Visual test system for simulating continuous sand-carrying fracturing

Abstract

The invention provides a visual test system for simulating continuous sand-carrying fracturing, and belongs to the technical field of oil-gas field development. According to the method, the distribution of the proppant in the rock is detected in real time by simulating the whole process of hydraulic fracturing and sand-carrying fracturing of the rock in cooperation with a high-energy CT system, and the dynamic expansion characteristics of a fracture network and the migration and distribution rules of the proppant are obtained; through the permeability detection subsystem, permeability characteristics and flow conductivity change conditions of rocks before and after hydraulic fracturing and before and after sand injection are obtained. Fracturing physical model tests, fracture network feature CT scanning real-time monitoring and rock sample dynamic damage process visualization in different fracturing modes are achieved, and guidance is provided for fracture network morphological feature description, propping agent migration law research, fracturing transformation effect quantitative evaluation and fracturing construction optimization.

Description

Technical Field

[0001] The invention relates to the technical field of oil and gas field development, and in particular to a visual test system for simulating continuous sand-carrying fracturing. Background Art

[0002] The development of unconventional oil and gas resources has become an important development direction of energy development. As the main means of unconventional oil and gas production and production increase, horizontal well volume fracturing is the key technology for optimization of fracturing construction scheme, proppant migration law, and reservoir transformation effect evaluation. However, the key issues such as fracture network characteristics, proppant migration law research, post-fracturing conductivity, and permeability effect evaluation under different fracturing modes are not clearly understood, which seriously restricts the reasonable design of fracturing modes and construction parameters. It is urgent to solve the above technical problems to provide guidance and support for the optimization of unconventional reservoir development plans and increase production and efficiency.

[0003] The prior art has at least the following problems:

[0004] 1. At present, the proppant migration test research uses prefabricated fractured rock samples, mainly to facilitate the proppant to enter and exit the fractures more. In this way, the proppant enters the fracture by natural penetration, which is not easy to enter and the simulation is not realistic;

[0005] 2. Direct sand fracturing, if no main cracks are formed in the rock sample, the proppant will be blocked in the fracturing tube and cannot enter the rock sample, making the simulation unrealistic. Summary of the invention

[0006] In order to solve the problems existing in the prior art, the present invention simulates the whole process of rock hydraulic fracturing and sand-carrying fracturing, cooperates with a high-energy CT system, and detects the distribution of proppants in the rock in real time to obtain the dynamic expansion characteristics of the fracture network, proppant migration and distribution law; through the permeability detection subsystem, the permeability characteristics and conductivity changes of the rock before and after hydraulic fracturing and before and after sand injection are obtained. The fracturing model test under different fracturing modes, the real-time monitoring of fracture network characteristics by CT scanning, and the visualization of the dynamic destruction process of rock samples are realized, providing guidance for the characterization of fracture network morphology characteristics, the study of proppant migration law, the quantitative evaluation of fracturing transformation effect, and the optimization of fracturing construction.

[0007] The present invention provides a visualization test system for simulating continuous sand-carrying fracturing, including a CT scanning and analysis subsystem, a fracturing subsystem, a sand mixing pump subsystem and a permeability detection subsystem;

[0008] The fracturing subsystem and the permeability detection subsystem are both connected to the CT scanning and analysis subsystem;

[0009] The sand mixing pump subsystem is connected to the fracturing subsystem;

[0010] The CT scanning and analysis subsystem simulates the temperature and pressure conditions of the rock sample reservoir, and uses imaging CT to perform real-time scanning during the sand fracturing test to obtain the distribution and flow state of the proppant;

[0011] The fracturing subsystem controls the flow and pressure of the fracturing fluid;

[0012] The sand mixing pump subsystem is used to stir the fracturing fluid and the proppant, and the fracturing fluid and the proppant are fully and evenly mixed by controlling the stirring time and speed;

[0013] The permeability detection subsystem is connected to the CT scanning and analysis subsystem and is used to detect the permeability of rock samples.

[0014] Preferably, the CT scanning and analysis subsystem includes an imaging CT, a fracturing simulation component and a reaction frame base;

[0015] The imaging CT is used to scan the distribution and flow state of the proppant in real time;

[0016] The fracturing simulation component is arranged within the scanning range of the imaging CT and is used to simulate the temperature and pressure environment of the rock sample reservoir;

[0017] The fracturing simulation component is arranged on the reaction frame base.

