Water flow erosion method natural gas hydrate exploitation experiment simulation method and device
Technical Field
The invention belongs to the technical field of marine natural gas hydrate exploitation, and particularly relates to a method and a device for simulating a natural gas hydrate exploitation experiment by a water flow erosion method.
Background
The natural gas hydrate is used as a new alternative energy, has the characteristics of high energy density, large reserve, sustainability, environmental friendliness and the like, and has a wide exploitation and development prospect. The exploitation of the natural gas hydrate can effectively change the energy consumption structure of China, and has important significance for the development of the energy industry of China. Natural gas hydrate, as an unstable complex of water and natural gas, is only formed below phase equilibrium. The factors influencing the natural gas hydrate phase equilibrium mainly include: chemical potential, temperature, pressure, etc., and the natural gas hydrates decompose upon a change in certain conditions therein. At present, the most widely studied worldwide is the depressurization exploitation method, and the method has the characteristics of simplicity, economy, effectiveness and the like. But the disadvantages of the pressure reduction mining method are also obvious. Compared with pressure reduction exploitation, the current water flow erosion method can well solve and avoid the existing problems, and is also an important method for future hydrate exploitation. The water flow erosion method solves the problems existing in other mining methods: the method solves the problems that in the hydrate exploitation of other methods, due to the fact that a large amount of hydrates are decomposed and absorb heat, and the reservoir temperature suddenly drops caused by pressure increase, flow acceleration and the like caused by a large amount of gas, the formation is frozen, secondary hydrates are generated, the reservoir permeability is reduced, and the exploitation efficiency and safety are affected. Secondly, the method comprises the following steps: the problem that the gas production efficiency is extremely low in the later stage of hydrate exploitation by other methods is solved. And thirdly, the problems that due to other mining methods, the hydrate is decomposed very fast, the strength of the bottom layer is suddenly reduced, the bottom layer is unstable, and unnecessary natural disasters are caused are solved.
Aiming at the defects of the existing hydrate exploitation process, the invention provides a water flow erosion method natural gas hydrate exploitation experimental simulation method and a water flow erosion method natural gas hydrate exploitation experimental simulation device.
Disclosure of Invention
The invention provides a simulation method and a device for a natural gas hydrate exploitation experiment by a water flow erosion method, aiming at the defects in the existing hydrate exploitation process, based on the influence of water flow on the stability of the hydrate, the decomposition of the hydrate caused by the chemical potential difference between a hydrate phase and an environmental water phase in the water flow process and the influence of the water flow speed on the decomposition speed of the hydrate, and combining other hydrate development methods such as a depressurization exploitation method and a heat injection exploitation method. Provides basis for realizing safe and efficient exploitation of the hydrate.
The technical scheme of the invention is as follows:
a water flow erosion method natural gas hydrate exploitation experiment simulation device comprises a generation reaction system, an injection system, a separation and collection system and a detection and data acquisition system;
the generation reaction system comprises a reaction kettle 3, a sandy soil filter 10 and a first constant-temperature water bath 13-1; the reaction kettle 3 is arranged in the first constant-temperature water bath 13-1, the reaction kettle 3 is a cylinder with boss structures at two ends, axial flow of hydrates is convenient to realize, the reaction kettle is used for generating natural gas hydrates, and a natural gas hydrate reservoir stratum is simulated; the sand filter 10 is provided with two sand filters which are respectively connected with two ends of the reaction kettle 3, so that sand leakage in the generation process and the water flowing process is prevented, pipelines are blocked, and the measurement of experimental results is influenced; the first constant-temperature water bath 13-1 provides a stable low-temperature environment for the generation of the hydrate;
