Crack opening correction method based on electrical imaging based on image crack segmentation and selection

Abstract

The present invention discloses a method for correcting electrical imaging fracture aperture based on image fracture segmentation and selection. The method comprises the following steps: processing natural gamma logging data of fracture development sections and electrical imaging image data of fractures to obtain natural gamma eigenvalues ​​of the fracture development sections and image fracture apertures; obtaining actual fracture apertures based on actual core fracture photographs; performing a first fracture correction based on the natural gamma eigenvalues ​​of the core fracture development sections, the software fracture apertures, and the image fracture apertures; finally, determining a second correction formula based on the actual fracture apertures and the image fracture apertures, and performing a second correction on the first fracture correction result. The proposed secondary fracture aperture correction method has high correction accuracy and only requires 8-20 electrical imaging images of fractures and actual core fracture photographs to correct a large number of fracture apertures calculated by commercial software.

Description

Technical Field

[0001] The present invention belongs to the technical field of geological exploration, and in particular relates to an electrical imaging crack opening correction method based on image crack segmentation and selection. Background Art

[0002] In geological exploration, oil and gas exploration and development, geotechnical engineering, and many other fields closely related to Earth science, natural fractures are of great significance for analyzing geological tectonic movements, evaluating the reservoir and seepage characteristics of oil and gas resources, predicting the effects of hydraulic fracturing expansion, and predicting slope stability. Fracture aperture, a key parameter reflecting the development of fractures within rocks, has a direct impact on the construction of geological models, the formulation of oil and gas resource development strategies, and the assessment of geotechnical engineering safety. Currently, the primary method for calculating fracture aperture is based on electrical imaging logging, performed using log processing and interpretation software (such as Techlog and Ciflog). While this type of software offers the advantage of batch operation and time-saving fracture parameter calculation modules, it also has a significant disadvantage: fracture aperture calculations are often overstated. Depending on the formation type, the error between the calculated fracture aperture and the actual fracture aperture can be several or even dozens of times greater. This significant error severely undermines the application value of fracture aperture data. Therefore, a fracture aperture correction method is urgently needed to accurately calibrate the fracture aperture calculated by commercial analysis software. Summary of the Invention

[0003] To overcome the above-mentioned shortcomings, an electrical imaging fracture aperture correction method based on image fracture segmentation and selection is proposed. The fracture aperture secondary correction method proposed in the present invention can perform more accurate fracture aperture correction. By linking electrical imaging data with actual core fracture aperture, the accuracy of correction is improved. Only electrical imaging images of 8-20 fractures and actual core fracture photos are needed to correct a large number of fracture apertures calculated by commercial software.

[0004] To achieve the above objectives, the present invention employs a technical solution: providing a method for correcting electrical imaging fracture aperture based on image fracture segmentation and selection. The specific steps are as follows: S1, data acquisition: obtaining from analysis software the initial fracture aperture, natural gamma-ray logging data of the fracture development section, electrical imaging images of the fractures, and actual core fracture photographs corresponding to the depth of the electrical imaging logging images;

[0005] S2, data processing: S2.1 Obtain the gamma ray characteristic value of the fracture development section from the natural gamma ray logging data; S2.2 Process the electrical imaging image of the fracture to obtain the image fracture aperture; S2.3 Obtain the actual fracture aperture based on the actual core fracture image;

[0006] S3, first correction: Fractures are classified according to the natural gamma ray eigenvalues ​​of the fracture development segment, and the first crack correction is performed by combining the initial crack opening and the image crack opening. The accuracy of the initial crack opening is improved to be close to that of the image crack opening, and the first correction result is obtained;

[0007] S4, second correction: Based on the actual crack opening and the image crack opening, the first correction result is equated with the image crack opening to perform a second data correction of the crack opening, and the accuracy of the initial crack opening is corrected to be the same as the actual crack opening to obtain the second correction result.

[0008] According to the electrical imaging fracture opening correction method based on image fracture segmentation and selection described in the present invention, its further preferred technical solution is: S2.1 specific steps are: processing the natural gamma logging data of the fracture development section, and using a single eigenvalue to represent the natural gamma value of the fracture development section.

