A full-automatic sanding simulation experiment device and method with controllable sanding speed

Abstract

The application belongs to the technical field of oil and gas drilling, and particularly relates to a full-automatic sanding simulation experiment device and method with controllable sanding speed. The control system of the application can control the size of the adjustable control valve and the moving speed of the sliding piston through the detection data of the sand amount monitoring system. Since the mortar is in a stirring state, the uniformity of the concentration of the mortar at all places is ensured, the output mortar is uniform and stable, and the purpose of controlling the sanding speed and the sanding concentration is achieved. In addition, for long-period sanding experiments, the application realizes continuous sanding by the alternate working of the sanding main device, and the mortar can be prepared and supplemented by the sand supply system during the experiment, so that the stability of the experiment is ensured.

Description

Technical Field

[0001] This invention belongs to the field of oil and gas drilling technology, specifically relating to a fully automatic sand addition simulation experimental device and method with controllable sand addition speed. Background Technology

[0002] Many of my country's major oil and gas fields, especially offshore oil fields, high-viscosity heavy oil reservoirs, and widely distributed loose sandstone reservoirs, generally face severe sand production challenges. As my country's oil and gas fields gradually enter the mid-to-late stages of development, a large number of complex reservoirs, such as weakly cemented sandstone, deep-water loose reservoirs, and high-temperature, high-pressure heavy oil, are rapidly entering the production stage. These reservoirs generally share the following characteristics: low cementation and poor framework strength; high sensitivity to effective stress; extremely high susceptibility to sand production under production pressure differentials; significant stress concentration near the wellbore, making the formation more prone to fracturing. These factors make sand production problems particularly prominent in offshore oil fields, deep gas reservoirs, and heavy oil cold production wells. In actual production, sand production can cause the following engineering risks:

[0003] (1) Near-wellbore zone fracturing and formation collapse. Sand production may cause wellbore skeleton instability, forming "wormholes", cavities or even large-scale collapse, which seriously damages the reservoir structure.

[0004] (2) A sharp decrease in permeability. Sand migration and blockage can cause a 30%–80% decrease in near-wellbore permeability, affecting production capacity.

[0005] (3) Wellbore equipment erosion. Sand-laden fluids wash over tubing, screens, valves, pumps and other equipment at high speed, causing severe wear and tear and resulting in well shutdowns for repair.

[0006] (4) Insufficient sand-carrying capacity of the wellbore. If sand particles accumulate, it can lead to problems such as tubing blockage, sand accumulation, and sand settling at the bottom of the well.

[0007] Therefore, how to simulate different sand production intensities, concentrations, and velocities under indoor conditions to evaluate sand control methods, sand carrying capacity, and erosion mechanisms is a key aspect of oil and gas production.

[0008] Given the increasingly serious sand production problem in oil and gas fields and the urgent need for sand control, major oilfields and universities in my country have conducted various types of formation sand simulation experiments, including indoor sand-blocking effect evaluation experiments, sand control optimization design experiments, wellbore sand carrying and downhole equipment erosion simulation experiments. These experiments evaluate the proposed sand-blocking media and their precision based on the formation sand particle size characteristics of specific oilfields, and further evaluate sand control methods to optimize specific sand control methods for sand production conditions in a particular reservoir. Furthermore, to ensure production capacity, the selection and control of sand control precision and the evaluation of the dynamic sand carrying capacity of the wellbore are also inseparable from the guidance of indoor experiments for some sand-producing wells. High-quality indoor simulation experiments are an indispensable scientific foundation and engineering guarantee for the successful implementation of sand control strategies and maximizing oil and gas well production capacity and lifespan.

[0009] Indoor experiments require the continuous addition of formation sand to simulate reservoir sand production. However, most existing sand addition methods are still mechanical, semi-automatic, or single-time sand addition methods, which have the following technical drawbacks:

[0010] (1) The sand addition rate is uncontrollable and fluctuates greatly, making it difficult to stabilize the sand concentration. Existing simple thrust or gravity sand addition methods are difficult to maintain a stable sand supply. The sand rate is prone to fluctuation with changes in liquid level, making it impossible to simulate the stable sand production rate of an actual wellbore. Traditional agitated tanks are limited by insufficient agitation power and rapid settling, resulting in uneven sand concentration and large experimental errors.

