Large-scale natural gas hydrate development simulation device and experimental method thereof

Abstract

The invention relates to a large-scale natural gas hydrate development simulation device and an experimental method thereof. Comprising an injection-production well simulation pipe, a reaction kettle, a gas supply system for providing gas for the reaction kettle, a liquid supply system for providing liquid for the reaction kettle, a gas collection system for collecting gas generated in an experiment, a liquid collection system for collecting liquid generated in the experiment, a temperature control system for controlling the temperature of the reaction kettle, and a data acquisition and analysis system, the data acquisition and analysis system comprises multiple layers of sensing units which are arranged in the kettle body at intervals in the axial direction of the reaction kettle, each layer of sensing unit comprises multiple groups of sensors which are uniformly arranged at intervals in the circumferential direction of the kettle body, and each group of sensors comprises a temperature sensor, a pressure sensor and a water saturation sensor. And multiple layers of sensing units are arranged to collect data of synthesis and decomposition temperature, pressure and pore water saturation of the natural gas hydrate in a simulation experiment, so that the collected data are more comprehensive, the device is suitable for the simulation experiment of a large-size device, and the measurement data range is wide.

Description

Technical Field

[0001] The invention relates to the technical field of natural gas hydrate development simulation, and in particular to a large-scale natural gas hydrate development simulation device and an experimental method thereof. Background Art

[0002] Natural gas hydrate is a new type of clean energy with extremely broad development prospects and huge application space. At present, field exploration and trial production, indoor experiments and numerical simulations in the field of natural gas hydrates are progressing steadily, but the existing Tianrenqi hydrate simulation experiments mostly use small-sized devices for simulation, and there are limitations in the data required for measurement. The test conditions are quite different from the actual situation of natural gas hydrate development, and it is impossible to provide more comprehensive reference data and application value for field exploration and trial production, indoor experiments and numerical simulations. The natural gas hydrate development experimental simulation device of the present invention has the advantages of large size, wide measurement range of temperature, pressure and water saturation data, and reasonable control of the temperature required for the experiment. This experimental device improves the defects of the existing devices and provides more comprehensive reference data and application value for field exploration and trial production, indoor experiments and numerical simulations. Summary of the invention

[0003] The purpose of the present invention is to provide a large-scale natural gas hydrate development simulation device and an experimental method thereof, which is suitable for experimental simulation work of large-scale devices, has a wide range of measurement data, and provides more comprehensive reference data and application value for field exploration and trial production, indoor experiments and numerical simulation work.

[0004] To achieve the purpose of the present invention, the technical solution adopted is:

[0005] A large-scale natural gas hydrate development simulation device comprises an injection and production well simulation pipe, a reactor, a gas supply system connected to the reactor and providing gas to the reactor, a liquid supply system connected to the reactor and providing liquid to the reactor, a gas collection system connected to the reactor and used to collect gas generated by the reactor during experiments, a liquid collection system connected to the reactor and used to collect liquid generated by the reactor during experiments, a temperature control system for controlling the temperature of the reactor, and a data acquisition and analysis system for collecting experimental data, wherein the data acquisition and analysis system comprises a plurality of sensor units arranged in the reactor body at intervals along the axial direction of the reactor, each layer of the sensor units comprises a plurality of groups of sensors evenly spaced along the circumference of the reactor body, and each group of sensors comprises a temperature sensor, a pressure sensor and a water saturation sensor.

[0006] The natural gas hydrate development simulation device is equipped with multiple layers of sensing units in the kettle body, and each layer of sensing units is equipped with multiple groups of sensors to collect data on temperature, pressure and pore water saturation of natural gas hydrate synthesis and decomposition during the simulation experiment, making the collected data more comprehensive and suitable for simulation experiments of large-scale devices. The measurement data has a wide range and provides more comprehensive reference data and application value for field exploration and trial production, indoor experiments and numerical simulation work.

[0007] The following is a further description of the technical solution:

[0008] Furthermore, the temperature control system includes a low-temperature water tank, a high-temperature water tank, and a double helical tube wound around the outer wall of the reactor body, and the double helical tube includes a low-temperature helical tube connected to the low-temperature water tank and a high-temperature helical tube connected to the high-temperature water tank. The reactor is cooled by passing cold water into the low-temperature helical tube, and the reactor is heated by passing hot water into the high-temperature helical tube, so that the temperature control of the reactor is more accurate, the temperature required for the experiment is reasonably controlled, and the adaptability is wider.

[0009] Furthermore, both the low-temperature spiral pipe and the high-temperature spiral pipe are wrapped with a heat-insulating layer, which reduces heat loss and thus achieves a better heat-insulating effect.

[0010] Furthermore, the reactor also includes a top cover and a bottom cover respectively arranged at both ends of the reactor body, and a partition arranged in the reactor body, the partition is provided with a plurality of first through holes for the data transmission lines of the sensor to pass through and second through holes for the injection and production well simulation pipes to pass through, the top cover is provided with a liquid inlet, an air outlet, a glue injection port, and a wiring port for integrating the data transmission line, and the bottom cover is provided with an air inlet and a liquid outlet.

[0011] Furthermore, the air supply system includes an air supply device, an air intake pipe whose two ends are connected to the air supply device and the air inlet respectively, and the air intake pipe is connected with an air flow meter, an air intake regulating valve, an air intake compressor and an air intake check valve in sequence.

[0012] Furthermore, the liquid supply system includes a liquid supply device, a liquid inlet pipe whose two ends are connected to the liquid supply device and the liquid inlet respectively, and the liquid inlet pipe is connected in sequence with a liquid inlet flow meter, a liquid inlet check valve, a booster pump and a liquid inlet regulating valve.

[0013] Furthermore, the development simulation device also includes a booster gas compressor. The gas collection system includes a gas collecting device, a gas outlet pipe whose two ends are respectively connected to the gas collecting device and the gas outlet, the gas outlet pipe is connected in sequence with a gas outlet regulating valve, a vacuum pump, a gas outlet check valve and a gas outlet flow meter, the booster gas compressor is connected to the gas outlet pipe, and the pressure in the kettle is adjusted by the booster gas compressor.

[0014] Furthermore, the liquid collection system includes a liquid collecting device, a liquid outlet pipe with two ends respectively connected to the liquid collecting device and the liquid outlet, and the liquid outlet pipe is connected in sequence with a liquid outlet regulating valve, a liquid constant flow pump, a liquid outlet check valve and a liquid outlet flow meter.

