Proppant migration visualization experiment device for simulating rough fracture wall surface

Abstract

The invention discloses a proppant migration visualization experiment device for simulating a rough crack wall surface, which comprises a first crack model and a second crack model which are oppositely butted to form a crack simulation space, and shafts are respectively arranged on two sides of the first crack model and the second crack model in a central symmetry manner. A fluid medium is input into or output from the crack simulation space; a rectangular metal protective frame, an observation plate, a crack simulation assembly and a frame plate are sequentially assembled on the first crack model and the second crack model from outside to inside; the pressure driving system is used for filling pressure gas between the crack simulation assembly and the observation plate so as to adjust the pressure state of the crack simulation space; the conveying unit is used for conveying a fluid medium into the shaft; the monitoring unit is arranged in the shaft and the crack simulation space and is used for monitoring the crack change and fluid parameters in real time; and the visual recording unit is used for recording the migration and laying state of the fluid medium in the crack simulation space.

Description

Technical Field

[0001] This invention relates to the field of oil and gas reservoir development technology, and specifically to a visual experimental device for simulating proppant migration on rough fractured walls. Background Technology

[0002] Hydraulic fracturing technology, as a key means to increase production and efficiency, largely depends on the effective placement and migration of proppant within fractures. However, existing visualization experimental devices for studying proppant migration patterns still have many shortcomings in simulating real geological conditions and complex engineering environments, greatly limiting the efficiency of translating research results into practical applications. For example, traditional techniques often use smooth glass or plexiglass plates, which cannot reproduce the roughness, unevenness, and heterogeneity of underground fractures, leading to distortion of proppant migration and placement patterns. Secondly, regarding the technical deficiencies of fracture width adjustment mechanisms, existing technologies either have fixed fracture widths or rely on manual mechanical overall adjustment, failing to achieve real-time, dynamic, and precise control of fracture width during experiments, and even less able to simulate the dynamic closure effect of the formation after fracturing. Furthermore, regarding the lack of modularity and scalability, existing devices have integrated structures or complex connections, resulting in difficult cleaning, high costs for modification and upgrades, and difficulty in adapting to different experimental scenarios.

[0003] Therefore, it is necessary to provide a visualization experimental apparatus for simulating proppant transport on rough crack walls to solve the problems mentioned in the background art. Summary of the Invention

[0004] To achieve the above objectives, the present invention provides the following technical solution: a visualization experimental device for simulating proppant transport on a rough crack wall, comprising: a first crack model and a second crack model, which are connected to each other to form a crack simulation space; wells are respectively arranged symmetrically on both sides of the first crack model and the second crack model with respect to the center of the crack simulation space, which are used to realize the input or output of fluid medium into or out of the crack simulation space. The first crack model and the second crack model are assembled from the outside to the inside with a rectangular metal protective frame, an observation plate, a crack simulation component, and a frame plate; the frame plates of the first crack model and the second crack model are connected to each other, and the crack simulation components of the first crack model and the second crack model constitute the crack simulation space; A pressure-driven system is used to inject pressurized gas between the crack simulation component and the observation plate to control the pressure state of the crack simulation space. The conveying unit, whose output end is connected to one side of the well shaft, is used to convey fluid media; The monitoring unit is deployed within the wellbore and the fracture simulation space to monitor the fracture changes and fluid parameters in real time. A visualization recording unit, which is set up in correspondence with the observation structure of the observation board, is used to record the movement and placement of the fluid medium in the crack simulation space.

[0005] Preferably, the crack simulation component includes: an elastic membrane, a simulation layer, and a limiting frame; the elastic membrane is attached to the observation plate, and the simulation layer is installed on the side of the elastic membrane away from the observation plate. The simulation layer is composed of several transparent simulation blocks, each of which can slide relative to the other. The transparent simulation blocks have a rough structure on the side closer to the crack simulation space, and the rough structure is consistent with the shape characteristics of the crack wall of a natural rock slab. The limiting frame is commonly fitted on the outer side of each of the transparent simulation blocks to limit the periphery of each of the transparent simulation blocks. At the same time, the elastic membrane is pressed and limited by the frame plate squeezing the limiting frame.

