Experimental equipment and experimental method for simulating generation of natural gas hydrate

Abstract

The invention relates to the technical field of permeability detection, in particular to experimental equipment and an experimental method for simulating generation of natural gas hydrate, and aims to solve the problem that conventional experimental equipment is difficult to detect the permeability of sediments on line. The device comprises an experimental container, a first closing mechanism is arranged in the experimental container, a second closing mechanism is arranged at the bottom of the experimental container, the experimental container comprises an experimental cylinder, a cutting ring is placed in the experimental cylinder, the first closing mechanism comprises an upper permeable stone, the second closing mechanism comprises a first bottom plate and a second bottom plate, and a lower permeable stone is placed on the upper portion of the second bottom plate; the experimental method comprises the following steps: emptying liquid in the experimental cylinder, controlling the upper permeable stone and the lower permeable stone to block two ports of the cutting ring, and carrying out permeability test on a sample in the cutting ring; the device can detect the permeability rate of the sample without taking the cutting ring and the sample in the cutting ring out of the experiment cylinder, and the experiment steps are simplified.

Description

Technical Field

[0001] The present invention relates to the technical field of permeability detection, in particular to an experimental device and an experimental method for simulating the formation of natural gas hydrates. Background Art

[0002] In the field of marine engineering equipment manufacturing and deep-sea oil drilling equipment manufacturing, it is crucial to study the performance of related equipment in complex marine environments. In particular, permeability testing in simulated marine sediment environments plays a key role in evaluating the stability and reliability of the interaction between equipment and sediments.

[0003] The manufacturing of offshore engineering equipment, such as jack-up workover platforms and platform lifting and locking devices, requires in-depth research into their interactions with seafloor sediments. For example, the penetration depth and stability of the platform legs are closely related to the sediment's permeability. This permeability influences the mechanical properties of the sediment, which in turn affects the platform's load-bearing capacity and stability. However, conventional testing methods present numerous challenges.

[0004] When testing the permeability of simulated seabed sediment samples using traditional experimental equipment and methods, it is often necessary to remove the cutter ring containing the sample from the simulation experimental container and then transfer it to a specialized penetration detection device for testing. This method makes it difficult to achieve online testing. The operation of this process is very cumbersome, and in the process of transferring the cutter ring and the sample, the sample structure is easily damaged due to the particularity of the marine environment simulation device and the complexity of the operation. Once the sample structure is damaged, the test results will be biased and unable to accurately reflect the actual changes in the seepage characteristics of the seabed sediments under different working conditions during the actual operation of the marine engineering equipment. This has brought great troubles to the design, safety assessment and subsequent maintenance of marine engineering equipment.

[0005] The manufacturing of deep-sea oil drilling equipment, such as subsea Christmas trees, blowout preventers, and subsea oil and gas production equipment, faces similar challenges. Installed on the seafloor, these devices interact with the surrounding sediments, and the permeability of these sediments impacts the equipment's stability, sealing, and long-term operational reliability. However, the limitations of traditional testing methods make it difficult to obtain accurate sediment permeability data, hindering equipment design optimization and performance improvement. Summary of the Invention

[0006] The present invention provides an experimental device and an experimental method for simulating the formation of natural gas hydrates, so as to solve the problem that traditional experimental equipment is difficult to detect sediment permeability online.

[0007] In order to alleviate the above technical problems, the technical solution provided by the present invention is:

[0008] An experimental device for simulating the formation of natural gas hydrates includes an experimental container, a first closing mechanism is provided in the experimental container, and a second closing mechanism is provided at the bottom. The experimental container includes an experimental cylinder, a ring knife is placed in the experimental cylinder, the first closing mechanism includes an upper permeable stone, the second closing mechanism includes a first bottom plate and a second bottom plate, a lower permeable stone is placed on the upper part of the second bottom plate, the first bottom plate and the second bottom plate can revolve around the midpoint of the line connecting the centers of the first and second bottom plates, so that the first bottom plate or the second bottom plate can block the experimental cylinder, when the upper permeable stone moves upward and the first bottom plate blocks the bottom of the experimental cylinder, the experimental cylinder is in an experimental state, and when the upper permeable stone moves downward and the second bottom plate blocks the bottom of the experimental cylinder, the experimental cylinder is in a permeability detection state.

[0009] Furthermore, the first closing mechanism also includes a accommodating cavity fixedly connected to the experimental cylinder, and the upper permeable stone can enter / move out of the accommodating cavity. A semicircular ring is fixedly connected to the edge of the upper permeable stone. After the upper permeable stone enters the semicircular ring, the semicircular ring can block the opening of the accommodating cavity.

