Downhole pressure drop simulation experiment device

Abstract

The utility model discloses an underground pressure drop simulation experiment device which is characterized in that the output end of a variable-frequency asynchronous motor is connected to a power steering mechanism, the power steering mechanism is connected to a polish rod, and the end, away from the power steering mechanism, of the polish rod penetrates through a mounting platform to be connected to a screw pump; the sleeve is mounted at the bottom of the mounting platform, and the screw pump is arranged in the sleeve; the first sensor is mounted at the output end of the centrifugal pump; the second sensor penetrates through the outer wall of the sleeve, extends into the gap and is close to the backflow end of the slurry circulating box; the third sensor penetrates through the outer wall of the sleeve, extends into the gap and is close to the bottom of the screw pump, and the data acquisition instrument is electrically connected to the first sensor, the second sensor and the third sensor; and the computer data recording device is electrically connected to the data acquisition instrument. According to the application, the unique medium flow channel is constructed, and various sensors, the data acquisition instrument and the computer data recording device are integrated, so that comprehensive evaluation and optimization of the performance of the screw pump are realized.

Description

Technical Field

[0001] The present application relates to the field of offshore petroleum engineering technology, and in particular to a well depressurization simulation experimental device. Background Art

[0002] As drilling depths increase, most offshore oilfields often encounter narrow density window drilling fluid losses in the middle and late stages of development. This problem has seriously restricted safe and efficient downhole drilling. Therefore, to address the unfavorable conditions of high drilling fluid density, high circulating friction, and a narrow operating window in ultra-high temperature and high pressure narrow density window environments, controlling and monitoring downhole equivalent circulating density (ECD) and pressure has become a top priority.

[0003] Numerous researchers have investigated downhole pressure reduction tools, using simulation software to model the effectiveness of progressive cavity pumps in reducing downhole pressure and ECD under mud flow conditions. However, existing technologies are primarily limited to computer simulations and lack practical devices for realistically simulating downhole pressure. Furthermore, the lack of sensors to monitor downhole parameters such as annular pressure in real time hinders dynamic control of downhole pressure and optimization of the annular ECD. Utility Model Content

[0004] The embodiments of the present application provide a downhole pressure reduction simulation experimental device, which solves the technical problems in the prior art of lacking a practical device to simulate real downhole pressure and being unable to achieve dynamic control of downhole pressure and optimize the equivalent circulating density of the annulus.

[0005] The embodiment of the present application provides a well depressurization simulation experimental device, including a mounting platform, a power component, a centrifugal pump, a variable frequency asynchronous motor, a mud circulation box, a power steering mechanism, a polished rod, a screw pump, a sleeve, a data acquisition instrument, a first sensor, a second sensor, a third sensor and a computer data recording device; the power component, the centrifugal pump, the variable frequency asynchronous motor and the mud circulation box are all installed on the top of the mounting platform; the output end of the power component is connected to the centrifugal pump, the input end of the centrifugal pump is connected to the output end of the mud circulation box; the output end of the variable frequency asynchronous motor is connected to In the power steering mechanism, the power steering mechanism is connected to the polished rod, one end of the polished rod away from the power steering mechanism passes through the mounting platform and is connected to the screw pump, the axial direction of the polished rod is perpendicular to the axial direction of the variable frequency asynchronous motor, and the power steering mechanism is used to convert the rotational motion output by the variable frequency asynchronous motor into the rotational motion of the polished rod along the vertical direction; the sleeve is installed at the bottom of the mounting platform, the screw pump is arranged in the sleeve, the inner wall of the sleeve and the outer wall of the screw pump form a gap, and the sleeve and the screw pump are concentric axes; the The outer wall of the sleeve is provided with an inlet and an outlet, the height of the inlet is greater than the height of the outlet, the pipeline at the output end of the centrifugal pump passes through the mounting platform and is connected to the inlet, the inlet is connected to the input flow channel of the screw pump, and the pipeline at the return end of the mud circulation box passes through the mounting platform and is connected to the outlet; the pipeline at the return end of the mud circulation box and the pipeline at the output end of the centrifugal pump are respectively provided with a first stop valve and a second stop valve; the first sensor is installed at the output end of the centrifugal pump for measuring the medium pressure at the inlet; the second sensor passes through the sleeve The outer wall of the sleeve extends into the gap and is close to the return end of the mud circulation box, for measuring the medium pressure at the outlet; the third sensor passes through the outer wall of the sleeve, extends into the gap and is close to the bottom of the screw pump, for measuring the sleeve annulus pressure, and the data acquisition instrument is electrically connected to the first sensor, the second sensor and the third sensor; the computer data recording device is electrically connected to the data acquisition instrument, and the computer data recording device is configured to record the pressure data collected by the data acquisition instrument and convert the pressure data into a form representing the equivalent circulation density of the screw pump annulus.

