An experimental device and experimental method for simulating a fracture network

Abstract

The present invention relates to the field of experimental equipment for oil and gas field development, specifically an experimental device for simulating a fracturing network, including a liquid supply and sand mixing system, a pumping device and a visual flat plate model, wherein a liquid inlet pipe and a liquid outlet pipe are arranged on the visual flat plate model; a main crack, a secondary crack and a tertiary crack are arranged in the visual flat plate model, wherein the width of the main crack gradually decreases from one end connected to the liquid inlet pipe to one end connected to the liquid outlet pipe; the width of the secondary crack gradually decreases from one end connected to the main crack to one end connected to the liquid outlet pipe; the width of the tertiary crack gradually decreases from one end connected to the secondary crack to one end connected to the liquid outlet pipe. The present invention combines the actual formation crack expansion situation, and the widths of the main crack, the secondary crack and the tertiary crack gradually decrease along the extension direction of the crack length, thereby more realistically reflecting the laying situation of the proppant in the complex crack network, optimizing the reasonable fracturing construction parameters, and guiding the oil field to carry out fracturing production.

Description

Technical Field

[0001] The invention relates to the field of experimental equipment for oil and gas field development, in particular to an experimental device and an experimental method for simulating a fracture network. Background Art

[0002] At present, the development of medium and high permeability reservoirs has entered the middle and late stages of development. The water content increases and the recovery rate decreases. In order to further increase crude oil production, the development of low permeability, ultra-low permeability and tight oil and gas reservoirs is very important. For the development of low permeability reservoirs, hydraulic fracturing technology is the main technical means. At present, hydraulic fracturing of low permeability, ultra-low permeability and tight oil and gas reservoirs mainly includes vertical well fracturing and horizontal well fracturing. After a new fracture is formed in a vertical well or horizontal well, the proppant is laid in the fracture. The degree of proppant laying in the fracture determines the height and length of the fracture, and further determines the fracture control radius and affected area. Therefore, it is very important to study the laying rules of proppant in complex fracture networks. By studying the laying rules of proppant in fractures under different construction parameters, the fracturing construction parameters are optimized to guide the on-site fracturing construction and improve the recovery rate of the reservoir. At present, the research on the laying rules of proppants in cracks is mainly carried out through visual flat plate models. For the existing visual flat plate model, reference can be made to CN104533404B, which discloses a visual experimental device for simulating the migration of proppants in a complex fracture network, including a liquid supply and sand mixing system, a pumping system, a pipeline transportation system, a visual fracture network system (visual flat plate model), a circulating fluid treatment system, a numerical control acquisition system and a control system, wherein the visual fracture network system includes vertical main fractures and connecting fractures, the vertical main fractures are two parallel vertical fractures, the vertical main fractures are two parallel vertical fractures, the connecting fracture is arranged between the two vertical main fractures and is respectively connected to the two vertical main fractures, the vertical main fracture includes two transparent plates arranged parallel to each other, the two sides are sealed, and the two ends are arranged as simulated inlets and simulated outlets, and the connecting fracture includes two transparent plates arranged parallel to each other, the two sides are sealed, and the two ends are arranged as simulated inlets and simulated outlets.

[0003] In actual working conditions, the upper crack will generate secondary cracks, and the width of the secondary crack is smaller than that of the upper crack. As the length of the crack extends, the crack width decreases. The current visualization plate model can only study the case of constant crack width, and does not consider the gradual change of crack width. Summary of the invention

[0004] The purpose of the present invention is to solve the deficiencies of the above-mentioned prior art and provide an experimental device for simulating a fracturing network. Combined with the actual formation fracture expansion, the widths of the main fractures, secondary fractures and tertiary fractures gradually decrease along the extension direction of the fracture length, thereby more realistically reflecting the laying of proppants in a complex fracture network, optimizing reasonable fracturing construction parameters, and guiding oil fields to carry out fracturing production.

