Core processing method for simulating formation fracture network for reservoir damage and protection evaluation

Abstract

The present application belongs to the technical field of oil and gas production, and relates to a core processing method for simulating a formation fracture network for reservoir damage and protection evaluation, comprising the following steps: preparing a plurality of core columns reflecting the formation composition of the evaluation oil and gas reservoir; taking the prepared core columns, forming forces in the directions of two horizontal principal stresses and overburden pressure on the core columns according to a preset loading mode and interval time, so that the same fracture-microfracture fracture network as the formation rock of the oil and gas reservoir is formed in the core; obtaining a stereogram of the fracture network through digital core scanning, and calculating the fracture degree and high-density mineral data of the fracture body, and establishing the fracture distribution of the core after fracturing, until the fracture degree and high-density mineral data of the core column are consistent with the fracture degree and high-density mineral data of the formation core. The present application can produce a formation rock core consistent with the formation seepage channel, and the established core better simulates the formation condition, and the evaluation result is more reliable.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of oil and gas production, and particularly relates to a core processing method for simulating a formation fracture network for reservoir damage and protection evaluation. BACKGROUND

[0002] In drilling and completion, the damage to the oil and gas reservoir is mainly caused by the column pressure of drilling fluid, cementing fluid, completion fluid and perforating fluid, which is far higher than the pore pressure of the oil and gas reservoir. When the working fluid is injected into the oil and gas reservoir, the oil and gas channel is narrowed or blocked, and the permeability of the oil and gas reservoir is reduced. The result of the reservoir damage is to reduce the production capacity and yield, to affect the estimation of the reserve capacity, to affect the development plan, to increase the work load and cost of oil testing, acidification, fracturing and well repair, and to affect the ultimate recovery rate and damage the oil and gas resources. Therefore, in the drilling and completion operation, the damage to the reservoir should be reduced as much as possible, and the oil and gas reservoir should be protected as much as possible.

[0003] In the development of a certain layer, in order to protect the oil and gas reservoir from the damage in the drilling and completion, the damage evaluation should be performed on the fluid introduced in each process of the drilling and completion, and the experimental evaluation should be performed on whether the protection measures used in each stage are effective, so as to ensure that the damage of the drilling and completion to the oil and gas reservoir is minimized and the protection measures used are optimal. Therefore, it is very important to accurately test the damage of each process, fluid system and reservoir protection formula of the drilling and completion to the oil and gas reservoir.

[0004] For general reservoirs (such as average, medium porosity, medium permeability reservoirs), the prior art is to determine the core sensitivity (including velocity sensitivity, water sensitivity, salt sensitivity, alkali sensitivity, acid sensitivity, etc.) and the permeability recovery value after the reservoir damage by working fluid to obtain the damage degree of the drilling and completion process to the reservoir and the effect of the protection measures. The core step of the core sensitivity evaluation experiment is: drilling the rock core of the reservoir, displacing the rock core with fluids (fresh water, formation brine, acid, alkali, etc.) simulating different drilling and completion processes, allowing the fluids to react with the reservoir rock, and defining the sensitivity degree of the reservoir to the external fluids by the permeability change before and after the reaction of the fluids with the rock. The core of the drilling and completion working fluid damage and protection evaluation experiment is to directly react the working fluid with the formation rock core taken from the reservoir, to determine the core permeability values before and after the reaction, and to determine the damage degree of the reservoir and the protection effect of the reservoir protection formula by the numerical change. According to the above experimental evaluation, one of the core factors in the damage and protection evaluation of the reservoir is the formation rock core taken from the reservoir, which requires the same composition as the reservoir formation, the same physical and chemical reactions when reacting with different drilling and completion fluids, and the same pore and permeability conditions as the reservoir formation, i.e. the same seepage channel in oil and gas development and production after the reaction. For general reservoirs, the seepage channel is mainly the pore, so the formation core taken from the formation has the same composition and the same porosity as the formation, so this method can simulate the formation conditions and the evaluation results are reliable.