[0018] Preferably, the fracturing simulation component includes a reaction force frame, a permeable pad, a confining pressure loading cylinder and a high-temperature loading plate; the reaction force frame is arranged at the outermost layer, and the reaction force frame is used to provide a reaction force during confining pressure loading; the confining pressure loading cylinder and the permeable pad are arranged inward in sequence from four planes close to the reaction force frame, the confining pressure loading cylinder is used to provide the confining pressure to which the rock sample is subjected, one side of the permeable pad is used to apply the permeation water pressure, and the permeable pad on the opposite side is used to receive the reverse drainage, and the permeability of the rock sample is calculated by measuring the flow and pressure of the reverse drainage; the high-temperature loading plate is arranged inward close to the permeable pad, and the high-temperature loading plate is used to provide the high temperature to which the rock sample is subjected; the rock sample is placed in the cavity surrounded by the high-temperature loading plate, and a fracturing hole is drilled in the middle of the rock sample.

[0019] Preferably, the rock sample is cubic.

[0020] Preferably, a fracturing hole is drilled in the middle of the cube, and the hole depth is half the side length of the cube.

[0021] Preferably, the permeable pad block on one side is provided with a water injection hole, and the permeable pad block on the other side is provided with a drainage hole.

[0022] Preferably, the permeability detection subsystem is connected to the water injection hole and the drainage hole of the permeable pad.

[0023] Preferably, a water-permeable hole is provided in the middle of the permeable pad block, and water-permeable grooves are evenly distributed on the surface of the permeable pad block.

[0024] Preferably, a water permeable channel is provided inside the permeable pad.

[0025] Preferably, after the infiltrated water enters the water injection hole or the reverse drainage enters the drainage hole, it passes through the permeable channel and the permeable hole and enters the permeable groove to apply infiltrated water pressure or collect the reverse drainage.

[0026] Preferably, the fracturing subsystem comprises a servo motor, a servo motor controller and a multi-link plunger pump, the servo motor controller, the servo motor and the multi-link plunger pump are connected in sequence, and the output of the multi-link plunger pump is fed back to the servo motor controller.

[0027] Preferably, the fracturing fluid flow and fracturing fluid pressure output by the multi-link plunger pump are fed back to the servo motor controller.

[0028] Preferably, the multi-connecting rod piston pump is a crank-connecting rod piston pump.

[0029] Preferably, the sand mixing pump subsystem includes a controller, a motor, a reducer, a motor bracket, a pump body, a stirring paddle, an outer rotor and an inner rotor;

[0030] The controller is connected to the motor, the motor is connected to the reducer, the reducer and the motor are arranged on the motor bracket, and the motor bracket is connected to the reducer and the pump body;

[0031] The outer rotor is connected to the reducer and rotates synchronously with the reducer; the inner rotor rotates along with the outer rotor under the action of magnetic force; the stirring paddle is connected to the inner rotor through the bearing and rotates along with the inner rotor; the blades of the stirring paddle and the stirring rod part on which the blades are mounted are arranged in the pump body, the pump body is used to contain fracturing fluid and proppant, and the pump body is provided with a feed inlet and a liquid outlet.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] (1) The simulated continuous sand-carrying fracturing visualization test system of the present invention adopts a combination of a fracturing subsystem and a sand mixing pump subsystem. The fracturing subsystem is first used to form a main fracture in the rock sample, and then the sand-carrying pump subsystem is used to inject proppant. The proppant can more easily enter the fracturing fracture, thus overcoming the technical difficulty of using prefabricated fractured rock samples in proppant migration test research;

