Method for evaluating improvement effect of pressure bearing capacity of stratum

Abstract

The invention provides a method for evaluating the improvement effect of the pressure bearing capacity of a stratum, and belongs to the technical field of oil and gas drilling, and the method comprises the following steps: S1, obtaining a fissure area reference value S < base > of a first original simulation core; s2, acquiring a fracture area test value S < test > of the second original simulated rock core after the plugging experiment; and S3, according to the fissure area reference value S < base > and the fissure area test value S < measurement >, calculating to obtain a fissure change rate ROC. According to the method, a real stratum is replaced by the self-made simulated rock core, the improvement effect of the plugging drilling fluid on the loading capacity of the simulated rock core is evaluated by comparing the fracture area change conditions of the internal cross section of the original simulated rock core before and after the plugging experiment, the method is simple, efficient and easy to operate, and the evaluation result is visual and reliable.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas drilling, and in particular relates to a method for evaluating the effect of improving the pressure bearing capacity of a formation. Background Art

[0002] Improving the pressure bearing capacity of the formation is an important part of expanding the narrow safety density window drilling fluid technology. Usually, the pressure bearing capacity of the formation is increased by injecting plugging drilling fluid or plugging slurry into the wellbore, which increases the upper limit of the safe use of the drilling fluid density and ensures safe drilling under narrow (or negative) safety density window conditions. This is an important requirement for oil and gas exploration and development drilling.

[0003] Normally, the formula of plugging drilling fluid or plugging slurry needs to be developed in the laboratory and then put into use at the drilling construction site. During the laboratory development stage, it is necessary to evaluate the effect of plugging drilling fluid or plugging slurry on improving the formation pressure bearing capacity. However, most of the current evaluations are on-site and lack effective indoor evaluation methods.

[0004] Chinese invention patent CN103485771A discloses a method for testing the pressure bearing capacity of formations before cementing, and the steps are as follows: Step 1: After drilling, directly lower the drill pipe to the casing shoe, design the wellhead pressurization value according to the maximum annulus dynamic equivalent density during cementing, gradually pressurize the wellhead, find the pump pressure inflection point or the wellhead pressure reaches the design value, stop the inspection, record the final pressure data, and then calculate the pressure bearing capacity of the formation at the casing shoe. If the formation pressure bearing capacity meets the requirements, proceed to the second step, the pressure bearing capacity inspection of the weak formation of the open hole formation. This method can accurately obtain the pressure bearing capacity of the weak formation, overcome the shortcomings of the traditional static test method of the pressure bearing capacity of the formation, which is easy to leak the formation at the upper casing shoe, and also avoid the blindness of the traditional dynamic test method of the pressure bearing capacity of the formation to determine the density of the weighted drilling fluid and the circulation displacement, and has strong on-site operability. However, this method is a test and evaluation method at the cementing construction site, not an indoor evaluation method.

[0005] Chinese invention patent CN109915128A discloses a dynamic test method for formation pressure bearing capacity and a cementing method. The present invention first collects the wellhead pressure when the performance of the drilling fluid outlet and inlet is consistent; then calculates the circulating dynamic friction generated by the drilling fluid in each well section of the annulus according to the collected wellhead pressure, as well as the annulus and casing size parameters; finally, calculates the dynamic fluid column pressure acting on the layer according to the annulus wellbore size and the calculated circulating dynamic friction, and obtains the formation pressure bearing capacity. The present invention utilizes the circulating dynamic friction generated by the drilling fluid in the circulation channel composed of the casing and the annulus, and the static fluid column pressure of the drilling fluid acts on the formation together, and changes the size of the circulating dynamic friction by adjusting the circulation displacement, so as to test the pressure bearing capacity of different layers. The method obtains the formation pressure bearing capacity by collecting field data such as wellhead pressure and circulating dynamic friction, which is also a field test evaluation method.