[0009] According to the electrical imaging crack opening correction method based on image crack segmentation and selection of the present invention, a further preferred technical solution is: obtaining the natural gamma eigenvalue of the crack development section includes two steps:

[0010] a. Use the half-width method to read the natural gamma logging data of the fracture development section, and read the natural gamma value in 0.1m intervals;

[0011] b. Calculate the natural gamma ray characteristic value of the fracture development section using formula (1)

[0012] (1)

[0013] Where: GR i is the natural gamma logging data of the fracture development section, where i=1,2,3,…,n; GR eigen is the natural gamma ray characteristic value of the fracture development section.

[0014] According to the electrical imaging crack opening correction method based on image crack segmentation and selection of the present invention, a further preferred technical solution is: step S2.2 includes three steps:

[0015] a. In the electrical imaging image of the crack, draw the R, G, and B grayscale histograms of a region containing only the crack. The R grayscale histogram of this region will show a multimodal distribution. The grayscale value of the lowest point between the two lowest grayscale peaks is used as the crack grayscale threshold.

[0016] b. According to formula (2), the electrical imaging image of the crack is segmented to obtain the electrical imaging crack segmentation image

[0017] (2)

[0018] Where: src is the image gray value matrix; thresh is the crack grayscale threshold; G Fiss Segmentation images for electrical imaging cracks;

[0019] c. Randomly select four sampling points of the crack in the electrical imaging crack segmentation image, measure the crack opening at the four sampling points, and calculate the image crack opening using formula (3):

[0020] (3)

[0021] Where: l is the diameter of the well; H j is the crack opening at the sampling point, where j = 1, 2, 3, 4; L is the width of the electro-imaging image; H Fiss-image is the image crack opening; the unit is mm.

[0022] According to the electrical imaging fracture opening correction method based on image fracture segmentation and selection of the present invention, a further preferred technical solution is: in S2.3, in order to ensure that there is a clear and accurate reference object in the actual core fracture photo, the fracture opening at four sampling points in the actual core fracture photo and the size of the reference object are measured, and the actual size of the reference object is determined at the same time. Finally, the actual fracture opening in the core photo is calculated according to formula (4):

[0023] (4)

[0024] Where: H photo-i is the crack photo opening, where =1, 2, 3, 4; L photo is the reference image size; L actual is the actual size of the reference object; H actual is the actual crack opening; the unit is mm.

[0025] According to the electrical imaging crack opening correction method based on image crack segmentation and selection of the present invention, a further preferred technical solution is: Step S3 is specifically:

[0026] S3.1, Determination of the first correction formula:

[0027] The first correction formula is determined based on the natural gamma ray characteristic value of the fracture development section, the initial fracture aperture, and the image fracture aperture. It is divided into the following three steps:

[0028] a. Based on the initial crack opening and the image crack opening, the opening ratio is calculated using formula (5):

[0029] (5)

[0030] Where: H Fiss-eigen is the initial crack opening; H Fiss-image is the image crack opening; H com is the ratio of opening degree; the unit in the formula is mm;

[0031] b. Prepared based on the ratio of opening and the natural gamma ray characteristic value of the crack development section GR eigen ~ H com The intersection diagram is used to establish the fitting trend line by power function fitting, as shown in formula (6):

[0032] (6)

[0033] Where: a 1 、 b 1 is the fitting coefficient;

[0034] c. According to the initial crack opening and the fitting trend line formula (6), determine the first correction formula (7)

[0035] (7)

[0036] Where: H corr-1 is the first calibration result;

[0037] S3.2, First Correction of Crack Data

[0038] The initial crack opening is substituted into formula (7) to realize the first data correction of the crack opening. Through the first crack data correction, the accuracy of the initial crack opening can be improved to be close to the accuracy of the image crack opening.

