Method and device for determining dry hot rock fractures

Abstract

The application discloses a dry hot rock crack determination method and a determination device, and belongs to the technical field of geothermal resource exploration. The method transmits an electric field signal through a transmitting field source, and determines corresponding apparent resistivity and differential apparent resistivity based on the received electric field signal. Thus, the differential apparent resistivity contour profile and the differential apparent resistivity contour plane obtained according to the differential apparent resistivity can intuitively and accurately determine the spatial distribution of the dry hot rock cracks. In addition, the second electrode in the controllable transmitting field source is located at different depth positions in the drill hole, so that it can be accurately applied to the determination of crack distribution at different depth positions, and solves the problem of low accuracy of the dry hot rock crack determination method in the related art, and can realize the effect of improving the accuracy of the method.

Description

Technical Field

[0001] The present application relates to the technical field of geothermal resource exploration, and in particular to a method and device for determining dry hot rock cracks. Background Art

[0002] Hot dry rock is a high-temperature rock mass in the earth's crust that contains no fluid or very little fluid. It can be used as a geothermal resource. The spatial distribution of hot dry rock cracks can provide technical data support for the development of hot dry rock energy.

[0003] A method for determining cracks in hot dry rock uses a transmitting field source to transmit electric field signals. The transmitting field source is located on the ground, and the electric field signals emitted by the transmitting field source are collected by a collection station. The electric field signals are processed to determine the spatial distribution of cracks in the hot dry rock.

[0004] However, since the transmitting field source used in the above method is located on the ground, the electric field signal emitted by it is difficult to accurately determine the distribution of hot dry rock cracks, which leads to the low accuracy of the above method. Summary of the Invention

[0005] The present invention provides a method and device for determining hot dry rock cracks. The technical solution is as follows:

[0006] According to a first aspect of the present application, a method for determining hot dry rock fractures is provided. The method is applied to a target area, the target area including a borehole, a transmitting field source, and a plurality of measuring points. The transmitting field source includes a first electrode and a second electrode. The first electrode is located on the ground outside the borehole, the second electrode is located inside the borehole, and the plurality of measuring points are located on the ground in the target area.

[0007] The method comprises:

[0008] Acquiring, at the multiple measuring points, multiple electric field signals emitted by the transmitting field source when the second electrode is located at different depths in the borehole;

[0009] determining a plurality of amplitude spectra corresponding to the plurality of electric field signals;

[0010] determining a plurality of apparent resistivities corresponding to the plurality of amplitude spectra;

[0011] performing differential operations on the plurality of apparent resistivities respectively to obtain a plurality of differential apparent resistivities;

[0012] Obtaining a differential apparent resistivity contour line profile and a differential apparent resistivity contour line plane of the target area based on the multiple differential apparent resistivities, wherein the differential apparent resistivity contour line profile includes differential apparent resistivity contour lines on a section perpendicular to the ground, and the differential apparent resistivity contour line plane includes differential apparent resistivity contour lines on a plane parallel to the ground;

[0013] The spatial distribution information of the hot dry rock cracks in the target area is determined based on the differential apparent resistivity contour line profile and the differential apparent resistivity contour line plane of the target area.

[0014] Optionally, acquiring, at the multiple measuring points, multiple electric field signals emitted by the transmitting field source when the second electrode is located at different depths in the borehole includes:

[0015] moving the second electrode upward from an initial position to a first depth position with a specified distance as a step length;

[0016] Controlling the transmitting field source to transmit an electric field signal;

[0017] acquiring, at the plurality of measuring points, electric field signals emitted by the emission field source when the second electrode is located at the first depth;

[0018] moving the second electrode upward from the first depth position to a second depth position with the designated distance as a step;

[0019] Controlling the transmitting field source to transmit an electric field signal;

[0020] The electric field signals emitted by the transmitting field source when the second electrode is located at the second depth are acquired at the multiple measuring points.

[0021] Optionally, controlling the transmitting field source to transmit an electric field signal includes:

[0022] Acquiring resistivity data of the target area, wherein the resistivity data of the target area includes a relationship between depth and apparent resistivity in the target area;

[0023] determining, based on the resistivity data of the target area, a frequency range of an electric field signal reflecting a specified depth range in the target area;

[0024] Determining a frequency and a period of an electric field signal emitted by the emission field source, wherein the frequency of the electric field signal emitted by the emission field source is within the frequency range of the electric field signal reflecting a specified depth range in the target area, and the period is the reciprocal of the frequency of the electric field signal emitted by the emission field source;

[0025] The transmitting field source is controlled to transmit the electric field signal according to the period.

[0026] Optionally, the target area includes a measurement network, the measurement network includes multiple measurement lines, each measurement line includes multiple measurement points, each measurement point includes a collection station, and the collection station is used to receive the electric field signal emitted by the emission field source.

[0027] Optionally, determining the apparent resistivity corresponding to the amplitude spectra of the multiple measuring points includes:

[0028] The apparent resistivity corresponding to the amplitude spectrum is determined by the apparent resistivity calculation formula, which includes:

[0029]

[0030] Among them, ρ w is the apparent resistivity, A i (f) is the amplitude spectrum of the i-th measuring point among the multiple measuring points at a frequency of f, r1 is the minimum distance between the first electrode and the second electrode in a direction perpendicular to the ground, and r2 is the maximum distance between the first electrode and the second electrode in a direction perpendicular to the ground.

