WO2017008354A1

WO2017008354A1 - Experimental device and experimental method for studying porous medium skeleton change in natural gas hydrate decomposition process

Info

Publication number: WO2017008354A1
Application number: PCT/CN2015/085928
Authority: WO
Inventors: 李小森; 王屹; 冯景春; 李刚; 张郁
Original assignee: 中国科学院广州能源研究所
Priority date: 2015-07-10
Filing date: 2015-08-03
Publication date: 2017-01-19
Also published as: CN105044284B; CN105044284A

Abstract

Provided is an experimental device for studying the porous medium skeleton change in a natural gas hydrate decomposition process, comprising an autoclave (1) capable of fast sampling, an inlet control unit, an outlet control unit, an environment temperature control unit, a gas-solid-liquid three-phase separation unit and a data processing unit. The autoclave (1) can be started quickly, and a porous medium skeleton can be taken out completely, so that the porous medium skeleton change caused by hydrate decomposition can be observed visually. Being simple to operate and easy to control, the experimental device and method are applicable to autoclaves (1) of various sizes and shapes.

Description

Experimental device and experimental method for studying the change of porous medium skeleton in natural gas hydrate decomposition process

Technical field

The invention relates to the field of multiphase seepage and natural gas hydrate exploitation in a porous medium, and particularly relates to an experimental device and an experimental method for studying a change of a skeleton of a porous medium during decomposition of a natural gas hydrate.

Background technique

Natural gas hydrate (NGH) is a kind of cage-shaped crystalline compound produced by natural gas and water under low temperature and high pressure. Its shape is like ice and snow, and it is burned in case of fire. It is commonly called "combustible ice". Natural gas hydrates in natural gas hydrates are mainly methane (>90%). At normal temperature and pressure, 1 m3 of natural gas hydrate decomposes and releases about 160 m ^{3 of} natural gas, so natural gas hydrates have extremely high energy density. Natural gas hydrates in nature are mainly found in sedimentary layers of the continental shelf and terrestrial tundra. In 1964, scientists first discovered natural gas hydrates in the Siberian tundra. Soon after, natural gas hydrates found in seabed sediments were discovered in the Black Sea. In the 1990s, industry scholars agreed that global gas hydrates store more energy than all oil, coal, and natural gas stored. In the past 20 years, the global deep-sea drilling program (DSDP), the Ocean Drilling Program (ODP) and the Integrated Ocean Drilling Program (IODP) have been conducted to investigate the mineral resources of natural gas hydrates. At present, the global total hydrate is estimated to be about 1015~1018 standard cubic meters. Therefore, natural gas hydrate (NGH) is considered to be the most potential alternative energy source for oil and gas in the 21st century. According to the resource survey, NGH is contained in the South China Sea, the East China Sea, the slopes, the Okinawa Sea, and the Qinghai-Tibet Plateau. Therefore, it is an effective way to alleviate the increasing energy pressure by studying the effective, rapid and economical exploitation method of natural gas hydrate and providing experimental basis and basis for large-scale exploitation of natural gas hydrate.

Therefore, natural gas hydrate mining technology is one of the key links to realize the development and utilization of natural gas hydrate resources. Unlike conventional fossil fuels, natural gas hydrates exist in a solid form in a porous medium. The basic idea of mining is to change the natural gas hydrate stable temperature-pressure environment, that is, the hydrate phase equilibrium conditions, causing the solid hydrate to be decomposed into natural gas and water in situ after the reservoir is produced. Accordingly, scientists have proposed several conventional mining techniques, such as: the pressure reduction method, the heat shock method, and the chemical reagent method. Due to the complex geological environment of hydrate deposits, the occurrence forms are diverse, and the mining process involves the phase transition process and multi-phase seepage process of multi-phase system composed of complex natural gas-water-sediment-hydrate-ice, hydrate production process. The change of the porous medium skeleton accompanying the decomposition of hydrate is one of the biggest problems encountered in the current hydrate mining. As the natural gas hydrates in the solid state become flowing water and gas, the geological characteristics of the original hydrate deposits will change greatly, such as permeability, porosity, mechanical properties and pore pressure. As a result, the porous medium skeleton is deformed, causing a three-phase mixed flow field of gas-solid liquid, which may eventually cause deformation of the formation. Therefore, studying the change of porous media skeleton during the decomposition of natural gas hydrate plays an important role in whether the hydrate mining technology can be successfully completed and the safety of hydrate mining technology.