the injection system comprises a high-precision air injection pump 1-1, a high-precision water injection pump 1-2, an air source 2, a first one-way needle valve 12-1, a second one-way needle valve 12-2, a third one-way needle valve 12-3, a fourth one-way needle valve 12-4 and a second constant-temperature water bath 13-2; the gas source 2 enters the high-precision gas injection pump 1-1 through a first one-way needle valve 12-1; the high-precision air injection pump 1-1 and the high-precision water injection pump 1-2 are respectively gathered in a fourth one-way needle valve 12-4 through a second one-way needle valve 12-2 and a third one-way needle valve 12-3 and then connected with the inlet end of the reaction kettle 3; water required by hydrate generation is provided by a high-precision water injection pump 1-2, and methane gas required by hydrate generation is provided by the high-precision air injection pump 1-1; the second constant-temperature water bath 13-2 provides constant temperature conditions for the high-precision air injection pump 1-1 and the high-precision water injection pump 1-2; after the hydrate is generated, the temperature of water in the high-precision water injection pump 1-2 is changed by adjusting the second constant-temperature water bath 13-2, and the water is continuously injected into the reaction kettle 3 by utilizing the pressure and speed adjusting mode of the pump;
the separation and collection system comprises a gas-water separation device 4, a high-precision back pressure pump 1-3, a back pressure valve 6, a circulating water pump 15, a fifth one-way needle valve 12-5, a sixth one-way needle valve 12-6, a seventh one-way needle valve 12-7, an eighth one-way needle valve 12-8 and a ninth one-way needle valve 12-9; the gas-water separation device 4 is a water jacket circulation cooling type device, an externally embedded water jacket is wrapped outside the gas-water separation device 4, water recycling in the water flow experiment process is realized through external water bath circulation, and a gas-water inlet of the gas-water separation device 4 is connected to the outlet of the reaction kettle 3 through a fifth one-way needle valve 12-5 and used for separating water and decomposed gas generated by the decomposition of hydrates in the water flow erosion process; two ends of the circulating water pump 15 are respectively connected to a water outlet of the gas-water separation device 4 and an inlet of the reaction kettle 3 through an eighth one-way needle valve 12-8 and a ninth one-way needle valve 12-9, so that water recycling in the experimental process is realized; the high-precision back pressure pump 1-3 is connected to a water outlet of the gas-water separation device 4 through a sixth one-way needle valve 12-6 and is used for controlling the pressure in the reaction kettle 3 in the experimental process and simultaneously taking the produced water in the water flowing process, so that the calculation is facilitated; the back pressure valve 6 is connected with the air outlet of the gas-water separation device 4 through a seventh one-way needle valve 12-7; when continuous water flows, the high-precision back pressure pumps 1-3 and the back pressure valve 6 are adjusted to the pressure in the reaction kettle 3, so that the influence of temperature and pressure change in the mining process is eliminated;
the detection and data acquisition system comprises a high-precision temperature sensor 11, a high-precision inlet pressure sensor 9, a high-precision outlet pressure sensor 14, a high-precision gas flowmeter 5, a data acquisition module 8 and an information acquisition and storage system 7; the high-precision pressure sensor 9 and the high-precision outlet pressure sensor 14 are respectively connected with the sandy soil filter 10 and used for acquiring the internal pressure change condition of the reaction kettle 3 and the pressure change conditions of the inlet and the outlet of the reaction kettle 3 in the water flowing process to obtain pressure difference data; the high-precision temperature sensors 11 are arranged in the reactor body of the reaction kettle 3 at equal intervals along the axial direction of the reaction kettle 3 and are used for acquiring the temperature change in the reaction kettle 3 in the hydrate generation process and the water flowing process; one end of the data acquisition module 8 is connected with the high-precision temperature sensor 11, and the other end of the data acquisition module is connected with the information acquisition and storage system 7; the information acquisition and storage system 7 is also connected with the back pressure valve 6; the temperature and pressure signals obtained by the high-precision temperature sensor 11 and the high-precision pressure sensor 9 are converted into digital signals through the data acquisition module 8 and are stored and displayed in the information acquisition and storage system 7; the high-precision gas flowmeter 5 is connected between the gas-water separation device 4 and the back pressure valve 6, and controls the gas flow through a seventh one-way needle valve 12-7; before the continuous water flow starts, a back pressure valve 6 is opened and the back pressure is adjusted, then a seventh one-way needle valve 12-7 is opened to realize pressure maintaining in the water flow process, and the gas production is recorded through a high-precision gas flowmeter 5.