[0031] Optionally, performing differential calculation on the apparent resistivities of the multiple measuring points to obtain the differential apparent resistivities of the multiple measuring points includes:

[0032] The differential apparent resistivity of the plurality of measuring points is determined by a differential operation formula, wherein the differential operation formula includes:

[0033] Df_ρ w (i) = ρ w (h i )-ρ w (h i-1 );

[0034] Among them, Df_ρ w (i) is the differential apparent resistivity corresponding to the i-th depth position, ρ w (h i ) is the apparent resistivity of the second electrode under the emission field source at the i-th depth position, h i is the i-th depth position, ρ w (h i-1 ) is the apparent resistivity under the emission source when the second electrode is located at the (i-1)th depth, h i-1 is the (i-1)th depth position, and the i-th depth position is adjacent to the (i-1)th depth position.

[0035] Optionally, the horizontal axis of the differential apparent resistivity contour profile is the positions of multiple measuring points on one of the multiple measuring lines, and the vertical axis of the differential apparent resistivity contour profile is the depth position of the second electrode;

[0036] The horizontal axis of the differential apparent resistivity contour map is the positions of the multiple measuring points on the multiple measuring lines in a first direction parallel to the ground, and the vertical axis of the differential apparent resistivity contour map is the positions of the multiple measuring points on the multiple measuring lines in a second direction parallel to the ground, where the first direction is perpendicular to the second direction.

[0037] Optionally, the spatial distribution information of the hot dry rock cracks in the target area includes positions of the hot dry rock cracks in the target area in the first direction, positions of the hot dry rock cracks in the target area in the second direction, and depth positions of the hot dry rock cracks in the target area;

[0038] Determining the spatial distribution information of the hot dry rock cracks in the target area based on the differential apparent resistivity contour line profile and the differential apparent resistivity contour line plane of the target area includes:

[0039] Obtaining the measuring point positions corresponding to areas where the differential apparent resistivity values ​​are less than a preset value in the differential apparent resistivity contour line profile and the differential apparent resistivity contour line plan, and the corresponding depth positions of the second electrodes;

[0040] Determine the spatial distribution information of the hot dry rock fractures in the target area.

[0041] Optionally, determining amplitude spectra corresponding to the electric field signals received by the multiple measuring points includes:

[0042] Performing Fourier transform on the electric field signals received by the multiple measuring points to obtain amplitude spectra corresponding to the electric field signals.

[0043] In another aspect, a device for determining dry hot rock cracks is provided, the device comprising:

[0044] an electric field signal receiving module, configured to acquire, at the plurality of measuring points, a plurality of electric field signals emitted by the transmitting field source when the second electrode is located at different depths in the borehole;

[0045] an amplitude spectrum determination module, configured to determine a plurality of amplitude spectrums corresponding to the plurality of electric field signals;

[0046] an apparent resistivity determination module, configured to determine a plurality of apparent resistivities corresponding to the plurality of amplitude spectra;

[0047] a differential apparent resistivity determination module, configured to perform differential operations on the plurality of apparent resistivities to obtain a plurality of differential apparent resistivities;

[0048] a differential apparent resistivity mapping module, configured to obtain a differential apparent resistivity contour profile and a differential apparent resistivity contour plane of the target area based on the multiple differential apparent resistivities, wherein the differential apparent resistivity contour profile includes differential apparent resistivity contour lines on a section perpendicular to the ground, corresponding measuring point positions, and corresponding depth positions of the second electrode; and the differential apparent resistivity contour plane includes differential apparent resistivity contour lines on a plane perpendicular to the ground, and corresponding measuring point positions;

[0049] The crack distribution determination module is used to determine the spatial distribution information of the hot dry rock cracks in the target area based on the differential apparent resistivity contour line profile and the differential apparent resistivity contour line plane of the target area.

[0050] The beneficial effects of the technical solutions provided in the embodiments of the present application include at least:

[0051] A method for determining hot dry rock fractures is provided. This method transmits electric field signals via a transmitting field source and determines the corresponding apparent resistivity and differential apparent resistivity based on the received electric field signals. The differential apparent resistivity contour profile and differential apparent resistivity contour plan obtained from the differential apparent resistivity can intuitively and accurately determine the spatial distribution of hot dry rock fractures. Furthermore, the second electrode in the controllable transmitting field source is positioned at different depths in the borehole, enabling precise determination of fracture distribution at different depths. This method addresses the low accuracy of related methods for determining hot dry rock fractures and improves the accuracy of the method. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0053] Figure 1 This is a schematic diagram of an application scenario of a method for determining hot dry rock cracks provided in an embodiment of the present application;

[0054] Figure 2 This is a flow chart of a method for determining hot dry rock cracks provided in an embodiment of the present application;

[0055] Figure 3 This is a flow chart of another method for determining hot dry rock cracks provided in an embodiment of the present application;

[0056] Figure 4 is a graph showing the relationship between depth and apparent resistivity in a target area provided in an embodiment of the present application;

[0057] Figure 5 is a graph showing the relationship between electric field signals received at multiple measuring points and time, provided in an embodiment of the present application;

