Visual experiment device and method for simulating splitting grouting of deep sea hydrate reservoir

Abstract

The invention relates to the technical field of argillaceous silt type natural gas hydrate exploitation simulation, and discloses a visual experiment device and method for simulating deep sea hydrate reservoir splitting grouting, and a visual reservoir splitting grouting cylinder comprises a transparent cylinder body for filling a transparent sample and a grouting pipe arranged in the transparent cylinder body; the pressure load module comprises a grouting mechanism and a stress loading mechanism, the grouting mechanism is communicated with the grouting pipe, and the stress loading mechanism is used for providing vertical stress for the transparent sample in the transparent cylinder to simulate vertical ground stress; the data acquisition module comprises a temperature and pressure data acquisition system, a plurality of high-definition and high-frequency cameras and a computer, researchers can more intuitively observe the whole fracturing and grouting process of the natural gas hydrate reservoir and the crack initiation-expansion path of slurry in the reservoir, and the crack initiation mechanism of the natural gas hydrate reservoir is clarified; and the understanding of the splitting grouting process is deepened.

Description

Technical Field

[0001] The present invention relates to the technical field of simulation of the exploitation of argillaceous silt-type natural gas hydrates, and particularly to a visualization experimental device and method for simulating the splitting grouting of deep-sea natural gas hydrate reservoirs. Background Art

[0002] Natural gas hydrate is a new type of energy source, an ice-like compound formed by natural gas molecules and water molecules under high pressure and low temperature conditions, namely "flammable ice", which mainly exists in submarine sediments and permafrost zones. The global resource amount of natural gas hydrates is huge. It is estimated that its carbon content can reach twice the total carbon content of the proven fossil fuels.

[0003] At present, the exploitation technology of natural gas hydrates in the sea area is not yet mature. After the hydrates decompose under pressure reduction, the mechanical properties of the reservoir change greatly, and the strength of the reservoir skeleton decreases, resulting in the reduction or even closure of the crack width and the failure of reservoir reconstruction.

[0004] Most of the existing splitting grouting experiments are based on invisible experimental devices. The splitting grouting of argillaceous silt-type reservoirs is carried out, and after the slurry solidifies, the grout veins are taken out to observe the expansion behavior of the slurry. The existing methods can only take out the final form of the grout veins after consolidation, and cannot obtain the expansion path and flow characteristics of the slurry in the reservoir in real time, which is not conducive to the research of the slurry expansion mechanism by researchers. Summary of the Invention

[0005] The purpose of the present invention is to provide a visualization experimental device and method for simulating the splitting grouting of deep-sea natural gas hydrate reservoirs, aiming to solve or improve at least one of the above technical problems.

[0006] To achieve the above purpose, the present invention provides the following solutions: The present invention provides a visualization experimental device for simulating the splitting grouting of deep-sea natural gas hydrate reservoirs, including:

[0007] A visualization reservoir splitting grouting cylinder, including a transparent cylinder body for loading a transparent specimen and a grouting pipe arranged in the transparent cylinder body. During the experiment, the inside of the transparent cylinder body is in a vacuum state;

[0008] A pressure load module, including a grouting mechanism and a stress loading mechanism. The grouting mechanism is connected to the grouting pipe and is used for injecting slurry and displacing the slurry in the grouting pipe. The stress loading mechanism is used to provide a vertical stress to the transparent specimen in the transparent cylinder body to simulate the vertical in-situ stress;

[0009] A data acquisition module, including a temperature and pressure data acquisition system, a plurality of high-definition high-frequency cameras, and a computer. The temperature and pressure data acquisition system is used to monitor the changes in grouting pressure, vertical stress, and temperature. The high-definition high-frequency cameras are used to monitor the expansion of the slurry in the transparent specimen in real time.

[0010] Optionally, the transparent cylinder body includes a glass cylinder, and an upper cover plate and a lower cover plate arranged at both ends of the glass cylinder. The upper cover plate and the lower cover plate are connected by a plurality of first columns and first nuts, and an avoidance hole for the stress loading mechanism to pass through is formed in the upper cover plate.

[0011] Optionally, the stress loading mechanism includes:

[0012] A vertical stress loading platform;

[0013] A pressure-resistant plate, arranged in the avoidance hole, and the pressure-resistant plate is used to contact the transparent specimen;

[0014] A small cover plate, connected to the pressure-resistant plate by a plurality of second columns and second nuts, and the small cover plate is used to connect to the vertical stress loading platform.

[0015] Optionally, the grouting pipe is coaxially arranged with the transparent cylinder body.

