Dynamic leakage stoppage simulation device for wellhead pressure building

Abstract

The invention discloses a dynamic leaking stoppage simulation device for wellhead pressure building, and aims to simulate a dynamic leaking stoppage process in a shaft and related flow characteristics of the dynamic leaking stoppage process. The device comprises a simulation wellbore, a variable-diameter rotating rod, a lifting system, a rotary driving device, a drilling fluid circulating system, a pressure monitoring system, a flow velocity and shear rate detection device, a data acquisition and control system and a core holder system. The shaft is made of transparent materials, and flow characteristics can be observed conveniently; the diameter-adjustable rotating rod and the rotation driving device simulate different drill rod diameters and rotation effects; the drilling fluid circulating system is combined with a pressure regulating valve, a safety valve, a ball valve and a check valve to flexibly control fluid flow and pressure; the data acquisition system realizes parameter monitoring and control; the core clamping system provides a fractured core test. The device can accurately simulate a shaft pressure building environment, enhances experiment flexibility and material performance evaluation capability, and is suitable for plugging technology research and engineering optimization design.

Description

Technical Field

[0001] The invention relates to the technical field of oilfield drilling engineering, and in particular to a dynamic leak plugging simulation device for wellhead pressure holding. Background Art

[0002] With the rapid development of petroleum engineering technology and the increasing complexity of drilling operations, the problem of well leakage has gradually become one of the important challenges that need to be solved first in drilling construction. Well leakage usually refers to the phenomenon that underground fluid enters the wellbore through formation cracks, pores or other defects. This phenomenon will not only cause construction progress delays, but may also cause economic losses, waste of resources and environmental pollution. What is more serious is that under complex geological conditions, traditional plugging methods are difficult to effectively deal with well leakage problems. In particular, the complexity of fracture leakage makes the well leakage problem a bottleneck restricting the efficiency of drilling construction.

[0003] At present, during the drilling construction process, a common solution is to inject materials with plugging properties into the wellbore through the drilling fluid circulation system. These materials usually include graphite particles, calcium carbonate particles and various polymers, which can plug the formation cracks and improve the integrity of the wellbore to a certain extent. However, the application effect of these materials in practice is limited by many factors, including the physical and chemical properties of the formation, the width of the cracks and the pressure environment. At the same time, due to the high cost of the plugging material itself, repeated replacement or multiple use of plugging slurry will also significantly increase the construction cost.

[0004] With the increasing complexity of downhole working conditions, how to more accurately simulate the multiphase flow behavior in the wellbore, especially the flow and flushing effect of drilling fluid in the annulus, has become an important research direction in the field of drilling science. At present, most wellbore simulation devices on the market have the limitation of being unable to accurately simulate actual construction conditions, especially the lack of effective detection methods for the flushing effect of the well wall and the stability of plugging particles in a dynamic environment, which leads to a large gap between experimental results and actual applications, and there is an urgent need to develop more advanced simulation devices.

[0005] Therefore, we propose a dynamic plugging simulation device for wellhead pressure holding. Summary of the invention

[0006] The present invention aims to solve the technical problems existing in the prior art in simulating wellhead dynamic pressure and plugging experimental devices, and provides a wellhead pressure holding dynamic plugging simulation device that can truly reproduce the complex dynamic pressure environment and fluid flow characteristics in the wellbore, providing experimental support for plugging material performance testing and process optimization.

[0007] In order to achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a dynamic plugging simulation device for wellhead pressure holding, including a simulated wellbore, a variable diameter rotating rod, a lifting system, a rotary drive device, a drilling fluid circulation system, a pressure monitoring system, a flow rate and shear rate detection device, a data acquisition and control system, and a core clamp system. The simulated wellbore is made of transparent visual material and is used to observe the flow characteristics of the fluid in the wellbore. The inner diameter of the wellbore is fixed to ensure the visualization of the fluid flow state during the experiment. The variable diameter rotating rod adopts a retractable structure with an adjustable diameter, which is connected to the rotary drive device to simulate different spacings between the well wall and the drill rod to meet the requirements under different experimental conditions. The lifting system is composed of an electric lift or a hydraulic lift device to control the lifting and lowering movement of the rotating rod and simulate the up and down movement of the drill bit during the drilling process. The rotary drive device includes a motor and a reduction box to drive the rotating rod to rotate, simulating the stirring effect generated by the rotation of the drill bit, and the rotation rate is adjustable to study its influence on the fluid flow. The drilling fluid circulation system is used to supply and circulate drilling fluid. It includes components such as pumps, pressure regulating valves, safety valves, ball valves, check valves and liquid storage tanks. It can adjust the flow rate and pressure to simulate the actual flow state of drilling fluid. The pressure monitoring system consists of a pressure sensor and a data acquisition device, which is used to monitor the pressure changes at the wellhead in real time to ensure accurate and stable pressure control during the experiment. The flow rate and shear rate of the drilling fluid in the annulus are measured in real time through ultrasonic flow meters, laser Doppler flow meters, and particle image velocimetry systems, and its flow law under different working conditions is analyzed. The data acquisition and control system consists of a computer (CRT), a data acquisition card (PLC) and a controller, which are used to collect experimental data, including flow rate, shear rate, rotation speed, temperature and pressure, and optimize the experimental process. The core holder system includes an end face filtration holder, a fracture core and a pressure sensor, which is used to simulate fracture plugging experiments and realize dynamic monitoring of pressure changes and filtration loss.