[0006] Chinese invention patent CN110826142A discloses a method for predicting the bearing capacity of fractured formation plugging, including the following steps: S1, obtaining rock mechanics parameters, construction parameters and parameters of the plugging layer; S2, obtaining the bridging distance of the plugging layer; S3, finally calculating the expansion pressure of the plugged fracture according to the prediction model of the bearing capacity of fractured formation plugging. This method predicts the bearing capacity of the formation based on the rock mechanics parameters, construction parameters and parameters of the plugging layer collected on site, and also relies on field data. Summary of the invention

[0007] In view of the problems existing in the above-mentioned prior art, the present invention provides a method for evaluating the effect of improving the pressure bearing capacity of the formation. The technical problem to be solved by the present invention is to solve the problem that the prior art lacks an indoor evaluation method for the effect of improving the pressure bearing capacity of the formation.

[0008] In order to solve the above technical problems, the present invention provides a method for evaluating the effect of improving the pressure bearing capacity of a formation, comprising the following steps:

[0009] Step S1: Obtain the fracture area reference value S of the first original simulated core 基 ;

[0010] Step S2: Obtain the fracture area test value S of the second original simulated core after the plugging experiment 测 ;

[0011] Step S3: Based on the crack area reference value S 基 The crack area test value S 测 , the crack change rate ROC is calculated.

[0012] Furthermore, in step S1, the following steps are included:

[0013] Step S11: acquiring a first original simulated core image;

[0014] Step S12: Process and analyze the first original simulated core image to obtain a fracture area reference value S of the first original simulated core. 基 .

[0015] Furthermore, in step S11, the following steps are included:

[0016] Step S111: preparing a first original simulated core;

[0017] Step S112: cross-cutting the first original simulated core obtained in step S111;

[0018] Step S113: Acquire a cross-section image to obtain a first original simulated core image.

[0019] Furthermore, in step S111, a base slurry is prepared with water, bentonite and calcium carbonate as raw materials, the base slurry is poured into the kettle of the filter loss meter and pressurized and heated, the kettle is opened after natural cooling, the mud cake at the bottom of the kettle is taken out, the mud cake is rinsed and dried, and the first original simulated core and the second original simulated core are obtained.

[0020] Furthermore, in step S12, the following steps are included:

[0021] Step S121: obtaining a grayscale image of a first original simulated core;

[0022] Step S122: converting the grayscale image of the first original simulated core into a binary image;

[0023] Step S123: Scan the binary image and extract feature values;

[0024] Step S124: Calculate the fracture area reference value S of the first original simulated core 基 .

[0025] Furthermore, in step S121, the first original simulated core image is grayed using a weighted average method to obtain a grayscale image.

[0026] Furthermore, in step S122, the grayscale image is binarized, a threshold is set as C0, and each pixel value of the grayscale image is scanned. Those less than C0 are marked as C1, and those greater than or equal to C0 are marked as C2.

[0027] Furthermore, in step S123, the binary image is scanned row by row and column by column to obtain the number of points X1 of the C1 pixel value and the number of points Y1 of the C2 pixel value respectively, and the area of ​​the binary image is recorded as A1.

[0028] Furthermore, in step S124, the crack area reference value S is calculated by the following formula: 基 :

[0029] S 基 =A1×(X1 / (X1+Y1)).

[0030] Furthermore, in step S2, the following steps are included:

[0031] Step S21: using the second original simulated core to perform a plugging experiment;

[0032] Step S22: collecting the second original simulated core image after the plugging experiment;

[0033] Step S23: Process and analyze the second original simulated core image after the plugging experiment to obtain the fracture area test value S of the second original simulated core after the plugging experiment. 测 .

[0034] Furthermore, in step S21, the plugging experiment includes the following steps: placing the second original simulated core at the bottom of the kettle of the filter loss instrument, pouring plugging slurry into the kettle, pressurizing and heating, opening the kettle after natural cooling, pouring out the plugging slurry, taking out the mud cake at the bottom of the kettle, rinsing it with clean water and drying it, to obtain the second original simulated core after the plugging experiment.