[0015] The present invention also provides an experimental method for the above-mentioned large-scale natural gas hydrate development simulation device, characterized in that it comprises the following steps:

[0016] S1. According to the base sand ratio scheme, a mixture including sodium chloride solution, quartz sand of different mesh sizes and natural sodium-based bentonite is prepared;

[0017] S2. Insert the injection and production well simulation pipe into the axis position of the reactor, lay the mixture layer by layer according to the preset position of each layer of sensor units, after each layer of the mixture is laid, first arrange the sensor units of the corresponding layer, and then lay the next layer of the mixture, until all the sensor units are arranged, and finally fill the reactor body with the mixture, pull out the injection and production well simulation pipe, insert the injection and production well simulation pipe into the reactor from the liquid inlet, place the partition on the mixture, pass the data transmission line of the sensor unit through the partition and integrate it, pass the integrated data transmission line through the wiring port, and seal the top cover on the reactor body;

[0018] S3, injecting glue liquid through the glue injection port to fill the space between the partition and the top cover, and controlling the temperature of the temperature control system to make the glue liquid form a colloid filling layer required for the experiment;

[0019] S4, only open the exhaust port to exhaust all the air in the kettle body, and close the exhaust port after a negative pressure environment is formed in the kettle body;

[0020] S5, open the air inlet, inject nitrogen into the reactor, fill the reactor with nitrogen and make the pressure in the reactor reach a first preset pressure value, close the air inlet, and let the reactor stand for a first preset time; if the pressure in the reactor does not change within the first preset time, execute step S6; if the pressure in the reactor changes within the first preset time, check the gas leakage location and repair it, exhaust all the gas, and repeat step S5;

[0021] S6, open the liquid inlet, inject pure water into the reactor until the reactor is filled, open the exhaust port, exhaust all the nitrogen, close the exhaust port, let the reactor stand for a second preset time, and during the second preset time, turn on the temperature control system to keep the temperature in the reactor stable;

[0022] S7, opening the air inlet, injecting methane gas into the reactor, and opening the drain port to discharge excess pure water in the reactor body, until the reactor is filled with methane gas and the pressure in the reactor reaches a second preset pressure value or higher, closing the drain port, and the natural gas hydrate synthesis reaction begins;

[0023] S8. During the natural hydrate synthesis process, continuously injecting methane gas into the reactor to make the pressure in the reactor reach a third preset pressure value, closing the air inlet, and turning on the temperature control system to keep the temperature in the reactor within the first preset temperature value;

[0024] S9, after the pressure in the kettle body is stable, open the air inlet, inject methane gas into the reactor and make the pressure in the reactor reach above the second preset pressure value, and after the temperature and pressure in the reactor body remain stable for a third preset time, the synthesis process of natural gas hydrate is completed;

[0025] S10, observing the data measured by the sensor units, if the difference between the measured data of two adjacent layers of sensor units is within the preset value range, executing step S11; if the difference between the measured data of two adjacent layers of sensor units exceeds the preset value, terminating the experiment and re-executing steps S2 to S9;

[0026] S11, if the natural gas hydrate is mined by the heat injection method, then execute step S12; if the natural gas hydrate is mined by the heating method, then execute step S13;

[0027] S12. Open the exhaust port and the liquid discharge port to collect the natural gas and water obtained from the experimental decomposition, and simultaneously inject pure water of the second preheating temperature into the injection-production well simulation pipe. The data acquisition and analysis system collects the decomposition data of the natural gas hydrate in real time. After the natural gas discharge is completed, the data acquisition and analysis system saves and analyzes the collected data.

[0028] S13. Open the exhaust port and the liquid discharge port to collect the natural gas and water obtained from the experimental decomposition. The temperature control system sets the second preheating temperature to heat the kettle body. The data acquisition and analysis system collects the decomposition data of the natural gas hydrate in real time. After the natural gas is discharged, the data acquisition and analysis system saves and analyzes the collected data.

[0029] Furthermore, in step S3, there are two glue injection ports, and the glue is injected from one of the glue injection ports, and the kettle body is heated by the temperature control system. When the glue overflows from the other glue injection port, the temperature control system stops heating the kettle body. After the glue is allowed to stand for a fourth preset time, the kettle body is heated to a third preheating temperature by the temperature control system and maintained at a constant temperature for a fifth preset time, and then the temperature control system is turned off to allow the glue to cool to form a glue filling layer required for the experiment.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] The natural gas hydrate development simulation device of the present invention is provided with multiple layers of sensing units on the kettle body, and each layer of sensing units is provided with multiple groups of sensors to collect data on temperature, pressure and pore water saturation of natural gas hydrate synthesis and decomposition during the simulation experiment, so that the collected data is more comprehensive and the experimental data is more accurate. It is suitable for simulation experiments of large-scale devices and has a wide range of measurement data, providing more comprehensive reference data and application value for field exploration and trial production, indoor experiments and numerical simulation work. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the connection plane of a large-scale natural gas hydrate development simulation device according to an embodiment of the present invention;

[0033] Figure 2 It is a three-dimensional schematic diagram of the connection of a large-scale natural gas hydrate development simulation device according to an embodiment of the present invention;

[0034] Figure 3 It is a schematic structural diagram of a reaction kettle according to an embodiment of the present invention;

[0035] Figure 4 is a schematic diagram of a sensor according to an embodiment of the present invention;

[0036] Figure 5 It is a schematic structural diagram of a partition according to an embodiment of the present invention.

[0037] Description of reference numerals:

[0038] 1. First gas collection container, 2. First regulating valve, 3. First vacuum pump, 4. First check valve, 5. First gas flow meter, 6. Second check valve, 7. First booster pump, 8. Second regulating valve, 9. Pure water supplier, 10. First liquid flow meter, 11. Data acquisition and analysis system, 12. Second gas flow meter, 13. Third check valve, 14. Second vacuum pump, 15. Third regulating valve, 16. Second gas collection container, 17. High temperature water tank, 18. , the fourth regulating valve, 19, the first centrifugal pump, 20, the fourth check valve, 21, the fifth regulating valve, 22, the second centrifugal pump, 23, the fifth check valve, 24, the second liquid flow meter, 25, the sixth check valve, 26, the sixth regulating valve, 27, the first liquid collecting device, 28, the first liquid constant flow pump, 29, the second liquid constant flow pump, 30, the second liquid collecting device, 31, the seventh regulating valve, 32, the seventh check valve, 33, the third liquid flow meter, 34, Main valve, 35, eighth check valve, 36, first gas compressor, 37, eighth regulating valve, 38, third gas flow meter, 39, nitrogen cylinder, 40, ninth check valve, 41, second gas compressor, 42, ninth regulating valve, 43, fourth gas flow meter, 44, methane cylinder, 45, tenth check valve, 46, third centrifugal pump, 47, tenth regulating valve, 48, low temperature spiral tube, 49, high temperature spiral tube, 50, reactor, 501, top cover, 50 11. liquid inlet, 5012. air outlet, 5013. glue injection port, 5014. wiring port, 502. bottom cover, 503. partition, 5031. first through hole, 5032. second through hole, 5033. third through hole, 504. kettle body, 51. eleventh check valve, 52. fourth centrifugal pump, 53. eleventh regulating valve, 54. low-temperature water tank, 55. sensor, 56. bottom plate, 57. first bracket, 58. second bracket, 59. platform guardrail, 60. escalator. DETAILED DESCRIPTION

[0039] The embodiments of the present invention are described in detail below with reference to the accompanying drawings:

[0040] like Figures 1 to 4As shown, a large-scale natural gas hydrate development simulation device includes an injection and production well simulation pipe, a reactor 50, a gas supply system connected to the reactor 50 and providing gas to the reactor 50, a liquid supply system connected to the reactor 50 and providing liquid to the reactor 50, a gas collection system connected to the reactor 50 and used to collect the gas generated by the reactor 50 during the experiment, a liquid collection system connected to the reactor 50 and used to collect the liquid generated by the reactor 50 during the experiment, a temperature control system for controlling the temperature of the reactor 50, and a data acquisition and analysis system 11 for collecting experimental data. The data acquisition and analysis system 11 includes a plurality of sensor units arranged in a reactor body 504 along the axial direction of the reactor 50 and a data processing unit for analyzing the data. Each layer of the sensor units includes a plurality of groups of sensors 55 evenly spaced along the circumference of the reactor body 504, and each group of sensors 55 includes a temperature sensor, a pressure sensor, and a water saturation sensor.