At present, the world's more advanced hydrate mining research, the main research focuses on the effect of different mining methods on the hydrate phase transformation decomposition, and the heat consumption transfer in the hydrate decomposition process. However, under the real conditions, the understanding of the complex phase change seepage mechanism of the hydrate decomposition process is still in a fuzzy state. At present, almost all of the main hydrate mining simulation experiments neglect the influence of hydrate decomposition on the cytoskeletal change of hydrate reservoirs. In the previous simulation experiments, large particles were used to make porous media (particle size >100um), so that the hydrate decomposition process The porous medium skeleton cannot be changed. However, the particle size of the porous medium in the actual hydrate deposit is composed of 0.01 um microparticles to 500 um large particles, and the deformation of the porous medium skeleton is unavoidable during hydrate mining. One of the difficulties in the current hydrate mining technology is the lack of understanding of the gas-solid-liquid three-phase percolation mechanism of the porous medium-containing skeleton. It is necessary to obtain experimental data, and the phase change seepage in the hydrate decomposition process is directed to the hydrate sediment skeleton. The impact lacks basic experimental data, which is a key issue in the safety assessment of hydrate mining and requires experimental research.

Summary of the invention

The technical problem to be solved by the present invention is to provide an experimental apparatus and an experimental method which can visually observe the morphological change of the porous medium skeleton with the hydrate decomposition.

The technical solution of the present invention is:

An experimental device for studying changes in the skeleton of a porous medium during decomposition of natural gas hydrates, comprising a rapid sampling high pressure reactor, an inlet control unit, an outlet control unit, an ambient temperature control unit, a gas-solid liquid three-phase separation unit, and a data processing unit;

The rapid sampling high pressure reaction kettle is placed in an ambient temperature control unit, and a porous medium can be filled in a rapid sampling high pressure reactor to simulate a geological environment;

The inlet control unit is used to inject water and natural gas into the rapidly sampleable high pressure reactor;

The export control unit is used to control the rapid sampling high pressure reaction during the gas hydrate decomposition experiment. The outlet pressure of the kettle;

The ambient temperature control unit is used to control the gas hydrate formation/decomposition process and the temperature of the sampling process;

The gas-solid liquid three-phase separation unit is used for separating the gas-solid liquid mixture discharged after the decomposition of the weather hot water compound, and real-time metering the data of the gas-solid liquid three-phase output;

The high-speed reaction kettle, the ambient temperature control unit, the gas-solid liquid three-phase separation unit, the outlet control unit, and the induction component in the inlet control unit can be connected to the data processing unit through a signal line; the data processing unit is used for collecting and processing The sensing signal of each sensing element.

The rapid sampling high-pressure reactor of the experimental device can visually observe the morphological change of the porous medium skeleton with the hydrate decomposition, and meter the gas, solid and liquid three-phase production of the outlet. It is used to study the multi-phase seepage problem with solid phase migration in the process of decomposition and gas production of hydrate under different formation conditions under different formation conditions.

The quick sampling high pressure reaction kettle comprises a kettle lid, a kettle body and a quick opening mechanism for quick sampling, the quick opening mechanism comprises a clamp for fixedly connecting the kettle lid and the kettle body, and the kettle lid and the kettle body Sealed rubber ring. The quick opening mechanism is set so that the lid and the kettle body are quickly closed/opened, and the clamp is fixed, and the rubber ring seal makes it possible to quickly sample the high pressure reaction vessel, including the top pressure of the kettle lid to 25 MPa.

