Method and device for determining crack of hot dry rock

Abstract

The invention discloses a method and a device for determining a dry hot rock crack, and belongs to the technical field of geothermal resource exploration. According to the method, an electric field signal is transmitted through a transmitting field source, and corresponding apparent resistivity and differential apparent resistivity are determined based on the received electric field signal; according to the difference apparent resistivity isoline profile map and the difference apparent resistivity isoline plane map obtained according to the difference apparent resistivity, the space distribution of the hot dry rock cracks can be visually and accurately determined. Besides, the second electrodes in the controllable emission field source are located at different depth positions in the drill hole, so that the method can be accurately applied to determination of crack distribution at different depth positions, the problem that in the related technology, a determination method for the hot dry rock crack is low in precision is solved, and the effect of improving the precision of the method can be achieved.

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 hot dry rock cracks. Background Art

[0002] Hot dry rock is a high-temperature rock mass within the earth's crust that contains no fluid or very little fluid and 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 rocks adopts 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, and the electric field signals are processed to determine the spatial distribution of cracks in the hot dry rocks.

[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 embodiment of the present application 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 being used in a target area, the target area including a borehole, a transmitting field source, and a plurality of measuring points, the transmitting field source including a first electrode and a second electrode, the first electrode being located on the ground outside the borehole, the second electrode being located inside the borehole, and the plurality of measuring points being located on the ground of the target area;

[0007] The method comprises:

[0008] Acquiring, at the multiple measuring points, multiple electric field signals emitted by the emission 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] According to the multiple differential apparent resistivities, a differential apparent resistivity contour line profile and a differential apparent resistivity contour line plane map of the target area are obtained, wherein the differential apparent resistivity contour line profile map includes differential apparent resistivity contour lines on a profile perpendicular to the ground, and the differential apparent resistivity contour line plane map 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, a plurality of electric field signals emitted by the emission field source when the second electrode is located at different depths in the borehole, comprises:

[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 position;

[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 signal emitted by the emission field source when the second electrode is located at the second depth position is acquired at the multiple measurement 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 a depth and an apparent resistivity in the target area;

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

[0024] Determine the frequency and period of the electric field signal emitted by the emission field source, the frequency of the electric field signal emitted by the emission field source is within the frequency range of the electric field signal reflecting the 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, and the apparent resistivity calculation formula 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 respectively 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 position, 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 line plane diagram 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 line plane diagram is the positions of the multiple measuring points on the multiple measuring lines in a second direction parallel to the ground, and 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 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;

[0038] Determining the spatial distribution information of the hot dry rock cracks in the target area according to 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 the areas where the differential apparent resistivity values ​​are less than the preset values ​​in the differential apparent resistivity contour line profile diagram and the differential apparent resistivity contour line plane diagram and the corresponding depth positions of the second electrodes;

[0040] Determine the spatial distribution information of 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] On the other hand, a device for determining hot dry rock cracks is provided, the device comprising:

[0044] An electric field signal receiving module, used for 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;

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

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

[0047] A differential apparent resistivity determination module is used to perform differential operations on the multiple apparent resistivities respectively to obtain multiple differential apparent resistivities;

[0048] A differential apparent resistivity mapping module, for obtaining a differential apparent resistivity contour line profile and a differential apparent resistivity contour line plane map of the target area according to the multiple differential apparent resistivities, wherein the differential apparent resistivity contour line profile map includes differential apparent resistivity contour lines on a profile perpendicular to the ground and corresponding measuring point positions and corresponding depth positions of the second electrode, and the differential apparent resistivity contour line plane map includes differential apparent resistivity contour lines on a plane perpendicular to the ground and corresponding measuring point positions;

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

[0050] The beneficial effects brought by the technical solution provided by the embodiment of the present application include at least:

[0051] A method for determining hot dry rock cracks is provided. The method transmits an electric field signal through a transmitting field source, and determines the corresponding apparent resistivity and differential apparent resistivity based on the received electric field signal, so that 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 hot dry rock cracks. In addition, the second electrode in the controllable transmitting field source is located at different depths in the borehole, so that it can be accurately applied to the determination of the crack distribution at different depths, which solves the problem of low accuracy of the method for determining hot dry rock cracks in the related art, and can achieve the effect of improving 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 drawings required for use in the description of the embodiments will be briefly introduced below. 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 creative work.