[0039] According to the electrical imaging crack opening correction method based on image crack segmentation and selection of the present invention, a further preferred technical solution is: Step S4 is specifically:

[0040] S4.1, Determination of the Second Correction Formula:

[0041] Based on the image crack opening and the actual crack opening, the second correction formula is determined in the following three steps:

[0042] a. Select crack data that has both image crack opening and actual crack opening corresponding to each other, and calculate the difference in opening using formula (8)

[0043] (8)

[0044] Where: H Fiss-image is the image crack opening; H actual is the actual crack opening; H diff is the difference in opening degree;

[0045] b. Create based on the difference in opening and the image crack opening H Fiss-image ~ H diff The intersection diagram is used to establish the fitting trend line through logarithmic fitting, as shown in formula (9):

[0046] (9)

[0047] Where: H Fiss-image is the image crack opening; a 2 、 b 2 is the fitting coefficient; H diff is the difference in opening degree;

[0048] c. According to the image crack opening and the fitting trend line formula (9), determine the second correction formula (10)

[0049] (10)

[0050] Where: H corr-2 is the second calibration result; H Fiss-image is the image crack opening; H diff is the difference in opening degree;

[0051] S4.2, Second correction of crack data:

[0052] The first correction result is equivalent to the image crack opening and is substituted into formula (10) to achieve the second data correction of the crack opening, and the accuracy of the initial crack opening is corrected to be the same as the actual crack opening.

[0053] Compared with the prior art, the technical solution of the present invention has the following advantages / benefits:

[0054] 1. The secondary crack opening correction method proposed in the present invention can correct the crack opening more accurately.

[0055] 2. Improve the accuracy of correction by using electrical imaging data and actual core fracture opening.

[0056] 3. Only 8-20 electrical imaging images of cracks and photos of actual core cracks are needed to correct a large number of crack openings calculated by commercial software. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0058] Figure 1 This is a flow chart of the electrical imaging crack opening correction method based on image crack segmentation and selection of the present invention.

[0059] Figure 2 It is a schematic diagram of the application of correction data of the method for correcting the crack opening degree of electrical imaging based on image crack segmentation and selection according to the present invention.

[0060] Figure 3 It is a schematic diagram of data processing of electrical imaging crack development segments based on image crack segmentation and selected electrical imaging crack opening correction method of the present invention.

[0061] Figure 4 It is a schematic diagram of crack area segmentation of an electrical imaging image based on image crack segmentation and the selected electrical imaging crack opening correction method of the present invention.

[0062] Figure 5 It is a schematic diagram of measuring actual fracture opening from core photographs based on image fracture segmentation and the selected electrical imaging fracture opening correction method of the present invention.

[0063] Figure 6 This is a schematic diagram of the first correction of crack data based on the image crack segmentation and selected electrical imaging crack opening correction method of the present invention.

[0064] Figure 7 7 (a) is the crack data with image crack opening and actual crack opening based on the image crack segmentation and selected electrical imaging crack opening correction method of the present invention; 7 (b) is Figure 7 (a) Corresponding intersection plot.

[0065] Figure 8 It is a schematic diagram of obtaining natural gamma ray characteristic values ​​of fracture development sections by processing natural gamma ray logging data of fracture development sections in Example 2 of the present invention.

[0066] Figure 9 This is a schematic diagram of crack opening obtained by processing an electrical imaging image of a crack in Example 2 of the present invention.

[0067] Figure 10 This is a schematic diagram of measuring actual crack opening by processing actual core crack photos in Example 2 of the present invention.

[0068] Figure 11 This is a schematic diagram of determining the first correction formula in Example 2 of the present invention.

[0069] Figure 12 2 is a schematic diagram showing the structure of determining the second correction formula in Example 2 of the present invention.

[0070] Figure 13 This is an electrical imaging picture of crack 1 in Table 1 of Example 2 of the present invention.

[0071] Figure 14 This is an electrical imaging picture of crack 2 in Table 1 of Example 2 of the present invention.

[0072] Figure 15 This is an electrical imaging picture of crack 3 in Table 1 of Example 2 of the present invention.

[0073] Figure 16 This is an electrical imaging picture of crack 4 in Table 1 of Example 2 of the present invention.

[0074] Figure 17 This is an electrical imaging picture of the crack 10 in Table 1 of Example 2 of the present invention.

[0075] Figure 18 This is an electrical imaging picture of the crack 11 in Table 1 of Example 2 of the present invention.

[0076] Figure 19 This is an electrical imaging picture of the crack 12 in Table 1 of Example 2 of the present invention.

[0077] Figure 20 This is an electrical imaging picture of the crack 23 in Table 1 of Example 2 of the present invention.

[0078] Figure 21This is an electrical imaging picture of the crack 24 in Table 1 of Example 2 of the present invention.

