A device and method for continuous isotope monitoring of hydrate formation and decomposition process

Abstract

This disclosure provides a device and method for continuous isotope monitoring during the hydrate formation and decomposition process, applicable to the field of natural gas hydrate development. The device comprises: a high-pressure reaction system comprising a rubber cylinder, a stainless steel housing, a liquid inlet valve, and a hand pump; a fluid control and automatic sampling system comprising a vacuum pump, an electric backpressure valve, a gas extraction line, a one-way valve, an inlet valve, a vent line, and a high-pressure gas cylinder; a continuous analysis and monitoring system comprising a first temperature sensor, a second temperature sensor, a first pressure sensor, a second pressure sensor, a third pressure sensor, and an isotope mass spectrometer; a temperature-controlled circulation system comprising a water bath circulation pump and a water bath; and a data acquisition and control system comprising an online computer, a programmable logic controller (PLC), and a flow meter. This device enables online continuous monitoring of isotope composition during the natural gas hydrate phase transition process. Combined with dynamic acquisition of parameters such as temperature and pressure, this improves the accuracy and continuity of experimental monitoring.

Description

Technical Field

[0001] The present disclosure relates to the field of natural gas hydrate development, and in particular to a device and method for continuous isotope monitoring of hydrate formation and decomposition processes. Background Art

[0002] Natural gas hydrates are cage-like crystalline compounds formed by hydrogen bonding between water molecules and gas molecules (such as methane) under low-temperature and high-pressure conditions. They are widely distributed in deep-sea sediments and permafrost areas on land. They have extremely high energy density and hold great potential as a clean energy source.

[0003] However, the stability of natural gas hydrates is extremely sensitive to changes in temperature and pressure, and they are prone to decomposition under disturbed conditions, releasing large amounts of methane. As a potent greenhouse gas, methane's greenhouse effect is far greater than that of carbon dioxide. Therefore, large-scale decomposition of natural gas hydrates could become a potential climate risk, further exacerbating global warming. Therefore, in-depth research on the formation and decomposition processes of natural gas hydrates is of great significance for both energy development and environmental protection.

[0004] Stable isotope technology has become an important means to study the formation and decomposition mechanism of hydrates due to its high sensitivity in identifying the source of materials and tracing the transformation path. In particular, carbon isotopes (δ 13 C), hydrogen isotopes (δD), and oxygen isotopes (δ 18 O) can reflect the material migration mechanism during the gas-water phase transition process and help evaluate the hydrate reserves and formation environment.

[0005] Currently, laboratory research mostly uses static simulation methods, where water and excess methane are injected into a reactor under set temperature and pressure conditions to generate hydrates. The generated free gas or the gas released by hydrate decomposition is then intermittently sampled and analyzed for isotopes offline. While this method is simple to operate, it has the following drawbacks:

[0006] (1) The sampling method is mainly intermittent offline, which cannot achieve real-time monitoring of the entire process and is difficult to capture the rapid isotope evolution behavior during the hydrate phase transition;

[0007] (2) Most experimental systems are single-pressure simulations, which makes it difficult to truly reproduce the multiple pressure coupling conditions such as water pressure, gas pressure, and confining pressure in real hydrate reservoirs, and the simulation accuracy is limited;

[0008] (3) Most experiments focus on the early or late stages of hydrate formation, and lack a systematic study of the continuous changes in isotopes during the entire formation-decomposition process. Summary of the Invention

[0009] The present disclosure provides a device and method for continuous isotope monitoring of a hydrate formation-decomposition process, to at least solve the above technical problems existing in the prior art.

[0010] According to a first aspect of the present disclosure, a device for continuous isotope monitoring of a hydrate formation-decomposition process is provided, the device comprising:

[0011] The high-pressure reaction system includes a rubber cylinder 1, a stainless steel shell 2, a liquid inlet valve 3 and a hand pump 4, which are used to provide a pressure environment for the formation and decomposition of natural gas hydrates;

[0012] The fluid control and automatic sampling system includes a vacuum pump 9, an electric back pressure valve 14, an air extraction line 15, a one-way valve 16, an air inlet valve 20, a ventilation line 21 and a high-pressure gas cylinder 22, which are used to inject the reaction gas into the rubber cylinder 1 and control the automatic sampling of the gas;

[0013] The continuous analysis and monitoring system includes a first temperature sensor 5, a second temperature sensor 11, a first pressure sensor 6, a second pressure sensor 12, a third pressure sensor 13 and an isotope mass spectrometer 17, which is used to monitor the temperature value, pressure value and gas isotope composition in real time;

[0014] The temperature control circulation system includes a water bath circulation pump 7 and a water bath tank 18, which are used to provide a temperature environment for the formation and decomposition of natural gas hydrates;

[0015] The data acquisition and control system includes an online computer 8, a programmable logic controller PLC unit 10 and a flow meter 19, which are used for real-time acquisition of experimental data, intelligent control of environmental parameters and result analysis.

[0016] In one embodiment, in the high pressure reaction system:

[0017] The rubber tube 1 is filled with a water sample or a rock core to form a reaction cavity;

[0018] The stainless steel shell 2 covers the rubber tube 1 to form a confined pressure chamber;

[0019] The hand pump 4 is connected to the confining pressure chamber through the liquid inlet valve 3 and is used to inject water into the confining pressure chamber to increase pressure.

[0020] In one embodiment, in the fluid control and automatic sampling system:

[0021] The high-pressure gas cylinder 22 is connected to the inlet end of the rubber cylinder 1 through the ventilation pipe 21 and the air inlet valve 20, and is used to inject the reaction gas into the rubber cylinder 1;

[0022] The inlet end of the gas extraction line 15 is connected to the outlet end of the rubber tube 1, and the outlet end of the gas extraction line is connected to the isotope mass spectrometer 17 through the electric back pressure valve 14 and the one-way valve 16 in sequence, for automatic sampling and providing the gas to the isotope mass spectrometer 17;

[0023] The vacuum pump 9 is connected to the rubber tube 1 through the air extraction line 15 and the electric back pressure valve 14 to evacuate the reaction chamber.

[0024] In one embodiment, in the continuous analysis and monitoring system:

[0025] The first temperature sensor 5 and the first pressure sensor 6 are connected to the inside of the rubber tube 1 and are used to detect the first temperature value and the first pressure value of the reaction chamber;

[0026] The second temperature sensor 11 and the second pressure sensor 12 are connected to the confining pressure chamber, and are used to detect a second temperature value and a second pressure value of the confining pressure chamber;

[0027] The third pressure sensor 13 is disposed in the ventilation line 21 and is used to detect a third pressure value in the ventilation line 21 .