[0005] In recent years, with the rapid development of the world economy, the global demand for oil and natural gas has also increased rapidly, and with the decreasing of conventional oil and gas resources, unconventional oil and gas resources have become the main battlefield of exploration and development, and their efficient development and utilization are of great significance to maintain economic stable growth and ensure national energy security. In the development process of unconventional oil and gas resources, the development of tight sandstone gas reservoirs with developed micro-fractures occupies an important position.

[0006] In the development of tight sandstone gas reservoirs with developed fractures and micro-fractures, one of the cores of the sensitivity evaluation and damage evaluation of the working fluid of the reservoir is to process and manufacture rock cores consistent with the composition and seepage channel of the oil and gas reservoir. For tight sandstone with developed fractures and micro-fractures, the rock core taken from the formation has the same composition as the formation, but there is no way to simulate the formation fractures and micro-fractures, because the formation fractures and micro-fractures are developed, and it is impossible to form a complete core when drilling the core, so it is impossible to form a rock core with the same porosity and permeability structure as the oil and gas reservoir formation.

[0007] To solve the problem, the prior art is to take the formation core of the oil and gas reservoir layer without the formation fracture and micro-fracture, to ensure that the taken core is the same as the formation composition, and then to fracture the formation fracture by using the Brazilian fracture experiment or to establish a fracture on the formation core by using the cutting and sectioning method to simulate the formation pore and permeability condition. The Brazilian fracture experiment, the sectioning experiment and the cutting experiment can only establish a linear fracture in the core, and the fracture shape is single, and in most cases, there is only one fracture. Since the fracture opening degree is not easy to control, the seepage channel of the processed formation core is larger than the actual seepage channel at the well bottom, and therefore it is not easy to simulate the formation condition. SUMMARY

[0008] The purpose of the present application is to provide a core processing method for simulating the formation fracture network for reservoir damage and protection evaluation, and to solve the problem that the core with the same fracture and micro-fracture as the formation cannot be taken out.

[0009] The present application is realized by the following technical solutions:

[0010] A core processing method for simulating the formation fracture network for reservoir damage and protection evaluation, comprising the following steps:

[0011] S1, obtaining the numerical three-dimensional graph of the simulated reservoir formation core fracture by using the digital core scanning method, and calculating the fracture degree and high-density mineral content of the simulated reservoir formation;

[0012] S2, preparing a plurality of core columns reflecting the composition of the evaluated oil and gas reservoir formation;

[0013] S3, taking the core column prepared in S2, forming two horizontal principal stresses and overburden pressure forces in three directions on the core column according to the preset loading mode and interval time, so that the same fracture-micro-fracture network as the oil and gas reservoir formation rock is formed in the core;

[0014] S4, establishing the fracture distribution of the core after fracturing by using the digital core scanning method until the fracture degree and high-density mineral content of the core column are consistent with the fracture degree and high-density mineral content of the simulated reservoir formation core, and then the core processing is completed.

[0015] Further, S2 specifically comprises the following steps:

[0016] S21, drilling a plurality of circular columnar cores at the rock without fracture or micro-fracture, and cutting two sections;

[0017] If the formation to be evaluated has less or no core, and the circular columnar core cannot be drilled, then a circular columnar core is drilled on the outcrop core of the same formation layer by taking the outcrop core of the same formation layer;

[0018] S22, drying the circular columnar core in a drying box to obtain a qualified core column.

[0019] Further, the diameter of the circular columnar core is 24.5 mm, and the length is 40-60 mm.

[0020] Further, in S22, if the mass change before and after drying is less than 1%, the core column is qualified.

[0021] Further, S3 specifically comprises the following steps:

[0022] S31, taking the core column prepared in S2, wrapping several layers of transparent tape, and reserving a length of the tape for controlling the tension degree when wrapping the tape;

[0023] S32, taking the core column wrapped with transparent tape in S31, placing it in a stress clamp, and shaking the handle to clamp the core;

[0024] S33, after shaking the stress clamp handle, stopping for 3-5 minutes;

[0025] S34, observing the core column surface and both end surfaces in the stress clamp, and stopping loading when cracks visible to the naked eye appear on the surface or the end surfaces;

[0026] S35, removing the clamping force of the stress clamp, taking out the core column, rotating the core column by 45°, and repeating the steps S21-S24 to ensure uniform distribution of cracks in the core.