[0010] Furthermore, both ends of the semicircular ring are fixedly connected to a rotating shaft, and a gear is fixedly connected to the rotating shaft. The inner wall of the experimental cylinder is provided with two sliding grooves for the two rotating shafts to slide, and a side wall in the middle of the sliding groove is provided with teeth that cooperate with the gear. When the rotating shaft moves downward so that the gear engages with the teeth, the upper permeable stone is separated from the accommodating cavity.

[0011] Furthermore, a notch is provided on the rotating shaft, and a convex strip is provided in the slide groove on the opposite side of the tooth. When the rotating shaft moves downward and the tooth is at the lower part, the upper permeable stone flips ninety degrees, and the notch is engaged with the convex strip, so that the upper permeable stone moves downward in a horizontal state to block the upper port of the ring knife.

[0012] Furthermore, a cylinder is fixedly connected to the top of the experimental tube, and an output end of the cylinder is rotatably connected to the rotating shaft.

[0013] Furthermore, the second closing mechanism also includes a connecting block, the first bottom plate and the second bottom plate are symmetrically connected to both sides of the connecting block, and a threaded rod is threadedly connected to the middle part of the connecting block, and the threaded rod can drive the connecting block to rotate and move axially. When the threaded rod drives the connecting block to rotate, the first bottom plate or the second bottom plate can move to the bottom of the experimental cylinder, and when the threaded rod drives the connecting block to move axially, the first bottom plate and the second bottom plate can move upward, thereby blocking the bottom of the experimental cylinder.

[0014] Furthermore, the experimental container also includes a mounting seat, the experimental cylinder is fixedly connected to the mounting seat, and two hydraulic rods are symmetrically fixedly connected to the mounting seat on both sides of the experimental cylinder, and the output ends of the two hydraulic rods are fixedly connected to limit blocks. After the two limit blocks move upward, the threaded rod can drive the connecting block to rotate, and when the first bottom plate or the second bottom plate moves to the lower part of the experimental cylinder, the limit block moves downward to abut against the side wall of the first bottom plate or the second bottom plate, so that the threaded rod can drive the connecting block to move axially.

[0015] Furthermore, the first closing mechanism also includes a water storage container, the bottom of the water storage container is connected to a drain pipe, the drain pipe is connected to a vertical pipe, the vertical pipe is connected to the upper permeable stone, the vertical pipe is connected to a pressure measuring tube, and a connecting pipe is connected between the vertical pipe and the drain pipe.

[0016] Furthermore, a water outlet pipe is connected to the second bottom plate, and the water outlet pipe is connected to the lower permeable stone.

[0017] An experimental method for simulating natural gas hydrate formation, applied to an experimental device for simulating natural gas hydrate formation, comprises the following steps:

[0018] When measuring permeability, the liquid in the test cylinder is emptied, and the cylinder is controlled to extend. The cylinder drives the semicircular ring to move the upper permeable stone downward out of the accommodation chamber. When the gear is engaged with the teeth, the upper permeable stone is separated from the accommodation chamber. The cylinder continues to extend, and the gear rolls on the teeth, causing the upper permeable stone to flip to a horizontal state. At the same time, the convex strip is engaged with the notch. The cylinder continues to extend, causing the upper permeable stone to move downward in a horizontal state until the upper permeable stone covers the upper end of the ring cutter.

[0019] Control the hydraulic rod to extend so that the two limit blocks abut against the side walls of the first bottom plate, control the threaded rod to reverse, so that the connecting block drives the first bottom plate and the second bottom plate to move downward synchronously, after the first bottom plate is separated from the experimental cylinder, control the hydraulic rod to shorten, and the threaded rod continues to rotate 180 degrees, so that the second bottom plate moves to the lower part of the experimental cylinder, control the hydraulic rod to extend so that the two limit blocks abut against the side walls of the second bottom plate, control the threaded rod to rotate forward, so that the connecting block drives the first bottom plate and the second bottom plate to move upward synchronously, and wait for the lower permeable stone to block the lower port of the ring knife so that both ports of the ring knife are closed;

[0020] Release the water in the water storage container and perform a permeability test on the sample in the ring cutter.