[0016] Optionally, a needle valve for communicating with the inner cavity of the glass cylinder is arranged on the pressure-resistant plate.

[0017] Optionally, the grouting mechanism includes a first piston tank and a second piston tank communicated with the grouting pipe through a double-pass interface, a constant-speed and constant-flow pump for driving the liquid in the first piston tank and the second piston tank, and a control valve for switching the communication state between the first piston tank and the second piston tank and the constant-speed and constant-flow pump. Slurry is arranged in the first piston tank, and displacement liquid is arranged in the second piston tank.

[0018] Optionally, the temperature and pressure data acquisition system is connected with a plurality of temperature and pressure sensors.

[0019] Optionally, it further includes a laser emitter for providing laser irradiation to the transparent cylinder body.

[0020] Optionally, the bottom end of the grouting pipe is connected to the lower cover plate by fixing screws.

[0021] The present invention also provides a visualization experimental method for simulating the splitting grouting of a deep-sea gas hydrate reservoir, including the following steps:

[0022] Configure the transparent specimen;

[0023] Load the transparent specimen into the transparent cylinder body;

[0024] Vacuum the transparent cylinder body;

[0025] Vertically stress the transparent specimen in the transparent cylinder body through the pressure load module, and inject slurry into the transparent specimen;

[0026] The pressure, temperature, and dynamic expansion of the slurry are recorded in real time through the data acquisition module;

[0027] After the slurry solidifies, the transparent specimen is taken out to analyze the morphology and expansion law of the slurry veins.

[0028] The present invention discloses the following technical effects:

[0029] By setting a transparent cylinder and a transparent specimen, and cooperating with a temperature and pressure data acquisition system and multiple high-definition and high-frequency cameras, when a grouting experiment is carried out through a grouting mechanism and a stress loading mechanism, researchers can more intuitively observe the whole process of split grouting in a natural gas hydrate reservoir and the crack initiation - propagation path of the slurry in the reservoir, clarify the crack initiation mechanism of the natural gas hydrate reservoir, and deepen the understanding of the split grouting process.

[0030] The high-definition video recording of the slurry expansion in the reservoir obtained from the experiment can clearly show the reservoir crack initiation and slurry expansion conditions, and the video data is simple to store and easy to spread, which can help researchers communicate the test results across regions.

[0031] The present invention inherits the traditional split grouting experimental method, and at the same time overcomes the drawback that the traditional physical experiment can only obtain the expansion range of the slurry veins after the experiment. It creatively manufactures a visual reservoir split device and reasonably uses fused quartz sand and pore solution as transparent specimens, which can monitor the reservoir split and crack initiation dynamics in real time and the expansion of the slurry in the reservoir, helping researchers clarify the crack initiation of the natural gas hydrate reservoir and the expansion mechanism of the slurry in the reservoir, and providing an experimental basis for the research on the natural gas hydrate reservoir transformation method. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The drawings constituting a part of this application are used to provide a further understanding of this application. The schematic embodiments of this application and their descriptions are used to explain this application and do not constitute an improper limitation to this application. In the drawings:

[0033] Figure 1 is a schematic diagram of the overall structure of the present invention;

[0034] Figure 2 is a schematic diagram of the structure of the visual reservoir split grouting cylinder of the present invention;

[0035] Figure 3 is a cross-sectional view of the visual reservoir split grouting cylinder of the present invention.

[0036] In the figure: 1. Data acquisition module; 2. Visual reservoir splitting grouting cylinder; 3. Pressure load module; 4. Temperature and pressure sensor; 5. Constant speed and constant flow pump; 6. First piston tank; 7. Control valve; 8. Second piston tank; 9. Vertical stress loading platform; 10. High-definition and high-frequency camera; 11. Temperature and pressure data acquisition system; 12. Computer; 13. Second nut; 14. Small cover plate; 15. Second column; 16. First nut; 17. Pressure-resistant plate; 18. Sealing ring; 19. Upper cover plate; 20. First column; 21. Glass cylinder; 22. Lower cover plate; 23. Grouting pipe; 24. Needle valve; 25. Double-pass interface; 26. Fixed screw; 27. Laser emitter. Detailed implementation mode

[0037] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0038] In order to make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation modes.