[0005] The technical problem to be solved by the present invention is achieved by adopting the following technical scheme: an experimental device for simulating a fracturing network, comprising a liquid supply and sand mixing system, a pumping device and a visual flat plate model, wherein a liquid inlet pipe and a liquid outlet pipe are arranged on the visual flat plate model, the outlet of the liquid supply and sand mixing system is connected to the liquid inlet pipe through the pumping device, and the liquid outlet pipe is connected to the inlet of the liquid supply and sand mixing system; a main crack, a secondary crack and a tertiary crack are arranged in the visual flat plate model, the two ends of the main crack are respectively connected to the liquid inlet pipe and the liquid outlet pipe, and the width of the main crack gradually decreases from one end connected to the liquid inlet pipe to one end connected to the liquid outlet pipe; one end of the secondary crack is connected to the main crack, and the other end of the secondary crack is connected to the liquid outlet pipe, and the width of the secondary crack gradually decreases from one end connected to the main crack to one end connected to the liquid outlet pipe; one end of the tertiary crack is connected to the secondary crack, and the width of the tertiary crack gradually decreases from one end connected to the secondary crack to one end connected to the liquid outlet pipe.

[0006] The technical solution of the present invention also includes: the main cracks, the secondary cracks and the tertiary cracks are each provided with two and are symmetrically arranged. The technical solution is used to simulate a double-wing hydraulic fracture network.

[0007] The technical solution of the present invention also includes: one main crack is provided, and two secondary cracks are provided and are spaced apart along the length direction of the main crack. This technical solution is used to simulate a single-wing hydraulic fracture network.

[0008] The technical solution of the present invention also includes: the liquid inlet pipe is provided with simulated perforations. The technical solution is used to simulate the vertical well injection fracture network.

[0009] The technical solution of the present invention also includes: a horizontal well connected to a liquid inlet pipe. The technical solution is used to simulate the injection of a horizontal well into a fracture network.

[0010] The technical solution of the present invention also includes: the liquid supply and sand mixing system includes a clean water tank, a liquid preparation tank, a sand mixing tank and a pump, the outlet of the liquid preparation tank is connected to the inlet of the sand mixing tank through the pump, and the outlet of the clean water tank and the outlet of the sand mixing tank are both connected to the inlet of the pumping device. In this technical solution, the clean water tank stores clean water for cleaning the visualized flat plate model after the experiment; the liquid preparation tank is used to prepare fracturing fluid, and additives such as cross-linking agents are added to the liquid preparation tank. After the fracturing fluid is prepared in the liquid preparation tank, it is pumped to the sand mixing tank, and the sand is evenly mixed in the sand mixing tank. Then, the sand mixing liquid is pumped into the flat plate model through the pumping device.

[0011] The technical solution of the present invention also comprises: the pumping device is a screw pump.

[0012] The technical solution of the present invention also includes: the visualization flat plate model includes multiple model units, the model unit includes a frame, a pressure plate, a transparent plate and a sealing strip, the transparent plate is provided with two pieces and embedded in the frame, the sealing strip is provided between the upper and lower edges of the two transparent plates, the pressure plate is connected to the frame by bolts and the transparent plate is fixed in the frame, and the model units are connected by multi-way joints; the inner side of the transparent plate is provided with a cone surface, and the main crack, secondary crack and tertiary crack are formed between the two transparent plates. By adopting this technical solution, the transparent plate can be replaced according to the seam network form required by the experiment, and the visualization flat plate model can be assembled quickly and conveniently.