[0006] In a possible implementation, the power steering mechanism includes a turbine and a worm; the output end of the variable frequency asynchronous motor is connected to the worm; the worm is engaged with the turbine, and the polished rod is connected to the turbine via a square clip.

[0007] In a possible implementation, the downhole pressure reduction simulation experimental device further includes an anchor; the anchor is sleeved on the middle portion of the outer wall of the screw pump.

[0008] In a possible implementation, the downhole pressure reduction simulation experimental device further includes a mechanical sealing sleeve; the mechanical sealing sleeve is mounted on a side of the anchor away from the screw pump.

[0009] In a possible implementation, the downhole pressure reduction simulation experimental device further includes a labyrinth sealing sleeve; the labyrinth sealing sleeve is mounted on a side of the anchor away from the screw pump.

[0010] In a possible implementation, the downhole pressure reduction simulation experimental device further includes a double universal joint rod; two ends of the double universal joint rod are respectively connected to an end of the polished rod away from the power steering mechanism and the rotor of the screw pump.

[0011] In a possible implementation, the downhole pressure reduction simulation experimental device further includes a support frame; two ends of the support frame are respectively connected to the top of the mounting platform and the pipeline at the return end of the mud circulation box.

[0012] One or more technical solutions provided in the embodiments of this application have at least the following technical effects:

[0013] The downhole pressure reduction simulation experimental device provided in the embodiment of the present application includes a mounting platform, a power component, a centrifugal pump, a variable frequency asynchronous motor, a mud circulation box, a power steering mechanism, a polished rod, a screw pump, a sleeve, a data acquisition instrument, a first sensor, a second sensor, a third sensor, and a computer data recording device. The present application simulates the circulation and pressure reduction process of the medium in the downhole by constructing a unique medium flow channel. Specifically, the pipeline at the output end of the centrifugal pump, the input flow channel from the inlet of the sleeve to the screw pump, and the flow channel from the top of the screw pump to the outlet together constitute the upper half of the medium circulation flow channel in the downhole; while the input flow channel and output flow channel of the screw pump constitute the lower half of the medium pressure reduction flow channel in the downhole. This design not only restores the real downhole environment, but also enables researchers to accurately evaluate the performance of the screw pump in the simulation experiment, especially its pressure reduction effect on the annulus. In the experiment, the first sensor, the second sensor, and the third sensor were installed to monitor the pressure changes of the mud at different locations in real time. These sensors provide key data for analyzing the working status of the screw pump, optimizing the design, and improving the pressure reduction effect. In addition, the controllability of the experiment enables researchers to adjust parameters such as the power components, the speed of the variable-frequency asynchronous motor, and the viscosity and density of the mud, so as to observe and record the pressure reduction effect of the screw pump under different conditions. The power steering mechanism of this application converts the lateral output power of the variable-frequency asynchronous motor into rotational power in the vertical direction, effectively reducing the influence of gravity on the clearance between the rotor and stator of the screw pump, and further improving the accuracy and reliability of the experiment. Therefore, the downhole pressure reduction simulation experimental device realizes a comprehensive evaluation and optimization of the performance of the screw pump by constructing a unique medium flow channel, integrating multiple sensors, data acquisition instruments and computer data recording devices. This device not only improves the efficiency and accuracy of the experiment, but also provides a scientific basis for equipment selection and parameter setting in actual drilling operations. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following is a brief introduction to the drawings required for use in the description of the embodiments of the present application. Obviously, the drawings described below are some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0015] Figure 1 A schematic diagram of the structure of a simulation device provided in an embodiment of the present application;

