CN111551671A

CN111551671A - System and method for natural gas hydrate decomposition methane leakage and cold spring ecological simulation

Info

Publication number: CN111551671A
Application number: CN202010223932.8A
Authority: CN
Inventors: 冯景春; 张偲; 杨志峰; 蔡宴鹏; 孙龙涛; 郑红波
Original assignee: Guangdong University of Technology; Southern Marine Science and Engineering Guangdong Laboratory Guangzhou
Current assignee: Guangdong University of Technology; Southern Marine Science and Engineering Guangdong Laboratory Guangzhou
Priority date: 2020-03-26
Filing date: 2020-03-26
Publication date: 2020-08-18
Anticipated expiration: 2040-03-26
Also published as: CN111551671B

Abstract

The system and the method for simulating natural gas hydrate decomposition methane leakage and cold spring ecosystem provided by the invention have the advantages that the function of cooperative simulation of natural gas hydrate decomposition and methane leakage behaviors is realized, the migration transformation of leaked gas in the process of passing through an overlying deposition layer is combined with the development of a cold spring system and the development of the cold spring ecosystem, and the marine natural gas hydrate reservoir, the overlying deposition layer and a leakage channel, a seabed interface and a seawater environment system can be simulated and remolded in situ, so that the research on the scientific problems of natural gas hydrate formation evolution, gas migration transformation related to natural gas hydrate decomposition leakage, reservoir sedimentation, development of the cold spring system, development of the cold spring ecosystem and the like is realized.

Description

System and method for natural gas hydrate decomposition methane leakage and cold spring ecological simulation

Technical Field

The invention relates to the technical field of ocean engineering, in particular to a natural gas hydrate decomposed methane leakage and cold spring ecological simulation system and method.

Background

The natural gas hydrate is commonly called as combustible ice and is widely applied to seabed sediments at the edge of continents, the global storage amount is up to two billions of cubic meters, the carbon content of the natural gas hydrate is 2 times of the carbon storage amount of all fossil fuels found in the world, 160-180 m3 of natural gas can be released by each cubic meter of the natural gas hydrate under the standard state, and the amount of carbon dioxide discharged during combustion is only 24% of the amount of the fossil fuels. Because of the characteristics of large reserves, high energy density, wide distribution, no pollution and residue after combustion and the like, the natural gas hydrate is praised as a substitute energy source with the greatest prospect in the 21 st century.

Gaseous methane generated after the natural gas hydrate is decomposed is transported to the seabed along the fracture channel to overflow, and a cold spring is formed on the seabed. The leaked fluid provides abundant nutrients for some microorganisms (bacteria and archaea) which are synthesized by means of chemotherAN _ SNy, forms a food chain with chemotherAN _ SNy autotrophic bacteria as primary producers, and develops a complete seabed cold spring ecosystem with very unique community structure. The discovery of the cold spring biological group taking methane as energy and carbon source expands the potential boundary of life in the deep sea extreme environment, explains the meaning of life by brand-new face, simultaneously the biological density of the cold spring system is high and the biological diversity is low, the diversity of metabolites and abundant gene resources are inoculated, the unprecedented opportunity is provided for discovering new microbial metabolic pathways and survival strategies, and the leading edge scientific research of the cold spring ecosystem has important significance for disclosing unknown deep sea extreme life processes.

However, at present, the interaction relationship between the methane leakage decomposed by natural gas hydrate and the development of the seabed cold spring is not clearly defined, and the current research on natural gas hydrate and the research on the ecological system of the cold spring and the cold spring are in a splitting state. The existing research on the natural gas hydrate simulation technology is limited to the research on natural gas hydrates in natural gas hydrate reservoirs, basic physical property parameters of reservoirs, decomposition phase change of the natural gas hydrates, heat transfer, mass transfer and reservoir deformation. The methane leakage mechanism of the natural gas hydrate decomposition reservoir is not clear, and the migration and conversion mechanism of the leaked methane gas escaping from the interface on the natural gas hydrate reservoir in the leakage path of the overlying sedimentary deposit is almost in a blank state. At present, the research on the deep-sea cold spring mainly comes from the observation research on the migration forms of cold spring fluid such as cold spring bubbles, cold spring plumes and the like in the seabed in situ, and the research on the expression forms of the cold spring such as cold spring carbonates and the like in the seabed, most of the sources of the cold spring fluid are suspected to come from the decomposition of natural gas hydrates at the lower part of the seabed, however, the specific association between the methane leakage decomposition of the natural gas hydrates and the dynamic mechanism of the cold spring development is not clear, and the existing research on the cold spring development is not actually associated with the formation and decomposition of the natural gas hydrates. The interrelationship of methane leakage flux at the boundaries of natural gas hydrate reservoirs and sedimentary formations, methane flux into sedimentary leak paths, and methane flux of cold springs escaping at the seafloor is not well understood. The relationship between cold spring development and the evolution of the cold spring ecosystem needs to be deeply researched to reveal the mysterious veil of the deep sea extreme life development. In-situ seabed detection tests can only observe limited fragmentation data of seabed units, and in the prior art, the evolution relationship between natural gas hydrates below seabed sediments and cold spring development above a seabed interface and a cold spring ecosystem is difficult to intuitively and transparently research. With the development of deep sea simulation technology, a large-scale comprehensive deep sea simulation experiment device is established, and the whole process of simulating methane leakage decomposition of natural gas hydrate below the sea bottom, cold spring development and cold spring ecosystem formation evolution is a necessary means for solving the basic scientific problems of environment ecology in natural gas hydrate development and the basic scientific problems at the front edge of a cold spring system.

Disclosure of Invention

The invention provides a system and a method for simulating methane leakage decomposition of natural gas hydrate and cold spring ecology, aiming at overcoming the technical defects that the existing large-scale comprehensive deep sea simulation experiment device is not used for simulating the whole process of methane leakage decomposition of natural gas hydrate below the sea bottom, cold spring development and cold spring ecosystem evolution formation, and the basic scientific problems of the environment ecology of natural gas hydrate development and the basic scientific problems of the front edge of the cold spring system cannot be solved.

In order to solve the technical problems, the technical scheme of the invention is as follows:

the natural gas hydrate decomposed methane leakage and cold spring ecological simulation system comprises a natural gas hydrate forming decomposition system, a leakage passage simulation system and a cold spring ecological simulation system; wherein:

the natural gas hydrate forming and decomposing system is used for simulating the formation and decomposition of marine natural gas hydrate;

the natural gas hydrate formation decomposition system is connected with the cold spring ecological simulation system through the leakage passage simulation system;

the leakage passage simulation system is used for simulating and observing the migration and transformation behaviors of gas leaked from the natural gas hydrate formation decomposition system into the cold spring ecological simulation system;

the cold spring ecological simulation system is used for simulating the process of gas development of the cold spring and the ecological system thereof through the leakage passage simulation system, and the simulation of the evolution of the cold spring ecological system is realized.

The natural gas hydrate decomposition methane leakage and cold spring ecological simulation method comprises a natural gas hydrate formation decomposition process, a gas leakage process and a cold spring ecological system construction process, wherein:

the natural gas hydrate forming and decomposing process is to simulate the forming and decomposing process of the marine natural gas hydrate through the natural gas hydrate forming and decomposing system;

the gas leakage process is specifically a migration and transformation behavior of gas leaked from a natural gas hydrate formation decomposition system into a cold spring ecological simulation system is simulated and observed through the leakage passage simulation system;

the construction process of the cold spring ecosystem is specifically a process of carrying out cold spring development and ecosystem evolution on leaked gas through simulation of a cold spring ecological simulation system, so that the construction of the cold spring ecosystem is completed.

Compared with the prior art, the technical scheme of the invention has the beneficial effects that:

Drawings

FIG. 1 is a schematic structural diagram of a natural gas hydrate decomposition methane leakage and cold spring ecological simulation system;

FIG. 2 is a schematic diagram of a natural gas hydrate formation decomposition system circuit module connection;

FIG. 3 is a schematic diagram of a leakage path simulation system circuit module connection;

FIG. 4 is a schematic diagram of the connection of the circuit module of the ecological simulation system for cold spring;

FIG. 5 is a schematic flow diagram of a decomposition process for formation of natural gas hydrates;

FIG. 6 is a schematic flow diagram of a simulation process for a gas leak-off process including a fracture-free type;

FIG. 7 is a schematic flow diagram of a simulation process for a gas leak-off process including a fracture-containing type;

FIG. 8 is a schematic flow chart of the construction process of the ecological system of the cold spring;

wherein: 1. a natural gas hydrate formation decomposition system; 11. a natural gas hydrate reservoir simulation cavity; 111. a cavity; 112. a simulation layer; 1121. covering a deposition layer; 1122. a natural gas hydrate reservoir; 1123. an underlying gas-liquid mixing layer; 12. a first pressure sensor; 13. a formation temperature control system; 131. a first temperature sensor; 132. a ring wall temperature control system; 1321. a temperature controller; 1322. a water bath circulation jacket; 1323. an external heat exchanger unit; 1324. an electromagnetic valve; 133. a heat exchanger is arranged inside; 14. a displacement sensor; 15. a gas-liquid injection system; 151. a gas injection subsystem; 1511. a high pressure gas source; 1512. an air compressor; 1513. a gas booster pump; 1514. a buffer container; 1515. a first control valve; 1516. a gas flow meter; 152. a liquid injection subsystem; 1521. a seawater storage tank; 1522. a high pressure seawater injection pump; 1523. a seawater mass flow meter; 1524. a second control valve; 16. a production well system; 161. a horizontal production well; 162. a vertical production well; 163. a third control valve; 17. a production system; 171. a back pressure subsystem; 172. a gas-liquid-solid three-phase separation device; 173. a water storage tank; 174. a gas collector; 175. a fourth control valve; 18. an acquisition control system; 181. a processor; 182. a human-computer interaction module; 19. an alarm device; 2. a leakage path simulation system; 21. a pressure-resistant pipeline; 22. a flow rate regulating device; 23. a flow rate metering device; 24. a fluid form monitoring device; 3. a cold spring ecological simulation system; 31. a high pressure simulation chamber; 32. subsea interface above unit; 33. a submarine interface ecosystem simulation unit; 34. a subsea interface below unit; 341. building a system by a simulation layer; 3411. a sulfur-containing solution reservoir; 3412. saturated oxygen solution; 3413. an injection pump; 3414. a mass flow meter; 3415. a controllable valve bank; 342. a chemical zonal simulation layer for the submarine sediments; 3421. an anaerobic oxidation zone; 3422. a sub-oxygen oxidation zone; 3423. an oxygen-containing oxidation zone; 35. an environmental condition control device; 351. a second temperature sensor; 352. a ring wall temperature control device; 353. a second pressure sensor; 354. a gas-liquid circulation device; 355. a light source device; 356. a metering device; 357. a sampling device; 358. a processing terminal; 3581. a data acquisition unit; 3582. a central processing unit; 3583. a memory; 3584. a display; 36. a sampling cabin; 361. an inside hatch door; 362. an outboard hatch door; 363. a pressure detector; 364. a pressure balancing unit; 3641. a drainage system; 3642. an exhaust system; 365. a moving guide rail; 366. a sampler; 37. the subsea flow injection system.

Detailed Description

The drawings are for illustrative purposes only and are not to be construed as limiting the patent;

for the purpose of better illustrating the embodiments, certain features of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product;

it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted.

The technical solution of the present invention is further described below with reference to the accompanying drawings and examples.

Example 1

As shown in fig. 1, the natural gas hydrate decomposition methane leakage and cold spring ecological simulation system comprises a natural gas hydrate formation decomposition system 1, a leakage passage simulation system 2 and a cold spring ecological simulation system 3; wherein:

the natural gas hydrate forming and decomposing system 1 is used for simulating the formation and decomposition of marine natural gas hydrate;

the natural gas hydrate formation and decomposition system 1 is connected with the cold spring ecological simulation system 3 through the leakage passage simulation system 2;

the leakage passage simulation system 2 is used for simulating and observing the migration and transformation behaviors of gas leaked from the natural gas hydrate formation and decomposition system 1 into the cold spring ecological simulation system 3;

the cold spring ecological simulation system 3 performs cold spring development on the gas obtained by the leakage passage simulation system 2, so as to realize simulation of the cold spring ecological system.

In the specific implementation process, the natural gas hydrate decomposition and leakage are simulated through the natural gas hydrate forming and decomposing system 1, the migration transformation of leaked gas in the passing of an overlying deposition layer is combined with the development of a cold spring system and the formation and evolution of the cold spring ecosystem, and the marine natural gas hydrate reservoir, the overlying deposition layer and leakage passage simulation system 2, a seabed interface and a seawater environment system are simulated and remolded in situ in the cold spring ecosystem simulation system 3, so that the research on the scientific problems of the formation and evolution of the natural gas hydrate, the gas migration transformation related to the natural gas hydrate decomposition and leakage, the reservoir sedimentation, the development of the cold spring system, the formation and evolution of the cold spring ecosystem and the like is realized.