[0021] The beneficial effects of the present invention are analyzed as follows:

[0022] An experimental device for simulating the formation of natural gas hydrates comprises an experimental container, wherein a first closing mechanism is arranged in the experimental container and a second closing mechanism is arranged at the bottom. The experimental container comprises an experimental cylinder, wherein a ring knife is placed in the experimental cylinder, the first closing mechanism comprises an upper permeable stone, the second closing mechanism comprises a first bottom plate and a second bottom plate, a lower permeable stone is placed on the upper part of the second bottom plate, the first bottom plate and the second bottom plate can revolve around the midpoint of the line connecting the centers thereof, so that the first bottom plate or the second bottom plate can block the experimental cylinder, and when the upper permeable stone moves upward and the first bottom plate blocks the bottom of the experimental cylinder, the experimental cylinder is in an experimental state, and when the upper permeable stone moves downward and the second bottom plate blocks the bottom of the experimental cylinder, the experimental cylinder is in a permeability detection state.

[0023] When testing the permeability of the sample in the ring knife, if there is liquid in the experimental cylinder, the liquid will be discharged through the discharge pipe at the bottom of the first bottom plate, the upper permeable stone will be controlled to move down to block the upper port of the ring knife, and then the first bottom plate will be controlled to move out of the bottom of the experimental cylinder, so that the second bottom plate is moved to the bottom of the experimental cylinder, and the lower permeable stone will block the lower port of the ring knife. At this time, water will be passed into the upper permeable stone, and the water will penetrate the upper permeable stone and the sample and then be discharged through the lower permeable stone, which is to test the permeability of the sample. By setting the upper permeable stone in the experimental cylinder and moving the lower permeable stone to the bottom of the experimental cylinder, the permeability of the sample can be tested without taking the ring knife and the sample inside it out of the experimental cylinder, thereby simplifying the experimental steps. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in related technologies, the following briefly introduces the drawings required for use in the specific embodiments or related technical descriptions. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0025] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0026] Figure 2 is a cross-sectional view of the mounting base of the present invention;

[0027] Figure 3 is a cross-sectional view of the experimental tube of the present invention;

[0028] Figure 4 For the present invention Figure 3 Schematic diagram of the structure of part A;

[0029] Figure 5 This is a schematic structural diagram of the upper permeable stone of the present invention;

[0030] Figure 6 is a structural schematic diagram of the second closing mechanism of the present invention;

[0031] Figure 7 It is a structural schematic diagram of the threaded rod of the present invention.

[0032] icon:

[0033] 100, experimental container; 110, mounting base; 120, experimental tube; 121, chute; 122, teeth; 123, ridges; 130, ring cutter; 200, first closing mechanism; 210, accommodating chamber; 220, cylinder; 230, semicircular ring; 240, rotating shaft; 241, gear; 242, notch; 250, upper permeable stone; 260, vertical pipe; 261, connecting pipe; 270, drain pipe; 271, measuring Pressure pipe; 272, scale; 280, water storage container; 290, guide wheel; 291, pull rope; 292, counterweight; 300, second closing mechanism; 310, connecting block; 320, first bottom plate; 321, filter pressure plate; 330, second bottom plate; 331, lower permeable stone; 332, placement plate; 333, water outlet pipe; 340, motor; 341, threaded rod; 350, hydraulic rod; 360, limit block. DETAILED DESCRIPTION

[0034] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0035] In the description of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0036] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0037] Examples, such as Figure 1-Figure 7 As shown, an experimental device for simulating natural gas hydrate formation includes an experimental container 100, a first closing mechanism 200 is provided in the experimental container 100, and a second closing mechanism 300 is provided at the bottom. The experimental container 100 includes an experimental cylinder 120, a ring knife 130 is placed in the experimental cylinder 120, the first closing mechanism 200 includes an upper permeable stone 250, and the second closing mechanism 300 includes a first bottom plate 320 and a second bottom plate 330. A lower permeable stone 331 is placed on the upper part of the second bottom plate 330. The first bottom plate 320 and the second bottom plate 330 can revolve around the midpoint of the line connecting the centers of the first bottom plate 320 and the second bottom plate 330, so that the first bottom plate 320 or the second bottom plate 330 can block the experimental cylinder 120. When the upper permeable stone 250 moves upward and the first bottom plate 320 blocks the bottom of the experimental cylinder 120, the experimental cylinder 120 is in an experimental state. When the upper permeable stone 250 moves downward and the second bottom plate 330 blocks the bottom of the experimental cylinder 120, the experimental cylinder 120 is in a permeability detection state.