[0039] Refer to Figures 1 - 3 , the present invention provides a visual experimental device for simulating deep-sea hydrate reservoir splitting grouting, including:

[0040] The visual reservoir splitting grouting cylinder 2 includes a transparent cylinder for loading a transparent specimen and a grouting pipe 23 arranged in the transparent cylinder. During the experiment, the inside of the transparent cylinder is in a vacuum state;

[0041] The pressure load module 3 includes a grouting mechanism and a stress loading mechanism. The grouting mechanism is connected to the grouting pipe 23 and is used to inject slurry and displace the slurry in the grouting pipe 23. The stress loading mechanism is used to provide vertical stress to the transparent specimen in the transparent cylinder to simulate vertical in-situ stress;

[0042] The data acquisition module 1 includes a temperature and pressure data acquisition system 11, a plurality of high-definition and high-frequency cameras 10, and a computer 12. The temperature and pressure data acquisition system 11 is used to monitor the grouting pressure, vertical stress, and temperature changes. The high-definition and high-frequency cameras 10 are used to monitor the expansion of the slurry in the transparent specimen in real time.

[0043] By setting up a transparent cylinder and a transparent specimen, and cooperating with a temperature and pressure data acquisition system and multiple high-definition and high-frequency cameras, during the grouting experiment carried out by the grouting mechanism and the stress loading mechanism, researchers can more intuitively observe the whole process of split grouting in the natural gas hydrate reservoir and the crack initiation - propagation path of the grout in the reservoir, clarify the crack initiation mechanism of the natural gas hydrate reservoir, and deepen the understanding of the split grouting process.

[0044] Furthermore, the transparent specimen is synthesized by mixing molten quartz sand and pore solution, has certain elasticity and plasticity, can effectively simulate the mechanical properties of the marine muddy siltstone hydrate reservoir to a certain extent, and can restore the original mechanical characteristics of the reservoir as much as possible. The transparent specimen with basically the same mechanical properties as various hydrate reservoirs can be flexibly prepared by adjusting the transparent soil formula.

[0045] Furthermore, specifically, there are two high-definition and high-frequency cameras 10, respectively facing the front and back of the glass cylinder 21, to monitor the expansion of the grout in the reservoir in real time.

[0046] In an embodiment of the present invention, the transparent cylinder includes a glass cylinder 21, and an upper cover plate 19 and a lower cover plate 22 arranged at both ends of the glass cylinder 21. The upper cover plate 19 and the lower cover plate 22 are connected by a plurality of first columns 20 and first nuts 16, and an avoidance hole for the stress loading mechanism to pass through is opened on the upper cover plate 19.

[0047] The glass cylinder 21, the upper cover plate 19 and the lower cover plate 22 are effectively reinforced by the first columns 20, so that the transparent cylinder has high pressure resistance, is simple to manufacture, has low cost and light weight, and meets the use requirements in various test sites.

[0048] In an embodiment of the present invention, the stress loading mechanism includes:

[0049] A vertical stress loading platform 9;

[0050] A pressure-resistant plate 17, arranged in the avoidance hole, and the pressure-resistant plate 17 is used to contact the transparent specimen;

[0051] A small cover plate 14, connected to the pressure-resistant plate 17 by a plurality of second columns 15 and second nuts 13, and the small cover plate 14 is used to connect to the vertical stress loading platform 9.

[0052] The small cover plate 14 is loaded by the vertical stress loading platform 9, and then the pressure-resistant plate 17 is driven by the second columns 15 to perform synchronous pressurization operation on the transparent specimen.

[0053] In an embodiment of the present invention, the grouting pipe 23 is coaxially arranged with the transparent cylinder. This enables the grout to have sufficient flow space in the transparent specimen, effectively improves the flow effect of the grout, and improves the test accuracy.

[0054] In one embodiment of the present invention, a needle valve 24 is provided on the pressure-resistant plate 17 for communicating with the inner cavity of the glass cylinder 21. The needle valve 24 is used to evacuate the air in the transparent cylinder and saturate the soil to remove paraffin, creating a vacuum environment.

[0055] In one embodiment of the present invention, the grouting mechanism includes a first piston tank 6 and a second piston tank 8 connected to the grouting pipe 23 through a double-pass interface 25, a constant-speed and constant-flow pump 5 for driving the liquid in the first piston tank 6 and the second piston tank 8, and a control valve 7 for switching the connection state between the first piston tank 6 and the second piston tank 8 and the constant-speed and constant-flow pump 5. A slurry is provided in the first piston tank 6, and a displacement liquid is provided in the second piston tank 8.

[0056] The constant-speed and constant-flow pump 5 drives the slurry in the first piston tank 6 to inject the slurry toward the grouting pipe 23, and the constant-speed and constant-flow pump 5 drives the displacement liquid in the second piston tank 8 to displace the remaining slurry in the grouting pipe 23.