[0058] Figure 6 This is an amplitude spectrum curve diagram provided by an embodiment of the present application;

[0059] Figure 7 This is an apparent resistivity curve diagram at multiple measuring points provided by an embodiment of the present application;

[0060] Figure 8 is a graph showing the relationship between the differential apparent resistivity and depth of one of the multiple measuring points provided in an embodiment of the present application;

[0061] Figure 9 This is a differential apparent resistivity profile curve of multiple measuring points provided in an embodiment of the present application;

[0062] Figure 10 This is a differential apparent resistivity contour profile provided in an embodiment of the present application;

[0063] Figure 11 This is a differential apparent resistivity contour map provided in an embodiment of the present application;

[0064] Figure 12 This is a schematic diagram of a device for determining dry hot rock cracks provided in an embodiment of the present application.

[0065] The above drawings illustrate specific embodiments of the present application, which will be described in more detail below. These drawings and the textual description are not intended to limit the scope of the present application in any way, but rather to illustrate the concepts of the present application to those skilled in the art by reference to specific embodiments. DETAILED DESCRIPTION

[0066] In order to make the objectives, technical solutions and advantages of this application clearer, the implementation methods of this application will be further described in detail below with reference to the accompanying drawings.

[0067] The present application embodiment provides a method for determining hot dry rock cracks, which can be used to determine hot dry rock cracks in a target area. Figure 1 , Figure 1This is a schematic diagram of an application scenario of a method for determining hot dry rock fractures provided in an embodiment of the present application. The target area Q1 includes a borehole 11, a transmitting field source 12, and multiple measuring points 13. The transmitting field source 12 includes a first electrode A and a second electrode B. The first electrode A is located on the ground outside the borehole 11, and the second electrode B is located at different depths within a specified depth range Q2 within the borehole 11. The maximum depth position of the second electrode B is B1, and the minimum depth position of the second electrode B is B2. The multiple measuring points 13 are located on the ground of the target area Q1. The borehole 11 can be an existing well borehole. The transmitting field source 12 can emit electric field signals, and the electric field signals can be collected at the multiple measuring points 13. Therefore, the spatial distribution of the hot dry rock fractures within the specified depth range Q2 in the target area Q1 can be determined based on the collected electric field signals.

[0068] This application embodiment provides a method for determining dry hot rock cracks, please refer to Figure 2 , Figure 2 This is a flow chart of a method for determining dry hot rock fractures provided by an embodiment of the present application. The method can be used in a target area, which includes a borehole, a transmitting field source, and multiple measuring points. The transmitting field source includes a first electrode and a second electrode. The first electrode is located on the ground outside the borehole, and the second electrode is located inside the borehole. The multiple measuring points are located on the ground in the target area. The method includes:

[0069] Step 201: Acquire, at multiple measuring points, multiple electric field signals emitted by a transmitting field source when the second electrode is located at different depths in the borehole.

[0070] Step 202: Determine multiple amplitude spectra corresponding to multiple electric field signals.

[0071] Step 203: Determine multiple apparent resistivities corresponding to the multiple amplitude spectra.

[0072] Step 204 : performing differential operations on the multiple apparent resistivities respectively to obtain multiple differential apparent resistivities.

[0073] Step 205: Obtain a differential apparent resistivity contour line profile and a differential apparent resistivity contour line plane of the target area based on the multiple differential apparent resistivities.

[0074] The differential apparent resistivity contour profile includes differential apparent resistivity contour lines on a profile perpendicular to the ground, and the differential apparent resistivity contour plane diagram includes differential apparent resistivity contour lines on a plane parallel to the ground.

[0075] Step 206: Determine the spatial distribution information of the hot dry rock fractures in the target area based on the differential apparent resistivity contour profile and the differential apparent resistivity contour plane of the target area.

[0076] In summary, the embodiments of the present application provide a method for determining hot dry rock fractures. This method transmits an electric field signal via a transmitting field source and determines the corresponding apparent resistivity and differential apparent resistivity based on the received electric field signal. The differential apparent resistivity contour profile and differential apparent resistivity contour plan obtained based on the differential apparent resistivity can intuitively and accurately determine the spatial distribution of hot dry rock fractures. Furthermore, the second electrode in the controllable transmitting field source is located at different depths in the borehole, allowing it to be accurately applied to determine the distribution of fractures at different depths. This solves the problem of low precision in related art methods for determining hot dry rock fractures and improves the accuracy of the method.

[0077] In an embodiment of the present application, a measurement network may be included in the target area. The measurement network includes multiple measurement lines, each measurement line includes multiple measurement points, and each measurement point includes a collection station. The collection station can be used to receive the electric field signals emitted by the transmission field source. The deployment density of the measurement network can be adjusted according to the size of the target area. For example, the measurement network may include 10 measurement lines, each measurement line may include 100 measurement points, each measurement point includes a collection station. The spacing between adjacent measurement lines may be 50 meters, and the spacing between adjacent measurement points on each measurement line may be 20 meters.

[0078] This application embodiment provides a method for determining dry hot rock cracks, please refer to Figure 3 , Figure 3 Flowchart of another method for determining hot dry rock cracks provided in an embodiment of the present application, the method comprising:

[0079] Step 301: Obtain resistivity data of the target area.

