Staged parallel high-pressure gas constant-pressure adsorption / desorption test device and method

Abstract

The invention discloses a staged parallel high-pressure gas constant-pressure adsorption / desorption test device and method, and belongs to the technical field of deep reservoir structure performance testing. The test device comprises a gas preparation and supply system, a gas preparation prefabricating kettle, a constant-volume piston reference kettle, a stage type parallel sample kettle, a vacuumizing system, a waste gas buffer system, an experimental gas safety monitoring and alarming system and a terminal operation and real-time data monitoring system. According to the invention, the adsorption capacity of a deep reservoir structure material to single-component or multi-component high-pressure gas at high temperature and high pressure is studied by connecting 50mL constant-volume small-volume sample inner kettles in parallel, and stage structure analysis of an adsorption experiment between the high-pressure gas and the reservoir structure material is realized in a series of high-pressure adsorption experiment processes; the change of the adsorption capacity of the high-pressure adsorbate and the adsorbent in the multi-pressure-value adsorption experiment process and the structural change of the adsorbent with the staged specific pressure value can be more accurately carried out, and technical reference is provided for deep gas storage and the like.

Description

Technical Field

[0001] The invention relates to a stage-type parallel high-pressure gas constant-pressure adsorption / desorption test device and method, belonging to the technical field of deep reservoir structure performance testing. Background Art

[0002] Currently, carbon capture and storage (CCUS) is a key solution to reduce greenhouse gas emissions. Among them, the main places for geological storage include depleted oil and gas reservoirs, saline aquifers and deep unmineable coal seams. The gas storage environment in deep reservoirs is characterized by high temperature, high pressure and high ground stress. The adsorption and desorption characteristics of stored gas can be used to predict the storage capacity of reservoirs and evaluate reservoir stability and safety.

[0003] Taking carbon sequestration as an example, during the sequestration process, the injected carbon dioxide is in a high-pressure state. When the temperature reaches a critical point, it turns into supercritical carbon dioxide (ScCO2). Deep coal seams have a strong adsorption effect on supercritical carbon dioxide, and ScCO2 has a strong extraction effect on coal-based organic matter.

[0004] Existing studies mostly used immersion methods, and lacked structural analysis of characteristic pressure points in the overall process.

[0005] In the prior art, the study on the effect of material structure under the action of high-pressure gas mainly analyzes the material structure of samples before and after high-pressure immersion and isothermal adsorption experiments. There is a lack of measurement and analysis of the adsorption amount, adsorption capacity and pore structure changes of the coal body in the overall process and the material structure under specific pressure. Therefore, studying the physical and chemical structure characteristics of the coal body under specific pressure during the whole process of quantitative constant pressure adsorption of reservoir / adsorbent materials under high temperature and high pressure conditions is of great significance to exploring the structural stability and safety of the entire process of gas sealing in deep reservoirs. Summary of the invention

[0006] In order to overcome the above-mentioned shortcomings, the present invention provides a stage-type parallel high-pressure gas constant-pressure adsorption / desorption test device and method, which realizes the corresponding analysis of the adsorption amount and the experimental material structure at a specific pressure value in the whole process of high-pressure gas constant-pressure adsorption / desorption under simulated deep conditions, and solves the problem that in the traditional full-process adsorption experiment, the structure of the material to be tested can only be analyzed twice before and after the experiment, and a stage-by-stage study on its structure cannot be carried out.

[0007] The experimental device provided by the present invention mainly studies the adsorption capacity of deep reservoir structural materials for high-pressure gas under high temperature and high pressure (reservoir depth>800m, formation environment temperature 30-100℃, pressure 0-50MPa), and realizes the stage-by-stage structural analysis of the adsorption test between the adsorbed gas and the reservoir structural material in a series of high-pressure adsorption experiments. It can more accurately carry out the adsorption amount and the adsorbent structure changes of the stage-by-stage specific pressure values ​​in the multi-pressure point adsorption experiment of high-pressure adsorbent and adsorbent, and provide technical reference for deep gas sealing, etc. The present invention can not only determine the adsorption amount of gas by structural materials (coal body) in adsorption experiments by connecting multiple groups of 50mL fixed-volume small-volume sample kettles in parallel, but also realize the structural evolution of the material to be tested under specific pressure values ​​by disassembling the sample kettle, calculating the residual free volume of the experiment and characterizing the material structure by multiple means, and then study the relationship and law between the adsorption capacity of the material structure and the change of the pore structure under specific pressure values ​​in the whole process adsorption experiment; further, the device can also carry out corresponding analysis of the adsorption amount and the experimental material structure under specific pressure values ​​in the whole process of constant-pressure adsorption / desorption of single-component or multi-component gases, and without affecting the overall whole process experimental conditions, the detachable device can be used to characterize and analyze the structure of the experimental material.

[0008] The environment simulated by the present invention is deep high temperature and high pressure conditions. The high temperature condition is achieved by setting a constant temperature box. The constant temperature box is a closed box with a maximum temperature of 150°C. During the experiment, the gas distribution prefabricated kettle, the constant volume piston reference kettle, and the stage-type parallel sample kettle set in the constant temperature box are continuously heated as needed, and cyclic heating is performed after stabilization to ensure the temperature stability of the kettle body; the high pressure condition is achieved through a gas supply system and a gas distribution prefabricated kettle. The high pressure gas is injected into the gas distribution prefabricated kettle, and then injected into the constant volume piston reference kettle for experiment after it is stabilized.

[0009] The present invention provides a staged parallel high-pressure gas constant-pressure adsorption / desorption test device, which is used to simulate the corresponding analysis of the adsorption amount and the experimental material structure at a specific pressure value during the whole process of single-component or multi-component gas constant-pressure adsorption / desorption under high-temperature and high-pressure conditions in deep reservoirs, and the detachable device can characterize and analyze the structure of the experimental material without affecting the overall experimental conditions of the whole process. The test device includes: a gas preparation and supply system, a gas preparation kettle, a constant-volume piston reference kettle, a staged parallel sample kettle, a vacuum system, an exhaust gas buffer system, an experimental gas safety monitoring and alarm system, and a terminal operation and real-time data monitoring system;

[0010] The gas preparation and supply system is used to prepare and supply gas for the entire stage-type parallel high-pressure gas constant-pressure adsorption / desorption test device. The gas preparation and supply system includes a gas cylinder, a pneumatic valve, a one-way ball valve, an automatic high-pressure needle valve and a filter connected in sequence. The outlet end of the filter is connected to a gas booster pump for gas pressurization. The outlet of the booster pump is connected to multiple groups of gas distribution control modules; the gas preparation and supply system is connected to the gas distribution prefabricated kettle through a pipeline;

[0011] A gas distribution prefabricated kettle, a constant volume piston reference kettle and a staged parallel sample kettle are arranged in a constant temperature box; the tops of the gas distribution prefabricated kettle, the constant volume piston reference kettle and the staged parallel sample kettle are connected to each other through pipelines; a 1mL piston buffer tube is arranged at the bottom of the gas distribution prefabricated kettle and is connected to a gas chromatograph; the bottom of the constant volume piston reference kettle is connected to a liquid pressure gauge, a liquid storage tank and a precision double-cylinder injection pump; the staged parallel sample kettle comprises a cylindrical outer kettle and six groups of constant volume small volume sample inner kettles evenly arranged in the kettle, and the mass of the sample to be tested is placed in the small volume sample inner kettle, a sample kettle temperature and pressure sensor is arranged on the top of the cylindrical outer kettle of the staged parallel sample kettle, and a safety valve and a first-level automatic high-pressure connecting needle valve are provided on the top of the outer kettle of the staged parallel sample kettle; a second-level automatic high-pressure connecting needle valve is provided on the top of each small volume sample inner kettle; The inner kettle of the staged parallel sample kettle is composed of six groups of detachable 50mL fixed-volume small-volume sample inner kettles connected in parallel. A 1mL piston buffer tube is set on the top of each small-volume sample inner kettle to collect the adsorbed gas in the kettle according to the experimental requirements; during the experiment, helium and a two-stage automatic high-pressure connecting needle valve are used to perform multi-stage residual free volume determination to achieve calibration and closure of the volume of each parallel sample kettle after sample loading to avoid affecting the entire adsorption experiment process; six groups of detachable 50mL fixed-volume small-volume sample inner kettles are connected in parallel to achieve staged structural analysis of the adsorption experiment between the adsorbed gas and the adsorbent material during a series of high-pressure adsorption experiments, which can more accurately carry out the adsorption amount and stage-specific pressure value changes of the adsorbent structure of the high-pressure adsorbed gas and the adsorbent material during the multi-pressure point adsorption experiment;