[0041] The natural gas hydrate development simulation device is equipped with multiple layers of sensing units on the kettle body 504, and each layer of sensing units is equipped with multiple groups of sensors 55 to collect data on temperature, pressure and pore water saturation of natural gas hydrate synthesis and decomposition during the simulation experiment, so that the collected data is more comprehensive and suitable for simulation experiments of large-scale devices. The measurement data has a wide range and provides more comprehensive reference data and application value for field exploration and trial production, indoor experiments and numerical simulation work.

[0042] In this embodiment, the data acquisition and analysis system 11 includes four layers of sensor units, which are arranged at 200mm, 400mm, 600mm and 800mm horizontal circular surfaces every 200mm in the longitudinal direction of the kettle body 504, and each layer of sensor units includes four groups of sensors 55. The four groups of sensors 55 are arranged at a point every 90° along the circumferential direction in the transverse horizontal circular surface of each layer, and each arrangement point is evenly arranged with a temperature sensor, a pressure sensor and a water saturation sensor, totaling sixteen temperature sensors, sixteen pressure sensors and sixteen water saturation sensors.

[0043] The temperature sensor adopts a four-wire high-pressure thermal resistor sensor; the pressure sensor adopts a pore water pressure gauge; the water saturation sensor measures the water saturation in the pores through the principle of water-electricity similarity. The electrode system is a group of electrodes arranged in a certain order, consisting of power supply electrodes A, B and measuring electrodes M, N. At 800mm from the bottom of the kettle, the pressure, high-pressure thermal resistor, and electrode lines are arranged clockwise; at 600mm, the high-pressure thermal resistor, pressure, and electrode lines are arranged clockwise; at 400mm, the high-pressure thermal resistor, electrode, and pressure lines are arranged clockwise; at 200mm, the electrode, high-pressure thermal resistor, and pressure lines are arranged clockwise. The data transmission line of sensor 55 is concentrated in the steel pipe to form a wiring pipeline, such as Figure 3 and Figure 5As shown, the partition 503 is used to bring the data lines together, and then connected to the data processing unit through the wiring port 5014 on the top cover 501, so as to realize the data collection of temperature, pressure and pore water saturation when conducting natural gas hydrate development simulation, thereby obtaining the temperature, pressure and pore water saturation data that are most suitable for natural gas hydrate synthesis and decomposition.

[0044] like Figure 3 As shown, the reaction kettle 50 at least includes a kettle body 504, a top cover 501, a bottom cover 502, and a partition 503. The top cover 501 and the kettle body 504, and the bottom cover 502 and the kettle body 504 are connected by bolts.

[0045] In this embodiment, a liquid inlet 5011, two gas outlets 5012, two glue injection ports 5013 and two wiring ports 5014 are provided on the top cover 501, and the liquid inlet 5011, the gas outlet 5012, the glue injection port 5013 and the wiring port 5014 are all located on the same horizontal plane. The liquid inlet 5011 is located at the center of the top cover 501, and the liquid inlet 5011 cooperates with the injection and production well simulation pipe to provide liquid raw materials and pressure environment to the reactor 50; the wiring port 5014 is used to integrate the data transmission of the sensor 55; the gas outlet 5012 is used to connect the gas outlet pipeline to discharge or collect the gas generated during the synthesis and decomposition of natural gas hydrates; the glue injection port 5013 is used to inject glue into the top of the reactor 50.

[0046] The bottom cover 502 is provided with an air inlet and two liquid outlets, which are located on the same horizontal plane. The air inlet is located at the center of the bottom cover 502 and is used to connect the air inlet pipeline to provide gas raw materials to the reactor 50; the liquid outlet is used to connect the liquid outlet pipeline to discharge or collect the liquid generated during the synthesis and decomposition of natural gas hydrates.

[0047] The reactor 50 is provided with a partition 503, and the position of the partition 503 is determined according to the height of the quartz sand. Figure 5 As shown, the partition 503 is disc-shaped, and a first through hole 5031 is provided in the center of the partition 503 for cooperating with the injection and production well simulation pipe; the partition 503 is also provided with four second through holes 5032 evenly arranged along the circumference, and the second through holes 5032 are used to cooperate with the wiring pipeline of the sensor 55. The data transmission lines of the sensor 55 are concentrated in four steel pipes to form the wiring pipeline; the partition 503 is also provided with a third through hole 5033 symmetrically arranged with the center of the partition 503 for cooperating with the gas outlet pipeline.

[0048] A screening device is arranged at the bottom of the reaction kettle 50. The screening device includes a sponge and a filter screen to prevent quartz sand from clogging the air intake pipe.

[0049] like Figure 1 and Figure 2As shown, the air supply system includes an air supply device, an air intake pipe with two ends connected to the air supply device and the air inlet respectively, and the air intake pipe is connected with an air intake flow meter, an air intake regulating valve, an air intake compressor and an air intake check valve in sequence.

[0050] In this embodiment, the gas supply equipment includes a nitrogen gas cylinder 39 and a methane gas cylinder 44, which are used to inject methane and nitrogen into the reactor 50 to provide the reactor 50 with raw materials for hydrate synthesis and a certain pressure environment. Figure 1 As shown, an air intake pipeline is connected between the nitrogen cylinder 39 and the reactor 50, and the air intake pipeline of the nitrogen cylinder 39 is sequentially provided with a third gas flow meter 38, an eighth regulating valve 37, a first gas compressor 36 and an eighth check valve 35; an air intake pipeline is also connected between the methane cylinder 44 and the reactor 50, and the air intake pipeline of the methane cylinder 44 is sequentially provided with a fourth gas flow meter 43, a ninth regulating valve 42, a fourth gas compressor 41 and a ninth check valve 40, and the last two air intake pipes are connected together and the switch is controlled by the main valve 34. Under the action of the first gas compressor 36 or the second gas compressor 41, nitrogen or methane is injected from the air intake pipe into the air inlet at the bottom of the reactor 50.

[0051] like Figure 1 and Figure 2 As shown, the liquid supply system includes a liquid supply device, a liquid inlet pipe whose two ends are connected to the liquid supply device and the liquid inlet 5011 respectively, and the liquid inlet pipe is connected with a liquid inlet flow meter, a liquid inlet check valve, a booster pump and a liquid inlet regulating valve in sequence.

[0052] In this embodiment, if Figure 1 As shown, the liquid supply device is a pure water supplier 9, and a liquid inlet pipeline is arranged between the pure water supplier 9 and the reactor 50, and the liquid inlet pipeline is sequentially provided with a first liquid flow meter 10, a second check valve 6, a first booster pump 7 and a second regulating valve 8. The liquid supply system can not only inject water required for the experiment into the reactor 50 through the injection and production well simulation pipe in the reactor 50 to provide the raw materials required for the natural gas hydrate synthesis reaction, but also inject water to detect the air tightness of the device.

[0053] like Figure 1 and Figure 2 As shown, the development simulation device also includes a booster gas compressor, and the gas collection system includes a gas collecting device, an outlet pipe whose two ends are respectively connected to the gas collecting device and the gas outlet 5012, and the outlet pipe is connected with an outlet regulating valve, a vacuum pump, an outlet check valve and an outlet flow meter in sequence, and the booster gas compressor is connected to the outlet pipe, and the pressure in the kettle body 504 is adjusted by the booster gas compressor.