[0080] The resistivity data of the target area may include the relationship between depth and apparent resistivity in the target area. The target area may include the area where hot dry rock fractures are distributed. Please refer to Figure 4 , Figure 4 This is a graph showing the relationship between depth and apparent resistivity in a target area provided in an embodiment of the present application. Figure 4 The vertical axis represents different depth positions in meters, and the horizontal axis represents the apparent resistivity corresponding to different depth positions in ohm-meters. Figure 4 Including the original resistivity data S1 and the resistivity data S2 after forward modeling, the original resistivity data S1 of the collected target area can be forward calculated by forward modeling software, so that the resistivity data S2 after forward modeling can be closer to the actual apparent resistivity value.

[0081] Step 302: Determine the frequency range of the electric field signal reflecting a specified depth range in the target area based on the resistivity data of the target area.

[0082] According to the resistivity data of the target area, the apparent resistivity corresponding to the specified depth range in the target area can be obtained. The frequency range corresponding to the specified depth range can be obtained by the frequency calculation formula. The frequency calculation formula is:

[0083] H=365*(ρ / f) 1 / 2 ;

[0084] Where ρ is the apparent resistivity at one of the depth positions, which can be obtained from Figure 4 The forward modeled resistivity data S2 is provided, where H is the depth and f is the frequency corresponding to the apparent resistivity at one depth.

[0085] For example, please refer to Figure 4 The specified depth range may be a depth range of 3650 meters to 3950 meters from the ground, wherein the maximum depth position B1 of the second electrode B may be 3950 meters from the ground, and the minimum depth position B2 of the second electrode B may be 3650 meters from the ground. The frequency corresponding to the maximum depth position B1 and the frequency corresponding to the minimum depth position B2 may be calculated respectively by the above frequency calculation formula, thereby obtaining a frequency range corresponding to the specified depth range of 62.5 Hz to 0.98 Hz.

[0086] Step 303: Determine the frequency and period of the electric field signal emitted by the emission field source.

[0087] The frequencies corresponding to other depth positions within the specified depth range can be calculated separately by the above-mentioned frequency calculation formula, so that the frequency of the electric field signal emitted by the transmitting field source can be determined. For example, please refer to Table 1, which is a frequency and periodic table of electric field signals emitted by a transmitting field source provided in an embodiment of the present application. The frequency of the electric field signal emitted by the transmitting field source provided in Table 1 is within the frequency range of the electric field signal reflecting the specified depth range in the target area. The period can be calculated by the frequency of the electric field signal emitted by the transmitting field source provided in Table 1, and the period is the reciprocal of the frequency of the electric field signal emitted by the transmitting field source. The greater the detection depth of the second electrode, the lower the corresponding electric field signal frequency, and the shallower the detection depth of the second electrode, the higher the corresponding electric field signal frequency.

[0088] Table 1

[0089] Serial number Cycle(s) Frequency (Hz) 1 0.016 62.500 2 0.026 38.462 3 0.032 31.250 4 0.046 21.739 5 0.064 15.625 6 0.086 11.628 7 0.128 7.812 8 0.168 5.952 9 0.256 3.906 10 0.326 3.067 11 0.400 2.500 12 0.460 2.174 13 0.512 1.953 14 0.680 1.471 15 0.820 1.220 16 1.024 0.977

[0090] Step 304: Acquire, at multiple measuring points, multiple electric field signals emitted by the transmitting field source when the second electrode is located at different depths in the borehole.

[0091] The second electrode can be positioned at different depths in the borehole, with adjacent depths spaced apart by a specified distance, illustratively, 10 meters. The first electrode cooperates with the second electrode positioned at different depths in the borehole to transmit an electric field signal. The transmitting field source can emit multiple electric field signals according to the frequency and period obtained in step 303. A greater depth of the second electrode corresponds to a lower frequency and a longer period of the corresponding electric field signal, while a shallower depth of the second electrode corresponds to a higher frequency and a shorter period of the corresponding electric field signal.

[0092] Specifically, acquiring multiple electric field signals emitted by the transmitting field source when the second electrode is located at different depths in the borehole at multiple measuring points may include:

[0093] 1) The second electrode is moved upward from the initial position to the first depth position with a specified distance as a step length.

[0094] 2) Control the transmitting field source to transmit electric field signals.

[0095] 3) Acquiring, at multiple measuring points, electric field signals emitted by the transmitting field source when the second electrode is located at the first depth.

[0096] 4) Move the second electrode upward from the first depth position to the second depth position with a specified distance as a step.

[0097] 5) Control the transmitting field source to transmit electric field signals.

[0098] 6) Acquire, at multiple measuring points, electric field signals emitted by the transmitting field source when the second electrode is located at the second depth.

[0099] Among them, the initial position of the second electrode can be any depth position of the second electrode within the specified depth range, the distance between the first depth position and the initial position is a specified distance, and the distance between the second depth position and the first depth position is a specified distance. The specified distance can be adjusted according to the geological conditions of the target area. For example, the specified distance can be 10 meters. A smaller specified distance can improve the accuracy of the method.