In the specific implementation process, the methane leakage technology of the natural gas hydrate decomposition reservoir is simulated by the natural gas hydrate formation decomposition system 1 and the leakage path simulation system 2, compared with the existing hydrate simulation technology which mainly focuses on the scientific problems in the natural gas hydrate reservoir, the research boundary that leaked methane enters the upper interface after leaking from the natural gas hydrate reservoir is expanded, and a research platform is provided for the important scientific problems such as the environmental ecological effect of methane leakage exploitation of natural gas hydrates, deep-sea methane carbon cycle and the like.

In the specific implementation process, the cold spring development technology is simulated through the cold spring ecological simulation system 3, and the cold spring development and the natural gas hydrate decomposition are directly linked, so that the problem that the existing cold spring research is mainly based on limited seabed observation is avoided, most cold spring fluid sources are only guessed from the assumed state of the natural gas hydrate decomposition under the seabed, the relationship between the natural gas hydrate decomposition and the cold spring development can be further deeply known, and the dynamic mechanism of the cold spring development is clarified.

In the specific implementation process, the invention provides a means and a basis for directly correlating the decomposition of the natural gas hydrate with the formation and evolution of the cold spring ecosystem and providing key points for knowing the material environmental conditions of the formation and evolution of the cold spring ecosystem, the influence degree of the development of the natural gas hydrate on the deep sea ecosystem and the like.

Example 2

More specifically, as shown in fig. 1 and 2, the natural gas hydrate formation decomposition system 1 includes:

the natural gas hydrate reservoir simulation cavity 11 comprises a cavity 111 and a plurality of simulation layers 112 arranged inside the cavity 111;

the formation temperature control system 13 comprises a first temperature sensor 131 arranged in the simulation layer 112, an internal heat exchanger 133 arranged in the cavity 111 and a ring wall temperature control system 132 arranged on the outer wall of the cavity 111, the first temperature sensor 131 is in signal connection with the ring wall temperature control system 132, and the internal heat exchanger 133 is electrically connected with the ring wall temperature control system 132;

the gas-liquid injection system 15 is communicated with the bottom of the cavity 111;

a production well system 16 disposed inside the cavity 111;

the production system 17 is connected with the output end of the production well system 16, and the output end of the production system 17 is connected with the input end of the gas-liquid injection system 15;

a first pressure sensor 12 disposed in the simulated layer 112;

a displacement sensor 14 disposed in the simulation layer 112;

the acquisition control system 18 is electrically connected with the first pressure sensor 12, the annular wall temperature control system 132, the gas-liquid injection system 15, the production system 17 and the displacement sensor 14;

the leakage path simulation system 2 is arranged at the top of the cavity 11 and is electrically connected with the acquisition control system 18.

In the specific implementation process, the natural gas hydrate formation and decomposition system 1 is used for realizing in-situ geological layering construction of the sea natural gas hydrate reservoir, and the geological environment system simulation requirement of the large-scale natural gas hydrate formation and decomposition process is met. Compared with a small-scale simulation system, the method can more accurately invert seepage rules, heat transfer and mass transfer characteristics in the natural gas hydrate reservoir stratum in the natural gas hydrate formation and decomposition processes, and make up for the defect that the small-scale simulation system is difficult to realize pressure gradient change in the real natural gas hydrate reservoir stratum; meanwhile, the system is used for simulating the formation and decomposition geological environment of the natural gas hydrate, so that the experimental period is effectively shortened, the experimental cost is greatly reduced, the law can be searched through repeated tests, and the risk of the field test on the surrounding ecological environment system is reduced; finally, compared with the existing numerical simulation research means, the method can be developed based on the actual natural gas hydrate deposition sample, the experimental model is closer to the actual state, and the defects that the numerical theory research has more assumed conditions, the parameter conditions are too rational and the like are overcome.

More specifically, the cavity 111 is a large-scale simulation cavity with a diameter of 3 meters and a height of 5 meters; the simulation layer 112 comprises an overlying sedimentary layer 1121, a natural gas hydrate reservoir 1122 and an underlying gas-liquid mixed layer 1123 which are sequentially arranged from top to bottom; wherein:

a plurality of first pressure sensors 12 and a plurality of first temperature sensors 131 are respectively and uniformly arranged in each simulation layer 112;

a plurality of displacement sensors 14 are fixed at the bottom of the overlying sedimentary deposit 1121 at equal intervals and are arranged in the gas hydrate reservoir 1122;

a plurality of built-in heat exchangers 133 are fixed on top of the underlying gas-liquid mixed layer 1123 at equal intervals and arranged in the gas hydrate reservoir 1122;

the production well system 16 is disposed in the natural gas hydrate reservoir 1122 with its output connected to the production system 17 through the overburden 1121.

In the specific implementation process, natural gas hydrate is injected into the large-scale natural gas hydrate reservoir simulation cavity 11 through the gas-liquid injection system 15 to form required gas-liquid fluid, then the formation temperature control system 13 and the first pressure sensor 12 are adjusted, geological environment conditions such as temperature and pressure required by formation of the natural gas hydrate are simulated in situ, after a required natural gas hydrate sample is formed in a required time period, the exploitation well system 16 and the production system 17 can be opened, the required exploitation mode is used for achieving the processes of natural gas hydrate decomposition, gas-liquid output collection and the like, and in the natural gas hydrate decomposition process, the vertical settlement change of the natural gas hydrate reservoir 1122 is monitored in real time through the displacement sensor 14. The invention can realize geological environment system simulation and real-time data acquisition, processing, image output and storage in the natural gas hydrate forming and decomposing process, and can carry out safety monitoring on the surrounding environment in the whole natural gas hydrate forming and decomposing process.

In the specific implementation process, the large-scale natural gas hydrate reservoir simulation cavity 11 related by the invention is a core component, the diameter and the height of which are meter-level, so that the purposes of truly simulating a seepage field, a heat transfer field and a mass transfer field in the natural gas hydrate formation and decomposition process and analyzing the phase change of the natural gas hydrate formation and decomposition process and the heat and mass transfer and gas flow characteristics in the reservoir are met. The inner wall of the natural gas hydrate reservoir simulation cavity 11 related by the invention has an anti-corrosion function, and the high-pressure, low-temperature and salt-containing environment in which the natural gas hydrate in the sea area exists can be simulated for a long time by using an anti-corrosion stainless steel material or overlaying an anti-corrosion coating on the inner wall.

In the specific implementation process, the internal dimensions of the gas hydrate reservoir simulation cavity 11 meet the geological stratification requirements of the gas hydrate reservoir 1122, the overlying sedimentary layer 1121 and the underlying gas-liquid mixed layer 1123. The gas-liquid injection system 15 mainly fulfills the functions of injecting gas and liquid into the gas hydrate reservoir 1122 and the underlying gas-liquid mixed layer 1123 and the overlying deposition layer 1121. The underbump gas-liquid mixture layer 1123 is filled with a gas-liquid fluid such as methane gas, a methane-ethane mixture gas, a saturated methane liquid, or a gas-water mixture in a predetermined amount in accordance with the actual situation. In the natural gas hydrate reservoir 1122, mainly liquids and gases such as seawater, methane, ethane and the like required for forming the natural gas hydrate, and hot fluids and chemical reagents and the like required for decomposing the natural gas hydrate are injected into the natural gas hydrate reservoir simulation cavity 11 in the natural gas hydrate decomposition process.

In the specific implementation process, the gas-liquid injection system 15 provided by the invention is provided with interfaces at the top, the bottom and the side wall of the natural gas hydrate reservoir simulation cavity 11, so that the requirements of different gas-liquid injection modes are met, and the key problems of the formation of the natural gas hydrate caused by the change of the gas-liquid injection mode, the heat and mass transfer law of the decomposition of the natural gas hydrate in different injection modes and the like can be researched.

In the specific implementation process, the first pressure sensor 12 according to the present invention is mainly used for pressure detection of different geological horizons, such as an overlying sedimentary layer 1121, a natural gas hydrate reservoir 1122, and an underlying gas-liquid mixed layer 1123; and injecting quantitative gas-liquid fluid required by each layer at different positions according to the in-situ address environmental data, arranging the first pressure sensors 12 at different positions, and monitoring the pressure environmental change of the bottom layer in real time.

In a specific implementation process, the displacement sensors 14 are uniformly distributed in the gas hydrate reservoir 1122, so that displacement settlement inside the gas hydrate reservoir 1122 caused by pressure propagation, gas-liquid flow and the like in a gas hydrate decomposition process is monitored in real time.

More specifically, the annular wall temperature control system 132 comprises a temperature controller 1321, a water bath circulation jacket 1322 and an external heat exchanger unit 1323; wherein:

the water bath circulation jacket 1322 is wrapped on the outer wall of the cavity 111, and pipelines are arranged at the top and the bottom of the water bath circulation jacket 1322 and are connected with the external heat exchanger unit 1323 through the pipelines; the pipeline is provided with an electromagnetic valve 1324;

the control end of the electromagnetic valve 1324, the control end of the external heat exchanger unit 1323 and the control end of the internal heat exchanger 133 are electrically connected with the output end of the temperature controller 1321;

the input end of the temperature controller 1321 is electrically connected with the output end of the first temperature sensor 131;

the temperature controller 1321 is electrically connected with the acquisition control system 18 to realize information interaction.

In the implementation process, the annular wall temperature control system 132 mainly satisfies the temperature simulation and monitoring of different geological horizons such as the overlying sedimentary layer 1121, the natural gas hydrate reservoir 1122, and the underlying gas-liquid mixed layer 1123. The annular wall temperature control system 132 can realize ground temperature gradient simulation of a seabed environment, and is realized by wrapping a water bath circulating jacket 1322 on the outer wall and the bottom of a natural gas hydrate reservoir simulation cavity 11 and arranging a built-in heat exchanger 133 group with fixed power in the natural gas hydrate reservoir simulation cavity; the low-temperature environment of the natural gas hydrate reservoir 1122 in the natural gas hydrate forming process can be realized, the earth temperature gradient change from top to bottom of the overlying sedimentary layer 1121, the natural gas hydrate reservoir 1122, the underlying gas-liquid mixed layer 1123 and the like is truly inverted, and the temperature error is controlled within 0.5 ℃ per kilometer. Meanwhile, the natural gas hydrate reservoir 1122 and the upper and lower non-environmental systems related to the invention have large volumes and large surface areas, so that formation temperature change in the decomposition process of the natural gas hydrate can be realized, and bottom layer temperature cloud change can be really inverted.

More specifically, the gas-liquid injection system 15 includes a gas injection subsystem 151 and a liquid injection subsystem 152; wherein:

the input end of the gas injection subsystem 151 is connected with the output end of the production system 17;

the control end of the gas injection subsystem 151 is electrically connected with the acquisition control system 18 to realize information interaction;

the output end of the gas injection subsystem 151 is communicated with the bottom of the cavity 111 and is used for injecting gas into the cavity 111;

the control end of the liquid injection subsystem 152 is electrically connected with the acquisition control system 18 to realize information interaction;

the output end of the liquid injection subsystem 152 is communicated with the bottom of the cavity 111 and is used for injecting liquid into the cavity.

More specifically, the gas injection subsystem 151 includes a high pressure gas source 1511, an air compressor 1512, a gas booster pump 1513, a buffer vessel 1514, a first control valve 1515 and a gas flow meter 1516; wherein:

the output end of the high-pressure air source 1511 is connected with the input end of the buffer container 1514 through the first control valve 1515;

the air compressor 1512 is connected with the input end of the buffer container 1514 through the gas booster pump 1513;

the output end of the production system 17 is connected with the input end of the buffer container 1514 through the first control valve 1515;

the output end of the buffer container 1514 is provided with the gas flow meter 1516, and the signal output end of the gas flow meter 1516 is electrically connected with the input end of the acquisition control system 18;

the output end of the buffer container 1514 is communicated with the bottom of the cavity 111 through the first control valve 1515;

the air compressor 1512, the gas booster pump 1513, the first control valve 1515 and the control end of the gas flow meter 1516 are electrically connected to the collection control system 18.

More specifically, the liquid injection subsystem 152 includes a seawater storage tank 1521, a high-pressure seawater injection pump 1522, a seawater mass flow meter 1523, and a second control valve 1524; wherein:

the output end of the seawater storage tank 1521 is connected with the input end of the high-pressure seawater injection pump 1522 through the second control valve 1524;

the seawater mass flowmeter 1523 is arranged at the output end of the high-pressure seawater injection pump 1522, and the signal output end of the seawater mass flowmeter 1523 is electrically connected with the input end of the acquisition control system 18;

the output end of the high-pressure seawater injection pump 1522 is communicated with the bottom of the cavity 111 through the second control valve 1524;

the high-pressure seawater injection pump 1522, the seawater mass flowmeter 1523 and the control end of the second control valve 1524 are electrically connected with the acquisition control system 18.