[0012] The terminal operation and real-time data monitoring system includes a temperature and pressure data acquisition and processing system and a computer. The temperature and pressure data acquisition and processing system sends data to the computer in real time through a data transmission line. The computer is used to record the pressure and temperature data values ​​and draw change curves respectively; the temperature and pressure data acquisition and processing system includes a data transmission line and a signal converter; the pressure sensor of the gas distribution prefabrication kettle, the temperature and pressure sensor of the sample kettle, and the temperature and pressure sensor of the reference kettle are all connected to the signal converter of the temperature and pressure data acquisition and processing system through a data transmission line;

[0013] An experimental gas safety monitoring and alarm system, which is electrically connected to a computer and includes an experimental gas safety alarm module and an experimental gas concentration probe, wherein the experimental gas concentration probe is used to measure the experimental gas concentration in the constant temperature box, and the experimental gas safety alarm module is used to alarm when the experimental gas concentration measured by the experimental gas concentration probe is higher than a set safety value;

[0014] The vacuum system and the waste gas buffer system are connected to the two passages of the six-way regulating valve respectively, without interfering with each other; the gas distribution prefabricated kettle, the constant volume piston reference kettle and the stage-type parallel sample kettle are connected to the vacuum system through pipelines, and the pipelines are provided with vacuum valves and six-way regulating valves. The vacuum system includes a vacuum gauge, a dryer and a vacuum pump; the waste gas buffer system includes a waste gas treatment chamber; by controlling the vacuum valve, the vacuum environment of the gas distribution prefabricated kettle, the constant volume piston reference kettle and the stage-type parallel sample kettle is realized. The vacuum gauge, the dryer and the vacuum pump are connected in sequence to one passage of the six-way regulating valve, and the waste gas treatment chamber is connected to the other passage.

[0015] Furthermore, a fine-tuning valve and a filter are provided on the connecting pipeline between the gas distribution prefabrication kettle and the constant volume piston reference kettle; on the pipeline connecting the gas distribution prefabrication kettle and the stage-type parallel sample kettle, a pressure sensor is connected to the top of the kettle body of the gas distribution prefabrication kettle, and a sample kettle temperature and pressure sensor is connected to the top of the outer kettle of the stage-type parallel sample kettle; a first-level automatic high-pressure connecting needle valve is provided on the connecting pipeline between the constant volume piston reference kettle and the outer kettle of the stage-type parallel sample kettle; a reference kettle temperature and pressure sensor is connected to the top of the constant volume piston reference kettle; the pressure sensor of the gas distribution prefabrication kettle, the sample kettle temperature and pressure sensor, and the reference kettle temperature and pressure sensor are all connected to the signal converter of the temperature and pressure data acquisition and processing system through a data transmission line.

[0016] Furthermore, the gas distribution supply system includes several gas cylinders for storing helium and the same or different types of experimental gases; an air intake assembly is installed at the gas outlet end of the gas cylinder, and the air intake assembly includes a pneumatic valve, a one-way ball valve and an automatic high-pressure needle valve arranged in sequence on the gas path. The experimental gas passes through the air intake assembly and then through a filter and finally enters the gas distribution prefabricated kettle.

[0017] Furthermore, one passage of the six-way regulating valve is connected to a vacuum gauge, a dryer and a vacuum pump in sequence, and another passage is connected to the exhaust gas treatment chamber.

[0018] Furthermore, the experimental gas concentration probes are arranged at the upper, middle and lower positions of the side wall of the constant temperature box, and there are three groups of probes in total. The probes are connected by two-wire pluggable connections, and the type of probes is selected according to the experimental requirements.

[0019] Furthermore, a gas-sensitive electrode is provided on each small-volume sample inner kettle in the constant-volume piston reference kettle and the staged parallel sample kettle, and two sets of internal and external connecting joints are provided on the side wall of the staged parallel sample kettle. The corresponding two connecting pipes are respectively connected to the gas chromatograph and the precise small-scale liquid injection pump; a 1mL piston buffer tube is provided on the connecting pipe between the precise small-scale liquid injection pump and the small-volume sample inner kettle. Liquid is injected through the precise small-scale liquid injection pump, and the piston is pushed to directly enter the gas chromatograph to detect the adsorbate gas in the experimental sample.

[0020] Furthermore, the inner kettles of the fixed-volume small-volume samples are all made of 316L stainless steel that is resistant to high temperature and high pressure and is used to place test samples with a pressure resistance of 60MPa.

[0021] The present invention provides a staged parallel high-pressure gas constant-pressure adsorption / desorption test method, using the above-mentioned staged parallel high-pressure gas constant-pressure adsorption / desorption test device, the method comprises the following steps:

[0022] Step 1: Prepare single-component or multi-component experimental gas: Before conducting the adsorption test, first prepare the required concentration and component adsorbent gas through the gas preparation supply system and the gas preparation kettle. Based on the real gas state equation, the required gas preparation ratio is achieved by controlling the gas pressure. For multi-component gases, the gas preparation sequence is based on the molar concentration from small to large. The whole process needs to maintain constant temperature. The calculation equation is as follows: PV = Z 混合气 n 总 RT, where P is the gas pressure, MPa; V is the volume of the gas prefabricated kettle, cm 3 ; Z is the compressibility factor of the mixed gas; n is the total amount of substance in the mixed gas, mol; R is the gas universal constant, 8.314 J / (mol·K); T is the experimental environment temperature, K; n i =a i ×n 总 Where n i is the amount of substance of component i of the mixed gas, mol; a i is the molar concentration of component i, %; n 总 is the total amount of substance in the mixer, mol;

[0023] Step 2: Sample pretreatment: Before conducting the isothermal adsorption experiment, the experimental samples are first divided into six groups for particle size screening and weighing, and then the samples to be tested are subjected to balanced water treatment or drying treatment according to the experimental requirements. The samples are placed in a vacuum blower at 105°C and dried for 12 hours. After weighing again, the six groups of samples of equal mass are placed in six groups of small volume sample inner kettles;

[0024] Step 3, calibrate the volume of the constant volume piston reference kettle; evacuate the entire experimental system, place the piston plate of the inner cavity of the constant volume piston reference kettle at the bottom, fill the constant volume piston reference kettle with high pressure helium, and record the equilibrium pressure and temperature in the kettle after reaching equilibrium; open the second automatic high pressure connecting needle valve to inject helium into the staged parallel sample kettle, and record the equilibrium pressure and temperature after the constant volume piston reference kettle and the staged parallel sample kettle are both adsorbed and balanced, calculate the full scale of the constant volume piston reference kettle and the total volume of the staged parallel sample kettle cavity, and according to the law of conservation of mass and the ideal gas state equation PV = nZRT, the calculation formula is as follows: Where P R is the initial equilibrium pressure in the constant volume piston reference kettle, MPa; M He is the relative molecular mass of helium, g / mol; Z R is the initial equilibrium pressure P in the constant volume piston reference kettle R Helium compression factor under R is the volume of the constant volume piston reference kettle, cm 3 ;P S V is the equilibrium pressure after the constant volume piston reference kettle and the staged parallel sample kettle are connected, MPa; S is the total volume of the six sample kettles in parallel in a staged manner, cm 3 ; Z S It is the equilibrium pressure P after the constant volume piston reference kettle and the stage type parallel sample kettle are connected. S The helium compression factor under ; R is the gas universal constant, 8.314 J / (mol·K); T is the experimental environment temperature, K;

[0025] Place a standard block with a volume of V0 in the sample kettle and repeat the helium volume calibration operation. According to the law of mass conservation, the calculation formula is as follows: Combine the volume calibration equations before and after the standard block is placed to obtain the full-scale volume of the constant-volume piston reference kettle;

