrode running program, achieving fully automated data acquisition. The control module also includes a human-machine interface for operators to set parameters such as electrode spacing, traversal speed, power supply current, and power supply time, and to display the current electrode position, data acquisition progress, and measurement data in real time.

[0064] As an optional implementation, the data acquisition module features multi-channel synchronous acquisition, allowing simultaneous acquisition of potential difference data for all measurement electrode pairs during a single power supply to the AB electrode pairs. For example, when 30 electrodes are deployed in each borehole, a single-channel acquisition method would require numerous power supply cycles to complete data acquisition for all electrode combinations, resulting in significant time consumption. However, a multi-channel acquisition method, coupled with automatic switching and acquisition control by the control module, can drastically reduce the number of power supply cycles and acquisition time, improving data acquisition efficiency by several to tens of times.

[0065] In addition, the data acquisition module also has a data storage function, which is used to associate and store the acquired first potential difference data and second potential difference data with the corresponding three-dimensional spatial coordinates of the electrode to establish an observation dataset for subsequent three-dimensional inversion imaging processing.

[0066] The device provided in Embodiment 2 of the present invention corresponds completely to the method described in Embodiment 1, and can realize all the observation steps described in Embodiment 1.

[0067] The description of the relevant parts of the multi-hole combined resistivity induced polarization observation device for irregularly arranged holes provided in Embodiment 2 of this application can be found in the detailed description of the corresponding parts of the multi-hole combined resistivity induced polarization observation method for irregularly arranged holes provided in Embodiment 1 of this application, and will not be repeated here.

[0068] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that the elements inherent in a process, method, article, or apparatus that includes a list of elements are included. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. Additionally, portions of the technical solutions provided in the embodiments of this application that are consistent with the implementation principles of corresponding technical solutions in the prior art have not been described in detail to avoid excessive elaboration.

[0069] While specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art can make other modifications or variations based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A method for combined resistivity observation of irregularly arranged apertures in multi-pore structures, characterized in that, Includes the following steps: The first power supply electrode, the first measuring electrode, and the second measuring electrode are respectively arranged in the same direction for the three boreholes in the test area, and the second power supply electrode is arranged at infinity. The first power supply electrode and the first measuring electrode synchronously traverse all horizontal plane positions within their respective boreholes. At each horizontal plane position, the second measuring electrode moves up and down along the borehole to traverse all electrode positions. Power is supplied by the first power supply electrode and the second power supply electrode to collect the first potential difference data between the first measuring electrode and the second measuring electrode. The first power supply electrode, the first measuring electrode, and the second measuring electrode are moved as a whole in the same direction to traverse all possible borehole combinations. In each borehole combination, the first power supply electrode and the first measuring electrode are made to synchronously traverse all horizontal plane positions within their respective boreholes. At each horizontal plane position, the second measuring electrode moves up and down along the borehole to traverse all electrode positions and collects the first potential difference data. The positions of the first power supply electrode and the electrode pair consisting of the first measuring electrode and the second measuring electrode are interchanged. All borehole combinations are traversed in the opposite direction to the same direction. In each borehole combination, the first power supply electrode and the first measuring electrode after the interchange are synchronously traversed all horizontal plane positions in their respective boreholes. At each horizontal plane position, the second measuring electrode moves up and down along the borehole to traverse all electrode positions. The second potential difference data between the first power supply electrode and the second measuring electrode after the interchange are collected.

2. The method for combined resistivity induced polarization observation of irregularly shaped apertures according to claim 1, characterized in that, Based on the first potential difference data and the second potential difference data, three-dimensional resistivity and / or excited polarization inversion imaging is performed to obtain the geoelectric model of the three-dimensional region between the boreholes.

3. The method for combined resistivity induced polarization observation of irregularly shaped apertures according to claim 1, characterized in that, A second power supply electrode is deployed at infinity, specifically: the distance between the second power supply electrode and the three boreholes is at least 5 times the maximum borehole spacing in the test area.

4. The method for combined resistivity induced polarization observation of irregularly shaped apertures according to claim 1, characterized in that, The interior angles of the triangular region enclosed by the three boreholes are all no greater than 120°, and the three sides are not equal.

5. The method for combined resistivity induced polarization observation of irregularly shaped apertures according to claim 1, characterized in that, When the first power supply electrode and the first measuring electrode are traversed synchronously, the first power supply electrode and the first measuring electrode always remain in the same horizontal plane.

6. The method for combined resistivity induced polarization observation of irregularly arranged holes according to claim 1, characterized in that, When the three boreholes are arranged in an isosceles triangle, the first power supply electrode is positioned at one of the base angles of the isosceles triangle.

7. The method for combined resistivity induced polarization observation of irregularly arranged holes according to claim 1, characterized in that, The first power supply electrode, the first measuring electrode, and the second measuring electrode are respectively arranged on the electrode cable in each borehole; and the first power supply electrode, the first measuring electrode, and the second measuring electrode are respectively connected to the ground power supply module and the data acquisition module through cables.

8. The method for combined resistivity induced polarization observation of irregularly shaped apertures according to claim 1, characterized in that, The electrodes in each borehole are arranged at equal intervals along the vertical direction of the borehole.

9. A multi-hole combined resistivity induced polarization observation device for irregularly arranged holes, characterized in that, include: The electrode array module includes a first power supply electrode, a first measuring electrode, and a second measuring electrode arranged in three irregularly distributed boreholes, and a second power supply electrode arranged at infinity. The first power supply electrode, the first measuring electrode, and the second measuring electrode are arranged sequentially in the same direction in the three boreholes. A power supply module is electrically connected to the first power supply electrode and the second power supply electrode, and is used to supply power to the first power supply electrode and the second power supply electrode. The data acquisition module is electrically connected to the first measuring electrode and the second measuring electrode respectively, and is used to acquire the first potential difference data between the first measuring electrode and the second measuring electrode when the first power supply electrode is powered, and to acquire the second potential difference data between the first power supply electrode and the electrode pair composed of the first measuring electrode and the second measuring electrode after the positions of the first power supply electrode and the electrode pair composed of the first measuring electrode and the second measuring electrode are interchanged. The control module is communicatively connected to the power supply module and the data acquisition module, and is used to control the first power supply electrode and the first measuring electrode to synchronously traverse all horizontal positions in their respective boreholes, control the second measuring electrode to move up and down along the borehole to traverse all electrode positions, control the switching of each electrode between borehole combinations, and control the position exchange between the first power supply electrode and the electrode pair composed of the first measuring electrode and the second measuring electrode.

10. The multi-hole combined resistivity induced polarization observation device for irregularly arranged holes according to claim 9, characterized in that, The control module employs a programmable logic controller, a microcontroller, or an embedded system.

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