A visual proppant transport experiment device and method for fractured reservoirs

Abstract

The present application relates to the technical fields of oil and gas stimulation and reconstruction, and discloses a visual proppant migration experimental device for fractured reservoirs, which comprises a control module, a sand mixing tank, a proppant migration chamber, and a waste liquid tank, wherein the proppant migration chamber comprises a general frame A and a general frame B which are arranged in parallel respectively in front and back, and a thickness-adjustable telescopic frame is fixedly connected between the general frame A and the general frame B; the surfaces of the general frame A and the general frame B are respectively provided with a first branch fracture simulation mechanism and a second branch fracture simulation mechanism, and the width of the branch fracture simulation mechanism and the angle of the branch fracture simulation mechanism relative to the general frame A and the general frame B are adjustable; and the present application further discloses an experimental method for operating the above-mentioned visual proppant migration experimental device for fractured reservoirs. The present application can simulate the migration of proppants in the process of hydraulic fracturing of fractured reservoirs, and accurately evaluate the feasibility of the condition in field construction.

Description

Technical Field

[0001] This invention relates to the field of oil and gas production enhancement and modification technology, specifically to a visual proppant migration experimental device and method for fractured reservoirs. Background Technology

[0002] Fractured oil and gas reservoirs are widely distributed in my country and constitute an important part of the country's oil and gas resources. Domestically and internationally, hydraulic fracturing is commonly used to create artificially propped fractures to provide pathways for oil and gas flow. However, due to the development of natural fractures in fractured reservoirs, fracturing fluid is lost along these natural fractures during hydraulic fracturing, easily leading to premature settlement of the proppant near the wellbore. As fracturing continues, proppant accumulates near the wellbore, which can severely cause sand blockage and operational accidents. Therefore, determining appropriate operational parameters, such as sand ratio and displacement rate, under the influence of natural fracture filtration is crucial for safe and efficient hydraulic fracturing operations.

[0003] Chinese patent document with publication number CN211314180U and authorization announcement date of August 21, 2020 discloses a proppant transport simulation device with different seam width combinations. The device includes a visual seam mesh system, a liquid storage and supply system, an automatic sand feeder, a sand mixing tank, a recovery tank, and a numerical control system. The visual sewing mesh system and the CNC system are electrically connected, characterized in that: the liquid storage and supply system is connected to an automatic sand feeder, the automatic sand feeder is connected to a sand mixing tank, the sand mixing tank is connected to the inlet end of the visual sewing mesh system through a first input pipe, the outlet end of the visual sewing mesh system is connected to a recovery tank through a second input pipe, and the recovery tank is connected to the liquid storage and supply system. The visual sewing mesh system includes a main seam, a first branch seam, a second branch seam, a third branch seam, a first micro-crack, a second micro-crack, and a third micro-crack; the connection angle between the first branch seam and the main seam is 120°, the connection angle between the first micro-crack and the first branch seam is 60°, the connection angle between the second micro-crack and the third micro-crack is 120°, the connection angle between the second branch seam and the main seam is 90°, the connection angle between the third branch seam and the main seam is 30°, and the connection angle between the third micro-crack and the third branch seam is 90°. The width of the main seam is 5mm, the width of the first, second, and third branch seams is 2mm, and the width of the first, second, and third micro-cracks is 1mm. The liquid storage and supply system includes a first circulation pump, a first mixing tank, a second mixing tank, and a third mixing tank, arranged side by side. A first solenoid valve is connected to the outlet of the first mixing tank, a second solenoid valve to the outlet of the second mixing tank, and a third solenoid valve to the outlet of the third mixing tank. All three mixing tanks are connected to a recovery tank via the first circulation pump. A valve and a second circulation pump are connected to the recovery tank. A fourth solenoid valve is connected to the first input pipe, and a fifth solenoid valve is connected to the second input pipe. The numerical control system includes a processor, a data acquisition unit electrically connected to the processor, and a video acquisition unit. The data acquisition unit transmits the acquired data to the processor, and the video acquisition unit transmits the images and videos of the support material within each seam acquired by the visualization stitching system to the processor.