[0100] For example, please refer to Figure 5 , Figure 5 is a graph showing the relationship between the electric field signals received at seven of the multiple measuring points and time, provided in an embodiment of the present application. Figure 5 It reflects the relationship between electric field intensity and time, which is given by Figure 5 It can be seen that the collected electric field signal is a periodic function. Figure 5 The data of the provided electric field signal can be used to calculate the amplitude spectrum.

[0101] Step 305: Determine multiple amplitude spectra corresponding to the multiple electric field signals.

[0102] The electric field signals received at multiple measuring points can be Fourier transformed to obtain the amplitude spectrum corresponding to the electric field signal. The calculation formula for the amplitude spectrum can be:

[0103]

[0104] Among them, A i (f) is the amplitude spectrum of the i-th measurement point among the multiple measurement points at frequency f, E(n) is the multiple electric field signals obtained at the multiple measurement points, and E(n) can be Figure 5 The data of the electric field signal is provided, and N is the number of depth positions of the second electrode. For example, please refer to Figure 6 , Figure 6 is an amplitude spectrum curve corresponding to multiple electric field signals collected at multiple measuring points provided in an embodiment of the present application, wherein the abscissa is the measuring point number, the ordinate is the amplitude, each curve is the amplitude corresponding to the electric field signal of the same frequency, and the frequency corresponding to each curve can be the frequency of the electric field signal emitted by the emission source provided in Table 1. Figure 6 The amplitude spectrum data provided can be used to calculate the apparent resistivity.

[0105] Step 306: Determine multiple apparent resistivities corresponding to the multiple amplitude spectra.

[0106] The apparent resistivity calculation formula can be used to determine the apparent resistivity corresponding to the amplitude spectrum. The apparent resistivity calculation formula includes:

[0107]

[0108] Among them, ρ w is the apparent resistivity, A i (f) is the amplitude spectrum of the i-th measurement point among multiple measurement points at frequency f, A i (f) can be Figure 6 In the amplitude spectrum data provided, r1 is the minimum distance between the first electrode and the second electrode in the direction perpendicular to the ground, and r2 is the maximum distance between the first electrode and the second electrode in the direction perpendicular to the ground. r1 can be the distance between the first electrode and the second electrode in the direction perpendicular to the ground when the second electrode is at the minimum depth position, and r2 can be the distance between the first electrode and the second electrode in the direction perpendicular to the ground when the second electrode is at the maximum depth position. For example, if the first electrode is located on the ground and the minimum depth position B2 can be 3650 meters from the ground, then r1 can be 3650 meters, and the maximum depth position B1 can be 3950 meters from the ground, then r2 can be 3950 meters. Since the apparent resistivity obtained by the above-mentioned apparent resistivity calculation formula is related to the depth position range of the target area, the apparent resistivity calculation formula can be applied to the calculation of apparent resistivity in different depth ranges, which is conducive to improving the wide applicability and accuracy of the apparent resistivity calculation formula.

[0109] For example, please refer to Figure 7 , Figure 7 This is an apparent resistivity curve at multiple measuring points provided in an embodiment of the present application, wherein the horizontal axis is the distance between the measuring points, the vertical axis is the logarithm of the frequency, each curve is the apparent resistivity curve of one of the multiple measuring points, and the fluctuation of each curve in the horizontal axis direction represents the change of the apparent resistivity measured at the corresponding measuring point with the depth position.

[0110] Step 307: Perform differential operations on the multiple apparent resistivities to obtain multiple differential apparent resistivities.

[0111] The differential apparent resistivity of multiple measuring points can be determined by the differential operation formula, which includes:

[0112] Df_ρ w (i) = ρ w (h i )-ρ w (h i-1 );

[0113] Among them, Df_ρ w (i) is the differential apparent resistivity corresponding to the i-th depth position, ρ w (h i ) is the apparent resistivity of the second electrode under the emission field source at the i-th depth position, h i is the i-th depth position, ρ w (h i-1 ) is the apparent resistivity of the second electrode under the emission source at the (i-1)th depth, h i-1 is the (i-1)th depth position, and the i-th depth position is adjacent to the (i-1)th depth position. The differential apparent resistivity can reflect changes in the electrical properties of the formation. The lower the differential apparent resistivity, the better the conductivity, and the higher the differential apparent resistivity, the worse the conductivity.

[0114] For example, please refer to Figure 8 , Figure 8 This is a graph showing the relationship between the differential apparent resistivity and depth of one of the multiple measuring points provided in an embodiment of the present application, wherein the abscissa is the differential apparent resistivity in ohm-meters, and the ordinate is the depth in meters, where the depth may be the depth position of the second electrode. Figure 8 Provides the differential apparent resistivity of one of the multiple measurement points at multiple depths within the specified depth range. Figure 9 , Figure 9This is a differential apparent resistivity profile curve of multiple measuring points provided in an embodiment of the present application, wherein the horizontal axis is the measuring point number, the vertical axis is the differential apparent resistivity, and the unit is ohm·meter. Each curve is the differential apparent resistivity corresponding to the same depth position. Figure 9 Provides differential apparent resistivity at multiple depths within a specified depth range for multiple measuring points. Figure 9 It can reflect the difference in differential apparent resistivity at multiple depth positions at different measuring points, where the depth position corresponding to each curve has a size relationship of: L1 < L2 < L3 < L4 < L5 < L6 < L7.