[0057] In one embodiment of the present invention, the temperature and pressure data acquisition system 11 is connected with a plurality of temperature and pressure sensors 4. The plurality of temperature and pressure sensors 4 are distributed on the pipelines of the grouting mechanism, the side wall of the transparent cylinder, and the vertical stress loading platform 9 for monitoring the grouting pressure, vertical stress, and temperature changes.

[0058] In one embodiment of the present invention, a laser emitter 27 is further included for providing laser irradiation to the transparent cylinder. The laser emitter 27 adjusts to a suitable angle and emits laser to irradiate the entire area of the glass cylinder 21, making the slurry expansion behavior clearer. The analog modulation frequency of the laser emitter 27 can reach 3 MHz, and the wavelength coverage range is wide.

[0059] In one embodiment of the present invention, the bottom end of the grouting pipe 23 is connected to the lower cover plate 22 through a fixing screw 26.

[0060] Furthermore, the grouting pipe 23 penetrates through the pressure-resistant plate 17. Sealing rings 18 are provided between the grouting pipe 23 and the pressure-resistant plate 17, and between the pressure-resistant plate 17 and the upper cover plate 19 to improve the overall sealing effect of the device.

[0061] Furthermore, a through hole for connecting to a vacuum pump is provided on the lower cover plate 22.

[0062] The present invention also provides a visualization experimental method for simulating the splitting grouting of deep-sea hydrate reservoirs, including the following steps:

[0063] According to the experimental purpose, the experimental system is completely built and it is checked whether the experimental device is in a normal working state, and it is confirmed whether the experimental device is well sealed.

[0064] Configure a transparent specimen, simulate the marine sediment reservoir with fused quartz sand and saturate it with the corresponding pore solution. Repeatedly adjust the formula to ensure that its mechanical properties are basically the same as those of the actual reservoir.

[0065] Load the transparent specimen into the transparent cylinder body, tightly cover the pressure-resistant plate 17, and use the first nut 16 to fix the upper cover plate 19 and the lower cover plate 22, and press the glass cylinder 21 tightly;

[0066] Vacuum the transparent cylinder body, connect the through hole on the lower cover plate 22 to the vacuum pump, so that the transparent specimen is completely saturated and infiltrated by the pore solution, cooperate with the needle valve 24 to evacuate the air in the transparent cylinder body and saturate the soil body to remove paraffin, creating a vacuum environment;

[0067] Connect the constant-speed and constant-flow pump 5 with the first piston tank 6 and the second piston tank 8 using a stainless-steel pressure-resistant pipeline. At the same time, install a temperature and pressure sensor 4 on the connecting pipeline of the double-pass interface 25; connect the constant-speed and constant-flow pump 5 with the temperature and pressure data acquisition system 11 at the same time; aim the two high-definition and high-frequency cameras 10 at the front and back of the glass cylinder 21, set up the laser generator 27 and adjust the angle to make the irradiation effect reach the best;

[0068] Apply vertical stress loading to the transparent specimen in the transparent cylinder body through the pressure load module, and inject slurry into the transparent specimen; record the pressure, temperature and slurry expansion dynamics in real time through the data acquisition module. Specifically, close the needle valves 24 and the control valve 7 everywhere, start the vertical stress loading platform 9, adjust the gas cylinder pressure reducing valve until it is adjusted to the pressure value required by the experiment, start the temperature and pressure data acquisition system 11, turn on the high-definition and high-frequency cameras 10 and the laser emitter 27, inject the prepared slurry into the first piston tank 6 and connect the corresponding pipelines, start the constant-speed and constant-flow pump 5 to pump the slurry into the grouting pipe 23 at the grouting rate required by the experiment, gradually split the transparent specimen, use the temperature and pressure data acquisition system 11 to record the whole process changes of the temperature and pressure during the pumping process, use the high-definition and high-frequency cameras 10 to record the whole process of the slurry splitting the reservoir and the dynamic expansion range of the slurry. After all the slurry in the first piston tank 6 is injected into the visual reservoir splitting grouting cylinder, close the control valve 7, start the second piston tank 8, inject the reservoir displacement fluid until all the displacement fluid in the second piston tank 8 is injected, save the data of the temperature and pressure data acquisition system 11, and then turn off the high-definition and high-frequency cameras 10 and the temperature and pressure data acquisition system 11;

[0069] Take out the transparent specimen after the slurry solidifies, and analyze the shape and expansion law of the grout veins. Specifically, after the slurry is fully solidified for 24 hours, unload the vertical ground stress and close the vertical stress loading platform 9, remove the small cover plate 14 and the pressure-resistant plate 17, take out the transparent specimen, observe, take pictures and record the final shape of the solidified slurry.