[0004] The proppant transport simulation device for different crack width combinations disclosed in this patent document can simulate proppant transport for crack combinations with different crack widths and angles to a certain extent, providing experimental support for the field. However, it cannot change the width of the main crack, the width and angle of the first, second and third branch cracks, and it cannot control the filtration rate of the branch cracks. Therefore, its universality in practical applications is poor. Summary of the Invention

[0005] This invention provides a visual proppant migration experimental device and method for fractured reservoirs, which can effectively simulate the effects of different fracture widths, different natural fracture filtration rates, different natural fracture angles, different sand ratios, and different construction discharge rates on proppant migration and sand embankment distribution morphology within fractures.

[0006] This invention is achieved through the following technical solution:

[0007] A visualization apparatus for proppant migration in fractured reservoirs includes:

[0008] Control module;

[0009] A sand mixing tank is electrically connected to the control module. The output end of the sand mixing tank is connected to the input end of a constant flow pump through a pipeline. A valve A is provided between the sand mixing tank and the constant flow pump. The constant flow pump is electrically connected to the control module.

[0010] The proppant transport chamber is connected to the output end of the constant flow pump via a pipeline;

[0011] The waste liquid tank is connected to the output end of the proppant transport chamber via a pipeline;

[0012] The proppant transport chamber includes a general frame A and a general frame B arranged in parallel front and rear, respectively. A stacked frame with adjustable thickness is fixedly connected between the general frame A and the general frame B. The general frame A and / or the general frame B are provided with an inlet and an outlet. A distance adjustment mechanism for adjusting the thickness of the stacked frame is provided between the general frame A and the general frame B. The surfaces of the general frame A and the general frame B are respectively provided with a first natural crack simulation mechanism and a second natural crack simulation mechanism. The width of the natural crack simulation mechanism and its angle relative to the general frame A and the general frame B are adjustable.

[0013] As an optimization, an upper tempered glass plate A is embedded in the upper middle part of the overall frame A, and a lower tempered glass plate A is embedded in the lower middle part of the overall frame A. The situation within the space enclosed by the overall frame A, the overall frame B, and the stacked frame can be seen through the upper tempered glass plate A and the lower tempered glass plate A. The first natural crack simulation mechanism is located on the overall frame A between the upper tempered glass plate A and the lower tempered glass plate A.

[0014] As an optimization, the first natural crack simulation mechanism includes at least one first shapeable metal hose, on which a first flow meter is installed, and a first valve is provided between the first flow meter and the overall frame A. The first shapeable metal hose is detachably connected to the surface of the overall frame A, and the interior of the first shapeable metal hose is in communication with the space enclosed by the overall frame A, the overall frame B, and the stacked frame.

[0015] As an optimization, an upper tempered glass plate B is embedded in the upper middle part of the overall frame B, and a lower tempered glass plate B is embedded in the lower middle part of the overall frame B. The situation within the space enclosed by the overall frame A, the overall frame B, and the stacked frame can be seen through the upper tempered glass plate B and the lower tempered glass plate B. The second natural crack simulation mechanism is located on the overall frame B between the upper tempered glass plate B and the lower tempered glass plate B.

[0016] As an optimization, the second natural crack simulation mechanism includes at least one second shapeable metal hose, on which a second flow meter is installed, and a second valve is provided between the second flow meter and the overall frame B. The second shapeable metal hose is detachably connected to the surface of the overall frame B, and the interior of the second shapeable metal hose is in communication with the space enclosed by the overall frame A, the overall frame B, and the stacked frame.

[0017] As an optimization, the distance adjustment mechanism includes at least four screws that are perpendicularly disposed through the surfaces of the overall frame A and the overall frame B. The at least four screws are respectively located at the four corners of the overall frame A. A first nut is threaded to one end of each screw extending out of the surface of the overall frame A, and a second nut is threaded to one end of each screw extending out of the surface of the overall frame B.

[0018] As an optimization, the liquid inlet is located above the upper tempered glass plate A or the upper tempered glass plate B, and the liquid outlet is located below the lower tempered glass plate A or the lower tempered glass plate B.

[0019] As an optimization, the connection method between the first shapeable metal hose and the overall frame A includes, but is not limited to, threaded connection or snap-fit.

[0020] As an optimization, the connection method between the second shapeable metal hose and the overall frame B includes, but is not limited to, threaded connection or snap-fit.