[0026] Step 4, determination of the total residual free volume of the staged parallel sample kettles; evacuate the entire device, fill the constant volume piston reference kettle with helium, stop gas injection after adsorption equilibrium, and record the equilibrium pressure and temperature in the constant volume piston reference kettle; then open the first-level automatic high-pressure connecting needle valve and all the second-level automatic high-pressure connecting needle valves to inject gas into the kettles of the six groups of sample kettles, record the equilibrium pressure and temperature after the constant volume piston reference kettle and the sample kettle are both adsorbed and balanced, calculate the total residual free volume in the sample kettle, and according to the law of conservation of mass and the ideal gas state equation PV = nZRT, the calculation formula is as follows: Where P R is the initial equilibrium pressure in the constant volume piston reference kettle, MPa; M He is the relative molecular mass of helium, g / mol; Z Ris the initial equilibrium pressure P in the constant volume piston reference kettle R Helium compression factor under R is the volume of the constant volume piston reference kettle, cm 3 ;P S V is the equilibrium pressure after the constant volume piston reference kettle and the sample kettle are connected, MPa; fTotal is the total volume of the six sample kettles, cm 3 ; Z S It is the equilibrium pressure P after the constant volume piston reference kettle and the sample kettle are connected S The helium compression factor under ; R is the gas universal constant, 8.314 J / (mol·K); T is the experimental environment temperature, K;

[0027] Step 5. Determine the remaining free volume of each of the six parallel sample kettles; by closing the No. 1, 2, 3, 4, and 5 secondary automatic high-pressure connecting needle valves in sequence, repeat step 2 for five times to determine the helium volume. The calculation formula is as follows: V f The value decreases with the gradual closing of the secondary automatic high-pressure connecting needle valves No. 1, 2, 3, 4, and 5; i is the number of six sets of parallel sample kettles that need to be disassembled, pieces; V fi is the remaining free volume of the i-th constant volume small volume sample inner kettle, cm 3 ; V f is the total remaining free volume in the sample kettle after disassembly, cm 3 ; n represents the number of kettles in the disassembled small volume sample, V fTofal Represents the total volume of the kettle in six groups of small volume samples, cm 3 ;

[0028] Step 6, high-pressure gas isothermal adsorption experiment; evacuate the gas distribution prefabricated kettle, the constant volume, constant pressure, constant volume piston reference kettle and the staged parallel sample kettle for 1 hour, close all valves, and set the experimental target temperature through the thermostat temperature control system; inject high-pressure gas into the gas distribution prefabricated kettle, and observe the temperature and pressure values; when the pressure fluctuation range is less than 0.1psi / h and the temperature fluctuation range is less than 0.025℃ / h, the state value is used as the standard value for measuring equilibrium, open the fine-tuning valve, inject gas into the constant volume piston reference kettle, record the equilibrium pressure and temperature of the constant volume piston reference kettle, and when the pressure and temperature reach equilibrium, open one The first and second level automatic high-pressure connecting needle valves and the liquid automatic high-pressure connecting valve push the piston plate to change the volume of the lower chamber of the constant-volume piston reference kettle according to the set pressure value through the precision double-cylinder injection pump, and inject the gas in the upper chamber of the constant-volume piston reference kettle into the six sets of parallel sample kettles at the same time. When the pressure in the sample kettle reaches the set value, the first level automatic high-pressure connecting needle valve is closed to wait for adsorption equilibrium. In this process, the temperature and pressure data acquisition and processing system collects the gas pressure and temperature in the constant-volume piston reference kettle and the sample kettle. When the system pressure fluctuation range and temperature fluctuation range reach the equilibrium standard, it is considered that the adsorption experiment under the adsorption pressure is completed.

[0029] Step 7. After the last pressure adsorption experiment is completed, open the first-level automatic high-pressure connecting needle valve and the liquid automatic high-pressure connecting valve between the constant volume piston reference kettle and the sample kettle again, and gradually increase the pressure by 1MPa to carry out the next adsorption pressure experiment until all adsorption pressure experiments are completed. According to the law of conservation of mass, the formula for calculating the adsorption amount of the adsorption process of one experimental pressure value is as follows: Wherein, m is the mass of the sample to be tested in the experiment, g; R is the universal gas constant, 8.314 J / (mol·K); T is the experimental environment temperature, K; P1 and P2 are the initial equilibrium pressures of the constant volume piston reference kettle and the staged parallel sample kettle, MPa; P3 and P4 are the equilibrium pressures of the constant volume piston reference kettle and the staged parallel sample kettle with the connecting valve opened to achieve pressure equilibrium, MPa; Z1 and Z2 are the gas compression factors at the initial equilibrium pressures P1 and P2 of the constant volume piston reference kettle and the staged parallel sample kettle, respectively; Z3 and Z4 are the gas compression factors at the equilibrium pressures P3 and P4 of the constant volume piston reference kettle and the staged parallel sample kettle to achieve pressure equilibrium, respectively; V R is the volume of the constant volume piston reference kettle, cm 3 ; V f is the total residual free volume in the staged parallel sample reactor; the Gibbs adsorption capacity of the entire adsorption experiment GSE n The formula is as follows: n is the total number of pressure values ​​required for the experiment, GSE n represents the sum of ΔGBE under n test conditions; ΔGBE iis the adsorption capacity of the i-th test pressure value; if it is a multi-component gas, the absolute adsorption capacity of each component is calculated as follows: V ab,i =GBE n,i +GBE n ×ρ free / (ρ ad × i ) where V ab,i is the absolute adsorption amount of component i, mol; GBE n,i is the Gibbs adsorption capacity of component i, mol; GBE n is the total Gibbs adsorption capacity, mol; ρ free ,ρ ad are the free phase and adsorbed phase densities, g / cm 3 ;x i is the molar concentration of component i, mol / L;

[0030] Step 8: Select a specific pressure value for sample structure analysis. After the system reaches equilibrium, close the No. 1 secondary automatic high-pressure connecting needle valve to saturate the No. 1 sample kettle with a specific pressure environment for 24 hours. Then, use a gas chromatograph to analyze the components of the gas in the No. 1 sample kettle. Disassemble and remove the sample in the No. 1 sample kettle for chemical and physical structure analysis.

[0031] Step 9: If a specific pressure value is set, after the specific adsorption pressure value experiment is completed, repeat step 5 and use the calculation formula: Where V f1 is the remaining free volume in the No. 1 sample kettle, and the other physical parameters are consistent with the calculation formula in step 5;

[0032] Step 10. If it is necessary to perform structural analysis on samples at multiple specific pressure values, repeat step 8. After the final adsorption pressure value experiment is completed, open the vent valve and the six-way regulating valve of the constant volume piston reference kettle, connect the exhaust gas treatment chamber, vent the gas in the constant volume piston reference kettle, open the first and second level automatic high pressure connecting needle valves of the sample kettle, and inject the high pressure gas in the inner cavity of the sample kettle into the constant volume piston reference kettle until the pressure value in the inner cavity of the sample kettle reaches the target value. Then, close the first and second level automatic high pressure connecting needle valves of the sample kettle and wait for desorption equilibrium. During this process, the temperature and pressure data acquisition and processing system collects the gas pressure and temperature in the inner cavity of the constant volume piston reference kettle and the sample kettle. When the system pressure fluctuation range is less than 0.1psi / h and the temperature fluctuation range is less than 0.025℃ / h, the desorption experiment under the desorption pressure is considered to be completed.

[0033] Step 11: Repeat step 9 and gradually reduce the pressure by 1 MPa to carry out the next desorption pressure test until all desorption pressure tests are completed.

[0034] Beneficial effects of the present invention:

[0035] (1) The present invention utilizes multiple groups of 50mL fixed-volume small-volume experimental devices in parallel to realize the stage-by-stage structural analysis of the adsorption experiment between the adsorbed gas (adsorbate) and the adsorbent material (adsorbent) during a series of high-pressure adsorption experiments, and can more accurately carry out the adsorption amount of the high-pressure adsorbate and the adsorbent during the multi-pressure point adsorption experiment and the adsorbent structure changes at the stage-by-stage specific pressure value. The experimental device has a simple structure, is easy to operate, has a good use effect, and is easy to promote.