In a specific implementation, the air compressor 1512 is used to drive the gas booster pump 1513, and the gas booster pump 1513 is a boosting element; the gas injection subsystem 151 does not generate gas, and mainly pressurizes and fills the gas in the high-pressure gas source 1511 into the buffer container 1514, and then injects the gas into the system through the buffer container 1514; since the gas pressurization process involves severe pressure fluctuations, buffer vessel 1514 is required to smooth out the pressure of the injected gas for metering.

More specifically, the production well system 16 includes a horizontal production well 161, a vertical production well 162, and a third control valve 163; wherein:

the horizontal production well 161 is disposed horizontally in the natural gas hydrate reservoir 1122; the vertical production well 162 is vertically disposed in the natural gas hydrate reservoir 1122;

the horizontal production well 161 and the vertical production well 162 are uniformly provided with perforations which wrap a plurality of layers of sand control nets;

the output ends of the horizontal production well 161 and the vertical production well 162 are connected with the input end of the production system 17 through the third control valve 163;

the control end of the third control valve 163 is electrically connected to the acquisition control system 18.

In the specific implementation process, the horizontal production well 161 and the vertical production well 162 with the real size (the diameter is 89mm) are distributed in the natural gas hydrate reservoir 1122 by the production well system 16, the natural gas hydrate production by the single horizontal well/single vertical well/vertical well combined horizontal well can be simulated, the vertical well and the horizontal well are uniformly provided with the perforations, and the perforated wells are externally wrapped by a plurality of layers of sand prevention nets to prevent the sand blocking phenomenon at the well hole position in the gas-liquid production process.

In the specific implementation process, the sand control net is arranged to only prevent larger particles, and sand with smaller particles does not have the risk of blockage and is output to the production system 17 through the horizontal production well 161 and the vertical production well 162.

More specifically, the production system 17 includes a back pressure subsystem 171, a gas-liquid-solid three-phase separation device 172, a water storage tank 173, a gas collector 174, and a fourth control valve 175; wherein:

the input end of the back pressure subsystem 171 is connected with the third control valve 163, and the output end of the back pressure subsystem 171 is connected with the input end of the gas-liquid-solid three-phase separation device 172;

the liquid output end of the gas-liquid-solid three-phase separation device 172 is connected with the input end of the water storage tank 173 through the fourth control valve 175;

the gas output end of the gas-liquid-solid three-phase separation device 172 is connected with the input end of the gas collector 174 through the fourth control valve 175;

the output of the gas accumulator 174 is connected to the input of the buffer vessel 1514 via the first control valve 1515;

the back pressure subsystem 171 and the control end of the fourth control valve 175 are electrically connected to the collection control system 18.

In one implementation, the back pressure subsystem 171 is a back pressure valve for controlling the outlet pressure.

More specifically, the acquisition control system 18 includes a processor 181 and a human-computer interaction module 182, where the human-computer interaction module 182 is electrically connected to the processor 181 to implement information interaction;

the processor 181 is electrically connected to the pressure sensor 12, the annular wall temperature control system 132, the gas-liquid injection system 15, the production system 17, the leakage path simulation system 2, and the displacement sensor 14.

In a specific implementation process, the acquisition control system 18 realizes the functions of real-time acquisition, processing, storage, image output and the like of various environmental data information changes of the formation in the natural gas hydrate forming and decomposing process through the processor 181 and the human-computer interaction module 182.

In the specific implementation process, the system is further provided with an alarm device 19 for early warning and forecasting of leakage of combustible substances such as methane in the natural gas hydrate formation and decomposition processes, high-pressure monitoring inside the natural gas hydrate reservoir 1122 and the like, and the safety of the surrounding environment system in the natural gas hydrate formation and decomposition processes is guaranteed.

In the specific implementation process, geological stratification is realized in the natural gas hydrate reservoir simulation cavity 11, seawater is filled in the lower-pressure gas-liquid mixed layer 1123, silty sediment serving as a porous medium is filled in the natural gas hydrate reservoir 1122, and a calcareous clay layer is filled in the upper sediment layer 1121; injecting pre-calculated quantitative methane gas and seawater into the natural gas hydrate reservoir 1122 through the gas-liquid injection system 15, respectively adjusting the temperature and pressure of each layer in the simulation cavity 11 of the natural gas hydrate reservoir, ensuring that the natural gas hydrate forms the required high-pressure and low-temperature environment, and forming the natural gas hydrate; when the natural gas hydrate saturation reaches the preset design value (35%), the production well system 16 is opened to carry out depressurization or other decomposition on the natural gas hydrate; the temperature and pressure distribution and change conditions of each layer in the decomposition process of the natural gas hydrate are monitored and recorded in real time through the first temperature sensor 131 and the first pressure sensor 12; monitoring and recording the displacement settlement of the natural gas hydrate reservoir 1122 in real time through a displacement sensor 14; gas production, water production, sand production and rate are collected and recorded by the production system 17 until the natural gas hydrate synthesized in the natural gas hydrate reservoir 1122 is completely decomposed, and the simulation of forming a decomposed geological environment by the natural gas hydrate is completed.

In the specific implementation process, the natural gas hydrate formation decomposition system 1 can generate methane gas and gas-liquid mixed fluid containing methane, and the gas/liquid can be leaked to the cold spring ecological simulation system 3 through the leakage passage simulation system 2, so that a fluid leakage source is provided for the simulation of the cold spring ecological simulation system 3.

Example 3

More specifically, as shown in fig. 1 and 3, the leakage path simulation system 2 includes a plurality of pressure-resistant pipes 21, a flow rate adjusting device 22, a flow rate metering device 23, and a fluid form monitoring device 24; wherein:

one end of the pressure-resistant pipeline 21 is arranged on the cavity 111, and the other end of the pressure-resistant pipeline is arranged at the bottom of the cold spring ecological simulation system 3, so that the cavity 111 is communicated with the cold spring ecological simulation system 3;

each pressure-resistant pipeline 21 is internally provided with a flow rate regulating device 22 and a flow rate metering device 23;

the fluid form monitoring device 24 is mounted on the pressure-resistant pipe 21;

the input end of the acquisition control system 18 is electrically connected with the output ends of the flow rate metering device 23 and the fluid form monitoring device 24;

the output end of the acquisition control system 18 is electrically connected with the control ends of the flow rate regulating device 22, the flow rate metering device 23 and the fluid form monitoring device 24.

More specifically, the pressure-resistant pipe 21 is a transparent structure, and the fluid form monitoring device 24 is mounted on the outer wall of the transparent pressure-resistant pipe 21.

In a specific implementation process, when the pressure-resistant pipeline 21 is an opaque pipeline, the fluid form monitoring device 95 is installed inside the pipeline and is used for monitoring the migration behavior of the gas-liquid fluid in the pressure-resistant pipeline 21 in a channel in real time; when the pressure-resistant pipeline 21 is a transparent pipeline, the fluid form monitoring device 24 is a high-definition fluid form monitoring device, and can be installed on the outer wall of the pipeline, so that the migration behavior of the gas-liquid fluid in the pressure-resistant pipeline 21 can be monitored conveniently.

In the specific implementation process, the fluid form monitoring device 24 is mainly used for observing the migration characteristic and the evolution characteristic of leaked gas-liquid fluid in a pipeline by an observation element arranged in or outside the channel; the flow rate adjusting device 22 is mainly a regulating device installed in the channel, and a system capable of being manually or automatically opened and closed adjusts the flow rate of the fluid in the channel; the flow rate metering device 23 meters the magnitude of the fluid flow actually leaking in the passage.

In the specific implementation process, relevant research results of characteristics and natural gas hydrate decomposition leakage behaviors are researched according to geological environment exploration data, and the research results relate to actual channel shapes, distribution, sizes and materials and are installed. Filling porous media in a crack-free passage according to the distribution, the pore diameter and the saturation parameters of each phase of the porous media in an actual sediment layer, and relating to a pipeline system which is jointly distributed in the vertical direction, the horizontal direction, the oblique direction and different directions according to actual exploration and survey data; and then, opening the leakage passage partially or completely according to the requirement, simulating and researching the migration behavior of the leaked methane and liquid in the passage after the natural gas hydrate is decomposed, synchronously or orderly adjusting the flow velocity of each passage, and simulating, observing and researching the migration and conversion behavior of the methane-containing fluid in the passage at different leakage rates. During the whole process of fluid leakage, the migration characteristics of the fluid in the passages are observed through the fluid form monitoring device 24, the leakage rate and the evolution condition of the fluid in each passage are measured through the flow rate measuring device 23, and data and images are recorded, processed and output in real time in the acquisition control system 18.

In the specific implementation process, compared with the existing natural gas hydrate simulation system which is used for simulating and researching the formation and decomposition conditions of the natural gas hydrate in the natural gas hydrate reservoir, the simulation research provided by the invention is used for simulating and researching the leakage behavior of the leaked methane-containing fluid in the natural gas hydrate reservoir after escaping from the natural gas hydrate reservoir, in the path of the overlying sedimentary stratum, and the simulation system and related research can provide basic data and theoretical support for the evaluation of the environmental influence of the methane leakage in the natural gas hydrate decomposition.

In the specific implementation process, compared with the existing observation research on the submarine methane leakage, the leakage path simulation system 2 provides a simulation research on the migration and transformation behaviors of the methane-containing fluid decomposed and leaked by the natural gas hydrate below the submarine interface in the path of the sediment, provides a realization path for observing and simulating the leakage behaviors of the methane-containing fluid below the submarine interface, and makes up the defects that the leakage behaviors of the methane below the submarine interface are mostly limited to theoretical simulation and lack of direct experimental data support.

In the specific implementation process, when a crack-free geological channel is simulated, transparent pressure-resistant pipelines 21 filled with calcareous clay sediments as porous media are installed on an external frame according to the actual exploration requirement, and the channel form is vertical distribution; all the transparent pressure-resistant pipelines 21 are provided with a flow rate regulating device 22, a flow rate metering device 23 and a fluid form monitoring device 24, and all the devices are in circuit connection with the acquisition control system 18; placing the installed outer frame in a natural gas hydrate reservoir 1122 with the top of the outer frame in the formation and marine environment; opening all leakage pipelines as required, synchronously or sequentially adjusting the flow velocity of each passage through a flow velocity adjusting device, and simulating and researching the migration characteristic of the methane-containing fluid after the natural gas hydrate is decomposed at different leakage rates; the migration characteristic of the fluid in the pipeline is observed through the fluid form monitoring device, the leakage rate and the evolution condition of the fluid in each passage are measured through the flow rate measuring device 23, the acquisition control system 18 is used for recording and processing data and displaying images, and the condition simulation of the geological channel without the fracture type natural gas hydrate exploitation leakage is completed.

In the specific implementation process, when a crack-containing geological channel is simulated, according to the actual exploration requirement, a transparent pressure-resistant pipeline 21 filled with calcareous clay sediments as porous media is arranged on an external frame, and the channel is in a vertical and inclined combined distribution mode; all the transparent pressure-resistant pipelines 21 are provided with a flow rate regulating device 22, a flow rate metering device 23 and a fluid form monitoring device 24, and all the devices are in circuit connection with the acquisition control system 18; placing the installed outer frame in a natural gas hydrate reservoir 1122 with the top of the outer frame in the formation and marine environment; opening the vertical leakage pipeline as required, observing for a plurality of minutes, then opening the rest inclined leakage pipeline, and simulating and researching the migration and conversion behaviors of the methane-containing fluid in the passages at different leakage rates by adjusting the flow rate of each passage; the migration characteristic of the fluid in the pipeline is observed through the fluid form monitoring device 24, the leakage rate and the evolution condition of the fluid in each passage are measured through the flow rate measuring device 23, the acquisition control system 18 is used for recording and processing data and displaying images, and the condition simulation of the geological channel containing the fracture-type natural gas hydrate exploitation leakage is completed.