[0034] (2) The present invention simulates the temperature and pressure of deep underground reservoirs, with the temperature loading plate providing the temperature field and the confining pressure loading cylinder providing the pressure, thereby achieving a true simulation of the temperature and pressure environment of the reservoir. The present invention adopts a method in which the CT rotates but the sample does not rotate, so as to perform a three-dimensional CT scanning and reconstruction on the rock sample. During the hydraulic fracturing test, cracks will gradually form inside the rock sample. By using CT to see through the rock sample, the crack expansion process inside the rock can be quantitatively observed. The permeable pad is used as a key component for the post-fracturing permeability measurement. The permeable pad is used to apply water pressure on one surface of the rock sample, and the seepage water pressure and flow rate are detected on the opposite surface. When the seepage flow rate on the opposite side is constant, the permeability of the rock can be calculated. By restoring the fracturing environment to detect the crack expansion and post-fracturing permeability measurement in real time, the degree of reservoir permeability characteristic transformation can be evaluated, the migration law of the proppant in the fracturing crack can be quantitatively studied, technical parameters can be provided for the design of sand-carrying fracturing construction, and guidance can be provided for the characterization of the morphological characteristics of the fracture network, the study of the migration law of the proppant, the quantitative evaluation of the fracturing transformation effect, and the optimization of the fracturing construction. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a general assembly diagram of a simulated continuous sand-carrying fracturing visualization test system according to an embodiment of the present invention;

[0036] Figure 2 It is a block diagram of the working principle of the present invention;

[0037] Figure 3 (a) is a longitudinal cross-sectional structural diagram of a fracturing CT scanning subsystem according to an embodiment of the present invention, and (b) is a stereoscopic diagram of a fracturing CT scanning subsystem according to an embodiment of the present invention;

[0038] Figure 4 (a) is a longitudinal cross-sectional view of a fracturing subsystem according to an embodiment of the present invention, and (b) is a stereoscopic view of a fracturing subsystem according to an embodiment of the present invention;

[0039] Figure 5 (a) is a three-dimensional schematic diagram of a permeable pad block according to an embodiment of the present invention; (b) is a top perspective view of a permeable pad block according to an embodiment of the present invention; (c) is a transverse cross-sectional view of a permeable pad block according to an embodiment of the present invention;

[0040] Figure 6 A schematic diagram of a reaction force frame according to an embodiment of the present invention;

[0041] Figure 7 A schematic diagram of a reaction frame pad according to an embodiment of the present invention;

[0042] Figure 8 A structural diagram of a sand mixing pump subsystem according to an embodiment of the present invention;

[0043] Fig. 9 The present invention is a working principle of a continuous sand-carrying fracturing subsystem according to an embodiment of the present invention.

[0044] In the figure: 10 sand mixing pump subsystem, 20 fracturing subsystem, 30 CT scanning and analysis subsystem, 40 permeability detection subsystem, 11 computer, 12 controller, 13 motor, 14 reducer, 15 motor bracket, 16 outer rotor, 17 pump body, 17-1 feed inlet, 17-2 liquid outlet, 18 stirring rod, 19 blade, 110 inner rotor, 111 bearing; 21 servo motor, 22 multi-link plunger pump, 23 servo motor Machine controller; 31 imaging CT, 32 fracturing simulation component, 33 reaction frame base, 32-1 reaction frame, 32-2 confining pressure loading cylinder, 32-3 rock sample, 32-4 fracturing hole, 32-5 high temperature loading plate, 32-6 permeable pad; 32-6-1 permeable trough, 32-6-2 water injection hole, 32-6-3 permeable channel, 32-6-4 permeable hole, 20-1 fracturing fluid inlet, 20-2 fracturing fluid outlet. DETAILED DESCRIPTION

[0045] The specific implementation modes of the present invention are described in detail below in conjunction with the accompanying drawings.

[0046] The present invention provides a visualization test system for simulating continuous sand-carrying fracturing, comprising a CT scanning and analysis subsystem 30, a fracturing subsystem 20, a sand mixing pump subsystem 10 and a permeability detection subsystem 40;

[0047] The fracturing subsystem 20 and the permeability detection subsystem 40 are both connected to the CT scanning and analysis subsystem 30;

[0048] The sand mixing pump subsystem 10 is connected to the fracturing subsystem 20;

[0049] The CT scanning and analysis subsystem 30 simulates the temperature and pressure conditions of the rock sample 32-3 reservoir, and uses the imaging CT 31 to perform real-time scanning during the sand fracturing test to obtain the distribution and flow state of the proppant;

[0050] The fracturing subsystem 20 controls the flow rate and pressure of the fracturing fluid;

[0051] The sand mixing pump subsystem 10 is used to stir the fracturing fluid and the proppant, and the fracturing fluid and the proppant are fully and evenly mixed by controlling the stirring time and speed;

[0052] The permeability detection subsystem 40 is connected to the CT scanning and analysis subsystem 30 and is used to detect the permeability of the rock sample 32 - 3 .