[0028] In one embodiment, in the temperature control circulation system:

[0029] The water bath 18 covers the stainless steel housing 2 ; the water bath circulation pump 7 and the water bath 18 form a closed loop for controlling the temperature of the confining pressure chamber.

[0030] In one embodiment, in the data acquisition and control system:

[0031] The flow meter 19 is connected in series to the ventilation pipe 21, and is used to measure the gas flow rate in the ventilation pipe 21 and transmit the gas flow rate data to the online computer 8; it is also used to control the gas flow rate according to the first pressure value of the first pressure sensor 6;

[0032] The online computer 8 is in communication connection with the output ends of the first temperature sensor 5, the second temperature sensor 11, the first pressure sensor 6, the second pressure sensor 12, the third pressure sensor 13 and the isotope mass spectrometer 17, and is used to obtain the first temperature value, the second temperature value, the first pressure value, the second pressure value, the third pressure value, the flow value and the isotope detection result;

[0033] The PLC unit 10 is electrically connected to and controls the electric back pressure valve 14 and the vacuum pump 9;

[0034] The PLC unit 10 exchanges data with the online computer 8 .

[0035] According to a second aspect of the present disclosure, a method for a continuous isotope monitoring device for hydrate formation and decomposition is provided, characterized in that the method is applied to the above-mentioned continuous isotope monitoring device for hydrate formation and decomposition, and the method comprises:

[0036] Perform the following monitoring steps in target mode:

[0037] Injecting a sample into the rubber tube and sealing the rubber tube and the stainless steel shell; the sample is a core sample or a water sample of a set volume;

[0038] Close the electric back pressure valve and start the vacuum pump to evacuate the gas extraction line;

[0039] Start the water bath circulation pump and set the water bath temperature to the target temperature;

[0040] Use a hand pump to pass water into the confining pressure cavity between the rubber cylinder and the stainless steel shell through the liquid inlet valve to establish the target confining pressure condition;

[0041] Open the air inlet valve and inject the reaction gas into the rubber cylinder through the ventilation pipe connected to the high-pressure gas cylinder;

[0042] When the gas pressure in the reaction chamber meets the conditions for natural gas hydrate formation, the gas inlet valve is closed to allow natural gas hydrate to form spontaneously;

[0043] The electric back pressure valve is controlled by the PLC unit to release the gas, which then enters the isotope mass spectrometer through a one-way valve for real-time isotope monitoring and analysis.

[0044] After each round of sampling, the PLC unit controls the closing of the electric back pressure valve and restarts the vacuum pump to evacuate the gas pipeline to remove residual gas.

[0045] Induce the decomposition of natural gas hydrates, and allow the gases released during the decomposition process to enter the isotope mass spectrometer for real-time isotope monitoring and analysis.

[0046] In one embodiment, the target mode is a single variable control mode, including:

[0047] fixing all parameters except a target variable, wherein the target variable is one of temperature, pressure, salinity, gas composition, or deposition medium;

[0048] The experiment was repeated and hydrate formation and decomposition experiments were performed by changing the target variable value.

[0049] In one embodiment, the target pattern is a periodic perturbation pattern, including:

[0050] The electric back pressure valve is controlled by a PLC unit to automatically and cyclically adjust the pressure of the reaction chamber to decrease in a step-by-step manner according to a preset disturbance period; or the temperature of the reaction chamber is automatically and cyclically adjusted by a water bath circulation pump according to a preset disturbance period;

[0051] After each preset disturbance cycle is completed, the vacuum pump is controlled to evacuate the gas pipeline.

[0052] In one embodiment, the target mode is a multivariable coupling mode, including:

[0053] Synchronously regulating at least two correlated variables, including but not limited to temperature, pressure, gas component type, salinity, and deposition medium type;

[0054] The experiment was repeated and hydrate formation and decomposition experiments were performed by adjusting the combination of the associated variables.

[0055] The disclosed device and method for continuous isotope monitoring of the hydrate formation-decomposition process include a high-pressure reaction system using a nested confining pressure structure constructed of a rubber tube and a stainless steel shell. The liquid inlet valve and hand pump are only used to inject water into the confining pressure chamber to increase pressure, simulating formation confining pressure conditions. The fluid control system establishes independent gas injection and sampling channels through the coordinated design of a vacuum pump, an electric back-pressure valve, and a one-way valve, completely avoiding the risk of cross-contamination. The multi-sensor network (including temperature and pressure sensors) deployed in the monitoring system is linked to an isotope mass spectrometer to synchronously track temperature and pressure changes and gas isotope composition during the phase change process. The temperature control system utilizes the encapsulated heat conduction structure of the water bath in combination with real-time temperature feedback to achieve uniform control of the temperature field, meeting the temperature sensitivity requirements of the hydrate phase change. The data system is based on the intelligent architecture of PLC units and online computers to achieve coordinated control of experimental equipment and multi-source data fusion analysis, supporting automated experimental mode operation.

[0056] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present disclosure, nor is it intended to limit the scope of the present disclosure. Other features of the present disclosure will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] The above and other objects, features and advantages of the exemplary embodiments of the present disclosure will become readily understood by reading the detailed description below with reference to the accompanying drawings, in which several embodiments of the present disclosure are shown by way of example and not limitation, wherein:

[0058] In the drawings, the same or corresponding reference numerals denote the same or corresponding parts.

[0059] Figure 1 A schematic diagram of the structure of a device for continuous isotope monitoring of hydrate formation and decomposition process according to an embodiment of the present disclosure is shown;

[0060] Figure 2 A schematic diagram of the implementation process of the method for continuous isotope monitoring of the hydrate formation-decomposition process according to an embodiment of the present disclosure is shown;

[0061] Figure 3 A schematic diagram showing flow rate changes during the gas injection process according to an embodiment of the present disclosure is shown;

[0062] Figure 4 A schematic diagram showing pressure changes during the gas injection process according to an embodiment of the present disclosure is shown;

[0063] Figure 5 A schematic diagram showing temperature changes during the spontaneous generation of hydrates according to an embodiment of the present disclosure is shown;

[0064] Figure 6 A schematic diagram showing pressure changes during the spontaneous generation of hydrates according to an embodiment of the present disclosure is shown;

[0065] Figure 7 A schematic diagram showing temperature changes during the hydrate decomposition process according to an embodiment of the present disclosure is shown;

[0066] Figure 8 A schematic diagram showing pressure changes during the hydrate decomposition process according to an embodiment of the present disclosure is shown;

[0067] Figure 9 A schematic diagram of carbon isotope variation according to an embodiment of the present disclosure is shown;

[0068] Figure 10 A schematic diagram of temperature variation of periodic disturbance according to an embodiment of the present disclosure is shown;

[0069] Figure 11 A schematic diagram of pressure changes caused by periodic disturbances according to an embodiment of the present disclosure is shown.