[0011] (2) The degree of automation is low, and sand supply cannot be continuous and sand addition is easily interrupted. Most devices still require manual control of sand addition time, sand addition amount and device switching. Moreover, the sand addition tank capacity is limited. As the liquid level drops, the sand supply capacity decreases. The experiment requires frequent shutdowns to replenish sand, which is difficult to meet the requirements of long-term experiments.

[0012] Therefore, as oil and gas development moves towards deep water, ultra-deep, and complex reservoirs, scientific research and engineering practice urgently need an experimental device with reliable structure, high degree of automation, strong sand supply capacity, and precise and controllable sand addition speed. Summary of the Invention

[0013] To address the aforementioned technical problems, this invention provides a fully automatic sand addition simulation experimental device and method with controllable sand addition speed. This solves the problems of uncontrollable sand addition speed, insufficient sand supply capacity, frequent manual operation, and poor experimental continuity in existing sand addition devices. It achieves high-precision, high-stability, and fully automatic indoor continuous sand addition simulation of different reservoirs. It can be used for experiments evaluating the sand-blocking medium and sand-blocking accuracy under specific sand production conditions, sand control optimization design experiments, multiphase pipe flow experiments with dynamic sand carrying in wellbore, and downhole equipment erosion simulation experiments, providing experimental foundation support for efficient oil well development.

[0014] The technical problem to be solved by the present invention is achieved by the following technical solution: a fully automatic sand addition simulation experimental device with controllable sand addition speed, comprising a sand addition main device, a sand supply system and a control system;

[0015] The sand supply system is connected to at least two of the sand adding main devices and is used to prepare mortar and supply the prepared mortar to the sand adding main devices;

[0016] The main sand-adding device includes a sand-adding tank, a sand-adding bag, a sliding piston, a first stirrer, and a piston driving device. The sand-adding bag has a bellows-folded structure and is located inside the sand-adding tank. The sliding piston is slidably located inside the sand-adding tank along the axial direction of the sand-adding tank and is connected to the bottom of the sand-adding bag. The first stirrer is located inside the sand-adding bag and at the bottom of the sand-adding bag.

[0017] The piston drive device is connected to the sliding piston and is used to drive the sliding piston to slide along the axial direction of the sand tank.

[0018] The upper end of the sand-adding main device is provided with a sand inlet, and a one-way valve is provided at the sand inlet. The sand supply system is connected to the sand inlet.

[0019] The upper opening of the sand tank is provided with a sand outlet connected to the upper opening of the sand filling bag, and the sand outlet is provided with an adjustable control valve and a sand quantity monitoring device.

[0020] A position sensor is installed at each of the upper and lower ends of the sand adding tank, and the position sensor is used to monitor the position of the sliding piston.

[0021] A pressure sensor is installed on the sand adding tank;

[0022] The control system is connected to the sand supply system, piston drive device, adjustable control valve, sand quantity monitoring device, pressure sensor, and position sensor. This invention's fully automatic sand addition simulation experimental device, with controllable sand addition speed, can simulate the sand production rate and concentration of reservoirs, based on reservoir characteristics, to conduct indoor simulation experiments requiring sand addition. Specifically, the control system can control the size of the adjustable control valve and adjust the movement speed of the sliding piston based on the detection data from the sand quantity monitoring system. Because the slurry is in a stirring state, the uniformity of slurry concentration is ensured, guaranteeing a uniform and stable output of slurry, thereby achieving the goal of controlling the sand addition speed and concentration. For long-cycle sand addition experiments, this invention achieves continuous sand addition through the alternating operation of the main sand addition device. Simultaneously, it allows for the preparation and replenishment of slurry using the sand supply system during the experiment, ensuring experimental stability.