The quick-sampling high-pressure reactor has a cylindrical or rectangular parallelepiped inside, and a thin inner sleeve is disposed on the inner wall thereof. After the lid is quickly opened, the thin inner sleeve can be arranged to take out the porous medium sample conveniently and quickly. The high-speed reactor can be quickly sampled and the opening time is shorter than 30s. At present, the high pressure reactors related to hydrate mining research basically use bolts to fix the lid and the kettle body, and the opening time is often more than one hour. Due to the long opening time of the lid and the kettle body in the prior art, the porous medium skeleton has been When the morphological changes occur under the change of external conditions, the morphological change conditions of the observed porous medium skeleton with the decomposition of natural gas hydrate are lost.

The gas-solid liquid three-phase separation unit includes a screen sand remover and a gas-liquid separator connected in series with the screen sand remover.

The internal volume of the rapidly sampled high pressure reactor is greater than 0.5L. The high pressure reactor is made to reflect the multiphase seepage flow conditions in the real hydrate reservoir mining.

The porous medium has a particle size of less than 100 um. In the previous simulation experiments, large particles were used to form a porous medium (particle size > 100 um), so that the porous medium skeleton during the decomposition of the hydrate could not be changed. The porous medium of the present invention has a particle diameter of less than 100 um, and is intuitively observed to change the skeleton of the porous medium due to decomposition of the hydrate. Chemical.

Simulated injection wells and production wells are arranged in the fast sampling high pressure reactor according to requirements. A more realistic geological simulation environment can be obtained.

The outlet control unit is connected to the gas-solid liquid three-phase separation unit by a straight pipe or a large arc angle pipe. It can make the gas-solid liquid three-phase mixture output smoothly, effectively avoiding the blockage of the mixture in the pipeline.

An experimental method using the above experimental apparatus for studying the change of the skeleton of a porous medium in the decomposition process of natural gas hydrate, comprising the following steps:

S1: placing the rapidly sampled high pressure reaction kettle in the ambient temperature control unit, filling a porous medium in a rapidly sampled high pressure reaction vessel to simulate a geological environment; and setting an experimental ambient temperature through the inlet control The unit injects water and natural gas into the rapidly sampled high pressure reactor to generate a gas hydrate sample;

S2: after the gas hydrate formation is completed, the outlet pressure is controlled by the outlet control unit and the ambient temperature control unit controls the decomposition temperature to simulate a decomposition experiment of the generated sample in S1;

S3: After the experiment is completed or during the experiment, the morphology of the porous medium skeleton may be directly observed or decomposed by the gas hydrate decomposition.

When the gas-solid liquid three-phase separation unit separates the gas-solid mixture, the screen de-sander is used in series with the gas-liquid separator, and the solid-state separation is first performed, and the weight change of the weighing screen de-slicer is recorded to record the solid output, and then the solid output is recorded. The gas and liquid were separated and metered with a balance and a gas flow meter, respectively. The gas-solid liquid three-phase output data can be obtained accurately in real time, and the structure is simple.

When it is necessary to study the change of the porous medium skeleton at a certain moment, firstly, the outlet control unit is closed, and the overall temperature of the rapidly sampled high-pressure reaction reactor is lowered to -20 ° C to -40 ° C by the ambient temperature control unit, and the temperature is lowered. After fully releasing the outlet control unit, the pressure in the rapidly sampled high pressure reactor is reduced to one atmosphere, the lid is opened within 30 seconds, the porous medium skeleton is taken out, and the porous medium skeleton is directly observed or instrumentally measured with natural gas hydration. Morphological changes in the decomposition of matter. At this time, the remaining water in the reaction vessel becomes an ice state, and the hydrate hardly decomposes due to the "self-protection effect" under low temperature conditions. At this time, the reaction vessel was opened in 30 seconds by the quick opening mechanism in the reaction vessel. The porous medium skeleton was completely taken out, and the influence of hydrate decomposition on the morphological changes of the porous medium skeleton was studied by direct observation or instrumental measurement.