[0027] Further, in S31, 2-5 layers of transparent tape are wrapped.

[0028] Further, in S3, when the formation fracture permeability is 0.1-10 mD, the number of layers of transparent tape wrapped is 5, the reserved length of the tape is controlled to be within 2 mm, the pressure angle of the stress clamp handle is 45°, and the intermittent time after single pressure is 5 min;

[0029] when the formation fracture permeability is 10-100 mD, the number of layers of transparent tape wrapped is 4, the reserved length of the tape is controlled to be 4-8 mm, the pressure angle of the stress clamp handle is 60°-90°, and the intermittent time after single pressure is 4-5 min;

[0030] when the formation fracture permeability is 100-1000 mD, the number of layers of transparent tape wrapped is 3, the reserved length of the tape is controlled to be 10-14 mm, the pressure angle of the stress clamp handle is 90°, and the intermittent time after single pressure is 3-4 min.

[0031] Further, in S33, the shaking angle is 45-90°.

[0032] Further, S4 specifically comprises the following process:

[0033] Take the core column in which fracture processing is completed in S3, establish the fracture distribution of the core after fracture creation, and again use the digital core scanning method to obtain the reconstructed stereogram of the fracture network of the fracture creation core, and calculate the fracture porosity and high-density mineral content of the fracture network;

[0034] If the fracture porosity and high-density mineral content of a certain fracture network are less than the requirements of the simulated reservoir formation, the core column is placed into the stress clamp for continuous loading until the requirements are met.

[0035] Further, the digital core scanning method is specifically:

[0036] After the rock is penetrated by X-rays, attenuation occurs, and according to different degrees of attenuation, two-dimensional X-ray imaging is performed; then the sample is rotated for 360° scanning, a series of two-dimensional projection images are obtained, filtering and contrast enhancement are performed, the surrounding structure of the rock is reconstructed, and a three-dimensional model of the rock sample is obtained.

[0037] Compared with the prior art, the present application has the following beneficial technical effects:

[0038] The core processing method for simulating a fracture network of a reservoir formation for reservoir damage and protection evaluation disclosed in the present application forms a fracture-microfracture network in the core according to a preset loading mode and interval time, which is the same as the fracture-microfracture network of the rock in the oil and gas reservoir formation, and a core with the same pore and permeability as the rock in the oil and gas reservoir formation can be formed, and the specific reason is that the fracture path of the rock in the oil and gas reservoir formation is affected by geological stress, according to research results, the geological stress can be divided into two horizontal principal stresses and the force in the direction of overburden pressure, in the present application, the pressure on the two end faces of the stress clamp is used to simulate the horizontal principal stress in the geological process, and the tension provided by the wrapping tape is used to simulate the overburden pressure. Therefore, under this action mode, the fracture-microfracture generated is the same as that generated in the geological process.

[0039] Further, after the rock is penetrated by X-rays, attenuation occurs, and according to different degrees of attenuation, two-dimensional X-ray imaging is performed; then the sample is rotated for 360° scanning, a series of two-dimensional projection images are obtained, filtering and contrast enhancement are performed, the surrounding structure of the rock is reconstructed, and a three-dimensional model of the rock sample is obtained, different gray scales are used to represent the fracture pore space, and the fracture porosity and high-density mineral content are calculated. The fracture porosity and high-density mineral content of the core of a certain fracture network are retrieved, and are consistent with the simulated reservoir formation, if the fracture porosity and high-density mineral content of the digital core scanning are less than the requirements of the formation, the core column is placed into the stress clamp for continuous loading until the requirements are met.