Example 4

More specifically, as shown in fig. 1 and 4, the cold spring ecosystem simulation system 3 includes a high pressure simulation cavity 31, in which a geological stratification is constructed, and includes an above-seabed-interface unit 32, a seabed-interface ecosystem simulation unit 33 and a below-seabed-interface unit 34 from top to bottom; the above-seabed-interface unit 32 is used for simulating the condition of the seabed water body; the seabed interface ecosystem simulation unit 33 is used for simulating a seabed interface and a deep-sea cold spring ecosystem; the subsea interface lower unit 34 is used for simulating the distribution of the seabed and the development process of the cold spring;

the high-pressure simulation cavity 31 is provided with an environmental condition control device 35 for controlling the environmental condition of the system and acquiring data;

a sampling cabin 36 is arranged on the high-pressure simulation cavity 31 and is used for placing and collecting samples of the deep-sea cold spring ecosystem;

a bottom current injection system 37 is arranged on the high-pressure simulation cavity 31, and the bottom current injection system 37 is used for injecting deep sea water into the sea bottom interface ecosystem simulation unit 33 to achieve the effect of ocean current simulation;

the sampling cabin 36 and the control end of the sea bottom flow injection system 37 are electrically connected with the environmental condition control equipment 35.

In the specific implementation process, the high-pressure simulation cavity 31 adopts a simulation structure combining spherical columns, the size of the spherical part is 8 meters in diameter, the height of the columnar part is 15 meters, the diameter of the columnar part is 5 meters, and a large enough section space of 50.24 square meters is provided for the formation and evolution of a cold spring ecosystem, and marine physical, marine chemical, marine geological and marine biological environmental conditions which are consistent with or similar to the real seabed environment are provided. Meanwhile, the sampling chamber 36 is excavated and arranged at the seabed interface to meet the development of a passage environment for cold spring fluid to escape from the seabed underlying interface.

In the specific implementation process, the simulation of the cold spring ecosystem is realized through the cold spring ecosystem simulation system 3, the unit 32 above the seabed interface, the seabed interface ecosystem simulation unit 33 and the unit 34 below the seabed interface are formed, the environmental conditions are provided for the evolution of the cold spring ecosystem, and on the basis, the primary succession and the secondary succession of the ecological cold spring system are simulated through the environmental condition control equipment 35, the sampling cabin 36 and the bottom current injection system 37, the formed environment of the system is remolded in situ, and the period of observing and researching the cold spring ecosystem in the field is effectively shortened.

In the specific implementation process, compared with the existing submarine observation and investigation means, the method can observe and research the formation and evolution of the cold spring ecosystem, can grasp key characteristic points in the development process for real-time sampling analysis, widens the research depth of the cold spring ecosystem, can save huge cost required by submarine in-situ observation and investigation research, and effectively avoids the influence of adverse conditions such as a severe sea wave environment on a research plan.

More specifically, the subsea interface lower unit 34 includes a simulation layer construction system 341 and a subsea sediment chemical zonation simulation layer 342; wherein:

the submarine sediment chemical zonation simulation layer 342 is arranged in the high-pressure simulation cavity 31, so that chemical zonation simulation of sediment below a submarine interface is realized;

the output port of the simulation layer construction system 341 is directly arranged at the bottom of the high-pressure simulation cavity 31 and is communicated with the seabed sediment chemical zonation simulation layer 342 in the high-pressure simulation cavity 31;

the leakage path simulation system 2 is connected with the bottom of the high-pressure simulation cavity 31 and discharges leaked gas into the chemical zonation simulation layer 342 of the seabed sediments;

the control end of the simulation layer construction system 341 is electrically connected to the environmental condition control device 35.

In the specific implementation process, the leakage passage simulation system 2 injects the methane gas and the methane-containing gas-liquid mixed fluid of the natural gas hydrate formation decomposition system 1 which is actually leaked into the high-pressure simulation cavity 31, and also can directly inject salt water, petroleum, gas-liquid mixed fluid and the like into the high-pressure simulation cavity 31 through the outside to simulate the development of other types of cold springs; the seabed sediment chemical banding simulation layer 342 mainly realizes chemical banding simulation in sediment below a seabed interface, simulates natural distribution of the sediment from an anaerobic oxidation zone 3421 and a secondary oxygen oxidation zone 3422 to a seabed oxygen-containing oxidation zone 3423 from bottom to top, and provides an environment for anaerobic oxidation and aerobic oxidation in a deposition layer after leaked gas or liquid is transported to the deposition layer; the simulation layer construction system 341 is used to initially construct the seafloor sediment chemical zonal simulation layer 342 within the high pressure simulation chamber 31.

More specifically, the simulation layer construction system 341 includes a sulfur-containing solution reservoir 3411, a saturated oxygen solution 3412, an injection pump 3413, a mass flow meter 3414, and a controllable valve group 3415; wherein:

the sulfur solution storage 3411 and the saturated oxygen solution 3412 are connected to the seabed sediment chemical zonation simulation layer 342 inside the high pressure simulation cavity 31 through an injection pump 3413;

the mass flow meter 3414 and the controllable valve set 3415 are arranged at the output port of the injection pump 3413;

the mass flow meter 3414 and the controllable valve set 3415 are electrically connected to the environmental condition control device 35.

More specifically, the seabed sediment chemical zoning simulation layer 342 comprises an anaerobic oxidation zone 3421, a secondary oxygen oxidation zone 3422 and an oxygen-containing oxidation zone 3423 from bottom to top; wherein:

the sulfur-containing solution reservoir 3411 is connected to the anaerobic oxidation zone 3421;

the saturated oxygen solution 3412 is connected to the sulfoxidation zone 3422.

More specifically, the environmental condition control apparatus 35 includes a second temperature sensor 351, a ring wall temperature control device 352, a second pressure sensor 353, a gas-liquid circulation device 354, a light source device 355, a metering device 356, a sampling device 357, and a processing terminal 358; wherein:

the control ends of the annular wall temperature control device 352, the gas-liquid circulation device 354, the light source device 355, the metering device 356 and the sampling device 357 are all electrically connected with the processing terminal 358;

one end of the gas-liquid circulation device 354 is provided with a through hole at the top of the high-pressure simulation cavity 31, and the other end of the gas-liquid circulation device is provided with a cavity of the high-pressure simulation cavity 31, so that the circulation of gas-liquid fluid in the unit 32 above the seabed interface is realized;

the second temperature sensors 351 are uniformly arranged in each geological layer in the high-pressure simulation cavity 31, and the signal output ends of the second temperature sensors 351 are electrically connected with the processing terminal 358;

the annular wall temperature control device 352 is wrapped on the outer wall of the high-pressure simulation cavity 31 and used for controlling the temperature in the high-pressure simulation cavity 31 to be uniform;

the second pressure sensors 353 are uniformly arranged in each geological stratification in the high-pressure simulation cavity 31; the signal output end of the pressure sensor 353 is electrically connected with the input end of the processing terminal 358;

the light source device 355 is a shadowless light source device network arranged on the submarine interface ecosystem simulation unit 33 and provides light source regulation for observing the development behavior of the cold spring fluid after escaping from the submarine interface;

the metering device 356 includes a plurality of acoustic detectors uniformly distributed outside each geological layer in the high-pressure simulation chamber 31 for monitoring the leakage rate and the leakage flux of the leaking fluid;

the sampling device 357 comprises sampling ports arranged at different positions of the above-sea-interface unit 32, the below-sea-interface ecosystem simulation unit 33 and the below-sea-interface unit 34 in the high-pressure simulation chamber 31, and the sampling device 356 is arranged on the sampling ports for collecting samples;

the processing terminal 358 is electrically connected to the sampling chamber 36 and the control end of the subsea flow injection system 37.

In the specific implementation process, the second temperature sensor 351, the annular wall temperature control device 352 and the gas-liquid circulation device 354 circulate and control the gas-liquid fluid in the unit 32 above the seabed interface, so that the temperature distribution of chemical zones of the seabed and sediments in the high-pressure simulation cavity 31 is always kept in a state similar to the seabed in-situ condition; the gas-liquid circulating device 354 mainly comprises a plurality of circulating pumps, a heat exchange unit, a flow velocity control element and the like, and is also wrapped on the annular wall temperature control device 352 outside the high-pressure simulation cavity 31, and second temperature sensors 351 are uniformly distributed at different positions in a period, so that the temperature change in the system is monitored in real time; the second pressure sensor 353 is used for monitoring the pressure change in the system in real time, the processing terminal 358 controls the simulation layer construction system 341 or the seabed flow injection system 37, and the state that the pressure environment of the seabed and sediment chemical zonation in the system is similar to the seabed in-situ condition is kept; the processing terminal 358 photographs and records the development process of the cold spring and the evolution state of the bubbles, cold spring plumes and the like in the seabed and the water body environment above the seabed interface through a flow observation element, namely an ultra-high-definition camera system and the like.

In the specific implementation process, the in-situ temperature simulation and real-time monitoring of the system are realized through the formation temperature control system 13, the second temperature sensor 351 and the annular wall temperature control device 352. The whole system is in a walk-in type low-temperature chamber, and the temperature of the simulation system is regulated and controlled through the formation temperature control system 13, the second temperature sensor 351 and the annular wall temperature control device 352.

In the specific implementation process, because the amount of seawater in the hyperbaric simulation chamber 31 is large, the seawater temperature cannot be controlled by only the annular wall temperature control device 352, at this time, the circulating pump mounted on the water-gas circulating device 354 pumps the seawater with high temperature in the hyperbaric simulation chamber 31 out of the hyperbaric simulation chamber 31, and the seawater flows back into the hyperbaric simulation chamber 31 after heat exchange and temperature reduction are realized in the heat exchange unit, so that the seawater in the hyperbaric simulation chamber 31 is cooled. By such circulation, the seawater in the hyperbaric simulation chamber 31 can be rapidly and uniformly cooled, and when the temperature is reduced to a preset value, the flow speed of the seawater can be controlled by the flow speed control element of the water-air circulation device 352 or the flow pipeline of the water-air circulation device 352 can be closed.

In the specific implementation process, the surface of the annular wall temperature control device 352 of the high-pressure simulation cabin 31 is provided with the heat preservation layer, the high-pressure simulation cabin 31 is wrapped in the middle by the two-layer structure, so that the temperature exchange between the high-pressure simulation cabin 31 and the outside is slowed down, the annular wall temperature control device 352 can realize the flow of fluid, the water in the high-pressure simulation cabin 31 is pumped out by the circulating pump, then the refrigerating unit is adopted for cooling, the cooled water is pumped back to the annular wall temperature control device 352, the heat exchange between the annular wall temperature control device 352 and the outer wall of the high-pressure simulation cabin 31 is realized equivalently, and the heat generated in the working condition state of each element in the high-pressure simulation cabin 31 can be taken out by the annular wall temperature control device 352, so that the whole high-pressure simulation cabin 31 is always in a.

In the specific implementation process, the temperature in the hyperbaric simulation chamber 31 is monitored in real time through the temperature sensors arranged at different positions, and the flow rates of the fluid in the water-gas circulation device 352 and the fluid in the annular wall temperature control device 352 are controlled according to the detection result, so that the temperature in the hyperbaric simulation chamber 31 is stably controlled.

More specifically, a seawater refrigerating unit is further installed on the water gas circulation device 354.

In the specific implementation process, the process of controlling the temperature of the hyperbaric simulation chamber 31 specifically comprises the following steps: comprises a cooling stage, a pressurizing stage and a heat preservation stage; wherein:

the cooling stage comprises:

1) injecting seawater into the high-pressure simulation cabin 31;

2) starting the seawater refrigerating unit and adjusting the flow speed control element, and pumping the seawater with high temperature in the high-pressure simulation cabin 31 out of the high-pressure simulation cabin 31 through the circulating pump;

3) after the heat exchange unit realizes heat exchange and temperature reduction, the seawater flows back to the high-pressure simulation cabin 31 to realize the temperature reduction of the seawater in the high-pressure simulation cabin 31 until the temperature of the seawater in the high-pressure simulation cabin 31 is reduced to a set value, and the temperature reduction stage is completed;

a pressurization stage:

when the temperature sensor monitors that the seawater temperature in the high-pressure simulation cabin 31 reaches a set value, gas and liquid are injected into the high-pressure simulation cabin 31, so that the pressurization in the high-pressure simulation cabin 31 is realized;

completing the pressurization stage until the pressure in the high-pressure simulation cabin 31 reaches a set value;

and (3) a heat preservation stage:

when the second temperature sensor 351 detects that the pressure in the high-pressure simulation cabin 31 reaches a set value, an insulating layer is laid on the surface of the annular wall temperature control device 352;

the refrigerating unit is started, the fluid in the annular wall temperature control device 352 circularly flows under the action of the circulating pump, and heat generated in the working condition state of each element in the high-pressure simulation cabin 31 is continuously exchanged through the coil pipe of the annular wall temperature control device 352 and the heat exchanger of the pipeline system, so that the high-pressure simulation cabin 31 is always in a preset temperature environment in the working period, and the temperature in the whole simulation cabin is uniformly distributed.