[0023] Preferably, the sand supply system of the present invention includes a sand supply tank, a second agitator and a mortar pump, wherein the second agitator is disposed inside the sand supply tank and the bottom of the sand supply tank is provided with a sand discharge port;

[0024] The sand discharge port of the sand supply tank is connected to the sand inlet, and a mortar pump is installed between the sand discharge port and the sand inlet. This invention utilizes a second agitator to prepare the mortar in the sand supply tank, and uses the mortar pump to pump the prepared mortar from the sand supply tank.

[0025] Preferably, each sand inlet is connected to a sand supply tank via a separate pipe, and each sand inlet corresponds to a mortar pump, which facilitates the adjustment of the mortar entry speed of each sand-adding main device.

[0026] Preferably, the upper end of the sand-adding bladder of the sand-adding main device is provided with a cleaning port, and a one-way valve is provided on the cleaning port;

[0027] A drain pipe with a drain valve is installed at the bottom of the sand supply tank. The sand filling bag can be cleaned using the cleaning port, while the one-way valve ensures the sand filling bag is sealed, preventing mortar leakage. The drain pipe can be used to drain the liquid out of the sand supply tank.

[0028] Preferably, the piston drive device of the present invention includes a bracket, a servo motor, a screw, a ball bearing driver, and a drive gear;

[0029] The drive gear is sleeved on the outside of the ball drive, the ball drive cooperates with the screw, and the upper end of the screw passes through the bottom of the sand tank and is connected to the sliding piston;

[0030] The drive gear is rotatably mounted on the bracket, and the servo motor is fixedly mounted on the bracket. The servo motor drives the drive gear to rotate via a transmission gear. This invention achieves continuously adjustable sand-adding speed and ensures driving precision by using a servo motor to drive a screw that precisely pushes a sliding piston.

[0031] Preferably, the sand-adding tank has a visualization window arranged axially on its side wall. This window allows observation of the sand-adding chamber's condition, preventing damage or deformation that could harm the sliding piston.

[0032] Preferably, the sand outlet is provided with a transparent, pressure-resistant connecting pipe.

[0033] The transparent, pressure-resistant, visually resistant connecting pipe is used to connect the experimental pipeline. The state and concentration of the mortar output from the sand outlet can be observed through this pipe.

[0034] Preferably, the sand-filling bag is made of a composite material of wear-resistant rubber and nylon woven fabric, which makes it more wear-resistant.

[0035] This invention also discloses a fully automatic sand-adding speed controllable sand-adding speed simulation experiment method, which utilizes the aforementioned fully automatic sand-adding speed controllable sand-adding speed simulation experiment device, and includes the following steps:

[0036] S1. Before the experiment begins, add the sand and fluid required for the experiment to the sand supply system and mix the sand liquid evenly. Connect the main sand adding device to the experimental pipeline.

[0037] S2. Open the control system, use the sand supply system to send the sand-liquid mixture into the sand filling bladders of all sand adding main units, and turn on the first agitator in the sand filling bladder.

[0038] S3. The experiment begins. Set the advance speed of the piston drive device, start the pumping program, and the control system automatically opens the adjustable control valve corresponding to one of the sand adding main devices. The sliding piston moves upward, and at the same time, the sand concentration at the sand outlet is detected by the sand quantity monitoring device.

[0039] S4. During the experiment, when the position sensor above the sand-adding main device detects that the sliding piston has reached the preset position, the adjustable control valve on another sand-adding main device will be automatically opened to add sand. At the same time, the sand-adding main device that has completed the sand-adding work will move the sliding piston to the corresponding position of the lower position sensor and use the sand supply system to supply the sand-liquid mixture into the sand-adding bladder of the sand-adding tank.

[0040] Preferably, the present invention further includes the following steps:

[0041] S5. After the experiment, drain the remaining sand-liquid mixture from the sand supply system, rinse it, add clean water, open the adjustable control valve, and introduce the clean water from the sand supply system into the sand filling bag for rinsing.