[0070] Description of reference numerals:

[0071] 1. Rubber cylinder; 2. Stainless steel shell; 3. Liquid inlet valve; 4. Hand pump; 5. First temperature sensor; 6. First pressure sensor; 7. Water bath circulation pump; 8. Online computer; 9. Vacuum pump; 10. PLC unit; 11. Second temperature sensor; 12. Second pressure sensor; 13. Third pressure sensor; 14. Electric back pressure valve; 15. Gas extraction line; 16. One-way valve; 17. Isotope mass spectrometer; 18. Water bath; 19. Flow meter; 20. Gas inlet valve; 21. Ventilation line; 22. High-pressure gas cylinder. DETAILED DESCRIPTION

[0072] To make the purposes, features, and advantages of the present disclosure more apparent and understandable, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present disclosure, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present disclosure without creative work shall fall within the scope of protection of the present disclosure.

[0073] The present disclosure provides a device for continuous isotope monitoring of hydrate formation-decomposition process, such as Figure 1 As shown, the device includes:

[0074] The high-pressure reaction system includes a rubber cylinder 1, a stainless steel shell 2, a liquid inlet valve 3 and a hand pump 4, and is used to provide a pressure environment for the formation and decomposition of natural gas hydrates.

[0075] In this example, a rubber cylinder 1 serves as the core reaction chamber to hold the sample. A stainless steel shell 2 encases the cylinder 1, forming a sealed confining pressure chamber. A hand pump 4 injects water into the confining pressure chamber to simulate formation pressure. A liquid inlet valve 3, located at the top of the rubber cylinder, enables manual injection. This design replicates the multi-pressure coupled reservoir environment through the physical confining pressure chamber structure, ensuring the safety of high-pressure experiments.

[0076] The fluid control and automatic sampling system includes a vacuum pump 9, an electric back pressure valve 14, an air extraction line 15, a one-way valve 16, an air inlet valve 20, a ventilation line 21 and a high-pressure gas cylinder 22, which are used to inject reaction gas into the rubber cylinder 1 and control the automatic sampling of the gas.

[0077] In this example, the gas injection path is from high-pressure gas cylinder 22 to ventilation line 21, inlet valve 20, and inlet of rubber cylinder 1. The sampling path is from outlet of rubber cylinder 1 to gas extraction line 15, electric backpressure valve 14, one-way valve 16, and isotope mass spectrometer 17. A vacuum pump 9 is connected to gas extraction line 15 to perform vacuuming. This separate path design physically isolates gas injection and sampling, preventing cross-contamination of gas components.

[0078] The continuous analysis and monitoring system includes a first temperature sensor 5, a second temperature sensor 11, a first pressure sensor 6, a second pressure sensor 12, a third pressure sensor 13 and an isotope mass spectrometer 17, which is used to monitor temperature, pressure and gas isotope composition in real time.

[0079] In this example, first temperature sensor 5 and first pressure sensor 6 are directly connected to the interior of rubber cylinder 1 to monitor the temperature and pressure of the reaction environment. Second temperature sensor 11 and second pressure sensor 12 are located in the confining pressure chamber to monitor pressure transmission. Third pressure sensor 13 is located in ventilation line 21 to monitor inlet pressure. Isotope mass spectrometer 17 receives gas through one-way valve 16 for real-time analysis. This multi-position sensor network, combined with real-time online isotope mass spectrometry, enables simultaneous tracking of all parameters of the phase transition process.

[0080] The temperature control circulation system includes a water bath circulation pump 7 and a water bath tank 18, which are used to provide a temperature environment for the formation and decomposition of natural gas hydrates.

[0081] In this example, a water bath 18 encases a stainless steel housing 2, forming a direct heat exchange interface. A water bath circulation pump 7 drives the fluid in a closed loop, which, in conjunction with feedback from a second temperature sensor 11, enables precise temperature control. This encapsulated heat conduction structure ensures a uniform temperature distribution, meeting the stringent temperature sensitivity requirements of natural gas hydrate phase transitions.

[0082] The data acquisition and control system includes an online computer 8, a programmable logic controller PLC unit 10 and a flow meter 19, which are used for real-time acquisition of experimental data, intelligent control of environmental parameters and result analysis.

[0083] In this example, an online computer 8 receives signals from all sensors and an isotope mass spectrometer 17. A PLC unit 10 controls the opening and closing cycles of the electric backpressure valve 14 and the timing of the start and stop of the vacuum pump 9. A flow meter 19 adjusts the gas velocity based on the pressure in the reaction chamber. The online computer 8 integrates the data streams and executes the three experimental mode programs. This architecture implements closed-loop control based on multi-source data fusion, ensuring the timing accuracy of continuous sampling.

[0084] The present disclosure provides a continuous isotope monitoring device for the hydrate formation-decomposition process, including a high-pressure reaction system comprising a nested confining pressure structure constructed of a rubber tube and a stainless steel shell, a hand-cranked pump for simulating formation pressure, and a liquid inlet valve for forming a safe and stable reaction environment. A fluid control system establishes independent gas injection and sampling channels through the coordinated design of a vacuum pump, an electric back-pressure valve, and a one-way valve, thereby completely avoiding the risk of cross-contamination. A multi-sensor network (including temperature and pressure sensors) deployed in the monitoring system is linked to an isotope mass spectrometer to synchronously track temperature and pressure changes and gas isotope composition during phase change. A temperature control system utilizes the encapsulated heat conduction structure of a water bath in conjunction with real-time temperature feedback to achieve uniform control of the temperature field, thereby meeting the temperature sensitivity requirements of hydrate phase change. A data system, based on the intelligent architecture of a PLC unit and an online computer, enables coordinated control of experimental equipment and multi-source data fusion analysis, supporting automated experimental mode operation.

[0085] In one example, in the high-pressure reaction system: the rubber tube 1 is filled with a water sample or a rock core to form a reaction chamber; the stainless steel shell 2 covers the rubber tube 1 to form a confined pressure chamber; the hand pump 4 is connected to the confined pressure chamber through the liquid inlet valve 3, and is used to inject water into the confined pressure chamber to increase pressure.