[0008] Preferably, the simulated wellbore is made of transparent visual material to facilitate real-time observation of the fluid characteristics inside the wellbore.

[0009] Preferably, the variable diameter rotating rod is linked to the rotation drive device to support dynamic adjustment of the diameter and rotation rate to adapt to a variety of experimental conditions.

[0010] Preferably, the drilling fluid circulation system is equipped with a pressure regulating valve, a safety valve and a check valve to achieve precise pressure regulation and backflow protection.

[0011] The lifting system is combined with the pressure monitoring system to monitor the pressure changes during the lifting process in real time and simulate the dynamic environment of drilling.

[0012] Preferably, the flow velocity and shear rate detection device is combined with laser Doppler technology to achieve high-precision flow parameter measurement.

[0013] Preferably, the core holder system works in conjunction with a pressure sensor to accurately monitor changes in fracture pressure and filtration loss.

[0014] The present invention provides a dynamic plugging simulation device for wellhead pressure holding. It has the following beneficial effects:

[0015] 1. This dynamic plugging simulation device for wellhead pressure holding can accurately reproduce the plugging phenomenon under wellhead pressure holding during drilling by simulating the dynamic environment and flow conditions in the wellbore. Through the real-time monitoring and adjustment function of the device, the flow characteristics of the drilling fluid in the annulus can be fully analyzed, and the influence of factors such as flow velocity and shear rate on the plugging effect can be studied, thereby providing a scientific basis and optimization plan for wellhead plugging operations in actual projects, and improving the success rate and safety of plugging operations.

[0016] 2. This dynamic plugging simulation device for wellhead pressure holding can systematically evaluate the performance of different plugging materials under complex working conditions, including key parameters such as plugging rate, filtration loss, and rheological properties of plugging materials. Through precise experimental design and data analysis, researchers can select the most suitable plugging materials according to different formation conditions, pressure environments, and flow states, optimize plugging solutions, significantly improve operating efficiency, and reduce costs.

[0017] 3. This dynamic plugging simulation device for wellhead pressure holding has a simple structure and operation interface, flexible experimental parameter setting and adjustment, user-friendly operation, and can effectively reduce the training cost of experimental personnel. Through a highly integrated data acquisition and control system, the experimental results can be monitored and optimized in real time, ensuring the stability and efficiency of the experimental process and reducing the risk of errors during operation.

[0018] 4. This dynamic plugging simulation device for wellhead pressure holding has good applicability and can be widely used in different types of drilling projects. By simulating a variety of variable working conditions such as downhole pressure, flow rate, temperature, etc., it can provide reliable experimental data support for plugging operations in the fields of oil, natural gas, groundwater, etc., especially under complex geological conditions, which can effectively improve the success rate and reliability of drilling operations and promote the progress and development of related technologies. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the implementation of the present invention or the technical solution in the prior art, the following briefly introduces the drawings required for the implementation or the description of the prior art. Obviously, the drawings in the following description are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0020] The structures, proportions, sizes, etc. illustrated in this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with the technology. They are not used to limit the conditions under which the present invention can be implemented, and therefore have no substantial technical significance. Any structural modification, change in proportion or adjustment in size shall still fall within the scope of the technical contents disclosed in the present invention without affecting the effects and purposes that can be achieved by the present invention.

[0021] Figure 1 The present invention is a schematic diagram of a dynamic plugging simulation device for wellhead pressure holding.