[0042] Compared with the prior art, the beneficial effects of the present invention are:

[0043] (1) The sand addition rate and sand concentration can be precisely controlled, improving the stability and repeatability of the experiment.

[0044] This invention uses a piston drive device to drive a sliding piston to slide along the axial direction of the sand adding tank, and works in conjunction with a sand quantity monitoring device and a first stirrer to achieve continuous and adjustable sand adding speed and stable output of sand concentration. This significantly reduces the fluctuation of sand liquid flow rate and concentration, improves the stability and repeatability of indoor sand adding experiments, and solves the problems of uncontrollable speed and large concentration fluctuations in traditional sand adding devices.

[0045] This invention utilizes a sandbag to hold mortar, effectively isolating the mortar from the sliding piston and protecting the sliding piston and other driving devices.

[0046] (2) The dual-cylinder automatic switching structure is adopted to achieve long-cycle continuous sand supply.

[0047] This invention connects the sand supply system to at least two main sand-adding devices and links them with position sensors and a control system. When the sand output of one main sand-adding device is nearing completion, the control system automatically switches to another main sand-adding device for output, while simultaneously replenishing sand for the other device, achieving seamless connection of the sand-adding process. This invention enables uninterrupted sand supply for extended periods and is suitable for long-term operating conditions such as multiphase flow sand-carrying experiments, sand-blocking evaluation, and erosion tests.

[0048] (3) Achieve fully automated monitoring and control, significantly reduce human intervention and improve experimental safety.

[0049] This invention sets up monitoring modules for pressure, flow rate, sand concentration, piston position, etc., and realizes automatic judgment, automatic adjustment and abnormal alarm through the control system, which greatly reduces the frequency of manual operation, avoids human error, and improves the safety and control accuracy of the experimental process, providing reliable experimental support for simulating sand production behavior in complex reservoirs. Attached Figure Description

[0050] Figure 1 This is a schematic diagram of the sand-adding simulation experimental device with fully automatic controllable sand-adding speed in this embodiment;

[0051] Figure 2 This is a schematic diagram of the automatic sand-adding main device in this embodiment;

[0052] In the diagram, there is a sand filling tank 1, a sand outlet 101, and a visualization window 102.

[0053] Control system 100;

[0054] Sandbag 2, sand inlet 201, cleaning port 202;

[0055] 3. Sliding piston; 4. First agitator; 5. One-way valve; 6. Adjustable control valve; 7. Position sensor; 8. Sand supply tank; 801. Sand discharge port; 802. Sewage pipe.

[0056] Second mixer 9, mortar pump 10, drain valve 200, bracket 11, servo motor 12, screw 13, drive gear 14, and visual pressure-resistant transparent connecting pipe 15. Detailed Implementation

[0057] The technical solutions in the embodiments of the present invention will now be clearly and completely described in conjunction with the accompanying drawings.

[0058] like Figure 1 and Figure 2 As shown, a fully automatic sand-adding simulation experimental device with controllable sand-adding speed includes a sand-adding main device, a sand supply system, and a control system 100.

[0059] The sand supply system is connected to at least two of the aforementioned sand-adding main devices and is used for preparing mortar and supplying the prepared mortar to the sand-adding main devices. This embodiment designs two independent automatic sand-adding main devices with identical structures, which automatically switch between each other through a control system to ensure continuous sand addition.