[0021] The present invention also discloses an experimental method for operating the above-described visual proppant migration experimental apparatus for fractured reservoirs, comprising:

[0022] S1. Close valve A, the first valve and the second valve, and adjust the distance between the overall frame A and the overall frame B through the distance adjustment mechanism so that the distance between the overall frame A and the overall frame B is consistent with the width of the main crack;

[0023] S2. Select a first natural crack simulation mechanism and a second natural crack simulation mechanism with appropriate widths and manually adjust the angles of the first natural crack simulation mechanism and the second natural crack simulation mechanism relative to the overall frame A and the overall frame B so that the angles of the first natural crack simulation mechanism and the second natural crack simulation mechanism relative to the overall frame A and the overall frame B are consistent with the angles of the branch cracks relative to the main crack.

[0024] S3. Pour the fracturing fluid and proppant into the mixing tank and stir to form a mixture. Adjust the speed of the constant flow pump so that the speed at which the constant flow pump delivers the mixture is consistent with the calculated laboratory injection displacement.

[0025] S4. Open the first and second valves halfway, then open valve A and observe the changes in the readings of the first and second flow meters. After the readings of the first and second flow meters stabilize, calculate the filtration rate of the natural crack.

[0026] S5. After the mixture has been transported, close valve A, the first valve and the second valve, and then record the accumulation morphology of the sand embankment in the proppant transport chamber.

[0027] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0028] This invention utilizes a stacked frame to simulate different in-situ fracture widths and a shapeable metal hose with a valve to simulate the filtration loss of natural fractures at different angles. Then, proppant migration experiments are carried out under different test conditions (sand ratio, proppant type, displacement) to realistically simulate the proppant migration during hydraulic fracturing of fractured reservoirs and accurately evaluate the feasibility of this condition in in-situ construction. Attached Figure Description

[0029] To more clearly illustrate the technical solutions of the exemplary embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be considered as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort. In the drawings:

[0030] Figure 1 This is a schematic diagram of the structure of a visual proppant migration experimental device for fractured reservoirs according to the present invention;

[0031] Figure 2 for Figure 1 A three-dimensional view of the proppant transport chamber in the image;

[0032] Figure 3 for Figure 2 The front view;

[0033] Figure 4 for Figure 2 Rear view;

[0034] Figure 5 for Figure 2 Top view;

[0035] Figure 6 for Figure 2 A schematic diagram of the stacked frame structure.

[0036] The attached diagram shows the markings and corresponding component names:

[0037] 1—Control Module; 2—Mixing Tank; 3—Valve A; 4—Constant Flow Pump; 5—Stacked Frame; 6—Overall Frame A; 7—Overall Frame B; 8—Nut A; 9—Screw A; 10—Nut B; 11—Inlet; 12—Nut C; 13—Screw B; 14—Nut D; 15—Nut E; 16—Screw C; 17—Nut F; 18—Outlet; 19—Nut G; 20—Screw D; 21—Nut H; 22—Upper Tempered Glass Plate A; 23—Upper Tempered Glass Plate B; 24—Lower Tempered Glass Plate A; 25—Lower Tempered Glass Plate B; 26—Valve B; 27—Flow Meter A; 28—[Unclear text - likely a continuation of the previous sentence] Shaped metal hose A; 29—Valve C; 30—Flow meter B; 31—Shapeable metal hose B; 32—Valve D; 33—Flow meter C; 34—Shapeable metal hose C; 35—Valve E; 36—Flow meter D; 37—Shapeable metal hose D; 38—Valve F; 39—Flow meter E; 40—Shapeable metal hose E; 41—Valve G; 42—Flow meter F; 43—Shapeable metal hose F; 44—Valve H; 45—Flow meter G; 46—Shapeable metal hose G; 47—Valve I; 48—Flow meter H; 49—Shapeable metal hose H; 50—Waste liquid tank. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention.

[0039] Example 1

[0040] A visualization apparatus for proppant migration in fractured reservoirs includes:

[0041] Control module 1; In this embodiment, control module 1 can be a computer;

[0042] The sand mixing tank 2 is electrically connected to the control module 1. The output end of the sand mixing tank 2 is connected to the input end of the constant flow pump 4 through a pipeline. A valve A 3 is provided between the sand mixing tank 2 and the constant flow pump 4. The constant flow pump 4 is electrically connected to the control module 1.