[0036] (2) The staged parallel high-pressure gas adsorption / desorption device provided by the present invention has a simple structure, safe experimental operation, unmanned data recording and curve drawing, and high accuracy and reliability of experimental results; by analyzing the specific pressure value or staged material structure during the whole adsorption process through six groups of staged parallel high-pressure gas sample kettles, it is possible to more accurately carry out the adsorption amount of high-pressure adsorbent and adsorbent during the multi-pressure point adsorption experiment and the adsorbent structure change of the staged specific pressure value. The present invention designs a staged parallel high-pressure constant volume small volume sample kettle by modifying the structure of the traditional isothermal adsorption sample kettle. During the experiment, helium and a two-stage automatic high-pressure connecting needle valve are used to perform multi-stage residual free volume determination, so as to realize the calibration and closure of the volume of each parallel sample kettle after sample loading, thereby avoiding affecting the entire adsorption experiment process; the present invention more accurately analyzes the material structure under a specific pressure during the high-pressure gas adsorption process, which can solve the problem that the current experimental technology and equipment cannot change the structural characteristics of the staged specific points during the whole adsorption process, and provides a clear solution idea;

[0037] (3) The experimental scheme of the present invention proposes a new measurement method for high-temperature and high-pressure gas isothermal adsorption experiments, which can effectively avoid experimental errors caused by experimental sample replacement and device installation, and improve the accuracy and reliability of experimental data; through real-time monitoring and control system to automatically collect data and draw curves, it can effectively reduce the experimental errors of human measurement results; through the experimental gas safety alarm system and waste treatment system, it can effectively ensure the safety, efficiency, low carbon and environmental protection of the entire experimental process; it can determine the influence of high-temperature and high-pressure gas at a specific pressure on the adsorptive reservoir structure during the entire adsorption process, thereby providing guidance for the economy and safety of deep sealed storage formations. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 It is a schematic diagram of the structure of a staged parallel high-pressure sample kettle;

[0039] Figure 2 This is a schematic diagram of the overall distribution of a small volume sample in a sample kettle (top view);

[0040] Figure 3It is a schematic diagram of the overall structure of a stage-type parallel high-pressure gas constant-pressure adsorption / desorption test device;

[0041] In the figure, 1. gas cylinder; 2. pneumatic valve; 3. one-way ball valve; 4. automatic high-pressure needle valve; 5. filter; 6. gas booster pump; 7. thermostat; 8. thermostat temperature adjustment knob; 9. thermostat control panel; 10. external temperature sensor of kettle; 11. gas distribution prefabricated kettle; 12. fine adjustment valve; 13. pressure sensor; 14. constant volume piston reference kettle; 15. temperature and pressure data acquisition and processing system; 16. computer; 17. first-level automatic high-pressure connecting needle valve; 18. vacuum valve; 19. six-way regulating valve; 20. vacuum gauge; 21. Dryer; 22. Vacuum pump; 23. Waste gas treatment chamber; 24. Reference kettle temperature and pressure sensor; 25. Sample kettle temperature and pressure sensor; 26. Experimental gas safety alarm module; 27. Experimental gas concentration probe; 28. Constant volume piston reference kettle vent valve; 29. ​​Staged parallel sample kettle; 30. Small volume sample inner kettle; 31. Secondary automatic high pressure connecting needle valve; 32. 1mL piston buffer tube; 33. Safety valve; 34. Gas sensitive electrode; 35. Gas chromatograph; 36. Precision small range liquid injection pump; 37. Multi-group gas distribution control module. DETAILED DESCRIPTION

[0042] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] The purpose of the present invention is to provide a staged parallel high-pressure gas adsorption / desorption test device and method to realize the staged dynamic analysis of the impact on the reservoir structure during the high-pressure gas storage process under deep conditions. The experimental device uses six groups of 50mL fixed-volume small-volume experimental devices in parallel to realize the staged structural analysis of the adsorption experiment between the adsorbed gas (adsorbate) and the adsorbent material (adsorbent) during a series of high-pressure adsorption experiments. It can more accurately carry out the adsorption amount and stage-specific pressure value of the adsorbent structure changes of the high-pressure adsorbate and the adsorbent during the multi-pressure point adsorption experiment, providing a technical reference for deep gas storage, etc.

[0044] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0045] The present invention provides a staged parallel high-pressure gas constant-pressure adsorption / desorption test device. By connecting multiple groups of 50mL fixed-volume small-volume sample kettles in parallel, the staged structural analysis of the adsorption experiment between the adsorbed gas (adsorbate) and the adsorbent material (reservoir structure material) is realized during the high-pressure adsorption experiment. In addition, a variety of structural characterization methods are combined to more accurately explore the adsorption amount of the high-pressure adsorbate and the adsorbent during the multi-pressure point adsorption experiment and the adsorbent structure changes of the staged specific pressure values.

[0046] The staged parallel high-pressure gas constant-pressure adsorption / desorption device provided by the present invention is as follows Figures 1 to 3 As shown, it specifically includes: gas supply system, gas distribution prefabricated kettle, constant volume piston reference kettle, staged parallel sample kettle, vacuum system, waste gas buffer system, experimental gas safety monitoring and alarm system, terminal operation and real-time data monitoring system;

[0047] A gas supply system, the gas supply system is used to supply gas to the entire adsorption / desorption device;

[0048] A gas distribution prefabricated kettle 11, a constant volume piston reference kettle 14, and a staged parallel sample kettle 29 are arranged in a constant temperature box; the gas distribution prefabricated kettle 11, the constant volume piston reference kettle 14, and the staged parallel sample kettle 29 are connected to each other at the top through pipelines; the gas distribution prefabricated kettle is connected to the gas supply system; the staged parallel sample kettle 29 includes a cylindrical outer kettle and six groups of constant volume small volume sample inner kettles 30 evenly arranged in the kettle, and the tops of the small volume sample inner kettles are respectively provided with 1mL piston buffer tubes 32, and the mass of the sample to be tested is placed in the small volume sample inner kettle, and the sample kettle temperature and pressure sensor 25 is arranged on the top of the cylindrical outer kettle of the sample kettle, and the top of the sample kettle outer kettle is equipped with a safety valve 33 and a first-level automatic high-pressure connecting needle valve 17;

[0049] The thermostat 7 is provided with a thermostat temperature adjustment knob 8, which is used to adjust the temperature in the thermostat 7;

[0050] Furthermore, a fine-tuning valve 12 and a filter 5 are provided on the connecting pipeline between the gas distribution prefabricated kettle 11 and the constant volume piston reference kettle 14; on the pipeline connecting the gas distribution prefabricated kettle 11 and the stage-type parallel sample kettle 29, a pressure sensor 13 is connected to the top of the kettle body of the gas distribution prefabricated kettle 11, and a sample kettle temperature and pressure sensor 25 is connected to the top of the outer kettle of the stage-type parallel sample kettle; a first-level automatic high-pressure connecting needle valve 17 is provided on the connecting pipeline between the constant volume piston reference kettle and the outer kettle of the stage-type parallel sample kettle; a reference kettle temperature and pressure sensor 24 is connected to the top of the constant volume piston reference kettle 14;

[0051] Six groups of high-pressure gas sample inner kettles with the same volume (50 mL) are arranged inside the staged parallel sample kettle, that is, six groups of small-volume sample inner kettles 30, such as Figure 2 As shown, the small volume sample inner kettle 30 is made of high temperature and high pressure resistant 316L stainless steel, used to place test samples, with a pressure resistance of 60MPa, and equipped with a safety valve 33. When the pressure is higher than the maximum pressure that the parallel 50mL fixed volume small volume sample inner kettle 30 can withstand, the safety valve 33 will automatically open to release the pressure to prevent the pressure from being too high and causing danger. Each small volume sample inner kettle is equipped with a secondary automatic high pressure connecting needle valve 31 on the top. After closing the corresponding secondary automatic high pressure connecting needle valve, the required small volume sample inner kettle can be disassembled for structural analysis without affecting the overall adsorption experiment. The gas supply system, the gas distribution prefabricated kettle 11, the fixed volume piston reference kettle 14, the primary automatic high pressure connecting needle valve 17 and the parallel 50mL fixed volume small volume sample inner kettle 30 are connected in sequence through pipelines; as shown in FIG. Figure 2 As shown, the six small-volume samples are evenly spaced.

