CN109557252B

CN109557252B - Comprehensive hydrate simulation system

Info

Publication number: CN109557252B
Application number: CN201811301890.4A
Authority: CN
Inventors: 陆程; 孙晓晓; 王静丽; 耿澜涛; 李占钊; 马超; 王偲; 张渴为
Original assignee: Guangzhou Marine Geological Survey
Current assignee: Guangzhou Marine Geological Survey
Priority date: 2018-11-02
Filing date: 2018-11-02
Publication date: 2021-02-02
Anticipated expiration: 2038-11-02
Also published as: CN109557252A

Abstract

The invention discloses a comprehensive hydrate simulation system, which generally comprises a negative pressure sample cavity for placing a sample, a ring pressure system connected with the negative pressure sample cavity, a parameter measurement system, a constant temperature system, a vacuum system, a gas injection system, a liquid injection system, a heat injection system, a drilling fluid circulating system, a back pressure system and a data acquisition and processing unit. The simulation system can simulate the development of the natural gas hydrate in all directions, can be used for indoor research on the mechanism of synthesizing and decomposing the natural gas hydrate in the sea area of China, and provides a support in the aspect of physical simulation for mastering important sensitive parameters influencing the trial production, such as reservoir physical properties, temperature, pressure, yield change rules and the like under different development modes and different development well groups in the trial production process of the sea area hydrate.

Description

Comprehensive hydrate simulation system

Technical Field

The invention relates to the field of geology, in particular to a comprehensive simulation system and an experiment method thereof, which can realize multiple experiments such as hydrate single-phase and two-phase permeability measurement, hydrate gas injection exploitation simulation, hydrate formation and decomposition simulation, hydrate reservoir drilling pollution simulation and the like.

Background

Since this century, natural gas hydrate has been recognized worldwide as a clean energy source to replace conventional fossil fuels. The world has found hydrate deposit points over 200, and only 15% of hydrates can be exploited for the global use for 200 years according to the current energy consumption trend. However, the stable temperature and pressure conditions formed by the mining method determine the particularity of the mining method, and the influence on the environment during the mining process is still to be further evaluated. Therefore, most of the current research on hydrate mining is in the phase of laboratory physical and numerical simulation, except that few countries and regions have already performed pilot mining of a single well or a single well group.

At present, in order to develop and utilize the energy with huge reserves, researchers propose a plurality of methods:

firstly, a heat injection method: heating the hydrate above the equilibrium temperature with injection of hot water, steam or hot brine to decompose;

a depressurization method: reducing the pressure of the hydrate reservoir to below the equilibrium decomposition pressure;

③ chemical agent method: a chemical agent, such as methanol or ethylene glycol, is injected to change the hydrate equilibrium generating conditions.

The existing research equipment can only be developed on one aspect, can not comprehensively analyze the variation factors of the corresponding environment of the hydrate in the generation or decomposition process, and is not beneficial to the application in actual exploitation.

Disclosure of Invention

The invention provides a comprehensive simulation system capable of realizing multiple experiments of hydrate single-phase and two-phase permeability measurement, hydrate gas injection exploitation simulation, hydrate formation and decomposition simulation, hydrate reservoir drilling pollution simulation and the like.

In particular, the present invention provides a comprehensive hydrate simulation system comprising:

the negative pressure sample cavity is a hollow pipe body which is horizontally arranged, the inner wall of the negative pressure sample cavity is roughened by adopting pulse to fill the muddy silt porous medium of the seabed hydrate reservoir, one end of the negative pressure sample cavity is sealed by a sealing structure with a communicating pipeline, the other end of the negative pressure sample cavity is connected with a shaft pressure loading piston which applies axial pressure to the porous medium, the pipe body is provided with mounting holes and sapphire visual windows at intervals along the axial direction, and the circumference where the mounting holes are located is uniformly provided with a plurality of mounting holes;

the annular pressure system applies pressure to the porous medium in the negative pressure sample cavity by the antifreeze to simulate the formation pressure state;

the parameter measuring system is arranged in each mounting hole of the negative pressure sample cavity to simultaneously measure data of the porous medium in different simulation processes, and each mounting hole is respectively provided with a bag-type pressure gauge for measuring pressure, a temperature sensor for measuring temperature and an electrode for measuring resistance through a fixed seat; the negative pressure sample cavity is internally provided with a negative pressure sample cavity, the negative pressure sample cavity is provided with a mounting hole, the mounting hole is internally provided with a central channel, the negative pressure sample cavity is internally provided with a limiting sheet and an anti-falling sleeve, the limiting sheet is a flexible wafer and is provided with a plurality of axial through jacks, the limiting sheet is horizontally arranged in the central channel, the anti-falling sleeve is screwed on the external opening end of the central channel through external threads, and the front end of the anti-falling sleeve props against the limiting sheet; the bag-type pressure measuring device, the temperature sensor and the measuring electrode penetrate through jacks on the anti-release sleeve and the limiting sheet and then extend into the negative pressure sample cavity, a sealing element is arranged on the outer circumference of one end, in contact with the fixed seat, of the anti-release sleeve, an anti-rotation bolt for preventing a signal line from loosening is arranged at the other end of the anti-release sleeve, a through hole is formed in the radial direction of the anti-rotation bolt, a corresponding limiting hole is formed in the anti-release sleeve, and after the anti-rotation bolt is rotated in place, the anti-rotation bolt is screwed into the through hole and the limiting hole;

the constant temperature system is used for keeping the environmental temperature of the negative pressure sample cavity during the experiment through a constant temperature box sleeved outside the negative pressure sample cavity;

the vacuum system is used for vacuumizing the negative pressure sample cavity through a vacuum pump so as to provide a clean experimental environment;

the gas injection system injects gas into the negative pressure sample cavity through the gas compressor to synthesize cooled hydrate or measure the gas permeability of the hydrate reservoir in different exploitation states;

the liquid injection system injects specified cooling liquid into the negative pressure sample cavity through the constant-speed constant-pressure pump and is used for synthesizing a hydrate by the current porous medium or analyzing the liquid permeability of the current porous medium;

the heat injection system is used for injecting heat mass into the negative pressure sample cavity to simulate the process of heat injection exploitation of hydrate in the porous medium, so that the decomposition and migration states of the hydrate can be conveniently analyzed;

the drilling fluid circulating system outputs the drilling fluid through the liquid storage device to realize annular circulation flow at the cavity opening of the negative pressure sample cavity, and is used for simulating and analyzing the influence and pollution of the drilling fluid on the conductivity characteristics of a hydrate reservoir;

the back pressure system is used for controlling the gas pressure in the negative pressure sample cavity, carrying out gas-liquid separation on the fluid generated by the decomposition of the hydrate and measuring the gas and water yield;

the data acquisition and processing unit comprises a control system with data processing software, and realizes data acquisition, analysis and result output for different experimental processes while controlling the experimental processes.