[0006] Preferably, the rectangular metal protective frame and the frame plate are provided with a number of assembly holes on their edges. The first crack model and the second crack model are fixed by bolts passing through the assembly holes. The rectangular metal protective frame is made of stainless steel.

[0007] Preferably, each of the frame plates is a rectangular frame structure, with semi-circular mounting grooves vertically extending through both sides of the frame plate, and semi-circular limiting steps coaxially extending at both ends of the semi-circular mounting grooves. A liquid inlet groove is provided inside the semi-circular mounting groove facing the inner side of the frame plate, and the liquid inlet groove is connected to the crack simulation space. After the first crack model and the second crack model are installed together, the semi-circular mounting grooves on both sides are spliced ​​together to form a circular mounting hole, and the semi-circular limiting steps on both sides are spliced ​​together to form an annular limiting step.

[0008] Preferably, the wellbore includes a cylinder, a clamping ring, and a baffle. The cylinder is adapted to be installed in a circular mounting hole. The baffle is coaxially fixed to one end of the cylinder and is stopped by the annular limiting step on one side. The other end of the cylinder is provided with an external thread. The clamping ring is screwed to the external thread and is clamped to the annular limiting step on the other side to limit the cylinder axially.

[0009] Preferably, the observation plate is an plexiglass plate or a quartz glass plate, and an air hole is provided through one end of the observation plate facing the adjacent rectangular metal frame. The air hole is connected to the output end of the pressure driving system. A sealing gasket is provided between the mating surfaces of the observation plate and the rectangular metal frame. The sealing gasket is made of silicone rubber and is used to seal the observation plate and the rectangular metal frame.

[0010] Preferably, the transparent simulation block is a square resin block.

[0011] Preferably, the pressure driving system includes a pressure source, an inflation line, a pressure regulating valve, and a pressure sensor; one end of the inflation line is connected to the pressure source, and the other end is connected to the chamber between the elastic membrane and the observation plate through the air hole; the pressure regulating valve and the pressure sensor are connected in series on the inflation line.

[0012] Preferably, the monitoring unit includes a distance monitor and a fluid sensor; the distance monitor is installed on the outside of the observation plate; the opposite end of the transparent simulation block is fitted with a positioning mark that is compatible with the distance monitor; the fluid sensor includes a pressure sensor and a flow rate sensor, which are fixedly installed at the input end of the wellbore.

[0013] Compared with the prior art, the present invention provides a visualization experimental device for simulating proppant transport on rough crack walls, which has the following advantages: Highly realistic simulation of crack morphology and dynamic behavior: This invention uses Brazilian split rock slab imprinting and silicone-resin replication processes to prepare a transparent crack model with realistic rough morphology, effectively restoring the geometric heterogeneity and surface roughness characteristics of underground cracks. The model is divided into independently movable small cubes, and with the help of a Vaseline lubrication and pressure-driven system, the physical simulation of the dynamic opening and closing process of cracks is realized, significantly improving the geological fidelity and simulation accuracy of the experimental device, and providing more realistic geological conditions for the study of proppant migration laws; Multi-parameter controllable experimental conditions and high-precision monitoring capabilities: The device integrates flow rate, pressure sensors, and infrared ranging functions, enabling real-time monitoring of key parameters such as crack width, pumping pressure, and flow rate. It also precisely controls crack dynamic changes through a pressure-driven system. Furthermore, by combining variable control (such as proppant particle size, viscosity, and pump speed), it achieves refined experimental analysis under multi-factor coupling conditions, providing a reliable platform for studying the influence of different engineering parameters on proppant placement patterns and enhancing the scientific rigor and repeatability of the experiments.