[0013] The present invention also provides an experimental method for simulating a fracturing network, comprising the following steps:

[0014] a. According to the experimental requirements, determine the injection method and fracture network form to be simulated, then assemble the experimental device simulating the fracture network, check the air tightness of each part, prepare the experimental materials required for the experiment, and install sensors and cameras;

[0015] b. Prepare the fracturing fluid through the fluid supply and sand mixing system, and put the proppant into the fluid supply and sand mixing system;

[0016] c. Turn on the pumping device and pump the fracturing fluid into the visualized flat plate model, so that the fracturing fluid is filled in the visualized flat plate model;

[0017] d. Configure proppant in the fluid supply and sand mixing system according to the sand ratio required by the experiment;

[0018] e. Pump the proppant into the visualized flat plate model through a pumping device. The proppant settles in the primary fractures, secondary fractures and tertiary fractures through the visualized flat plate model to form a sand bank. The fracturing fluid returns to the fluid supply and sand mixing system through the liquid outlet pipe;

[0019] f. Turn on the camera to record the dynamic changes of the sand bank;

[0020] g. After the proppant laying experiment is completed, the liquid supply and sand mixing system pumps clean water into the visual flat plate model through a pumping device to clean the visual flat plate model.

[0021] Compared with the prior art, the beneficial effects of the experimental device for simulating a fracturing network of the present invention are as follows: (1) in combination with the actual formation fracture expansion, the widths of the main fractures, secondary fractures and tertiary fractures gradually decrease along the extension direction of the fracture length, thereby more realistically reflecting the laying of the proppant in the complex fracture network, optimizing reasonable fracturing construction parameters, and guiding the fracturing production in the oil field; (2) it can simulate various working conditions such as the horizontal well double-wing fracturing network, the vertical well single-wing fracturing network, and the vertical well double-wing fracturing network, and has a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a stereoscopic image of the visualized flat plate model in the first embodiment.

[0023] Figure 2 Schematic diagram of the structure of the experimental device for simulating the fracturing network in Example 1.

[0024] Figure 3 for Figure 2 Sectional view of item AA.

[0025] Figure 4 for Figure 2 A partial enlarged view of part B in the middle.

[0026] Figure 5 The sand bank morphology diagram of the main fracture formed by proppants of different mesh sizes in Example 1.

[0027] Figure 6 Schematic diagram of the structure of the experimental device for simulating the fracturing network in Example 2.

[0028] Figure 7 Schematic diagram of the structure of the experimental device for simulating the fracturing network in Example 3.

[0029] Figure 8 This is a diagram of the sand bank morphology of the secondary fracture formed by different flow rates in the fracture in Example 3.

[0030] Fig. 9 The sand bank morphology diagram of the main crack formed in Example 1 and the comparative example.

[0031] In the figure: 1. liquid inlet pipe, 2. liquid outlet pipe, 3. main fracture, 4. secondary fracture, 5. tertiary fracture, 6. simulated perforation, 7. horizontal well, 8. clean water tank, 9. liquid distribution tank, 10. sand mixing tank, 11. pump, 12. screw pump, 13. frame, 14. pressure plate, 15. transparent plate, 16. sealing strip, 17. multi-way joint, 18. automatic sand adding device. DETAILED DESCRIPTION

[0032] In order to clearly illustrate the technical features of the present invention, the specific implementation methods of the present invention are further described below with reference to the accompanying drawings.

[0033] like Figure 1-Figure 4 As shown, an experimental device for simulating a fracturing network includes a fluid supply and sand mixing system, a pumping device and a visual flat plate model.

[0034] like Figure 2As shown, the liquid supply and sand mixing system includes a clean water tank 8, a liquid preparation tank 9, a sand mixing tank 10, a pump 11 and an automatic sand adding device 18. The outlet of the liquid preparation tank 9 is connected to the inlet of the sand mixing tank 10 through the pump 11. The outlet of the clean water tank 8 and the outlet of the sand mixing tank 10 are both connected to the inlet of the pumping device. The pumping device of this embodiment is a screw pump 12. The automatic sand adding device 18 is connected to the inlet of the sand mixing tank 10 and can automatically add sand to the sand mixing tank 10.

[0035] A liquid inlet pipe 1 and a liquid outlet pipe 2 are provided on the visualized flat plate model. The outlet of the liquid supply and sand mixing system is connected to the liquid inlet pipe 1 through a screw pump 12, and the liquid outlet pipe 2 is connected to the inlet of the liquid supply and sand mixing system.