In one embodiment of the invention, the gas injection system comprises an air compressor for generating pressure gas, a gas booster pump for boosting the gas generated by the air compressor, a low-pressure storage tank for storing the boosted low-pressure gas, a high-pressure storage tank for storing the boosted high-pressure gas, a pressure regulating valve for inputting specified pressure into the negative-pressure sample cavity by selecting the low-pressure storage tank or the high-pressure storage tank according to experimental requirements, a flow controller for controlling the flow of the output gas, and a cooler for cooling the injected gas and liquid; and a gas wetting device is arranged on a gas path before the pressure reducing valve, and is a pressure-resistant container filled with liquid.

In one embodiment of the invention, the constant-speed constant-pressure pump of the liquid injection system is a double-cylinder constant-speed constant-pressure pump, the double-cylinder constant-speed constant-pressure pump realizes single-cylinder independent operation, double-cylinder independent operation and double-cylinder linkage operation through two cylinders, distilled water or kerosene is used as a driving medium to be output, and the constant-pressure, constant-flow and tracking PLC control of the driving medium is realized in the output process;

the liquid injection system also comprises a pressure adjusting piston arranged between the double-cylinder constant-speed constant-pressure pump and the negative pressure sample cavity, the pressure adjusting piston comprises a hollow container with two open ends, an upper cover and a lower cover are respectively screwed at the two ends of the hollow container through external threads, sealing plugs are respectively arranged inside the two ports of the hollow container, a connecting platform protruding outwards is arranged on one surface of the sealing plug, which is far away from the hollow container, through holes for the connecting platform to pass through are arranged on the upper cover and the lower cover, and an axial through hole is arranged on the connecting platform;

a partition board which can move along the axial direction and separates the interior of the hollow container into two independent cavities is arranged in the hollow container; one cavity is communicated with the double-cylinder constant-speed constant-pressure pump, the other cavity is communicated with the negative pressure sample cavity, a solution which is generated by a hydrate is filled in the cavity communicated with the negative pressure sample cavity, and the solution is pushed by distilled water or kerosene in the other cavity and is injected into the negative pressure sample cavity.

In one embodiment of the present invention, the heat injection system includes a steam generator for simultaneously providing steam and hot water, the steam generator includes a heating tube having a heating chamber therein, a tube wall of the heating tube has a double-layer hollow structure, a hot water space is provided in the middle of the tube wall, a heating tube having an annular or polygonal shape and directly communicating with the hot water space in the tube wall is provided in the heating chamber, a heater is provided below the heating tube, a steam tube for discharging the steam generated in the heating tube is provided above the heating tube, and a cold water exchange region for adjusting an output temperature is provided on an output channel of the steam tube;

the system also comprises temperature probes for detecting the temperature of each part, pressure probes for detecting input and output pressure, a water inlet pipe for supplying water to the hot water space and the cold water exchange area, a water outlet pipe for outputting steam and/or hot water, and a PLC control unit for controlling the output of preset steam or hot water according to instructions, wherein the exchange area is communicated with the hot water space through a pipeline with a control valve.

In one embodiment of the invention, the inside of the incubator is a heat preservation space for accommodating the negative pressure sample cavity, two opposite sides in the incubator are provided with blowers for refrigerating and realizing hot air convection in the incubator body, and an adjusting air port connected with a refrigerating system, the inner surface of the incubator is provided with a heat preservation layer, the incubator body is provided with a transparent observation window and a temperature control panel, and the incubator body is internally provided with bearing seats for supporting two ends of the negative pressure sample cavity.

In one embodiment of the invention, the constant temperature box is connected with a heating system through a pipeline so as to realize mutual waste heat utilization.

In one embodiment of the invention, the liquid storage device comprises a liquid storage tank for storing well liquid, a circulating pump for controlling the circulation flow of the well liquid, a temperature controller for heating the circulating well liquid, a pressure regulating device for regulating the pressure of the well liquid during circulation, and a simulated wellhead annular structure arranged at the end part of the negative pressure sample cavity;

the outlet of liquid storage pot is connected the circulating pump after and is connected the entry linkage of simulation well head annular structure, the export of simulation well head annular structure with the pressure regulating device be connected the back with the input connection of liquid storage pot, the temperature controller is connected with the liquid storage pot alone, the output of circulating pump passes through branch pipe and liquid storage union coupling.

In one embodiment of the present invention, the restricting piece is provided in plurality, and the restricting pieces are provided at intervals or in contact with each other.

In one embodiment of the invention, the bag-type pressure gauge comprises a pressure measuring pipe, a pressure measuring pipe sleeved outside the pressure measuring pipe, a bag-type isolation sleeve positioned at the end part of the pressure measuring pipe and used for hermetically accommodating the end part of the pressure measuring pipe, and an injection device for injecting antifreeze into the pressure measuring pipe; the tip surface of the pressure pipe is provided with the radial bulge loop of multichannel, bag formula isolation sleeve is one end open-ended flexible cover, is provided with the concave ring that corresponds with the bulge loop at the internal surface of open end, bag formula isolation sleeve utilize the concave ring with link together after the bulge loop block on the pressure pipe, form the protection space who holds the antifreeze in inside.

In one embodiment of the invention, the mounting holes in the same radial direction of the negative pressure sample cavity are distributed on the circumference of the negative pressure sample cavity in a linear symmetry or triangular symmetry manner, the number of the mounting holes is 8-12, and at least 4 temperature sensors are arranged at one mounting hole and are respectively positioned at 1/4, 2/4, 3/4 and the axle center of the radial line of the negative pressure sample cavity.

In one embodiment of the invention, the sealing structure of the negative pressure sample cavity comprises a flange fixed at a pipe orifice at one end and a seal head movably sealing the opening end of the pipe orifice, wherein the flange is fixed at the pipe orifice through a pressure-bearing screw and limits the seal head at the opening end of the pipe orifice; the end socket is provided with a plurality of axial through holes for connecting a test pipeline, a sealing element is arranged at the position where the outer circumference of the end socket is contacted with the inner side wall of the pipe orifice, a filter for isolation is arranged between the end socket and the porous medium, meanwhile, a flow guide groove for dispersing liquid output by the axial through holes into surface output is arranged on the end surface of one end contacted with the porous medium, and the flow guide groove comprises annular grooves which are distributed on the end surface at intervals in an annular mode and radial grooves which are communicated with the axial through holes and the annular grooves.

In one embodiment of the invention, a loading cavity is installed at the other end of the negative pressure sample cavity, the axial pressure loading piston is inserted into the loading cavity, the outer circumference of the axial pressure loading piston is the same as the diameter of the inner circumference of the negative pressure sample cavity, a filter for preventing the porous medium from passing through is arranged between the end face of the axial pressure loading piston and the porous medium, and the loading cavity limits the axial pressure loading piston in the loading cavity through a sealing gland at the end opposite to the end connected with the negative pressure sample cavity.

In one embodiment of the invention, a steady-state measuring device for realizing steady-state hot wire measurement is arranged in the negative pressure sample cavity, and comprises a platinum hot wire inserted in the negative pressure sample cavity and positioned on an axial lead, a sheath sleeved outside the platinum hot wire, and fixed seats for fixing two ends of the sheath and the platinum hot wire on end sockets at two ends of the negative pressure sample cavity and an axial pressure loading piston;

the fixing seat is internally provided with an axial through hole which is connected with a mounting hole on the end socket or the axial compression loading piston through an external thread at one end, a sealing compression ring with extrusion deformation is mounted in the mounting hole, a tensioning joint is screwed on the external thread at the other end of the fixing seat, an adjusting nut for adjusting the tension degree of the tensioning joint is mounted at one end of the tensioning joint close to the fixing seat, an inverted wedge squeezing ring with a groove is mounted in the end head at the other end of the tensioning joint, and a tightening pressure cap for limiting the inverted wedge squeezing ring on the tensioning joint.