[0053] Figure 1 It 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 is a flow chart of a method for determining hot dry rock cracks provided in an embodiment of the present application;

[0055] Figure 3 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 curve diagram of 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 is an amplitude spectrum curve diagram provided in an embodiment of the present application;

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

[0060] Figure 8 is a curve diagram of 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] Fig. 9 is a differential apparent resistivity profile curve of multiple measuring points provided in an embodiment of the present application;

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

[0063] Fig.11 It is a differential apparent resistivity contour line plane diagram provided in an embodiment of the present application;

[0064] Fig.12 It 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 have shown clear embodiments of the present application, which will be described in more detail later. These drawings and text descriptions are not intended to limit the scope of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0066] In order to make the objectives, technical solutions and advantages of the present application clearer, the implementation methods of the present application will be further described in detail below in conjunction with 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 1It 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, wherein the target area Q1 includes a borehole 11, a transmitting field source 12, and a plurality of measuring points 13, wherein the transmitting field source 12 includes a first electrode A and a second electrode B, wherein the first electrode A is located on the ground outside the borehole 11, and the second electrode B is located at different depth positions within a specified depth range Q2 within the borehole 11, wherein the maximum depth position of the second electrode B is B1, and the minimum depth position of the second electrode B is B2, and the plurality of measuring points 13 are located on the ground of the target area Q1. The borehole 11 may be a borehole of an existing well, and the transmitting field source 12 may transmit an electric field signal, and the electric field signal may be collected at the plurality of measuring points 13, so that the spatial distribution of the hot dry rock cracks within the specified depth range Q2 in the target area Q1 may be determined by the collected electric field signal.

[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 hot dry rock cracks provided by an embodiment of the present application. The method can be used in a target area, the target area 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, the second electrode is located in the borehole, and 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 a plurality of amplitude spectra corresponding to a plurality of electric field signals.

[0071] Step 203: Determine a plurality of apparent resistivities corresponding to a plurality of amplitude spectra.

[0072] Step 204: Perform 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 diagram 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 according to the differential apparent resistivity contour line profile and the differential apparent resistivity contour line plane of the target area.

[0076] In summary, the embodiment of the present application provides a method for determining hot dry rock cracks, which transmits an electric field signal through a transmitting field source, and determines the corresponding apparent resistivity and differential apparent resistivity based on the received electric field signal, so that 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 hot dry rock cracks. In addition, the second electrode in the controllable transmitting field source is located at different depths in the borehole, so that it can be accurately applied to the determination of the crack distribution at different depths, which solves the problem of low accuracy of the method for determining hot dry rock cracks in the related art, and can achieve the effect of improving the accuracy of the method.

[0077] In an embodiment of the present application, a target area may include 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 can be used to receive the electric field signal 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 : is a flow chart 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 a 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 It is a curve diagram of the relationship between depth and apparent resistivity in a target area provided in an embodiment of the present application. Figure 4 The ordinate is the different depth positions, the unit is meter, and the abscissa is the apparent resistivity corresponding to the different depth positions, the unit is ohm·meter. Figure 4 Including the original resistivity data S1 and the resistivity data S2 after forward modeling, the forward modeling software can be used to perform forward modeling calculation on the collected original resistivity data S1 of the target area, 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 according to 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, and 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 by Figure 4 The forward modeled resistivity data S2 is obtained, 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 can be a depth range of 3650 meters to 3950 meters from the ground, wherein the maximum depth position B1 of the second electrode B can be 3950 meters from the ground, and the minimum depth position B2 of the second electrode B can 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 can be calculated respectively by the above frequency calculation formula, so that the frequency range corresponding to the specified depth range can be obtained as 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 respectively by the above-mentioned frequency calculation formula, so as to determine the frequency of the electric field signal emitted by the transmitting field source. 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 in 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 set at different depths in the borehole, and the spacing between adjacent depths can be a specified distance, and for example, the specified distance can be 10 meters. The first electrode cooperates with the second electrode located at different depths in the borehole to transmit an electric field signal. The transmitting field source can transmit multiple electric field signals according to the frequency and period obtained in step 303. The greater the depth of the second electrode, the lower the corresponding electric field signal frequency and the larger the period. The shallower the depth of the second electrode, the higher the corresponding electric field signal frequency and the smaller the period.

[0092] Specifically, obtaining 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) Acquire, at multiple measuring points, an electric field signal emitted by the transmitting field source when the second electrode is located at the first depth position.

[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, an electric field signal emitted by the transmitting field source when the second electrode is located at the second depth position.

[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 spacing between the first depth position and the initial position is the specified distance, and the spacing between the second depth position and the first depth position is the 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 signal received at seven measuring points among the multiple measuring points and time provided in an embodiment of the present application, Figure 5 It reflects the relationship between electric field strength 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 provided by the electric field signal can be used to calculate the amplitude spectrum.