[0053] According to a specific embodiment of the present invention, the CT scanning and analysis subsystem 30 includes an imaging CT 31, a fracturing simulation component 32, and a reaction frame base 33;

[0054] The imaging CT 31 is used to scan the distribution and flow state of the proppant in real time;

[0055] The fracturing simulation component 32 is arranged within the scanning range of the imaging CT 31 and is used to simulate the temperature and pressure environment of the reservoir of the rock sample 32-3;

[0056] The fracturing simulation component 32 is disposed on the reaction frame base 33 .

[0057] According to a specific embodiment of the present invention, the fracturing simulation component 32 includes a reaction frame 32-1, a permeable pad 32-6, a confining pressure loading cylinder 32-2 and a high temperature loading plate 32-5; the reaction frame 32-1 is arranged at the outermost layer, and the reaction frame 32-1 is used to provide a reaction force during confining pressure loading; the confining pressure loading cylinder 32-2 and the permeable pad 32-6 are sequentially arranged inward from four planes close to the reaction frame 32-1, and the confining pressure loading cylinder 32-2 is used to provide the rock sample 32-3 with a reaction force. The permeable pad 32-6 on one side is used to apply the permeable water pressure, and the permeable pad 32-6 on the opposite side is used to receive the reverse drainage. The permeability of the rock sample 32-3 is calculated by measuring the flow rate and pressure of the reverse drainage. The high-temperature loading plate 32-5 is arranged inwardly close to the permeable pad 32-6, and the high-temperature loading plate 32-5 is used to provide the high temperature to which the rock sample 32-3 is subjected. The rock sample 32-3 is placed in the cavity surrounded by the high-temperature loading plate 32-5, and a fracturing hole 32-4 is drilled in the middle of the rock sample 32-3.

[0058] According to a specific embodiment of the present invention, the rock sample 32-3 is a cube.

[0059] According to a specific embodiment of the present invention, a fracturing hole 32 - 4 is drilled in the middle of the cube, and the depth of the hole is half of the side length of the cube.

[0060] According to a specific embodiment of the present invention, the permeable pad 32-6 on one side is provided with a water injection hole 32-6-2, and the permeable pad 32-6 on the other side is provided with a drainage hole (not shown in the figure).

[0061] According to a specific embodiment of the present invention, the permeability detection subsystem 40 is connected to the water injection hole 32-6-2 and the drainage hole of the permeable pad 32-6.

[0062] According to a specific embodiment of the present invention, a water permeable hole 32-6-4 is provided in the middle of the permeable pad 32-6, and water permeable grooves 32-6-1 are evenly distributed on the surface of the permeable pad 32-6.

[0063] According to a specific embodiment of the present invention, a water permeable channel 32-6-3 is provided inside the permeable pad 32-6.

[0064] According to a specific embodiment of the present invention, after the infiltration water enters the water injection hole 32-6-2 or the reverse drainage enters the drainage hole, it passes through the permeable channel 32-6-3 and the permeable hole 32-6-4 and enters the permeable groove 32-6-1 to apply infiltration water pressure or collect reverse drainage.

[0065] According to a specific embodiment of the present invention, the fracturing subsystem 20 includes a servo motor 21, a servo motor controller 23 and a multi-link plunger pump 22. The servo motor controller 23, the servo motor 21 and the multi-link plunger pump 22 are connected in sequence, and the output of the multi-link plunger pump 22 is fed back to the servo motor controller.

[0066] According to a specific embodiment of the present invention, the fracturing fluid flow rate and fracturing fluid pressure output by the multi-link plunger pump 22 are fed back to the servo motor controller.

[0067] According to a specific embodiment of the present invention, the multi-connecting rod plunger pump 22 is a crank connecting rod plunger pump.