[0060] The main sand-adding device includes a sand-adding tank 1, a sand-adding bladder 2, a sliding piston 3, a first stirrer 4, and a piston drive device. The sand-adding bladder 2 has a bellows-like folding structure and is located inside the sand-adding tank 1, capable of extending and retracting along the axial direction of the sand-adding tank 1. The sliding piston 3 is slidably mounted inside the sand-adding tank 1 along the axial direction, and its diameter matches the inner diameter of the sand-adding tank 1. The sealing ring of the sliding piston 3 is made of fluororubber. The sliding piston 3 is connected to the bottom of the sand-adding bladder 2. The first stirrer 4 is located inside the sand-adding bladder 2 and at its bottom. The first stirrer 4 is a small blade stirrer, used to ensure uniform mixing of the sand-liquid mixture in the sand-adding tank during experiments, preventing stratification and sedimentation. Its adjustable speed is 20-200 rpm. Figure 2 As shown, the driving device of the first stirrer 4, such as a motor, is located below the sliding piston 3 and is used to drive the stirring blades inside the sand filling bag 2.

[0061] The sand-adding simulation main unit of this invention serves as the core module, connecting to the experimental pipeline interface via flanges or adapters. It can be linked with the multiphase flow model experimental device, wellbore erosion test pipeline, sand-blocking effect evaluation device, and sand concentration measurement system. The sand supply system, as an auxiliary module, is mainly used to continuously supply slurry to the sand-adding main unit. This invention can maintain uniform mixing of sand and slurry for ≥24 hours.

[0062] The piston drive device is connected to the sliding piston 3 and is used to drive the sliding piston 3 to slide along the axial direction of the sand tank 1.

[0063] The sand inlet 201 is provided at the upper end of the sand inlet 2 of the main sand adding device. A one-way valve 5 is provided at the sand inlet 201, and the sand supply system is connected to the sand inlet 201. The sand inlet 201 is located at the diameter change point at the upper part of the sand adding tank.

[0064] The upper opening of the sand tank 1 is provided with a sand outlet 101 connected to the upper opening of the sand filling bag 2. The sand outlet 101 has a diameter of 40mm. An adjustable control valve 6 and a sand quantity monitoring device are provided at the sand outlet 101. Specifically, the sand quantity monitoring device is a mortar concentration detection device.

[0065] A position sensor 7 is installed at each of the upper and lower ends of the sand tank 1. The position sensor 7 is used to monitor the position of the sliding piston 3.

[0066] A pressure sensor is installed on the sand tank 1.

[0067] The control system 100 is connected to the sand supply system, the piston drive device, the adjustable control valve 6, the sand quantity monitoring device, the pressure sensor, and the position sensor 7, respectively.

[0068] The sand supply system includes a sand supply tank 8, a second agitator 9, and a mortar pump 10. The second agitator 9 is disposed inside the sand supply tank 8, and a sand discharge port 801 is provided at the bottom of the sand supply tank 8. In this embodiment, the second agitator 9 is driven by a servo motor, and the rotation of the servo motor can be controlled by a control system.

[0069] The sand discharge port 801 of the sand supply tank 8 is connected to the sand inlet port 201, and a slurry pump 10 is installed between the sand discharge port 801 and the sand inlet port 201. The sand supply tank 8 is a 316L stainless steel vertical stirring and storage tank with an effective volume of 2000L. The second stirrer 9 uses a double-layer propeller blade to prevent sand settling and has the function of stirring or storing experimental fluids. The slurry pump 10 is a plunger pump with a flow rate of 1-3L / min, and the delivery pipeline uses a combination of wear-resistant flexible hose and metal pipe.

[0070] Each sand inlet 201 is connected to the sand supply tank 8 via a separate pipe, and each sand inlet 201 corresponds to a mortar pump 10.

[0071] The sand-adding main device has a cleaning port 202 at its upper end, and a one-way valve 5 is installed on the cleaning port 202. The cleaning port 202 is located at the diameter change point at the upper part of the sand-adding tank.

[0072] A drain pipe 802 is provided below the sand supply tank 8, and a drain valve 200 is provided on the drain pipe 802.

[0073] The piston drive device includes a bracket 11, a servo motor 12, a screw 13, a ball bearing driver, and a drive gear 14.

[0074] The drive gear 14 is sleeved on the outside of the ball drive, which cooperates with the screw 13. The upper end of the screw 13 passes through the bottom of the sand tank 1 and is connected to the sliding piston 3. The ball drive includes a nut and balls, which are disposed between the nut and the screw 13. The screw 13 can move up and down along the axial direction of the nut. The screw 13 and the ball drive form a screw-ball drive mechanism.