More particularly, the processing terminal 358 includes a data collector 3581, a central processor 3582, a memory 3583 and a display 3584; wherein:

the input end of the data acquisition unit 3581 is electrically connected with the output ends of the second temperature sensor 351, the second pressure sensor 353 and the metering device 356; the output end of the data acquisition unit 3581 is electrically connected with the input end of the central processing unit 3582;

the central processing unit 3582 is electrically connected with the memory 3583 to realize information interaction;

the output end of the central processing unit 3582 is electrically connected with the input end of the display 3584 and is used for displaying acquired information;

the output end of the central processing unit 3582 is electrically connected with the sampling cabin 36, the sea current injection system 37 and the control end of the environmental condition control equipment 35.

In the implementation process, the above-mentioned unit 32 of the subsea interface is mainly a seawater system simulating the bottom layer marine environment on the upper part of the subsea interface, and it is necessary to fill the system with seawater identical or similar to the actual bottom layer marine environment. The seawater of the example is artificially prepared into seawater with the salinity of about 3.4 percent according to in-situ survey data.

More specifically, the sampling chamber 36 includes an inside door 361, an outside door 362, and a pressure detector 363, a pressure balancing unit 364, a moving guide 365 and a sampler 366 disposed on the moving guide 365 disposed in the chamber; wherein:

the opening and closing state of the high-pressure simulation cavity 31 and the sampling cabin 36 is controlled through the inner cabin door 361;

controlling the open and close state of the sampling cabin 36 and the external experimental environment through the outside cabin door 362;

the pressure detector 363 is used for detecting the pressure condition in the sampling chamber 36;

the pressure balancing unit 364 is used to adjust the pressure within the sampling chamber 36;

the control ends of the inside door 361, the outside door 362, the pressure balancing unit 364, the moving guide 365 and the sampler 366 are all electrically connected with the environmental condition control device 35;

the output end of the pressure detector 363 is electrically connected with the input end of the environmental condition control equipment 35;

the sampling chamber 36 is disposed on the seabed interface ecosystem simulation unit 33, and the sampler 366 puts or collects samples into or from the seabed interface ecosystem simulation unit 33.

In a specific implementation, the sampling cabin 36 may perform the loading and collecting of the sample by moving the guide 365 to control the sampler 366, or by using a remote-controlled robot, etc.

More specifically, the sampler 366 includes a connection base, a rotation table, a clamping mechanism, and a control circuit; wherein:

the sampler 366 is disposed on the moving guide 365 through the connection base;

the rotating platform is arranged on the connecting base;

the clamping mechanism is arranged on the rotating table;

the connecting base, the rotating platform and the control end of the clamping mechanism are electrically connected with the control circuit;

the control circuit is electrically connected to the environmental condition control device 35.

More specifically, the moving rail 365 includes a rail body, a chain pushing device, and a driving motor; wherein:

the connecting base is arranged on the guide rail main body;

the bottom of the guide rail main body is arranged on the chain pushing device;

the chain pushing device is driven by the driving motor;

the drive motor control terminal is electrically connected to the environmental condition control device 35.

In the specific implementation process, the putting and collecting of the samples of the seabed interface ecosystem simulation unit 3 are realized by operating the inside door 361, the outside door 362, the pressure balance unit 364, the moving guide 365 and the sampler 366 in the sampling cabin 36, and the specific process is as follows:

when a sample is put in:

ensuring that both the inside door 361 and the outside door 362 of the sampling chamber 36 are closed, then opening the inside door 362, placing the sample to be cultured on the sampler 366, and then closing the outside door 362;

pressurizing through a pressure detector 363, after the pressure is balanced, opening an inner side cabin door 361 communicated with the high-pressure simulation cabin 31 to allow seawater to enter the sampling cabin 36, controlling a movable guide rail 365 to enable a sampler 366 to enter the high-pressure simulation cabin 31, and putting a sample to a specified position;

finally, the sampler 366 is retracted into the sampling cabin 36, and the inner side cabin door 361 communicated with the high-pressure simulation cabin 31 is closed, so that the sample is put in;

when a sample is collected:

ensuring that the inside hatch door 361 and the outside hatch door 362 of the sampling cabin 36 are both closed, then opening the inside hatch door 361 to allow seawater to enter the sampling cabin 36, controlling the movable guide rail 365 to allow the sampler 366 to enter the high-pressure simulation cabin 31 after the pressure is balanced, and grabbing a sample to be taken back;

the sampler 366 is then retracted into the sampling compartment 36, the inboard hatch 361 being closed;

the pressure is reduced by the pressure detector 363, and after the pressure is balanced, the outside port 362 is opened, and the sample is taken out to the experimental environment.

In the specific implementation process, in the action process of the sampler 366, the control circuit drives the connecting base to slide on the moving guide rail, so that the horizontal movement of the sampler 366 is realized; the control circuit drives the rotating platform which drives the clamping mechanism to rotate for 360 degrees, so that multi-angle sampling of the sampler 366 is realized; the control circuit drives the clamping mechanism to perform clamping or sending action, so that the sample is taken and clamped or put in.

In the specific implementation process, the sampler 366 can freely retract, retract and move in the sampling cabin 36 and the hyperbaric simulation cabin 31, can freely move in the hyperbaric simulation cabin 31, and has a 360-degree free sampling function for samples in the hyperbaric simulation cabin 31, and meanwhile, the sampler 366 can be carried with lighting equipment to provide a light source for the sampler 366 to enter the hyperbaric simulation cabin 1 to sample, so as to provide conditions for the sampler 65 to perform accurate sampling operation.

In the specific implementation process, the chain pushing device is driven to rotate by the driving motor, the guide rail main body hinged to the chain pushing device is pushed out or retracted, and the movable guide rail can be completely accommodated in the pressure balance cabin under the normal condition; when a sample needs to be put or collected, the movable guide rail can be pushed out into the hyperbaric simulation chamber 31, so that the sampler 366 can reach all positions on the same horizontal line, and the sample is conveniently put or collected.

In the specific implementation process, the sampling cabin 36 mainly satisfies the requirements of throwing the cold spring organisms obtained in situ from the sea bottom into the marine environment in the system, taking the cultured cold spring organisms out to simulate the system research, and realizing the functions of excavating and sampling the sediment at the sea bottom interface, correcting and adjusting the micro-topographic environment at the sea bottom, and the like.

More specifically, the pressure balancing unit 364 includes a drainage system 3641 and an exhaust system 3642 disposed within the sampling chamber 36; the control ends of the drainage system 3641 and the exhaust system 3642 are electrically connected with the environmental condition control equipment 35; the water and gas in the sampling chamber 36 are discharged through the drainage system 3641 and the exhaust system 3642, thereby controlling the pressure change in the sampling chamber 36.

In a specific implementation process, in the sampling chamber 36, the pressure balancing unit 364 performs a pressurization operation and a depressurization operation, specifically:

and (3) pressurization operation: firstly, ensuring that the inner side hatch door 361 and the outer side hatch door 362 of the sampling cabin 36 are both closed, and then opening the inner side hatch door 361, so that the gas-liquid fluid in the high-pressure simulation cavity 31 can enter the sampling cabin 36; when the pressure monitoring values in the sampling cabin 36 and the high-pressure simulation cavity 31 are consistent, the mark reaches a pressure balance state; at this time, the sampler 366 in the sampling chamber 36 can be controlled to enter the high-pressure simulation cavity 31 for operating conditions;

and (3) pressure reduction operation: firstly, closing an inside cabin door 361 of the sampling cabin 36, then opening a drainage system 3641 and an exhaust system 3642 to perform decompression operation on the sampling cabin 36, and when the pressure monitoring values in the sampling cabin 36 and the external experimental environment are consistent, marking that the pressure balance state is achieved; the outside port 362 is now open and the sample obtained from the high pressure simulation chamber 31 can be sent to the laboratory environment.

More specifically, the sea bottom flow injection system 37 comprises a plurality of nozzles, a pipeline system, an injection pump set, a regulating valve and a sea water preparation system; wherein:

the nozzle is arranged at the seabed interface ecosystem simulation unit 33 and is connected with the seawater preparation system through the pipeline system;

the injection pump group and the regulating valve are both arranged on the pipeline system;

the injection pump set, the regulating valve and the seawater preparation system are all electrically connected with the environmental condition control equipment 35;

a controller is arranged on the nozzle, and the controller is electrically connected with the environmental condition control equipment 35 and is used for controlling the range, the spraying area and the spraying direction of the nozzle.

More specifically, the seawater preparation system comprises a seawater storage tank, a heat exchange unit, a high-pressure seawater injection pump, a control valve bank and a high-pressure seawater mass flowmeter; wherein:

the heat exchange unit is arranged on the seawater storage tank and used for heat conversion of seawater;

the seawater storage tank is communicated with the pipeline system through a high-pressure seawater injection pump and a control valve group;

the high-pressure seawater mass flowmeter is arranged at the outlet of the control valve group;

the heat exchanger unit, the high-pressure seawater injection pump, the control valve group and the high-pressure seawater mass flowmeter are electrically connected with the environmental condition control unit 35.

In the specific implementation process, ocean current seawater in different sea areas has different components, different densities, different fluid viscosities and different flowing states, and the seawater preparation system prepares seawater with different components and different temperatures according to needs to simulate the requirement of generating bottom layer ocean current, so that the ocean current generated by the simulation system is closer to the real environment; the prepared ocean current is injected into the system 37 through the injection pump set, the flow of the seawater is controlled through the regulating valve, the seawater is finally injected into the high-pressure simulation cabin 31 through the pipeline system through the nozzle, and the flow field and the shape of the ocean current are controlled through the controller arranged on the nozzle, so that the ocean current simulation effect is achieved.

In the specific implementation process, the seawater storage tank is used for storing seawater, the heat exchange unit is used for controlling the temperature of the seawater in the seawater storage tank, the high-pressure seawater injection pump is used for injecting the seawater into the pipeline system, the controllable valve bank is used for controlling the flow, meanwhile, the mass flow meter is used for measuring the injection amount of the seawater, and the measurement result is transmitted to the environmental condition control unit.

In the specific implementation process, the seabed flow injection system 37 mainly simulates different seabed bottom flow environments, remodels the ocean current state around the cold spring ecosystem, and provides the ocean current environment for the material circulation and the energy flow of the cold spring ecosystem.

Example 5

More specifically, on the basis of the embodiments 1 to 4, the invention provides a natural gas hydrate decomposition methane leakage and cold spring ecological simulation method, which comprises a natural gas hydrate formation decomposition process, a gas leakage process and a cold spring ecosystem construction process, wherein:

the natural gas hydrate forming and decomposing process is to simulate the forming and decomposing process of the marine natural gas hydrate through the natural gas hydrate forming and decomposing system 1;

the gas leakage process is specifically that the migration and transformation behaviors of gas leaked from the natural gas hydrate formation decomposition system 1 into the cold spring ecological simulation system 3 are simulated and observed through the leakage passage simulation system 2;

the construction process of the cold spring ecosystem is specifically to simulate the process of cold spring development and ecosystem evolution of leaked gas through the cold spring ecological simulation system 3, so that the construction of the cold spring ecosystem is completed.

More specifically, as shown in fig. 5, the formation and decomposition process of the natural gas hydrate specifically includes the following steps:

a1: geological stratification is realized in the natural gas hydrate reservoir 1122, seawater is filled in the lower-pressure gas-liquid mixed layer 1123, silty sediment serving as a porous medium is filled in the natural gas hydrate reservoir 1122, and a calcareous clay layer is filled in the overlying sediment layer 1121;

a2: injecting pre-calculated quantitative methane gas and seawater into the natural gas hydrate reservoir 1122 through the gas-liquid injection system 15, respectively adjusting the temperature and pressure of each layer in the simulation cavity 11 of the natural gas hydrate reservoir, ensuring that the natural gas hydrate forms the required high-pressure and low-temperature environment, and forming the natural gas hydrate;

a3: when the saturation of the natural gas hydrate reaches a preset design value, opening the production well system 16 to reduce the pressure of the natural gas hydrate or decompose the natural gas hydrate in other modes;

a4: the temperature and pressure distribution and change conditions of each layer in the decomposition process of the natural gas hydrate are monitored and recorded in real time through the first temperature sensor 131 and the first pressure sensor 12; monitoring and recording the displacement settlement of the natural gas hydrate reservoir 1122 in real time through a displacement sensor 14;

a5: gas production, water production, sand production and rate are collected and recorded by the production system 17 until the natural gas hydrate synthesized in the natural gas hydrate reservoir 1122 is completely decomposed, and the simulation of the formation and decomposition process of the marine natural gas hydrate is completed.