[0022] Legend:

[0023] 1. Simulated wellbore; 2. Variable diameter rotating rod; 3. Lifting system; 4. Rotary drive device; 5. Drilling fluid circulation system; 6. Pressure monitoring system; 7. Flow rate and shear rate detection device; 8. Data acquisition and control system; 9. Core holder system; 10. Electric lift; 11. Hydraulic lift; 12. Motor; 13. Gearbox; 14. Booster pump; 15. Safety valve; 16. Pressure regulating valve; 17. Ball valve; 18. Check valve; 19. Ultrasonic flowmeter; 20. Laser Doppler flowmeter 1. Particle image velocimetry system; 2. Computer (CRT); 2. Data acquisition card (PLC); 2. Controller; 2. End face filtration holder; 2. Fracture core; 2. Pressure sensor; 2. Gas cylinder; 2. Gas cylinder valve; 3. Liquid storage tank 1; 3. Pressure test instrument; 3. Pressure signal transmitter; 3. Displacement control valve; 3. Speed ​​controller; 3. Liquid storage tank 2; 3. Annular pressure pump; 401. Hoist control switch; 601. Speed ​​controller switch DETAILED DESCRIPTION

[0024] The technical scheme in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is only a part of the embodiment of the present invention, not all of the embodiments. Based on the embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the protection scope of the present invention.

[0025] Embodiment: A dynamic plugging simulation device for wellhead pressure holding, such as Figure 1 As shown, the present invention relates to a dynamic plugging simulation device for wellhead pressure holding, comprising a simulated wellbore 1, a variable diameter rotating rod 2, a lifting system 3, a rotary drive device 4, a drilling fluid circulation system 5, a pressure monitoring system 6, a flow rate and shear rate detection device 7, a data acquisition and control system 8 and a core clamp system 9.

[0026] The simulated wellbore 1 is made of organic glass and steel and is used to simulate the wellbore environment downhole. Its inner diameter is fixed and its outer wall is transparent, so the flow characteristics of the drilling fluid in the wellbore can be directly observed. The simulated wellbore is used to demonstrate the flow of drilling fluid in the annulus and its interaction with the plugging material in the experiment; the variable diameter rotating rod 2 adopts a retractable structure, which can simulate different wellbore sizes and the change of the spacing between the well wall and the drill rod by adjusting the diameter, so as to meet the requirements of various experimental conditions. The rotating rod is rotated by the rotating drive device 4, which further enhances the dynamic simulation ability of the experiment; the lifting system 3 is composed of an electric lift 10 and a hydraulic lifting device 11, which can control the lifting and lowering movement of the rotating rod or the drill bit. Its function is to simulate the dynamic process of the drill bit moving up and down during the drilling process, so as to analyze the flow, distribution and plugging efficiency of the plugging material in the wellbore; the rotating drive device 4 includes a motor 12, a reduction box 13, a speed control switch 601 and a hoist control switch 401. The motor drives the rotating rod to rotate at an adjustable speed, and the reduction box is used to accurately control the speed, so as to study the influence of different speeds on the flow characteristics in the annulus; the drilling fluid circulation system 5 includes a booster pump 14, a safety valve 15, a pressure regulating valve 16, a ball valve 17, a check valve 18 and a liquid storage tank 30. The booster pump is used to provide power to transport the drilling fluid to the wellbore, the pressure regulating valve adjusts the fluid pressure, the safety valve ensures the safety of the system protection device when overpressure occurs, and the check valve prevents the drilling fluid from flowing back. The liquid storage tank 30 is used to store drilling fluid for continuous operation of the experiment; the pressure monitoring system 6 is composed of a pressure sensor 27, a pressure test instrument 31 and a pressure signal transmitter 32. The system can monitor the pressure changes in the wellhead and the annulus in real time, and provide accurate pressure environment simulation data for the experiment; the flow rate and shear rate detection device 7 is combined with an ultrasonic flow meter 19, a laser Doppler flow meter 20 and a particle image velocimetry system 21. The device can measure the flow rate, shear rate and flow state of the drilling fluid in the annulus, support high-precision data acquisition, and ensure the reliability of the experimental results; the data acquisition and control system 8 is composed of a computer (CRT) 22, a data acquisition card (PLC) 23 and a controller 24, and is used for the acquisition, storage and analysis of experimental data. The system supports real-time monitoring of multiple parameters during the experiment, including displacement, pressure, flow rate and shear rate, and provides automatic control functions; the core clamp system 9 is composed of an end face filtration clamp 25, a fracture core 26, and an annular pressure pump 36 connecting the core clamp and the pressure sensor 27, which is used to simulate fracture formation conditions. The end face filtration clamp ensures the stability of the core during the experiment, the fracture core is used to analyze the permeability and plugging effect of the plugging slurry, the annular pressure pump 36 can apply external pressure to the core to simulate the confining pressure conditions of the real formation, and the pressure sensor monitors the surface and internal pressure changes of the core in real time.