[0038] The working mechanism of the experimental equipment for simulating natural gas hydrate formation provided in this embodiment is as follows:

[0039] The device also includes a gas source system, a reaction system, a temperature and pressure regulation system, a detection system and a control system. The methane gas source is connected to the bottom air inlet of the experimental cylinder 120 in the constant temperature box through pipelines, valves and flanges, a silent air compressor, a gas booster pump, a gas storage container, a valve-controlled flow meter and a check valve to provide methane gas for the reaction. The upper part of the experimental cylinder 120 is provided with a temperature measuring port, an umbrella-shaped gas-liquid separator and other interfaces, a filter pressure plate 321 is provided inside, and a circular ring knife 130 is provided at the bottom to simulate the seabed sediment environment and monitor the reaction process. The constant temperature box controls the temperature of the experimental cylinder 120. The gas storage container is connected to the hand pump through pipelines, valves and flanges via a back pressure valve and a buffer tank to adjust the pressure. Various sensors such as temperature measuring sensors and methane leak alarms are respectively connected to the control system to monitor various parameters in the reaction process in real time.

[0040] The experimental process of the device is as follows: equipment construction and preparation: prepare simulated seawater, real seawater or sediment samples in the study area according to research requirements, connect methane gas source, silent air compressor, gas booster pump and other equipment, install each sensor in the corresponding position of the experimental cylinder 120, and check the circuit, sensor and leakage;

[0041] Simulating submarine environmental conditions: Using a thermostat to control the temperature within the test tube 120 at 0-20°C to simulate a low-temperature submarine environment, a hand-cranked pump and a buffer tank are used to set a back pressure of 3-30 MPa for the back-pressure valve. Using a methane gas source, a compressor, and a booster pump, methane gas is injected into the test tube 120 and pressurized to simulate a high-pressure submarine environment and methane seepage. Simulated seawater or real seawater is then injected into the test tube 120, along with various sediments and microorganisms to simulate submarine water chemical composition and microbial conditions, minimizing the shallow sedimentary environment of a methane-rich fluid seepage on the seafloor.

[0042] Hydrate formation monitoring: Twelve temperature sensors, one gas pressure sensor, and one seawater salinity sensor are connected to both sides of the experimental tube 120 to monitor methane temperature and pressure, and liquid seawater temperature and salinity in real time. This allows the start and end of hydrate formation, as well as changes in temperature, pressure, and seawater salinity during the process, to be captured. A ring cutter 130 of the same size installed at the bottom of the experimental tube 120 is used to monitor sediment seepage characteristics before and after hydrate formation, analyzing the impact of hydrate formation on sediment permeability.

[0043] Data acquisition and analysis: Open the computer data acquisition system in the control and display system, set the acquisition items and parameters, display the monitoring data history curve in real time, collect water and gas samples through the liquid sampling port and gas sampling port, and test the chemical composition. After the experiment, analyze the chemical composition and microbial characteristics of the water samples. Use X-ray diffraction, scanning electron microscopy and other methods to analyze the changes in sediment samples. Comprehensively obtain various information on the hydrate formation process to provide data support for the study of the hydrate formation mechanism and its associated environmental effects;

[0044] When testing the permeability of the sample in the ring knife 130, if there is liquid in the test cylinder 120, the liquid will be discharged through the discharge pipe at the bottom of the first bottom plate 320, and the upper permeable stone 250 will be controlled to move downward to block the upper port of the ring knife 130. Then, the first bottom plate 320 will be controlled to move out of the bottom of the test cylinder 120, so that the second bottom plate 330 moves to the bottom of the test cylinder 120, so that the lower permeable stone 331 blocks the lower port of the ring knife 130. At this time, water is passed into the upper permeable stone 250, and the water penetrates the upper permeable stone 250 and the sample and is discharged through the lower permeable stone 331, which means that the permeability of the sample is tested. By setting the upper permeable stone 250 in the test cylinder 120 and moving the lower permeable stone 331 to the lower part of the test cylinder 120, the water permeability of the sample can be tested without taking the ring knife 130 and the sample inside it out of the test cylinder 120, thereby simplifying the experimental steps.

[0045] Regarding the structure of the first closing mechanism 200, specifically:

[0046] The first closing mechanism 200 further includes a receiving chamber 210 fixedly connected to the experimental cylinder 120. The upper permeable stone 250 can enter / move out of the receiving chamber 210. A semicircular ring 230 is fixedly connected to the edge of the upper permeable stone 250. After the upper permeable stone 250 enters the semicircular ring 230, the semicircular ring 230 can block the opening of the receiving chamber 210.

[0047] The setting of the accommodating chamber 210 protects the upper permeable stone 250. When the upper permeable stone 250 is completely in the accommodating chamber 210, the semicircular ring 230 can block the opening of the accommodating chamber 210. At this time, the accommodating chamber 210 is in a closed state, thereby protecting the upper permeable stone 250 and preventing the liquid in the experimental cylinder 120 from affecting the upper permeable stone 250.