A water flow erosion method natural gas hydrate exploitation experiment simulation method comprises the following steps:
(1) and (4) checking: all valves and pumps are closed, so that all devices and pipelines are ensured to be watertight and airtight;
(2) hydrate generation: obtaining the required water volume and sand volume by calculating the saturation of the initial hydrate, and uniformly and compactly filling the glass sand or clay into the reaction kettle 3; opening a third one-way needle valve 12-3 and a fourth one-way needle valve 12-4, and uniformly injecting deionized water with required volume; opening the first one-way needle valve 12-1, and performing gas supplement on the high-precision gas injection pump 1-1 through the gas source 2; after the supplement is finished, closing the first one-way needle valve 12-1, opening the second one-way needle valve 12-2 and the fourth one-way needle valve 12-4, uniformly injecting gas, setting the pressure of the high-precision gas injection pump 1-1 as a target pressure, and keeping a constant pressure state all the time; the temperature is kept by the constant temperature water bath 13-1 all the time in the hydrate generation process, and the temperature of the constant temperature water bath 13-1 is set as the target temperature; the temperature and pressure change in the experimental process is detected and recorded by a high-precision inlet pressure sensor 9, a high-precision outlet pressure sensor 14 and a high-precision temperature sensor 11;
(3) back pressure regulation: after the hydrate is generated, closing the second one-way needle valve 12-2 and the fourth one-way needle valve 12-4; setting the pressures of the high-precision back pressure pumps 1-3 and the back pressure valve 6 as experimental target pressures respectively, and opening a fifth one-way needle valve 12-5, a sixth one-way needle valve 12-6 and a seventh one-way needle valve 12-7 after the temperature is stable; filling the high-precision water injection pump 1-2 with water, setting the pressure of the high-precision water injection pump to be higher than the experimental target pressure, and realizing the water flowing process in the system through differential pressure;
(4) the water flowing process: when the pressure of the whole experiment system is stable, opening a fourth one-way needle valve 12-4 to perform a water flow experiment; when water flows out from the water outlet of the gas-water separator 4 and a certain amount of water is stored to maintain the whole water flow process, closing the fourth one-way needle valve 12-4, opening the eighth one-way needle valve 12-8, the ninth one-way needle valve 12-9 and the circulating water pump 15, adjusting the circulating speed of the circulating water pump 15 and realizing an automatic circulating flow decomposition experiment; in the whole water flow experiment process, the temperature and pressure changes are detected and recorded by a high-precision inlet pressure sensor 9, a high-precision outlet pressure sensor 14 and a high-precision temperature sensor 11 respectively; the decomposed gas and the flowing water in the water flowing process are separated by a gas-water separation device 4, the hydrate decomposed gas caused by the water flowing process is recorded by a high-precision flow meter 5, and the flowing water in the water flowing process is collected and recorded by a back pressure valve 6;
(5) signal acquisition-recording-processing: temperature and pressure signals in the whole experiment process are converted into data signals through the data acquisition module 8, and data are recorded and processed through the information acquisition and storage system 7.
The invention has the beneficial effects that: according to the research on hydrate stability in the water flowing process, a water flow erosion method natural gas hydrate exploitation experimental simulation method and a water flow erosion method natural gas hydrate exploitation experimental simulation device are provided by combining a depressurization exploitation method, a heat injection exploitation method and other hydrate exploitation methods. The method is used for realizing the water flow erosion method hydrate exploitation and the experimental research of the mutual combination of other methods. Reliable data support and theoretical analysis are provided for realizing efficient and safe commercial exploitation of the hydrate. Meanwhile, the method has important significance for the follow-up research of the natural gas hydrate exploitation method.
Drawings
FIG. 1 is a schematic diagram of the method and apparatus of the present invention.