[0115] Step 308: Obtain a differential apparent resistivity contour line profile and a differential apparent resistivity contour line plane of the target area based on the multiple differential apparent resistivities.

[0116] The differential apparent resistivity data of multiple measuring points at multiple depths can be obtained according to the differential calculation formula in step 307, so that a differential apparent resistivity contour profile and a differential apparent resistivity contour plane map of the target area can be obtained using mapping software. The differential apparent resistivity contour profile map includes differential apparent resistivity contour lines on a section perpendicular to the ground, and the differential apparent resistivity contour plane map includes differential apparent resistivity contour lines on a plane parallel to the ground.

[0117] For example, please refer to Figure 10 , Figure 10 This is a differential apparent resistivity contour profile provided in an embodiment of the present application. The horizontal axis of the differential apparent resistivity contour profile is the positions of multiple measuring points on one of the multiple measuring lines, and the vertical axis of the differential apparent resistivity contour profile is the depth position of the second electrode. Figure 10 The electrical distribution law of the differential apparent resistivity on the section can be intuitively reflected. The area where the differential apparent resistivity is lower than the preset value corresponds to the location with good conductivity, while the area where the differential apparent resistivity is higher than the preset value corresponds to the location with poor conductivity. Figure 10 The black area C in the figure is the area surrounded by the contour lines. The differential apparent resistivity of the black area C is lower than the preset value, which may be 0.

[0118] Please refer to Figure 11 , Figure 11 The embodiment of the present application provides a differential apparent resistivity contour map. The horizontal axis of the differential apparent resistivity contour map is the position of multiple measuring points on multiple measuring lines in a first direction parallel to the ground, and the vertical axis of the differential apparent resistivity contour map is the position of multiple measuring points on multiple measuring lines in a second direction parallel to the ground. The first direction is perpendicular to the second direction. Figure 11The electrical distribution law of the differential apparent resistivity on the plane can be intuitively reflected. The area where the differential apparent resistivity is lower than the preset value corresponds to the location with good conductivity, and the area where the differential apparent resistivity is higher than the preset value corresponds to the location with poor conductivity. Figure 11 The black area C in the figure is the area surrounded by the contour lines, and the differential apparent resistivity of the black area C is lower than the preset value.

[0119] Step 309: Determine the spatial distribution information of the hot dry rock fractures in the target area based on the differential apparent resistivity contour line profile and the differential apparent resistivity contour line plane of the target area.

[0120] Spatial distribution information of the hot dry rock cracks in the target area, including positions of the hot dry rock cracks in the target area in a first direction, positions of the hot dry rock cracks in the target area in a second direction, and depth positions of the hot dry rock cracks in the target area;

[0121] Specifically, the spatial distribution information of the hot dry rock fractures in the target area is determined based on the differential apparent resistivity contour profile and differential apparent resistivity contour plane of the target area, including:

[0122] 1) Obtaining the measuring point positions corresponding to the areas where the differential apparent resistivity values ​​are less than a preset value in the differential apparent resistivity contour line profile and the differential apparent resistivity contour line plane, and the corresponding depth positions of the second electrodes.

[0123] For example, please refer to Figure 10 and Figure 11 , Figure 10 and Figure 11 In the differential apparent resistivity contour profile and differential apparent resistivity contour plane provided, the contour value range can be between -100 ohm·m and 100 ohm·m, and the preset value can be 0 ohm·m. The area with a negative contour value can be determined as the area where the differential resistivity is lower than the preset value ( Figure 10 and Figure 11 The black area C in the figure), the area where the differential apparent resistivity is lower than the preset value corresponds to a location with good conductivity, so the black area C may be the location where the hot dry rock cracks develop in the target area.

[0124] 2) Determine the spatial distribution information of hot dry rock cracks in the target area.

[0125] For example, please refer to Figure 10 and Figure 11 By obtaining the depth position of the black area C, the position of the black area C in the first direction and the position in the second direction, the spatial distribution information of the hot dry rock cracks in the target area can be determined.

[0126] In summary, the embodiments of the present application provide a method for determining hot dry rock fractures. This method transmits an electric field signal via a transmitting field source and determines the corresponding apparent resistivity and differential apparent resistivity based on the received electric field signal. The differential apparent resistivity contour profile and differential apparent resistivity contour plan obtained based on the differential apparent resistivity can intuitively and accurately determine the spatial distribution of hot dry rock fractures. Furthermore, the second electrode in the controllable transmitting field source is located at different depths in the borehole, allowing it to be accurately applied to determine the distribution of fractures at different depths. This solves the problem of low precision in related art methods for determining hot dry rock fractures and improves the accuracy of the method.