[0054] In this embodiment, if Figure 1As shown, the gas collection equipment includes a first gas collection container 1 and a second gas collection container 16. A first regulating valve 2, a first vacuum pump 3, a first check valve 4 and a first gas flow meter 5 are sequentially arranged on the gas outlet pipeline between the first gas collection container 1 and the reactor 50; a third regulating valve 15, a second vacuum pump 14, a third check valve 13 and a second gas flow meter 12 are sequentially arranged on the gas outlet pipeline between the second gas collection container 16 and the reactor 50. The first vacuum pump 3 and the second vacuum pump 14 are used to achieve the vacuum conditions required for the simulation development of natural gas hydrates.

[0055] like Figure 1 and Figure 2 As shown, the liquid collection system includes a liquid collecting device, a liquid outlet pipe with two ends respectively connected to the liquid collecting device and the liquid outlet, and the liquid outlet pipe is connected in sequence with a liquid outlet regulating valve, a liquid constant flow pump, a liquid outlet check valve and a liquid outlet flow meter.

[0056] In this embodiment, if Figure 1 As shown, the liquid collecting device includes a first liquid collecting device 27 and a second liquid collecting device 30, and the first liquid collecting device 27 and the second liquid collecting device 30 are respectively connected to the reactor 50 through liquid outlet pipes, and the liquid outlet pipe between the first liquid collecting device 27 and the reactor 50 is provided with a sixth regulating valve 26, a first liquid constant flow pump 28, a sixth check valve 25 and a second liquid flow meter 24 in sequence; the liquid outlet pipe between the second liquid collecting device 30 and the reactor 50 is provided with a seventh regulating valve 31, a second liquid constant flow pump 29, a seventh check valve 32 and a third liquid flow meter 33 in sequence.

[0057] like Figure 1 and Figure 3 As shown, the temperature control system includes a low temperature water tank 54, a high temperature water tank 17, and a double helical tube wound around the outer wall of the kettle body 504, and the double helical tube includes a low temperature helical tube 48 connected to the low temperature water tank 54, and a high temperature helical tube 49 connected to the high temperature water tank 17. The connecting pipe between the high temperature water tank 17 and the high temperature helical tube 49 is provided with a fourth regulating valve 18, a first centrifugal pump 19, a fourth check valve 20, a fifth check valve 23, a second centrifugal pump 22 and a fifth regulating valve 21 in sequence; the connecting pipe between the low temperature water tank 54 and the low temperature helical tube 48 is provided with an eleventh regulating valve 53, a fourth centrifugal pump 52, an eleventh check valve 51, a tenth check valve 45, a third centrifugal pump 46 and a tenth regulating valve 47 in sequence, and hot water and cold water are cyclically injected into the double helical tube to control the temperature required for the synthesis and decomposition of natural gas hydrates, so that the temperature control of the reactor 50 is more accurate, the temperature required for the experiment is reasonably controlled, and the adaptability is wider.

[0058] The low-temperature spiral tube 48 and the high-temperature spiral tube 49 are both wrapped with a thermal insulation layer, which reduces heat loss and achieves a better thermal insulation effect.

[0059] like Figure 2 As shown, the development simulation device also includes an auxiliary system. The auxiliary system uses a cement board 56 as a bottom plate 56. The first bracket 5757 and the second bracket 5858 support the reactor body 50. The reactor body 504 passes through the first bracket 57 and the second bracket 58. The first bracket 57 is provided with a platform guardrail 5959 and an escalator 6060. The escalator 60 handrail bottom plate 56 is at an angle of 60°, which is convenient for personnel to operate and ensures safe operation.

[0060] The experimental method for developing the simulation described above comprises the following steps:

[0061] S1. According to the base sand ratio scheme, a mixture including sodium chloride solution, quartz sand of different mesh sizes and natural sodium-based bentonite is prepared;

[0062] S2, insert the injection and production well simulation pipe into the axis position of the reactor 50, lay the mixture layer by layer according to the preset position of each layer of sensor units, after each layer of the mixture is laid, first arrange the sensor units of the corresponding layer, and then lay the next layer of the mixture, until all the sensor units are arranged, and finally fill the kettle 504 with the mixture, and pull out the injection and production well simulation pipe, insert the injection and production well simulation pipe into the reactor 50 from the liquid inlet 5011, place the partition 503 on the mixture, the data transmission line of the sensor unit passes through the partition 503 and is integrated, the integrated data transmission line passes through the wiring port 5014, and the top cover 501 is sealed on the kettle 504;

[0063] S3, injecting glue through the glue injection port 5013, so that the glue is filled between the partition 503 and the top cover 501, and the temperature of the temperature control system is controlled so that the glue forms a colloid filling layer required for the experiment;

[0064] S4, only open the exhaust port to exhaust all the air in the kettle body 504, and close the exhaust port after a negative pressure environment is formed in the kettle body 504;

[0065] S5, open the air inlet, inject nitrogen into the reactor 50, fill the reactor 50 with nitrogen and make the pressure in the reactor reach a first preset pressure value, close the air inlet, and let the reactor 50 stand for a first preset time; if the pressure in the reactor does not change within the first preset time, execute step S6; if the pressure in the reactor changes within the first preset time, check the gas leakage location and repair it, exhaust all the gas, and repeat step S5;

[0066] S6, open the liquid inlet 5011, inject pure water into the reactor 50 until the reactor 50 is filled, open the exhaust port, exhaust all the nitrogen, close the exhaust port, and let the reactor 50 stand for a second preset time. During the second preset time, turn on the temperature control system to keep the temperature in the reactor stable;

[0067] S7, opening the air inlet, injecting methane gas into the reactor 50, and opening the drain port to discharge the excess pure water in the reactor body 504, until the reactor 50 is filled with methane gas and the pressure in the reactor reaches a second preset pressure value or higher, closing the drain port, and the natural gas hydrate synthesis reaction begins;

[0068] S8, during the natural hydrate synthesis process, continuously injecting methane gas into the reactor 50 to make the pressure in the reactor reach a third preset pressure value, closing the air inlet, and turning on the temperature control system to keep the temperature in the reactor within the first preset temperature value;

[0069] S9, after the pressure in the kettle 504 is stable, the air inlet is opened, and methane gas is injected into the reactor 50 to make the pressure in the reactor reach a second preset pressure value or higher. After the temperature and pressure in the kettle 504 remain stable for a third preset time, the synthesis process of natural gas hydrate is completed;

[0070] S10, observing the data measured by the sensor units, if the difference between the measured data of two adjacent layers of sensor units is within the preset value range, executing step S11; if the difference between the measured data of two adjacent layers of sensor units exceeds the preset value, terminating the experiment and re-executing steps S2 to S9;

[0071] S11, if the natural gas hydrate is mined by the heat injection method, then execute step S12; if the natural gas hydrate is mined by the heating method, then execute step S13;

[0072] S12. Open the exhaust port and the liquid discharge port to collect the natural gas and water obtained from the experimental decomposition, and simultaneously inject pure water of the second preheating temperature into the injection and production well simulation pipe. The data acquisition and analysis system 11 collects the decomposition data of the natural gas hydrate in real time. After the natural gas discharge is completed, the data acquisition and analysis system 11 saves and analyzes the collected data.