[0043] Specifically, the upper part of the sand mixing tank 2 is equipped with an agitator, which is electrically connected to the control module 1, and the lower part of the sand mixing tank 2 is connected to valve A 3 through a pipeline.

[0044] The proppant transport chamber is connected to the output end of the constant flow pump 4 via a pipeline;

[0045] Waste liquid tank 50 is connected to the output end of the proppant transport chamber via a pipeline;

[0046] The proppant transport chamber comprises a main frame A 6 and a main frame B 7 arranged parallel to each other at the front and rear, respectively. An adjustable-thickness stacked frame 5 is fixedly connected between the main frames A 6 and B 7. Specifically, the main frames A 6 and B 7 are fixedly connected to the stacked frame 5 by welding. The stacked frame 5 is a folded frame, and the spacing between the main frames A and B can be adjusted by stretching or compressing it. During the actual operation of the experimental device, the proppant placement pattern within the fracture is simulated under different main fracture widths.

[0047] The overall frame A 6 and / or the overall frame B 7 are provided with a liquid inlet 11 and a liquid outlet 18, such as Figure 2-4 As shown, the liquid inlet 11 is located at the upper right of the overall frame B 7, and the liquid outlet 18 is located at the lower right of the overall frame A 6. Of course, the liquid inlet 11 only needs to be higher than the liquid outlet 18. The specific direction in which it is located in the overall frame A 6 and / or the overall frame B 7 is not limited.

[0048] A distance adjustment mechanism for adjusting the thickness of the stacked frame 5 is provided between the overall frame A 6 and the overall frame B 7, and a first natural crack simulation mechanism and a second natural crack simulation mechanism are respectively provided on the surfaces of the overall frame A 6 and the overall frame B 7, and the width of the natural crack simulation mechanism and the angle relative to the overall frame A 6 and the overall frame B 7 are adjustable.

[0049] In this technical solution, the control module 1 controls the mixing tank 2 to stir and mix the fracturing fluid and proppant. Then, the constant flow pump 4 delivers the mixture of fracturing fluid and proppant to the proppant transport chamber. The enclosed space formed by the overall frame A 6, the overall frame B 7, and the stacked frame 5 is regarded as the main fracture. The first natural fracture simulation mechanism and the second natural fracture simulation mechanism are regarded as natural fractures connected to the main fracture. The angle and width of the natural fracture simulation mechanism can be set according to the actual situation of the natural fracture being simulated.

[0050] In this embodiment, an upper tempered glass plate A22 is embedded in the upper middle part of the overall frame A6, and a lower tempered glass plate A24 is embedded in the lower middle part of the overall frame A6. The situation within the space enclosed by the overall frame A6, the overall frame B7, and the stacked frame 5 can be seen through the upper tempered glass plate A22 and the lower tempered glass plate A24. This allows the staff to dynamically and visually observe the proppant movement and placement during equipment operation. The first natural crack simulation mechanism is located on the overall frame A6 between the upper tempered glass plate A22 and the lower tempered glass plate A24.

[0051] Similarly, an upper tempered glass plate B23 is inlaid in the upper middle part of the overall frame B7, and a lower tempered glass plate B25 is inlaid in the lower middle part of the overall frame B7. The situation within the space enclosed by the overall frame A6, the overall frame B7, and the stacked frame 5 can be seen through the upper tempered glass plate B23 and the lower tempered glass plate B25. This allows the staff to dynamically and visually observe the proppant movement and placement during equipment operation. The second natural crack simulation mechanism is located on the overall frame B7 between the upper tempered glass plate B23 and the lower tempered glass plate B25.

[0052] In this embodiment, the first natural crack simulation mechanism includes at least one first shape-measuring metal hose.

[0053] A first flow meter is installed on the first shapeable metal hose, and a first valve is provided between the first flow meter and the overall frame A6. The first shapeable metal hose is detachably connected to the surface of the overall frame A6, and the interior of the first shapeable metal hose is in communication with the space enclosed by the overall frame A6, the overall frame B7, and the stacked frame 5. The connection method between the first shapeable metal hose and the overall frame A6 includes, but is not limited to, threaded connection or snap-fit.