[0086] In this example, the rubber cylinder 1 serves as the core reaction container, directly accommodating water samples or core samples, such as 10 mL of deionized water or saturated water cores, to form a closed reaction chamber; the stainless steel shell 2 tightly wraps the rubber cylinder 1, and the cavity formed between the two is the confining pressure chamber, which is simulated by injecting water into the cavity and pressurizing it to simulate the formation confining pressure environment; the hand pump 4 is connected to the water injection port of the confining pressure chamber through a pipeline, and the liquid inlet valve 3 is actually located at the top of the rubber cylinder and is independently used to inject liquid samples.

[0087] In one example, in the fluid control and automatic sampling system: the high-pressure gas cylinder 22 is connected to the inlet end of the rubber cylinder 1 through the ventilation pipe 21 and the air inlet valve 20, for injecting reaction gas into the rubber cylinder 1; the inlet end of the gas extraction line 15 is connected to the outlet end of the rubber cylinder 1, and the outlet end of the gas extraction line is connected to the isotope mass spectrometer 17 through the electric back pressure valve 14 and the one-way valve 16 in sequence, for automatic sampling and providing to the isotope mass spectrometer 17; the vacuum pump 9 is connected to the rubber cylinder 1 through the gas extraction line 15 and the electric back pressure valve 14, for evacuating the reaction chamber.

[0088] In this example, a high-pressure gas cylinder 22 is connected to an air inlet valve 20 via a vent line 21 and ultimately to the top inlet of the rubber tube 1. This path is used to inject gas, such as methane, into the reaction chamber, and the air inlet rate is controlled by a flow meter 19.

[0089] The inlet end of the gas extraction line 15 is connected to the outlet end at the top of the rubber tube 1 and is physically isolated from the gas inlet; the gas flows through the electric back pressure valve 14 and the one-way valve 16 for controlling the release rate in sequence to prevent backflow, and finally enters the isotope mass spectrometer 17 for real-time analysis.

[0090] The vacuum pump 9 is directly connected to the gas extraction line 15 , and vacuumizes the reaction chamber in the rubber tube 1 by sucking the line.

[0091] In one example, in the continuous analysis and monitoring system: the first temperature sensor 5 and the first pressure sensor 6 are connected to the inside of the rubber tube 1, for detecting the first temperature value and the first pressure value of the reaction chamber; the second temperature sensor 11 and the second pressure sensor 12 are connected to the confined pressure chamber, for detecting the second temperature value and the second pressure value of the confined pressure chamber; the third pressure sensor 13 is arranged in the ventilation line 21, for detecting the third pressure value in the ventilation line 21.

[0092] In this example, a first temperature sensor 5 and a first pressure sensor 6 are connected to the reaction chamber inside the rubber tube 1, capturing temperature and pressure data during the reaction in real time, namely, the first temperature value and the first pressure value. A second temperature sensor 11 and a second pressure sensor 12 are arranged in the confined pressure chamber space between the stainless steel shell 2 and the rubber tube 1, continuously monitoring the confined pressure environment state that simulates the formation stress, that is, detecting and obtaining the second temperature value and the second pressure value of the confined pressure chamber. A third pressure sensor 13 is embedded in the ventilation line 21, dynamically feedbacking gas injection pressure fluctuations. By synchronously covering the reaction core area, the pressure transmission interface, and the gas source input channel through a multi-level sensing architecture, a multi-dimensional parameter monitoring network for the hydrate formation and decomposition process is fully constructed, providing a global environmental perception foundation for closed-loop control.

[0093] In one example, in the temperature control circulation system: the water bath 18 covers the stainless steel shell 2; the water bath circulation pump 7 and the water bath 18 form a closed loop for controlling the temperature of the confining pressure chamber.

[0094] In this example, a water bath 18 completely covers the outer surface of the stainless steel housing 2 through physical coating, forming a direct heat conduction interface. A water bath circulation pump 7 drives a constant-temperature fluid through a closed-loop flow between the water bath 18 and the external circulation equipment, precisely regulating the temperature of the confining pressure chamber through continuous heat exchange. By immersing the entire reaction system in a uniform temperature field, coupled with real-time feedback from a second temperature sensor 11, the effects of local temperature gradients on the hydrate phase transition process are eliminated, ensuring the stability of low-temperature, high-pressure experimental conditions.

[0095] In one example, in the data acquisition and control system: the flow meter 19 is connected in series in the ventilation line 21, for measuring the gas flow rate in the ventilation line 21 and transmitting the gas flow rate data to the online computer 8; it is also used to control the gas flow rate according to the first pressure value of the first pressure sensor 6; the online computer 8 is connected to the output end of the first temperature sensor 5, the second temperature sensor 11, the first pressure sensor 6, the second pressure sensor 12, the third pressure sensor 13 and the isotope mass spectrometer 17 for communication, for obtaining the first temperature value, the second temperature value, the first pressure value, the second pressure value, the third pressure value, the flow value and the isotope detection result; the PLC unit 10 is electrically connected to and controls the electric back pressure valve 14 and the vacuum pump 9; the PLC unit 10 exchanges data with the online computer 8.

[0096] In this example, the flow meter 19 is integrated in series in the ventilation line 21 to monitor the gas injection rate in real time, and transmit the gas flow rate data to the online computer 8, and also controls the gas flow rate injected into the reaction chamber according to the first pressure value of the first pressure sensor 6.

[0097] The online computer 8 receives the first temperature value and the first pressure value from the reaction chamber, the second temperature value and the second pressure value from the confining pressure chamber, the third pressure value from the ventilation line 21 and the isotope result output by the isotope mass spectrometer 17, forming a global parameter synchronous acquisition network.

[0098] The PLC unit 10 directly controls the opening and closing timing of the electric back pressure valve 14 and the working cycle of the vacuum pump 9.

[0099] Furthermore, the online computer 8 communicates bidirectionally with the PLC unit 10, integrating and analyzing data streams and issuing control strategies for the three experimental modes. Multi-source data fusion drives dynamic closed-loop adjustment of the actuators, enabling precise control of environmental parameters during the hydrate phase transition process and coordinated continuous sampling timing, ensuring the stability and reliability of online isotope monitoring.

[0100] The present disclosure also provides a method for continuous isotope monitoring of hydrate formation-decomposition process, which is applied to the above-mentioned device for continuous isotope monitoring of hydrate formation-decomposition process, such as Figure 2 As shown, the method includes:

[0101] Perform the following monitoring steps in target mode:

[0102] Step 201: injecting a sample into the rubber tube and sealing the rubber tube and the stainless steel shell; the sample is a core sample or a water sample of a set volume.