[0073] S13, open the exhaust port and the liquid discharge port, collect the natural gas and water obtained from the experimental decomposition, set the temperature control system to the second preheating temperature to heat the kettle body 504, and the data acquisition and analysis system 11 collects the decomposition data of the natural gas hydrate in real time. After the natural gas is discharged, the data acquisition and analysis system 11 saves and analyzes the collected data.

[0074] In this embodiment, in order to simulate the accumulation process of natural gas hydrates under different environments, two different base sand ratios and experimental schemes are designed under frozen soil conditions and marine conditions.

[0075] (I) The base sand ratio and experimental scheme under frozen soil conditions are as follows:

[0076] A. Prepare five kinds of quartz sand with different mesh sizes in advance, namely: quartz sand with a particle size less than 0.125mm, quartz sand with a particle size of 0.125mm-0.15mm; quartz sand with a particle size of 0.15mm-0.2mm; quartz sand with a particle size of 0.2mm-0.3mm and quartz sand with a particle size greater than 0.3mm; pre-prepared sodium chloride solution with a mass concentration of 3.35%; natural sodium-based bentonite is used as a regulator. According to the results of the orthogonal experiment, the different particle size ratios of the base sand are obtained: 5% of quartz sand below 60 mesh + 20% of quartz sand of 60-80 mesh + 30% of quartz sand of 80-100 mesh + 40% of quartz sand of 100-120 mesh + 5% of quartz sand above 120 mesh; and (4.5g / 40g base sand) natural sodium-based bentonite. The sediment layer in the reactor 50 is mainly composed of a mixture of 4kg of sodium chloride solution, 40kg of quartz sand of different particle sizes, and 4.5kg of natural nano-bentonite. Prepare the mixed glue solution for filling the space between the partition 503 and the reactor cover in advance, and prepare epoxy resin E-51, curing agent 650 and curing agent 201. First, stir and mix the curing agent 650 and the curing agent 201 in a mass ratio of 6:4 to form a composite curing agent. Then mix the composite curing agent and epoxy resin E-51 in a mass ratio of 1:3, let it stand, degas, and obtain the glue solution required for the experiment;

[0077] B. After ensuring that the top cover 501 is closed and all other valves are closed at the same time, open the liquid inlet 5011, open the second regulating valve 8, the second check valve 6 and the first booster pump 7, and continuously inject pure water into the kettle through the liquid inlet 5011 and the injection well. At the same time, start the data acquisition system to observe the pressure change in the reactor 50. When the pressure in the reactor reaches 15MPa, close the second regulating valve 8, the second check valve 6 and the first booster pump 7, stop injecting pure water, and keep the entire reactor sealed for 48 hours. Observe the pressure change in the reactor. After confirming that the reactor 50 is well sealed, open the first regulating valve, the third regulating valve, the first check valve and the third check valve to relieve the pressure in the reactor. At the same time, open the sixth regulating valve, the seventh regulating valve, the sixth check valve and the seventh check valve, and open the liquid outlet of the device to discharge all the water in the reactor.

[0078] C. Place the prepared injection and production well simulation pipe in the center of the kettle, preset the injection and production well position, put the assembled sensor 55 and the wiring pipeline into the kettle, and then fill the configured quartz sand into the reactor 50 layer by layer. Determine a point every 90° at a radius of 250mm and 200mm from the bottom of the kettle, and arrange 4 symmetrical points. Place a temperature sensor, a pressure sensor and a water saturation sensor at each point. After arranging the sensor 55, continue to fill the quartz sand layer by layer. During the filling process, continuously compact the sedimentary layer to ensure that the reactor 50 is filled densely, and the longitudinal Place the sensor 55 again at every 200mm distance, then repeat the above steps, place the four-layer sensor unit, fill the reactor 50 with quartz sand, then take out the injection and production well simulation tube, insert the injection and production well simulation tube into the reactor body 504 from the liquid outlet, place the partition 503 on the top of the reactor 50 after the injection and production well simulation tube is placed, and connect the wiring pipeline with the second through hole 5032 of the partition 503, pass the data acquisition line through the partition 503, integrate the data acquisition line, pass the integrated data acquisition line through the wiring port 5014 on the top cover 501, and then seal the top cover 501;

[0079] D. After sealing the top cover 501, the prefabricated glue is melted and injected into the gap between the partition 503 and the top cover 501 through the glue injection port 5013 on the top cover 501. During this period, hot water is introduced into the high-temperature spiral tube 49 to increase the ambient temperature in the kettle and prolong the solidification time of the glue. When the glue overflows from another glue injection port 5013, it means that the glue has filled the gap between the partition 503 and the kettle cover. Then, the high-temperature spiral tube 49 is closed and the glue is solidified at room temperature for 12 hours. After solidification, the environment in the kettle is heated to 338.15K through the high-temperature spiral tube 49 and the temperature is kept constant for another 4 hours of solidification. Finally, it is cooled to form the glue filling layer required for the experiment to ensure that the pressure strength between the partition 503 and the gap meets the experimental standard.

[0080] E. After the above-mentioned device is ready, the synthesis process of the hydrate is simulated, the first regulating valve, the third regulating valve 15 and the first check valve and the third check valve are opened, and then the first vacuum pump 3 and the second vacuum pump 14 are opened to exhaust all the air in the kettle to form a negative pressure environment in the kettle. When the required negative pressure environment is reached in the kettle, the first regulating valve 2, the third regulating valve 15 and the first check valve and the third check valve 13 are closed;

[0081] F. Ensure that all valves are in a closed state, then open the eighth regulating valve 37, the eighth check valve 35 and the first gas compressor 36, and at the same time open the main valve 34, and continuously inject nitrogen into the reactor 50 until the reactor is filled with nitrogen and the pressure in the reactor reaches 8MPa, then close the first gas compressor 36 and all valves, and after the reactor 50 is stable, let it stand for 8 hours, and observe the pressure change of the reactor 50. If there is any leakage of gas in the reactor 50, check the leakage location, exhaust all the gas, tighten the valve, and repeat the above operation until there is no pressure change within 8 hours;

[0082] G. After ensuring the air tightness of the device, open the water inlet to inject pure water into the kettle, open the second regulating valve 8 and the second check valve 6, and open the first regulating valve, the third regulating valve and the first check valve, the third check valve at the same time, open the first booster pump 7 to continuously inject pure water of about 274.15K into the kettle until the kettle is completely filled, and discharge all the nitrogen in the kettle. When all the nitrogen is discharged, close all valves, let the reactor 50 stand for 2 hours to ensure that the reactor 50 is relatively stable, and start the low-temperature spiral tube 48 to provide ambient temperature, open the tenth and eleventh check valves 51, the tenth regulating valve, the eleventh regulating valve, the fifth liquid constant flow pump and the second liquid booster pump, and continuously inject 274.15K water into the low-temperature spiral tube 48 to maintain the temperature in the kettle stable;

[0083] H. After the above operations are completed and the kettle is kept relatively stable for a period of time, the seventh regulating valve 31, the sixth regulating valve, the seventh check valve, and the sixth check valve 25 are opened, and the ninth regulating valve 42 and the ninth check valve 40 are opened at the same time, and the main valve 34 is opened to start the second gas compressor 41 and the first liquid constant flow pump 28 and the second liquid constant flow pump 29, and methane gas is slowly injected into the reactor 50, and the excess pure water in the reactor is slowly driven out by methane gas until the reactor 50 is filled with methane gas and the pressure reaches above 6MPa, and all valves are closed, and the natural gas hydrate synthesis reaction begins;