[0048] Among the optional methods of this embodiment, the more preferred ones are:

[0049] Both ends of the semicircular ring 230 are fixedly connected to a rotating shaft 240, and a gear 241 is fixedly connected to the rotating shaft 240. The inner wall of the experimental cylinder 120 is provided with two sliding grooves 121 for the two rotating shafts 240 to slide. A side wall in the middle of the sliding groove 121 is provided with teeth 122 that cooperate with the gear 241. When the rotating shaft 240 moves downward to allow the gear 241 to mesh with the teeth 122, the upper permeable stone 250 is separated from the accommodating chamber 210.

[0050] The rotating shaft 240 can slide vertically in the slide groove 121. When the gear 241 does not contact the teeth 122, the upper permeable stone 250 is still partially in the accommodating chamber 210. At this time, the upper permeable stone 250 can be in a vertical state. When the gear 241 contacts the teeth 122, the upper permeable stone 250 is completely separated from the accommodating chamber 210, so that the accommodating chamber 210 no longer blocks the flipping of the upper permeable stone 250. As the rotating shaft 240 continues to move downward, the gear 241 can roll on the teeth 122, so that the rotating shaft 240 drives the upper permeable stone 250 to flip to a horizontal state.

[0051] Among the optional methods of this embodiment, the more preferred ones are:

[0052] A notch 242 is provided on the rotating shaft 240, and a ridge 123 is provided on the opposite side of the tooth 122 in the slide groove 121. When the rotating shaft 240 moves downward, the tooth 122 is at the lower part, and the upper permeable stone 250 flips ninety degrees, and the notch 242 is engaged with the ridge 123, so that the upper permeable stone 250 moves downward in a horizontal state to block the upper port of the ring knife 130.

[0053] When the upper permeable stone 250 is flipped to a horizontal state, the gear 241 just disengages from the teeth 122, and the protrusion 123 is engaged in the notch 242 on the rotating shaft 240. At this time, the rotating shaft 240 can no longer rotate, and then the rotating shaft 240 slides down in the slide groove 121 until the upper permeable stone 250 blocks the upper port of the ring knife 130.

[0054] Among the optional methods of this embodiment, the more preferred ones are:

[0055] The top of the test tube 120 is fixedly connected to a cylinder 220 , and the output end of the cylinder 220 is rotatably connected to the rotating shaft 240 .

[0056] The output end of the cylinder 220 passes through the top wall of the test tube 120 and is rotatably connected to the rotating shaft 240. Thus, the extension and contraction of the cylinder 220 can drive the rotating shaft 240 to move up and down. A sealing ring is provided at the contact point between the cylinder rod of the cylinder 220 and the test tube 120 to ensure the sealing of the test tube 120.

[0057] When the cylinder 220 is shortened, the rotating shaft 240 moves upward. When the protrusion 123 disengages from the notch 242, the gear 241 contacts and rolls on the teeth 122, causing the upper permeable stone 250 to flip to a vertical state. When the upper permeable stone 250 is in the vertical state, the cylinder 220 continues to shorten. At this time, the upper permeable stone 250 contacts the inner wall of the accommodating chamber 210. When the cylinder 220 continues to contract, the upper permeable stone 250 is stored in the accommodating chamber 210.

[0058] Regarding the structure of the second closing mechanism 300, specifically:

[0059] The second closing mechanism 300 also includes a connecting block 310, a first bottom plate 320 and a second bottom plate 330 symmetrically connected to both sides of the connecting block 310, and a threaded rod 341 is threadedly connected to the middle part of the connecting block 310. The threaded rod 341 can drive the connecting block 310 to rotate and move axially. When the threaded rod 341 drives the connecting block 310 to rotate, the first bottom plate 320 or the second bottom plate 330 can move to the bottom of the experimental cylinder 120, and when the threaded rod 341 drives the connecting block 310 to move axially, the first bottom plate 320 and the second bottom plate 330 can move upward, thereby blocking the bottom of the experimental cylinder 120.

[0060] A motor 340 is fixedly connected to the mounting base 110, and a threaded rod 341 is connected to the output end of the motor 340. When the motor 340 is started, the threaded rod 341 is driven to rotate slowly. When the first base plate 320, the second base plate 330 and the connecting block 310 are not blocked, the threaded rod 341 can drive the connecting block 310 to rotate, thereby causing the first base plate 320 and the second base plate 330 to revolve around the threaded rod 341 as the center, thereby exchanging the positions of the first base plate 320 and the second base plate 330. When any of the first base plate 320, the second base plate 330 or the connecting block 310 is blocked, the threaded rod 341 continues to rotate to drive the connecting block 310 to move up or down, causing the first base plate 320 and the second base plate 330 to move closer to or away from the experimental cylinder 120, thereby switching the state of the experimental cylinder 120.