[0014] Visualized structure and efficient assembly / disassembly design: Utilizing a transparent resin model, acrylic window, and silicone sealing layer, high-definition observation and recording of the entire proppant migration process are achieved. The modular "U"-shaped frame structure and detachable assembly design facilitate model replacement, cleaning, and structural adjustments, improving experimental efficiency and the versatility of the apparatus. Simultaneously, the symmetrical design ensures the consistency of the crack walls on both sides, reducing experimental errors and facilitating comparative analysis and pattern summarization.

[0015] Integrating pneumatic simulation and fluid pumping system: By driving the dynamic changes of the fracture wall through a pressure-driven system, the response behavior of the fracture under the influence of geostress during actual hydraulic fracturing is simulated, making up for the shortcomings of traditional fixed fracture width models.

[0016] Application Potential and Engineering Guidance Value: This device can systematically study the migration, sedimentation, and placement of proppant in complex fractures, revealing the influence mechanisms of factors such as rough walls and dynamic fracture width on conductivity, providing direct experimental basis for optimizing fracturing design (such as particle size selection and pumping procedures). Its modularity and scalability are also suitable for advanced research such as multi-fracture networks and non-Newtonian fluids, possessing significant scientific research and engineering application value. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of the device of the present invention; Figure 2 This is a schematic diagram of the exploded structure of the first crack model or the second crack model of the present invention; Figure 3 This is a schematic diagram of the frame plate structure of the present invention; Figure 4 This is a schematic diagram of the wellbore structure of the present invention; Figure 5 This is a schematic diagram of the exploded structure of the device of the present invention; In the figure: 1. First fracture model; 2. Second fracture model; 3. Wellbore; 4. Rectangular metal frame; 5. Observation plate; 6. Fracture simulation component; 7. Frame plate; 31. Cylinder; 32. Compression ring; 33. Baffle; 34. Through hole; 51. Vent hole; 61. Elastic membrane; 62. Simulation layer; 63. Limiting frame; 71. Semi-circular mounting groove; 72. Semi-circular limiting step; 73. Liquid inlet groove; 621. Transparent simulation block. Detailed Implementation

[0018] Please see Figure 1-5 The present invention provides a visualization experimental device for simulating proppant transport on a rough fracture wall, comprising: a first fracture model 1 and a second fracture model 2, which are connected to each other to form a fracture simulation space. Wellbores 3 are respectively arranged symmetrically on both sides of the first fracture model 1 and the second fracture model 2 with respect to the center of the fracture simulation space, which are used to realize the input or output of fluid medium (a mixture of proppant, fracturing fluid and proppant) into or out of the fracture simulation space. Specifically, the upper left wellbore 3 of the first fracture model 1 and the second fracture model 2 serve as the input end of the sand-carrying fluid, and the lower right wellbore 3 serves as the output end of the sand-carrying fluid, forming a diagonal fluid circulation path to ensure that the sand-carrying fluid flows fully in the fracture simulation space and avoid proppant deposition distortion caused by local dead corners.

[0019] The first crack model 1 and the second crack model 2 are assembled from the outside to the inside with a rectangular metal protective frame 4, an observation plate 5, a crack simulation component 6, and a frame plate 7; the frame plates 7 of the first crack model 1 and the second crack model 2 are connected to each other, and the crack simulation components 6 of the first crack model 1 and the second crack model 2 form the crack simulation space; the frame plate 7 is a high-strength nylon plate with an overall U-shaped structure, which is used to limit and fix the crack simulation component 6 on the inner side to prevent the component from shifting due to fluid flow or pressure changes; Furthermore, the edges of the rectangular metal protective frame 4 and the frame plate 7 are provided with several assembly holes. The first crack model 1 and the second crack model 2 are fixed by bolts passing through the assembly holes. The rectangular metal protective frame 4 is made of stainless steel and has an overall U-shaped frame to provide rigid support for the internal components and prevent the frame from deforming due to pressure during the experiment.