In one embodiment of the invention, the back pressure system comprises a back pressure valve connected to a pipeline for outputting the hydrate from the negative pressure sample cavity, a back pressure meter for displaying the pressure on the back pressure valve, a back pressure pump and a back pressure container for adjusting the pressure at the back pressure valve to automatically release when the output pressure of the negative pressure sample cavity exceeds the standard pressure, a gas-liquid separator for performing gas-liquid separation on the received hydrate, a gas tank for receiving and metering the separated gas, and a weighing device for weighing the separated liquid.

In one embodiment of the invention, the sapphire viewing windows are oppositely arranged on two sides of the negative pressure sample cavity.

In one embodiment of the invention, the negative pressure sample cavity bears a displacement pressure of more than or equal to 14-18 MPa and an annular pressure of more than or equal to 40-50 MPa during an experiment.

The simulation system can simulate the development of the natural gas hydrate in all directions, can be used for indoor research on the mechanism of synthesizing and decomposing the natural gas hydrate in the sea area of China, and provides a support in the aspect of physical simulation for mastering important sensitive parameters influencing the trial production, such as reservoir physical properties, temperature, pressure, yield change rules and the like under different development modes and different development well groups in the trial production process of the sea area hydrate.

The spatial distribution of a temperature field, the spatial distribution of a saturation field, the advancing speed of a hydrate decomposition front, the decomposition mechanism of the hydrate and the like in the synthesis and decomposition processes of the hydrate can be researched; optimizing development parameters by controlling and changing production data such as bottom pressure, heat injection temperature and the like of a production well; and optimizing a well pattern development scheme by comparing the dynamic characteristics of the mining of the hydrate under the conditions of different well pattern modes and well pattern densities.

The seepage performance of the hydrate-containing stratum can be tested, and the relation between the permeability and the saturation of the hydrate stratum and the influence of the decomposition of water and matters on the permeability of the stratum can be mastered. The method can simulate the influence of drilling fluid invasion on the conductivity of the hydrate formation under different conditions, and provides a basis for hydrate formation resistivity logging in the future. The method can also be used for researching water and gas migration in a hydrate stratum and the gas production rate of a hydrate reservoir under the conditions of pressure reduction and thermal recovery, can also be used for researching an indoor horizontal well water outlet mechanism and water control and water plugging process technology, observing a water ridge advancing process when a horizontal well is used for exploiting a bottom water reservoir, and researching a change rule of a water ridge forming and developing mechanism, water breakthrough time and recovery rate.

The seepage performance of the hydrate-containing stratum can be tested, and the relation between the permeability and the saturation of the hydrate stratum and the influence of the decomposition of water and matters on the permeability of the stratum can be mastered. The method can simulate the influence of drilling fluid invasion on the conductivity of the hydrate formation under different conditions, and provides a basis for hydrate formation resistivity logging in the future. The water and gas migration in the hydrate formation and the gas production of the hydrate reservoir under the conditions of decompression and thermal recovery can also be researched.

Drawings

FIG. 1 is a schematic diagram of a simulation system connection according to an embodiment of the present invention;

FIG. 2 is a schematic diagram of a negative pressure sample chamber configuration according to one embodiment of the present invention;

FIG. 3 is a schematic view of a gas injection apparatus connection according to an embodiment of the present invention;

FIG. 4 is a schematic view of a liquid injection device connection according to an embodiment of the present invention;

FIG. 5 is a schematic structural view of a pressure regulating piston according to an embodiment of the present invention;

FIG. 6 is a schematic view of a reservoir attachment according to one embodiment of the present invention;

FIG. 7 is a schematic diagram of a back pressure system connection according to an embodiment of the present invention;

FIG. 8 is a schematic diagram of a parameter measurement system according to an embodiment of the present invention;

FIG. 9 is a schematic diagram of a bladder pressure gauge according to an embodiment of the present invention;

FIG. 10 is a schematic view of a mounting hole for a negative pressure sample chamber according to an embodiment of the present invention;

FIG. 11 is a schematic view of a seal configuration according to an embodiment of the present invention;

FIG. 12 is a schematic view of the structure of the channels on the header in accordance with one embodiment of the present invention;

FIG. 13 is a schematic structural view of a shaft pressure loading piston in accordance with one embodiment of the present invention;

fig. 14 is a schematic structural view of a steady-state measuring device according to an embodiment of the present invention.

Detailed Description

In the following description, the inside of each system and the connection between the system and the rectangular cavity are connected through a pipeline with a control valve, and the specific connecting pipeline and the control valve are not shown in a specific mode except for specific description, but are only described in a working process or experimental steps.

As shown in fig. 1, one embodiment of the present invention provides a comprehensive hydrate simulation system, which generally includes a negative pressure sample chamber 1, an annular pressure system 2, a parameter measurement system 3, a constant temperature system 4, a vacuum system, a gas injection system 5, a liquid injection system 6, a heat injection system 7, a drilling fluid circulation system 8, a back pressure system 9 and a data acquisition and processing unit 10.

As shown in fig. 2, the negative pressure sample chamber 1 is used as a main body for simulating various experiments of samples, and is a hollow tube 101 horizontally arranged as a whole, the inside of the hollow tube 101 is used for filling a seabed hydrate reservoir muddy silt porous medium for testing, one end of the tube 101 is sealed by a sealing structure 105, a pipeline for connecting each external system is arranged on the sealing structure 104, the other end of the hollow tube is connected with an axial pressure loading piston 105 for applying axial pressure to the porous medium in the negative pressure sample chamber 1, mounting holes 102 are axially arranged at intervals on the circumference of the tube 101, and a plurality of mounting holes 102 are uniformly arranged on the circumference where each mounting hole 102 is arranged.

The negative pressure sample cavity 1 is integrally made of a steel pipe or a stainless steel pipe, the specific size can be phi 50 multiplied by 1200mm, the borne pressure is greater than the pressure of the actual stratum, the displacement pressure in the scheme is about 16MPa, and the ring pressure is about 25 MPa.

The ring pressure system 2 forms confining pressure by injecting pressure-applying anti-freezing solution into the negative pressure sample cavity 1 so as to simulate the pressure state of the stratum where the porous medium is located.

The parameter measuring system 3 is used for measuring various parameters of the porous medium in the simulation process of each system, the measurement purpose is realized by a plurality of measuring components 103 which are arranged in each mounting hole 102 of the negative pressure sample cavity 1 through a fixing seat 301, the collection and management of the measured data are controlled by a data acquisition and processing unit 10, and the measuring components 103 which are respectively arranged in each mounting hole 102 specifically comprise a bag-type pressure measuring device for measuring pressure, a temperature sensor for measuring temperature and an electrode for measuring resistance. As shown in fig. 8, a limiting plate 302 and an anti-drop sleeve 303 are disposed in the fixing base 301, the mounting hole 102 on the negative pressure sample chamber 1 is a circular through hole, a central channel is disposed in the fixing base 301, and the fixing base is hermetically fixed in the mounting hole 102 by welding or screwing.