The beneficial effects of the invention:

The reactor can be quickly opened, and the porous medium skeleton can be completely taken out, so that the change of the porous medium skeleton due to the decomposition of the hydrate can be visually observed; the multiphase seepage problem containing the solid phase migration in the decomposition process of the natural gas hydrate can be studied; Accurately obtain the real-time output of gas-solid liquid three-phase in the decomposition process of natural gas hydrate; easy to operate, easy to control, suitable for reactors of various sizes and shapes; provide basic experimental data and theory for hydrate mining technology in accordance with.

DRAWINGS

1 is a block diagram of an experimental apparatus for changing a skeleton of a porous medium during decomposition of a natural gas hydrate according to the present invention;

2 is a schematic view of an experimental apparatus for studying changes in the skeleton of a porous medium during decomposition of natural gas hydrate according to an embodiment of the present invention.

detailed description

Example:

Referring to Figure 1, an experimental apparatus for studying the change of the skeleton of a porous medium in the decomposition process of natural gas hydrates includes: a rapid sampling high pressure reactor, an ambient temperature control unit, a gas-solid liquid three-phase separation unit, an outlet control unit, and an inlet control unit. And a data processing unit. The rapid sampling high pressure reactor is placed in an ambient temperature control unit for controlling the hydrate formation/decomposition process and the temperature of the sampling process. The high-speed reaction kettle can be quickly sampled to achieve quick opening by setting a quick-opening kettle lid. Preferably, the lid and the kettle body are fixedly connected by a clamp, and the rubber ring is used for sealing; in the rapid sampling high-pressure reaction kettle, the simulated injection well is arranged according to requirements. Mining wells. The inlet control unit, the rapid sampling high pressure reaction kettle, the outlet control unit, and the gas-solid liquid three-phase separation unit are sequentially connected through the control valve and the pipeline. The rapid sampling high-pressure reaction kettle, the ambient temperature control unit, the gas-solid liquid three-phase separation unit, the outlet control unit, and the inlet control unit are all provided with sensing elements, and each sensing element is connected to the data processing unit through a signal line.

Further, the rapid sampling high pressure reactor is filled with porous medium, water and natural gas are injected from the inlet control unit, and the hydrate formation temperature is controlled by the ambient temperature control unit to generate a hydrate sample. Decomposition experiments and porous media skeleton deformation studies can be started when the hydrate sample is formed. At the beginning of the hydrate decomposition experiment, the outlet pressure is controlled by the outlet control unit, and with the decomposition of the hydrate, the gas-solid mixture in the high-pressure reactor can be quickly sampled and released to the outside of the rapidly sampled high-pressure reactor, and the gas-solid mixture is discharged. The compound is separated by a gas-solid liquid three-phase separation unit and metered in real time and recorded by a data processing unit. In the process of decomposition of the whole hydrate, when it is necessary to study the change of the skeleton of the porous medium at any moment, the outlet control unit is first closed, and the overall temperature of the rapidly sampled high-pressure reactor is rapidly lowered to -20 ° C by the ambient temperature control unit. At 40 ° C, after the temperature is lowered, the outlet control unit is completely released, so that the pressure in the high-speed reaction vessel can be rapidly reduced to atmospheric pressure. At this time, the remaining water in the high-pressure reaction vessel can be quickly sampled to become an ice state, and the hydrate hardly decomposes due to the "self-protection effect" under low temperature conditions. At this time, the rapid sampling high pressure reactor is opened by a quick opening mechanism in the rapid sampling high pressure reactor. Using a thin inner sleeve that can be quickly sampled in a high-pressure reactor, the porous medium skeleton is completely taken out within 30 s, and the influence of hydrate decomposition on the morphology change of the porous medium skeleton is studied by direct observation or instrumental measurement.