[0052] The terminal operation and real-time data monitoring system includes a temperature and pressure data acquisition and processing system 15 and a computer 16. The temperature and pressure data acquisition and processing system 15 sends data to the computer 16 in real time through a data transmission line. The computer is used to record the pressure and temperature data values ​​and draw change curves respectively; the temperature and pressure data acquisition and processing system includes a data transmission line and a signal converter; the pressure sensor of the gas distribution prefabrication kettle, the sample kettle temperature and pressure sensor, and the reference kettle temperature and pressure sensor are all connected to the signal converter of the temperature and pressure data acquisition and processing system through the data transmission line; the specific control process is: the above-mentioned pressure sensor, sample kettle temperature and pressure sensor, and reference kettle temperature and pressure sensor are connected to the signal converter through the data transmission line, and the signal converter transmits the data to the temperature and pressure monitoring interface of the computer, and draws the curve according to the temperature and pressure values;

[0053] The pressure sensor 13 of the gas prefabrication kettle, the temperature and pressure sensor 25 of the sample kettle, and the temperature and pressure sensor 24 of the reference kettle are all connected to the signal converter of the temperature and pressure data acquisition and processing system through a high-precision data transmission line; the specific control process is: the pressure sensor 13, the temperature and pressure sensor 25 of the sample kettle, and the temperature and pressure sensor 24 of the reference kettle are connected to the RS485 signal converter through the data transmission line, and the signal converter transmits the data to the temperature and pressure monitoring interface of the computer, and draws a curve according to the temperature and pressure values;

[0054] The temperature and pressure sensors on the gas distribution prefabrication kettle, the constant volume piston reference kettle and the staged parallel sample kettle are all electrically connected to the temperature and pressure data acquisition and processing system 15 .

[0055] The experimental gas safety monitoring and alarm system is electrically connected to the computer. The system includes an experimental gas safety alarm module 26 and an experimental gas concentration probe 27 (set at the upper, middle and lower positions of the side wall of the constant temperature box, with a total of three groups). The experimental gas concentration probe is used to measure the experimental gas concentration in the constant temperature box, and the experimental gas safety alarm module is used to alarm when the experimental gas concentration measured by the experimental gas concentration probe is higher than the set safety value. The probe adopts a two-wire pluggable connection, and the type of probe can be selected according to the experimental requirements. In this way, the concentration of the experimental gas inside the equipment environment is measured by the experimental gas concentration probe 27. When the concentration is higher than the set safety value, an alarm is triggered and the temperature control system is connected to increase the fan power for gas discharge. Furthermore, the experimental gas safety alarm module selected in this embodiment is GTYQ-A-4000, which records the changes in the system gas concentration in real time through the module digital display screen, and sets the alarm module gas concentration safety value and dangerous concentration critical time to 30s. It is used to alarm when the experimental gas concentration measured by the experimental gas concentration probe is higher than the set safety value and lasts for more than 30s, and is connected to the constant temperature box temperature control system through electrical signals to increase the fan power for gas discharge.

[0056] A preferred embodiment is provided, in which the gas supply system includes a gas cylinder 1, a pneumatic valve 2, a one-way ball valve 3, an automatic high-pressure needle valve 4 and a filter 5 which are connected in sequence. The outlet end of the filter 5 is connected to a gas booster pump 6 for boosting the gas to meet the pressure of the high-pressure gas required for the experiment, and the maximum outlet pressure is 70MPa / 10150psi. The gas booster pump 6 is connected to a multi-group gas distribution control module 37 for producing multi-component gas. Several gas cylinders 1 are provided, which are used to store helium and different types of experimental gases respectively; the experimental gas can be set according to the specific use environment and experimental requirements, such as methane, carbon dioxide, etc. In this embodiment, carbon dioxide is taken as an example.

[0057] A preferred embodiment is provided, in which the parallel 50mL fixed-volume small-volume sample inner kettle and the two-stage automatic high-pressure connecting needle valve of the stage-type parallel high-pressure gas adsorption / desorption test device can be opened, closed and disassembled according to the specific pressure requirements of the experiment, which greatly expands the applicability of the equipment adsorption / desorption experiment to material structure analysis; with such a setting, six groups of parallel high-pressure gas sample kettles can realize the material structure characterization and analysis at the specific pressure value required by the experiment during the whole adsorption process; the adsorption characteristics and structural evolution during the pretreatment of adsorbent materials can be determined.

[0058] A preferred embodiment is provided, in which the vacuum system and the waste gas buffer system are respectively connected to the two passages of the six-way regulating valve, and do not interfere with each other. The gas distribution prefabrication kettle, the constant volume piston reference kettle and the stage-type parallel sample kettle are connected to the vacuum system through a pipeline, and a vacuum valve 18 and a six-way regulating valve 19 are provided on the pipeline. The vacuum system includes a vacuum gauge 20, a dryer 21 and a vacuum pump 22; the waste gas buffer system includes a waste gas treatment chamber 23; by controlling the vacuum valve 18, the vacuum environment of the gas distribution prefabrication kettle 11, the constant volume piston reference kettle 14, and the stage-type parallel sample kettle 29 is realized. The vacuum gauge 20, the dryer 21 and the vacuum pump 22 are connected in sequence to one passage of the six-way regulating valve 19, and the waste gas treatment chamber 23 is connected to the other passage.

[0059] With such arrangement, the vacuum pump 22 is used to extract the gas inside the experimental device to ensure that the experiment is not interfered by other external gases; the dryer 21 is used to prevent water in the instrument from entering the vacuum pump 22 when the vacuum pump 22 is working, causing damage to the vacuum pump 22.

[0060] A preferred embodiment is provided, in which the No. 1 secondary automatic high-pressure connecting needle valve and the No. 2 secondary high-pressure connecting needle valve in the 50mL fixed-volume small-volume sample inner kettle 30 are connected in parallel, and the pressure parameters are set by the computer 16 to realize the sealing and disassembly of the sample kettle at a specific pressure value at a stage without affecting the overall adsorption experiment conditions, and the structural analysis of the material under a specific pressure value. The reference kettle temperature and pressure sensor 24 and the sample kettle temperature and pressure sensor 25 are both Swiss Keller temperature and pressure sensors, which are used to obtain the temperature and pressure values ​​in the kettle in real time; in this embodiment, the pressure accuracy of the reference kettle temperature and pressure sensor 24 and the sample kettle temperature and pressure sensor 25 is 0.01% F·S, the range is 0-1000 bar, and the temperature accuracy is 0.1% F·S, the range is 10-80°C.

[0061] In this way, the real-time data obtained by the reference kettle temperature and pressure sensor 24, the sample kettle temperature and pressure sensor 25 and the pressure sensor 13 are transmitted to the temperature and pressure data acquisition and processing system 15 and the computer 16. The software runs in the Windows environment, and the instrument working status is displayed on the interface of the computer 16. After the operator sets the recording parameters, unattended operation can be achieved. The computer 16 page system can automatically collect all pressures and temperatures, and draw real-time change curves. After processing, high-pressure gas adsorption / desorption original data reports, analysis reports and isothermal adsorption curves can be generated, and database access and excel format files are generated at the same time for users to save and view.

[0062] A preferred embodiment is provided, in which a gas-sensitive electrode 34 is provided on each small-volume sample inner kettle in the constant-volume piston reference kettle 14 and the staged parallel sample kettle 29, and two sets of internal and external connecting joints are provided on the side wall of the staged parallel sample kettle 29, and the connecting pipes corresponding to the internal and external structures are respectively connected to the gas chromatograph 35 and the precise small-scale liquid injection pump 36; a 1mL piston buffer tube 32 is provided on the connecting pipe between the precise small-scale liquid injection pump 36 and the small-volume sample inner kettle, and the original manual sampling device is modified to: liquid is injected through the precise small-scale liquid injection pump 36, and the piston is pushed to directly enter the gas chromatograph 35 for adsorbate gas detection in the experimental sample. The gas-sensitive electrode is a replaceable electrode material, and the corresponding electrode can be selected according to different test gases.