More specifically, as shown in fig. 6, the gas leakage process includes a simulation process of a crack-free type, including the steps of:

b11: according to the actual exploration requirement, a pressure-resistant pipeline 21 filled with calcareous clay sediments as porous media is installed, and the channel form is vertical distribution;

b12: all the pressure-resistant pipelines 21 are provided with a flow rate regulating device 22, a flow rate metering device 23 and a fluid form monitoring device 24, and all the devices are in circuit connection with the acquisition control system 18;

b13: connecting the lower end of the installed leakage path simulation system 2 with a natural gas hydrate reservoir 1122, and connecting the upper end of the installed leakage path simulation system with a cold spring ecological simulation system 3;

b14: opening all pressure-resistant pipelines 21 as required, synchronously or sequentially adjusting the flow velocity of each passage through a flow velocity adjusting device 22, and simulating and researching the migration characteristic of the methane-containing fluid after the natural gas hydrate is decomposed at different leakage rates;

b15: the migration characteristic of the fluid in the pipeline is observed through the fluid form monitoring device 24, the leakage rate and the evolution condition of the fluid in each passage are measured through the flow rate measuring device 23, the acquisition control system 18 is used for recording and processing data and displaying images, and the condition simulation of the geological channel without the fracture type natural gas hydrate exploitation leakage is completed.

More specifically, as shown in fig. 7, the gas leak process includes a simulation process of a fracture-containing type, including the steps of:

b21: according to the actual exploration requirement, a pressure-resistant pipeline 21 filled with calcareous clay sediments as porous media is installed, and the channel form is vertical and inclined combined distribution;

b22: all the pressure-resistant pipelines 21 are provided with a flow rate regulating device 22, a flow rate metering device 23 and a fluid form monitoring device 24, and all the devices are in circuit connection with the acquisition control system 18;

b23: connecting the lower end of the installed leakage path simulation system 2 with a natural gas hydrate reservoir 1122, and connecting the upper end of the installed leakage path simulation system with a cold spring ecological simulation system 3;

b24: the vertical pressure-resistant pipeline 21 is firstly opened as required, the rest inclined pressure-resistant pipelines 21 are opened after observation for a plurality of minutes, the flow velocity of each passage is adjusted through the flow velocity adjusting device 22, and the migration and conversion behaviors of the methane-containing fluid in the passages at different leakage rates are simulated and researched;

b25: the migration characteristic of the fluid in the pipeline is observed through the fluid form monitoring device 24, the leakage rate and the evolution condition of the fluid in each passage are measured through the flow rate measuring device 23, the acquisition control system 18 is used for recording and processing data and displaying images, and the condition simulation of the geological channel without the fracture type natural gas hydrate exploitation leakage is completed.

More specifically, as shown in fig. 8, the construction process of the cold spring ecosystem specifically includes the following steps:

c1: filling the high-pressure simulation cavity 31 with the prepared submarine sediment chemical zonation according to actual conditions, and ensuring that the thickness, distribution, pore parameters and the like of the sediment are consistent with or similar to the real submarine conditions;

c2: respectively injecting sulfur-containing solution or saturated oxygen solution into different positions of the sediment through the simulation layer construction system 341 to form an anaerobic oxidation state or a sub-aerobic oxidation state, thereby completing the construction of the seabed interface ecosystem simulation unit 33;

c3: injecting seawater of required quantity into the high-pressure simulation cavity 31, and constructing a sea-bottom interface upper unit 32 for simulating the condition of the sea-bottom water body; meanwhile, the environmental condition control equipment 35 is controlled to ensure that physical and chemical environmental parameters in the high-pressure simulation cavity 31 meet the environmental conditions of the cold spring development of the real seabed;

c4: preparing pipeline distribution and morphological characteristics of the leakage path simulation system 2, medium filling in the pressure-resistant pipeline 21 and a flow rate adjusting device 22 of the pressure-resistant pipeline 21, opening and closing simultaneously or partially according to requirements, simulating the development behavior of the cold spring under different leakage modes, and providing a carbon source and an energy source for a seabed interface ecosystem simulation unit 33;

c5: the sediment form of the seabed interface ecosystem simulation unit 33 is adjusted through the sampling cabin 36, so that the sediment form conforms to the micro landform state of the cold spring ecosystem evolution; then cold spring organisms are put in for secondary succession culture of the cold spring ecosystem or primary succession without putting in microorganisms, and the development process of the cold spring ecosystem is observed and researched;

c6: opening a sea current injection system 37 according to actual conditions, and keeping resources inside ocean currents in the sea interface ecosystem simulation unit 33 stable; recording various development behavior information and environmental parameter index change conditions of the cold spring organisms and the ecological system in real time in the whole development process of the cold spring ecological system, and completing the simulation of the cold spring ecological system.

In the specific implementation process, the method for decomposing methane leakage by using the natural gas hydrate and simulating the cold spring ecology provided by the invention is mainly used for simulating in-situ physical, chemical and geological environmental conditions of the marine natural gas hydrate and the cold spring system by scheduling parts of the system at first. Firstly, according to actual research of geological environment parameters, a natural gas hydrate reservoir 1122 in a natural gas hydrate reservoir is filled with argillaceous silty sediments, a submerged gas-liquid mixing layer 1123 is filled with methane gas, and the natural gas hydrate reservoir 1122 and the submerged gas-liquid mixing layer 1123 are constructed in a layered mode. Injecting the required gas quantity and seawater quantity for forming the natural gas hydrate into the natural gas hydrate reservoir 1122, adjusting the temperature and pressure simulation and monitoring part of the hydrate reservoir, ensuring that the ambient temperature of the reservoir in the natural gas hydrate forming process is 8 ℃, and starting the natural gas hydrate forming process. Meanwhile, the temperature of the underlying gas-liquid mixed layer 1123 was maintained at 10 ℃ and the pressure at 14 MPa. Silt deposits are then filled in the leakage path simulation system 2 to simulate a crack-free leakage path and the individual test elements are ready for use. Then filling calcareous clay sediments in the deposition layer simulation position according to actual geological exploration data, and respectively injecting sulfate, iron/manganese-containing salt, saturated oxygen solution and the like into positions 1/3 and 3/4 away from the bottom of the deposition layer to simulate the anaerobic oxidation zone and the hypoxyoxidation zone of the deposition layer. And then, settling the sediment of the submarine interface to ensure that the submarine interface meets the conditions of development of the cold spring and evolution of a cold spring ecosystem.

Subsequently, a seawater simulation overburden seawater environment unit with required amount and required components is injected into the high-pressure simulation cavity 31, and seawater with the salinity of 3.5 percent close to the real condition is artificially configured according to the actual ocean condition. And the temperature of the unit is ensured to be 4 ℃ and the pressure is 10 MPa.

When the pressure value in the natural gas hydrate reservoir 1122 reaches 13.5MPa and the saturation of the natural gas hydrate reaches 35% of a set value, the completion of the natural gas hydrate formation stage is marked, and the decomposition work of the natural gas hydrate is started. The vertical mining well, the natural gas hydrate production system and the leakage channel system are opened, methane decomposed by natural gas hydrate enters the leakage channel system and then enters an environment with an overlying deposition layer, the methane escapes from a seabed interface to form a cold spring after the deposition layer is migrated and converted, a cold spring development process is started, the sea floor in situ obtained cold spring organisms such as mussels, tubular worms, submarine shrimps and the like can be distributed to the seabed interface through the sampling cabin 36, a secondary succession process of the cold spring ecosystem is observed, the seabed streaming system is opened at the same time, the deep sea ocean current environment is simulated, and the influence of the deep sea ocean current on the cold spring development and the evolution of the cold spring ecosystem can be researched. In the operation process of the system, the information of each environmental parameter of the natural gas hydrate reservoir simulation unit, the leakage channel system, the sedimentary layer simulation unit, the seabed interface simulation unit and the overlying seawater environment simulation unit needs to be monitored and recorded in real time.

In the specific implementation process, the system and the method for simulating the methane decomposition and the cold spring ecosystem of the natural gas hydrate simulate the decomposition and the leakage of the natural gas hydrate, combine the migration and the transformation of the leaked gas in the passing of the overlying deposition layer with the development of the cold spring ecosystem and the evolution of the cold spring ecosystem, and can simulate and remold the marine natural gas hydrate reservoir, the overlying deposition layer, the leakage channel, the seabed interface and the seawater environment system in situ, thereby realizing the research on the scientific problems of the evolution of the natural gas hydrate, the gas migration and the transformation related to the decomposition and the leakage of the natural gas hydrate, the sedimentation of the reservoir layer, the development of the cold spring ecosystem, the evolution of the cold spring ecosystem and the like.

It should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. Natural gas hydrate decomposes methane and leaks and cold spring ecological analog system, its characterized in that: the system comprises a natural gas hydrate forming and decomposing system (1), a leakage path simulation system (2) and a cold spring ecological simulation system (3); wherein:

the natural gas hydrate forming and decomposing system (1) is used for simulating the formation and decomposition of marine natural gas hydrate;

the natural gas hydrate forming and decomposing system (1) is connected with the cold spring ecological simulation system (3) through the leakage passage simulation system (2);

the leakage path simulation system (2) is used for simulating and observing the migration and transformation behaviors of gas leaked from the natural gas hydrate formation and decomposition system (1) into the cold spring ecological simulation system (3);

the cold spring ecological simulation system (3) is used for simulating the process of gas development of the cold spring and the ecological system thereof through the leakage passage simulation system (2) and realizing the simulation of the evolution of the cold spring ecological system.

2. The natural gas hydrate decomposed methane leak and cold spring ecological simulation system according to claim 1, wherein: the natural gas hydrate formation decomposition system (1) includes:

the natural gas hydrate reservoir simulation cavity (11) comprises a cavity body (111) and a plurality of simulation layers (112) arranged inside the cavity body (111);

the formation temperature control system (13) comprises a first temperature sensor (131) arranged in the simulation layer (112), a built-in heat exchanger (133) arranged in the cavity (111) and a ring wall temperature control system (132) arranged on the outer wall of the cavity (111), the first temperature sensor (131) is in signal connection with the ring wall temperature control system (132), and the built-in heat exchanger (133) is electrically connected with the ring wall temperature control system (132);

the gas-liquid injection system (15) is communicated with the bottom of the cavity (111);

a production well system (16) disposed inside the cavity (111);

the production system (17) is connected with the output end of the production well system (16), and the output end of the production system (17) is connected with the input end of the gas-liquid injection system (15);

a first pressure sensor (12) disposed in the simulation layer (112);

a displacement sensor (14) disposed in the simulation layer (112);

the acquisition control system (18) is electrically connected with the first pressure sensor (12), the annular wall temperature control system (132), the gas-liquid injection system (15), the production system (17) and the displacement sensor (14);

the leakage path simulation system (2) is arranged at the top of the cavity (11) and is electrically connected with the acquisition control system (18).

3. The natural gas hydrate decomposed methane leak and cold spring ecological simulation system according to claim 2, wherein: the simulation layer (112) comprises an overlying sedimentary layer (1121), a natural gas hydrate reservoir layer (1122) and an underlying gas-liquid mixing layer (1123) which are arranged from top to bottom in sequence; wherein:

a plurality of first pressure sensors (12) and a plurality of first temperature sensors (131) are respectively and uniformly arranged in each simulation layer (112);

the displacement sensors (14) are fixed at the bottom of the overlying sedimentary deposit (1121) at equal intervals and arranged in the natural gas hydrate reservoir (1122);

the built-in heat exchangers (133) are fixed on the top of the underlying gas-liquid mixing layer (1123) at equal intervals and are arranged in the natural gas hydrate reservoir (1122);

the production well system (16) is disposed in the natural gas hydrate reservoir (1122) with its output connected to the production system (17) through the overburden (1121).

4. The natural gas hydrate decomposed methane leak and cold spring ecological simulation system according to claim 3, wherein: the annular wall temperature control system (132) comprises a temperature controller (1321), a water bath circulating jacket (1322) and an external heat exchange unit (1323); wherein:

the water bath circulation jacket (1322) is wrapped on the outer wall of the cavity (111), and pipelines are arranged at the top and the bottom of the water bath circulation jacket (1322) and are connected with the external heat exchange unit (1323) through the pipelines; the pipeline is provided with an electromagnetic valve (1324);

the control end of the electromagnetic valve (1324), the control end of the external heat exchanger unit (1323) and the control end of the internal heat exchanger (133) are electrically connected with the output end of the temperature controller (1321);

the input end of the temperature controller (1321) is electrically connected with the output end of the first temperature sensor (131);

the temperature controller (1321) is electrically connected with the acquisition control system (18) to realize information interaction.

5. The natural gas hydrate decomposed methane leak and cold spring ecological simulation system according to claim 3, wherein: the gas-liquid injection system (15) comprises a gas injection subsystem (151) and a liquid injection subsystem (152); wherein:

the input end of the gas injection subsystem (151) is connected with the output end of the production system (17);

the control end of the gas injection subsystem (151) is electrically connected with the acquisition control system (18) to realize information interaction;

the output end of the gas injection subsystem (151) is communicated with the bottom of the cavity (111) and is used for injecting gas into the cavity (111);

the control end of the liquid injection subsystem (152) is electrically connected with the acquisition control system (18) to realize information interaction;

the output end of the liquid injection subsystem (152) is communicated with the bottom of the cavity (111) and is used for injecting liquid into the cavity.