The limiting pieces 302 are flexible or metal round pieces and are provided with a plurality of axial through insertion holes, the axial through insertion holes are used for enabling cables of all measuring assemblies to pass through, the axial through insertion holes are horizontally arranged in the central channel, one or more limiting pieces 302 can be used according to sealing requirements, the limiting pieces 302 can be mutually overlapped and arranged, the passing cables are elastically fixed, and meanwhile the measuring positions of the corresponding measuring assemblies are conveniently adjusted.

The anti-slip cover 303 is also a tubular structure with a central passage for passing the cable in the middle, and is screwed on the internal thread of the external opening end of the central passage of the fixed seat 301 through external threads, and the front end of the anti-slip cover 303 can press the limiting piece 302 through the screwing depth to prevent the limiting piece 302 from moving axially.

The bag-type pressure detector 306, the temperature sensor 307 and the measuring electrode 305 penetrate through holes on the anti-falling sleeve 303 and the limiting sheet 302 and then extend into the negative pressure sample cavity 1; in order to improve the pressure resistance of the joint, a sealing element 308 can be arranged on the outer circumference of one end of the anti-falling sleeve 303, which is in contact with the fixed seat 301; the other end of the anti-loosening sleeve 303 is provided with an anti-rotation bolt 304 for preventing a signal line from loosening, a through hole is radially formed in the anti-rotation bolt 304, a corresponding limiting hole is formed in the anti-loosening sleeve 303, and when the anti-rotation bolt 304 is rotated in place, the anti-rotation bolt 304 can be prevented from rotating relative to the anti-loosening sleeve 303 by screwing the through hole and the limiting hole through a fixing bolt.

According to data obtained by the bag-type pressure gauges at different positions, the synthesis and decomposition conditions of the hydrate can be detected through the difference of the differential pressure values between two side points, if the hydrate is formed or the hydrate in the area is not decomposed or the decomposition amount is less, the differential pressure value is high, otherwise, the differential pressure value is small, and therefore the synthesis condition of the reaction hydrate can be clearly known through the difference of the readings of the differential pressure values.

The hydrate synthesis and decomposition processes are monitored and detected by arranging high-precision temperature sensors at different positions, and if the hydrate synthesis or non-decomposition or decomposition amount is small, the temperature of the area is low, otherwise, the temperature is extremely high.

And detecting the resistivity values of different areas in the simulation process through the saturation electrodes, and calculating and detecting the saturation distribution conditions of the different areas according to the relation value between the resistivity and the saturation. If other measurement is required, the original measurement assembly 103 in the mounting hole 102 can be replaced or a corresponding measurement device can be added.

The constant temperature system 4 keeps the environmental temperature of the negative pressure sample cavity 1 during the experiment through a constant temperature box sleeved outside the negative pressure sample cavity 1; ambient temperature here refers to the temperature at the formation.

This vacuum system carries out the evacuation to negative pressure sample chamber 1 through the vacuum pump to avoid the air to remain in negative pressure sample chamber 1 and influence the effect of simulating actual reservoir.

The gas injection system 5 injects gas into the negative pressure sample chamber 1 through a gas compressor to synthesize hydrates or measure gas permeability of hydrate reservoirs in different production states. Such as by injecting isothermal single phase methane gas and accurately measuring the gas flow at the outlet and gas permeability according to darcy's law.

The liquid injection system 6 injects specified liquid into the negative pressure sample cavity 1 through a constant-speed constant-pressure pump, and is used for synthesizing hydrate by the current porous medium or analyzing the current liquid permeability of the porous medium. For example, by injecting isothermal water fluid and accurately measuring the liquid flow at the outlet, the liquid permeability can be measured according to Darcy's law.

The heat injection system 7 is used for injecting heat mass into the negative pressure sample cavity 1 to simulate the process of heat injection and exploitation of hydrate in the porous medium, so as to research water and gas migration in a hydrate formation and gas production of a hydrate reservoir under the conditions of pressure reduction and thermal exploitation, and further analyze the decomposition and migration states of the hydrate.

The drilling fluid circulating system 8 outputs the drilling fluid through the liquid storage device to realize annular circulation flow at the orifice of the negative pressure sample cavity 1 so as to simulate and analyze the influence and pollution of the drilling fluid on the conductive characteristics of a hydrate reservoir. The method can particularly simulate the influence of drilling fluid invasion on the conductivity of the hydrate formation under different conditions, and provides a basis for hydrate formation resistivity logging in the future.

The back pressure system 9 is used for controlling the gas pressure in the negative pressure sample cavity 1, performing gas-liquid separation on the fluid generated by the decomposition of the hydrate, and measuring the generated gas and liquid respectively.

The data acquisition and processing unit 10 includes a control system with data processing software, and the control system may be a PC, an industrial personal computer, or other equipment with data processing and analyzing functions. The control system controls the experiment process through data processing software and simultaneously realizes data acquisition, analysis and result output for different experiment processes.

In this scheme, negative pressure sample chamber 1, parameter measurement system 3 and data acquisition processing unit 10 constitute basic experimental structure, and other each systems communicate with negative pressure sample chamber 1 through corresponding pipeline simultaneously, and accessible data acquisition processing unit 10 is controlled alone when needs to realize different simulation processes, and when certain concrete process of simulation, other systems that need not participate in are kept apart by corresponding control valve.

During simulation, the permeability of different porous media can be measured by replacing different types of sediments, and various data in each simulation process can be analyzed and summarized by the existing analysis method, so that all data information of a selected reservoir in different simulation experiments is obtained, and a credible basis is provided for actual exploitation. The gas and liquid saturation in the pores of the porous medium can be calculated by accurately controlling the injection amount of gas and liquid entering the negative pressure sample cavity 1 and simultaneously accurately measuring the amount of gas and liquid at the outlet of the negative pressure sample cavity 1. By monitoring the generation conditions of hydrates at different positions in the negative pressure sample cavity 1 and the decomposition conditions of hydrates in the heat injection exploitation process, the changes of temperature and pressure curves in the porous medium in the experimental process can be analyzed, and the generation and decomposition of the hydrates can be determined according to the tiny difference of the gas phase and the temperature in the porous medium, so that the P-T balance and the decomposition conditions of the natural gas hydrates in different media can be obtained.

The embodiment simulates the decomposition process of the porous medium hydrate sample, and can realize dynamic characteristic determination and static characteristic determination, wherein the dynamic characteristic determination can be used for measuring and researching the dynamic changes of gas and water permeability, gas-water relative permeability and heat conductivity coefficient of different parts of the sediment-containing hydrate sample in the hydrate decomposition process under the condition of controlling the pressure reduction or heat injection decomposition of the hydrate sample. The static characteristic measurement can carry out in-situ measurement on gas and water permeability, gas-water relative permeability and heat conductivity of different parts of the synthesized hydrate sample containing sediments under the condition of controlling the hydrate sample not to be decomposed.