[0036] The visual slab model includes several model units, such as Figure 3 and Figure 4 As shown, the model unit includes a frame 13, a pressure plate 14, a transparent plate 15 and a sealing strip 16. The transparent plate 15 is provided with two pieces and embedded in the frame 13. The sealing strip 16 is provided between the upper and lower edges of the two transparent plates 15. The pressure plate 14 is connected to the frame 13 by bolts and fixes the transparent plate 15 in the frame 13. The model units are connected by a multi-way joint 17.

[0037] A conical surface is provided on the inner side of the transparent plate 15, and a main crack 3, a secondary crack 4 and a tertiary crack 5 are formed between the two transparent plates 15. One main crack 3 is provided, and two secondary cracks 4 are provided and are arranged at intervals along the length direction of the main crack 3. A liquid inlet pipe 1 is provided at one end of the main crack 3, and the liquid inlet pipe 1 simulates a vertical wellbore, and adopts the controllable perforation position physical simulation wellbore disclosed in CN109057787A, and is provided with simulated perforations 6. The visualized flat plate model of this embodiment is used to simulate a single-wing hydraulic fracture network of a vertical well.

[0038] The two ends of the main crack 3 are connected to the liquid inlet pipe 1 and the liquid outlet pipe 2 respectively. Figure 2 and Figure 4 As shown, the width of the main crack 3 gradually decreases from 8 mm to 6 mm along the end connected to the liquid inlet pipe 1 to the end connected to the liquid outlet pipe 2. One end of the secondary crack 4 is connected to the main crack 3, and the other end of the secondary crack 4 is connected to the liquid outlet pipe 2. The width of the secondary crack 4 gradually decreases from 6 mm to 4 mm along the end connected to the main crack 3 to the end connected to the liquid outlet pipe 2; one end of the tertiary crack 5 is connected to the secondary crack 4, and the width of the tertiary crack 5 gradually decreases from 4 mm to 2 mm along the end connected to the secondary crack 4 to the end connected to the liquid outlet pipe 2.

[0039] This embodiment also provides an experimental method for simulating a fracturing network, comprising the following steps:

[0040] a. Assemble the experimental device for simulating the fracturing network, check the air tightness of each part, prepare the experimental materials required for the experiment, and install sensors and cameras;

[0041] b. Prepare fracturing fluid in the liquid preparation tank 9 and put the proppant into the automatic sand adding device 18;

[0042] c. Turn on the screw pump 12 to pump the fracturing fluid into the visualized flat plate model, so that the fracturing fluid is filled in the visualized flat plate model;

[0043] d. According to the sand ratio required by the experiment, a proppant is configured in the sand mixing tank 10;

[0044] e. Pump the proppant into the visualized flat plate model through the screw pump 12. The proppant settles in the primary fracture 3, the secondary fracture 4 and the tertiary fracture 5 through the visualized flat plate model to form a sand bank. The fracturing fluid returns to the fluid supply and sand mixing system through the fluid outlet pipe 2;

[0045] f. Turn on the camera to record the dynamic changes of the sand bank;

[0046] g. After the proppant laying experiment is completed, the clean water in the clean water tank 8 is pumped into the visualization flat plate model through the screw pump 12 to clean the visualization flat plate model.

[0047] In order to study the effect of different proppant mesh sizes on the morphology of the main fracture sand bank in vertical well fracturing, proppant mesh sizes of 10-30 and 80-100 were used respectively. The sand banks formed by the two proppant mesh sizes are shown in Figure 2. Figure 5 As shown, through Figure 5 It can be seen that the laying uniformity of high-mesh proppant is greater than that of low-mesh proppant, which means that the smaller the proppant particle size, the longer the migration distance in the fracture and the more uniform the laying.

[0048] Comparative Example

[0049] Different from the first embodiment, the main cracks, secondary cracks and tertiary cracks of the comparative example are all cracks of equal width, with the width of the main cracks being 8 mm, the width of the secondary cracks being 6 mm, and the width of the tertiary cracks being 4 mm.

