CN114527004A - Visual experiment method for dynamic expansion of internal cracks of real reduction rock core - Google Patents
Visual experiment method for dynamic expansion of internal cracks of real reduction rock core Download PDFInfo
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Abstract
A visual experiment method for dynamically expanding internal cracks of a real reduction rock core belongs to the technical field of oil and gas exploitation experiment research, and comprises the following steps: (1) acquiring three-dimensional data of an original rock core; (2) acquiring mechanical property parameters of an original core; (3) preparing a transparent photosensitive resin material with mechanical property similar to that of the original rock core; (4) using the transparent photosensitive resin material obtained in the step (3), and manufacturing a rock core model through 3D printing based on the original rock core three-dimensional data obtained in the step (1); (5) and injecting fracturing fluid into the rock core model by using a power pump, recording pressure change by using a pressure sensor, and recording the dynamic expansion process of the crack by using a high-speed camera. The invention can not only simulate different types of rock cores and reduce the internal complex structure of the rock cores to realize the real reduction of the dynamic crack expansion process in the rock cores, but also observe and record the form change of the dynamic crack expansion process in real time.
Description
Technical Field
The invention belongs to the technical field of oil and gas exploitation experimental research, and relates to a visual experimental method for real reduction of dynamic expansion of internal cracks of a rock core.
Background
Unconventional oil and gas resources are used as high-efficiency and high-quality clean energy, and the exploitation efficiency is low due to the characteristics of complex pore structure, low permeability and low porosity of a reservoir. In order to realize efficient exploitation, a fracturing technology is required to be adopted for reservoir transformation, and an artificial fracturing network is formed to obtain an oil-gas flow channel with high flow conductivity, so that the internal fracture propagation law of the reservoir becomes the focus of attention.
The Chinese invention application CN201910799587.X discloses a dynamic expansion coarse fracture network visualization device under a simulated confining pressure condition, and provides a visualization large-scale confining pressure adding and dynamic expansion fracture network proppant paving device. The device realizes that the height of the crack is variable, the height change of the crack and the height change range of the secondary crack are enlarged, the condition of a seam network with different heights of complex cracks on site is met, and the complex crack form in the rock core cannot be really reduced.
The Chinese invention application CN201910211886.7 discloses a dynamic monitoring system and a method for simulation of fracture extension of an oil and gas reservoir, which are based on real cubic rock cuttings, utilize a piston to hydraulically load a rock test piece, and dynamically monitor the extension and extension behaviors of a fracture by means of a real-time imaging function of a neutron photography system. The fracture data volume is recorded through a neutron photography system, fracture characteristics are visualized in a three-dimensional mode, fracture geometric forms of different time points are represented in a quantized mode, the evolution process of fracture formation and extension expansion is reconstructed, and real-time observation and recording of form changes in the fracture dynamic expansion process cannot be directly achieved.
The Chinese invention application CN201710448591.2 discloses a rock subcritical crack propagation visualization experiment device, a saturated fluid is arranged in a solution tank, experiment measurement of rock in the saturated fluid can be realized, in addition, the displacement of a pressure head can be changed or a load can be applied by controlling a press machine in the using process, so that the water-saturated rock crack propagation experiment under different load conditions can be completed, and the use is convenient and rapid. By adopting the waterproof camera, the crack expansion state of the rock can be recorded in the whole process, the acquisition of image data is realized, and the follow-up measurement and analysis are facilitated.
The Chinese patent application CN201610823150.1 discloses a visual experiment device and method for migration rule of proppant in a crack, which comprises the steps of taking a rock plate of a stratum to be simulated, scanning the surface of the crack of the rock plate by using a three-dimensional laser scanner, and obtaining three-dimensional data of the crack surface of the rock plate; and modeling the three-dimensional data of the rock plate crack surface by using a computer, printing a rock plate crack surface mold and a pouring box by using a 3D printing technology, and pouring two transparent resin crack plates by using transparent resin.
The Chinese patent application CN202010836804.0 discloses a multi-cluster synchronous fracturing visual simulation device, a system and a manufacturing method, natural fractures are simulated by presetting initial fractures in a positive direction or an oblique direction in a rock core experiment model, and the flow distribution and expansion forms of the multi-cluster fractures are observed, so that the complex fracture forms in the rock core cannot be reduced.