[0016] Figure 2 A cross-sectional view of a simulation device provided in an embodiment of the present application;

[0017] Figure 3 A schematic diagram of the flow path of the simulation device provided in an embodiment of the present application;

[0018] Figure 4 A schematic diagram of the structure of a labyrinth sealing sleeve provided in an embodiment of the present application;

[0019] Figure 5 An exploded view of a labyrinth seal sleeve provided in an embodiment of the present application;

[0020] Figure 6 A schematic structural diagram of a mechanical sealing sleeve provided in an embodiment of the present application;

[0021] Figure 7 This is an exploded view of the mechanical sealing sleeve provided in an embodiment of the present application.

[0022] Icons: 1-installation platform; 2-power parts; 3-centrifugal pump; 4-variable frequency asynchronous motor; 5-mud circulation box; 6-power steering mechanism; 7-light rod; 8-screw pump; 9-sleeve; 91-inlet; 92-outlet; 10-data acquisition instrument; 11-first sensor; 12-second sensor; 13-third sensor; 14-first stop valve; 15-second stop valve; 16-computer data recording device; 17-anchor; 18-labyrinth sealing sleeve; 19-double universal joint rod; 20-square clip; 21-mechanical sealing sleeve; 22-support frame. DETAILED DESCRIPTION

[0023] The following will be combined with the accompanying drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are part of the embodiments of this application, not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of this application.

[0024] In the description of the embodiments of the present application, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside" 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 embodiments of the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limitations on the present application. The terms "first", "second" and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance. In addition, the terms "installed", "connected" and "connected" 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 a mechanical connection or an electrical connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be a communication between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0025] The present application embodiment provides a well depressurization simulation experimental device, such as Figures 1 to 7 As shown in Figure 1, the downhole pressure drop simulation experimental device includes a mounting platform 1, a power unit 2, a centrifugal pump 3, a variable-frequency asynchronous motor 4, a mud circulation box 5, a power steering mechanism 6, a polished rod 7, a screw pump 8, a sleeve 9, a data acquisition device 10, a first sensor 11, a second sensor 12, a third sensor 13, and a computer data recording device 16. The power unit 2, centrifugal pump 3, variable-frequency asynchronous motor 4, and mud circulation box 5 are all mounted on top of the mounting platform 1. The output end of the power unit 2 is connected to the centrifugal pump 3, and the input end of the centrifugal pump 3 is connected to the output end of the mud circulation box 5. The output end of the variable-frequency asynchronous motor 4 is connected to the power steering mechanism 6, which is connected to the polished rod 7. The end of the polished rod 7 away from the power steering mechanism 6 passes through the mounting platform 1 and connects to the screw pump 8. The axial direction of the polished rod 7 is perpendicular to the axial direction of the variable-frequency asynchronous motor 4. The power steering mechanism 6 is used to convert the rotational motion output by the variable-frequency asynchronous motor 4 into vertical rotational motion of the polished rod 7. A sleeve 9 is mounted at the bottom of the mounting platform 1. The screw pump 8 is housed within the sleeve 9. A gap is formed between the inner wall of the sleeve 9 and the outer wall of the screw pump 8, and the sleeve 9 and screw pump 8 are concentric. An inlet 91 and an outlet 92 are located on the outer wall of the sleeve 9. The inlet 91 is higher than the outlet 92. The pipe from the output of the centrifugal pump 3 passes through the mounting platform 1 and connects to the inlet 91. Inlet 91 connects to the input channel of the screw pump 8. The pipe from the return end of the mud circulation tank 5 passes through the mounting platform 1 and connects to the outlet 92. The return end pipe of the mud circulation tank 5 and the pipe from the output end of the centrifugal pump 3 are respectively equipped with a first shutoff valve 14 and a second shutoff valve 15. A first sensor 11 is mounted at the output end of the centrifugal pump 3 to measure the medium pressure at the inlet 91. A second sensor 12 passes through the outer wall of the sleeve 9, extends into the gap, and is located near the return end of the mud circulation tank 5 to measure the medium pressure at the outlet 92. A third sensor 13 extends through the outer wall of the sleeve 9, into the gap, and near the bottom of the screw pump 8. It is used to measure the annular pressure of the sleeve 9. The data acquisition device 10 is electrically connected to the first sensor 11, the second sensor 12, and the third sensor 13. A computer data recording device 16 is electrically connected to the data acquisition device 10 and is configured to record the pressure data collected by the data acquisition device 10 and convert the pressure data into a form representing the equivalent circulating density of the annular space of the screw pump 8. The power component 2 is a three-phase asynchronous motor. Three-phase asynchronous motors have high energy conversion efficiency.