The whole system of the embodiment can simulate and synthesize different types of seabed hydrate deposition samples in situ, determine the porosity, the gas-water-hydrate saturation and the distribution characteristics of the hydrate samples in the synthesis process, and carry out in-situ measurement on the permeability and the heat conductivity coefficient of different types of sediments and different gas and water saturations.

The structure of each subsystem is described in detail below, each subsystem in the whole simulation system is communicated with the negative pressure sample cavity 1 through a main pipe or a corresponding branch pipe, and the data acquisition and processing unit 10 receives and controls the working process of each subsystem through a signal line, which can be implemented by any existing scheme, and is not described in the following description, and only the components and the interconnection relationship included in each subsystem are described.

The connection of the gas injection system 5 is schematically shown in fig. 3, and it includes an air compressor 501 for generating pressure gas, a gas booster pump 502 for boosting the gas generated by the air compressor 501, a low-pressure storage tank 503 for storing the low-pressure gas after boosting, a high-pressure storage tank 504 for storing the high-pressure gas after boosting, a pressure regulating valve 505 for inputting a specified pressure into the negative pressure sample chamber 1 by selecting the low-pressure storage tank 503 or the high-pressure storage tank 504 according to the experimental requirements, a flow controller 506 for controlling the flow of the output gas, and a cooler 508 for cooling the gas and liquid; a gas moistening device 507 is installed in the gas path before the pressure regulating valve 505, and the gas moistening device 507 is a pressure-resistant container filled with liquid and naturally moistens the gas passing through the pressure-resistant container.

The cooler 508 is used for cooling the gas and liquid injected into the negative pressure sample chamber 1, and the gas and liquid do not damage the equilibrium state of the hydrate in the negative pressure sample chamber 1 after cooling treatment.

The air compressor 501 can be a product with the model number of GCS50, the design pressure of the air compressor is 1.0MPa, the flow rate of the air compressor is 0.465m3/min, and the air compressor 501 can also be used for cleaning and scavenging the whole pipeline system.

The gas booster pump 502 may be selected from SITEC type gas booster pumps, model GBD60, boost ratio 60:1, maximum outlet pressure 498Bar, and maximum flow 40L/min.

The low-pressure storage tank 503 is mainly used for storing air pressurized by the air compressor 501, and needs to satisfy the following conditions: volume 0.1m³The working pressure is 0.8MPa, and the design pressure is 1 MPa. The high pressure tank 502 needs to satisfy the following: the volume is 2000mL, and the maximum working pressure is 50 MPa.

The pressure regulating valve 505 includes a manual pressure regulating valve and a corresponding pressure indicator, and is mainly used for adjusting the pressurized high-pressure gas (natural gas) to a required working pressure. The maximum inlet pressure of the manual pressure regulating valve is 50MPa, and the outlet pressure of the manual pressure regulating valve is adjustable between 0MPa and 40 MPa.

The flow controller 506 adopts a Brownian high-pressure flowmeter, the maximum working pressure of the flowmeter is 40MPa, and the flowmeter is provided with a communication interface and can be in communication connection with the data acquisition and processing unit 10.

The connection structure of the liquid injection system 6 is shown in fig. 4, and a constant-speed constant-pressure pump 601 of the liquid injection system 6 adopts an HAS-200HSB type double-cylinder constant-speed constant-pressure pump for quantitatively injecting a displacement medium and providing a power source for a test. The working pressure is 50MPa, the flow rate is 0.01-20 mL/min, the pressure protection and the position upper and lower limit protection are realized, the pump head material adopts 316L, the pump is provided with a communication port and can be connected with the data acquisition and processing unit 10, and the two cylinders can realize single-cylinder independent operation, double-cylinder independent operation and double-cylinder linkage operation. Distilled water or kerosene is used as a driving medium to be output, and the constant pressure, constant flow and tracking PLC control of the driving medium are realized in the output process.

Two pressure adjusting pistons 602 are installed in parallel between the double-cylinder constant-speed constant-pressure pump 601 and the negative pressure sample cavity 1, a four-way valve 603 is installed at each end of each pressure adjusting piston 602, and the four-way valve 603 can output gas and liquid and can be conveniently connected to other pipelines such as cleaning pipelines. The volume of the pressure regulating piston 602 is 2000mL, the working pressure is 50MPa, and the material is 316L. The pressure regulating piston 602 acts as an isolation and energy storage buffer and transfer for the injection fluid and the displacement fluid. The inner surface of the cylinder body is smoothened to reduce the friction force of the inner wall.

As shown in fig. 5, each pressure-regulating piston 602 includes a hollow container 6021 having both ends opened, an upper lid 6022 and a lower lid 6023 screwed to both ends of the hollow container 6021 via external threads, respectively, and a sealing plug 6024 mounted inside both ends of the hollow container 6021, respectively, a connection stand 6025 protruding outward is provided on a surface of the sealing plug 6024 facing away from the hollow container 6021, a through hole 6026 through which the connection stand 6025 passes is provided in the upper lid 6022 and the lower lid 6023, and an axial through hole 6027 is provided in the connection stand 6025; a partition plate 6028 which is axially movable and partitions the inside of the hollow container 6021 into two independent cavities is installed inside the hollow container 6021; one cavity is communicated with the double-cylinder constant-speed constant-pressure pump 601, the other cavity is communicated with the negative pressure sample cavity 1, a solution which is generated by a hydrate is filled in the cavity communicated with the negative pressure sample cavity 1, distilled water or kerosene is filled in the other cavity, and the distilled water or kerosene pushes the partition plate 6028 to move under the pressure of the double-cylinder constant-speed constant-pressure pump 601 so as to inject the solution in the other cavity into the negative pressure sample cavity 1.

Heating system 7 is including providing steam and hydrothermal steam generator 701 simultaneously, and steam generator 701 is including the inside cartridge heater that is provided with the heating chamber that is provided with, and the section of thick bamboo wall of cartridge heater is double-deck hollow structure, and the centre is hot water space, is provided with the heating pipe that annular or polygon directly communicate hot water space in the section of thick bamboo wall in the heating chamber, is provided with the heater in the below of heating pipe, and the usable electric heat mode of heater heats the heating pipe, makes its inside thermal mass become steam by liquid. A steam pipe for discharging steam generated in the heating pipe is arranged above the heating cylinder, and a cold water exchange area for adjusting the output temperature is arranged on an output channel of the steam pipe; the cold water exchange area regulates the temperature of the output steam through low-temperature water, wherein the low-temperature water can be water within a certain range, such as water with the temperature of 10 ℃, and can also be heat mass before entering a heating pipe, so that corresponding heat can be absorbed in advance to reduce the later-period heating time.

In addition, a temperature probe for detecting the temperature of each place, a pressure probe for detecting the input and output pressure, a water inlet pipe for supplying water to the hot water space and the cold water exchange area, a water outlet pipe for outputting steam and/or hot water, and a PLC control unit for controlling the output of predetermined steam or hot water according to instructions are further installed on the steam generator 701. The cold water exchange area can be communicated with the hot water space through a pipeline with a control valve so as to directly feed the heated cooling water into the heating pipe when needed.