[0061] Among the optional methods of this embodiment, the more preferred ones are:

[0062] The experimental container 100 also includes a mounting base 110, and the experimental cylinder 120 is fixedly connected to the mounting base 110. Two hydraulic rods 350 are symmetrically fixedly connected to the mounting base 110 on both sides of the experimental cylinder 120. The output ends of the two hydraulic rods 350 are fixedly connected to the limit blocks 360. After the two limit blocks 360 move upward, the threaded rod 341 can drive the connecting block 310 to rotate. When the first bottom plate 320 or the second bottom plate 330 moves to the lower part of the experimental cylinder 120, the limit block 360 moves downward to abut against the side wall of the first bottom plate 320 or the second bottom plate 330, so that the threaded rod 341 can drive the connecting block 310 to move axially.

[0063] When switching the positions of the first base plate 320 and the second base plate 330, first, the control chain hydraulic rods 350 are extended, so that the two limit blocks 360 move downward, and the two sides of the first base plate 320 are limited. At this time, the control motor 340 is reversed, so that the threaded rod 341 is reversed, so that the connecting block 310 moves axially downward on the threaded rod 341. At this time, the first base plate 320 and the second base plate 330 move downward synchronously, and then the first base plate 320 drives the filter pressing plate 321 connected thereto to move downward and disconnect from the experimental cylinder 120. Then, the control hydraulic rod 350 is shortened, so that the limit blocks 360 move upward, so that the first base plate 320 is no longer limited, and the control motor 340 is rotated forward or reverse. When the second bottom plate 330 is at the bottom of the test tube 120, the hydraulic rod 350 is controlled to extend. At this time, the limit block 360 moves downward to limit the second bottom plate 330, so that the second bottom plate 330 can no longer revolve around the threaded rod 341. Then the threaded rod 341 continues to rotate forward, driving the connecting block 310 to move upward, so that the second bottom plate 330 moves upward and is close to the bottom of the test tube 120. At the same time, the lower permeable stone 331 blocks the lower port of the ring knife 130. At this time, the experimental sample is ready, and the water permeability test of the sample in the ring knife 130 can be carried out.

[0064] Among the optional methods of this embodiment, the more preferred ones are:

[0065] The first closing mechanism 200 also includes a water storage container 280. The bottom of the water storage container 280 is connected to a drain pipe 270. The drain pipe 270 is connected to a vertical pipe 260. The vertical pipe 260 is connected to the upper permeable stone 250. The vertical pipe 260 is connected to a pressure measuring tube 271. A connecting pipe 261 is connected between the vertical pipe 260 and the drain pipe 270. The pressure measuring tube 271 is connected to a scale 272.

[0066] According to the operating steps of the variable water head permeation device, the switches of each pipeline are controlled and the sample in the ring knife 130 is exhausted, thereby completing the detection of the water permeability of the sample in the ring knife 130;

[0067] A guide wheel 290 is fixedly connected to the top of the test tube 120 and rotates on a fixed axis. A pull rope 291 is driven on the guide wheel 290. One end of the pull rope 291 is fixedly connected to the vertical pipe 260, and the other end is connected to a counterweight 292. Therefore, when the upper permeable stone 250 moves up and down, the counterweight 292 always applies an upward force to the vertical pipe 260, ensuring that the vertical pipe 260 does not interfere with the movement of the upper permeable stone 250.

[0068] In addition, the semicircular ring 230 is connected to an upper cover. When the upper permeable stone 250 is turned over to a horizontal state, the upper cover is located above the upper permeable stone 250, the vertical pipe 260 is connected to the upper cover, and the upper permeable stone 250 is located inside the upper cover.

[0069] Among the optional methods of this embodiment, the more preferred ones are:

[0070] A water outlet pipe 333 is connected to the second bottom plate 330 , and the water outlet pipe 333 is connected to the lower permeable stone 331 .

[0071] Sealing rings are provided at the edges of the upper permeable stone 250 and the lower permeable stone 331 to prevent water from overflowing from the edge of the port of the ring knife 130. A placement tray 332 is connected to the second bottom plate 330, and the lower permeable stone 331 is placed on the placement tray 332. The water outlet pipe 333 is connected to the groove on the placement tray 332 for placing the lower permeable stone 331.