[0075] The drive gear 14 is rotatably mounted on the bracket 11, and the servo motor 12 is fixedly mounted on the bracket 11. The servo motor 12 drives the drive gear 14 to rotate through the transmission gear. The screw 13 has a diameter of 4cm and a pitch of 8mm, providing high driving precision. The adjustment step of the servo motor 12 is 0.01mm. During the experiment, the servo motor is activated to push the sliding piston 3 upward to add sand. The output torque is ≥20N·m, and the speed is adjustable within 10–300rpm. The control system achieves precise control of the sand-adding speed by controlling the speed of the servo motor.

[0076] A visualization window 102 is provided along the axial direction on the side wall of the sand tank 1.

[0077] In this embodiment, the sand filling tank 1 is a 316L stainless steel vertical sand filling tank with a pressure resistance limit of 1MPa. The inner diameter of the sand filling tank 1 is 40cm, and the effective length is 50cm (i.e., the sliding length of the sliding piston 3). The visualization window 102 is made of quartz glass, with a width of 3cm and a height of 50cm (consistent with the sliding range of the sliding piston 3). The visualization window on the surface of the sand filling tank 1 facilitates observation of the dynamics of the bellows folding the sand filling bag.

[0078] A transparent, pressure-resistant connecting pipe 15 is provided at the sand outlet 101.

[0079] The visual pressure-resistant transparent connecting tube 15 is used to connect the experimental pipeline.

[0080] The sand-filled bag 2 is made of a composite material of wear-resistant rubber and nylon woven fabric, and has a pressure resistance of 1.5 MPa.

[0081] This embodiment provides an automatically controlled main sand-addition system. A servo motor controls the pushing speed of the sliding piston 3, simulating different sand production rates and intensities in the reservoir. This achieves precise control of the sand-addition rate and stable control of the sand concentration. It is also equipped with a position monitoring device, a visualization observation unit, and a control system, enabling fully automated and controllable sand-addition and providing support for controlling the sand-addition rate and concentration in indoor sand-addition experiments.

[0082] This invention also provides an automatic sand supply system that operates according to the monitoring device of the main sand adding system. The monitoring device is associated with the slurry pump of the system and can monitor the pressure, flow rate, sand concentration, and piston position in real time, and automatically adjust the system. When the main sand adding device detects that the sand-water mixture is about to be emptied, the slurry pump draws the sand-water mixture from the sand supply system, and at the same time, the sliding piston 3 moves downward to provide a sand source for the experimental sand adding. The monitoring device automatically judges the liquid level and sand quantity, realizing the automatic sand suction and sand replenishment functions.

[0083] like Figure 1As shown, this embodiment provides a dual-cylinder sand adding system consisting of two sand adding main devices, which is connected to a monitoring device and a control system. When the sand adding in one of the sand adding main devices is completed, the control system starts the sand adding main device to replenish the sand-liquid mixture, and starts the other sand adding main device to add sand to the experimental pipeline.

[0084] In this embodiment, the upper position sensor 7 is used to detect the position of the sliding piston 3 after sand delivery, and the upper position sensor 7 is used to detect the initial position of the sliding piston 3. The position sensor 7 is a magnetic or photoelectric sensor. When the upper position sensor 7 detects the sliding piston 3, the servo motor controls the sliding piston 3 to move downwards and simultaneously starts the mortar pump 10 to supply sand to the sand tank 1; when the lower position sensor 7 detects the sliding piston 3, the mortar pump 10 and the servo motor stop running, completing the replenishment of the sand-liquid mixture.

[0085] A fully automatic sand-adding speed controllable sand-adding speed simulation experiment method, utilizing the aforementioned fully automatic sand-adding speed controllable sand-adding speed simulation experiment device, includes the following steps:

[0086] S1. Before the experiment begins, add the required sand and fluid to the sand supply system and mix the sand solution evenly. Connect the main sand adding device to the experimental pipeline.