As shown in fig. 6, the liquid storage device 8 specifically includes a liquid storage tank 801 for storing well fluid, a circulation pump 802 for controlling the circulation flow of the well fluid, a temperature controller 803 for heating the circulating well fluid, a pressure regulating device 804 for regulating the pressure of the well fluid during circulation, and a simulated wellhead annulus structure 805 arranged at the end of the negative pressure sample chamber 1.

An output port of the liquid storage tank 801 is connected with an inlet of the simulated wellhead annular structure 805 after being connected with the circulating pump 802, an outlet of the simulated wellhead annular structure 805 is connected with an input port of the liquid storage tank 801 after being connected with the pressure regulating device 804, the temperature controller 803 is separately connected with the liquid storage tank 801, and an output end of the circulating pump 802 is connected with the liquid storage pipe 801 through a branch pipe.

The liquid storage tank 801 is of a detachable structure with a cover, the volume is 1000mL, the maximum working pressure is 25MPa, and the temperature control range of the temperature controller 803 is about room temperature to 50 ℃. The maximum injection pressure of the circulating pump 802 is 25MPa, and the flow range is controlled to be 0.5-10 mL/min.

The inside heat preservation space for holding negative pressure sample chamber of thermostated container among this embodiment is provided with the hair-dryer that refrigerates and realize the interior hot-blast convection of box on the relative two sides in the inside of thermostated container, and the regulation wind gap of being connected with refrigerating system, has the heat preservation at the internally surface mounting of thermostated container, is provided with transparent observation window and temperature control panel on the box, is provided with the bearing frame that supports negative pressure sample chamber both ends in the box.

And when the constant temperature box works, the environment temperature of the negative pressure sample cavity is adjusted by utilizing the heating heat circulation system and the refrigerating cold circulation system. Temperature control range: -20 ℃ to 130 ℃, temperature control precision: . + -. 0.5 ℃.

The constant temperature box can also be connected with a heating system through a pipeline so as to realize mutual waste heat utilization.

As shown in fig. 7, the back pressure system 9 includes a back pressure valve 901 connected to a pipeline through which the hydrate is output from the negative pressure sample chamber 1, a back pressure gauge 902 for displaying a pressure on the back pressure valve 901, a back pressure pump 903 and a back pressure container 904 for adjusting the pressure at the back pressure valve 901 to be automatically released when the output pressure of the negative pressure sample chamber 1 exceeds a standard, a gas-liquid separator 905 for performing gas-liquid separation on the received hydrate, a gas tank 906 for receiving the separated gas and metering, and a weighing device 907 for weighing the separated liquid.

As shown in fig. 9, the bag-type pressure gauge 306 according to the present embodiment includes a pressure measuring tube 3061, a pressure measuring tube 3062 fitted around the outside of the pressure measuring tube 3061, a bag-type spacer 3063 located at the end of the pressure measuring tube 3062 and hermetically accommodating the end of the pressure measuring tube 3061, and an injection device for injecting an antifreeze into the pressure measuring tube 3062; the pressure measuring tube 3061 transmits the received pressure of the porous medium at the insertion position to an externally connected pressure sensor, and the pressure sensor directly displays the pressure through a self-provided digital display secondary meter or transmits the pressure to the data collecting and processing unit 10. The pressure tube 3062 serves to protect the pressure tube 3061, and the interior anti-freezing fluid may prevent the pressure tube 3061 from freezing by low temperatures at the porous medium. The bladder type spacer 3063 may form a pressurized cavity 3064 filled with anti-freeze fluid at the end of the pressure sensing tube 3061 to accurately transfer the applied pressure to the pressure sensing tube 3061.

The outer surface of the end of the pressure guiding pipe 3062 is provided with a plurality of radial convex rings 3065, the bag type isolation sleeve 3063 is a flexible sleeve with one end opened, the inner surface of the opening end is provided with a concave ring 3066 corresponding to the convex rings 3065, the bag type isolation sleeve 3063 is inserted and clamped with the convex rings 3065 on the pressure guiding pipe 3062 by the concave rings 3066, and a protection space for containing the anti-freezing solution can be formed inside while the anti-dropping is realized.

As shown in FIG. 10, the number of the mounting holes 102 on the negative pressure sample cavity 1 can be set according to the measurement precision and the measurement requirements of different positions, for example, 2-3 mounting holes 102 are set on the same radial direction of the negative pressure sample cavity in the present embodiment, each mounting hole 102 is distributed on the circumference of the negative pressure sample cavity 1 in a linear symmetry or triangular symmetry manner, and 8-12 mounting holes 102 can be set in the axial direction, and the number of the mounting holes 102 can be 16-36 as a whole.

In addition, at least 4 temperature sensors 307 can be arranged at one mounting hole 102, and each temperature sensor 307 in the same mounting hole 102 can be respectively positioned at 1/4, 2/4, 3/4 and the axle center of the radius line according to the distance from the inner side wall of the negative pressure sample cavity 1 to the axle center; similarly, the bladder pressure gauge 306 and the electrode 305 may be mounted in the same manner so that the pressure difference, the temperature difference, and the resistivity value difference in the axial direction of the porous medium can be measured. While at the same location, differential pressure, differential temperature and differential resistivity values at different depths can be measured.

As shown in fig. 2 and 11, in order to facilitate the detachment and sealing of the two ends of the negative pressure sample chamber 1, the sealing structure 104 of the negative pressure sample chamber 1 may include a flange 1041 fixed outside the nozzle at one end of the negative pressure sample chamber 1, and a sealing head 1042 movably sealing the open end of the nozzle, where the sealing head 1042 is used to plug the porous medium inside, and the flange 1041 is fixed at the nozzle of the negative pressure sample chamber 1 by a pressure-bearing screw while limiting the sealing head 1042 at the open end of the nozzle.

The end socket 1042 is provided with a plurality of axial through holes 1043 for connecting test pipelines of different systems, a sealing element is arranged at a position where the outer circumference of the end socket 1042 contacts with the inner side wall of the pipe orifice, a filter 1044 for isolation is arranged between the sealing element and the porous medium, and a diversion trench for dispersing liquid output by the axial through holes 1043 into surface output is arranged on the end face of the end face contacting with the porous medium, and the diversion trench comprises annular grooves 1045 annularly distributed on the end face at intervals and radial grooves 1046 for communicating the axial through holes 1043 with the annular grooves 1045, as shown in fig. 12.

During installation, after the porous medium is filled, the filter 1044 can be placed at the end of the porous medium, then the end cap 1042 is installed, and finally the flange 1041 is used to fix the whole end. The filter 1044 herein may comprise a filter paper and a metal screen, the filter paper being placed on the porous medium and the metal screen being placed thereon. The mesh size of the filter paper and metal screen is at least such that it prevents the passage of the porous medium but does not interfere with the passage of gas or liquid.

After entering the negative pressure sample chamber 1, the liquid or gas entering from the axial through hole 1042 on the end enclosure 1042 enters each annular groove 1045 through the radial groove 1046 on the end enclosure 1042, and then enters the porous medium in a surface form through the filter 1044, so that the gas or liquid can uniformly contact with the porous medium, and the actual formation condition is simulated really.