[0101] Step 305: Determine a plurality of amplitude spectra corresponding to a plurality of 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 of the amplitude spectrum can be:

[0103]

[0104] Among them, A i (f) is the amplitude spectrum of the i-th measuring point among the multiple measuring points at frequency f, E(n) is the multiple electric field signals obtained at the multiple measuring points, and E(n) can be Figure 5 The data of the electric field signal provided, N is the number of depth positions of the second electrode. For example, please refer to Figure 6 , Figure 6 It 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 a plurality of apparent resistivities corresponding to the plurality of amplitude spectra.

[0106] The apparent resistivity corresponding to the amplitude spectrum can be determined by the apparent resistivity calculation formula, which 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 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. Exemplarily, the first electrode is located on the ground, the minimum depth position B2 can be 3650 meters from the ground, then r1 can be 3650 meters, 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 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 apparent resistivity calculation of 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 It is an apparent resistivity curve at multiple measuring points provided by an embodiment of the present application, wherein the horizontal axis is the measuring point distance, the vertical axis is the logarithm of the frequency, each curve is the apparent resistivity curve of one measuring point among 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 respectively 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 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 the electrical property changes 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 is a graph of 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, and 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. Fig. 9 , Fig. 9It 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. Fig. 9 Provides differential apparent resistivity at multiple depths within a specified depth range for multiple measuring points. Fig. 9 It can reflect the difference in differential apparent resistivity at multiple depth positions at different measuring points, where the size relationship of the depth position corresponding to each curve is: 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 of step 307, so that the differential apparent resistivity contour line profile and the differential apparent resistivity contour line plane map of the target area can be obtained through the drawing software. The differential apparent resistivity contour line profile map includes the differential apparent resistivity contour lines on the profile perpendicular to the ground, and the differential apparent resistivity contour line plane map includes the differential apparent resistivity contour lines on the plane parallel to the ground.

[0117] For example, please refer to Fig.10 , Fig.10 It 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. Fig.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. Fig.10 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, which may be 0.

[0118] Please refer to Fig.11 , Fig.11 The embodiment of the present application provides a differential apparent resistivity contour line plane diagram. The horizontal axis of the differential apparent resistivity contour line plane diagram 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 line plane diagram 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. Fig.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. Fig.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 according to the differential apparent resistivity contour line profile and the differential apparent resistivity contour line plane of the target area.

[0120] Spatial distribution information of 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, according to the differential apparent resistivity contour profile and differential apparent resistivity contour plane of the target area, the spatial distribution information of the hot dry rock cracks in the target area is determined, including:

[0122] 1) Obtaining the measuring point positions corresponding to the areas where the differential apparent resistivity values ​​are less than the preset values ​​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 Fig.10 and Fig.11 , Fig.10 and Fig.11 In the differential apparent resistivity contour profile and differential apparent resistivity contour plane, the value range of the contour can be between -100 ohm·m and 100 ohm·m, the preset value can be 0 ohm·m, and the area with a negative value of the contour can be determined as an area where the differential resistivity is lower than the preset value ( Fig.10 and Fig.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 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 Fig.10 and Fig.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 embodiment of the present application provides a method for determining hot dry rock cracks, which transmits an electric field signal through a transmitting field source, and determines the corresponding apparent resistivity and differential apparent resistivity based on the received electric field signal, so that 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 hot dry rock cracks. In addition, the second electrode in the controllable transmitting field source is located at different depths in the borehole, so that it can be accurately applied to the determination of the crack distribution at different depths, which solves the problem of low accuracy of the method for determining hot dry rock cracks in the related art, and can achieve the effect of improving the accuracy of the method.

[0127] On the other hand, a device for determining cracks in hot dry rocks is provided, see Fig.12 , Fig.12 1 is a schematic diagram of a device for determining a hot dry rock crack 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 used to determine a plurality of amplitude spectrums corresponding to a plurality of electric field signals;

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

[0131] The differential apparent resistivity determination module 1204 is used to perform differential operations on the multiple apparent resistivities respectively to obtain multiple differential apparent resistivities;

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

[0134] In summary, the embodiment of the present application provides a device for determining hot dry rock cracks. The method transmits an electric field signal through a transmitting field source, and determines the corresponding apparent resistivity and differential apparent resistivity based on the received electric field signal. In this way, the differential apparent resistivity contour line profile and the differential apparent resistivity contour line plane obtained according to the differential apparent resistivity can intuitively and accurately determine the spatial distribution of hot dry rock cracks. In addition, the second electrode in the controllable transmitting field source is located at different depths in the borehole, so that it can be accurately applied to the determination of the crack distribution at different depths, which solves the problem of low accuracy of the method for determining hot dry rock cracks in the related art, and can achieve the effect of improving the accuracy of the method.

[0135] In the present 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 otherwise clearly defined.