[0026] It should be noted that this application simulates the circulation and pressure reduction process of the medium in the well by constructing a unique medium flow channel. Specifically, the pipeline at the output end of the centrifugal pump 3, the inlet 91 of the sleeve 9 to the input flow channel of the screw pump 8, and the flow channel from the top of the screw pump 8 to the outlet 92 together constitute the upper half of the medium circulation flow channel in the well; while the input and output flow channels of the screw pump 8 constitute the lower half of the medium pressure reduction flow channel in the well. This design not only reproduces the real downhole environment, but also enables researchers to accurately evaluate the performance of the screw pump 8 in the simulation experiment, especially its pressure reduction effect on the annulus. During the experiment, a first sensor 11, a second sensor 12, and a third sensor 13 were installed to monitor the pressure changes of the mud at different locations in real time. These sensors provide key data for analyzing the working status of the screw pump 8, optimizing its design, and improving the pressure reduction effect. In addition, the controllable nature of the experiment enables researchers to adjust the speed of the power unit 2 and the variable frequency asynchronous motor 4, as well as parameters such as the viscosity and density of the mud, thereby observing and recording the pressure reduction effect of the screw pump 8 under different conditions. The power steering mechanism 6 of this application converts the lateral output power of the variable-frequency asynchronous motor 4 into vertical rotational power, effectively reducing the effect of gravity on the clearance between the rotor and stator of the screw pump 8, further improving the accuracy and reliability of the experiment. Therefore, by constructing a unique medium flow channel and integrating multiple sensors, a data acquisition device 10, and a computer data recording device 16, this downhole pressure drop simulation experimental device achieves a comprehensive evaluation and optimization of the performance of the screw pump 8. This device not only improves experimental efficiency and accuracy but also provides a scientific basis for equipment selection and parameter setting in actual drilling operations.

[0027] In actual operation, the simulation experiment method of downhole pressure reduction and detection uses a downhole pressure reduction simulation experiment device to simulate the downhole working environment. The simulation experiment method includes:

[0028] S1: inject mud into the mud circulation box 5, start the power part 2 to drive the centrifugal pump 3 to operate, the input end of the centrifugal pump 3 extracts the mud medium from the mud circulation box 5, and pressurizes the mud and transports it to the screw pump 8. At the same time, the output speed of the variable frequency asynchronous motor 4 is controlled, and the polished rod 7 is driven to rotate through the power steering mechanism 6. At this time, the first stop valve 14 and the second stop valve 15 are appropriately opened to allow the mud to flow through the pipe at the output end of the centrifugal pump 3, the sleeve 9 and the pipe at the return end of the mud circulation box 5, so as to achieve the purpose of wetting and cleaning the simulation device;

[0029] S2: The pressure changes of the first sensor 11, the second sensor 12 and the third sensor 13 are collected by the data acquisition instrument 10. The computer data recording device 16 records the pressure data collected by the data acquisition instrument 10 and converts the pressure data into a form representing the equivalent circulating density of the annulus of the screw pump 8. This conversion process will continue until the mud fully fills the inside of the sleeve 9 and a small amount of mud returns to the mud circulation box 5.