[0050] The main crack sand bank morphology formed in Example 1 and the comparative example is shown in the figure Fig. 9 As shown, the dotted line is the sand bank morphology diagram formed in Example 1, and the solid line is the sand bank morphology diagram formed in the comparative example. Fig. 9 It can be seen that the sand bank formed by the comparative example is higher than the sand bank formed by the first embodiment, that is, the height of the sand bank formed by equal-width cracks is too large, which is not conducive to truly reflecting the actual crack laying height, resulting in high simulation parameter results and unable to truly reflect the actual effective crack length and height.

[0051] In addition, combined with the similarity criterion, the fracture half-length was inverted using the fracturing design software from the laboratory test data and compared with the microseismic monitoring fracture parameters to obtain the fracture parameter comparison table shown in Table 1.

[0052] Table 1- Comparison of crack parameters

[0053] Comparative Example Embodiment 1 Microseismic testing Main crack half length 121m 80m 83m

[0054] The above table shows that the inversion result of Example 1 is closer to the microseismic monitoring data, and the result of the simulation calculation of the comparative example is higher, which further proves that the unequal width crack model designed by the present invention can better reflect the actual crack morphology and the simulation result is more accurate.

[0055] Embodiment 2

[0056] like Figure 6 As shown, an experimental device for simulating a fracturing network includes a fluid supply and sand mixing system, a pumping device and a visual flat plate model.

[0057] The liquid supply and sand mixing system includes a clean water tank 8, a liquid preparation tank 9, a sand mixing tank 10, a pump 11 and an automatic sand adding device 18. The outlet of the liquid preparation tank 9 is connected to the inlet of the sand mixing tank 10 through the pump 11. The outlet of the clean water tank 8 and the outlet of the sand mixing tank 10 are both connected to the inlet of the pumping device. The pumping device of this embodiment is a screw pump 12. The automatic sand adding device 18 is connected to the inlet of the sand mixing tank 10 and can automatically add sand to the sand mixing tank 10.

[0058] A liquid inlet pipe 1 and a liquid outlet pipe 2 are provided on the visualized flat plate model. The outlet of the liquid supply and sand mixing system is connected to the liquid inlet pipe 1 through a screw pump 12, and the liquid outlet pipe 2 is connected to the inlet of the liquid supply and sand mixing system.

[0059] The visualized flat plate model includes multiple model units, which include a frame 13, a pressure plate 14, a transparent plate 15 and a sealing strip 16. The transparent plate 15 is provided with two pieces and embedded in the frame 13. The sealing strip 16 is provided between the upper and lower edges of the two transparent plates 15. The pressure plate 14 is connected to the frame 13 by bolts and fixes the transparent plate 15 in the frame 13. The model units are connected by a multi-way joint 17.

[0060] A conical surface is provided on the inner side of the transparent plate 15, and a main crack 3, a secondary crack 4 and a tertiary crack 5 are formed between the two transparent plates 15. Two main cracks 3, two secondary cracks 4 and three-level cracks 5 are provided respectively and are symmetrically arranged. The liquid inlet pipe 1 is arranged between the two main cracks 3, and the liquid inlet pipe 1 simulates a vertical wellbore, and adopts the controllable perforation position physical simulation wellbore disclosed in CN109057787A, and is provided with simulated perforations 6. The visualized flat plate model of this embodiment is used to simulate the double-wing hydraulic fracture network of a vertical well.

[0061] The two ends of the main crack 3 are connected to the liquid inlet pipe 1 and the liquid outlet pipe 2 respectively, and the width of the main crack 3 gradually decreases from 8 mm to 6 mm from the end connected to the liquid inlet pipe 1 to the end connected to the liquid outlet pipe 2. One end of the secondary crack 4 is connected to the main crack 3, and the other end of the secondary crack 4 is connected to the liquid outlet pipe 2. The width of the secondary crack 4 gradually decreases from 6 mm to 4 mm from the end connected to the main crack 3 to the end connected to the liquid outlet pipe 2; one end of the tertiary crack 5 is connected to the secondary crack 4, and the width of the tertiary crack 5 gradually decreases from 4 mm to 2 mm from the end connected to the secondary crack 4 to the end connected to the liquid outlet pipe 2.