[0103] In this example, a core sample or a set volume of water sample (such as deionized water or saline simulated pore water) is injected into the rubber cylinder, and then the cavity formed by the rubber cylinder and the stainless steel shell is sealed to ensure safe isolation of the high-pressure environment and prevent experimental leakage.

[0104] Step 202: Close the electric back pressure valve and start the vacuum pump to evacuate the air extraction line.

[0105] In this example, after closing the electric back pressure valve, the vacuum pump is started to evacuate the gas extraction pipeline (for example, for ≥5 minutes) to completely remove the residual gas and eliminate its interference with the isotope detection results.

[0106] Step 203: Start the water bath circulation pump to set the water bath temperature to the target temperature.

[0107] In this example, the water bath circulation pump is started, and the temperature is precisely set to the target value (e.g., 2°C ± 0.1°C). Real-time feedback control is performed through the temperature sensor to maintain a stable temperature range for hydrate formation / decomposition.

[0108] Step 204: Use a hand pump to pass water into the confining pressure cavity between the rubber tube and the stainless steel shell through the liquid inlet valve to establish the target confining pressure condition.

[0109] In this example, a hand pump is used to inject water into the confining pressure chamber to pressurize it to the target confining pressure (e.g., 8–12 MPa) to simulate the actual reservoir pressure. A second pressure sensor monitors the pressure in real time and ensures that it remains constant.

[0110] Step 205: Open the air inlet valve and inject the reaction gas into the rubber tube through the high-pressure gas cylinder connected to the ventilation pipe.

[0111] In this example, the intake valve is opened, and the reaction gas (such as methane) in the high-pressure gas cylinder is injected into the rubber cylinder through the ventilation pipe. The flow meter is linked to the third pressure sensor to dynamically adjust the intake rate (20-80mL / min).

[0112] Step 206: When the gas pressure in the reaction chamber meets the conditions for natural gas hydrate formation, the gas inlet valve is closed to allow natural gas hydrate to form spontaneously.

[0113] In this example, when the pressure in the reaction chamber reaches the hydrate stability zone (e.g., 6 MPa), the air inlet valve is closed, and the reaction system spontaneously forms hydrates under constant temperature conditions, with the corresponding pressure sensor continuously recording the pressure changes.

[0114] Step 207: The electric back pressure valve is controlled by the PLC unit to release the gas, and the gas enters the isotope mass spectrometer through the one-way valve for real-time isotope monitoring and analysis.

[0115] In this example, the PLC unit controls the electric back pressure valve to open periodically (5–10 seconds / cycle) according to the preset program. The released gas enters the isotope mass spectrometer through the one-way valve and analyzes the δ 13 C, δD and other isotopic compositions.

[0116] Step 208: After each round of sampling is completed, the PLC unit controls the closing of the electric back pressure valve and restarts the vacuum pump to evacuate the gas extraction pipeline to remove residual gas.

[0117] In this example, after each round of sampling, the PLC automatically closes the back pressure valve and starts the vacuum pump to evacuate the gas line to remove residual gas and ensure the purity of subsequent sampling.

[0118] Step 209: Induce the decomposition of the natural gas hydrate, and allow the gas released during the decomposition process to enter the isotope mass spectrometer for real-time isotope monitoring and analysis.

[0119] In this example, hydrate decomposition is induced and the isotopic evolution of the decomposed gases is continuously monitored by a mass spectrometer.

[0120] The above-mentioned method for continuous isotope monitoring of the hydrate formation and decomposition process disclosed herein covers the following three modes of use: single variable control mode, periodic perturbation mode, and multivariable coupling mode. The details are as follows:

[0121] In one example, the target mode is a single variable control mode, including: fixing all parameters except the target variable, where the target variable is one of temperature, pressure, salinity, gas composition or sedimentation medium; repeating the experiment and performing hydrate formation and decomposition experiments by changing the target variable value.

[0122] In this example, the single-variable control model involves controlling only a key variable (such as temperature, pressure, salinity, gas composition, or sedimentary medium) under a constant experimental environment to systematically investigate its influence on isotope fractionation during hydrate formation and decomposition. By maintaining other parameters constant, this model acquires isotope evolution data under different control conditions, enabling quantitative analysis of the relationship between the variable and the fractionation effect. This approach is suitable for exploring fundamental mechanisms and is an important approach for developing isotope fractionation models for hydrate systems.

[0123] In one example, the target mode is a periodic disturbance mode, including: controlling the electric back pressure valve through a PLC unit to automatically and cyclically adjust the pressure of the reaction chamber to decrease in a step-by-step manner according to a preset disturbance period; or, automatically and cyclically adjust the temperature of the reaction chamber according to a preset disturbance period through a water bath circulation pump; and after each preset disturbance period is completed, controlling the vacuum pump to evacuate the gas extraction pipeline.

[0124] In this example, the periodic perturbation mode simulates non-steady-state processes in natural environments by setting periodically varying experimental parameters (such as temperature cycling or pressure perturbations). During the experiment, a PLC unit or water bath circulating pump controls the cyclic changes in pressure or temperature over multiple perturbation cycles, continuously collecting gas isotope data to capture transient changes in the perturbation response. This mode can be used to study the dynamic response characteristics of hydrates in scenarios such as submarine geological hazards, geothermal activity, and artificial extraction of natural gas hydrates, revealing the evolution mechanisms of isotopes under non-equilibrium conditions.

[0125] In one example, the target mode is a multivariable coupling mode, including: synchronously regulating at least two associated variables, wherein the associated variables include but are not limited to temperature, pressure, gas component type, salinity, and sedimentary medium type; repeating the experiment and conducting hydrate formation and decomposition experiments by adjusting the combination of associated variables.

[0126] In this example, the multivariable coupling model introduces two or more variables into the experiment (e.g., coordinated changes in temperature and pressure, combined control of gas composition and salinity), creating complex experimental conditions to simulate the evolution of natural gas hydrates under the synergistic influence of multiple factors in actual sedimentary environments. This model focuses on the interaction between variables, helps to reproduce the fractionation scenarios of natural systems, optimize numerical simulation parameters, and provide support for resource assessment and geoenvironmental response research.

[0127] The present disclosure describes the above experimental process in detail through the following examples:

[0128] The test conditions and setting ranges are described as follows:

[0129] To ensure the scientificity and reproducibility of the natural gas hydrate formation-decomposition experiment, each experimental step must comply with the following key parameters:

[0130] Vacuum conditions:

[0131] The vacuum operation uses a vacuum pump to pre-evacuate the gas extraction pipeline to remove residual air and reduce the interference of the initial mixed gas on the isotope results.