[0068] According to a specific embodiment of the present invention, the sand mixing pump subsystem 10 includes a controller 12, a motor 13, a reducer 14, a motor bracket 15, a pump body 17, a stirring paddle, an outer rotor 16 and an inner rotor 110;

[0069] The controller 12 is connected to the motor 13, the motor 13 is connected to the reducer 14, the reducer 14 and the motor 13 are arranged on the motor bracket 15, and the motor bracket 15 is connected to the reducer 14 and the pump body 17;

[0070] The outer rotor 16 is connected to the reducer 14 and rotates synchronously with the reducer 14; the inner rotor 110 rotates along with the outer rotor 16 under the action of magnetic force; the stirring paddle is connected to the inner rotor 110 through the bearing 111 and rotates along with the inner rotor 110; the blades 19 of the stirring paddle and the stirring rod 18 on which the blades 19 are installed are partially arranged in the pump body 17, and the pump body 17 is used to contain fracturing fluid and proppant, and the pump body 17 is provided with a feed inlet 17-1 and a liquid outlet 17-2.

[0071] Example 1

[0072] According to a specific embodiment of the present invention, the visualized test system for simulating continuous sand-carrying fracturing of the present invention is described in detail below.

[0073] The present invention provides a visualization test system for simulating continuous sand-carrying fracturing, comprising a CT scanning and analysis subsystem 30, a fracturing subsystem 20, a sand mixing pump subsystem 10 and a permeability detection subsystem 40;

[0074] The fracturing subsystem 20 and the permeability detection subsystem 40 are both connected to the CT scanning and analysis subsystem 30;

[0075] The sand mixing pump subsystem 10 is connected to the fracturing subsystem 20;

[0076] The CT scanning and analysis subsystem 30 simulates the temperature and pressure conditions of the rock sample 32-3 reservoir, and uses the imaging CT 31 to perform real-time scanning during the sand fracturing test to obtain the distribution and flow state of the proppant;

[0077] The fracturing subsystem 20 controls the flow rate and pressure of the fracturing fluid;

[0078] The sand mixing pump subsystem 10 is used to stir the fracturing fluid and the proppant, and the fracturing fluid and the proppant are fully and evenly mixed by controlling the stirring time and speed;

[0079] The permeability detection subsystem 40 is connected to the CT scanning and analysis subsystem 30 and is used to detect the permeability of the rock sample 32 - 3 .

[0080] The working principle of the fracturing subsystem 20 is as follows: the operator sets parameters (flow or pressure of fracturing fluid) to the controller through the computer 11, the controller controls the rotation of the servo motor, and the servo motor drives the multi-link plunger pump to work, so as to achieve the purpose of controlling the flow or pressure of fracturing fluid.

[0081] Wherein, the CT scanning and analysis subsystem 30 includes an imaging CT 31, a fracturing simulation component 32 and a reaction frame base 33;

[0082] The imaging CT 31 is used to scan the distribution and flow state of the proppant in real time;

[0083] The fracturing simulation component 32 is arranged within the scanning range of the imaging CT 31 and is used to simulate the temperature and pressure environment of the reservoir of the rock sample 32-3;

[0084] The fracturing simulation component 32 is disposed on the reaction frame base 33 .

[0085] The fracturing simulation component 32 includes a reaction frame 32-1, a permeable pad 32-6, a confining pressure loading cylinder 32-2 and a high temperature loading plate 32-5; the reaction frame 32-1 is arranged at the outermost layer, and the reaction frame 32-1 is used to provide a reaction force during confining pressure loading; the confining pressure loading cylinder 32-2 and the permeable pad 32-6 are sequentially arranged inward from the four planes close to the reaction frame 32-1, and the confining pressure loading cylinder 32-2 is used to provide the confining pressure to the rock sample 32-3, and the permeable pad 32-6 is used to provide the confining pressure to the rock sample 32-3. One side of the pad 32-6 is used to apply osmotic water pressure, and the permeable pad 32-6 on the opposite side is used to receive reverse drainage. The permeability of the rock sample 32-3 is calculated by measuring the flow and pressure of the reverse drainage; the high-temperature loading plate 32-5 is arranged inwardly close to the permeable pad 32-6, and the high-temperature loading plate 32-5 is used to provide the high temperature to which the rock sample 32-3 is subjected; the rock sample 32-3 is placed in the cavity surrounded by the high-temperature loading plate 32-5, and a fracturing hole 32-4 is drilled in the middle of the rock sample 32-3.