[0062] Embodiment 3

[0063] like Figure 7 As shown, an experimental device for simulating a fracture network includes a fluid supply and sand mixing system, a pumping device, a visualized flat plate model and a horizontal well 7.

[0064] The liquid supply and sand mixing system includes a clean water tank 8, a liquid preparation tank 9, a sand mixing tank 10, a pump 11 and an automatic sand adding device 18. The outlet of the liquid preparation tank 9 is connected to the inlet of the sand mixing tank 10 through the pump 11. The outlet of the clean water tank 8 and the outlet of the sand mixing tank 10 are both connected to the inlet of the pumping device. The pumping device of this embodiment is a screw pump 12. The automatic sand adding device 18 is connected to the inlet of the sand mixing tank 10 and can automatically add sand to the sand mixing tank 10.

[0065] A liquid inlet pipe 1 and a liquid outlet pipe 2 are provided on the visualized flat plate model. The outlet of the liquid supply and sand mixing system is connected to the horizontal well 7 through a screw pump 12. The horizontal well 7 is connected to the liquid inlet pipe 1. The liquid outlet pipe 2 is connected to the inlet of the liquid supply and sand mixing system.

[0066] The visualized flat plate model includes multiple model units, which include a frame 13, a pressure plate 14, a transparent plate 15 and a sealing strip 16. The transparent plate 15 is provided with two pieces and embedded in the frame 13. The sealing strip 16 is provided between the upper and lower edges of the two transparent plates 15. The pressure plate 14 is connected to the frame 13 by bolts and fixes the transparent plate 15 in the frame 13. The model units are connected by a multi-way joint 17.

[0067] A conical surface is provided on the inner side of the transparent plate 15, and a main crack 3, a secondary crack 4 and a tertiary crack 5 are formed between the two transparent plates 15. Two main cracks 3, two secondary cracks 4 and two tertiary cracks 5 are provided respectively and are symmetrically arranged. The liquid inlet pipe 1 is arranged between the two main cracks 3. The visualized flat plate model of this embodiment is used to simulate the double-wing hydraulic fracture network of a horizontal well.

[0068] The two ends of the main crack 3 are connected to the liquid inlet pipe 1 and the liquid outlet pipe 2 respectively, and the width of the main crack 3 gradually decreases from 8 mm to 6 mm from the end connected to the liquid inlet pipe 1 to the end connected to the liquid outlet pipe 2. One end of the secondary crack 4 is connected to the main crack 3, and the other end of the secondary crack 4 is connected to the liquid outlet pipe 2. The width of the secondary crack 4 gradually decreases from 6 mm to 4 mm from the end connected to the main crack 3 to the end connected to the liquid outlet pipe 2; one end of the tertiary crack 5 is connected to the secondary crack 4, and the width of the tertiary crack 5 gradually decreases from 4 mm to 2 mm from the end connected to the secondary crack 4 to the end connected to the liquid outlet pipe 2.

[0069] In order to study the effect of different fracture flow velocities on the morphology of sand banks in secondary fractures during horizontal well fracturing, the fracture flow velocities of 0.4 m / s and 0.63 m / s were used respectively. The sand banks formed by the two fracture flow velocities are shown in Figure 2. Figure 8 As shown, through Figure 8 It can be seen that when the flow rate is higher, that is, when the fracturing displacement is larger, the proppant migration distance is longer.

[0070] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention.