6. The natural gas hydrate decomposed methane leak and cold spring ecological simulation system according to claim 5, wherein: the gas injection subsystem (151) comprises a high-pressure gas source (1511), an air compressor (1512), a gas booster pump (1513), a buffer container (1514), a first control valve (1515) and a gas flow meter (1516); wherein:

the output end of the high-pressure air source (1511) is connected with the input end of the buffer container (1514) through the first control valve (1515);

the air compressor (1512) is connected with the input end of the buffer container (1514) through the gas booster pump (1513);

the output end of the production system (17) is connected with the input end of the buffer container (1514) through the first control valve (1515);

the output end of the buffer container (1514) is provided with the gas flow meter (1516), and the signal output end of the gas flow meter (1516) is electrically connected with the input end of the acquisition control system (18);

the output end of the buffer container (1514) is communicated with the bottom of the cavity (111) through the first control valve (1515);

and the control ends of the air compressor (1512), the gas booster pump (1513), the first control valve (1515) and the gas flowmeter (1516) are electrically connected with the acquisition control system (18).

7. The natural gas hydrate decomposed methane leak and cold spring ecological simulation system according to claim 6, wherein: the liquid injection subsystem (152) comprises a seawater storage tank (1521), a high-pressure seawater injection pump (1522), a seawater mass flow meter (1523) and a second control valve (1524); wherein:

the output end of the seawater storage tank (1521) is connected with the input end of the high-pressure seawater injection pump (1522) through the second control valve (1524);

the seawater mass flow meter (1523) is arranged at the output end of the high-pressure seawater injection pump (1522), and the signal output end of the seawater mass flow meter (1523) is electrically connected with the input end of the acquisition control system (18);

the output end of the high-pressure seawater injection pump (1522) is communicated with the bottom of the cavity (111) through the second control valve (1524);

the control ends of the high-pressure seawater injection pump (1522), the seawater mass flow meter (1523) and the second control valve (1524) are electrically connected with the acquisition control system (18).

8. The natural gas hydrate decomposed methane leak and cold spring ecological simulation system according to claim 7, wherein: the production well system (16) comprises a horizontal production well (161), a vertical production well (162) and a third control valve (163); wherein:

the horizontal production well (161) is disposed horizontally in the natural gas hydrate reservoir (1122); the vertical production well (162) is vertically disposed in the natural gas hydrate reservoir (1122);

uniformly arranging perforation holes on the horizontal production well (161) and the vertical production well (162), wherein the perforation holes wrap a plurality of layers of sand control nets;

the output end of the horizontal production well (161) and the output end of the vertical production well (162) are connected with the input end of the production system (17) through the third control valve (163);

the control end of the third control valve (163) is electrically connected with the acquisition control system (18).

9. The natural gas hydrate decomposed methane leak and cold spring ecological simulation system according to claim 8, wherein: the production system (17) comprises a back pressure subsystem (171), a gas-liquid-solid three-phase separation device (172), a water storage tank (173), a gas collector (174) and a fourth control valve (175); wherein:

the input end of the back pressure subsystem (171) is connected with the third control valve (163), and the output end of the back pressure subsystem (171) is connected with the input end of the gas-liquid-solid three-phase separation device (172);

the liquid output end of the gas-liquid-solid three-phase separation device (172) is connected with the input end of the water storage tank (173) through the fourth control valve (175);

the gas output end of the gas-liquid-solid three-phase separation device (172) is connected with the input end of the gas collector (174) through the fourth control valve (175);

the output end of the gas collector (174) is connected with the input end of the buffer container (1514) through the first control valve (1515);

the control ends of the back pressure subsystem (171) and the fourth control valve (175) are electrically connected with the acquisition control system (18).

10. The natural gas hydrate decomposed methane leak and cold spring ecological simulation system according to claim 9, wherein: the acquisition control system (18) comprises a processor (181) and a human-computer interaction module (182), wherein the human-computer interaction module (182) is electrically connected with the processor (181) to realize information interaction;

the processor (181) is electrically connected with the pressure sensor (12), the annular wall temperature control system (132), the gas-liquid injection system (15), the production system (17), the leakage path simulation system (2) and the displacement sensor (14).

11. The natural gas hydrate decomposed methane leak and cold spring ecological simulation system according to claim 2, wherein: the leakage path simulation system (2) comprises a plurality of pressure-resistant pipelines (21), a flow rate adjusting device (22), a flow rate metering device (23) and a fluid form monitoring device (24); wherein:

one end of the pressure-resistant pipeline (21) is arranged on the cavity (111), and the other end of the pressure-resistant pipeline is arranged at the bottom of the cold spring ecological simulation system (3), so that the cavity (111) is communicated with the cold spring ecological simulation system (3);

each pressure-resistant pipeline (21) is internally provided with a flow rate regulating device (22) and a flow rate metering device (23);

the fluid form monitoring device (24) is mounted on the pressure-resistant pipe (21);

the input end of the acquisition control system (18) is electrically connected with the output ends of the flow rate metering device (23) and the fluid form monitoring device (24);

the output end of the acquisition control system (18) is electrically connected with the control ends of the flow rate regulating device (22), the flow rate metering device (23) and the fluid form monitoring device (24).

12. The natural gas hydrate decomposed methane leak and cold spring ecological simulation system according to claim 11, wherein: the pressure-resistant pipeline (21) is of a transparent structure, and the fluid form monitoring device (24) is installed on the outer wall of the transparent pressure-resistant pipeline (21).

13. The natural gas hydrate decomposed methane leak and cold spring ecological simulation system according to claim 2, wherein: the cold spring ecological simulation system (3) comprises a high-pressure simulation cavity (31), geological layering is built in the high-pressure simulation cavity (31), and the cold spring ecological simulation system comprises a submarine interface upper unit (32), a submarine interface ecological system simulation unit (33) and a submarine interface lower unit (34) from top to bottom; the above-sea-floor interface unit (32) is used for simulating the condition of the sea-floor water body; the seabed interface ecosystem simulation unit (33) is used for simulating a seabed interface and a deep sea cold spring ecosystem; the unit (34) below the seabed interface is used for simulating seabed distribution and the development process of the cold spring;

the high-pressure simulation cavity (31) is provided with an environmental condition control device (35) for controlling the environmental condition of the system and acquiring data;

a sampling cabin (36) is arranged on the high-pressure simulation cavity (31) and is used for placing and collecting samples of the deep-sea cold spring ecosystem;

the high-pressure simulation cavity (31) is provided with a bottom flow injection system (37), and the bottom flow injection system (37) is used for injecting deep sea water into the bottom interface ecosystem simulation unit (33) to achieve the effect of ocean current simulation;

the sampling cabin (36) and the control end of the sea current injection system (37) are electrically connected with the environmental condition control equipment (35).

14. The natural gas hydrate decomposed methane leak and cold spring ecological simulation system according to claim 13, wherein: the subsea interface lower unit (34) comprises a simulation layer construction system (341) and a subsea sediment chemical zonal simulation layer (342); wherein:

the submarine sediment chemical zonation simulation layer (342) is arranged in the high-pressure simulation cavity (31) to realize chemical zonation simulation of sediment below a submarine interface;

the output port of the simulation layer construction system (341) is directly arranged at the bottom of the high-pressure simulation cavity (31) and is communicated with the submarine sediment chemical zonation simulation layer (342) in the high-pressure simulation cavity (31);

the leakage path simulation system (2) is connected with the bottom of the high-pressure simulation cavity (31) and discharges leaked gas into the seabed sediment chemical zonation simulation layer (342);

the control end of the simulation layer construction system (341) is electrically connected with the environmental condition control equipment (35).

15. The natural gas hydrate decomposed methane leak and cold spring ecological simulation system according to claim 14, wherein: the simulation layer construction system (341) comprises a sulfur-containing solution storage (3411), a saturated oxygen solution (3412), an injection pump (3413), a mass flow meter (3414) and a controllable valve group (3415); wherein:

the sulfur-containing solution storage (3411) and the saturated oxygen solution (3412) are connected to the seabed sediment chemical zonation simulation layer (342) inside the high-pressure simulation cavity (31) through an injection pump (3413);

the mass flow meter (3414) and the controllable valve group (3415) are arranged at the output port of the injection pump (3413);

the mass flow meter (3414) and the controllable valve set (3415) are electrically connected with the environmental condition control equipment (35).

16. The natural gas hydrate decomposed methane leak and cold spring ecological simulation system according to claim 15, wherein: the seabed sediment chemical zoning simulation layer (342) comprises an anaerobic oxidation zone (3421), a secondary oxygen oxidation zone (3422) and an oxygen-containing oxidation zone (3423) from bottom to top; wherein:

said sulfur-containing solution reservoir (3411) is connected to said anaerobic oxidation zone (3421);

the saturated oxygen solution (3412) is connected to the sulfoxidation zone (3422).

17. The natural gas hydrate decomposed methane leak and cold spring ecological simulation system according to claim 16, wherein: the environmental condition control apparatus (35) includes a second temperature sensor (351), a ring wall temperature control device (352), a second pressure sensor (353), a gas-liquid circulation device (354), a light source device (355), a metering device (356), a sampling device (357), and a processing terminal (358); wherein:

the control ends of the annular wall temperature control device (352), the gas-liquid circulation device (354), the light source device (355), the metering device (356) and the sampling device (357) are electrically connected with the processing terminal (358);

one end of the gas-liquid circulating device (354) is provided with a through hole at the top of the high-pressure simulation cavity (31), and the other end of the gas-liquid circulating device is arranged on the cavity of the high-pressure simulation cavity (31), so that the circulation of gas-liquid fluid in the unit (32) above the seabed interface is realized;

the second temperature sensors (351) are uniformly arranged in each geological stratification in the high-pressure simulation cavity (31), and the signal output ends of the second temperature sensors (351) are electrically connected with the processing terminal (358);

the annular wall temperature control device (352) is wrapped on the outer wall of the high-pressure simulation cavity (31) and used for controlling the temperature in the high-pressure simulation cavity (31) to be uniform;

the second pressure sensors (353) are uniformly arranged in each geological stratification in the high-pressure simulation cavity (31); the signal output end of the pressure sensor (353) is electrically connected with the input end of the processing terminal (358);

the light source device (355) is a shadowless light source device network arranged on the submarine interface ecosystem simulation unit (33) and provides light source regulation for observing the development behavior of the cold spring fluid after escaping from the submarine interface;

the metering device (356) comprises a plurality of acoustic detectors uniformly arranged outside each geological stratification in the high-pressure simulation cavity (31) for monitoring the leakage rate and the leakage flux of the leaked fluid;

the sampling device (357) comprises sampling ports arranged at different positions of the above-seabed-interface unit (32), the seabed-interface ecosystem simulation unit (33) and the below-seabed-interface unit (34) in the high-pressure simulation cavity (31), and the sampling device (356) is arranged on the sampling ports and is used for collecting samples;

the processing terminal (358) is electrically connected with the sampling cabin (36) and the control end of the sea bottom flow injection system (37).

18. The natural gas hydrate decomposed methane leak and cold spring ecological simulation system according to claim 17, wherein: the processing terminal (358) comprises a data collector (3581), a central processor (3582), a memory (3583) and a display (3584); wherein:

the input end of the data acquisition unit (3581) is electrically connected with the output ends of the second temperature sensor (351), the second pressure sensor (353) and the metering device (356); the output end of the data acquisition unit (3581) is electrically connected with the input end of the central processing unit (3582);

the central processing unit (3582) is electrically connected with the memory (3583) to realize information interaction;

the output end of the central processing unit (3582) is electrically connected with the input end of the display (3584) and is used for displaying acquired information;

the output end of the central processing unit (3582) is electrically connected with the control ends of the sampling cabin (36), the sea current injection system (37) and the environmental condition control equipment (35).

19. The natural gas hydrate decomposed methane leak and cold spring ecological simulation system according to claim 13, wherein: the sampling cabin (36) comprises an inner cabin door (361), an outer cabin door (362), a pressure detector (363) arranged in the cabin, a pressure balancing unit (364), a moving guide rail (365) and a sampler (366) arranged on the moving guide rail (365); wherein:

controlling the open and close state of the high-pressure simulation cavity (31) and the sampling cabin (36) through the inner cabin door (361);

controlling the open and close state of the sampling cabin (36) and the external experimental environment through the outside cabin door (362);

the pressure detector (363) is used for detecting the pressure condition in the sampling cabin (36);

the pressure balancing unit (364) is used for adjusting the pressure in the sampling chamber (36);

the control ends of the inner side cabin door (361), the outer side cabin door (362), the pressure balancing unit (364), the moving guide rail (365) and the sampler (366) are electrically connected with the environmental condition control equipment (35);

the output end of the pressure detector (363) is electrically connected with the input end of the environmental condition control equipment (35);

the sampling cabin (36) is arranged on the seabed interface ecosystem simulation unit (33), and the sampler (366) puts or collects samples on the seabed interface ecosystem simulation unit (33).