[0027] Implementation Case 1

[0028] Small cracks and narrow annulus conditions, wellbore diameter: 30cm, drill pipe diameter: 6cm, annulus width: 12cm, core crack width: 1mm, plugging particle size: 0.33mm~0.5mm, speed range: 50~250rpm

[0029] Steps: Inject plugging particle drilling fluid and evenly distribute the particles near the crack mouth. The initial rotation speed is 50rpm. It is observed that the particles gradually accumulate and form a crack barrier. When the rotation speed is increased to 150rpm, particles begin to fall off. The rotation speed continues to rise to 200rpm, the plugging particles at the crack mouth are completely washed away, and subsequent particles enter the crack to achieve stable plugging. The critical flushing speed is about 180rpm. The subsequent particle replenishment has good stability.

[0030] Implementation Case 2

[0031] Medium crack width and wide annulus conditions: wellbore diameter: 30cm, drill pipe diameter: 7.5cm, annulus width: 11.25cm, core crack width: 2mm, plugging particle size: 0.66mm~1mm, rotation speed range: 50~300rpm.

[0032] Steps: Prepare the plugging granular drilling fluid and inject the liquid into the simulated wellbore at an initial speed of 100rpm. The particles begin to accumulate at the entrance of the fracture. The speed is gradually increased to 250rpm, and the crack sealing particles are gradually washed away. Subsequent particles accumulate along the fracture and eventually reach a stable plugging state. The plugging pressure remains stable after reaching the peak. The critical flushing speed is 240rpm, and the annulus width with the best plugging effect is about 11.25cm.

[0033] Implementation Case 3

[0034] Large crack conditions: wellbore diameter: 30cm, drill pipe diameter: 6cm, annulus width: 12cm, core crack width: 4mm, plugging particle size: 1.33mm~2mm, rotation speed range: 50~400rpm.

[0035] Steps: The initial speed is set to 50rpm, and the particles stay at the crack mouth in a dispersed state. After the speed increases to 200rpm, the particles form an incomplete bridge at the crack. When the speed reaches 350rpm, the front particles are washed away, and the subsequent particles continue to replenish to achieve a stable barrier, and the crack is filled with particles. Data recording: The critical flushing speed is 320rpm. The crack plugging integrity is good and the pressure isolation is significant.

[0036] Implementation Case 4

[0037] Medium cracks and small annulus conditions: wellbore diameter: 30cm, drill pipe diameter: 7cm, annulus width: 11.5cm, core crack width: 2mm, plugging particle size: 0.66mm~1mm, rotation speed range: 50~250rpm.

[0038] Steps: The initial rotation speed of the drill pipe is set at 100rpm. After the drilling fluid is injected, the plugging particles gradually form a barrier at the crack mouth. When the rotation speed is increased to 200rpm, the particles at the crack mouth are completely washed away, but the plugging material inside the crack continues to fill, forming a secondary barrier. The critical flushing speed is 190rpm. The crack is finally sealed firmly.

[0039] Implementation Case 5

[0040] Wide annulus and multiple fracture conditions: wellbore diameter: 30cm, drill pipe diameter: 6.5cm, annulus width: 11.75cm, core fracture width: 3mm, plugging particle size: 1mm~1.5mm, rotation speed range: 50~350rpm.

[0041] Steps: The initial speed is 75rpm, the drilling fluid flows in the cracks, and the particles gradually accumulate to form a barrier. When the speed is increased to 275rpm, the crack sealing particles are partially washed away, but do not interfere with the subsequent blocking particles. The critical flushing speed is 260rpm. In the case of multiple cracks, the particles are evenly distributed, and the cracks are completely blocked.

[0042] Implementation Case 6

[0043] Narrow annulus and large particle conditions Wellbore diameter: 30cm, drill pipe diameter: 6cm, annulus width: 12cm Core crack width: 3mm, plugging particle size: 1mm~1.5mm, speed range: 50~300rpm

[0044] Steps: The initial speed is set at 100rpm, and the particles gather near the cracks. Observe the particles gradually accumulate at the crack entrance. Increase to 250rpm, the sealing particles partially fall off, and the subsequent particles enter the cracks and accumulate stably. The critical scouring speed is 230rpm, and large particles are easy to form a stable barrier under narrow annular conditions.