Claims

1. An experimental device for simulating a fracturing network, comprising a liquid supply and sand mixing system, a pumping device and a visual flat plate model, wherein the visual flat plate model is provided with a liquid inlet pipe (1) and a liquid outlet pipe (2), the outlet of the liquid supply and sand mixing system is connected to the liquid inlet pipe (1) through the pumping device, and the liquid outlet pipe (2) is connected to the inlet of the liquid supply and sand mixing system, characterized in that: The visualized flat plate model is provided with a main crack (3), a secondary crack (4) and a tertiary crack (5); the two ends of the main crack (3) are respectively connected to a liquid inlet pipe (1) and a liquid outlet pipe (2); the width of the main crack (3) gradually decreases from the end connected to the liquid inlet pipe (1) to the end connected to the liquid outlet pipe (2); one end of the secondary crack (4) is connected to the main crack (3), and the other end of the secondary crack (4) is connected to the liquid outlet pipe (2); the width of the secondary crack (4) gradually increases from the end connected to the main crack (3) to the end connected to the liquid outlet pipe (2). The third-level crack (5) is connected to the second-level crack (4) at one end, and the width of the third-level crack (5) is gradually reduced from the end connected to the second-level crack (4) to the end connected to the liquid outlet pipe (2); the liquid supply and sand mixing system comprises a clean water tank (8), a liquid preparation tank (9), a sand mixing tank (10) and a pump (11); the outlet of the liquid preparation tank (9) is connected to the inlet of the sand mixing tank (10) through the pump (11); the outlet of the clean water tank (8) and the outlet of the sand mixing tank (10) are both connected to the inlet of a pumping device; the pumping device is a screw pump (12).

2. The experimental device for simulating a fracturing network according to claim 1, characterized in that: The main cracks (3), the secondary cracks (4) and the tertiary cracks (5) are each provided with two and are symmetrically arranged.

3. The experimental device for simulating a fracturing network according to claim 1, characterized in that: The main crack (3) is provided with one, and the secondary cracks (4) are provided with two and are arranged at intervals along the length direction of the main crack (3).

4. The experimental device for simulating a fracturing network according to any one of claims 1 to 3, characterized in that: The liquid inlet pipe (1) is provided with simulated perforations (6).

5. The experimental device for simulating a fracturing network according to any one of claims 1 to 3, characterized in that: It also comprises a horizontal well (7), wherein the horizontal well (7) is connected to the liquid inlet pipe (1).

6. The experimental device for simulating a fracturing network according to any one of claims 1 to 3, characterized in that: The visualized flat plate model comprises a plurality of model units, wherein the model units comprise a frame (13), a pressure plate (14), a transparent plate (15) and a sealing strip (16); two transparent plates (15) are provided and embedded in the frame (13); the sealing strip (16) is provided between the upper and lower edges of the two transparent plates; the pressure plate (14) is connected to the frame (13) by bolts and the transparent plate (15) is fixed in the frame (13); the model units are connected by a multi-way joint (17); a conical surface is provided on the inner side of the transparent plate (15); the primary crack (3), the secondary crack (4) and the tertiary crack (5) are formed between the two transparent plates (15).

7. An experimental device for simulating a fracturing network according to any one of claims 1 to 6 and an experimental method for simulating a fracturing network, comprising the following steps: a. According to the experimental requirements, determine the injection method and fracture network form to be simulated, then assemble the experimental device simulating the fracture network, check the air tightness of each part, prepare the experimental materials required for the experiment, and install sensors and cameras; b. Prepare the fracturing fluid through the fluid supply and sand mixing system, and put the proppant into the fluid supply and sand mixing system; c. Turn on the pumping device and pump the fracturing fluid into the visualized flat plate model, so that the fracturing fluid is filled in the visualized flat plate model; d. Configure proppant in the fluid supply and sand mixing system according to the sand ratio required by the experiment; e. Pumping the proppant into the visualized flat plate model through a pumping device. The proppant passes through the visualized flat plate model and settles in the primary fracture (3), the secondary fracture (4) and the tertiary fracture (5) to form a sand bank. The fracturing fluid returns to the fluid supply and sand mixing system through the fluid outlet pipe (2); f. Turn on the camera to record the dynamic changes of the sand bank; g. After the proppant laying experiment is completed, the liquid supply and sand mixing system pumps clean water into the visual flat plate model through a pumping device to clean the visual flat plate model.

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