[0040] The application can produce the formation rock core consistent with the formation seepage channel, and can be used for fracture-microfracture formation drilling completion fluid damage evaluation and protection countermeasure research. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 A three-dimensional fracture network image of the formation core in the example is obtained by digital scanning reconstruction;

[0042] Figure 2 A three-dimensional fracture network image of the core after coring and fracturing in the example is obtained by digital scanning reconstruction. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical scheme and advantages of the application more clear and obvious, the following further detailed description is made in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the application, and are not used to limit the application, that is, the described examples are only a part of the examples of the application, but not all examples.

[0044] The components described and shown in the drawings and examples of the application can be arranged and designed in various different configurations, therefore, the detailed description of the examples of the application provided in the following drawings is not intended to limit the scope of the claimed application, but only represents a selected embodiment of the application. Based on the drawings and examples of the application, all other examples obtained by those skilled in the art without creative labor are within the protection scope of the application.

[0045] It should be noted that the terms "comprise", "include" or any other variant thereof are intended to cover non-exclusive inclusion, so that the process, element, method, article or equipment including a series of elements includes not only those elements, but also other elements not explicitly listed or inherent to the process, element, method, article or equipment.

[0046] The application discloses a core processing method of simulated formation fracture network for reservoir damage and protection evaluation, which can process experimental cores consistent with the composition and porosity and permeability of the formation rock of the oil and gas reservoir, and can be used for reservoir damage and protection evaluation experiments in the development of fractured and microfractured oil and gas reservoirs.

[0047] The application provides the experimental core processing method of the oil and gas reservoir formation rock consistent with the composition and porosity, which comprises the following steps:

[0048] S1, obtaining a numerical three-dimensional image of the simulated reservoir formation core fracture by using a digital core scanning method, and calculating the fracture degree and high-density mineral content of the simulated reservoir formation.

[0049] S2, several small core columns reflecting the formation composition of the evaluation reservoir formation are prepared;

[0050] S3, the small core columns prepared in S2 are taken, a stress clamp is applied, a force in three directions of two horizontal principal stresses and overburden pressure is formed on the core columns according to a given loading mode and interval time, so that the same fracture-microfracture network as the reservoir formation rock is formed in the core columns;

[0051] S4, a digital core scanning method is used to establish the fracture distribution of the core columns after the fractures are formed, until the fracture porosity and high-density mineral content of the core columns are consistent with the simulated reservoir formation core fracture porosity and high-density mineral content, and then the core processing is completed.

[0052] Further, the step S2 specifically comprises:

[0053] S21, a small round columnar core with a diameter of 24.5 mm and a length of 40-60 mm is drilled at a rock without fractures or microfractures, and the two sections are flattened.

[0054] S22, the small round columnar core is naturally dried in a drying box, and the mass change is less than 1% after two times of weighing, which is qualified.

[0055] In this way, the use of small round columnar cores can simulate the conditions of the formation rock, and the small round columnar cores can be taken from the formation to be evaluated, which ensures that the displacement medium is the same as the formation. If the formation to be evaluated has less or no core, the small round columnar core cannot be drilled, and the small round columnar core can be drilled on the outcrop core of the same formation layer. Since the formation is the same, the properties of the formation rock are basically the same. In addition, the length of the small round columnar core must be greater than 40 mm, otherwise it is not enough to simulate the formation medium.

[0056] Further, the step S3 specifically comprises:

[0057] S31, the small core column prepared in S2 is taken, and 2-5 layers of transparent tape are wound, and a certain length is reserved for controlling the tension degree when winding the tape;

[0058] S32, the small core column after winding the transparent tape in S31 is taken, and the core is clamped by shaking the handle in the stress clamp.

[0059] S33, the handle of the stress clamp is slowly shaken, and the shaking angle is preferably 45-90°, and after shaking the handle, stop for 3-5 minutes.

[0060] S34, the small core column in the stress clamp is observed, and when the column surface or the end surface has visible cracks, the loading is stopped.

[0061] S35, remove the stress clamp holding force, remove the small core column, rotate the core column by 45°, and repeat the steps S31-S34.