[0030] It should be noted that the pressure data conversion formula is:

[0031]

[0032] Among them, ρ ECD is the equivalent circulation density; ρ mud is the downhole static density, that is, the density of the drilling fluid; ΔP is the friction pressure drop generated during the flow of the mud; h is the wellbore depth, that is, the height of the casing 9.

[0033] In deepwater drilling operations, equivalent circulating density (ECD) is a crucial parameter, which is directly related to the stability of the wellbore and the smoothness of mud circulation. If the ECD is too high, it may lead to serious problems such as wellbore rupture and mud loss, which have caused shutdowns and high costs to many drilling projects. In addition, high ECD may also cause the drill to get stuck in the well, seriously hindering the progress of drilling operations, further increasing operating costs, and adversely affecting the overall stability of the wellbore. In order to solve the above problems, the present application realizes real-time monitoring of the annulus pressure data of the screw pump 8 through the close cooperation of the data acquisition instrument 10 and the computer data recording device 16. The system can provide real-time feedback on changes in equivalent circulating density, allowing researchers to promptly detect abnormal conditions in the mud circulation, such as abnormal increases or decreases in pressure. By precisely controlling ECD, it can be ensured that the circulation state of the drilling fluid in the wellbore meets the design requirements, thereby reducing the probability of accidents, reducing downtime and costs, and improving the economic benefits of the overall drilling operation.

[0034] S3: Fully open the first stop valve 14 and the second stop valve 15, and detect the pressure changes of the first sensor 11, the second sensor 12, and the third sensor 13 again, while adjusting the speed of the variable frequency asynchronous motor 4 until the pressures displayed by the first sensor 11, the second sensor 12, and the third sensor 13 are stable. Then, record the pressure changes of the first sensor 11, the second sensor 12, and the third sensor 13 to evaluate the pressure reduction effect of the screw pump 8 on the annulus;

[0035] S4: Simulating different speeds of the power component 2 and the variable frequency asynchronous motor 4 to observe and record the pressure reduction effect of the screw pump 8 on the annulus under different conditions, and simultaneously record the pressure changes of the first sensor 11, the second sensor 12 and the third sensor 13;

[0036] S5: Close the power component 2, the variable frequency asynchronous motor 4, the first stop valve 14 and the second stop valve 15, add new mud liquid containing solid particles into the mud circulation box 5, simulate the annular space pressure reduction effect of the screw pump 8 under different viscosities and densities, and repeat steps S1-S4.

[0037] Specifically, by simulating mud fluids of different viscosities and densities, the annular pressure reduction performance of the screw pump 8 under different working conditions can be comprehensively evaluated, which helps to understand the adaptability of the screw pump 8 under different media conditions and provide a scientific basis for mud selection in actual drilling operations.

[0038] In the embodiment of the present application, the power steering mechanism 6 includes a turbine and a worm. The output end of the variable frequency asynchronous motor 4 is connected to the worm. The worm is engaged with the turbine, and the polished rod 7 is connected to the turbine via a square clip 20.

[0039] It should be noted that the high-speed rotation of the variable-frequency asynchronous motor 4 can be effectively converted into a low-speed, high-torque output of the turbine, which is crucial for the screw pump 8 because it requires sufficient torque to overcome various resistances underground and ensure the smooth transportation of the mud. In addition, the worm gear has a self-locking characteristic, that is, when the worm stops rotating, the turbine cannot reverse on its own. This characteristic is particularly important when the screw pump 8 is shut down because it can prevent the mud from reversing due to backflow. Therefore, the present application ensures the stability and reliability of the screw pump 8 during underground operation through the high reduction ratio and self-locking characteristics of the worm gear. At the same time, the worm gear enables the screw pump 8 to output a larger torque, thereby improving its adaptability in complex well conditions and ensuring the continuous and efficient transportation of mud.

[0040] In the embodiment of the present application, the downhole pressure reduction simulation experimental device further includes an anchor 17. The anchor 17 is sleeved on the middle part of the outer wall of the screw pump 8.