[0079] Figure 22 This is an electrical imaging picture of the crack 25 in Table 1 of Example 2 of the present invention. DETAILED DESCRIPTION

[0080] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention are clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. Therefore, the detailed description of the embodiments of the present invention provided below is not intended to limit the scope of the claimed invention, but merely represents selected embodiments of the present invention.

[0081] Example 1:

[0082] like Figure 1 As shown in FIG, a method for correcting crack opening degree of electrical imaging based on image crack segmentation and selection is shown. The specific operation is as follows: S1, obtaining data: obtaining the initial crack opening degree ( H Fiss-eigen )、Natural gamma logging data of fracture development section( GR i )、Electrical imaging of cracks( G g ), and the electrical imaging pictures of the cracks ( G g ) actual core fracture photos corresponding to the depth ( G a );

[0083] S2, data processing: S2.1 Obtain the gamma ray characteristic value of the fracture development section from the natural gamma ray (GR) logging data; S2.2 Process the electrical imaging image of the fracture to obtain the image fracture aperture; S2.3 Obtain the actual fracture aperture based on the actual core fracture image;

[0084] The specific steps of S2.1 are: processing the natural gamma logging data of the fracture development section, and using a single characteristic value to represent the natural gamma value of the fracture development section.

[0085] The calculation of the natural gamma eigenvalue of the fracture development section includes two steps:

[0086] a. Use the half-width method to read the natural gamma ray (GR) logging data of the fracture development section ( Figure 3 a, b) Read the natural gamma value in 0.1m intervals GR i(i=1,2,3,…,n);

[0087] b. Calculate the natural gamma characteristic value of the fracture development section using formula (1) Figure 3 c)

[0088] (1)

[0089] Where: GR i is the natural gamma logging data of the fracture development section, where i=1,2,3,…,n; GR eigen is the natural gamma ray characteristic value (API) of the fracture development section.

[0090] Step S2.2 includes three steps: image processing to obtain the electrical imaging image of the crack opening degree in the crack. G g Based on ( Figure 4 a):

[0091] a. For one of the electrical imaging images of the crack (referring to a selected area, other images or other areas of the same image will be selected at the same time for the same processing to ensure data diversity and result accuracy) that only contains the crack area, draw the R, G, B grayscale histogram of the area ( Figure 4 b) The R grayscale histogram of the area will show a multi-peak distribution. The grayscale value of the lowest point between the two peaks with the lowest grayscale values ​​is used as the crack grayscale threshold. thresh ( Figure 4 c);

[0092] b. According to formula (2), the electrical imaging image of the crack is segmented to obtain the electrical imaging crack segmentation image

[0093] (2)

[0094] Where: src is the image gray value matrix; thresh is the crack grayscale threshold; G Fiss Segmentation images for electrical imaging cracks;

[0095] c. Crack segmentation image in electro-imaging G Fiss Four sampling points of the crack are randomly selected and the crack opening at the four sampling points is measured. H j (j=1, 2, 3, 4) Figure 4 c), the image crack opening is calculated by formula (3) H Fiss-image

[0096] (3)

[0097] Where: l is the diameter of the well; H j is the crack opening at the sampling point, where j = 1, 2, 3, 4; L is the width of the electro-imaging image; H Fiss-image is the image crack opening; the unit is mm.

[0098] In S2.3, the actual fracture opening degree should be measured by core photographs. G a There are clear and accurate reference objects in the core. G a The opening of the four sampling points of the middle crack H photo-i (i=1, 2, 3, 4) and the reference image size L photo ( Figure 5 ), and determine the actual size of the reference object L actual Finally, the actual crack opening in the core photo is calculated according to formula (4):

[0099] (4)

[0100] Where: H photo-i is the crack photo opening, where =1, 2, 3, 4; L photo is the reference image size; L actual is the actual size of the reference object; H actual is the actual crack opening; the unit is mm.