[0063] The present invention provides a staged parallel high-pressure gas constant-pressure adsorption / desorption test method, using the staged parallel high-pressure gas constant-pressure adsorption / desorption test device, the test method comprises the following steps:

[0064] Step 1: Prepare single-component or multi-component experimental gas: Before conducting the adsorption test, first prepare the required concentration and component adsorbent gas through the gas preparation supply system and the gas preparation kettle. Based on the real gas state equation, the required gas preparation ratio is achieved by controlling the gas pressure. For multi-component gases, the gas preparation sequence is based on the molar concentration from small to large. The whole process needs to maintain constant temperature. The calculation equation is as follows: PV = Z 混合气 n 总 RT, where P is the gas pressure, MPa; V is the volume of the gas prefabricated kettle, cm 3 ; Z is the compressibility factor of the mixed gas; n is the total amount of substance in the mixed gas, mol; R is the gas universal constant, 8.314 J / (mol·K); T is the experimental environment temperature, K; n i =a i ×n 总 Where n i is the amount of substance of component i of the mixed gas, mol; a i is the molar concentration of component i, %; n 总 is the total amount of substance in the mixer, mol;

[0065] After step one, perform an airtightness check. The specific operating steps are as follows: fill the gas adsorption system with helium, stabilize the pressure at 1.5 MPa higher than the maximum experimental pressure required for the isothermal adsorption experiment and maintain it for more than 24 hours, adjust the temperature of the thermostat to the reservoir temperature, and continuously observe the computer system page curve. If the pressure indication changes less than 0.1 psi / h and the temperature indication changes less than 0.025°C / h, proceed to step two.

[0066] Step 2: Sample pretreatment: Before conducting the isothermal adsorption experiment, the experimental samples are first divided into six groups for particle size screening and weighing, and then the samples to be tested are subjected to balanced water treatment or drying treatment according to the experimental requirements. The samples are placed in a vacuum blower at 105°C and dried for 12 hours. After weighing again, the six groups of samples of equal mass are placed in six groups of small volume sample inner kettles;

[0067] Step 3, calibrate the volume of the constant volume piston reference kettle; evacuate the entire experimental system, place the piston plate of the inner cavity of the constant volume piston reference kettle at the bottom, fill the constant volume piston reference kettle with high pressure helium, and record the equilibrium pressure and temperature in the kettle after reaching equilibrium; open the second automatic high pressure connecting needle valve to inject helium into the staged parallel sample kettle, and record the equilibrium pressure and temperature after the constant volume piston reference kettle and the staged parallel sample kettle are both adsorbed and balanced, calculate the full scale of the constant volume piston reference kettle and the total volume of the staged parallel sample kettle cavity, and according to the law of conservation of mass and the ideal gas state equation PV = nZRT, the calculation formula is as follows: Where P R is the initial equilibrium pressure in the constant volume piston reference kettle, MPa; M He is the relative molecular mass of helium, g / mol; Z R is the initial equilibrium pressure P in the constant volume piston reference kettle R Helium compression factor under R is the volume of the constant volume piston reference kettle, cm 3 ;P S V is the equilibrium pressure after the constant volume piston reference kettle and the staged parallel sample kettle are connected, MPa; S is the total volume of the six sample kettles in parallel in a staged manner, cm 3 ; Z S It is the equilibrium pressure P after the constant volume piston reference kettle and the stage type parallel sample kettle are connected. S The helium compression factor under ; R is the gas universal constant, 8.314 J / (mol·K); T is the experimental environment temperature, K;

[0068] Place a standard block with a volume of V0 in the sample kettle and repeat the helium volume calibration operation. According to the law of mass conservation, the calculation formula is as follows: Combine the volume calibration equations before and after the standard block is placed to obtain the full-scale volume of the constant-volume piston reference kettle;

[0069] Step 4, determination of the total residual free volume of the staged parallel sample kettles; evacuate the entire device, fill the constant volume piston reference kettle with helium, stop gas injection after adsorption equilibrium, and record the equilibrium pressure and temperature in the constant volume piston reference kettle; then open the first-level automatic high-pressure connecting needle valve and all the second-level automatic high-pressure connecting needle valves to inject gas into the kettles of the six groups of sample kettles, record the equilibrium pressure and temperature after the constant volume piston reference kettle and the sample kettle are both adsorbed and balanced, calculate the total residual free volume in the sample kettle, and according to the law of conservation of mass and the ideal gas state equation PV = nZRT, the calculation formula is as follows: Where P R is the initial equilibrium pressure in the constant volume piston reference kettle, MPa; M He is the relative molecular mass of helium, g / mol; Z R is the initial equilibrium pressure P in the constant volume piston reference kettle R Helium compression factor under R is the volume of the constant volume piston reference kettle, cm 3 ;P S V is the equilibrium pressure after the constant volume piston reference kettle and the sample kettle are connected, MPa; fTotal is the total volume of the six sample kettles, cm 3 ; Z S It is the equilibrium pressure P after the constant volume piston reference kettle and the sample kettle are connected S The helium compression factor under ; R is the gas universal constant, 8.314 J / (mol·K); T is the experimental environment temperature, K;

[0070] Step 5. Determine the remaining free volume of each of the six parallel sample kettles; by closing the No. 1, 2, 3, 4, and 5 secondary automatic high-pressure connecting needle valves in sequence, repeat step 2 for five times to determine the helium volume. The calculation formula is as follows: V f The value decreases with the gradual closing of the secondary automatic high-pressure connecting needle valves No. 1, 2, 3, 4, and 5; i is the number of six sets of parallel sample kettles that need to be disassembled, pieces; V fi is the remaining free volume of the i-th constant volume small volume sample inner kettle, cm 3 ; V f is the total remaining free volume in the sample kettle after disassembly, cm 3 ; n represents the number of kettles in the disassembled small volume sample, V fTofal Represents the total volume of the kettle in six groups of small volume samples, cm 3 ;

[0071] Step 6, high-pressure gas isothermal adsorption experiment; evacuate the gas distribution prefabricated kettle, the constant volume, constant pressure, constant volume piston reference kettle and the staged parallel sample kettle for 1 hour, close all valves, and set the experimental target temperature through the thermostat temperature control system; inject high-pressure gas into the gas distribution prefabricated kettle, and observe the temperature and pressure values; when the pressure fluctuation range is less than 0.1psi / h and the temperature fluctuation range is less than 0.025℃ / h, the state value is used as the standard value for measuring equilibrium, open the fine-tuning valve, inject gas into the constant volume piston reference kettle, record the equilibrium pressure and temperature of the constant volume piston reference kettle, and when the pressure and temperature reach equilibrium, open one The first and second level automatic high-pressure connecting needle valves and the liquid automatic high-pressure connecting valve push the piston plate to change the volume of the lower chamber of the constant-volume piston reference kettle according to the set pressure value through the precision double-cylinder injection pump, and inject the gas in the upper chamber of the constant-volume piston reference kettle into the six sets of parallel sample kettles at the same time. When the pressure in the sample kettle reaches the set value, the first level automatic high-pressure connecting needle valve is closed to wait for adsorption equilibrium. In this process, the temperature and pressure data acquisition and processing system collects the gas pressure and temperature in the constant-volume piston reference kettle and the sample kettle. When the system pressure fluctuation range and temperature fluctuation range reach the equilibrium standard, it is considered that the adsorption experiment under the adsorption pressure is completed.