[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 only schematic, for example, the division of the units is only a logical function division, and there may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed.

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

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

Claims

1. A method for determining hot dry rock cracks, characterized in that: The method is used in a target area, wherein the target area includes a borehole, a transmitting field source and a plurality of measuring points, wherein the transmitting field source includes a first electrode and a second electrode, wherein 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 emission field source when the second electrode is located at different depths in the borehole; Determining a plurality of amplitude spectra corresponding to the plurality of electric field signals; determining a plurality of apparent resistivities corresponding to the plurality of amplitude spectra; performing differential operations on the plurality of apparent resistivities respectively to obtain a plurality of differential apparent resistivities; According to the multiple differential apparent resistivities, a differential apparent resistivity contour line profile and a differential apparent resistivity contour line plane map of the target area are obtained, wherein the differential apparent resistivity contour line profile map includes differential apparent resistivity contour lines on a profile perpendicular to the ground, and the differential apparent resistivity contour line plane map 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 The step of acquiring, at the plurality of measuring points, a plurality of electric field signals emitted by the emission field source when the second electrode is located at different depths in the borehole comprises: 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 position; 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 signal emitted by the emission field source when the second electrode is located at the second depth position is acquired at the multiple measurement points.

3. The method according to claim 2, characterized in that The controlling the transmitting field source to transmit an electric field signal comprises: Acquiring resistivity data of the target area, wherein the resistivity data of the target area includes a relationship between a depth and an apparent resistivity in the target area; determining a frequency range of an electric field signal reflecting a specified depth range in the target area based on the resistivity data of the target area; Determine the frequency and period of the electric field signal emitted by the emission field source, the frequency of the electric field signal emitted by the emission field source is within the frequency range of the electric field signal reflecting the 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; The transmitting field source is controlled to transmit the electric field signal according to the period.

4. The method according to claim 2, characterized in that: The target area includes a measuring network, the measuring network includes a plurality of measuring lines, each measuring line includes a plurality of measuring points, each measuring point includes a collecting station, and the collecting station is used to receive the electric field signal emitted by the emission field source.

5. The method according to claim 1, characterized in that The determining the apparent resistivity corresponding to the amplitude spectra of the plurality of measuring points comprises: The apparent resistivity corresponding to the amplitude spectrum is determined by the apparent resistivity calculation formula, and the apparent resistivity calculation formula includes: 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.

6. The method according to claim 2, characterized in that The performing differential calculation on the apparent resistivities of the plurality of measuring points respectively to obtain the differential apparent resistivities of the plurality of measuring points comprises: 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)=ρ 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 position, 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.

7. The method according to claim 4, characterized in that The horizontal axis of the differential apparent resistivity contour profile is the positions of a plurality of measuring points on one of the plurality of 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 line plane diagram 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 line plane diagram is the positions of the multiple measuring points on the multiple measuring lines in a second direction parallel to the ground, and the first direction is perpendicular to the second direction.

8. The method according to claim 7, 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 according to 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 the areas where the differential apparent resistivity values ​​are less than the preset values ​​in the differential apparent resistivity contour line profile and the differential apparent resistivity contour line plane map and the corresponding depth positions of the second electrodes; Determine the spatial distribution information of the hot dry rock fractures in the target area.

9. The method according to claim 1, characterized in that: The determining of the amplitude spectrum corresponding to the electric field signal received by the multiple measuring points includes: Performing Fourier transform on the electric field signals received by the multiple measuring points to obtain amplitude spectra corresponding to the electric field signals.

10. A device for determining hot dry rock cracks, characterized in that: The device comprises: An electric field signal receiving module, used for 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; An amplitude spectrum determination module, used to determine a plurality of amplitude spectrums corresponding to the plurality of electric field signals; an apparent resistivity determination module, used to determine a plurality of apparent resistivities corresponding to the plurality of amplitude spectra; A differential apparent resistivity determination module is used to perform differential operations on the multiple apparent resistivities respectively to obtain multiple differential apparent resistivities; A differential apparent resistivity mapping module, for obtaining a differential apparent resistivity contour line profile and a differential apparent resistivity contour line plane map of the target area according to the multiple differential apparent resistivities, wherein the differential apparent resistivity contour line profile map includes differential apparent resistivity contour lines on a profile perpendicular to the ground and corresponding measuring point positions and corresponding depth positions of the second electrode, and the differential apparent resistivity contour line plane map includes differential apparent resistivity contour lines on a plane perpendicular to the ground and corresponding measuring point positions; The fracture distribution determination module is used to determine the spatial distribution information of the hot dry rock fractures in the target area according to the differential apparent resistivity contour line profile and the differential apparent resistivity contour line plane of the target area.

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