[0035] Furthermore, in step S22, the following steps are included:

[0036] Step S221: cross-cutting the second original simulated core after the plugging experiment;

[0037] Step S222: collecting a cross-sectional image to obtain a second original simulated core image after the plugging experiment.

[0038] Furthermore, in step S23, the following steps are included:

[0039] Step S231: obtaining a grayscale image of the second original simulated core after the plugging experiment;

[0040] Step S232: converting the grayscale image of the second original simulated core after the plugging experiment into a binary image;

[0041] Step S233: Scan the binary image and extract feature values;

[0042] Step S234: Calculate the second original simulated core fracture area reference value S after the plugging experiment 测 .

[0043] Furthermore, in step S231, the second original simulated core image after the plugging experiment is grayed out using a weighted average method to obtain a gray image.

[0044] Furthermore, in step S232, the grayscale image is binarized, the threshold is set as D0, and each pixel value of the grayscale image is scanned. Those less than D0 are marked as X2, and those greater than or equal to D0 are marked as Y2.

[0045] Further, in step S234, the second original simulated core fracture area reference value S after the plugging experiment is calculated using the following formula: 测 :

[0046] S 测 =A2×(X2 / (X2+Y2)).

[0047] Furthermore, in step S3, the calculation formula of the crack change rate ROC is as follows:

[0048] ROC=(S 基 -S 测 ) / S 基 .

[0049] The present invention discloses a method for evaluating the effect of improving the pressure bearing capacity of a formation. A self-made simulated rock core is used to replace the real rock formation. By comparing the changes in the crack areas of the cross-section inside the original simulated rock core before and after the plugging experiment, the effect of the plugging drilling fluid on improving the pressure bearing capacity of the simulated rock core is evaluated. The method is simple, efficient, easy to operate, and the evaluation result is intuitive and reliable.

[0050] The present invention provides a method for evaluating the effect of improving the pressure bearing capacity of a formation. The method can evaluate the effect of improving the pressure bearing capacity of a plugging drilling fluid or a plugging slurry in a laboratory, which is simple and efficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 The present invention is a flow chart of a method for evaluating the effect of improving the pressure bearing capacity of a formation. DETAILED DESCRIPTION

[0052] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0053] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0054] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0055] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0056] In order to better understand the purpose, structure and function of the present invention, a method for evaluating the effect of improving the bearing capacity of a formation according to the present invention is further described in detail below in conjunction with the accompanying drawings.

[0057] Embodiment 1:

[0058] like Figure 1 As shown, the present invention provides a method for evaluating the effect of improving the pressure bearing capacity of a formation, comprising the following steps:

[0059] Step S1: Obtain the fracture area reference value S of the first original simulated core 基 ;

[0060] Step S2: Obtain the fracture area test value S of the second original simulated core after the plugging experiment 测 ;

[0061] Step S3: Based on the crack area reference value S 基 The crack area test value S 测 , the fracture change rate ROC is calculated, which is the effect of improving the pressure bearing capacity of the simulated core.

[0062] Embodiment 2:

[0063] like Figure 1 As shown, the present invention provides a method for evaluating the effect of improving the pressure bearing capacity of a formation, comprising the following steps:

[0064] Step S1: Obtain the fracture area reference value S of the first original simulated core 基;

[0065] Step S2: Obtain the fracture area test value S of the second original simulated core after the plugging experiment 测 ;

[0066] Step S3: Based on the crack area reference value S 基 The crack area test value S 测 , the calculated fracture change rate ROC is the effect of improving the pressure bearing capacity of the simulated core.

[0067] The difference between this embodiment and the first embodiment is that:

[0068] In step S3, the calculation formula of the crack change rate ROC is as follows:

[0069] ROC=(S 基 -S 测 ) / S 基 .