The Chinese invention application CN202011221010.X discloses a rock crack model and a device and a method for migration and laying of proppant in a rock crack, which divide a real rock into two halves; and forming two parts of the rock by using opaque silicone rubber on one half of the fracture surface and transparent plastic on the other half of the fracture surface through a casting forming method, then jointing the rough surfaces, forming cracks between the two surfaces, and observing the migration distribution of the propping agent from the position right above the transparent part.
The Chinese patent application CN201710949124.8 discloses a shale dual-medium artificial rock core and a preparation method thereof, wherein the total mass of the shale dual-medium artificial rock core is taken as a reference, a rock matrix is simulated by using a porous alumina film to provide nano pores, quartz sand provides micro pores, two porous media with different seepage capacities are provided, and the characteristics of shale dual porous media under the micro-nano scale can be simulated.
The Chinese invention application CN201811148768.8 discloses a low-permeability tight sandstone equivalent three-pore rock physical modeling method and application thereof, the method comprises the steps of separating rock core pores through three-dimensional digital rock core scanning, determining initial aspect ratios of different pore types, establishing a rock physical plate through the equivalent three-pore type aspect ratio and a self-consistent model, finally performing random simulation and calculation through the plate, outputting the porosity and the optimized shear wave speed of each pore type, and establishing an equivalent three-pore rock physical model for low-permeability tight sandstone rock on the basis of the three-dimensional digital rock core scanning and rock core rock physical test data.
The Chinese patent application CN201610144564.1 discloses a preparation method of an artificial rock core and the artificial rock core, wherein a non-ionic chain segment hydrophilic modified epoxy resin is adopted, and the hydrophilic modified epoxy resin is used for preparing the hydrophilic modified artificial rock core.
Chinese utility model patent CN202021968999.6 discloses a preparation facilities of simulation stratum core, and the fracture form of perforation department after hydraulic fracturing can be simulated to the simulation stratum core of preparation, and the fashioned environment of fracture is close to real stratum environment.
In the conventional fracture visualization research, it is difficult to truly reduce the complex structures in different types of rock cores, and simultaneously observe and record the morphological change of the dynamic fracture propagation process in real time. A visual experiment method for dynamically expanding cracks in a rock core is designed, so that complex structures in different types of rock cores can be reduced truly, and morphological changes in the dynamic expansion process of the cracks can be observed and recorded in real time, and the visual experiment method becomes an urgent necessity for research of unconventional reservoir fracturing technologies.
Disclosure of Invention
The invention aims to provide a visual experiment method for dynamically expanding internal cracks of a rock core, which can truly simulate different types of rock cores, reduce internal complex structures of the rock cores, realize the process of truly reducing the dynamic expansion of internal cracks of the rock cores, and can observe and record the form change of the dynamic expansion process of the cracks in real time. To achieve the object, the present invention has the following embodiments.
A visual experiment method for the dynamic expansion of the internal crack of a real reduction rock core is characterized by comprising the following steps:
(1) acquiring three-dimensional data of an original rock core;
(2) acquiring mechanical property parameters of an original core;
(3) preparing a transparent photosensitive resin material with mechanical properties similar to those of the original rock core;
(4) using the transparent photosensitive resin material obtained in the step (3), and manufacturing a rock core model through 3D printing based on the original rock core three-dimensional data obtained in the step (1);
(5) and injecting fracturing fluid into the rock core model by using a power pump, recording pressure change by using a pressure sensor, and recording the dynamic expansion process of the crack by using a high-speed camera.
According to the invention, through acquiring three-dimensional data and mechanical property parameters of an original rock core, a transparent photosensitive resin material with mechanical property similar to that of the original rock core is prepared, and then a rock core model is manufactured through 3D printing, so that the rock core model can truly restore complex structures in different types of rock cores; meanwhile, the pressure sensor is used for recording pressure change, the high-speed camera is used for recording the dynamic crack expansion process, and the form change of the dynamic crack expansion process can be observed and recorded in real time; therefore, the dynamic expansion process of the internal cracks of the rock core is reflected as real as possible, and a foundation is laid for researching the expansion rule of the internal cracks of the reservoir.
Further, the specific method for acquiring the three-dimensional data of the original rock core in the step (1) comprises the following steps: the method comprises the steps of obtaining an original rock core aiming at a target reservoir, obtaining three-dimensional data of the original rock core through a three-dimensional digital scanning technology, reconstructing a three-dimensional real structure, and storing the data into an STL format.