[0041] In the embodiment of the present application, the downhole pressure reduction simulation experimental device further includes a mechanical sealing sleeve 21. The mechanical sealing sleeve 21 is sleeved on the side of the anchor 17 away from the screw pump 8.

[0042] In the embodiment of the present application, the downhole pressure reduction simulation experimental device further includes a labyrinth seal sleeve 18. The labyrinth seal sleeve 18 is sleeved on the side of the anchor 17 away from the screw pump 8.

[0043] In the embodiment of the present application, after S5, the following steps are further included:

[0044] S6: Close the power component 2, the variable frequency asynchronous motor 4, the first stop valve 14 and the second stop valve 15, use the mechanical sealing sleeve 21 or the labyrinth sealing sleeve 18 to simulate the annular space pressure reduction effect of the screw pump 8 under different sealing conditions, and repeat steps S1-S5.

[0045] It should be noted that this application uses a mechanical seal sleeve 21 to simulate a fully sealed condition. The mechanical seal sleeve 21 is a high-precision sealing device that uses a tiny gap between two relatively moving sealing surfaces (usually a combination of metal and elastic material) to prevent fluid leakage. This sealing method can provide extremely high sealing performance, ensuring that the annulus area of ​​the screw pump 8 is completely isolated from the external environment.

[0046] This application uses a labyrinth seal 18 to simulate a semi-sealed condition. Based on the principles of fluid dynamics, the labyrinth seal 18 slows and restricts fluid flow through a complex series of channels and obstacles. These channels typically have varying cross-sectional shapes and sizes, creating multiple throttling and diffusion effects, thereby increasing resistance to fluid flow. While the labyrinth seal 18 cannot completely prevent fluid leakage, it can significantly reduce leakage. This semi-sealed condition allows a certain amount of fluid to pass through, but not enough to significantly impact the annular pressure reduction effect.

[0047] The outer wall of anchor 17 lacks any additional sealing devices and, therefore, cannot effectively prevent fluid from leaking from the annular space into the external environment, effectively simulating an extreme case of seal failure. Due to seal failure, a large amount of fluid will leak from the annular space into the external environment, significantly reducing the annular pressure reduction effect. Therefore, by varying the seal configuration to simulate different sealing conditions, the embodiments of the present application can comprehensively evaluate the annular pressure reduction effect of screw pump 8 under different conditions. This helps optimize the pump's design and operating parameters, improving its performance and reliability.

[0048] In the embodiment of the present application, the downhole pressure reduction simulation experimental device further comprises a double universal joint rod 19. The two ends of the double universal joint rod 19 are respectively connected to the end of the polished rod 7 away from the power steering mechanism 6 and the rotor of the screw pump 8.

[0049] Specifically, the double universal joint rod 19 has good buffering and shock absorbing performance, so it can effectively reduce the vibration and noise generated by the screw pump 8 during operation.

[0050] In the embodiment of the present application, the downhole pressure reduction simulation experimental device further includes a support frame 22. Both ends of the support frame 22 are connected to the top of the installation platform 1 and the pipeline at the return end of the mud circulation box 5 respectively.

[0051] It should be noted that the support frame 22 enhances the structural stability of the downhole pressure reduction simulation experimental device to prevent shaking or collapse under high pressure and high flow experimental conditions.

[0052] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other. Each embodiment focuses on the differences from other embodiments.

[0053] The above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit the present application. Although the present application has been described in detail with reference to the aforementioned embodiments, a person of ordinary skill in the art should understand that the technical solutions described in the aforementioned embodiments can still be modified, or some or all of the technical features therein can be replaced by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the present application.