[0086] Among them, the rock sample 32-3 in this embodiment is a cube.

[0087] A fracturing hole 32 - 4 is drilled in the middle of the cube, and the depth of the hole is half of the side length of the cube.

[0088] The permeable pad 32-6 on one side is provided with a water injection hole 32-6-2, and the permeable pad 32-6 on the other side is provided with a drainage hole (not shown in the figure).

[0089] The permeability detection subsystem 40 is connected to the water injection hole 32 - 6 - 2 and the drainage hole of the permeable pad 32 - 6 .

[0090] A water-permeable hole 32-6-4 is provided in the middle of the permeable pad 32-6, and water-permeable grooves 32-6-1 are evenly distributed on the surface of the permeable pad 32-6.

[0091] A water permeable channel 32-6-3 is provided inside the permeable pad 32-6.

[0092] After the infiltration water enters the water injection hole 32-6-2 or the reverse drainage enters the drainage hole, it passes through the permeable channel 32-6-3 and the permeable hole 32-6-4 and enters the permeable groove 32-6-1 to apply the infiltration water pressure or collect the reverse drainage.

[0093] The fracturing subsystem 20 includes a servo motor 21, a servo motor controller 23 and a multi-link plunger pump 22. The servo motor controller 23, the servo motor 21 and the multi-link plunger pump 22 are connected in sequence, and the output of the multi-link plunger pump 22 is fed back to the servo motor controller.

[0094] The fracturing fluid flow and fracturing fluid pressure output by the multi-link plunger pump 22 are fed back to the servo motor controller.

[0095] Wherein, the multi-connecting rod plunger pump 22 is a crank connecting rod plunger pump.

[0096] The sand mixing pump subsystem 10 is used to mix the fracturing fluid and the proppant so that the fracturing fluid and the proppant are evenly mixed. The operator sets parameters to the controller through the computer 11 to control the time and speed of mixing. The sand mixing pump subsystem 10 works on the principle of magnetic coupling transmission.

[0097] The sand mixing pump subsystem 10 includes a controller 12, a motor 13, a reducer 14, a motor bracket 15, a pump body 17, a stirring paddle, an outer rotor 16 and an inner rotor 110; the motor 13 and the reducer 14 provide stirring power;

[0098] The controller 12 is connected to the motor 13 , the motor 13 is connected to the reducer 14 , the reducer 14 and the motor 13 are arranged on the motor bracket 15 , and the motor bracket 15 is connected to the reducer 14 and the pump body 17 ; the motor bracket 15 provides a reaction force for the rotation of the motor 13 .

[0099] The outer rotor 16 is connected to the reducer 14 and rotates synchronously with the reducer 14; the inner rotor 110 rotates with the outer rotor 16 under the action of magnetic force, and the actual rotation speed is affected by torque, density of stirring liquid, etc.; the stirring paddle is connected to the inner rotor 110 through the bearing 111 and rotates with the inner rotor 110; the blades 19 of the stirring paddle and the stirring rod 18 on which the blades 19 are installed are partially arranged in the pump body 17, and the stirring rod 18 rotates with the inner rotor 110; the blades 19 are used to stir the fracturing fluid and the proppant. The pump body 17 is used to contain the fracturing fluid and the proppant, and the pump body 17 is provided with an inlet 17-1 and a liquid outlet 17-2, the inlet 17-1 is at the upper part of the pump body 17, and the liquid outlet 17-2 is at the middle position of the pump body 17.

[0100] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A visual test system for simulating continuous sand fracturing, characterized in that: Including CT scanning and analysis subsystem, fracturing subsystem, sand mixing pump subsystem and permeability detection subsystem; The fracturing subsystem and the permeability detection subsystem are both connected to the CT scanning and analysis subsystem; The sand mixing pump subsystem is connected to the fracturing subsystem; The CT scanning and analysis subsystem simulates the temperature and pressure conditions of the rock sample reservoir, and uses imaging CT to perform real-time scanning during the sand fracturing test to obtain the distribution and flow state of the proppant; The fracturing subsystem controls the flow rate and pressure of the fracturing fluid; The sand mixing pump subsystem is used to stir the fracturing fluid and the proppant, and the fracturing fluid and the proppant are fully and evenly mixed by controlling the stirring time and speed; The permeability detection subsystem is connected to the CT scanning and analysis subsystem and is used to detect the permeability of rock samples.