Further, the specific method for acquiring the mechanical property parameters of the original rock core in the step (2) comprises the following steps: and carrying out a uniaxial compression experiment and a triaxial stress experiment on the original core to obtain the relevant mechanical property parameters of the original core. Further, the relevant mechanical property parameters include elastic modulus and poisson's ratio.
And (3) further, the photosensitive resin material in the step (3) is prepared from a photosensitive prepolymer and an active diluent, and the mechanical property parameters of the photosensitive resin material are changed by adjusting the proportion of the photosensitive prepolymer to the active diluent so as to be close to the mechanical property parameters of the original rock core. Furthermore, the photosensitive resin material prepolymer comprises one or more of acrylic acid esterification epoxy resin, unsaturated polyester, polyurethane and polythiol/polyene light curing resin, and the reactive diluent is a low molecular weight epoxy compound containing epoxy groups. The active diluent can participate in the curing reaction of the photosensitive resin material prepolymer to become a part of a cross-linked network structure of a cured substance, the elastic modulus and Poisson ratio data of the cured substance are obtained through a uniaxial compression experiment and a triaxial stress experiment, and the mechanical property parameters of the cured substance can be changed by adjusting the proportion of the photosensitive prepolymer to the active diluent, so that the mechanical property of the cured substance is close to that of an original rock core.
Further, the specific method for manufacturing the core model by 3D printing in the step (4) comprises the following steps: uploading the three-dimensional core structure in the STL format to a 3D printer with the precision of 20-40 microns, and adopting a method of printing layer by layer and changing the printing direction in the manufacturing process. The specific process can be as follows: the three-dimensional structure is horizontally placed, a part of the core structure is manufactured, the placing angle of the core structure is changed, the model is continuously manufactured, and the core model is manufactured by changing the placing angle for multiple times. The three-dimensional experimental model manufactured in the way has multidirectional anisotropy and is closer to the real rock core condition. And after printing is finished, polishing the surface of the object to ensure that the outer surface is smooth and transparent.
Further, the fracturing fluid of step (5) is colored, so that the flowing of the fracturing fluid is convenient to observe.
Further, in the step (5), a plurality of high-speed cameras are adopted to record the dynamic crack propagation processes in different directions.
Further, the maximum acquisition speed of the high-speed camera in the step (5) is at least 9600FPS (9600 images are acquired in 1 s). Internal fracturing experimental research is carried out on a cube block with the side length of 40mm and made of transparent photosensitive resin, the material is found to crack within the range of 30-35MPa, a 960FPS (960 images are acquired in 1 s) device with the maximum acquisition speed is used for acquiring images, and the whole crack expansion process is found to be completed within 0.1s, so that a high-speed camera with the maximum acquisition speed of at least 9600FPS is selected.
Compared with the prior art, the invention has the following beneficial effects:
1) the photosensitive resin material is prepared according to the mechanical property of the original rock core, the 3D printing technology is utilized to manufacture the rock core experiment model with the complex pore structure, the corresponding experiment model can be manufactured according to different types of reservoir layers, and the experiment model can truly reduce the three-dimensional structure and the mechanical property of the reservoir layers, so that the fracturing rules of the reservoir layers with different types can be truly reflected.
2) Because the core experiment model obtained by the photosensitive resin material is transparent, the fracturing fluid with colors is used, and the morphological change of the dynamic crack propagation process can be observed and recorded in real time through a high-speed camera.
Drawings
Fig. 1 is a schematic view of a three-dimensional structural core model of example 1.
Figure 2 is an experimental model of the core of example 1.
FIG. 3 is a schematic view of the experimental apparatus of the present invention.
In the figure: 1. a power pump; 2. a pressure monitor; 3. a core experimental model; 4. a high-speed camera; 5. and (4) a beaker.
FIG. 4 is an internal fracture propagation pattern of the core of example 1.
FIG. 5 is the fracture propagation process of example 1.
Detailed Description
The technical scheme of the invention is clearly and completely described below by combining the attached drawings of the specification. It is to be understood that the described embodiments are merely exemplary of some, and not necessarily all, embodiments of the invention. All other embodiments, which can be obtained by a person skilled in the art without making creative efforts based on the embodiments of the present invention, belong to the protection scope of the present invention.
In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like are used in the orientations and positional relationships indicated in the drawings, which are based on the orientations and positional relationships indicated in the drawings, and are used for convenience in describing the present invention and for simplicity in description, but do not indicate or imply that the device or element so referred to must have a particular orientation, be constructed in a particular orientation, and be operated, and thus should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or quantity or location.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.