[0072] An experimental method for simulating natural gas hydrate formation, applied to an experimental device for simulating natural gas hydrate formation, comprises the following steps:

[0073] When measuring permeability, the liquid in the test tube 120 is emptied, and the cylinder 220 is controlled to extend. The cylinder 220 drives the semicircular ring 230 to move the upper permeable stone 250 downward out of the accommodating chamber 210. When the gear 241 engages with the teeth 122, the upper permeable stone 250 is separated from the accommodating chamber 210. The cylinder 220 continues to extend, and the gear 241 rolls on the teeth 122, causing the upper permeable stone 250 to flip to a horizontal state. At the same time, the convex strip 123 is engaged with the notch 242. The cylinder 220 continues to extend, causing the upper permeable stone 250 to move downward in a horizontal state until it covers the upper end of the ring cutter 130.

[0074] The hydraulic rod 350 is controlled to extend so that the two limit blocks 360 abut against the side walls of the first bottom plate 320, and the threaded rod 341 is controlled to reverse, so that the connecting block 310 drives the first bottom plate 320 and the second bottom plate 330 to move downward synchronously. After the first bottom plate 320 is separated from the experimental cylinder 120, the hydraulic rod 350 is controlled to shorten, and the threaded rod 341 continues to rotate 180 degrees, so that the second bottom plate 330 moves to the lower part of the experimental cylinder 120. The hydraulic rod 350 is controlled to extend so that the two limit blocks 360 abut against the side walls of the second bottom plate 330, and the threaded rod 341 is controlled to rotate forward, so that the connecting block 310 drives the first bottom plate 320 and the second bottom plate 330 to move upward synchronously, and the lower permeable stone 331 blocks the lower port of the ring knife 130, so that both ports of the ring knife 130 are closed.

[0075] The water in the water storage container 280 is released, and the permeability test is performed on the sample in the ring knife 130.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An experimental device for simulating the formation of natural gas hydrates, characterized by: The invention comprises an experimental container (100), wherein a first closing mechanism (200) is provided in the experimental container (100), and a second closing mechanism (300) is provided at the bottom. The experimental container (100) comprises an experimental cylinder (120), wherein a ring knife (130) is placed in the experimental cylinder (120), the first closing mechanism (200) comprises an upper permeable stone (250), the second closing mechanism (300) comprises a first bottom plate (320) and a second bottom plate (330), a lower permeable stone (331) is placed on the upper part of the second bottom plate (330), and the first bottom plate (320) and the second bottom plate (330) can revolve around the midpoint of the line connecting the centers of the two, so that the first bottom plate (320) or the second bottom plate (330) can block the experimental cylinder (120), and when the upper permeable stone (250) moves upward and the first bottom plate (320) blocks the bottom of the experimental cylinder (120), the experimental cylinder (120) is in an experimental state, and when the upper permeable stone (250) moves downward and the second bottom plate (330) blocks the bottom of the experimental cylinder (120), the experimental cylinder (120) is in a permeability detection state.

2. The experimental device for simulating natural gas hydrate formation according to claim 1, characterized in that: The first closing mechanism (200) further comprises a receiving cavity (210) fixedly connected to the inside of the experimental cylinder (120), the upper permeable stone (250) being capable of entering / moving out of the receiving cavity (210), a semicircular ring (230) being fixedly connected to the edge of the upper permeable stone (250), and after the upper permeable stone (250) enters the semicircular ring (230), the semicircular ring (230) is capable of blocking the opening of the receiving cavity (210).

3. The experimental device for simulating natural gas hydrate formation according to claim 2, characterized in that: Both ends of the semicircular ring (230) are fixedly connected to a rotating shaft (240), and a gear (241) is fixedly connected to the rotating shaft (240). The inner wall of the experimental cylinder (120) is provided with two sliding grooves (121) for the two rotating shafts (240) to slide. A side wall in the middle of the sliding groove (121) is provided with teeth (122) that cooperate with the gear (241). When the rotating shaft (240) moves downward to allow the gear (241) to mesh with the teeth (122), the upper permeable stone (250) is separated from the accommodating cavity (210).

4. The experimental device for simulating natural gas hydrate formation according to claim 3, characterized in that: A notch (242) is provided on the rotating shaft (240), and a convex strip (123) is provided in the slide groove (121) on the opposite side of the tooth (122). When the rotating shaft (240) moves downward and the tooth (122) is at the lower part, the upper permeable stone (250) turns ninety degrees, and the notch (242) is engaged with the convex strip (123), so that the upper permeable stone (250) moves downward in a horizontal state to block the upper port of the ring knife (130).