[0070] Embodiment 3:

[0071] like Figure 1 As shown, the present invention provides a method for evaluating the effect of improving the pressure bearing capacity of a formation, comprising the following steps:

[0072] Step S1: Obtain the fracture area reference value S of the first original simulated core 基 ;

[0073] Step S2: Obtain the fracture area test value S of the second original simulated core after the plugging experiment 测 ;

[0074] Step S3: Based on the crack area reference value S 基 The crack area test value S 测 , the fracture change rate ROC is calculated, which is the effect of improving the pressure bearing capacity of the simulated core.

[0075] The difference between this embodiment and the first embodiment is that:

[0076] Wherein, in step S1, specifically including:

[0077] Step S11: acquiring a first original simulated core image;

[0078] Step S12: Process and analyze the first original simulated core image to obtain a fracture area reference value S of the first original simulated core. 基 .

[0079] Wherein, in step S11, it specifically includes:

[0080] Step S111: preparing a first original simulated core;

[0081] Step S112: cross-cut the first original simulated core obtained in step S111 at half the height;

[0082] Step S113: using a CCD camera to collect a cross-section image, which is the first original simulated core image.

[0083] In step S111, specifically:

[0084] The base slurry is prepared with water, bentonite and calcium carbonate as raw materials, poured into the kettle of the high-temperature and high-pressure filter loss instrument and heated under pressure, opened after the kettle is naturally cooled, poured out the excess base slurry, took out the mud cake at the bottom of the kettle, rinsed it with clean water and dried it to obtain the original simulated core, which includes the first original simulated core and the second original simulated core.

[0085] Wherein, in step S12, specifically including:

[0086] Step S121: obtaining a grayscale image;

[0087] The first original simulated core image is grayed out by using a weighted average method to obtain a gray image;

[0088] Step S122: converting the grayscale image into a binary image;

[0089] Binarize the grayscale image, set the threshold value as C0, scan each pixel value of the grayscale image, mark it as C1 if it is less than C0, and mark it as C2 if it is greater than or equal to C0;

[0090] Step S123: extracting features;

[0091] Scan the binary image row by row and column by column to obtain the number of points X1 of the C1 pixel value and the number of points Y1 of the C2 pixel value respectively. The area of ​​the binary image is recorded as A1.

[0092] Step S124: Obtaining the crack area reference value S 基 ;

[0093] By formula S 基 =A1×(X1 / (X1+Y1)), and obtain the fracture area reference value S of the first original simulated core 基 .

[0094] Embodiment 3:

[0095] like Figure 1 As shown, the present invention provides a method for evaluating the effect of improving the pressure bearing capacity of a formation, comprising the following steps:

[0096] Step S1: Obtain the fracture area reference value S of the first original simulated core 基 ;

[0097] Step S2: Obtain the fracture area test value S of the second original simulated core after the plugging experiment 测 ;

[0098] Step S3: Based on the crack area reference value S 基 The crack area test value S 测 , the fracture change rate ROC is calculated, which is the effect of improving the pressure bearing capacity of the simulated core.

[0099] The present embodiment is different from the above embodiments in that:

[0100] Wherein, in step S2, specifically including:

[0101] Step S21: using the second original simulated core to perform a plugging experiment;

[0102] Step S22: collecting simulated core images after the plugging experiment;

[0103] Step S23: Process and analyze the second original simulated core image after the plugging experiment to obtain the fracture area test value S of the second simulated core after the plugging experiment. 测 .

[0104] Among them, in step S21, the blocking experiment is specifically as follows:

[0105] Place the original simulated core at the bottom of the kettle of the high-temperature and high-pressure filter loss instrument, pour the plugging slurry into the kettle, heat it under pressure, open it after the kettle cools down naturally, pour out the excess plugging slurry, take out the mud cake at the bottom of the kettle, rinse it with clean water and dry it, and you will get the simulated core after the plugging experiment.