A visual experiment method for the dynamic expansion of cracks in a real reduction rock core comprises the following specific technical scheme:
1. a preparation stage:
(1) and aiming at the target reservoir, acquiring three-dimensional data of the original rock core by a three-dimensional digital scanning technology, reconstructing a three-dimensional real structure, and storing the data in an STL format. And carrying out uniaxial compression experiments and triaxial stress experiments on the original rock core to obtain the elastic modulus, Poisson's ratio and other relevant mechanical property parameters of the rock core.
(2) The three-dimensional experimental model is made of transparent photosensitive resin material with mechanical property similar to rock core, and in material selection, the material performance parameters are changed by adjusting the proportion of photosensitive prepolymer and active diluent in the photosensitive resin material. The photosensitive resin material prepolymer mainly comprises acrylic acid esterified epoxy resin, unsaturated polyester, polyurethane and polythiol/polyene light-cured resin, and the active diluent mainly refers to a low molecular weight epoxy compound containing epoxy groups, which can participate in the curing reaction of the epoxy resin to form a part of a cross-linked network structure of an epoxy resin cured product. And acquiring the elastic modulus and Poisson ratio data of the rock core through a uniaxial compression experiment and a triaxial stress experiment to enable the performance of the rock core to be similar to that of the target rock core.
(3) Uploading the three-dimensional rock core structure in the STL format to a 3D printer, adopting a layer-by-layer printing method in the manufacturing process, horizontally placing the three-dimensional structure, printing a part of the rock core structure, changing the placing angle of the rock core structure, continuously manufacturing the model, and changing the placing angle for multiple times to ensure that the manufactured three-dimensional experimental model has multidirectional anisotropy and is closer to the real rock core condition. And after printing is finished, polishing the surface of the object to ensure that the outer surface is smooth and transparent.
2. The assembled laboratory instrument is shown in fig. 3. Preparing the fracturing fluid with proper viscosity and color, facilitating the observation of the flowing of the fracturing fluid and placing the fracturing fluid in a beaker 5.
3. And opening the power pump 1 and the high-speed camera 4, injecting fracturing fluid into the core experiment model 3, recording pressure change by the pressure monitor 2, and recording dynamic crack extension processes in different directions by the high-speed camera 4 with the maximum acquisition speed of 9600 FPS.
The experimental method not only can truly reduce the complex structure in the rock core, but also can observe and record the morphological change of the dynamic crack propagation process in real time.
Example 1
And researching the dynamic expansion rule of the internal cracks of the rock core under the condition of vertical well development, and observing and recording the form change of the dynamic expansion process of the cracks in real time. The method comprises the following steps:
1. a preparation stage: a 40 x 40mm square core structure was designed with a vertical bore hole of 20mm length centered directly above the core and a tip structure at the bottom of the bore hole as shown in figure 1.
2. The model data is stored in STL format. Uploading the three-dimensional core structure data in the STL format to a 3D printer with the precision of 30 microns, and manufacturing a three-dimensional experimental model by adopting a layer-by-layer printing method. The printing material is a transparent photosensitive resin material with mechanical properties similar to those of the rock core. As shown in fig. 2.
3. The assembled laboratory instrument is shown in fig. 3. Preparing 2 MPa.s fracturing fluid and placing the fracturing fluid in a beaker 5.
4. The power pump 1 and the high-speed camera 4 are started, fracturing fluid is injected into the core experiment model 3, the pressure monitor 2 records pressure change,
5. the high-speed camera 4 with the maximum acquisition speed of 9600FPS records the dynamic crack propagation process in different directions. The dynamic propagation morphology of the internal fracture of the core is shown in figure 4. The dynamic propagation process of the fracture is shown in FIG. 5, and a, b and c reflect the dynamic propagation process of the fracture with the time.
In the experiment, pressure data generated by the crack can be measured by a pressure detector, and the dynamic expansion form change of the crack can be observed and recorded in real time by a high-speed camera.