[0072] Step 7. After the last pressure adsorption experiment is completed, open the first-level automatic high-pressure connecting needle valve and the liquid automatic high-pressure connecting valve between the constant volume piston reference kettle and the sample kettle again, and gradually increase the pressure by 1MPa to carry out the next adsorption pressure experiment until all adsorption pressure experiments are completed. According to the law of conservation of mass, the formula for calculating the adsorption amount of the adsorption process of one experimental pressure value is as follows: Wherein, m is the mass of the sample to be tested in the experiment, g; R is the universal gas constant, 8.314 J / (mol·K); T is the experimental environment temperature, K; P1 and P2 are the initial equilibrium pressures of the constant volume piston reference kettle and the staged parallel sample kettle, MPa; P3 and P4 are the equilibrium pressures of the constant volume piston reference kettle and the staged parallel sample kettle with the connecting valve opened to achieve pressure equilibrium, MPa; Z1 and Z2 are the gas compression factors at the initial equilibrium pressures P1 and P2 of the constant volume piston reference kettle and the staged parallel sample kettle, respectively; Z3 and Z4 are the gas compression factors at the equilibrium pressures P3 and P4 of the constant volume piston reference kettle and the staged parallel sample kettle to achieve pressure equilibrium, respectively; V R is the volume of the constant volume piston reference kettle, cm 3 ; V f is the total residual free volume in the staged parallel sample reactor; the Gibbs adsorption capacity of the entire adsorption experiment GSE n The formula is as follows: n is the total number of pressure values ​​required for the experiment, GSE n represents the sum of ΔGBE under n test conditions; ΔGBE iis the adsorption capacity of the i-th test pressure value; if it is a multi-component gas, the absolute adsorption capacity of each component is calculated as follows: V ab,i =GBE n,i +GBE n ×ρ free / (ρ ad × i ) where V ab,i is the absolute adsorption amount of component i, mol; GBE n,i is the Gibbs adsorption capacity of component i, mol; GBE n is the total Gibbs adsorption capacity, mol; ρ free ,ρ ad are the free phase and adsorbed phase densities, g / cm 3 ;x i is the molar concentration of component i, mol / L;

[0073] Step 8: Select a specific pressure value for sample structure analysis. After the system reaches equilibrium, close the No. 1 secondary automatic high-pressure connecting needle valve to saturate the No. 1 sample kettle with a specific pressure environment for 24 hours. Then, use a gas chromatograph to analyze the components of the gas in the No. 1 sample kettle. Disassemble and remove the sample in the No. 1 sample kettle for chemical and physical structure analysis.

[0074] Step 9: If a specific pressure value is set, after the specific adsorption pressure value experiment is completed, repeat step 5 and use the calculation formula: Where V f1 is the remaining free volume in the No. 1 sample kettle, and the other physical parameters are consistent with the calculation formula in step 5;

[0075] Step 10. If it is necessary to perform structural analysis on samples at multiple specific pressure values, repeat step 8. After the final adsorption pressure value experiment is completed, open the vent valve and the six-way regulating valve of the constant volume piston reference kettle, connect the exhaust gas treatment chamber, vent the gas in the constant volume piston reference kettle, open the first and second level automatic high pressure connecting needle valves of the sample kettle, and inject the high pressure gas in the inner cavity of the sample kettle into the constant volume piston reference kettle until the pressure value in the inner cavity of the sample kettle reaches the target value. Then, close the first and second level automatic high pressure connecting needle valves of the sample kettle and wait for desorption equilibrium. During this process, the temperature and pressure data acquisition and processing system collects the gas pressure and temperature in the inner cavity of the constant volume piston reference kettle and the sample kettle. When the system pressure fluctuation range is less than 0.1psi / h and the temperature fluctuation range is less than 0.025℃ / h, the desorption experiment under the desorption pressure is considered to be completed.

[0076] Step 11: Repeat step 9 and gradually reduce the pressure by 1 MPa to carry out the next desorption pressure test until all desorption pressure tests are completed.

[0077] It should be noted that it is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive, and the scope of the present invention is defined by the claims rather than the above description, so it is intended to include all changes within the meaning and scope of the equivalent elements of the claims, and any figure mark in the claims should not be regarded as limiting the claims involved.