[0106] Wherein, in step S22, specifically including:

[0107] Step S221: cross-cutting the second original simulated core after the plugging experiment at half the height;

[0108] Step S222: using a CCD camera to collect a cross-sectional image, which is the second original simulated core image after the plugging experiment.

[0109] Wherein, in step S23, specifically including:

[0110] Step S231: obtaining a grayscale image;

[0111] The second original simulated core image after the plugging experiment is grayed out using the weighted average method to obtain a grayscale image;

[0112] Step S232: converting the grayscale image into a binary image;

[0113] Binarize the grayscale image, set the threshold value as D0, scan each pixel value of the grayscale image, mark it as D1 if it is less than D0, and mark it as D2 if it is greater than or equal to D0;

[0114] Step S233: extracting features;

[0115] Scan the binary image row by row and column by column to obtain the number of points X2 of the pixel value of D1 and the number of points Y2 of the pixel value of D2 respectively. The area of ​​the binary image is recorded as A2.

[0116] Step S234: obtaining a crack area reference value;

[0117] By formula S 测 =A2×(X2 / (X2+Y2)), and obtain the fracture area test value Stest of the second original simulated core after the plugging experiment.

[0118] Embodiment 4:

[0119] A fourth embodiment of a method for evaluating the effect of improving the pressure bearing capacity of a formation provided by the present invention is used to conduct actual measurement of the above method for evaluating the effect of improving the pressure bearing capacity of a formation, and is specifically as follows:

[0120] Step S1: Obtain the fracture area reference value S of the first original simulated core 基 is 12, the specific steps are as follows:

[0121] Step S11: acquiring a first original simulated core image;

[0122] Step S111: preparing a first original simulated core;

[0123] In this step, two identical simulated cores are prepared respectively, that is, the same method is operated twice. The specific method is: 100 parts by weight of water, 10 parts by weight of bentonite and 25 parts by weight of calcium carbonate are used as raw materials to prepare base slurry, the base slurry is poured into the kettle of the high-temperature and high-pressure filter loss instrument and pressurized and heated for 30 minutes at a pressure of 3.5 MPa and a temperature of 80°C. After the end, the kettle is opened after natural cooling, the excess base slurry is poured out, the mud cake at the bottom of the kettle is taken out, rinsed with clean water and then dried at a drying temperature of 50°C to obtain two original simulated cores, which are respectively recorded as the first original simulated core and the second original simulated core.

[0124] Step S112: cross-cut the first original simulated core obtained in step S111 at half the height;

[0125] Step S113: using a CCD camera to collect a cross-section image, which is the first original simulated core image.

[0126] Step S12: Process and analyze the first original simulated core image to obtain a fracture area reference value S of the original simulated core.基 .

[0127] Step S121: obtaining a grayscale image;

[0128] The first original simulated core image is grayed out by using a weighted average method to obtain a gray image;

[0129] Step S122: converting the grayscale image into a binary image;

[0130] Binarize the grayscale image, set the threshold to 127, scan each pixel value of the grayscale image, mark it as 0 if it is less than 127, and mark it as 255 if it is greater than or equal to 127;

[0131] Step S123: extracting features;

[0132] Scan the binary image row by row and column by column to obtain the number of points X1 with 0 pixel value, the number of points Y1 with 255 pixel value and the area A1 of the binary image respectively;

[0133] Step S124: obtaining a crack area reference value;

[0134] The fracture area benchmark value S of the first original simulated core is obtained by the formula S = A1 × (X1 / (X1+Y1)). 基 =12.