As shown in fig. 13, a loading chamber 1052 for accommodating the axial pressure loading piston 1051 is installed at the other end of the negative pressure sample chamber 1, the axial pressure loading piston 1051 is inserted into the loading chamber 1052 and can move along the axial direction of the loading chamber 1052, the outer circumference of the axial pressure loading piston 1051 has the same diameter as the inner circumference of the negative pressure sample chamber 1, a filter 1044 for preventing the porous medium from passing through is also arranged between the end face of the axial pressure loading piston 1051 and the porous medium, and the end of the loading chamber 1052 far away from the negative pressure sample chamber 1 limits the axial pressure loading piston 1051 in the loading chamber 1052 through a sealing gland 1053.

The axial pressure loading piston 1051 moves axially inside the loading chamber 1052 under hydraulic or mechanical pressure, applying axial pressure to the porous media to simulate formation pressure at the actual reservoir for the porous media.

In an embodiment of the present invention, a steady-state measuring device 103 for realizing a steady-state hot wire measurement is further disposed in the negative pressure sample chamber 1, and the steady-state measuring device 103 includes a platinum hot wire 1031 inserted in the negative pressure sample chamber 1 and located on an axial line, a sheath 1032 covering the platinum hot wire, a sealing head 104 fixing two ends of the sheath 1032 and the platinum hot wire 1031 to two ends of the negative pressure sample chamber 1, and a fixing seat 1033 fixing two ends of the platinum hot wire 1031 to the axial pressure loading piston 1051.

After the platinum hot wire 1051 is electrified, the porous medium hot wire 1051 can be heated from the axial line of the porous medium and advances towards the circumferential direction, the sheath 1052 can prevent external liquid or the porous medium from directly contacting with the platinum hot wire 1031, the temperature rise rate can be measured through the temperature sensors 307 arranged at different positions and different depths of the porous medium, and then the heat conductivity coefficient of the hydrate can be tested.

As shown in fig. 14, the specific fixing seat structure is as follows: the fixing seat 1033 is a cylindrical structure, an axial through hole is arranged inside the fixing seat 1033, external threads are arranged at two ends of the fixing seat 1033, the fixing seat is connected with the end socket 1042 or a mounting hole on the axial compression loading piston 1051 through the external thread at one end, a sealing press ring 1034 which deforms after being extruded to enhance the sealing effect is arranged in the mounting hole, a tensioning joint 1035 is screwed on the external thread at the other end of the fixing seat 1033, an adjusting nut 1036 which is used for adjusting the tensioning degree of the tensioning joint 1035 is arranged at one end, close to the fixing seat 1033, of the tensioning joint 1035, an inverted wedge squeezing ring 1037 with a groove is arranged in the end at the other end of the tensioning joint 1035, and a tightening press cap 1038 which limits the inverted wedge squeezing ring 103.

The tightness of the platinum wire 1031 can be adjusted by tightening the joint 1035 without affecting the fixing effect of the tightening cap 1038.

In order to facilitate the observation of the simulation process and the use of observation equipment, symmetrical observation windows are arranged on two opposite sides of the negative pressure sample cavity, and sapphire glass facilitating infrared direct observation is arranged on the observation window 104.

In one embodiment of the present invention, an experimental method of the aforementioned experimental system is disclosed, which generally comprises the following steps:

step 100, selectively connecting corresponding equipment with a negative pressure sample cavity according to test requirements, opening one end of a sealing structure of the negative pressure sample cavity, filling a wet porous medium sample in a vertical mode, placing a metal net and filter paper which do not influence the passing of water vapor but prevent the sample from passing between the sample and the sealing structure and a shaft pressure loading piston, locking the sealing structure after filling, and horizontally placing the negative pressure sample cavity;

the corresponding equipment connection can be that all systems for different simulation effects are connected at the same time, and then the corresponding systems are opened according to requirements, or the systems only with corresponding requirements are installed. Care needs to be taken to close and seal the control valves when connecting the systems.

Step 200, connecting a parameter measuring system, vacuumizing a negative pressure sample cavity through a vacuum system, then adding ring pressure, starting a constant temperature system to simulate the required environment temperature of the experiment, and then simulating the corresponding stratum environment through starting different systems to carry out the corresponding experiment, wherein the purpose of the experiment comprises:

injecting natural gas or gas in different phases into a current sample through a gas injection system to analyze the permeability and porosity of the current sample under different ring pressures and different water saturation degrees;

injecting liquid, and then injecting gas with certain pressure, reducing the experiment temperature, and realizing hydrate synthesis;

thirdly, simulating the hydrate decomposition process by reducing the system pressure, and observing the distribution characteristics of the synthesized hydrate sample through a sapphire window;

fourthly, measuring the porosity, the permeability and the gas-water relative permeability of the reservoir at different stages of hydrate decomposition;

enabling the drilling fluid to circularly flow along the simulated wellhead annulus structure of the negative pressure sample cavity through a well fluid circulating system, and simultaneously measuring the influence state of the sample on the penetration of the drilling fluid;

injecting hot gas or hot water into the sample through a heating system to measure the decomposition state of the hydrate in a heat injection exploitation mode;

the experimental purposes in the step do not need to be realized simultaneously, and can be respectively carried out according to the experimental purposes.

Step 300, measuring pressure difference value data of a sample in the axial direction by a bag-type pressure gauge in a parameter measuring system, measuring temperature change of hydrate in the sample during generation and decomposition by a temperature sensor, measuring resistivity values of different positions and different depths at the same position in the axial direction of the sample by electrodes, and obtaining saturation distribution conditions of different areas of the sample by a relation value between the resistivity and the saturation; obtaining single-phase and multi-phase permeability of the current seabed hydrate reservoir argillaceous silt porous medium through an inlet-outlet gas flowmeter and a liquid flowmeter;

and 400, in the experiment process, the back pressure system adjusts the displacement pressure required in each experiment process by controlling the output pressure of the negative pressure sample cavity, and the processing unit controls the processing steps, data acquisition and output analysis results of each experiment process.

The method can realize different simulation experiment processes through different system combinations or independently, determine the permeability of different porous media by changing different types of sediments, and analyze and summarize various data in each simulation process through the existing analysis method, so that all data information of a selected reservoir in different simulation experiments is obtained, and a credible basis is provided for actual exploitation. The gas and liquid saturation in the pores of the porous medium can be calculated by accurately controlling the injection amount of gas and liquid entering the rectangular simulation cavity and simultaneously accurately measuring the amount of gas and liquid at the outlet of the rectangular simulation cavity. By monitoring the generation conditions of hydrates at different positions in the negative pressure sample cavity and the decomposition conditions of hydrates in the heat injection exploitation process, the changes of temperature and pressure curves in the porous medium in the experimental process can be analyzed, and the generation and decomposition of the hydrates are determined according to the tiny difference of the gas phase and the temperature in the porous medium, so that the P-T balance and the decomposition conditions of the natural gas hydrates in different media are obtained.

The process of each simulation experiment is the same as that of the simulation system described above and will not be repeated here.

Thus, it should be appreciated by those skilled in the art that while a number of exemplary embodiments of the invention have been illustrated and described in detail herein, many other variations or modifications consistent with the principles of the invention may be directly determined or derived from the disclosure of the present invention without departing from the spirit and scope of the invention. Accordingly, the scope of the invention should be understood and interpreted to cover all such other variations or modifications.