[0045] Dynamic pressure difference adjustment at the wellbore inlet: the pressure pump 31 is separately arranged at the wellbore inlet and used in conjunction with the gas cylinder 28 to accurately adjust the dynamic pressure in the wellbore. The pressure regulating valve 16 is used to adjust the pressure change, and the ball valve 17 and the check valve 18 ensure the one-way flow of the experimental fluid and the rapid switching of the channel; real-time data monitoring and analysis: the data acquisition card (PLC) 23 is connected to various sensors to collect experimental data such as pressure, flow rate, and flushing speed. The computer (CRT) 22 runs the controller 24 to analyze the experimental data in real time and dynamically adjust the plugging experiment parameters; dynamic plugging experiment: the booster pump 14 transports the drilling fluid to the simulated wellbore 1, and combines the core clamp system to apply dynamic pressure to the fracture core 26 to simulate the plugging process of the plugging material in the fracture. The flow rate and shear rate detection device is used to analyze the fluid behavior and evaluate the plugging effect; waste liquid treatment and recovery: the waste liquid after the experiment is introduced into the liquid storage tank 2 37 through the displacement control valve 33 to avoid pollution to the experimental environment and facilitate post-experimental processing.

[0046] Working principle of the present invention:

[0047] During the experiment, the fractured core was first placed in the core holder system, and an annular pressure pump was used to apply annular pressure to it to simulate the formation pressure environment, so as to ensure that the state of the fractured core in the experiment was consistent with the actual underground conditions. The application of annular pressure can not only reproduce the stress environment in the formation, but also effectively avoid the change of fracture morphology caused by external forces, thereby improving the reliability and accuracy of the experimental results.

[0048] Subsequently, the drilling fluid circulation system is started, and the drilling fluid is injected into the simulated wellbore through a pump. The injection process is combined with a pressure regulating valve, a safety valve and a check valve to flexibly adjust the flow and pressure to simulate the flow characteristics of the drilling fluid under different wellhead pressure conditions. If a single cycle cannot complete the plugging, it can be switched to the secondary circulation experiment mode to further optimize the plugging effect of the plugging slurry by adjusting the fluid parameters. The simulated wellbore is made of transparent materials, and the flow characteristics of the drilling fluid can be observed in real time. Before the fluid enters the wellbore, the pressure regulating valve adjusts the initial pressure of the fluid to ensure that the pressure in the wellbore reaches the preset value. The system also starts the rotary drive device to drive the variable diameter rotating rod to rotate. By controlling the diameter change and rotation rate of the rotating rod, the spacing between different well diameters and drill pipes and their rotation stirring effect are simulated. This process can simulate the flow state of drilling fluid in the wellbore annulus and study the influence of rotation rate on fluid flow law and plugging effect.

[0049] The lifting system dynamically adjusts the up and down movement of the rotating rod to simulate the lifting process of the drill bit. The lifting movement is combined with the pressure monitoring system to realize real-time monitoring of the wellhead pressure, which is convenient for analyzing the fluid flow and plugging effect under dynamic conditions. During the circulation process, the flow velocity and shear rate detection device is started, and the flow velocity and shear rate of the drilling fluid in the annulus are measured by the laser Doppler velocimeter or particle image velocimetry system, providing high-precision flow data for analyzing flow characteristics.

[0050] During the experiment, a rotating drive device was used to drive a variable diameter rotating rod to rotate, simulating the stirring effect of the rotation of the downhole drill bit on the fluid, and the diameter of the rotating rod was adjusted to adapt to different annular gaps. The lifting system controlled the up and down movement of the rotating rod to simulate the dynamic lifting of the drill bit during drilling operations and study the plugging performance of the fluid in a dynamic pressure environment.

[0051] In order to monitor fluid parameters in real time, the flow rate and shear rate detection device combines ultrasonic flow meter or laser Doppler velocity measurement technology to accurately measure the drilling fluid flow rate and shear rate in the wellbore annulus to ensure the integrity and accuracy of the experimental data. The pressure monitoring system dynamically records the wellhead pressure and its changes through the pressure sensor and data acquisition device inside the wellbore. Combined with the automated analysis function of the data acquisition and control system, the experimental parameters such as temperature, rotation speed, flow rate and pressure can be monitored synchronously, and the experimental process can be optimized and controlled.