[0054] Specifically, such as Figure 3As shown, the first natural crack simulation mechanism includes a shapeable metal hose A 28 (equipped with valve B26 and flow meter A 27), a shapeable metal hose C 34 (equipped with valve D 32 and flow meter C 33), a shapeable metal hose E 40 (equipped with valve F 38 and flow meter E 39), and a shapeable metal hose G 46 (equipped with valve H 44 and flow meter G 45);

[0055] In this embodiment, the second natural crack simulation mechanism includes at least one second shapeable metal hose, on which a second flow meter is installed, and a second valve is provided between the second flow meter and the overall frame B7. The second shapeable metal hose is detachably connected to the surface of the overall frame B7, and the interior of the second shapeable metal hose communicates with the space enclosed by the overall frame A6, the overall frame B7, and the stacked frame 5. The connection method between the second shapeable metal hose and the overall frame B7 includes, but is not limited to, threaded connection or snap-fit.

[0056] Specifically, such as Figure 4 As shown, the second natural crack simulation mechanism includes a shapeable metal hose B 31 (equipped with valve C29 and flow meter B 30), a shapeable metal hose D 37 (equipped with valve E 35 and flow meter D 36), a shapeable metal hose F 43 (equipped with valve G 41 and flow meter F 42), and a shapeable metal hose H 49 (equipped with valve I 47 and flow meter H 48).

[0057] (First and Second) The shapeable metal hose, i.e., natural fractures, simulates natural fractures in the formation. This component can be shaped by bending at a certain angle to simulate the filtration loss of natural fractures at different angles and the influence on the proppant placement pattern within the fracture. (First and Second) The (First and Second) valves on the shapeable metal hose, by controlling their opening degree, simulate the influence of natural fractures on the proppant placement pattern within the fracture at different filtration rates. The flow meter can determine the filtration rate of natural fractures under the current valve opening state.

[0058] In this embodiment, the distance adjustment mechanism includes at least four screws that are perpendicularly disposed through the surfaces of the overall frame A6 and the overall frame B7. The at least four screws are located at the four corners of the overall frame A6. A first nut is threaded to one end of each screw that extends out of the surface of the overall frame A6, and a second nut is threaded to one end of each screw that extends out of the surface of the overall frame B7.

[0059] Specifically, such as Figure 3-4As shown, in this embodiment, there are four screws: screw A9, screw B13, screw C16, and screw D20. There are also four first nuts and four second nuts: nut A8, nut C12, nut E15, and nut G19. The second nuts are nut F17, nut H21, nut D14, and nut B10.

[0060] Example 2

[0061] First, let's introduce the existing parameters of the experiment: the width of the crack in the field is 0.006m, the height is 40m, the dip angle of the natural crack is 60°, and the discharge rate in the field is 8m³. 3 / min, the volume of mixing tank 2 is 0.01m³. 3 The total height of the proppant transport chamber is 0.1m, the slickwater-to-sand ratio is 5%, and the true density of the 40 / 70 mesh proppant is 2.7g / cm³. 3 .

[0062] Next, based on the existing experimental parameters, the experimental calculation parameters were set: According to the Reynolds similarity principle, the laboratory injection displacement = field displacement / (main fracture height × main fracture width × 2) × experimental fracture width × experimental fracture height. Since the experimental fracture width can simulate the field fracture width in the experiment, the laboratory injection displacement = 8 / (2 × 40) × 0.01 = 0.001 m 3 / min; Sand ratio = proppant volume / slickwater volume, mixing tank 2 volume = 40 / 70 mesh quartz sand proppant volume + slickwater volume = 0.05 × slickwater volume + slickwater volume = 0.01m³ 3 Therefore, the volume of the slickwater is 0.0095 m³. 3 40 / 70 mesh quartz sand proppant volume = 0.0005 m³ 3 The weight of 40 / 70 mesh quartz sand proppant = volume of 40 / 70 mesh quartz sand proppant × true density of 40 / 70 mesh quartz sand proppant = 0.0005 × 2.7 = 0.00135t = 1.35kg.

[0063] Next, the specific steps of the experimental method of the present invention will be described in detail.

[0064] S1. Close valve A3. Close the first and second valves and adjust the distance between the overall frame A6 and the overall frame B7 through the distance adjustment mechanism so that the distance between the overall frame A6 and the overall frame B7 is consistent with the width of the main crack.