[0020] Furthermore, the observation plate 5 is an organic glass plate or a quartz glass plate, and each observation plate 5 has a vent 51 extending through one end facing the adjacent rectangular metal frame 4. The vent 51 is connected to the output end of the pressure drive system. A sealing gasket is provided between the mating surfaces of the observation plate 5 and the rectangular metal frame 4. The sealing gasket is made of silicone rubber and is used to seal the observation plate 5 and the rectangular metal frame 4. The sealing gasket is a rubber sealing gasket, and an annular sealing groove is formed on the mating surfaces. The rubber sealing gasket is installed in the annular sealing groove, and a connecting piece passes through the assembly hole to achieve a compression seal, preventing leakage of the medium or sand-carrying liquid. At the same time, the rubber sealing gasket seals the simulated crack space, forming a pressure chamber.

[0021] A pressure-driven system is used to inject pressurized gas between the fracture simulation component 6 and the observation plate 5 to control the pressure state of the fracture simulation space and adapt to formation fractures of different depths. The pressure drive system includes a pressure source, an inflation line, a pressure regulating valve, and a pressure sensor; one end of the inflation line is connected to the pressure source, and the other end is connected to the chamber between the elastic membrane 61 and the observation plate 5 through the air hole 51; the pressure regulating valve and the pressure sensor are connected in series on the inflation line.

[0022] The conveying unit has its output end connected to the wellbore 3 on one side for conveying fluid media; The monitoring unit is deployed in the wellbore 3 and the fracture simulation space to monitor the fracture changes and fluid parameters in real time. A visualization recording unit is provided, which is set in accordance with the observation structure of the observation board 5. The visualization recording unit is a high-speed camera, which is installed on the front and sides of the observation board 5 at an angle to shoot without blind spots, so as to record the movement and laying state of the fluid medium in the crack simulation space.

[0023] It should be explained that the pressure-driven system, the delivery unit, the monitoring unit, and the visualization recording unit are used to dynamically drive deformation in the crack simulation space, stably deliver the sand-carrying fluid, monitor parameters in real time, and record the proppant migration process. The systems and units are connected by cables to form an integrated experimental platform.

[0024] When experiments are required, the first fracture model 1 and the second fracture model 2 are assembled and fixed in layers to ensure the airtightness of the fracture simulation space. A pre-pressurization test is then performed on the fracture simulation space using a pressure-driven system to check for leaks. Next, the pressure-driven system is activated, injecting a pressure medium (compressed air or inert gas) between the observation plate 5 and the fracture simulation component 6. Adjusting the pressure changes the spacing between the fracture simulation components 6, thereby altering the width of the fracture simulation space and simulating the opening and closing process of fractures caused by formation pressure changes. The monitoring unit tracks the fracture width changes in real time until the target fracture width is reached, at which point the pressure is stabilized. Then, the delivery unit is activated, injecting the prepared proppant-carrying fluid (a mixture of fracturing fluid and proppant) into the fracture simulation space at a uniform speed through the wellbore 3 at the input end. The proppant-carrying fluid flows within the fracture, carrying the proppant. During this process, the visualization recording unit captures the proppant's migration trajectory and deposition morphology throughout, while the monitoring unit simultaneously collects parameters such as pressure, flow rate, and fracture width. Finally, after the proppant placement is stable, the delivery unit and pressure drive system are stopped, the proppant-carrying fluid is discharged through the output wellbore 3, the device is disassembled and each component is cleaned, and the monitoring data and visualization records are compiled for subsequent pattern analysis.

[0025] Furthermore, the crack simulation component 6 includes: an elastic membrane 61, a simulation layer 62, and a limiting frame 63; the elastic membrane 61 is attached to the observation plate 5, and the simulation layer 62 is installed on the side of the elastic membrane 61 away from the observation plate 5. The simulation layer 62 is composed of several transparent simulation blocks 621 spliced ​​together. Each transparent simulation block 621 can be slidably arranged relative to the other, and the transparent simulation block 621 has a rough structure on the side close to the crack simulation space. The rough structure is consistent with the shape characteristics of the crack wall of a natural rock slab. Each of the transparent simulation blocks 621 is fitted with a limiting frame 63 on its outer side, which is used to limit the periphery of each of the transparent simulation blocks 621. At the same time, the elastic membrane 61 is pressed and limited by the frame plate 7 pressing the limiting frame 63.