2. The visualization test system for simulating continuous sand fracturing according to claim 1, characterized in that: The CT scanning and analysis subsystem includes an imaging CT, a fracturing simulation component and a reaction frame base; The imaging CT scans the distribution and flow state of the proppant in real time; The fracturing simulation component is arranged within the scanning range of the imaging CT and is used to simulate the temperature and pressure environment of the rock sample reservoir; The fracturing simulation component is arranged on the reaction frame base.

3. The visualization test system for simulating continuous sand fracturing according to claim 1, characterized in that: The fracturing simulation component includes a reaction force frame, a permeable pad, a confining pressure loading cylinder and a high-temperature loading plate; the reaction force frame is arranged in the outermost layer, and the confining pressure loading cylinder and the permeable pad are arranged in sequence from four planes close to the reaction force frame inward; the high-temperature loading plate is arranged inward close to the permeable pad, a rock sample is placed in the cavity surrounded by the high-temperature loading plate, and a fracturing hole is drilled in the middle of the rock sample.

4. The visualization test system for simulating continuous sand fracturing according to claim 3, characterized in that: The rock samples are in the form of cubes.

5. The visualization test system for simulating continuous sand fracturing according to claim 4, characterized in that: A fracturing hole is drilled in the middle of the cube, and the depth of the hole is half the side length of the cube.

6. The visualization test system for simulating continuous sand fracturing according to claim 3, characterized in that: The permeable pad block on one side is provided with a water injection hole, and the permeable pad block on the other side is provided with a drainage hole.

7. The visualization test system for simulating continuous sand fracturing according to claim 6, characterized in that: The permeability detection subsystem is connected to the water injection hole and the drainage hole of the permeable pad.

8. The visualization test system for simulating continuous sand fracturing according to claim 7, characterized in that: A water-permeable hole is arranged in the middle of the permeable pad block, and water-permeable grooves are evenly distributed on the surface of the permeable pad block.

9. The visualization test system for simulating continuous sand fracturing according to claim 8, characterized in that: A water permeable channel is arranged inside the permeable pad.

10. The visualization test system for simulating continuous sand fracturing according to claim 9, characterized in that: After the infiltration water enters the water injection hole or the reverse drainage enters the drainage hole, it passes through the permeable channel and the permeable hole and enters the permeable groove to apply the infiltration water pressure or collect the reverse drainage.

11. The visualization test system for simulating continuous sand fracturing according to claim 1, characterized in that: The fracturing subsystem comprises a servo motor, a servo motor controller and a multi-link plunger pump. The servo motor controller, the servo motor and the multi-link plunger pump are connected in sequence, and the output of the multi-link plunger pump is fed back to the servo motor controller.

12. The visualization test system for simulating continuous sand fracturing according to claim 11, characterized in that: The fracturing fluid flow and fracturing fluid pressure output by the multi-link plunger pump are fed back to the servo motor controller.

13. The visualization test system for simulating continuous sand fracturing according to claim 11, characterized in that: The multi-connecting rod plunger pump is a crank-connecting rod plunger pump.

14. The visualization test system for simulating continuous sand fracturing according to claim 1, characterized in that: The sand mixing pump subsystem includes a controller, a motor, a reducer, a motor bracket, a pump body, a stirring paddle, an outer rotor and an inner rotor; The controller is connected to the motor, the motor is connected to the reducer, the reducer and the motor are arranged on the motor bracket, and the motor bracket is connected to the reducer and the pump body; The outer rotor is connected to the reducer and rotates synchronously with the reducer; the inner rotor rotates along with the outer rotor under the action of magnetic force; the stirring paddle is connected to the inner rotor through a bearing and rotates along with the inner rotor; the blades of the stirring paddle and the stirring rod part on which the blades are installed are arranged in the pump body, the pump body is used to contain fracturing fluid and proppant, and the pump body is provided with a feed inlet and a liquid outlet.

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