[0101] S3, first correction: Perform the first crack correction based on the natural gamma ray characteristic value of the crack development section, the initial crack opening, and the image crack opening to obtain the first correction result, so that the accuracy of the initial crack opening is close to that of the image crack opening;

[0102] Step S3 is specifically as follows:

[0103] S3.1, Determination of the first correction formula:

[0104] The first correction formula is determined based on the natural gamma ray characteristic value of the fracture development section, the initial fracture aperture, and the image fracture aperture. It is divided into the following three steps:

[0105] a. Based on the initial crack opening and the image crack opening, the opening ratio is calculated using formula (5):

[0106] (5)

[0107] Where: H Fiss-eigen is the initial crack opening; H Fiss-image is the image crack opening; H com is the ratio of the opening degree; the unit in the formula is mm;

[0108] b. Prepared based on the ratio of opening and the natural gamma ray characteristic value of the crack development section GR eigen ~ H com Intersection diagram ( Figure 6 a) Establish a fitting trend line by power function fitting, as shown in formula (6)

[0109] (6)

[0110] Where: a 1 、 b 1 is the fitting coefficient;

[0111] c. According to the initial crack opening and the fitting trend line formula (6), determine the first correction formula (7) ( Figure 6 b)

[0112] (7)

[0113] Where: H corr-1 is the first calibration result;

[0114] S3.2, First Correction of Crack Data

[0115] Substitute the initial crack opening into formula (7) to obtain the first correction result, and realize the first data correction of crack opening ( Figure 6 b) Through the first crack data correction, the accuracy of the initial crack opening can be improved to be close to the accuracy of the image crack opening.

[0116] S4, second correction: The second correction formula is obtained using the actual crack opening and the image crack opening to achieve the correction of the image crack opening to the actual crack opening. The first correction result is then equated with the image crack opening and substituted into the correction formula for the second crack correction to obtain the second correction result, so that the accuracy of the first correction result is close to that of the actual crack opening.

[0117] Step S4 is specifically as follows:

[0118] S4.1, Determination of the Second Correction Formula:

[0119] Based on the image crack opening and the actual crack opening, the second correction formula is determined in the following three steps:

[0120] a. Select crack data that has both image crack opening and actual crack opening corresponding to the crack opening ( Figure 7 a), calculate the difference in opening degree by formula (8)

[0121] (8)

[0122] Where: H Fiss-image is the image crack opening; H actual is the actual crack opening; H diff is the difference in opening degree;

[0123] b. Create based on the difference in opening and the image crack opening H Fiss-image ~ H diff Intersection diagram ( Figure 7 b) Establish the fitted trend line through logarithmic fitting, as shown in formula (9)

[0124] (9)

[0125] Where: H Fiss-image is the image crack opening; a 2 、 b 2 is the fitting coefficient; H diff is the difference in opening degree;

[0126] c. According to the image crack opening and the fitting trend line formula (9), determine the second correction formula (10)

[0127] (10)

[0128] Where: H corr-2 is the second calibration result; H Fiss-image is the image crack opening; H diff is the difference in opening degree;

[0129] S4.2, Second correction of crack data:

[0130] The first correction result is equivalent to the image crack opening and is substituted into formula (10) to achieve the second data correction of the crack opening, and the accuracy of the initial crack opening is corrected to be close to the accuracy of the actual crack opening.

[0131] Example 2:

[0132] The specific implementation of the present invention is described by taking the electrical imaging logging data of a certain region as an example.

[0133] S1, prepare data

[0134] Prepare fracture development section data containing 25 fractures (selected parts are shown in Table 1), including: ① Natural gamma ray (GR) logging data of fracture development section at intervals of 0.5 meters in the fracture development section GR i (i=1,2,…,n). ②Analysis software (referring to existing commercial software) crack opening, defined as the initial crack opening H Fiss-eigen ③Electrical imaging of cracks G g ④5 photos of actual core fractures G a .

[0135] S2, Data Processing

[0136] S2.1, Crack GR value processing

[0137] a. Using the half-width method to read the natural gamma ray (GR) logging data of the fracture development section GR i (i=1,2,3,…,n).

[0138] b. The natural gamma ray (GR) logging data of the fracture development section GR i (i=1,2,3,…,n) into formula (1) and calculate GR i (i=1,2,3,…,n), the calculated result is the average value of the initial crack opening H Fiss-eigen The corresponding natural gamma (GR) characteristic value of the fracture development section GReigen ( Figure 8 ).