[0084] I. During the natural gas hydrate synthesis process, methane gas is continuously injected into the kettle to a pressure of 12 MPa, and at the same time, the fourth regulating valve 18, the fourth check valve 20, the fifth regulating valve 21, and the fifth check valve 23 are opened, and the spiral hot water pipe is opened and the pure water in the high-temperature spiral pipe 49 is heated through the high-temperature water tank 17, so that the temperature in the kettle is stably maintained at about 280.15 K. At the same time, the first centrifugal pump 19 and the second centrifugal pump 22 are opened to allow the pure water in the high-temperature spiral pipe 49 to flow, thereby improving the heat exchange efficiency. During this process, the pressure is maintained at about 10 MPa to simulate the reservoir conditions of hydrates in a frozen soil environment;

[0085] J. After the pressure in the kettle reaches equilibrium, perform a gas replenishment operation to increase the gas pressure in the kettle to above 6MPa to ensure that hydrates can be fully generated. At this time, bound water is generated in the pores of the quartz sand. After the temperature and pressure remain stable for 48 hours, the hydrate synthesis process is considered to be completed;

[0086] K. When the synthesis of natural gas hydrate is completed, observe the data measured by the sensor 55. If it is found that the longitudinal measurement data of the sensor 55 have a large difference, immediately terminate the experiment, refill the quartz sand and sodium chloride solution and repeat the above synthesis-related steps until the longitudinal difference of the data measured by the sensor 55 is within the allowable error range.

[0087] L. Ensure that hydrates have been synthesized in the above process, and then simulate the hydrate extraction process. The following extraction operation process will take the heat injection method and heating method as examples.

[0088] (1) (Heat injection method) Open the first regulating valve 2, the first vacuum pump 3, the first check valve 4, the third check valve 13, the second vacuum pump 14, and the third regulating valve 15 of the gas outlet 5012, and open the sixth check valve 25, the seventh check valve 32, the sixth regulating valve 26, the first liquid constant flow pump 28, the second liquid constant flow pump 29, the seventh regulating valve 31, and the seventh check valve 32 of the liquid outlet, and prepare to collect the natural gas and water obtained by the experimental decomposition. Open the second check valve 6, the first booster pump 7, and the second regulating valve 8 of the liquid inlet 5011, and inject 343.5K pure water into the injection and production well simulation pipe. The data acquisition system collects the natural gas hydrate decomposition data in real time. When the measured values ​​of the first gas flow meter 5 and the second gas flow meter 12 no longer change, it is determined that the natural gas hydrate decomposition is completed, and the collected data is saved and analyzed.

[0089] (2) (Heating method) Close the tenth check valve 45, the third centrifugal pump 46, the tenth regulating valve 47, the eleventh check valve 51, the fourth centrifugal pump 52, and the eleventh regulating valve 53 of the low-temperature spiral tube 48, and prepare to perform the heating method. Open the first regulating valve 2, the first vacuum pump 3, the first check valve 4, the third check valve 13, the second vacuum pump 14, and the third regulating valve 15 of the gas outlet 5012, and open the sixth check valve 25, the seventh check valve 32, the sixth regulating valve 26, the first liquid constant flow pump 28, the second liquid constant flow pump 29, the seventh regulating valve 31, and the seventh check valve 32 of the liquid outlet, and prepare to collect the natural gas and water obtained by the experimental decomposition. 343.5K pure water is continuously introduced into the high-temperature spiral tube 49, and the data acquisition system collects the decomposition data of natural gas hydrate in real time. When the measured values ​​of the first gas flow meter 5 and the second gas flow meter 12 no longer change, it is determined that the decomposition of natural gas hydrate is completed, and the collected data is saved and analyzed.

[0090] (II) The base sand ratio and experimental scheme under marine conditions are as follows:

[0091] Five kinds of quartz sand with different mesh sizes are prepared in advance, namely: quartz sand with a particle size less than 0.1mm; quartz sand with a particle size of 0.1mm-0.2mm; quartz sand with a particle size of 0.2mm-0.3mm; quartz sand with a particle size of 0.3mm-0.35mm; quartz sand with a particle size greater than 0.35mm; a pre-configured sodium chloride solution with a mass concentration of 3.5%; and natural sodium-based bentonite as a regulator. According to the orthogonal test results, the ratio of different particle sizes of base sand is obtained: 5% of quartz sand below 45 mesh + 15% of quartz sand of 45-60 mesh + 35% of quartz sand of 60-80 mesh + 40% of quartz sand of 80-150 mesh + 5% of quartz sand above 150 mesh and (2.8g / 40g base sand) natural sodium-based bentonite; the sediment layer in the reactor 50 is mainly composed of a mixture of 4kg of sodium chloride solution, 40kg of quartz sand of different particle sizes and 4.5kg of natural sodium-based bentonite fully mixed; the mixed glue liquid for filling the space between the partition 503 and the reactor cover is prepared in advance, and epoxy resin E-51, curing agent 650 and curing agent 201 are prepared. First, the curing agent 650 and the curing agent 201 are stirred and mixed in a mass ratio of 6:4 to prepare a composite curing agent. Then the composite curing agent is mixed with the epoxy resin E-51 in a mass ratio of 1:3, and the mixture is allowed to stand and deaerated to obtain the glue liquid required for the experiment.

[0092] B. Ensure that the top cover 501 is closed and all other valves are closed at the same time, open the liquid inlet 5011, open the second regulating valve 8, the second check valve 6 and the first booster pump 7, and continuously inject pure water into the kettle through the liquid inlet 5011 and the injection and production well simulation pipe. At the same time, start the data acquisition system to observe the pressure change in the reactor 50. When the pressure in the reactor reaches 15MPa, close the second regulating valve 8, the second check valve 6 and the first booster pump 7, stop injecting pure water, and keep the whole reactor sealed for 48 hours. Observe the pressure change in the reactor. After confirming that the reactor 50 is well sealed, open the first regulating valve, the third regulating valve, the first check valve and the third check valve to relieve the pressure in the reactor. At the same time, open the sixth regulating valve, the seventh regulating valve, the sixth check valve and the seventh check valve, and open the liquid outlet to discharge all the water in the reactor.

[0093] C. Place the prepared injection and production well simulation pipe in the center of the reactor, preset the injection and production well position, put the assembled sensor 55 and the wiring pipeline into the reactor, and then fill the configured quartz sand into the reactor 50 layer by layer. Determine a point every 90° at a radius of 250mm and 200mm from the bottom of the reactor, and arrange 4 symmetrical points. Place a temperature sensor, a pressure sensor and a water saturation sensor at each point. After arranging the sensor unit, continue to fill the quartz sand layer by layer. During the filling process, continuously compact the sediment layer to ensure that the reactor 50 is filled relatively tightly. Dense, place the sensor unit again at every 200mm distance in the longitudinal direction, then repeat the above steps, place the four layers of sensor units, the reactor 50 is filled with quartz sand, then take out the injection and production well simulation tube, place the injection and production well simulation tube in the preset position, place the partition 503 on the top of the reactor 50 after the injection and production well simulation tube is placed, and connect the wiring pipeline with the second through hole 5032 of the partition 503, pass the data acquisition line through the partition 503, integrate the data acquisition line, pass the integrated data acquisition line through the wiring port 5014 on the top cover 501, and then seal the reactor cover;

[0094] D. After sealing the top cover 501, the prefabricated glue is melted and injected into the gap between the partition 503 and the top cover 501 through the glue injection port 5013 on the top cover 501. During this period, hot water is introduced into the high-temperature spiral tube 49 to increase the ambient temperature in the kettle and prolong the solidification time of the glue. When the glue overflows from another glue injection port 5013, it means that the glue has filled the gap between the partition 503 and the top cover 501. Then close the Gaoen spiral tube and keep the glue at room temperature for 12 hours to solidify. After solidification, heat the environment in the kettle to 338.15K through the high-temperature spiral tube 49 and keep the constant temperature for another 4 hours to solidify. Finally, cool to form the glue filling layer required for the experiment to ensure that the pressure strength between the partition 503 and the gap meets the experimental standard.