5. The experimental device for simulating natural gas hydrate formation according to claim 4, characterized in that: The top of the experimental cylinder (120) is fixedly connected to a cylinder (220), and the output end of the cylinder (220) is rotatably connected to the rotating shaft (240).

6. The experimental device for simulating natural gas hydrate formation according to claim 5, characterized in that: The second closing mechanism (300) further includes a connecting block (310), the first bottom plate (320) and the second bottom plate (330) are symmetrically connected to both sides of the connecting block (310), and a threaded rod (341) is threadedly connected to the middle part of the connecting block (310), and the threaded rod (341) can drive the connecting block (310) to rotate and move axially. When the threaded rod (341) drives the connecting block (310) to rotate, the first bottom plate (320) or the second bottom plate (330) can move to the bottom of the experimental cylinder (120), and when the threaded rod (341) drives the connecting block (310) to move axially, the first bottom plate (320) and the second bottom plate (330) can move upward, thereby blocking the bottom of the experimental cylinder (120).

7. The experimental device for simulating natural gas hydrate formation according to claim 6, characterized in that: The experimental container (100) further comprises a mounting seat (110), the experimental cylinder (120) is fixedly connected to the mounting seat (110), two hydraulic rods (350) are symmetrically fixedly connected to the mounting seat (110) on both sides of the experimental cylinder (120), the output ends of the two hydraulic rods (350) are fixedly connected to limit blocks (360), after the two limit blocks (360) move upward, the threaded rod (341) can drive the connecting block (310) to rotate, and when the first bottom plate (320) or the second bottom plate (330) moves to the lower part of the experimental cylinder (120), the limit block (360) moves downward to abut against the side wall of the first bottom plate (320) or the second bottom plate (330), so that the threaded rod (341) can drive the connecting block (310) to move axially.

8. The experimental device for simulating natural gas hydrate formation according to claim 7, characterized in that: The first closing mechanism (200) further comprises a water storage container (280), the bottom of the water storage container (280) being connected to a drain pipe (270), the drain pipe (270) being connected to a vertical pipe (260), the vertical pipe (260) being connected to the upper permeable stone (250), the vertical pipe (260) being connected to a pressure measuring pipe (271), and a connecting pipe (261) being connected between the vertical pipe (260) and the drain pipe (270).

9. The experimental device for simulating natural gas hydrate formation according to claim 8, characterized in that: A water outlet pipe (333) is connected to the second bottom plate (330), and the water outlet pipe (333) is connected to the lower permeable stone (331).

10. An experimental method for simulating the formation of natural gas hydrates, applied to the experimental device for simulating the formation of natural gas hydrates according to claim 9, characterized in that: The following steps are involved: When measuring permeability, the liquid in the test tube (120) is emptied, and the cylinder (220) is controlled to extend. The cylinder (220) drives the semicircular ring (230) to drive the upper permeable stone (250) to move downward out of the accommodating chamber (210). When the gear (241) is engaged with the teeth (122), the upper permeable stone (250) is separated from the accommodating chamber (210). The cylinder (220) continues to extend, and the gear (241) rolls on the teeth (122), causing the upper permeable stone (250) to flip to a horizontal state. At the same time, the convex strip (123) is engaged with the notch (242). The cylinder (220) continues to extend, causing the upper permeable stone (250) to move downward in a horizontal state until the upper permeable stone (250) covers the upper end of the ring cutter (130). The hydraulic rod (350) is controlled to extend so that the two limit blocks (360) abut against the side wall of the first bottom plate (320), and the threaded rod (341) is controlled to reverse so that the connecting block (310) drives the first bottom plate (320) and the second bottom plate (330) to move downward synchronously. After the first bottom plate (320) is separated from the test cylinder (120), the hydraulic rod (350) is controlled to shorten and the threaded rod (341) continues to rotate 180 degrees so that the second bottom plate ( After the test tube (330) moves to the lower part of the test tube (120), the hydraulic rod (350) is controlled to extend so that the two limit blocks (360) abut against the side wall of the second bottom plate (330), and the threaded rod (341) is controlled to rotate forward so that the connecting block (310) drives the first bottom plate (320) and the second bottom plate (330) to move upward synchronously, and the lower permeable stone (331) blocks the lower port of the ring knife (130), so that both ports of the ring knife (130) are closed; The water in the water storage container (280) is released, and the permeability test is performed on the sample in the ring knife (130).

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