[0062] In this way, the reason for winding the small core column with transparent tape is that the core of the dense formation has greater brittleness, and is easy to collapse during loading, causing core damage. Winding the transparent tape can prevent the collapse of part of the rock during core pressurization, and by adjusting the tightness of the transparent tape, a crack is formed in the core to increase the volume for control. The stress clamp is used to load the small core column, and the small core column is slowly loaded and clamped, and at the same time, the time interval is certain, which is used for the cracks inside the core to generate and extend to form a crack network; the reason for adjusting the core by 45° is to ensure that the cracks in the core are evenly distributed.

[0063] The reason for using the above method to form a crack-micro crack consistent with the pore and permeability of the oil and gas reservoir rock is that the crack travel of the oil and gas reservoir rock is affected by the geological stress. According to the research results, the geological stress can be divided into two horizontal principal stresses and three forces in the direction of overburden pressure. In this experiment, the pressure of the stress clamp on both ends is used to simulate the horizontal principal stress in the geological process, and the tension provided by the winding tape is used to simulate the overburden pressure. Therefore, under this action mode, the cracks-micro cracks generated are the same as those generated in the geological process.

[0064] Further, the step S4 specifically comprises:

[0065] Take the small core column with cracks processed in S3, and establish the crack distribution of the core after the crack is formed according to the digital core scanning method;

[0066] Retrieve the fracture degree and high-density mineral content of the core of a crack network, which is consistent with the fracture degree and high-density mineral content of the formation core. If the fracture degree and high-density mineral content are less than those of the formation core, the small core column can be placed in the stress clamp for continuous loading until the requirements are met.

[0067] Digital core scanning method: after x-ray transillumination of the rock, two-dimensional X-ray imaging is performed according to different degrees of attenuation; then the sample is rotated for 360° scanning to obtain a series of two-dimensional projection images, which are filtered and contrast-enhanced to reconstruct the surrounding structure of the rock and obtain a three-dimensional model of the rock sample. Different gray scales are used to represent crack pore space, and the fracture degree and high-density mineral content are calculated.

[0068] In this way, the fracture degree and high-density mineral content of the formation are compared with the actual crack forming results to determine whether they can remain consistent within the error range.

[0069] The application also provides a method for controlling the fracture network parameters consistent with the evaluated formation rock core, and specifically includes the transparent adhesive tape winding layer number, the adhesive tape reserved length, the single stress clamp handle rotation angle, the single pressurization interval time and the like. Specifically, the operation can be performed according to the following table.

[0070]

[0071]

[0072] In this way, the fracture network is formed under the quantified and controllable condition parameters, and the actual operation is easy. The above parameters are derived based on the basic knowledge of fracture mechanics, and are formed after being modified based on the actual operation. Different formation core loading may be slightly different.

[0073] The method disclosed by the application has been applied to the oil and gas reservoir damage evaluation and protection technology research of the Bozi and DaBei blocks of the Tarim Oilfield Company of PetroChina. The formation of the area is dense, and the fractures-microfractures are developed. The rock core consistent with the formation needs to be manufactured in all experimental evaluations.

[0074] As shown in Figure 1 , the fracture network three-dimensional image is obtained by digitally scanning the simulated formation core, the fracture porosity is calculated as 1.12%, and the high-density mineral content is calculated as 0.52%. After the method provided by the application is used, the core consistent with the formation is processed, as shown in Figure 2 , the fracture network three-dimensional image is obtained by digitally scanning the cored and fractured core, the fracture porosity is calculated as 1.41%, and the high-density mineral content is calculated as 0.71%. The fracture porosity and the high-density mineral content of the core column are basically consistent with the fracture porosity and the high-density mineral content of the simulated reservoir formation core, and then the core processing is completed.

[0075] Then, the damage evaluation experiment is carried out using the manufactured core, the experimental results are reasonable and reliable, and good effects are obtained. The experimental process is as follows:

[0076] Experiment name: drilling fluid damage rate experiment on double medium of Bozi DaBei block

[0077] (1) Experimental purpose

[0078] Evaluate the permeability recovery value of the drilling fluid and master its reservoir protection performance.

[0079] (2) Experimental instruments

[0080] Experimental instruments: high-speed stirrer, beaker, 100mL measuring cylinder, 1000mL measuring cylinder, low-speed stirrer, electronic scale, glass rod, porcelain cylinder, timer, core displacement experiment device.