Further, the lid of the high-pressure reaction vessel that can be quickly sampled is closed/opened by a quick opening mechanism, and the maximum design pressure can reach 25 MPa. In order to facilitate the removal of the porous medium sample, the inside of the reaction vessel can be designed as a cylindrical or rectangular parallelepiped. A thin inner sleeve is arranged on the inner wall of the reaction vessel, and after the quick opening of the kettle lid is opened, the entire porous medium block can be completely taken out without breaking the porous medium skeleton. The internal volume of the high-pressure reactor can be quickly sampled to be greater than 0.5L, and the volume is too small to reflect the multi-phase flow conditions in the real hydrate reservoir mining. Quickly sample high-pressure reactors. Physical sensors such as temperature measurement and pressure measurement can be designed as needed to study physical and chemical changes in porous media during hydrate decomposition. It is also possible to increase the confining pressure or axial compression system to obtain a more realistic geological simulation environment.

Further, the outlet control unit includes an outlet pressure control mechanism and a well cluster extending into the simulated cavity of the rapidly sampleable high pressure reactor. The equipment technical requirements that the export control unit needs to meet include well settings that conform to different hydrate production methods, and the outlet control unit can accurately control the outlet pressure, so that the gas-solid liquid three-phase mixture can be smoothly produced, and the gas-solid liquid mixture can be effectively avoided. Blockage inside the pipe. In order to achieve this technical goal, a straight pipe connection can be used in the outlet control unit to avoid bending and valves as much as possible. When it is unavoidable, use a large curved angle tube and a high pressure ball valve or other valve that can make the solid phase pass smoothly to avoid pipe blockage.

Further, the ambient temperature control unit needs to control the ambient temperature at which the hydrate is formed and decomposed, and can rapidly reduce the temperature of the high-pressure reactor to be quickly sampled to between minus 20 and 40 degrees. Therefore, the ambient temperature control unit is preferably designed to control the temperature using a common water bath during hydrate formation or decomposition, with a temperature range of 0-30 ° C and a high precision of 0.1 ° C. In the case of rapid cooling, the water in the water bath is evacuated, and liquid nitrogen or other coolant is injected to rapidly cool down. Stop adding liquid nitrogen when the temperature reaches minus 20 degrees, when the temperature When the degree is higher than minus 20 degrees, the liquid nitrogen is kept at a low temperature.

Further, the gas-solid liquid three-phase separation unit can realize separation and real-time metering of the produced gas-solid liquid three-phase. In order to achieve this technical effect, a screen desander can be used in series with the gas-liquid separator. The solid state is separated first, and the weight change of the weighing screen de-sander is recorded to record the solid output, and then the gas-liquid is separated and used separately. The balance is metered with a gas flow meter. The advantage of using this combination is that the gas-solid liquid three-phase output data can be obtained accurately in real time, and the structure is simple.

Referring to FIG. 2, the high-speed reaction vessel 1 can be quickly sampled, including a kettle lid, a kettle body and a quick opening mechanism; the quick opening mechanism includes a clamp for fixing the lid of the kettle lid and the kettle body, and sealing the kettle lid and the kettle body Rubber ring. The high pressure reactor 1 can be quickly sampled and placed in an ambient temperature control unit (cold tank 10) for controlling the hydrate formation/decomposition process and the temperature of the sampling process. The simulated injection well and the production well can be arranged in the high-speed reactor 1 and the porous medium can be filled in the rapid sampling high-pressure reactor to simulate the geological environment. The porous medium has a particle size of less than 100 μm.

The inlet control unit consists of a liquid injection system 11, a gas injection system 12 and an evacuation system 13. The liquid injection system 11 is composed of a double plunger pump 111, a preheater 112, and a pressure sensor 113. The double plunger pump 111 controls the water injection flow rate, the preheater 112 controls the water injection temperature, and the pressure sensor 113 monitors the inlet pressure. The gas injection system 12 is composed of a gas cylinder 121, a pressure regulating valve 122, an air compressor 123, a gas boosting pump 124 and a flow meter 125. The gas cylinder 121 provides a gas source, and the pressure regulating valve 122 sets the gas source pressure and air pressure. The machine 123 and the gas booster pump 124 inject gas into the reactor for gas pressurization, while the flow meter 125 meters the injected gas flow. The evacuation system 13 is composed of a vacuum gauge 131, a buffer tank 132, and a vacuum pump 133, and the exhaust gas in the reaction vessel can be discharged to form a vacuum.