[0139] Image data processing

[0140] S2.2, image processing to obtain image crack opening

[0141] a. Electrical imaging of cracks G g One of them contains only the crack area ( Figure 9 a) Draw the R, G, and B grayscale histograms of the area and read the grayscale value of the lowest point between the two peaks in the R grayscale histogram as the crack grayscale threshold. thresh ( thresh =20).

[0142] b. According to formula (2), the electrical imaging picture of the crack G g Perform crack segmentation to obtain electrical imaging crack segmentation image G Fiss ( Figure 9 c).

[0143] c. Crack segmentation image in electro-imaging G Fiss Four sampling points of the crack are randomly selected and the crack opening at the four sampling points is measured. H j (j=1, 2, 3, 4) Figure 9 c), the image crack opening is calculated by formula (3) H Fiss-image .

[0144] S2.3, measuring actual fracture opening using core photographs

[0145] By randomly measuring the actual core fracture photos G a The opening degree of the four pictures of the middle crack H photo-i (i=1,2,…,4) and the reference image size L photo , and determine the actual size of the reference object L actual Finally, the actual core fracture photo is calculated according to formula (4): G a Actual crack opening H actual ( Figure 10 ).

[0146] S3, first data correction

[0147] a. Based on the initial crack opening and the image crack opening, the opening ratio is calculated using formula (5).

[0148] b. Opening ratio H com and the natural gamma (GR) characteristic value of the fracture development section GR eigen Production GR eigen ~ H com Intersection diagram ( Figure 11 a), establish the fitting trend line by power function fitting, as shown in formula (11).

[0149] (11)

[0150] d. According to the initial crack opening H Fiss-eigen and fitting trend line formula (11), determine the first correction formula (formula (12)) ( Figure 11 b).

[0151] (12)

[0152] S4, second data correction

[0153] a. Select crack data that has both image crack opening and actual crack opening corresponding to each other, and calculate the opening difference using formula (8).

[0154] b. Create based on the difference in opening and the image crack opening H Fiss-image ~ H diff Intersection diagram ( Figure 12 b) Establish the fitting trend line through logarithmic fitting, as shown in formula (13).

[0155] (13)

[0156] c. Determine the second correction formula (14) based on the image crack opening and the fitting trend line formula (13).

[0157] (14)

[0158] The first calibration result H corr-1 Equivalent to the image crack opening H Fiss-image Substituting into formula (14), the second data correction of crack opening is realized. The correction results are shown in Table 1.

[0159] Table 1 Crack correction data table

[0160]

[0161] As can be seen from the above table, the present invention utilizes the secondary correction method for crack opening to achieve more accurate crack opening correction.

[0162] The above are merely preferred embodiments of the present invention. It should be noted that the above preferred embodiments should not be construed as limiting the present invention, and the scope of protection of the present invention should be determined by the scope defined in the claims. Persons skilled in the art will appreciate that improvements and modifications may be made without departing from the spirit and scope of the present invention, and such improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An electrical imaging crack opening correction method based on image crack segmentation and selection, characterized in that: The specific operations are as follows: S1, data acquisition: obtaining the initial fracture opening, natural gamma logging data of the fracture development section, electrical imaging pictures of the fracture, and actual core fracture pictures corresponding to the depth of the electrical imaging pictures of the fracture from the analysis software; S2, data processing: S2.1 obtain the natural gamma ray characteristic value of the fracture development section from the natural gamma ray logging data of the fracture development section; S2.2 The electrical imaging image of the fracture is processed to obtain the image fracture opening; S2.3 The actual fracture opening is obtained based on the actual core fracture image; S3, first correction: Perform the first crack correction based on the natural gamma ray characteristic value of the crack development section, the initial crack opening, and the image crack opening to obtain the first correction result, so that the accuracy of the initial crack opening is close to that of the image crack opening; S4, second correction: the second correction formula is obtained using the actual crack opening and the image crack opening to achieve the correction of the image crack opening to the actual crack opening. The first correction result is then equated with the image crack opening and brought into the second correction formula (10) for the second crack correction to obtain the second correction result, so that the accuracy of the first correction result is close to that of the actual crack opening. Based on the image crack opening and the actual crack opening, the second correction formula is determined in the following three steps: a. Select crack data that has both image crack opening and actual crack opening corresponding to each other, and calculate the difference in opening using formula (8) （8） Where: H Fiss-image is the image crack opening; H actual is the actual crack opening; H diff is the difference in opening degree; b. Create based on the difference in opening and the image crack opening H Fiss-image ~ H diff The intersection diagram is used to establish the fitting trend line through logarithmic fitting, as shown in formula (9): （9） Where: H Fiss-image is the image crack opening; a2 and b2 are fitting coefficients; H diff is the difference in opening degree; c. According to the image crack opening and the fitting trend line formula (9), determine the second correction formula (10) （10） Where: H corr-2 is the second calibration result; H Fiss-image is the image crack opening; H diff The difference in opening degree.