Example 2
The influence of different types of rock cores on the dynamic expansion of internal cracks is researched, the mechanical characteristics of the various types of rock cores are simulated, the complex structures in the rock cores are truly reduced, and the morphological change difference of the fracturing fluid in the dynamic expansion process of the different types of rock cores is observed, recorded and compared in real time. The method comprises the following steps:
1. a preparation stage:
(1) three target reservoirs were selected: the method comprises the steps of obtaining three-dimensional data of an original rock core through a three-dimensional digital scanning technology in a sandstone reservoir, a shale reservoir and a carbonate reservoir, reconstructing a three-dimensional real structure, and storing the data in an STL format. And respectively carrying out uniaxial compression experiments and triaxial stress experiments on the three target reservoirs to obtain the elastic modulus, Poisson's ratio and other relevant mechanical property parameters of the rock core.
(2) The method is characterized in that a transparent photosensitive resin material with mechanical properties similar to rock cores is used for manufacturing a three-dimensional experimental model, and in material selection, due to the different mechanical properties of a sandstone reservoir, a shale reservoir and a carbonate reservoir, the material performance parameters are changed by adjusting the proportion of a photosensitive prepolymer and an active diluent in the photosensitive resin material. The photosensitive resin material prepolymer mainly comprises acrylic acid esterified epoxy resin, unsaturated polyester, polyurethane and polythiol/polyene light-cured resin, and the active diluent mainly refers to a low molecular weight epoxy compound containing epoxy groups, which can participate in the curing reaction of the epoxy resin to form a part of a cross-linked network structure of an epoxy resin cured product. The mechanical properties of the manufactured rock core model are greatly different due to different proportions of the photosensitive prepolymer and the active diluent in the photosensitive resin material. And acquiring the elastic modulus and Poisson ratio data of the rock core through a uniaxial compression experiment and a triaxial stress experiment to enable the performance of the rock core to be similar to that of the target rock core.
(3) Uploading the three-dimensional core structure data in the STL format to a 3D printer with the precision of 30 microns, in the manufacturing process, adopting a layer-by-layer printing method, firstly horizontally placing the three-dimensional structure, printing a part of core structure, changing the placing angle of the core structure, continuously manufacturing a model, and changing the placing angle for multiple times to ensure that the manufactured three-dimensional experimental model has multidirectional anisotropy and is closer to the real core condition. And after printing is finished, polishing the surface of the object to ensure that the outer surface is smooth and transparent.
2. The assembled laboratory instrument is shown in fig. 3.
3. Preparing 2 MPa.s of colored fracturing fluid, facilitating observation of the flowing of the fracturing fluid, and placing the fracturing fluid in a beaker 5.
4. And (3) opening the power pump 1 and the high-speed camera 4, injecting fracturing fluid into the core experiment model 3, recording pressure change by the pressure monitor 2, and recording morphological change of dynamic crack extension processes in different directions by the high-speed camera 4 (the maximum acquisition speed is 9600 FPS).
In the experiment, the pressure data generated by the cracks is measured by the pressure detector, and the dynamic expansion morphological changes of the cracks are observed and recorded in real time by the high-speed camera, so that the mechanical characteristics of various types of cores can be simulated, the complex structures in the cores can be really reduced, and the morphological change differences of the fracturing fluid in the dynamic expansion process of the cracks of the different types of cores can be observed, recorded and compared in real time.
Example 3
The influence of the fracturing fluids with different viscosities on the dynamic expansion of the cracks in the rock core is researched, and the difference of the fracturing fluids with different viscosities on the dynamic expansion process of the cracks is observed, recorded and compared in real time. The method comprises the following steps:
1. a preparation stage:
(1) and aiming at a target reservoir, acquiring three-dimensional data of an original rock core by a three-dimensional digital scanning technology, reconstructing a three-dimensional real structure, and storing the data in an STL format. And carrying out uniaxial compression experiments and triaxial stress experiments on the target core to obtain the elastic modulus, Poisson's ratio and other relevant mechanical property parameters of the core.
(2) The three-dimensional experimental model is made of transparent photosensitive resin material with mechanical property similar to rock core, and in material selection, the material performance parameters are changed by adjusting the proportion of photosensitive prepolymer and active diluent in the photosensitive resin material. The photosensitive resin material prepolymer mainly comprises acrylic acid esterified epoxy resin, unsaturated polyester, polyurethane and polythiol/polyene light-cured resin, and the active diluent mainly refers to a low molecular weight epoxy compound containing epoxy groups, which can participate in the curing reaction of the epoxy resin to form a part of a cross-linked network structure of an epoxy resin cured product. And acquiring the elastic modulus and Poisson ratio data of the rock core through a uniaxial compression experiment and a triaxial stress experiment to enable the performance of the rock core to be similar to that of the target rock core.