Claims

1. A comprehensive hydrate modeling system, comprising:

the data acquisition and processing unit comprises a control system with data processing software, and realizes data acquisition, analysis and result output for different experimental processes while controlling the experimental processes;

the constant-speed constant-pressure pump of the liquid injection system is a double-cylinder constant-speed constant-pressure pump, the double-cylinder constant-speed constant-pressure pump realizes single-cylinder independent operation, double-cylinder independent operation and double-cylinder linkage operation through two cylinders, distilled water or kerosene is used as a driving medium to be output, and the constant-pressure constant-flow and tracking PLC control over the driving medium is realized in the output process;

2. The comprehensive hydrate modeling system of claim 1,

the gas injection system comprises an air compressor for generating pressure gas, a gas booster pump for boosting the gas generated by the air compressor, a low-pressure storage tank for storing the boosted low-pressure gas, a high-pressure storage tank for storing the boosted high-pressure gas, a pressure regulating valve for inputting specified pressure into the negative pressure sample cavity from the low-pressure storage tank or the high-pressure storage tank according to experimental requirements, a flow controller for controlling the flow of the output gas, and a cooler for cooling the injected gas and liquid; and a gas wetting device is arranged on a gas path before the pressure reducing valve, and is a pressure-resistant container filled with liquid.

3. The comprehensive hydrate modeling system of claim 1,

the heat injection system comprises a steam generator which simultaneously provides steam and hot water, the steam generator comprises a heating barrel, a heating cavity is arranged in the heating barrel, the barrel wall of the heating barrel is of a double-layer hollow structure, a hot water space is arranged in the middle of the heating barrel, an annular or polygonal heating pipe which is directly communicated with the hot water space in the barrel wall is arranged in the heating cavity, a heater is arranged below the heating pipe, a steam pipe for discharging the steam generated in the heating pipe is arranged above the heating pipe, and a cold water exchange area for adjusting the output temperature is arranged on an output channel of the steam pipe;

4. The comprehensive hydrate modeling system of claim 3,

the inside heat preservation space for holding negative pressure sample chamber of thermostated container is provided with the hair-dryer of refrigeration and realization box internal hot-blast convection current on the relative two sides in the inside of thermostated container, the regulation wind gap of being connected with refrigerating system, the internally mounted surface of thermostated container has the heat preservation, is provided with transparent observation window and temperature control panel on the box, is provided with the bearing frame that supports negative pressure sample chamber both ends in the box.

5. The comprehensive hydrate modeling system of claim 4,

the constant temperature box is connected with a heating system through a pipeline so as to realize mutual waste heat utilization.

6. The comprehensive hydrate modeling system of claim 1,

the liquid storage device comprises a liquid storage tank for storing well liquid, a circulating pump for controlling the well liquid to flow circularly, a temperature controller for heating the circulating well liquid, a pressure regulating device for regulating the pressure during the circulation of the well liquid, and a simulated wellhead annular structure arranged at the end part of the negative pressure sample cavity;

7. The comprehensive hydrate modeling system of claim 1,

the limiting sheets are installed in a plurality, and the limiting sheets are installed at intervals or in contact with each other.

8. The comprehensive hydrate modeling system of claim 1,

the bag-type pressure gauge comprises a pressure measuring pipe, a pressure measuring pipe sleeved outside the pressure measuring pipe, a bag-type isolation sleeve positioned at the end part of the pressure measuring pipe and used for hermetically containing the end part of the pressure measuring pipe, and an injection device for injecting an antifreezing solution into the pressure measuring pipe; the tip surface of the pressure pipe is provided with the radial bulge loop of multichannel, bag formula isolation sleeve is one end open-ended flexible cover, is provided with the concave ring that corresponds with the bulge loop at the internal surface of open end, bag formula isolation sleeve utilize the concave ring with link together after the bulge loop block on the pressure pipe, form the protection space who holds the antifreeze in inside.

9. The comprehensive hydrate modeling system of claim 1,

the same radial ascending mounting hole of negative pressure sample chamber distributes with sharp symmetry or triangle symmetry mode on the circumference of negative pressure sample chamber, the quantity of mounting hole is 8~12, one mounting hole department temperature sensor is provided with 4 at least, and is located respectively 1/4, 2/4, 3/4 and the axle center department of the radius line in negative pressure sample chamber.

10. The comprehensive hydrate modeling system of claim 1,

the sealing structure of the negative pressure sample cavity comprises a flange fixed at a pipe orifice at one end and an end enclosure movably sealing the opening end of the pipe orifice, and the flange is fixed at the pipe orifice through a pressure-bearing screw and limits the end enclosure at the opening end of the pipe orifice; the end socket is provided with a plurality of axial through holes for connecting a test pipeline, a sealing element is arranged at the position where the outer circumference of the end socket is contacted with the inner side wall of the pipe orifice, a filter for isolation is arranged between the end socket and the porous medium, meanwhile, a flow guide groove for dispersing liquid output by the axial through holes into surface output is arranged on the end surface of one end contacted with the porous medium, and the flow guide groove comprises annular grooves which are distributed on the end surface at intervals in an annular mode and radial grooves which are communicated with the axial through holes and the annular grooves.

11. The comprehensive hydrate modeling system of claim 10,

the loading cavity is arranged at the other end of the negative pressure sample cavity, the axial pressure loading piston is inserted into the loading cavity, the diameter of the outer circumference of the axial pressure loading piston is the same as that of the inner circumference of the negative pressure sample cavity, a filter for preventing the porous medium from passing through is arranged between the end surface of the axial pressure loading piston and the porous medium, and the axial pressure loading piston is limited in the loading cavity through a sealing gland at one end of the loading cavity, which is opposite to the end connected with the negative pressure sample cavity.

12. The comprehensive hydrate modeling system of claim 10,

a steady-state measuring device for realizing steady-state hot wire measurement is arranged in the negative pressure sample cavity, and comprises a platinum hot wire inserted in the negative pressure sample cavity and positioned on an axial lead, a sheath sleeved outside the platinum hot wire, and sealing heads for fixing the two ends of the sheath and the platinum hot wire on the two ends of the negative pressure sample cavity and a fixing seat on an axial pressure loading piston;

13. The comprehensive hydrate modeling system of claim 1,

the back pressure system comprises a back pressure valve connected to a pipeline for outputting the hydrate from the negative pressure sample cavity, a back pressure meter for displaying the pressure on the back pressure valve, a back pressure pump and a back pressure container for adjusting the pressure at the back pressure valve to automatically release the pressure when the output pressure of the negative pressure sample cavity exceeds the standard, a gas-liquid separator for performing gas-liquid separation on the received hydrate, a gas tank for receiving and metering the separated gas, and a weighing device for weighing the separated liquid.

14. The comprehensive hydrate modeling system of claim 1,

the sapphire visual windows are oppositely arranged on two sides of the negative pressure sample cavity.

15. The comprehensive hydrate modeling system of claim 1,

the displacement pressure borne by the negative pressure sample cavity in the experiment is more than or equal to 14MPa, and the ring pressure is more than or equal to 40 MPa.