[0087] S2. Open the control system and use the sand supply system to send the sand-liquid mixture into the sand filling bladders 2 of all sand-adding main devices, and turn on the first agitator 4 inside the sand filling bladders 2.

[0088] S3. The experiment begins. The piston drive device is set to advance speed and the pumping program is started. The control system 100 automatically opens the adjustable control valve 6 corresponding to one of the sand adding main devices. The sliding piston 3 moves upward, and the sand concentration at the sand outlet 101 is detected by the sand quantity monitoring device.

[0089] S4. During the experiment, when the position sensor 7 above the sand-adding main device detects that the sliding piston 3 has reached the preset position, the adjustable control valve 6 on another sand-adding main device is automatically opened to add sand. At the same time, the sand-adding main device that has completed the sand-adding work moves the sliding piston 3 to the corresponding position of the position sensor 7 below, and uses the sand supply system to supply the sand-liquid mixture into the sand-adding bladder 2 of the sand-adding tank 1.

[0090] This embodiment repeats the above steps cyclically, achieving continuous and uninterrupted sand addition, avoiding experimental interruptions, and ensuring continuous and stable pressure, sand concentration, and flow rate.

[0091] The fully automated sand-adding speed controllable sand-adding simulation experiment method further includes the following steps:

[0092] S5. After the experiment, drain the remaining sand-liquid mixture from the sand supply system, rinse it, add clean water, open the adjustable control valve 6, and introduce the clean water from the sand supply system into the sand filling bag 2 for rinsing.

[0093] In this embodiment, a multi-level protection mechanism is also set up, specifically: servo motor overload protection, sand tank pressure limit alarm (>0.8MPa), sand concentration alarm, dual-cylinder switching failure alarm, mortar pump dry run protection, and data disconnection protection. Once an abnormality occurs, the control system automatically closes the adjustable control valve and stops the machine. The above protection mechanism is implemented by collecting relevant signal data. The specific implementation method can be implemented using existing technology, which will not be elaborated here.

Claims

1. A fully automatic sand-adding speed controllable sand-adding simulation experimental device, characterized in that: Includes the main sand-adding device, sand supply system and control system (100); The sand supply system is connected to at least two of the sand adding main devices and is used to prepare mortar and supply the prepared mortar to the sand adding main devices; The main sand-adding device includes a sand-adding tank (1), a sand-adding bag (2), a sliding piston (3), a first stirrer (4), and a piston driving device. The sand-adding bag (2) has a bellows folding structure and is located inside the sand-adding tank (1). The sliding piston (3) is slidably located inside the sand-adding tank (1) along the axial direction of the sand-adding tank (1). The sliding piston (3) is connected to the bottom of the sand-adding bag (2). The first stirrer (4) is located inside the sand-adding bag (2) and at the bottom of the sand-adding bag (2). The piston drive device is connected to the sliding piston (3) and is used to drive the sliding piston (3) to slide along the sand tank (1) axially; The upper end of the sand inlet (2) of the main sand adding device is provided with a sand inlet (201), and a one-way valve (5) is provided at the sand inlet (201). The sand supply system is connected to the sand inlet (201). The upper opening of the sand tank (1) is provided with a sand outlet (101) connected to the upper opening of the sand bag (2), and an adjustable control valve (6) and a sand quantity monitoring device are provided at the sand outlet (101). A position sensor (7) is installed at each of the upper and lower ends of the sand tank (1). The position sensor (7) is used to monitor the position of the sliding piston (3). A pressure sensor is installed on the sand adding tank (1); The control system (100) is connected to the sand supply system, the piston drive device, the adjustable control valve (6), the sand quantity monitoring device, the pressure sensor and the position sensor (7), respectively.