[0095] E. After the above-mentioned device is ready, the synthesis process of the hydrate is simulated, the first regulating valve, the third regulating valve 15 and the first check valve and the third check valve are opened, and then the first vacuum pump 3 and the second vacuum pump 14 are opened to exhaust all the air in the kettle to form a negative pressure environment in the kettle. When the required negative pressure environment is reached in the kettle, the first regulating valve, the third regulating valve 15 and the first check valve and the third check valve 13 are closed;

[0096] F. Ensure that all valves are in a closed state, then open the eighth regulating valve 37, the eighth check valve 35 and the first gas compressor 36, and at the same time open the main valve 34, and continuously inject nitrogen into the reactor 50 until the reactor is filled with nitrogen and the pressure in the reactor reaches 8MPa, then close the first gas compressor 36 and all valves, and after the reactor 50 is stable, let it stand for 8 hours, and observe the pressure change of the reactor 50. If there is any leakage of gas in the reactor 50, check the leakage location, exhaust all the gas, tighten the valve, and repeat the above operation until there is no pressure change within 8 hours;

[0097] G. After ensuring the air tightness of the device, open the water inlet to inject pure water into the kettle, open the second regulating valve 8 and the second check valve 6, and open the first regulating valve, the third regulating valve and the first check valve, the third check valve at the same time, and open the first booster pump 7 to continuously inject pure water of about 274.15K into the kettle until the kettle is completely filled, and discharge all the nitrogen in the kettle. When all the nitrogen is discharged, close all valves and let the reactor stand for 50 to 2 hours to ensure that the reactor 50 is relatively stable. At the same time, start the low-temperature spiral tube 48 to provide ambient temperature, open the tenth and eleventh check valves 51, the tenth regulating valve, the eleventh regulating valve, the fifth liquid constant flow pump and the second liquid booster pump, and continuously inject 274.15K water into the low-temperature spiral water tube to maintain the temperature in the kettle stable;

[0098] H. After the above operations are completed and the kettle is kept relatively stable for a period of time, the seventh regulating valve 31, the sixth regulating valve, the seventh check valve, and the sixth check valve 25 are opened, and the ninth regulating valve 42 and the ninth check valve 40 are opened at the same time, and the main valve 34 is opened to start the second gas compressor 41 and the first liquid constant flow pump 28 and the second liquid constant flow pump 29, and methane gas is slowly injected into the reactor 50, and the excess pure water in the reactor is slowly driven out by methane gas until the reactor 50 is filled with methane gas and the pressure reaches above 6MPa, and all valves are closed, and the natural gas hydrate synthesis reaction begins;

[0099] I. During the natural gas hydrate synthesis process, methane gas is continuously injected into the kettle to a pressure of 12 MPa, and at the same time, the fourth regulating valve 18, the fourth check valve 20, the fifth regulating valve 21, and the fifth check valve 23 are opened, the high-temperature spiral tube 49 is opened, and the pure water in the high-temperature spiral tube 49 is heated by the high-temperature water tank 17, so that the temperature in the kettle is stably maintained at about 285.15 K, and at the same time, the first centrifugal pump 19 and the second centrifugal pump 22 are opened to allow the pure water in the high-temperature spiral tube 49 to flow, thereby improving the heat exchange efficiency. During this process, the pressure is maintained at about 12 MPa to simulate the reservoir conditions of hydrates in a frozen soil environment;

[0100] J. After the pressure in the kettle reaches equilibrium, perform a gas replenishment operation to increase the gas pressure in the kettle to above 6MPa to ensure that hydrates can be fully generated. At this time, bound water is generated in the pores of the quartz sand. After the temperature and pressure remain stable for 48 hours, the hydrate synthesis process is considered to be completed;

[0101] K. Observe the data measured by the sensor 55 when the synthesis of natural gas hydrate is completed. If it is observed that the longitudinal difference of the measured data of the sensor 55 is large, immediately terminate the experiment, refill the quartz sand and sodium chloride solution and repeat the above synthesis-related steps until the longitudinal difference of the measured data of the sensor 55 is within the allowable error range;

[0102] L. Ensure that the hydrate has been synthesized in the above process, and then simulate the hydrate extraction process. The following extraction operation process will take the heat injection method and the heating method as examples;

[0103] (1) (Heat injection method) Open the first regulating valve 2, the first vacuum pump 3, the first check valve 4, the third check valve 13, the second vacuum pump 14, and the third regulating valve 15 of the gas outlet 5012, and open the sixth check valve 25, the seventh check valve 32, the sixth regulating valve 26, the first liquid constant flow pump 28, the second liquid constant flow pump 29, the seventh regulating valve 31, and the seventh check valve 32 of the liquid outlet, and prepare to collect the natural gas and water obtained by the experimental decomposition. Open the second check valve 6, the first booster pump 7, and the second regulating valve 8 of the liquid inlet 5011, and inject 343.5K pure water into the injection and production well simulation pipe. The data acquisition system collects the natural gas hydrate decomposition data in real time. When the measured values ​​of the first gas flow meter 5 and the second gas flow meter 12 no longer change, it is determined that the natural gas hydrate decomposition is completed, and the collected data is saved and analyzed.

[0104] (2) (Heating method) Close the tenth check valve 45, the third centrifugal pump 46, the tenth regulating valve 47, the eleventh check valve 51, the fourth centrifugal pump 52, and the eleventh regulating valve 53 of the low-temperature spiral tube 48 to prepare for the heating method; open the first regulating valve 2, the first vacuum pump 3, the first check valve 4, the third check valve 13, the second vacuum pump 14, and the third regulating valve 15 of the gas outlet 5012, and open the sixth check valve 25, the seventh check valve 32, the sixth regulating valve 26, the first liquid constant flow pump 28, the second liquid constant flow pump 29, the seventh regulating valve 31, and the seventh check valve 32 of the liquid outlet to prepare for collecting the natural gas and water obtained by the experimental decomposition. 343.5K pure water is continuously introduced into the high-temperature spiral tube 49, and the data acquisition system collects the decomposition data of natural gas hydrate in real time. When the measured values ​​of the first gas flow meter 5 and the second gas flow meter 12 no longer change, it is determined that the decomposition of natural gas hydrate is completed, and the collected data is saved and analyzed.