[0065] That is, close all valves; rotate adjusting nuts A, B, C, D, E, F, G, and H so that the overall frame A6 and overall frame B7 are aligned with a distance of 0.006m at all points. During the experiment, outlet 18 is blocked to prevent the mixture from flowing out of the proppant transport chamber.

[0066] S2. Select a first natural crack simulation mechanism and a second natural crack simulation mechanism with appropriate widths, and manually adjust the angles of the first natural crack simulation mechanism and the second natural crack simulation mechanism relative to the overall frame A6 and the overall frame B7, so that the angles of the first natural crack simulation mechanism and the second natural crack simulation mechanism relative to the overall frame A6 and the overall frame B7 are consistent with the angles of the branch cracks relative to the main cracks.

[0067] Specifically, at the connection points of manually bent shapeable metal hoses A 28, B 31, C 34, D 37, E 40, F 43, G 46, and H 49 with the overall frame A 6 or B 7, the hoses should form a 60° angle with the direction of liquid flow while remaining parallel to the ground, maintaining a straight line from the bend to the outlet.

[0068] S3. Pour the fracturing fluid and proppant into the mixing tank 2 and stir to form a mixture. Adjust the speed of the constant flow pump 4 so that the speed at which the constant flow pump 4 delivers the mixture is consistent with the calculated laboratory injection displacement.

[0069] Specifically, 0.0095m of slick water is configured. 3 Weigh 1.35 kg of 40 / 70 mesh quartz sand proppant, pour both into mixing tank 2, turn on control module 1, turn on the stirring device of mixing tank 2, and set the constant flow pump 4 to a displacement of 0.001 m³ / h. 3 / min.

[0070] S4. Open the first and second valves halfway, then open valve A3 and observe the changes in the readings of the first and second flow meters. After the readings of the first and second flow meters stabilize, calculate the filtration rate of the natural crack.

[0071] Specifically, adjust valves B26, C29, D32, E35, F38, G41, H44, and I47 from closed to partially open, then open valve A3. Observe the changes in the readings of flow meters A27, B30, C33, D36, E39, F42, G45, and H48. After the values ​​stabilize, observe the readings of flow meters A27, B30, C33, D36, E39, F42, G45, and H48. The readings of 48 are recorded as V1, V2, V3, V4, V5, V6, V7, and V8, respectively. Then the filtration rate of the natural crack is V = V1 + V2 + V3 + V4 + V5 + V6 + V7 + V8.

[0072] S5. After the mixture has been transported, close valve A3, the first valve and the second valve, and then record the accumulation morphology of the sand embankment in the proppant transport chamber.

[0073] Specifically, after control module 1 displays that there is no liquid in sand mixing tank 2, the agitator, constant flow pump 4, valves B 26, C 29, D 32, E 35, F 38, G 41, H 44, and I 47 are turned off. A high-definition camera is used to photograph the accumulation morphology of the sand embankment in the proppant transport chamber. The on-site crack width is 0.006m, the height is 40m, the natural crack inclination angle is 60°, and the on-site discharge volume is 8m³. 3 When the sand ratio is 5% and the filtration rate from natural fissures is V, the depositional morphology is as shown in the camera photograph.

[0074] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A visual proppant migration experimental apparatus for fractured reservoirs, characterized in that, include: Control module; A sand mixing tank is electrically connected to the control module. The output end of the sand mixing tank is connected to the input end of a constant flow pump through a pipeline. A valve A is provided between the sand mixing tank and the constant flow pump. The constant flow pump is electrically connected to the control module. The proppant transport chamber is connected to the output end of the constant flow pump via a pipeline; The waste liquid tank is connected to the output end of the proppant transport chamber via a pipeline; The proppant transport chamber includes a main frame A and a main frame B arranged in parallel front and rear, respectively. A stacked frame with adjustable thickness is fixedly connected between the main frame A and the main frame B. The main frame A and / or the main frame B are provided with an inlet and an outlet. A distance adjustment mechanism for adjusting the thickness of the stacked frame is provided between the main frame A and the main frame B. The surfaces of the main frame A and the main frame B are respectively provided with a first natural crack simulation mechanism and a second natural crack simulation mechanism. The width of the natural crack simulation mechanism and its angle relative to the main frame A and the main frame B are adjustable. The first natural crack simulation mechanism includes at least one first shapeable metal hose, on which a first flow meter is installed, and a first valve is provided between the first flow meter and the overall frame A. The first shapeable metal hose is detachably connected to the surface of the overall frame A, and the interior of the first shapeable metal hose is in communication with the space enclosed by the overall frame A, the overall frame B, and the stacked frame. The second natural crack simulation mechanism includes at least one second shapeable metal hose, on which a second flow meter is installed, and a second valve is provided between the second flow meter and the overall frame B. The second shapeable metal hose is detachably connected to the surface of the overall frame B, and the interior of the second shapeable metal hose is in communication with the space enclosed by the overall frame A, the overall frame B, and the stacked frame.