[0135] In step S2, the fracture area test value S of the second simulated core after the plugging experiment is obtained. 测 The specific steps are as follows:

[0136] Step S21: performing a plugging experiment using the second original simulated core obtained in step S111;

[0137] The second original simulated core prepared in step S111 is placed at the bottom of the kettle of the high-temperature and high-pressure filter loss instrument, and plugging slurry is poured into the kettle (the formula of the plugging slurry is 100 parts by weight of water, 3 parts by weight of bentonite, 1 part by weight of low-viscosity polyanionic cellulose, 5 parts by weight of 400-mesh calcium carbonate powder, 10 parts by weight of 1250-mesh calcium carbonate powder, and 6 parts by weight of nano paraffin; Note: the plugging slurry can be selected according to the formula determined by the specific experiment, and this formula is only used as an example for the experiment here), and pressurized and heated at a temperature of 140°C and a pressure of 3.5 MPa. The experiment time is 30 minutes. After the end, the kettle is opened after natural cooling, and the excess plugging slurry is poured out. The mud cake at the bottom of the kettle is taken out, rinsed with clean water, and then dried to obtain the simulated core after the plugging experiment.

[0138] Step S22: collecting the second original simulated core image after the plugging experiment;

[0139] Step S221: cross-cutting the second original simulated core after the plugging experiment at half the height;

[0140] Step S222: using a CCD camera to collect a cross-sectional image, which is the second original simulated core image after the plugging experiment;

[0141] Step S23: Process and analyze the second simulated core image after the plugging experiment to obtain the fracture area test value S of the second simulated core after the plugging experiment. 测 ;

[0142] Step S231: obtaining a grayscale image;

[0143] The second simulated core image after the plugging experiment is grayed out using a weighted average method to obtain a grayscale image;

[0144] Step S232: converting the grayscale image into a binary image;

[0145] Binarize the grayscale image, set the threshold to 127, scan each pixel value of the grayscale image, mark it as 0 if it is less than 127, and mark it as 255 if it is greater than or equal to 127;

[0146] Step S233: extracting features;

[0147] Scan the binary image row by row and column by column to obtain the number of points X2 with 0 pixel value, the number of points Y2 with 255 pixel value and the area A2 of the binary image respectively;

[0148] Step S234: obtaining a crack area reference value;

[0149] S 测 =A2×(X2 / (X2+Y2))

[0150] Using this formula, the fracture area test value S of the simulated core after the plugging experiment is obtained: 测 is 4.

[0151] Step S3: According to the formula ROC = (S 基 -S 测 ) / S 基 , and the crack change rate ROC = 67%, which is the effect of improving the pressure bearing capacity of the simulated core.

[0152] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A method for evaluating the effect of improving the bearing capacity of a formation, characterized in that: The following steps are involved: Step S1: Obtain the fracture area reference value S of the first original simulated core 基 ; Step S2: Obtain the fracture area test value S of the second original simulated core after the plugging experiment 测 ; Step S3: Based on the crack area reference value S 基 The crack area test value S 测 , the crack change rate ROC is calculated.

2. The method for evaluating the effect of improving the bearing capacity of a formation according to claim 1, characterized in that: In step S1, the following steps are included: Step S11: acquiring a first original simulated core image; Step S12: Process and analyze the first original simulated core image to obtain a fracture area reference value S of the first original simulated core. 基 .

3. The method for evaluating the effect of improving the bearing capacity of a formation according to claim 2, characterized in that: In step S11, the following steps are included: Step S111: preparing a first original simulated core; Step S112: cross-cutting the first original simulated core obtained in step S111; Step S113: Acquire a cross-section image to obtain a first original simulated core image.

4. The method for evaluating the effect of improving the bearing capacity of a formation according to claim 3, characterized in that: In step S111, a base slurry is prepared with water, bentonite and calcium carbonate as raw materials, and the base slurry is poured into the kettle of the filter loss meter and pressurized and heated. After the kettle is naturally cooled, it is opened, the mud cake at the bottom of the kettle is taken out, and the mud cake is rinsed and dried to obtain the first original simulated core and the second original simulated core.