[0105] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0106] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A large-scale natural gas hydrate development simulation device, characterized in that: The invention comprises an injection-production well simulation pipe, a reactor, a gas supply system connected with the reactor and providing gas to the reactor, a liquid supply system connected with the reactor and providing liquid to the reactor, a gas collection system connected with the reactor and used for collecting gas generated by the reactor during experiments, a liquid collection system connected with the reactor and used for collecting liquid generated by the reactor during experiments, a temperature control system for controlling the temperature of the reactor, and a data acquisition and analysis system for collecting experimental data, wherein the data acquisition and analysis system comprises a plurality of layers of sensor units arranged in the reactor body at intervals along the axial direction of the reactor, each layer of the sensor units comprises a plurality of groups of sensors evenly spaced along the circumference of the reactor body, and each group of the sensors comprises a temperature sensor, a pressure sensor and a water saturation sensor.

2. The large-scale natural gas hydrate development simulation device according to claim 1, characterized in that: The temperature control system includes a low-temperature water tank, a high-temperature water tank, and a double helical tube wound around the outer wall of the kettle body, wherein the double helical tube includes a low-temperature helical tube connected to the low-temperature water tank and a high-temperature helical tube connected to the high-temperature water tank.

3. The large-scale natural gas hydrate development simulation device according to claim 2, characterized in that: The low-temperature spiral tube and the high-temperature spiral tube are both wrapped with a thermal insulation layer.

4. The large-scale natural gas hydrate development simulation device according to any one of claims 1 to 3, characterized in that: The reactor also includes a top cover and a bottom cover respectively arranged at both ends of the reactor body, and a partition arranged in the reactor body, the partition is provided with a plurality of first through holes for the data transmission line of the sensor to pass through and a second through hole for the injection and production well simulation pipe to pass through, the top cover has a liquid inlet, an air outlet, a glue injection port, and a wiring port for integrating the data transmission line, and the bottom cover is provided with an air inlet and a liquid outlet.

5. The large-scale natural gas hydrate development simulation device according to claim 4, characterized in that: The air supply system includes an air supply device, an air intake pipe with two ends respectively connected to the air supply device and the air inlet, and the air intake pipe is sequentially connected to an air intake flow meter, an air intake regulating valve, an air intake compressor and an air intake check valve.

6. The large-scale natural gas hydrate development simulation device according to claim 4, characterized in that: The liquid supply system comprises a liquid supply device, a liquid inlet pipeline whose two ends are respectively connected to the liquid supply device and the liquid inlet, and the liquid inlet pipeline is sequentially connected to a liquid inlet flow meter, a liquid inlet check valve, a booster pump and a liquid inlet regulating valve.

7. The large-scale natural gas hydrate development simulation device according to claim 4, characterized in that: It also includes a booster gas compressor. The gas collection system includes a gas collecting device, and an outlet pipe whose two ends are respectively connected to the gas collecting device and the outlet. The outlet pipe is connected with an outlet regulating valve, a vacuum pump, an outlet check valve and an outlet flow meter in sequence, and the booster gas compressor is connected to the outlet pipe.

8. The large-scale natural gas hydrate development simulation device according to claim 4, characterized in that: The liquid collection system includes a liquid collecting device, a liquid outlet pipe with two ends respectively connected to the liquid collecting device and the liquid outlet, and the liquid outlet pipe is sequentially connected to a liquid outlet regulating valve, a liquid constant flow pump, a liquid outlet check valve and a liquid outlet flow meter.

9. An experimental method for a large-scale natural gas hydrate development simulation device according to any one of claims 4 to 8, characterized in that: The following steps are involved: S1. According to the base sand ratio scheme, a mixture including sodium chloride solution, quartz sand of different mesh sizes and natural sodium-based bentonite is prepared; S2, inserting the injection and production well simulation pipe into the axis position of the reactor, laying the mixture layer by layer according to the preset position of each layer of the sensor unit, after laying each layer of the mixture, first arrange the sensor units of the corresponding layer, and then lay the next layer of the mixture, until all the sensor units are arranged, and finally fill the kettle with the mixture, and pull out the injection and production well simulation pipe, insert the injection and production well simulation pipe into the reactor from the liquid inlet, place the partition on the mixture, the data transmission line of the sensor unit passes through the partition and is integrated, the integrated data transmission line passes through the wiring port, and the top cover is sealed on the kettle; S3, injecting glue liquid through the glue injection port so that the glue liquid fills between the partition plate and the top cover, and through the temperature control of the temperature control system, the glue liquid forms a colloid filling layer required for the experiment; S4, only opening the exhaust port to exhaust all the air in the kettle body, and closing the exhaust port after a negative pressure environment is formed in the kettle body; S5, opening the air inlet, injecting nitrogen into the reactor, filling the reactor with nitrogen and making the pressure inside the reactor reach a first preset pressure value, closing the air inlet, and leaving the reactor to stand for a first preset time; if the pressure inside the reactor does not change within the first preset time, executing step S6; if the pressure inside the reactor changes within the first preset time, checking the gas leakage location and repairing it, exhausting all the gas, and repeating step S5; S6, opening the liquid inlet, injecting pure water into the reactor until the reactor is filled, opening the exhaust port, exhausting all the nitrogen, closing the exhaust port, allowing the reactor to stand for a second preset time, and during the second preset time, opening the temperature control system to keep the temperature in the reactor stable; S7, opening the air inlet, injecting methane gas into the reactor, and opening the drain port to discharge excess pure water in the reactor body, until the reactor is filled with methane gas and the pressure in the reactor reaches a second preset pressure value or higher, closing the drain port, and starting the natural gas hydrate synthesis reaction; S8. During the natural hydrate synthesis process, continuously injecting methane gas into the reactor to make the pressure in the reactor reach a third preset pressure value, closing the air inlet, and opening the temperature control system to keep the temperature in the reactor within the first preset temperature value; S9, after the pressure in the kettle body is stable, open the air inlet, inject methane gas into the reactor and make the pressure in the reactor reach above the second preset pressure value, and after the temperature and pressure in the reactor body remain stable for a third preset time, the synthesis process of natural gas hydrate is completed; S10, observing the data measured by the sensor units, if the difference between the measured data of the sensor units of two adjacent layers is within the preset value range, executing step S11; if the difference between the measured data of the sensor units of two adjacent layers exceeds the preset value, terminating the experiment and re-executing steps S2 to S9; S11, if the natural gas hydrate is mined by the heat injection method, then execute step S12; if the natural gas hydrate is mined by the heating method, then execute step S13; S12. Open the exhaust port and the liquid discharge port to collect the natural gas and water obtained from the experimental decomposition, and simultaneously inject pure water of the second preheating temperature into the injection-production well simulation pipe. The data acquisition and analysis system collects the decomposition data of the natural gas hydrate in real time. After the natural gas discharge is completed, the data acquisition and analysis system saves and analyzes the collected data. S13, opening the exhaust port and the liquid discharge port, collecting the natural gas and water obtained from the experimental decomposition, setting the temperature control system to a second preheating temperature to heat the kettle body, and the data acquisition and analysis system collecting the decomposition data of the natural gas hydrate in real time, and after the natural gas is discharged, the data acquisition and analysis system saves and analyzes the collected data.

10. The experimental method of the large-scale natural gas hydrate development simulation device according to claim 9, characterized in that: In step S3, there are two glue injection ports, and the glue liquid is injected from one of the glue injection ports, and the kettle body is heated by the temperature control system. When the glue liquid overflows from the other glue injection port, the temperature control system stops heating the kettle body. After the glue liquid is allowed to stand for a fourth preset time, the kettle body is heated to a third preheating temperature by the temperature control system and maintained at a constant temperature for a fifth preset time, and then the temperature control system is turned off to allow the glue liquid to cool to form a glue filling layer required for the experiment.

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