[0052] Through the transparent simulated wellbore material, the flow characteristics of the drilling fluid and the distribution and settlement state of the plugging slurry in the wellbore can be directly observed. During the experiment, the pressure, flow rate and speed conditions can be flexibly adjusted. The system supports multiple working condition simulations and data recording functions, providing scientific support for the performance research of plugging materials and the optimization of plugging processes.

[0053] Therefore, the above working principle framework is only an example and should not be understood as limiting the scope of protection of the present invention. Based on this framework, those skilled in the art can realize various optimizations and extended applications without departing from the spirit and scope of the present invention, all of which belong to the scope of protection of the present invention.

[0054] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0055] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0056] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0057] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0058] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0059] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A dynamic plugging simulation device for wellhead pressure holding, characterized in that: It includes a simulated wellbore, a variable diameter rotating rod, a lifting system, a rotary drive device, a drilling fluid circulation system, a pressure monitoring system, a flow rate and shear rate detection device, a data acquisition and control system, and a core clamp system; the simulated wellbore is used to simulate the environment inside the wellbore, is made of transparent visual materials, has a fixed inner diameter, and is used to observe the flow characteristics of the drilling fluid; the variable diameter rotating rod adopts a retractable structure with an adjustable diameter to simulate different spacings between the well wall and the drill rod; the lifting system is composed of an electric lift or a hydraulic lift device to control the lifting of the drill rod and simulate the up and down movement of the drill head; the rotary drive device includes a motor and a reduction box to drive the rotating rod to rotate and provide an adjustable stirring rate; the drilling fluid circulation The annular system is used to supply and circulate drilling fluid, and includes a pump, a valve, a pipeline and a fluid storage tank to control the flow rate and simulate the actual flow state; the pressure monitoring system includes a pressure sensor and a data acquisition device to monitor the wellhead pressure holding situation; the flow rate and shear rate detection device measures the flow rate and shear rate of the drilling fluid in the annulus through an ultrasonic flow meter, a laser Doppler flow meter, and a particle image velocimetry system; the data acquisition and control system is composed of a computer (CRT), a data acquisition card (PLC) and a controller, which are used to collect experimental data and control the experimental process; the core clamp system includes an end face filtration clamp, a fracture core and a pressure sensor, which is used to simulate the fracture plugging experiment.

2. A dynamic plugging simulation device for wellhead pressure holding according to claim 1, characterized in that: The simulated wellbore is made of transparent visual materials to ensure visualization of flow characteristics in the wellbore; the variable diameter rotating rod is connected to the rotary drive device to achieve dynamic adjustment of the diameter and rotation rate for simulation under different experimental conditions.

3. The dynamic plugging simulation device for wellhead pressure holding according to claim 1 is characterized in that: The drilling fluid circulation system includes a pressure regulating valve, a safety valve, a ball valve and a check valve; the pressure regulating valve is used to adjust the pressure of the injected fluid, the safety valve prevents pressure overload, the ball valve quickly opens or closes the fluid channel, and the check valve is used to prevent drilling fluid backflow.

4. The dynamic plugging simulation device for wellhead pressure holding according to claim 1 is characterized by: The lifting system is combined with a pressure monitoring system to monitor the pressure changes at the wellhead during the lifting process in real time, simulating the dynamic pressure environment during the drilling process.

5. The dynamic plugging simulation device for wellhead pressure holding according to claim 1 is characterized in that: The data acquisition and control system is used to monitor the displacement, flushing speed, rotation speed, temperature and pressure; the system supports the storage and real-time analysis of experimental data to optimize the plugging process parameters.

6. The dynamic plugging simulation device for wellhead pressure holding according to claim 1 is characterized by: The core holder system adopts an end face filtration holder, combined with a fracture core and a pressure sensor, to provide dynamic pressure and filtration amount monitoring functions.

7. The dynamic plugging simulation device for wellhead pressure holding according to claim 1 is characterized by: The flow velocity and shear rate detection device combines laser Doppler technology to provide high-precision flow velocity and shear rate measurement for analyzing the flow law of drilling fluid in the annulus.

8. The dynamic plugging simulation device for wellhead pressure holding according to claim 1 is characterized by: The rotary drive device and the speed controller are operated in conjunction with each other, and the influence of the speed on the flow characteristics of the drilling fluid annulus is studied by accurately controlling the speed.

9. The dynamic plugging simulation device for wellhead pressure holding according to claim 1 is characterized in that: The pressure monitoring system and the intelligent system work together to use the pressure regulating valve and the pressure pump to simulate the plugging experiment environment under different pressure and flow conditions.

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