5. The method for evaluating the effect of improving the bearing capacity of a formation according to claim 2, characterized in that: In step S12, the following steps are included: Step S121: obtaining a grayscale image of a first original simulated core; Step S122: converting the grayscale image of the first original simulated core into a binary image; Step S123: Scan the binary image and extract feature values; Step S124: Calculate the fracture area reference value S of the first original simulated core 基 .

6. The method for evaluating the effect of improving the bearing capacity of a formation according to claim 5, characterized in that: In step S121, the first original simulated core image is grayed using a weighted average method to obtain a grayscale image.

7. The method for evaluating the effect of improving the bearing capacity of a formation according to claim 5, characterized in that: In step S122, the grayscale image is binarized, the threshold is set as C0, and each pixel value of the grayscale image is scanned. Those less than C0 are marked as C1, and those greater than or equal to C0 are marked as C2.

8. The method for evaluating the effect of improving the bearing capacity of a formation according to claim 7, characterized in that: In step S123, the binary image is scanned row by row and column by column to obtain the number of points X1 of the C1 pixel value and the number of points Y1 of the C2 pixel value respectively, and the area of ​​the binary image is recorded as A1.

9. The method for evaluating the effect of improving the bearing capacity of a formation according to claim 8, characterized in that: In step S124, the crack area reference value S is calculated by the following formula: 基 : S 基 =A1×(X1 / (X1+Y1))。 10. The method for evaluating the effect of improving the bearing capacity of a formation according to claim 1, characterized in that: In step S2, the following steps are included: Step S21: using the second original simulated core to perform a plugging experiment; Step S22: collecting the second original simulated core image after the plugging experiment; Step S23: Process and analyze the second original simulated core image after the plugging experiment to obtain the fracture area test value S of the second original simulated core after the plugging experiment. 测 .

11. The method for evaluating the effect of improving the bearing capacity of a formation according to claim 10, characterized in that: In step S21, the plugging experiment includes the following steps: placing the second original simulated core at the bottom of the kettle of the filter loss instrument, pouring plugging slurry into the kettle, pressurizing and heating, opening the kettle after natural cooling, pouring out the plugging slurry, taking out the mud cake at the bottom of the kettle, washing it with clean water and drying it, to obtain the second original simulated core after the plugging experiment.

12. The method for evaluating the effect of improving the bearing capacity of a formation according to claim 10, characterized in that: In step S22, the following steps are included: Step S221: cross-cutting the second original simulated core after the plugging experiment; Step S222: collecting a cross-sectional image to obtain a second original simulated core image after the plugging experiment.

13. The method for evaluating the effect of improving the bearing capacity of a formation according to claim 10, characterized in that: In step S23, the following steps are included: Step S231: obtaining a grayscale image of the second original simulated core after the plugging experiment; Step S232: converting the grayscale image of the second original simulated core after the plugging experiment into a binary image; Step S233: Scan the binary image and extract feature values; Step S234: Calculate the second original simulated core fracture area reference value S after the plugging experiment 测 .

14. The method for evaluating the effect of improving the bearing capacity of a formation according to claim 13, characterized in that: In step S231, the second original simulated core image after the plugging experiment is grayed out using a weighted average method to obtain a gray image.

15. The method for evaluating the effect of improving the bearing capacity of a formation according to claim 13, characterized in that: In step S232, the grayscale image is binarized, the threshold is set as D0, and each pixel value of the grayscale image is scanned. If it is less than D0, it is marked as X2, and if it is greater than or equal to D0, it is marked as Y2.

16. The method for evaluating the effect of improving the bearing capacity of a formation according to claim 15, characterized in that: In step S234, the second original simulated core fracture area reference value S after the plugging experiment is calculated using the following formula: 测 : S 测 =A2×(X2 / (X2+Y2))。 17. The method for evaluating the effect of improving the pressure bearing capacity of a formation according to claim 1, characterized in that: In step S3, the calculation formula of the crack change rate ROC is as follows: ROC=(S 基 -S 测 ) / S 基 。

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