Claims

1. A well depressurization simulation experimental device, characterized in that: The invention comprises a mounting platform (1), a power part (2), a centrifugal pump (3), a variable frequency asynchronous motor (4), a mud circulation box (5), a power steering mechanism (6), a polished rod (7), a screw pump (8), a sleeve (9), a data acquisition instrument (10), a first sensor (11), a second sensor (12), a third sensor (13) and a computer data recording device (16); The power component (2), the centrifugal pump (3), the variable frequency asynchronous motor (4), and the mud circulation box (5) are all installed on the top of the installation platform (1); The output end of the power member (2) is connected to the centrifugal pump (3), and the input end of the centrifugal pump (3) is connected to the output end of the mud circulation box (5); The output end of the variable frequency asynchronous motor (4) is connected to the power steering mechanism (6), the power steering mechanism (6) is connected to the polished rod (7), one end of the polished rod (7) away from the power steering mechanism (6) passes through the mounting platform (1) and is connected to the screw pump (8), the axial direction of the polished rod (7) is perpendicular to the axial direction of the variable frequency asynchronous motor (4), and the power steering mechanism (6) is used to convert the rotational motion output by the variable frequency asynchronous motor (4) into the rotational motion of the polished rod (7) along the vertical direction; The sleeve (9) is installed at the bottom of the installation platform (1), the screw pump (8) is arranged in the sleeve (9), the inner wall of the sleeve (9) and the outer wall of the screw pump (8) form a gap, and the sleeve (9) and the screw pump (8) are concentric axes; The outer wall of the sleeve (9) is provided with an inlet (91) and an outlet (92), the height of the inlet (91) is greater than the height of the outlet (92), the pipeline at the output end of the centrifugal pump (3) passes through the mounting platform (1) and is in communication with the inlet (91), the inlet (91) is in communication with the input flow channel of the screw pump (8), and the pipeline at the return end of the mud circulation box (5) passes through the mounting platform (1) and is in communication with the outlet (92); The pipeline at the return end of the mud circulation box (5) and the pipeline at the output end of the centrifugal pump (3) are respectively provided with a first stop valve (14) and a second stop valve (15); The first sensor (11) is installed at the output end of the centrifugal pump (3) and is used to measure the medium pressure at the inlet (91); the second sensor (12) passes through the outer wall of the sleeve (9), extends into the gap, and is close to the return end of the mud circulation box (5), and is used to measure the medium pressure at the outlet (92); the third sensor (13) passes through the outer wall of the sleeve (9), extends into the gap, and is close to the bottom of the screw pump (8), and is used to measure the annular space pressure of the sleeve (9). The data acquisition instrument (10) is electrically connected to the first sensor (11), the second sensor (12) and the third sensor (13); The computer data recording device (16) is electrically connected to the data acquisition instrument (10), and the computer data recording device (16) is configured to record the pressure data collected by the data acquisition instrument (10) and convert the pressure data into a form representing the equivalent circulating density of the annulus of the screw pump (8).

2. The well depressurization simulation experimental device according to claim 1, characterized in that: The power steering mechanism (6) includes a turbine and a worm; The output end of the variable frequency asynchronous motor (4) is connected to the worm; The worm is engaged with the turbine, and the polished rod (7) is connected to the turbine via a square clip (20).

3. The downhole pressure reduction simulation experimental device according to claim 1, characterized in that: Also included is an anchor (17); The anchor (17) is sleeved on the middle part of the outer wall of the screw pump (8).

4. The well depressurization simulation experimental device according to claim 3, characterized in that: Also includes a mechanical sealing sleeve (21); The mechanical sealing sleeve (21) is sleeved on a side of the anchor (17) away from the screw pump (8).

5. The well depressurization simulation experimental device according to claim 3, characterized in that: Also includes a labyrinth seal sleeve (18); The labyrinth sealing sleeve (18) is sleeved on a side of the anchor (17) away from the screw pump (8).

6. The downhole pressure reduction simulation experimental device according to claim 1, characterized in that: Also included is a double universal joint rod (19); The two ends of the double universal joint rod (19) are respectively connected to one end of the polished rod (7) away from the power steering mechanism (6) and the rotor of the screw pump (8).

7. The downhole pressure reduction simulation experimental device according to claim 1, characterized in that: Also includes a support frame (22); The two ends of the support frame (22) are respectively connected to the top of the installation platform (1) and the pipeline at the return end of the mud circulation box (5).

Images