[0081] Formation core: Bozi, Daobei reservoir core

[0082] Experimental evaluation of damaging fluid

[0083] 1#: water-based drilling fluid for Bozi and Daobei reservoir section, density 1.84 g / cm3.

[0084] 2#: high-density oil-based drilling fluid for Bozi and Daobei reservoir section, density 1.81 g / cm3

[0085] (3) Experimental procedure

[0086] ① Use stress calipers to control the pressure of the core taken from the reservoir to create a fracture network, with a controlled permeability of 40-100 mD.

[0087] ② Gas measurement of core permeability;

[0088] ③ Preparation of simulated formation water and saturated core

[0089] Simulated formation water formula: 2.0% potassium chloride + 5.5% sodium chloride + 0.45% magnesium chloride + 0.55% calcium chloride, prepared into simulated formation water with a concentration of 8.5%, the core is placed in the brine for 24h, the mass of the core before and after saturation is measured, and the pore volume is calculated.

[0090] ④ Measurement of core permeability K1 before damage

[0091] Inject 5 PV of simulated formation water into the core at a rate of 2.52 mL / min, maintain the flow rate and pressure difference stable, and record the pressure difference and flow rate, calculate the permeability K1 before damage.

[0092] ⑤ Damage process

[0093] The drilling fluid is loaded into a high-pressure container, and a pressure pump is used to pressurize, so that the drilling fluid solution is injected into the core at a rate of 0.50 mL / min. When the drilling fluid solution begins to flow out, record the time and cumulative filtration volume of the drilling fluid solution. During the measurement process, the measurement time is 36 min, and the temperature is allowed to fluctuate by ±5℃. After the injection is completed, close the valves at both ends of the clamps, and allow the foaming agent solution to displace in the core under a confining pressure of 5.0 MPa and a constant pressure of 3.0 MPa for 3h.

[0094] ⑥ Measurement of core permeability K2 after damage

[0095] According to the method in ④, the permeability K2 of the core after being damaged by the drilling fluid solution is measured, and the reservoir damage rate and permeability recovery value of the drilling fluid are calculated.

[0096] (4) Experimental data

[0097] The cores of Bozi and Da Beizi formations were taken in the experiment. Because the formation is dense, the pressure is too high during liquid displacement, so the cores were broken by pressure clamp to increase the permeability, which was used to determine the permeability recovery value in the drilling fluid damage experiment. The core information used in the experiment is shown in Table 1, and the experimental results are shown in Table 2.

[0098] Table 1 Core information table for drilling fluid damage experiment

[0099]

[0100] Table 2 Drilling fluid core damage experiment data

[0101]

[0102] (5) Experimental conclusion

[0103] The permeability damage of water-based drilling fluid to the squeezed cores of Bozi and Da Beizi formations is 60% to 70%; the permeability damage rate of oil-based drilling fluid is 40% to 50%. In comparison, the base fluid damage of oil-based drilling fluid is small. The damage degree of Bozi and Da Beizi is basically the same, which is related to the core permeability. The greater the core permeability, the smaller the damage.

[0104] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, but not to limit it. Although the present application has been described in detail with reference to the above examples, those skilled in the art should understand that the specific embodiments of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the present application. Any modification or equivalent replacement without departing from the spirit and scope of the present application should be covered in the protection scope of the claims of the present application.