[0070] Dismantle the experimental device and clean the pipelines and the experimental device.

[0071] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be construed as a limitation to the present invention.

[0072] The embodiments described above are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the spirit of the design of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A visual experimental device for simulating the splitting grouting of a deep-sea gas hydrate reservoir, characterized in that, Comprising: A visual reservoir split grouting cylinder (2), including a transparent cylinder body for loading a transparent specimen and a grouting pipe (23) arranged inside the transparent cylinder body. During the experiment, the inside of the transparent cylinder body is in a vacuum state; A pressure load module (3), including a grouting mechanism and a stress loading mechanism. The grouting mechanism is connected to the grouting pipe (23) and is used to inject slurry and displace the slurry in the grouting pipe (23). The stress loading mechanism is used to provide a vertical stress to the transparent specimen inside the transparent cylinder body to simulate the vertical in-situ stress; A data acquisition module (1), including a temperature and pressure data acquisition system (11), multiple high-definition high-frequency cameras (10) and a computer (12). The temperature and pressure data acquisition system (11) is used to monitor the grouting pressure, vertical stress and temperature changes. The high-definition high-frequency cameras (10) are used to monitor the expansion of the slurry in the transparent specimen in real time.

2. The visualization experimental device for simulating the splitting grouting of deep-sea hydrate reservoirs according to claim 1, wherein, The transparent cylinder body includes a glass cylinder (21) and upper and lower covers (19, 22) arranged at both ends of the glass cylinder (21). The upper cover (19) and the lower cover (22) are connected by a plurality of first columns (20) and first nuts (16). An avoidance hole for the stress loading mechanism to pass through is provided on the upper cover (19).

3. The visualization experimental device for simulating split grouting in deep-sea hydrate reservoirs according to claim 2, characterized in that, The stress loading mechanism includes: A vertical stress loading platform (9); A pressure-resistant plate (17), arranged in the avoidance hole. The pressure-resistant plate (17) is used to contact the transparent specimen; A small cover plate (14), connected to the pressure-resistant plate (17) by a plurality of second columns (15) and second nuts (13). The small cover plate (14) is used to connect to the vertical stress loading platform (9).

4. A visual experimental device for simulating the splitting grouting of deep-sea hydrate reservoirs according to claim 1, characterized in that, The grouting pipe (23) is coaxially arranged with the transparent cylinder body.

5. The visualization experimental device for simulating the splitting grouting of deep-sea hydrate reservoirs according to claim 3, characterized in that, A needle valve (24) for communicating with the inner cavity of the glass cylinder (21) is arranged on the pressure-resistant plate (17).

6. The visual experimental device for simulating the splitting grouting of deep-sea hydrate reservoirs according to claim 1, wherein, The grouting mechanism includes a first piston tank (6) and a second piston tank (8) connected to the grouting pipe (23) through a two-way interface (25), a constant-speed constant-flow pump (5) for driving the liquid in the first piston tank (6) and the second piston tank (8), and a control valve (7) for switching the connection state between the first piston tank (6) and the second piston tank (8) and the constant-speed constant-flow pump (5). Slurry is arranged in the first piston tank (6), and displacement liquid is arranged in the second piston tank (8).

7. The visualization experimental device for simulating the splitting grouting of deep-sea hydrate reservoirs according to claim 1, wherein The temperature and pressure data acquisition system (11) is connected with a plurality of temperature and pressure sensors (4).

8. A visualization experimental device for simulating the splitting grouting of deep-sea hydrate reservoirs according to claim 1, characterized in that It further includes a laser emitter (27) for providing laser irradiation to the transparent cylinder body.

9. The visualization experimental device for simulating the splitting grouting of deep-sea hydrate reservoirs according to claim 2, wherein The bottom end of the grouting pipe (23) is connected to the lower cover (22) by a fixing screw (26).

10. A visualization experimental method for simulating the splitting grouting of deep-sea hydrate reservoirs, based on the visualization experimental device for simulating the splitting grouting of deep-sea hydrate reservoirs according to any one of claims 1-9, characterized in that, Including the following steps: Configuring the transparent specimen; Loading the transparent specimen into the transparent cylinder body; Vacuumizing the transparent cylinder body; Applying vertical stress loading to the transparent specimen in the transparent cylinder body through the pressure load module and injecting slurry into the transparent specimen; Recording the pressure, temperature and slurry expansion dynamics in real time through the data acquisition module; After the slurry is solidified, take out the transparent specimen and analyze the morphology and expansion law of the slurry veins.

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