[0132] Vacuuming duration: not less than 5 minutes, and can be set to automatically replenish vacuum at regular intervals (such as 2 hours) to maintain a stable low-pressure environment.

[0133] Vacuum conditions: The pressure in the gas extraction line is less than -0.085MPa, which is used to ensure that the residual gas is fully extracted and improve the sampling accuracy.

[0134] Temperature control range: The temperature control equipment consists of a water bath and a water bath circulation pump, with real-time feedback control from a temperature sensor.

[0135] Temperature control accuracy: ±0.1℃.

[0136] Adjustable temperature range: 0℃~30℃.

[0137] The commonly used temperature setting value for hydrate formation is 2℃±0.5℃; the temperature in the decomposition stage is usually set at 8℃~15℃.

[0138] Confining pressure setting range:

[0139] Confining pressure is established by injecting water into the cavity between the rubber tube and the outer shell through a hand pump.

[0140] Pressure range: 0.5MPa~20MPa.

[0141] Common experimental confining pressure setting values: 8MPa~12MPa, determined according to the actual simulated formation pressure.

[0142] Reaction gas injection pressure and flow rate:

[0143] Reaction gas pressure control range: 2MPa~20MPa.

[0144] The initial gas injection pressure is usually set at 6MPa to 12MPa to ensure that the hydrate stability zone is reached at the set temperature.

[0145] Flow control: set by flow meter, the common flow range is 20~80mL / min.

[0146] Back pressure valve control setting:

[0147] Back pressure setting value: 0.1MPa~0.5MPa, used to adjust the release rate to ensure that the sample enters the mass spectrometer stably.

[0148] Back pressure valve opening time: 5 to 10 seconds per round.

[0149] Isotope mass spectrometer working conditions:

[0150] Analysis method: continuous flow-stable isotope mass spectrometry (CF-IRMS) mode.

[0151] Measured isotopes: , wait.

[0152] Analysis frequency: Single sampling can be completed within 1 to 3 minutes, and high-frequency continuous sampling is supported.

[0153] Example 1 (Single Variable Control Mode): A method for continuous isotope monitoring of natural gas hydrate formation-decomposition process under single variable (e.g., temperature) control:

[0154] (1) Open the stainless steel housing, clean the rubber cylinder with distilled water and blow it dry thoroughly; add the soaked core sample or a set volume of water sample (such as 10 mL of deionized water) into the cylinder; then, close the stainless steel housing and seal the high-pressure reaction system to complete the initial preparation.

[0155] (2) Close the electric back pressure valve, start the vacuum pump, and evacuate the gas pipeline to remove residual gas in the system and ensure sampling accuracy.

[0156] (3) Start the water bath circulation pump, set the water bath temperature to the target temperature of this round of experiments (such as 2°C), start the online computer, check whether the status of the first temperature sensor and the first pressure sensor are normal, and confirm that the PLC control unit is well connected to each module.

[0157] (4) Use a hand pump to pass water into the cavity between the rubber tube and the stainless steel shell to establish and maintain a consistent confining pressure (e.g., 6 MPa), which is monitored and adjusted in real time by a second pressure sensor.

[0158] (5) Open the air inlet valve and inject the reaction gas into the rubber cylinder through the ventilation pipe to connect the high-pressure gas cylinder to ensure that the composition and flow rate of the injected gas in each experimental group are consistent (such as pure methane). The pressure of the reaction chamber is monitored by the first pressure sensor, and the air inlet rate is adjusted by the third pressure sensor and the flow meter. The system records the injection flow and pressure dynamics in real time ( Figure 3 、 Figure 4 ).

[0159] (6) When the gas pressure in the reaction chamber meets the hydrate formation conditions, the air inlet valve is closed, the system maintains the set temperature, and enters the spontaneous hydrate formation stage; the sensor continuously records the changes in the reaction chamber temperature, pressure and other parameters ( Figure 5 、 Figure 6 ).

[0160] (7) During the hydrate formation stage, the PLC unit opens the electric back pressure valve according to the preset program, so that the free gas in the rubber cylinder is slowly released under the control of the set back pressure; the released gas enters the isotope mass spectrometer through the one-way valve for real-time online isotope analysis; the system automatically records the key parameters such as temperature, pressure, flow rate, etc. corresponding to each round of gas extraction.

[0161] (8) After each round of sampling, the PLC unit controls the closing of the electric back pressure valve and restarts the vacuum pump to evacuate the gas pipeline and remove residual gas.

[0162] (9) When the second pressure sensor shows that the confining pressure is stable and hydrate formation is complete, the confining pressure is kept constant and the water bath temperature is raised to a temperature higher than the stable temperature to induce hydrate decomposition; the system continuously monitors and records changes in temperature, pressure and other parameters ( Figure 7 、 Figure 8 ).

[0163] (10) During the hydrate decomposition process, the PLC unit continuously controls the electric back pressure valve to allow the released gas to stably enter the isotope mass spectrometer, realizing continuous sampling and isotope online analysis throughout the process. Figure 9 )

[0164] (11) After the sampling is completed, continue to start the vacuum pump to evacuate the gas pipeline to prepare for the next experiment (such as the hydrate formation experiment at 6°C).

[0165] (12) When the pressure of the first pressure sensor drops to near atmospheric pressure, it indicates that the hydrate is completely decomposed. Turn off the online computer and save and analyze the obtained data.

[0166] (13) Repeat steps (1)-(12) and run the experimental groups under different control variables (such as 4°C and 6°C) to establish the functional relationship between the variable and the fractionation effect.

[0167] Example 2 (Periodic Perturbation Mode): A method for continuous isotope monitoring of natural gas hydrate formation-decomposition process in periodic perturbation mode:

[0168] (1) Open the stainless steel housing, clean the rubber cylinder with distilled water, and blow dry thoroughly. Add a soaked core sample or a set volume of water sample (e.g., 10 mL of deionized water) into the cylinder. Then, close the stainless steel housing and seal the high-pressure reaction system to complete the initial preparation.

[0169] (2) Close the electric back pressure valve, start the vacuum pump, and evacuate the gas pipeline to remove residual gas in the system and ensure sampling accuracy.

[0170] (3) Start the water bath circulation pump, set the target temperature (such as 2°C), then connect to the computer and check the status of the first temperature sensor and the first pressure sensor to ensure that the PLC control unit communicates normally with each module.