In the figure: 1-1, a high-precision air injection pump; 1-2 high-precision water injection pumps; 1-3 high precision backpressure pumps; 2, gas source; 3, a reaction kettle; 4, a gas-water separation device; 5, a high-precision gas flowmeter; 6, a back pressure valve; 7, an information acquisition and storage system; 8, a data acquisition module; 9 high precision inlet pressure sensor; 10 a sandy soil filter; 11 high precision temperature sensor; 12-1 a first one-way needle valve; 12-2 second one-way needle valve; 12-3 a third one-way needle valve; 12-4 a fourth one-way needle valve; 12-5 a fifth one-way needle valve; 12-6 sixth one-way needle valve; 12-7 a seventh one-way needle valve; 12-8 eighth one-way needle valve; 12-9 ninth one-way needle valve; 13-1, first constant temperature water bath; 13-2, second constant-temperature water bath; 14 high precision outlet pressure sensor; 15 circulating the water pump.
Detailed Description
The following further describes the specific embodiments of the present invention with reference to the technical solutions and the accompanying drawings.
As shown in the figure, the device is connected according to the structure of the device, and the device is used for carrying out a hydrate exploitation experiment by a water flow erosion method and a method which is combined with other methods.
(1) And (4) checking: all valves and pumps are closed, so that all devices and pipelines are ensured to be watertight and airtight;
(2) hydrate generation: obtaining the required water volume and sand volume by calculating the saturation of the initial hydrate, and uniformly and compactly filling the glass sand or clay into the reaction kettle 3; opening a third one-way needle valve 12-3 and a fourth one-way needle valve 12-4, and uniformly injecting deionized water with required volume; opening a first one-way needle valve 12-1, and performing gas supplement on the high-precision gas injection pump through a gas source 2; after the supplement is finished, closing the first one-way needle valve 12-1, opening the second one-way needle valve 12-2 and the fourth one-way needle valve 12-4, uniformly injecting gas, setting the pressure of the high-precision gas injection pump 1-1 as a target pressure and keeping a constant pressure state all the time; the temperature is kept by the constant temperature water bath 13-1 all the time in the hydrate generation process, and the temperature of the constant temperature water bath 13-1 is set as the target temperature; the temperature and pressure change in the experimental process is detected and recorded by a high-precision inlet pressure sensor 9, a high-precision outlet pressure sensor 14 and a high-precision temperature sensor 11;
(3) back pressure regulation: after the hydrate is generated, closing the second one-way needle valve 12-2 and the fourth one-way needle valve 12-4; setting the pressures of the high-precision back pressure pump 1-3 and the back pressure valve 6 as experimental target pressures respectively, and opening a fifth one-way needle valve 12-5, a sixth one-way needle valve 12-6 and a seventh one-way needle valve 12-7 after the temperature is stable; filling the high-precision water injection pump 1-2 with water, setting the pressure of the high-precision water injection pump to be slightly higher than the experimental pressure, and realizing the water flowing process in the system through differential pressure;
(4) the water flowing process: when the pressure of the whole experiment system is stable, opening a fourth one-way needle valve 12-4 to perform a water flow experiment; when water flows out from the water outlet of the gas-water separator 4 and a certain amount of water is stored to maintain the whole water flow process, closing the fourth one-way needle valve 12-4, opening the eighth one-way needle valve 12-8, the ninth one-way needle valve 12-9 and the circulating pump 15, adjusting the circulating speed of the circulating pump, and realizing an automatic circulating flow decomposition experiment; in the whole water flow experiment process, the temperature and pressure changes are detected and recorded by a high-precision inlet pressure sensor 9, a high-precision outlet pressure sensor 14 and a high-precision temperature sensor 11 respectively; the decomposed gas and the flowing water in the water flowing process are separated by a gas-water separation device 4, the hydrate decomposed gas caused by the water flowing process is recorded by a high-precision flow meter 5, and the flowing water in the water flowing process is collected and recorded by a back pressure valve 6;
(5) signal acquisition-recording-processing: temperature and pressure signals in the whole experiment process are converted into data signals through the data acquisition module 8, and data are recorded and processed through the information acquisition and storage system 7.
The above examples are one of the specific embodiments of the present invention, and the general changes, substitutions and combinations made by those skilled in the art within the technical scope of the present invention are included in the protection scope of the present invention.