[0026] Specifically, the elastic membrane 61 is made of fluororubber and hydrogenated nitrile rubber, with a thickness of 0.5~2mm. The elastic membrane 61 is pressed by the frame plate 7. Gas is injected into the space between the elastic membrane 61 and the observation plate 5 through the air hole 51 at the output end of the pressure drive system, thereby changing the pressure around the simulated fracture and facilitating the simulation experiment of formation fractures at different depths.

[0027] Furthermore, the transparent simulation block 621 is a square resin block.

[0028] The rough structure of the transparent simulation block 621 is obtained through the following process: A real cracked rock slab from a natural rock formation was selected, and a rock slab sample with a naturally rough surface was obtained using the Brazilian splitting method. Liquid silicone was then cast onto the rough surface of the rock slab sample. After the silicone cured, it was peeled off to obtain a silicone negative mold that perfectly matched the surface of the natural crack. Transparent resin was injected into the silicone negative mold, cured, and then demolded to obtain a resin board with the rough characteristics of a natural crack. Finally, the resin board was cut into 5cm × 5cm cubes to form transparent simulation blocks 621. A thin layer of petroleum jelly was applied to the joint surfaces between the transparent simulation blocks 621 to act as a lubricant, ensuring that the transparent simulation blocks 621 could slide relative to each other under pressure, thus simulating the dynamic deformation of the crack.

[0029] Furthermore, each of the frame plates 7 is a rectangular frame structure, and a semi-circular mounting groove 71 is vertically opened through both sides of the frame plate 7. A semi-circular limiting step 72 is coaxially opened at both ends of the semi-circular mounting groove 71. A liquid inlet groove 73 is opened in the semi-circular mounting groove 71 facing the inside of the frame plate 7. The liquid inlet groove 73 is connected to the crack simulation space. After the first crack model 1 and the second crack model 2 are installed together, the semi-circular mounting grooves 71 on both sides are spliced ​​to form a circular mounting hole, and the semi-circular limiting steps 72 on both sides are spliced ​​to form an annular limiting step.

[0030] Specifically, the inner frame size of the frame plate 7 is adapted to the outer ring size of the simulation layer 62, so that the elastic membrane 61 can be pressed and limited by the frame plate 7 pressing the limiting frame 63.

[0031] Furthermore, the well casing 3 includes a casing 31, a clamping ring 32, and a baffle 33; The cylinder 31 is adapted to be installed in a circular mounting hole. The baffle 33 is coaxially fixed to one end of the cylinder 31 and is stopped by the annular limiting step on one side. The other end of the cylinder 31 is provided with an external thread. The clamping ring 32 is screwed to the external thread and is clamped to the annular limiting step on the other side to limit the cylinder 31 axially. The cylinder 31 is provided with a plurality of through holes 34 longitudinally on the side facing the liquid inlet groove 73.

[0032] It should be explained that the clamping ring 32 and the baffle 33 are fitted with sealing gaskets on the side close to the annular limiting step to prevent leakage of the sand-carrying fluid. After the simulated fracture pressure is adjusted to the appropriate level, the sand-carrying fluid is injected into the wellbore 3 through the delivery unit. The sand-carrying fluid flows into the fracture simulation space through the inlet groove 73 to conduct a fracture fracturing simulation experiment.

[0033] Furthermore, the monitoring unit includes a distance monitor and a fluid sensor; the distance monitor is installed on the outside of the observation plate 5; the opposite end of the transparent simulation block 621 is fitted with a positioning mark that is compatible with the distance monitor (such as an infrared rangefinder); the fluid sensor includes a pressure sensor and a flow velocity sensor, which are fixedly installed at the input end of the wellbore 3.