20. The natural gas hydrate decomposed methane leak and cold spring ecological simulation system according to claim 19, wherein: the sampler (366) comprises a connecting base, a rotating table, a clamping mechanism and a control circuit; wherein:

the sampler (366) is arranged on the moving guide (365) through the connecting base;

the rotating platform is arranged on the connecting base;

the clamping mechanism is arranged on the rotating table;

the control circuit is electrically connected with the environmental condition control device (35).

21. The natural gas hydrate decomposed methane leak and cold spring ecological simulation system according to claim 20, wherein: the moving guide rail (365) comprises a guide rail main body, a chain pushing device and a driving motor; wherein:

the connecting base is arranged on the guide rail main body;

the bottom of the guide rail main body is arranged on the chain pushing device;

the chain pushing device is driven by the driving motor;

and the control end of the driving motor is electrically connected with the environmental condition control equipment (35).

22. The natural gas hydrate decomposed methane leak and cold spring ecological simulation system according to claim 19, wherein: the pressure equalization unit (364) includes a drainage system (3641) and an exhaust system (3642) disposed within the sampling compartment (36); the control ends of the drainage system (3641) and the exhaust system (3642) are electrically connected with the environmental condition control equipment (35); the water and gas in the sampling chamber (36) are discharged through the drainage system (3641) and the exhaust system (3642), so that the pressure change in the sampling chamber (36) is controlled.

23. The natural gas hydrate decomposed methane leak and cold spring ecological simulation system according to claim 13, wherein: the sea bottom flow injection system (37) comprises a plurality of nozzles, a pipeline system, an injection pump set, a regulating valve and a seawater preparation system; wherein:

the nozzle is arranged at the seabed interface ecosystem simulation unit (33) and is connected with the seawater preparation system through the pipeline system;

the injection pump set, the regulating valve and the seawater preparation system are all electrically connected with the environmental condition control equipment (35);

the nozzle is provided with a controller, and the controller is electrically connected with the environmental condition control equipment (35) and is used for controlling the range, the spraying area and the spraying direction of the nozzle.

24. The natural gas hydrate decomposed methane leak and cold spring ecological simulation system according to claim 23, wherein: the seawater preparation system comprises a seawater storage tank, a heat exchange unit, a high-pressure seawater injection pump, a control valve group and a high-pressure seawater mass flowmeter; wherein:

the heat exchange unit, the high-pressure seawater injection pump, the control valve group and the high-pressure seawater mass flowmeter are electrically connected with the environmental condition control unit (35).

25. The natural gas hydrate decomposed methane leakage and cold spring ecological simulation method is characterized in that: the method comprises a natural gas hydrate forming and decomposing process, a gas leakage process and a cold spring ecological system construction process, wherein:

the natural gas hydrate forming and decomposing process is specifically a process for simulating the formation and decomposition of marine natural gas hydrate by the natural gas hydrate forming and decomposing system (1);

the gas leakage process is specifically that the migration and transformation behaviors of gas leaked from the natural gas hydrate formation decomposition system (1) and entering the cold spring ecological simulation system (3) are simulated and observed through the leakage passage simulation system (2);

the construction process of the cold spring ecosystem is specifically to simulate the process of cold spring development and ecosystem evolution of leaked gas through a cold spring ecological simulation system (3), so that the construction of the cold spring ecosystem is completed.

26. The method for simulating methane leak and cold spring ecology by decomposing gas hydrates according to claim 25, wherein the process of forming and decomposing gas hydrates comprises the following steps:

a1: geological layering construction is realized in a natural gas hydrate reservoir (1122), seawater is filled in a lower-lying gas-liquid mixed layer (1123), silty sediment serving as a porous medium is filled in the natural gas hydrate reservoir (1122), and a calcareous clay layer is filled in an overlying sediment layer (1121);

a2: injecting pre-calculated quantitative methane gas and seawater into the natural gas hydrate reservoir (1122) through a gas-liquid injection system (15), respectively adjusting the temperature and pressure of each layer in the natural gas hydrate reservoir simulation cavity (11), ensuring that the natural gas hydrate forms the required high-pressure and low-temperature environment, and forming the natural gas hydrate;

a3: (ii) a When the saturation of the natural gas hydrate reaches a preset design value, opening a production well system (16) to reduce the pressure of the natural gas hydrate or decompose the natural gas hydrate in other modes;

a4: the temperature and pressure distribution and change conditions of each layer in the decomposition process of the natural gas hydrate are monitored and recorded in real time through a first temperature sensor (131) and a first pressure sensor (12); monitoring and recording the displacement settlement of the natural gas hydrate reservoir (1122) in real time through a displacement sensor (14);

a5: gas production, water production, sand production and speed are collected and recorded by the production system (17) until the natural gas hydrate synthesized in the natural gas hydrate reservoir (1122) is completely decomposed, and the simulation of the forming and decomposing process of the marine natural gas hydrate is completed.

27. The natural gas hydrate decomposed methane leak and cold spring ecology simulation method of claim 26, wherein the gas leak process comprises a fracture-free type simulation process comprising the steps of:

b11: according to the actual exploration requirement, a pressure-resistant pipeline (21) filled with calcareous clay sediments as porous media is installed, and the channel form is vertical distribution;

b12: all pressure-resistant pipelines (21) are provided with a flow rate adjusting device (22), a flow rate metering device (23) and a fluid form monitoring device (24), and all the devices are in circuit connection with an acquisition control system (18);

b13: connecting the lower end of the installed leakage passage simulation system (2) with a natural gas hydrate reservoir (1122) and connecting the upper end of the installed leakage passage simulation system with a cold spring ecological simulation system (3);

b14: opening all pressure-resistant pipelines (21) as required, synchronously or sequentially adjusting the flow rate of each passage through a flow rate adjusting device (22), and simulating and researching the migration characteristic of the methane-containing fluid after the natural gas hydrate is decomposed at different leakage rates;

b15: the migration characteristic of the fluid in the pipeline is observed through the fluid form monitoring device (24), the leakage rate and the evolution condition of the fluid in each passage are measured through the flow rate measuring device (23), the acquisition control system (18) is used for recording and processing data and displaying images, and the condition simulation of the geological channel without fracture type natural gas hydrate exploitation leakage is completed.

28. The natural gas hydrate decomposed methane leak and cold spring ecology simulation method of claim 27, wherein the gas leak process comprises a fracture-containing type simulation process comprising the steps of:

b21: according to the actual exploration requirement, a pressure-resistant pipeline (21) filled with calcareous clay sediments as porous media is installed, and the channel form is a vertical and inclined combined distribution combination;

b22: all pressure-resistant pipelines (21) are provided with a flow rate adjusting device (22), a flow rate metering device (23) and a fluid form monitoring device (24), and all the devices are in circuit connection with an acquisition control system (18);

b23: connecting the lower end of the installed leakage passage simulation system (2) with a natural gas hydrate reservoir (1122) and connecting the upper end of the installed leakage passage simulation system with a cold spring ecological simulation system (3);

b24: the vertical pressure-resistant pipeline (21) is firstly opened as required, the rest inclined pressure-resistant pipelines (21) are opened after a plurality of minutes of observation, the flow rate of each passage is adjusted through the flow rate adjusting device (22), and the migration and conversion behaviors of the methane-containing fluid in the passages at different leakage rates are simulated and researched;

b25: the migration characteristic of the fluid in the pipeline is observed through the fluid form monitoring device (24), the leakage rate and the evolution condition of the fluid in each passage are measured through the flow rate measuring device (23), the acquisition control system (18) is used for recording and processing data and displaying images, and the condition simulation of the geological channel without fracture type natural gas hydrate exploitation leakage is completed.

29. The method for natural gas hydrate decomposed methane leak and cold spring ecosystem simulation according to claim 28, wherein the cold spring ecosystem building process specifically comprises the following steps:

c1: according to the actual situation, the high-pressure simulation cavity (31) is filled with the sediment chemical zonation to ensure that the thickness, distribution, pore parameters and the like of the sediment are consistent with or similar to the real conditions of the seabed;

c2: respectively injecting sulfur-containing solution or saturated oxygen solution into different positions of the sediment through a simulation layer construction system (341) to form an anaerobic oxidation state or a sub-aerobic oxidation state, and completing construction of a seabed interface ecosystem simulation unit (33);

c3: injecting seawater with required quantity into the high-pressure simulation cavity (31), and constructing a unit (32) above a seabed interface for simulating the seabed water condition; meanwhile, the environmental condition control equipment (35) is controlled to ensure that physical and chemical environmental parameters in the high-pressure simulation cavity (31) conform to the real environmental conditions of the cold spring development of the seabed;

c4: preparing pipeline distribution and morphological characteristics of a leakage path simulation system (2), medium filling in a pressure-resistant pipeline (21) and a flow rate adjusting device (22) of the pressure-resistant pipeline (21), opening and closing simultaneously or partially according to requirements, simulating development behaviors of cold springs in different leakage modes, and providing a carbon source and an energy source for a seabed interface ecosystem simulation unit (33);

c5: the sediment form of a seabed interface ecosystem simulation unit (33) is adjusted through a sampling cabin (36) to enable the sediment form to conform to the micro landform state of the evolution of a cold spring ecosystem; then putting in cold spring organisms, carrying out secondary succession culture on the cold spring ecosystem, and observing and researching the development process of the cold spring ecosystem;

c6: opening a sea current injection system (37) according to the actual situation, and keeping the resources inside the ocean current in the sea interface ecosystem simulation unit (33) stable; recording various development behavior information and environmental parameter index change conditions of the cold spring organisms and the ecological system in real time in the whole development process of the cold spring ecological system, and completing the simulation of the cold spring ecological system.

30. The method for ecological simulation of natural gas hydrate decomposed methane leakage and cold spring according to claim 29, wherein the operation process of the sampling cabin (36) is as follows:

when a sample is put in:

ensuring that the inside hatch (361) and the outside hatch (362) of the sampling cabin (36) are closed, then opening the inside hatch (362), placing the sample to be cultured on the sampler (366), and then closing the outside hatch (362);

pressurizing by a pressure detector (363), opening an inner side cabin door (361) communicated with the high-pressure simulation cabin (31) after pressure is balanced, allowing seawater to enter a sampling cabin (36), controlling a movable guide rail (365) to enable a sampler (366) to enter the high-pressure simulation cabin (31), and putting a sample to a specified position;

finally, the sampler (366) is retracted into the sampling cabin (36), and an inner side cabin door (361) communicated with the high-pressure simulation cabin (31) is closed to finish the throwing of the sample;

when a sample is collected:

ensuring that the inner side cabin door (361) and the outer side cabin door (362) of the sampling cabin (36) are closed, then opening the inner side cabin door (361) to allow seawater to enter the sampling cabin (36), controlling the movable guide rail (365) to enable the sampler (366) to enter the high-pressure simulation cabin (31) after the pressure is balanced, and grabbing a sample to be retrieved;

subsequently retracting the sampler (366) into the sampling compartment (36) and closing the inside hatch (361);

the pressure is reduced through a pressure detector (363), after the pressure is balanced, an outer side cabin door (362) is opened, and a sample is taken out to the experimental environment.

31. The natural gas hydrate decomposed methane leak and cold spring ecological simulation method according to claim 30, wherein the pressurization operation and the depressurization operation are performed in the sampling chamber (36) through a pressure balancing unit (364), and the process is specifically as follows:

and (3) pressurization operation: firstly, ensuring that an inner side cabin door (361) and an outer side cabin door (362) of the sampling cabin (36) are closed, and then opening the inner side cabin door (361), so that gas-liquid fluid in the high-pressure simulation cavity (31) can enter the sampling cabin (36); when the pressure monitoring values in the sampling cabin (36) and the high-pressure simulation cavity (31) are consistent, the mark reaches a pressure balance state; at the moment, a sampler (366) in the sampling cabin (36) can be controlled to enter the high-pressure simulation cavity (31) for operating the working condition;

and (3) pressure reduction operation: firstly, closing an inside cabin door (361) of a sampling cabin (36), then opening a drainage system (3641) and an exhaust system (3642) to perform decompression operation on the sampling cabin (36), and when pressure monitoring values in the sampling cabin (36) and the external experimental environment are consistent, marking the sampling cabin to reach a pressure balance state; the outside port (362) is now open and the sample obtained from the high pressure simulation chamber (31) can be sent to the laboratory environment.