The outlet control unit includes an outlet pressure control mechanism 100 and a well cluster 101 that extends into the simulated cavity of the rapidly sampleable high pressure reactor.

The gas-solid liquid three-phase separation unit is composed of a screen sand remover 21, a back pressure valve 22, a gas-liquid separator 23, a gas flow meter 24, a liquid collection cylinder 25, and an electronic scale 26, and an outlet control unit outlet is connected to the screen to remove sand. The device 21 realizes solid phase separation. The screen remover 21 is connected to a back pressure valve 22 composed of a buffer container 221, a pointer pressure gauge 222, and a hand pump 223, and the back pressure valve 22 controls the outlet pressure. The back pressure valve 22 is connected to the gas-liquid separator 23 to achieve gas-liquid separation. The exhaust gas is metered by the gas flow meter 24, and the liquid is collected by the liquid collection cylinder 25, and then the electronic scale 26 is metered.

Taking the internal volume of the fast-sampling high-pressure reactor as 1L as an example; in the fast-sampling high-pressure reactor, a total of 27 temperature measurement points and two pressure measurement points are used to study the hydrate decomposition process. The physico-chemical changes in the porous medium, the wellhead designed on the high-pressure reactor with five-point method can meet the experiments of various hydrate mining methods such as depressurization method, heat injection method and injection inhibitor method.

The experiment needs to study the change of the porous medium skeleton at 30 minutes after the start of hydrate decomposition. When the depressurization test is carried out until the 30th minute, the outlet control unit is first closed, the cooling water in the water bath is taken out, and the overall temperature of the rapidly sampling high-pressure reactor is rapidly lowered to -20 ° C to -40 by injecting liquid nitrogen. °C, after the temperature is lowered, the back pressure valve is completely released, so that the pressure in the high-pressure reaction vessel can be rapidly reduced to atmospheric pressure. At this time, the remaining water in the high-pressure reaction vessel can be quickly sampled to become an ice state, and the hydrate hardly decomposes due to the "self-protection effect" under low temperature conditions. At this point the lid is opened by a rapid sampling mechanism that can be quickly sampled in a high pressure reactor. The porous medium skeleton was completely taken out, and the influence of hydrate decomposition on the morphological changes of the porous medium skeleton was studied by direct observation or instrumental measurement.

In summary, the experimental device for studying the change of the porous medium skeleton in the decomposition process of natural gas hydrate provided by the present invention can study the multiphase seepage problem containing solid phase migration in the decomposition process of natural gas hydrate; and can accurately obtain natural gas hydrate The real-time output of gas-solid liquid three-phase in the decomposition process; the change of porous medium skeleton caused by hydrate decomposition can be visually observed; the operation is simple and easy to control, and it is suitable for reactors of various sizes and shapes; The mining technology provides basic experimental data and theoretical basis.

The detailed description above is a detailed description of the possible embodiments of the present invention, which is not intended to limit the scope of the invention, and the equivalents and modifications of the present invention should be included in the scope of the patent. in.

Claims

An experimental device for studying the change of the skeleton of a porous medium in the decomposition process of natural gas hydrate, characterized in that it comprises a rapid sampling high pressure reaction kettle, an inlet control unit, an outlet control unit, an ambient temperature control unit, a gas-solid liquid three-phase separation unit, and Data processing unit;

The rapid sampling high pressure reaction kettle is placed in an ambient temperature control unit, and a porous medium can be filled in a rapid sampling high pressure reactor to simulate a geological environment;

The inlet control unit is used to inject water and natural gas into the rapidly sampleable high pressure reactor;

The outlet control unit is used to control the outlet pressure of the high-pressure reaction vessel during the natural gas hydrate decomposition experiment to smoothly produce the gas-solid liquid three-phase mixture;

The ambient temperature control unit is used to control the gas hydrate formation/decomposition process and the temperature of the sampling process;