[0127] On the other hand, a device for determining cracks in hot dry rocks is provided. Figure 12 , Figure 12 1 is a schematic diagram of a device for determining dry hot rock cracks provided in an embodiment of the present application. The device 1200 includes:

[0128] The electric field signal receiving module 1201 is used to obtain, at multiple measuring points, multiple electric field signals emitted by the transmitting field source when the second electrode is located at different depths in the borehole;

[0129] An amplitude spectrum determination module 1202 is configured to determine a plurality of amplitude spectrums corresponding to a plurality of electric field signals;

[0130] An apparent resistivity determination module 1203 is configured to determine a plurality of apparent resistivities corresponding to a plurality of amplitude spectra;

[0131] The differential apparent resistivity determination module 1204 is configured to perform differential operations on the plurality of apparent resistivities to obtain a plurality of differential apparent resistivities;

[0132] The differential apparent resistivity mapping module 1205 is configured to obtain a differential apparent resistivity contour profile and a differential apparent resistivity contour plane of the target area based on the multiple differential apparent resistivities. The differential apparent resistivity contour profile includes differential apparent resistivity contour lines on a profile perpendicular to the ground, corresponding measuring point positions, and corresponding depth positions of the second electrode. The differential apparent resistivity contour plane includes differential apparent resistivity contour lines on a plane perpendicular to the ground, and corresponding measuring point positions.

[0133] The fracture distribution determination module 1206 is used to determine the spatial distribution information of the hot dry rock fractures in the target area based on the differential apparent resistivity contour profile and the differential apparent resistivity contour plane of the target area.

[0134] In summary, embodiments of the present application provide a device for determining hot dry rock fractures. This method transmits an electric field signal via a transmitting field source and determines the corresponding apparent resistivity and differential apparent resistivity based on the received electric field signal. The differential apparent resistivity contour profile and differential apparent resistivity contour plan obtained based on the differential apparent resistivity can intuitively and accurately determine the spatial distribution of hot dry rock fractures. Furthermore, the second electrode in the controllable transmitting field source is located at different depths in the borehole, allowing for precise application in determining fracture distribution at different depths. This addresses the low accuracy of related methods for determining hot dry rock fractures and improves the accuracy of the method.

[0135] In this application, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance. The term "plurality" refers to two or more than two, unless expressly limited otherwise.

[0136] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the units is merely a logical functional division. In actual implementation, other division methods may be used, such as combining or integrating multiple units or components into another system, or ignoring or not implementing certain features.

[0137] Those skilled in the art will understand that all or part of the steps to implement the above embodiments may be accomplished by hardware, or may be accomplished by a program to instruct the relevant hardware, and the program may be stored in a computer-readable storage medium, which may be a read-only memory, a disk, or an optical disk, etc.

[0138] The above description is merely an optional embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the scope of protection of the present application.

Claims

1. A method for determining cracks in hot dry rock, characterized in that: The method is used in a target area, the target area includes a borehole, a transmitting field source, and a plurality of measuring points, the transmitting field source includes a first electrode and a second electrode, the first electrode is located on the ground outside the borehole, the second electrode is located inside the borehole, and the plurality of measuring points are located on the ground of the target area; The method comprises: Acquiring, at the multiple measuring points, multiple electric field signals emitted by the transmitting field source when the second electrode is located at different depths in the borehole; the transmitting field source transmitting the electric field signal, including: acquiring resistivity data of the target area, the resistivity data of the target area including the relationship between the depth and the apparent resistivity in the target area; determining, based on the resistivity data of the target area, a frequency range of the electric field signal reflecting a specified depth range in the target area; determining a frequency and a period of the electric field signal emitted by the transmitting field source, the frequency of the electric field signal emitted by the transmitting field source being within the frequency range of the electric field signal reflecting the specified depth range in the target area, and the period being the inverse of the frequency of the electric field signal emitted by the transmitting field source; controlling the transmitting field source to emit the electric field signal according to the period; and determining multiple amplitude spectra corresponding to the multiple electric field signals; Determining a plurality of apparent resistivities corresponding to the plurality of amplitude spectra; the determining of the plurality of apparent resistivities corresponding to the plurality of amplitude spectra comprising: The apparent resistivity corresponding to the amplitude spectrum is determined by the apparent resistivity calculation formula, which includes: r w =A i (f)× ; Among them, ρ w is the apparent resistivity, A i (f) is the amplitude spectrum of the i-th measuring point among the multiple measuring points at frequency f, r1 is the minimum distance between the first electrode and the second electrode in a direction perpendicular to the ground, and r2 is the maximum distance between the first electrode and the second electrode in a direction perpendicular to the ground; performing differential operations on the plurality of apparent resistivities respectively to obtain a plurality of differential apparent resistivities; Obtaining a differential apparent resistivity contour line profile and a differential apparent resistivity contour line plane of the target area based on the multiple differential apparent resistivities, wherein the differential apparent resistivity contour line profile includes differential apparent resistivity contour lines on a section perpendicular to the ground, and the differential apparent resistivity contour line plane includes differential apparent resistivity contour lines on a plane parallel to the ground; The spatial distribution information of the hot dry rock cracks in the target area is determined based on the differential apparent resistivity contour line profile and the differential apparent resistivity contour line plane of the target area.

2. The method according to claim 1, characterized in that Acquiring, at the multiple measuring points, multiple electric field signals emitted by the transmitting field source when the second electrode is located at different depths in the borehole, includes: moving the second electrode upward from an initial position to a first depth position with a specified distance as a step length; Controlling the transmitting field source to transmit an electric field signal; acquiring, at the plurality of measuring points, electric field signals emitted by the emission field source when the second electrode is located at the first depth; moving the second electrode upward from the first depth position to a second depth position with the designated distance as a step; Controlling the transmitting field source to transmit an electric field signal; The electric field signals emitted by the transmitting field source when the second electrode is located at the second depth are acquired at the multiple measuring points.