(3) Uploading the three-dimensional core structure data in the STL format to a 3D printer with the precision of 30 microns, in the manufacturing process, adopting a layer-by-layer printing method, firstly horizontally placing the three-dimensional structure, printing a part of core structure, changing the placing angle of the core structure, continuously manufacturing a model, and changing the placing angle for multiple times to ensure that the manufactured three-dimensional experimental model has multidirectional anisotropy and is closer to the real core condition. And after printing is finished, manually polishing the surface of the object to ensure that the outer surface is smooth and transparent.
2. The assembled laboratory instrument is shown in fig. 3.
3. Preparing the fracturing fluid with colors of 2 MPa.s, 10 MPa.s, 20 MPa.s, 30 MPa.s, 50 MPa.s, 70 MPa.s, 90 MPa.s, 110 MPa.s and 130 MPa.s, facilitating the observation of the flowing of the fracturing fluid, and placing the fracturing fluid in a beaker 5.
4. And (3) opening the power pump 1 and the high-speed camera 4, injecting fracturing fluid into the core experiment model 3, recording pressure change by the pressure monitor 2, and recording morphological change of dynamic crack extension processes in different directions by the high-speed camera 4 (the maximum acquisition speed is 9600 FPS).
According to the experiment, the pressure data when the cracks are generated is measured through the pressure detector, the dynamic expansion morphological changes of the cracks are observed and recorded in real time through the high-speed camera, the complex structure in the rock core can be truly reduced, and the morphological change differences of fracturing fluids with different viscosities in the dynamic expansion process of the cracks can be observed, recorded and compared in real time.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made in the above embodiments by those of ordinary skill in the art without departing from the principle and spirit of the present invention. The scope of the invention is defined by the claims and their equivalents.
Claims (10)
1. A visual experiment method for dynamic propagation of cracks in a real reduction rock core is characterized by comprising the following steps:
(1) acquiring three-dimensional data of an original rock core;
(2) acquiring mechanical property parameters of an original core;
(3) preparing a transparent photosensitive resin material with mechanical properties similar to those of the original rock core;
(4) using the transparent photosensitive resin material obtained in the step (3) to make a rock core model through 3D printing based on the original rock core three-dimensional data obtained in the step (1);
(5) and injecting fracturing fluid into the rock core model by using a power pump, recording pressure change by using a pressure sensor, and recording the dynamic expansion process of the crack by using a high-speed camera.
2. The visualization experiment method as claimed in claim 1, wherein the step (1) of obtaining the three-dimensional data of the original core comprises the following specific steps: the method comprises the steps of obtaining an original rock core aiming at a target reservoir, obtaining three-dimensional data of the original rock core through a three-dimensional digital scanning technology, reconstructing a three-dimensional real structure, and storing the data into an STL format.
3. A visualization experiment method as claimed in claim 1, wherein the specific method for acquiring the mechanical property parameters of the original rock core in the step (2) is as follows: and carrying out a uniaxial compression experiment and a triaxial stress experiment on the original core to obtain the relevant mechanical property parameters of the original core.
4. A visualization experiment method as claimed in claim 3, wherein the relevant mechanical property parameters include elastic modulus and poisson's ratio.
5. A visualization experiment method as claimed in claim 1, wherein the photosensitive resin material in step (3) is prepared from photosensitive prepolymer and reactive diluent, and the mechanical property parameters of the photosensitive resin material are changed to be close to those of the original rock core by adjusting the ratio of the photosensitive prepolymer to the reactive diluent.
6. The visual experimental method of claim 5, wherein the photosensitive resin material prepolymer comprises one or more of acrylated epoxy resin, unsaturated polyester, polyurethane and polythiol/polyene photocurable resin, and the reactive diluent is a low molecular weight epoxy compound containing epoxy groups.
7. The visualization experiment method as claimed in claim 1, wherein the specific method for making the core model by 3D printing in the step (4) is as follows: uploading the three-dimensional core structure in the STL format to a 3D printer with the precision of 20-40 microns, and adopting a method of printing layer by layer and changing the printing direction in the manufacturing process.
8. A visual experimental method according to claim 1, characterized in that the fracturing fluid of step (5) is colored.
9. The visual experiment method of claim 1, wherein step (5) uses several high-speed cameras to record the dynamic crack propagation process in different directions.
10. A visual experiment method according to claim 1, wherein the maximum acquisition speed of the high-speed camera in the step (5) is at least 9600 FPS.
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