2. The electrical imaging crack opening correction method based on image crack segmentation and selection according to claim 1 is characterized in that: The specific steps of S2.1 are: processing the natural gamma logging data of the fracture development section, and using a single characteristic value to represent the natural gamma value of the fracture development section.

3. The electrical imaging crack opening correction method based on image crack segmentation and selection according to claim 1 or 2, characterized in that: The calculation of the natural gamma eigenvalue of the fracture development section includes two steps: a. Use the half-width method to read the natural gamma logging data of the fracture development section, and read the natural gamma value in 0.1m intervals; b. Calculate the natural gamma ray characteristic value of the fracture development section using formula (1) （1） Where: GR i is the natural gamma logging data of the fracture development section, where i=1,2,3,…,n; GR eigen is the natural gamma ray characteristic value of the fracture development section.

4. The electrical imaging crack opening correction method based on image crack segmentation and selection according to claim 1, characterized in that: Step S2.2 includes three steps: a. For a crack-only region in the electrical imaging image, plot the R, G, and B grayscale histograms for that region. The R grayscale histogram for that region will exhibit a multimodal distribution. The grayscale value of the lowest point between the two lowest grayscale peaks is used as the crack grayscale threshold. b. According to formula (2), the electrical imaging image of the crack is segmented to obtain the electrical imaging crack segmentation image （2） Where: src is the image gray value matrix; thresh is the crack grayscale threshold; G Fiss Segmentation images for electrical imaging cracks; c. Randomly select four sampling points of the crack in the electrical imaging crack segmentation image, measure the crack opening at the four sampling points, and calculate the image crack opening using formula (3): （3） Where: l is the diameter of the well; H j is the crack opening at the sampling point, where j = 1, 2, 3, 4; L is the width of the electro-imaging image; H Fiss-image is the image crack opening; the unit is mm.

5. The electrical imaging crack opening correction method based on image crack segmentation and selection according to claim 1, characterized in that: In S2.3, in order to ensure that there is a clear and accurate reference in the actual core fracture photograph, the fracture opening at the four sampling points in the actual core fracture photograph and the size of the reference image are measured, and the actual size of the reference is determined. Finally, the actual fracture opening in the core photograph is calculated according to formula (4): （4） Where: H photo-i is the crack photo opening, where =1, 2, 3, 4; L photo is the reference image size; L actual is the actual size of the reference object; H actual is the actual crack opening; the unit is mm.

6. The electrical imaging crack opening correction method based on image crack segmentation and selection according to claim 1, characterized in that: Step S3 is specifically as follows: S3.1, Determination of the first correction formula: The first correction formula is determined based on the natural gamma ray characteristic value of the fracture development section, the initial fracture aperture, and the image fracture aperture. It is divided into the following three steps: a. Based on the initial crack opening and the image crack opening, the opening ratio is calculated using formula (5): （5） Where: H Fiss-eigen is the initial crack opening; H Fiss-image is the image crack opening; H com is the ratio of opening degree; the unit in the formula is mm; b. Prepared based on the ratio of opening and the natural gamma ray characteristic value of the crack development section GR eigen ~ H com The intersection diagram is used to establish the fitting trend line by power function fitting, as shown in formula (6): （6） Where: a 1 、 b 1 is the fitting coefficient; c. According to the initial crack opening and the fitting trend line formula (6), determine the first correction formula (7) （7） Where: H corr-1 is the first calibration result; S3.2, First Correction of Crack Data The initial crack opening is substituted into formula (7) to realize the first data correction of the crack opening. Through the first crack data correction, the accuracy of the initial crack opening can be improved to be close to the accuracy of the image crack opening.

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