[0171] (4) Use a hand pump to inject water into the cavity between the rubber tube and the stainless steel shell to establish and maintain a constant confining pressure (e.g., 6 MPa). The second pressure sensor is used for real-time monitoring and adjustment, and the system automatically records parameters such as temperature and pressure.

[0172] (5) Open the air inlet valve and inject the reaction gas (such as pure methane) into the rubber cylinder through the ventilation pipe. The composition of the injected gas remains unchanged during each experimental cycle. The pressure in the cavity is monitored by the first pressure sensor, and the third pressure sensor is linked with the flow meter to adjust the air intake rate. The system records the injection flow rate and pressure change curve ( Figure 3 、 Figure 4 ).

[0173] (6) When the gas pressure in the reaction chamber meets the hydrate formation conditions, the air inlet valve is closed, the system maintains the set temperature, and enters the spontaneous hydrate formation stage; the sensor continuously records the changes in the reaction chamber temperature, pressure and other parameters ( Figure 5 、 Figure 6 ).

[0174] (7) During the hydrate formation stage, the PLC unit opens the electric back pressure valve according to the preset program, so that the free gas in the rubber cylinder is slowly released under the control of the set back pressure; the released gas enters the isotope mass spectrometer through the one-way valve for real-time online isotope analysis; at the same time, the system automatically records the key parameters such as temperature, pressure, flow rate, etc. corresponding to each round of gas extraction.

[0175] (8) After each round of sampling, the PLC unit controls the closing of the electric back pressure valve and restarts the vacuum pump to evacuate the gas pipeline and remove residual gas.

[0176] (9) When the pressure of the second pressure sensor stabilizes, hydrate formation is complete. Thereafter, according to the experimental design, periodic control is applied to the disturbance variable. For example, the temperature is set to cycle between 2°C, 4°C, and 6°C at a specific period (such as every 2 hours), or the pressure is set to slowly decrease in a step-by-step manner to simulate a natural disturbance environment. The PLC system automatically adjusts the target variable according to the set period, and the other variables remain unchanged ( Figure 10 、 Figure 11 ).

[0177] (10) Under periodic disturbance conditions, the PLC unit continuously controls the electric back pressure valve, so that the gas released during the decomposition process can stably enter the isotope mass spectrometer, realizing continuous sampling and isotope online analysis of the whole process ( Figure 9 ).

[0178] (11) During the experiment, the air line was automatically evacuated after each round of disturbance until the end of the last disturbance cycle.

[0179] (12) When the pressure of the first pressure sensor drops to the same level as the external atmospheric pressure, it indicates that the hydrate has completely decomposed. Turn off the online computer and save and analyze the obtained data.

[0180] Example 3 (Multivariable Coupling Mode): A method for continuous isotope monitoring of natural gas hydrate formation-decomposition process in a multivariable coupling mode:

[0181] (1) Open the stainless steel shell, clean the rubber cylinder with distilled water and blow it dry thoroughly; according to the experimental requirements, add the soaked core sample or a set volume of water sample into the cylinder. The water sample can be pure water, deionized water or simulated pore water containing specific salt ions to meet the simulation requirements of different experimental conditions; then, close the stainless steel shell and seal the high-pressure reaction system to complete the initial state preparation before the experiment.

[0182] (2) Close the electric back pressure valve, start the vacuum pump, and evacuate the gas pipeline to remove residual gas in the system and ensure sampling accuracy.

[0183] (3) Start the water bath circulation pump, set the target temperature, start the online computer, check whether the status of various sensors (including the first temperature sensor and the first pressure sensor) is normal, and confirm the communication connection between the PLC control unit and each module.

[0184] (4) Use a hand pump to pass water into the cavity between the rubber tube and the stainless steel shell to establish confining pressure; based on the data from the second pressure sensor, determine in real time whether the confining pressure level reaches the experimental set value.

[0185] (5) Open the air inlet valve and inject the reaction gas into the rubber tube through the ventilation pipe connected to the high-pressure gas cylinder. The reaction gas can be methane, ethane or other multi-component mixed gas; monitor the pressure in the cavity through the first pressure sensor, and adjust the air inlet rate through the linkage of the third pressure sensor and the flow meter. The system synchronously records the dynamic curve of the gas injection flow and pressure ( Figure 3 、 Figure 4 ).

[0186] (6) When the gas pressure in the reaction chamber meets the conditions for hydrate formation, the air inlet valve is closed, the system maintains the set temperature, and enters the spontaneous hydrate formation stage; during this stage, each sensor continuously records the changes in parameters such as the temperature and pressure of the reaction chamber.

[0187] (7) During the hydrate formation stage, the PLC unit opens the electric back pressure valve according to the preset program, so that the free gas in the rubber cylinder is slowly released under the control of the set back pressure; the released gas enters the isotope mass spectrometer through the one-way valve for real-time online isotope analysis; at the same time, the system automatically records the key parameters such as temperature, pressure, flow rate, etc. corresponding to each round of gas extraction.

[0188] (8) After each round of sampling, the PLC unit controls the closing of the electric back pressure valve and restarts the vacuum pump to evacuate the gas pipeline and remove residual gas.

[0189] (9) When the pressure of the second pressure sensor is stable, hydrate formation is complete. At this time, according to the experimental design, the water bath temperature can be adjusted or the electric back pressure valve can be opened to release the pressure, so that the system enters the hydrate decomposition stage. The system continuously monitors and records the changes in physical parameters such as temperature and pressure ( Figure 7 、 Figure 8 ).

[0190] (10) During the hydrate decomposition process, the PLC unit continuously controls the electric back pressure valve, so that the gas released during the decomposition process can stably enter the isotope mass spectrometer, realizing continuous sampling and isotope online analysis throughout the process ( Figure 9 ).

[0191] (11) After completing the sampling, continue to start the vacuum pump and evacuate the gas pipeline to prepare for the next experimental cycle.

[0192] (12) When the pressure of the first pressure sensor drops to the same level as the external atmospheric pressure, it indicates that the hydrate has completely decomposed. Turn off the online computer and save and analyze the obtained data.

[0193] It should be understood that the various forms of processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this disclosure can be performed in parallel, sequentially, or in a different order, as long as the desired results of the technical solutions of this disclosure can be achieved, and this document is not limited here.

[0194] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. Throughout the present disclosure, "plurality" means two or more, unless otherwise specifically defined.

[0195] The above description is merely a specific embodiment of the present disclosure, but the scope of protection of the present disclosure is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this disclosure should be included in the scope of protection of the present disclosure. Therefore, the scope of protection of the present disclosure should be based on the scope of protection of the claims.