2. The fully automatic sand-adding speed controllable sand-adding simulation experimental device according to claim 1, characterized in that: The sand supply system includes a sand supply tank (8), a second agitator (9) and a mortar pump (10). The second agitator (9) is installed inside the sand supply tank (8), and a sand discharge port (801) is provided at the bottom of the sand supply tank (8). The sand discharge port (801) of the sand supply tank (8) is connected to the sand inlet (201), and a mortar pump (10) is provided between the sand discharge port (801) and the sand inlet (201).

3. The fully automatic sand-adding speed controllable sand-adding simulation experimental device according to claim 2, characterized in that: Each sand inlet (201) is connected to the sand supply tank (8) via a separate pipe, and each sand inlet (201) corresponds to a mortar pump (10).

4. The fully automatic sand-adding speed controllable sand-adding simulation experimental device according to claim 3, characterized in that: The upper end of the sand-adding bladder (2) of the main sand-adding device is provided with a cleaning port (202), and a one-way valve (5) is provided on the cleaning port (202); A drain pipe (802) is provided below the sand supply tank (8), and a drain valve (200) is provided on the drain pipe (802).

5. The fully automatic sand-adding speed controllable sand-adding simulation experimental device according to claim 1, characterized in that: The piston drive device includes a bracket (11), a servo motor (12), a screw (13), a ball drive and a drive gear (14). The drive gear (14) is sleeved on the outside of the ball drive, the ball drive and the screw (13) cooperate with each other, and the upper end of the screw (13) passes through the bottom of the sand tank (1) and is connected to the sliding piston (3). The drive gear (14) is rotatably mounted on the bracket (11), and the servo motor (12) is fixedly mounted on the bracket (11). The servo motor (12) drives the drive gear (14) to rotate through the transmission gear.

6. The fully automatic sand-adding speed controllable sand-adding simulation experimental device according to claim 1, characterized in that: A visualization window (102) is provided along the axial direction on the side wall of the sand tank (1).

7. The fully automatic sand-adding speed controllable sand-adding simulation experimental device according to claim 1, characterized in that: A transparent, pressure-resistant connecting pipe (15) is provided at the sand outlet (101). The visual pressure-resistant transparent connecting tube (15) is used to connect the experimental pipeline.

8. The fully automatic sand-adding speed controllable sand-adding simulation experimental device according to claim 1, characterized in that: The sandbag (2) is made of a composite material of abrasion-resistant rubber and nylon woven fabric.

9. A fully automatic sand-adding speed controllable simulation experiment method, utilizing the fully automatic sand-adding speed controllable simulation experiment device according to any one of claims 1-8, characterized in that, Includes the following steps: S1. Before the experiment begins, add the sand and fluid required for the experiment to the sand supply system and mix the sand liquid evenly. Connect the main sand adding device to the experimental pipeline. S2. Open the control system and use the sand supply system to send the sand-liquid mixture into the sand-adding bladders (2) of all sand-adding main devices, and turn on the first agitator (4) inside the sand-adding bladders (2). S3. At the start of the experiment, the piston drive device is set to advance speed, the pumping program is started, the control system (100) automatically opens the adjustable control valve (6) corresponding to one of the sand adding main devices, the sliding piston (3) moves upward, and the sand concentration at the sand outlet (101) is detected by the sand quantity monitoring device. S4. During the experiment, when the position sensor (7) above the sand-adding main device detects that the sliding piston (3) has reached the preset position, the adjustable control valve (6) on another sand-adding main device will be automatically opened to add sand. At the same time, the sand-adding main device that has completed the sand-adding work will move the sliding piston (3) to the corresponding position of the lower position sensor (7) and use the sand supply system to supply the sand-liquid mixture into the sand-adding bladder (2) of the sand-adding tank (1).

10. The fully automatic sand-adding speed controllable simulation experiment method according to claim 9, characterized in that, It also includes the following steps: S5. After the experiment, drain the remaining sand-liquid mixture in the sand supply system, clean it, add clean water, open the adjustable control valve (6), and introduce the clean water in the sand supply system into the sand filling bag (2) for cleaning.

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