2. The experimental apparatus for visualizing proppant migration in fractured reservoirs according to claim 1, characterized in that, An upper tempered glass plate A is embedded in the upper middle part of the overall frame A, and a lower tempered glass plate A is embedded in the lower middle part of the overall frame A. The situation within the space enclosed by the overall frame A, the overall frame B, and the stacked frame can be seen through the upper tempered glass plate A and the lower tempered glass plate A. The first natural crack simulation mechanism is located on the overall frame A between the upper tempered glass plate A and the lower tempered glass plate A.

3. The experimental apparatus for visualizing proppant migration in fractured reservoirs according to claim 1, characterized in that, An upper tempered glass plate B is embedded in the upper middle part of the overall frame B, and a lower tempered glass plate B is embedded in the lower middle part of the overall frame B. The situation within the space enclosed by the overall frame A, the overall frame B, and the stacked frame can be seen through the upper tempered glass plate B and the lower tempered glass plate B. The second natural crack simulation mechanism is located on the overall frame B between the upper tempered glass plate B and the lower tempered glass plate B.

4. The experimental apparatus for visualizing proppant migration in fractured reservoirs according to claim 1, characterized in that, The distance adjustment mechanism includes at least four screws that are perpendicularly disposed through the surfaces of the overall frame A and the overall frame B. The at least four screws are respectively located at the four corners of the overall frame A. A first nut is threaded to one end of each screw extending out of the surface of the overall frame A, and a second nut is threaded to one end of each screw extending out of the surface of the overall frame B.

5. The experimental apparatus for visualizing proppant migration in fractured reservoirs according to claim 2, characterized in that, The liquid inlet is located above the upper tempered glass plate A or the upper tempered glass plate B, and the liquid outlet is located below the lower tempered glass plate A or the lower tempered glass plate B.

6. The experimental apparatus for visualizing proppant migration in fractured reservoirs according to claim 1, characterized in that, The connection between the first shapeable metal hose and the overall frame A includes threaded connection or snap-fit ​​connection.

7. The experimental apparatus for visualizing proppant migration in fractured reservoirs according to claim 1, characterized in that, The connection method between the second shapeable metal hose and the overall frame B includes threaded connection or snap-fit ​​connection.

8. An experimental method for operating the visual proppant migration experimental apparatus for fractured reservoirs as described in any one of claims 1-7, characterized in that, include: S1. Close valve A, the first valve and the second valve, and adjust the distance between the overall frame A and the overall frame B through the distance adjustment mechanism so that the distance between the overall frame A and the overall frame B is consistent with the width of the main crack; S2. Select a first natural crack simulation mechanism and a second natural crack simulation mechanism with appropriate widths and manually adjust the angles of the first natural crack simulation mechanism and the second natural crack simulation mechanism relative to the overall frame A and the overall frame B so that the angles of the first natural crack simulation mechanism and the second natural crack simulation mechanism relative to the overall frame A and the overall frame B are consistent with the angles of the branch cracks relative to the main crack. S3. Pour the fracturing fluid and proppant into the mixing tank and stir to form a mixture. Adjust the speed of the constant flow pump so that the speed at which the constant flow pump delivers the mixture is consistent with the calculated laboratory injection displacement. S4. Open the first and second valves halfway, then open valve A and observe the changes in the readings of the first and second flow meters. After the readings of the first and second flow meters stabilize, calculate the filtration rate of the natural crack. S5. After the mixture has been transported, close valve A, the first valve and the second valve, and then record the accumulation morphology of the sand embankment in the proppant transport chamber.

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