Claims

1. A continuous isotope monitoring device for hydrate formation and decomposition process, characterized in that: The device comprises: The high-pressure reaction system includes a rubber cylinder (1), a stainless steel shell (2), a liquid inlet valve (3) and a hand pump (4), and is used to provide a pressure environment for the formation and decomposition of natural gas hydrates; The fluid control and automatic sampling system includes a vacuum pump (9), an electric back pressure valve (14), a gas extraction line (15), a one-way valve (16), an air inlet valve (20), a vent line (21) and a high-pressure gas cylinder (22), and is used to inject the reaction gas into the rubber cylinder (1) and control the automatic sampling of the gas; The continuous analysis and monitoring system includes a first temperature sensor (5), a second temperature sensor (11), a first pressure sensor (6), a second pressure sensor (12), a third pressure sensor (13), and an isotope mass spectrometer (17), and is used for real-time monitoring of temperature values, pressure values, and gas isotope composition; The temperature control circulation system includes a water bath circulation pump (7) and a water bath tank (18), which are used to provide a temperature environment for the formation and decomposition of natural gas hydrates; The data acquisition and control system includes an online computer (8), a programmable logic controller (PLC) unit (10) and a flow meter (19), which are used for real-time acquisition of experimental data, intelligent control of environmental parameters and result analysis; In the high pressure reaction system: The rubber tube (1) is filled with a water sample or a rock core to form a reaction cavity; The stainless steel shell (2) covers the rubber tube (1) to form a confined pressure cavity; The hand pump (4) is connected to the confining pressure chamber via a liquid inlet valve (3) and is used to inject water into the confining pressure chamber to increase pressure; In the fluid control and automatic sampling system: The high-pressure gas cylinder (22) is connected to the inlet end of the rubber cylinder (1) through the ventilation pipeline (21) and the air inlet valve (20) and is used to inject the reaction gas into the rubber cylinder (1); The inlet end of the gas extraction line (15) is connected to the outlet end of the rubber tube (1), and the outlet end of the gas extraction line is connected to the isotope mass spectrometer (17) through the electric back pressure valve (14) and the one-way valve (16) in sequence, for automatic sampling and providing the sample to the isotope mass spectrometer (17); The vacuum pump (9) is connected to the rubber cylinder (1) via the air extraction line (15) and the electric back pressure valve (14) and is used to evacuate the reaction chamber.

2. The device according to claim 1, characterized in that In the continuous analysis and monitoring system: The first temperature sensor (5) and the first pressure sensor (6) are connected to the inside of the rubber tube (1) and are used to detect a first temperature value and a first pressure value of the reaction chamber; The second temperature sensor (11) and the second pressure sensor (12) are connected to the confined pressure chamber and are used to detect a second temperature value and a second pressure value of the confined pressure chamber; The third pressure sensor (13) is arranged on the ventilation pipeline (21) and is used to detect a third pressure value in the ventilation pipeline (21).

3. The device according to claim 1, characterized in that In the temperature control circulation system: The water bath (18) covers the stainless steel housing (2); the water bath circulation pump (7) and the water bath (18) form a closed loop for controlling the temperature of the confining pressure chamber.

4. The device according to claim 1, characterized in that In the data acquisition and control system: The flow meter (19) is connected in series to the ventilation pipeline (21) and is used to measure the gas flow rate in the ventilation pipeline (21) and transmit the gas flow rate data to the online computer (8); and is also used to control the gas flow rate according to the first pressure value of the first pressure sensor (6); The online computer (8) is in communication connection with the output ends of the first temperature sensor (5), the second temperature sensor (11), the first pressure sensor (6), the second pressure sensor (12), the third pressure sensor (13) and the isotope mass spectrometer (17), and is used to obtain the first temperature value, the second temperature value, the first pressure value, the second pressure value, the third pressure value, the flow value and the isotope detection result; The PLC unit (10) is electrically connected to and controls the electric back pressure valve (14) and the vacuum pump (9); The PLC unit (10) performs data exchange with the online computer (8).

5. A method for continuous isotope monitoring of hydrate formation and decomposition process, characterized in that: The method is applied to the hydrate formation-decomposition process continuous isotope monitoring device according to any one of claims 1 to 4, and the method comprises: Perform the following monitoring steps in target mode: Injecting a sample into the rubber tube and sealing the rubber tube and the stainless steel shell; the sample is a core sample or a water sample of a set volume; Close the electric back pressure valve and start the vacuum pump to evacuate the gas extraction line; Start the water bath circulation pump and set the water bath temperature to the target temperature; Use a hand pump to pass water into the confining pressure cavity between the rubber cylinder and the stainless steel shell through the liquid inlet valve to establish the target confining pressure condition; Open the air inlet valve and inject the reaction gas into the rubber cylinder through the ventilation pipe connected to the high-pressure gas cylinder; When the gas pressure in the reaction chamber meets the conditions for natural gas hydrate formation, the gas inlet valve is closed to allow natural gas hydrate to form spontaneously; The electric back pressure valve is controlled by the PLC unit to release the gas, which then enters the isotope mass spectrometer through a one-way valve for real-time isotope monitoring and analysis. After each round of sampling, the PLC unit controls the closing of the electric back pressure valve and restarts the vacuum pump to evacuate the gas extraction line to remove residual gas; Induce the decomposition of natural gas hydrates, and allow the gases released during the decomposition process to enter the isotope mass spectrometer for real-time isotope monitoring and analysis.

6. The method according to claim 5, characterized in that The target mode is a single variable control mode, including: fixing all parameters except a target variable, wherein the target variable is one of temperature, pressure, salinity, gas composition, or deposition medium; The experiment was repeated and hydrate formation and decomposition experiments were performed by changing the value of the target variable.

7. The method according to claim 5, characterized in that The target mode is a periodic disturbance mode, including: The electric back pressure valve is controlled by a PLC unit to automatically and cyclically adjust the pressure of the reaction chamber to decrease in a step-by-step manner according to a preset disturbance period; or the temperature of the reaction chamber is automatically and cyclically adjusted by a water bath circulation pump according to a preset disturbance period; After each preset disturbance cycle is completed, the vacuum pump is controlled to evacuate the gas extraction line.

8. The method according to claim 5, characterized in that The target mode is a multivariable coupling mode, including: Synchronously regulating at least two correlated variables, wherein the correlated variables include temperature, pressure, salinity, gas composition, or deposition medium; The experiment was repeated and hydrate formation and decomposition experiments were performed by adjusting the combination of associated variables.

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