The gas-solid liquid three-phase separation unit is used for separating the gas-solid liquid mixture discharged after the decomposition of the weather hot water compound, and real-time metering the data of the gas-solid liquid three-phase output;

The high-speed reaction kettle, the ambient temperature control unit, the gas-solid liquid three-phase separation unit, the outlet control unit, and the induction component in the inlet control unit can be connected to the data processing unit through a signal line; the data processing unit is used for collecting and processing The sensing signal of each sensing element.
The experimental apparatus for studying the change of the skeleton of the porous medium in the decomposition process of the natural gas hydrate according to claim 1, wherein the rapidly sampling high-pressure reaction kettle comprises a kettle lid, a kettle body and a quick opening mechanism; and the quick opening mechanism comprises A clamp for fixedly connecting the lid and the kettle body, and a rubber ring for sealing the lid and the kettle body.
The experimental device for studying the change of the skeleton of the porous medium in the decomposition process of the natural gas hydrate according to claim 1 or 2, wherein the rapid sampling high-pressure reaction vessel has a cylindrical or rectangular parallelepiped inside, and a thin layer is arranged on the inner wall thereof. Inner sleeve.
The experimental apparatus for studying the change of the skeleton of a porous medium in the decomposition process of natural gas hydrate according to claim 1, wherein the gas-solid liquid three-phase separation unit comprises a screen desander and is connected in series with the screen desander. Gas-liquid separator.
The experimental apparatus for studying the change of the skeleton of the porous medium in the decomposition process of the natural gas hydrate according to claim 1, wherein the internal volume of the rapidly sampled high pressure reactor is greater than 0.5L.
The experimental apparatus for studying the change of the skeleton of a porous medium in the decomposition process of natural gas hydrate according to claim 1, wherein the porous medium has a particle diameter of less than 100 μm.
The experimental device for studying the change of the skeleton of the porous medium in the decomposition process of natural gas hydrate according to claim 1, wherein the outlet control unit adopts a straight pipe or a large arc angle pipe and the gas-solid liquid three-phase separation unit. Connected.
An experimental method using the experimental device for studying the change of the skeleton of a porous medium in the decomposition process of natural gas hydrate according to claim 1, characterized in that it comprises the following steps:

S1: placing the rapid sampling high pressure reaction kettle in the ambient temperature control unit, filling a porous medium in a rapid sampling high pressure reaction kettle to simulate a geological environment, and setting an experimental environment temperature, and controlling through the inlet The unit injects water and natural gas into the rapidly sampled high pressure reactor to generate a gas hydrate sample;

S2: after the gas hydrate formation is completed, the outlet pressure is controlled by the outlet control unit and the ambient temperature control unit controls the decomposition temperature to simulate a decomposition experiment of the sample generated in S1;

S3: After the experiment is completed or during the experiment, the morphology of the porous medium skeleton may be directly observed or decomposed by the gas hydrate decomposition.
The experimental method for studying an experimental device for changing a skeleton of a porous medium in a gas hydrate decomposition process according to claim 8, wherein the gas-solid liquid three-phase separation unit uses a sieve de-slurry device for separating the gas-solid mixture It is used in series with the gas-liquid separator. The solid state is separated first, and the weight change of the weigher of the screen is recorded to record the solid output, and then the gas and liquid are separated, and respectively measured by a balance and a gas flow meter.
The experimental method for studying an experimental apparatus for changing a skeleton of a porous medium during decomposition of a natural gas hydrate according to claim 8, wherein when the change of the skeleton of the porous medium at any time is required to be studied, the outlet control unit is first closed. The overall temperature of the rapidly sampleable high pressure reactor is lowered to -20 ° C to -40 ° C by the ambient temperature control unit, and the outlet control unit is completely released after the temperature is lowered, so that the pressure in the high-speed reaction kettle can be quickly sampled. The pressure is reduced to one atmosphere, the lid is opened within 30 seconds, the porous medium skeleton is taken out, and the morphology of the porous medium skeleton is decomposed with the decomposition of the natural gas hydrate by direct observation or instrument.