[0034] Specifically, before the experiment, the initial distance (reference value) of each transparent simulation block 621 was measured using an infrared rangefinder. During the experiment, the infrared rangefinder collected distance data every 10ms, and the displacement of each transparent simulation block 621 was calculated by the difference from the reference value, thereby obtaining the crack width variation data at different locations in the crack simulation space. By integrating the displacement data of all transparent simulation blocks 621, a dynamic deformation distribution map of the crack simulation space was generated, which intuitively reflects the opening and closing state of the crack. The injection pressure and flow rate data of the proppant-carrying fluid were collected in real time using pressure and flow rate sensors, at the same frequency as the infrared rangefinder (collected every 10ms). The collected data was transmitted to a computer terminal via a signal cable and stored synchronously with the crack width data. By analyzing the synergistic relationship between pressure, flow rate, and crack width, the interaction between fluid flow and crack deformation was obtained, providing multi-dimensional data support for the study of proppant migration. The fluid sensors were made of wear-resistant and corrosion-resistant materials (such as stainless steel and ceramic), which can withstand the erosion of proppant particles and ensure the stability of long-term measurements.

[0035] In practice, the first fracture model 1 and the second fracture model 2 are assembled and fixed in layers to ensure the airtightness of the fracture simulation space. A pre-pressurization test is then conducted on the fracture simulation space using a pressure-driven system to check for leaks. Next, the pressure-driven system is activated, injecting a pressure medium (compressed air or inert gas) between the observation plate 5 and the fracture simulation component 6. Adjusting the pressure changes the spacing between the fracture simulation components 6, thereby altering the width of the fracture simulation space and simulating the opening and closing process of fractures caused by formation pressure changes. The monitoring unit tracks the fracture width changes in real time until the target fracture width is reached, at which point the pressure is stabilized. Then, the delivery unit is activated, injecting the prepared proppant-carrying fluid (a mixture of fracturing fluid and proppant) into the fracture simulation space at a uniform speed through the wellbore 3 at the input end. The proppant-carrying fluid flows within the fracture, carrying the proppant. During this process, the visualization recording unit captures the proppant's migration trajectory and deposition morphology throughout, while the monitoring unit simultaneously collects parameters such as pressure, flow rate, and fracture width. Finally, after the proppant placement is stable, the delivery unit and pressure drive system are stopped, the proppant-carrying fluid is discharged through the output wellbore 3, the device is disassembled and each component is cleaned, and the monitoring data and visualization records are compiled for subsequent pattern analysis.

[0036] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A visualization experimental apparatus for simulating proppant transport on rough crack walls, characterized in that, include: The first crack model (1) and the second crack model (2) are connected to each other to form a crack simulation space. Wells (3) are symmetrically arranged on both sides of the first crack model (1) and the second crack model (2) with respect to the center of the crack simulation space, respectively, for realizing the input or output of fluid medium into or out of the crack simulation space. The first crack model (1) and the second crack model (2) are equipped with a rectangular metal protective frame (4), an observation plate (5), a crack simulation component (6) and a frame plate (7) from the outside to the inside; the frame plate (7) of the first crack model (1) and the second crack model (2) are connected to each other, and the crack simulation component (6) of the first crack model (1) and the second crack model (2) constitutes the crack simulation space. A pressure-driven system is used to inject pressurized gas between the crack simulation component (6) and the observation plate (5) to control the pressure state of the crack simulation space; The conveying unit, whose output end is connected to the well barrel (3) on one side, is used to convey fluid medium; The monitoring unit is deployed in the wellbore (3) and the fracture simulation space to monitor the fracture changes and fluid parameters in real time. The visualization recording unit is set in accordance with the observation structure of the observation board (5) and is used to record the movement and laying state of the fluid medium in the crack simulation space.