3. The method according to claim 2, characterized in that The target area includes a measurement network, the measurement network includes multiple measurement lines, each measurement line includes multiple measurement points, each measurement point includes a collection station, and the collection station is used to receive the electric field signal emitted by the emission field source.

4. The method according to claim 2, characterized in that The performing differential calculation on the apparent resistivities of the plurality of measuring points to obtain the differential apparent resistivities of the plurality of measuring points includes: The differential apparent resistivity of the plurality of measuring points is determined by a differential operation formula, wherein the differential operation formula includes: Df_r w (i)=p w (h) i )-r w (h) i-1 ); Among them, Df_ρ w (i) is the differential apparent resistivity corresponding to the i-th depth position, ρ w (h i ) is the apparent resistivity of the second electrode under the emission field source at the i-th depth position, h i is the i-th depth position, ρ w (h i-1 ) is the apparent resistivity under the emission source when the second electrode is located at the (i-1)th depth, h i-1 is the (i-1)th depth position, and the i-th depth position is adjacent to the (i-1)th depth position.

5. The method according to claim 3, characterized in that The horizontal axis of the differential apparent resistivity contour profile is the positions of multiple measuring points on one of the multiple measuring lines, and the vertical axis of the differential apparent resistivity contour profile is the depth position of the second electrode; The horizontal axis of the differential apparent resistivity contour map is the positions of the multiple measuring points on the multiple measuring lines in a first direction parallel to the ground, and the vertical axis of the differential apparent resistivity contour map is the positions of the multiple measuring points on the multiple measuring lines in a second direction parallel to the ground, where the first direction is perpendicular to the second direction.

6. The method according to claim 5, characterized in that The spatial distribution information of the hot dry rock cracks in the target area includes the positions of the hot dry rock cracks in the target area in the first direction, the positions of the hot dry rock cracks in the target area in the second direction, and the depth positions of the hot dry rock cracks in the target area; Determining the spatial distribution information of the hot dry rock cracks in the target area based on the differential apparent resistivity contour line profile and the differential apparent resistivity contour line plane of the target area includes: Obtaining the measuring point positions corresponding to areas where the differential apparent resistivity values ​​are less than a preset value in the differential apparent resistivity contour line profile and the differential apparent resistivity contour line plan, and the corresponding depth positions of the second electrodes; Determine the spatial distribution information of the hot dry rock fractures in the target area.

7. The method according to claim 1, characterized in that The determining of a plurality of amplitude spectra corresponding to the plurality of electric field signals comprises: Performing Fourier transform on the electric field signals received by the multiple measuring points to obtain amplitude spectra corresponding to the electric field signals.

8. A device for determining cracks in hot dry rocks, characterized in that: The device is used to perform the method for determining hot dry rock fractures according to any one of claims 1 to 7; the device comprises: an electric field signal receiving module, configured to obtain, at the multiple measuring points, multiple electric field signals emitted by the transmitting field source when the second electrode is located at different depths in the borehole; the transmitting field source transmitting the electric field signal, comprising: obtaining resistivity data of the target area, the resistivity data of the target area including a relationship between depth and apparent resistivity in the target area; determining, based on the resistivity data of the target area, a frequency range of the electric field signal reflecting a specified depth range in the target area; determining a frequency and a period of the electric field signal emitted by the transmitting field source, the frequency of the electric field signal emitted by the transmitting field source being within the frequency range of the electric field signal reflecting the specified depth range in the target area, and the period being the inverse of the frequency of the electric field signal emitted by the transmitting field source; and controlling the transmitting field source to emit the electric field signal according to the period; an amplitude spectrum determination module, configured to determine a plurality of amplitude spectrums corresponding to the plurality of electric field signals; The apparent resistivity determination module is configured to determine a plurality of apparent resistivities corresponding to the plurality of amplitude spectra; the determining of the plurality of apparent resistivities corresponding to the plurality of amplitude spectra includes: The apparent resistivity corresponding to the amplitude spectrum is determined by the apparent resistivity calculation formula, which includes: r w =A i (f)× ; Among them, ρ w is the apparent resistivity, A i (f) is the amplitude spectrum of the i-th measuring point among the multiple measuring points at frequency f, r1 is the minimum distance between the first electrode and the second electrode in a direction perpendicular to the ground, and r2 is the maximum distance between the first electrode and the second electrode in a direction perpendicular to the ground; a differential apparent resistivity determination module, configured to perform differential operations on the plurality of apparent resistivities to obtain a plurality of differential apparent resistivities; a differential apparent resistivity mapping module, configured to obtain a differential apparent resistivity contour profile and a differential apparent resistivity contour plane of the target area based on the multiple differential apparent resistivities, wherein the differential apparent resistivity contour profile includes differential apparent resistivity contour lines on a section perpendicular to the ground, corresponding measuring point positions, and corresponding depth positions of the second electrode; and the differential apparent resistivity contour plane includes differential apparent resistivity contour lines on a plane perpendicular to the ground, and corresponding measuring point positions; The crack distribution determination module is used to determine the spatial distribution information of the hot dry rock cracks in the target area based on the differential apparent resistivity contour line profile and the differential apparent resistivity contour line plane of the target area.

Images