Claims

1. A core processing method for a simulated formation fracture network for reservoir damage and protection evaluation, characterized by, It comprises the following steps: S1, obtaining the numerical stereogram of the simulated reservoir formation core cracks by using the digital core scanning method, and calculating the fissure degree and high-density mineral content of the simulated reservoir formation; S2, preparing a plurality of core columns reflecting the formation composition of the evaluated oil and gas reservoir formation; S3, taking the core column prepared in S2, forming two horizontal principal stresses and overburden pressure forces in three directions on the core column according to a preset loading mode and interval time, so that the same fracture-microfracture network as the oil and gas reservoir formation rock is formed in the core column; S4, establishing the fracture distribution of the fractured core by using the digital core scanning method until the fissure degree and high-density mineral content of the core column are consistent with the fissure degree and high-density mineral content of the simulated reservoir formation, and then the core processing is completed; S3 specifically comprises the following steps: S31, taking the core column prepared in S2, winding a plurality of layers of transparent adhesive tape, and reserving a length of the adhesive tape for controlling the tension degree when winding the adhesive tape; S32, taking the core column wound with the transparent adhesive tape in S31, placing the core column into the stress clamp, and clamping the core column by shaking the handle; S33, stopping for 3-5 minutes after shaking the handle of the stress clamp; S34, observing the column surface and the two end surfaces of the core column in the stress clamp, and stopping loading when the cracks visible to the naked eye appear on the column surface or the end surfaces; S35, removing the clamping force of the stress clamp, taking out the core column, rotating the core column by 45°, and repeating the steps S31-S34 to ensure that the fracture distribution in the core column is uniform; S4 specifically comprises the following process: taking the core column with completed fracture processing in S3, establishing the fracture distribution of the fractured core, and again obtaining the reconstructed stereogram of the fracture network of the fractured core by using the digital core scanning method, and calculating the fissure degree and high-density mineral content of the fracture network; if the fissure degree and high-density mineral content of a certain fracture network are less than the requirements of the simulated reservoir formation, then the core column is placed into the stress clamp for continuous loading until the requirements are met.

2. The core processing method for a simulated formation fracture network for reservoir damage and protection evaluation according to claim 1, characterized by, S2 specifically comprises the following steps: S21, drilling a plurality of circular columnar cores at the rock without cracks or micro-cracks, and cutting off two sections; if the cores of the formation to be evaluated are less or no cores are taken, the circular columnar cores are drilled on the outcrop cores of the same formation; S22, naturally drying the circular columnar cores in a drying box to obtain qualified core columns.

3. The core processing method for a simulated formation fracture network for reservoir damage and protection evaluation according to claim 2, characterized in that, The diameter of the circular columnar core is 24.5 mm, and the length is 40-60 mm.

4. The core processing method for a simulated formation fracture network for reservoir damage and protection evaluation according to claim 2, characterized by, In S22, if the mass change before and after drying is less than 1%, then the core column is qualified.

5. The core processing method for a simulated formation fracture network for reservoir damage and protection evaluation according to claim 1, characterized in that, In S31, the transparent adhesive tape is wound for 2-5 layers.

6. The core processing method for a simulated formation fracture network for reservoir damage and protection evaluation according to claim 5, characterized in that, In S3, when the formation fracture permeability is 0.1-10 mD, the number of layers of the transparent adhesive tape is 5, the reserved length of the adhesive tape is controlled to be within 2 mm, the pressure angle of the stress clamp handle is 45°, and the interval time after single pressure is 5 min; when the formation fracture permeability is 10-100 mD, the number of layers of the transparent adhesive tape is 4, the reserved length of the adhesive tape is controlled to be 4-8 mm, the pressure angle of the stress clamp handle is 60°-90°, and the interval time after single pressure is 4-5 min; When the formation fracture permeability is 100-1000 mD, the transparent adhesive tape winding layer number is 3, the adhesive tape reserved length is controlled in 10-14 mm, the stress clamp handle pressurizing angle is 90°, and the single pressurizing after intermittent time is 3-4 min.

7. The core processing method for a simulated formation fracture network for reservoir damage and protection evaluation according to claim 1, characterized in that, In S33, the shaking angle is 45-90°.

8. The core processing method for a simulated formation fracture network for reservoir damage and protection evaluation according to claim 1, characterized in that, The digital core scanning method specifically is: After the x ray transillumination rock, the attenuation occurs, according to different attenuation degree, carries out two-dimensional X-ray imaging, then rotates the sample and carries out 360 ° scanning, obtains a series of two-dimensional projection images, carries out filtering and contrast enhancement, reconstructs the rock surrounding structure, obtains the rock sample three-dimensional model.

Images