2. The experimental apparatus for visualizing proppant transport on a rough crack wall according to claim 1, characterized in that, The crack simulation component (6) includes: an elastic membrane (61), a simulation layer (62), and a limiting frame (63); the elastic membrane (61) is attached to the observation plate (5), and the simulation layer (62) is installed on the side of the elastic membrane (61) away from the observation plate (5). The simulation layer (62) is composed of several transparent simulation blocks (621) spliced ​​together. Each transparent simulation block (621) can be slidably arranged relative to the other, and the transparent simulation block (621) has a rough structure on the side close to the crack simulation space. The rough structure is consistent with the shape characteristics of the crack wall of natural rock slab. The limiting frame (63) is commonly fitted on the outside of each of the transparent simulation blocks (621) to limit the periphery of each of the transparent simulation blocks (621). At the same time, the elastic membrane (61) is pressed and limited by the limiting frame (63) squeezed by the frame plate (7).

3. The experimental apparatus for visualizing proppant transport on a rough crack wall according to claim 1, characterized in that, The rectangular metal protective frame (4) and the frame plate (7) are provided with several assembly holes on their edges. The first crack model (1) and the second crack model (2) are fixed by bolts passing through the assembly holes. The rectangular metal protective frame (4) is made of stainless steel.

4. The experimental apparatus for visualizing proppant transport on a rough crack wall as described in claim 1, characterized in that, Each of the frame plates (7) is a rectangular frame structure. A semi-circular mounting groove (71) is vertically opened through both sides of the frame plate (7). A semi-circular limiting step (72) is coaxially opened at both ends of the semi-circular mounting groove (71). A liquid inlet groove (73) is opened inside the semi-circular mounting groove (71) facing the inside of the frame plate (7). The liquid inlet groove (73) is connected to the crack simulation space. When the first crack model (1) and the second crack model (2) are installed together, the semi-circular mounting grooves (71) on both sides are spliced ​​to form a circular mounting hole, and the semi-circular limiting steps (72) on both sides are spliced ​​to form an annular limiting step.

5. The experimental apparatus for visualizing proppant transport on a rough crack wall according to claim 4, characterized in that, The well casing (3) includes a casing (31), a clamping ring (32), and a baffle (33); The cylinder (31) is adapted to be installed in the circular mounting hole. The baffle (33) is coaxially fixed at one end of the cylinder (31) and is stopped by the annular limiting step on one side. The other end of the cylinder (31) is provided with an external thread. The clamping ring (32) is screwed to the external thread and is clamped to the annular limiting step on the other side for axial limiting of the cylinder (31).

6. The experimental apparatus for visualizing proppant transport on a rough crack wall according to claim 2, characterized in that, The observation plate (5) is an organic glass plate or a quartz glass plate. An air hole (51) is provided through one end of the observation plate (5) facing the adjacent rectangular metal frame (4). The air hole (51) is connected to the output end of the pressure drive system. A sealing gasket is provided between the mating surfaces of the observation plate (5) and the rectangular metal frame (4). The sealing gasket is made of silicone rubber and is used to seal the observation plate (5) and the rectangular metal frame (4).

7. The experimental apparatus for visualizing proppant transport on a rough crack wall according to claim 2, characterized in that, The transparent simulation block (621) is a square resin block.

8. The experimental apparatus for visualizing proppant transport on a rough crack wall according to claim 6, characterized in that, The pressure drive system includes a pressure source, an inflation line, a pressure regulating valve, and a pressure sensor; one end of the inflation line is connected to the pressure source, and the other end is connected to the chamber between the elastic membrane (61) and the observation plate (5) through the air hole (51); the pressure regulating valve and the pressure sensor are connected in series on the inflation line.

9. The experimental apparatus for visualizing proppant transport on a rough crack wall according to claim 2, characterized in that, The monitoring unit includes a distance monitor and a fluid sensor; the distance monitor is installed on the outside of the observation plate (5); the opposite end of the transparent simulation block (621) is fitted with a positioning mark to the distance monitor; the fluid sensor includes a pressure sensor and a flow velocity sensor, which are fixedly installed at the input end of the wellbore (3).

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