[0078] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A staged parallel high-pressure gas constant-pressure adsorption / desorption test method, characterized in that: It is used to simulate the correspondence analysis between the adsorption amount and the structure of the experimental material under a specific pressure value during the whole process of constant pressure adsorption / desorption of a single component or multi-component gas under high temperature and high pressure conditions in deep reservoirs. The device can be disassembled to characterize and analyze the structure of the experimental material without affecting the overall experimental conditions of the whole process. The test method adopts a staged parallel high-pressure gas constant-pressure adsorption / desorption test device for testing, and the test device includes a gas preparation and supply system, a gas preparation kettle, a constant-volume piston reference kettle, a staged parallel sample kettle, a vacuum system, an exhaust gas buffer system, an experimental gas safety monitoring and alarm system, and a terminal operation and real-time data monitoring system; the tops of the gas preparation kettle, the constant-volume piston reference kettle and the staged parallel sample kettle are connected by pipelines; the gas preparation kettle is connected to the gas preparation and supply system, and a 1mL piston buffer is provided at the bottom The tube is connected to the gas chromatograph; the bottom of the constant volume piston reference kettle is connected to a liquid pressure gauge, a liquid storage tank and a precision double-cylinder injection pump; the staged parallel sample kettle comprises a cylindrical outer kettle and six groups of constant volume small volume sample inner kettles evenly arranged in the kettle, and the mass of the sample to be tested is placed in the small volume sample inner kettle, and the sample kettle temperature and pressure sensor is arranged on the top of the cylindrical outer kettle of the staged parallel sample kettle, and the top of the outer kettle of the staged parallel sample kettle is equipped with a safety valve and a first-level automatic high-pressure connecting needle valve; a second-level automatic high-pressure connecting needle valve is arranged on the top of each small volume sample inner kettle; The test method comprises the following steps: Step 1: Prepare single-component or multi-component experimental gas: Before conducting the adsorption test, first prepare the required concentration and component adsorbent gas through the gas preparation supply system and the gas preparation kettle. Based on the real gas state equation, the required gas preparation ratio is achieved by controlling the gas pressure. For multi-component gases, the gas preparation sequence is based on the molar concentration from small to large. The whole process needs to maintain constant temperature. The calculation equation is as follows: PV = Z 混合气 n 总 RT, where P is the gas pressure, MPa; V is the volume of the gas prefabricated kettle, cm 3 ; Z is the compressibility factor of the mixed gas; n is the total amount of substance in the mixed gas, mol; R is the gas universal constant, 8.314 J / (mol·K); T is the experimental environment temperature, K; n i =a i ×n 总 Where n i is the amount of substance of component i of the mixed gas, mol; a i is the molar concentration of component i, %; n 总 is the total amount of substance in the mixer, mol; Step 2: Sample pretreatment: Before conducting the isothermal adsorption experiment, the experimental samples are first divided into six groups for particle size screening and weighing, and then the samples to be tested are subjected to balanced water treatment or drying treatment according to the experimental requirements. The samples are placed in a vacuum blower at 105°C and dried for 12 hours. After weighing again, the six groups of samples of equal mass are placed in six groups of small volume sample inner kettles; Step 3, calibrate the volume of the constant volume piston reference kettle; evacuate the entire experimental system, place the piston plate of the inner cavity of the constant volume piston reference kettle at the bottom, fill the constant volume piston reference kettle with high pressure helium, and record the equilibrium pressure and temperature in the kettle after reaching equilibrium; open the second automatic high pressure connecting needle valve to inject helium into the staged parallel sample kettle, and record the equilibrium pressure and temperature after the constant volume piston reference kettle and the staged parallel sample kettle are both adsorbed and balanced, calculate the full scale of the constant volume piston reference kettle and the total volume of the staged parallel sample kettle cavity, and according to the law of conservation of mass and the ideal gas state equation PV = nZRT, the calculation formula is as follows: Where P R is the initial equilibrium pressure in the constant volume piston reference kettle, MPa; M He is the relative molecular mass of helium, g / mol; Z R is the initial equilibrium pressure P in the constant volume piston reference kettle R Helium compression factor under R is the volume of the constant volume piston reference kettle, cm 3 ;P S V is the equilibrium pressure after the constant volume piston reference kettle and the staged parallel sample kettle are connected, MPa; S is the total volume of the six sample kettles in parallel in a staged manner, cm 3 ; Z S It is the equilibrium pressure P after the constant volume piston reference kettle and the stage type parallel sample kettle are connected. S The helium compression factor under ; R is the gas universal constant, 8.314 J / (mol·K); T is the experimental environment temperature, K; Place a standard block with a volume of V0 in the sample kettle and repeat the helium volume calibration operation. According to the law of mass conservation, the calculation formula is as follows: Combine the volume calibration equations before and after the standard block is placed to obtain the full-scale volume of the constant-volume piston reference kettle; Step 4, determination of the total residual free volume of the staged parallel sample kettles; evacuate the entire device, fill the constant volume piston reference kettle with helium, stop gas injection after adsorption equilibrium, and record the equilibrium pressure and temperature in the constant volume piston reference kettle; then open the first-level automatic high-pressure connecting needle valve and all the second-level automatic high-pressure connecting needle valves to inject gas into the kettles of the six groups of sample kettles, record the equilibrium pressure and temperature after the constant volume piston reference kettle and the sample kettle are both adsorbed and balanced, calculate the total residual free volume in the sample kettle, and according to the law of conservation of mass and the ideal gas state equation PV = nZRT, the calculation formula is as follows: Where P R is the initial equilibrium pressure in the constant volume piston reference kettle, MPa; M He is the relative molecular mass of helium, g / mol; Z R is the initial equilibrium pressure P in the constant volume piston reference kettle R Helium compression factor under R is the volume of the constant volume piston reference kettle, cm 3 ;P S V is the equilibrium pressure after the constant volume piston reference kettle and the sample kettle are connected, MPa; fTotal is the total volume of the six sample kettles, cm 3 ; Z S It is the equilibrium pressure P after the constant volume piston reference kettle and the sample kettle are connected S The helium compression factor under ; R is the gas universal constant, 8.314 J / (mol·K); T is the experimental environment temperature, K; Step 5. Determine the remaining free volume of each of the six parallel sample kettles; by closing the No. 1, 2, 3, 4, and 5 secondary automatic high-pressure connecting needle valves in sequence, repeat step 2 for five times to determine the helium volume. The calculation formula is as follows: V f The value decreases with the gradual closing of the secondary automatic high-pressure connecting needle valves No. 1, 2, 3, 4, and 5; i is the number of six sets of parallel sample kettles that need to be disassembled, pieces; V fi is the remaining free volume of the i-th constant volume small volume sample inner kettle, cm 3 ; V f is the total remaining free volume in the sample kettle after disassembly, cm 3 ; n represents the number of kettles in the disassembled small volume sample, V fTofal Represents the total volume of the kettle in six groups of small volume samples, cm 3 ; Step 6, high-pressure gas isothermal adsorption experiment; evacuate the gas distribution prefabricated kettle, the constant volume piston reference kettle and the stage-type parallel sample kettle for 1 hour, close all valves, and set the experimental target temperature through the thermostat temperature control system; inject high-pressure gas into the gas distribution prefabricated kettle, and observe the temperature and pressure values; when the pressure fluctuation range is less than 0.1psi / h and the temperature fluctuation range is less than 0.025℃ / h, the state value is used as the standard value for measuring the equilibrium, open the fine-tuning valve, inject gas into the constant volume piston reference kettle, record the equilibrium pressure and temperature of the constant volume piston reference kettle, and when the pressure and temperature reach equilibrium, open the first and The secondary automatic high-pressure connecting needle valve and the liquid automatic high-pressure connecting valve push the piston plate to change the volume of the lower chamber of the constant-volume piston reference kettle according to the set pressure value through the precision double-cylinder injection pump, and inject the gas in the upper chamber of the constant-volume piston reference kettle into the six sets of parallel sample kettles at the same time. When the pressure in the sample kettle reaches the set value, the primary automatic high-pressure connecting needle valve is closed to wait for adsorption equilibrium. In this process, the temperature and pressure data acquisition and processing system collects the gas pressure and temperature in the constant-volume piston reference kettle and the sample kettle. When the system pressure fluctuation range and temperature fluctuation range reach the equilibrium standard, it is considered that the adsorption experiment under the adsorption pressure is completed. Step 7. After the last pressure adsorption experiment is completed, open the first-level automatic high-pressure connecting needle valve and the liquid automatic high-pressure connecting valve between the constant volume piston reference kettle and the sample kettle again, and gradually increase the pressure by 1MPa to carry out the next adsorption pressure experiment until all adsorption pressure experiments are completed. According to the law of conservation of mass, the formula for calculating the adsorption amount of the adsorption process of one experimental pressure value is as follows: Wherein, m is the mass of the sample to be tested in the experiment, g; R is the universal gas constant, 8.314 J / (mol·K); T is the experimental environment temperature, K; P1 and P2 are the initial equilibrium pressures of the constant volume piston reference kettle and the staged parallel sample kettle, MPa; P3 and P4 are the equilibrium pressures of the constant volume piston reference kettle and the staged parallel sample kettle with the connecting valve opened to achieve pressure equilibrium, MPa; Z1 and Z2 are the gas compression factors at the initial equilibrium pressures P1 and P2 of the constant volume piston reference kettle and the staged parallel sample kettle, respectively; Z3 and Z4 are the gas compression factors at the equilibrium pressures P3 and P4 of the constant volume piston reference kettle and the staged parallel sample kettle to achieve pressure equilibrium, respectively; V R is the volume of the constant volume piston reference kettle, cm 3 ; V f is the total residual free volume in the staged parallel sample reactor; the Gibbs adsorption capacity of the entire adsorption experiment GSE n The formula is as follows: n is the total number of pressure values ​​required for the experiment, GSE n represents the sum of ΔGBE under n test conditions; ΔGBE i is the adsorption capacity of the i-th test pressure value; if it is a multi-component gas, the absolute adsorption capacity of each component is calculated as follows: V ab,i =GBE n,i +GBE n ×ρ free / (ρ ad × i ) where V ab,i is the absolute adsorption amount of component i, mol; GBE n,i is the Gibbs adsorption capacity of component i, mol; GBE n is the total Gibbs adsorption capacity, mol; ρ free ,ρ ad are the free phase and adsorbed phase densities, g / cm 3 ;x i is the molar concentration of component i, mol / L; Step 8: Select a specific pressure value for sample structure analysis. After the system reaches equilibrium, close the No. 1 secondary automatic high-pressure connecting needle valve to saturate the No. 1 sample kettle with a specific pressure environment for 24 hours. Then, use a gas chromatograph to analyze the components of the gas in the No. 1 sample kettle. Disassemble and remove the sample in the No. 1 sample kettle for chemical and physical structure analysis. Step 9: If a specific pressure value is set, after the specific adsorption pressure value experiment is completed, repeat step 5 and use the calculation formula: Where V f1 is the remaining free volume in the No. 1 sample kettle, and the other physical parameters are consistent with the calculation formula in step 5; Step 10. If it is necessary to perform structural analysis on samples at multiple specific pressure values, repeat step 8. After the final adsorption pressure value experiment is completed, open the vent valve and the six-way regulating valve of the constant volume piston reference kettle, connect the exhaust gas treatment chamber, vent the gas in the constant volume piston reference kettle, open the first and second level automatic high pressure connecting needle valves of the sample kettle, and inject the high pressure gas in the inner cavity of the sample kettle into the constant volume piston reference kettle until the pressure value in the inner cavity of the sample kettle reaches the target value. Then, close the first and second level automatic high pressure connecting needle valves of the sample kettle and wait for desorption equilibrium. During this process, the temperature and pressure data acquisition and processing system collects the gas pressure and temperature in the inner cavity of the constant volume piston reference kettle and the sample kettle. When the system pressure fluctuation range is less than 0.1psi / h and the temperature fluctuation range is less than 0.025℃ / h, the desorption experiment under the desorption pressure is considered to be completed. Step 11: Repeat step 9 and gradually reduce the pressure by 1 MPa to carry out the next desorption pressure test until all desorption pressure tests are completed.

2. The staged parallel high-pressure gas constant-pressure adsorption / desorption test method according to claim 1, characterized in that: After step one, perform an airtightness check. The specific operating steps are as follows: fill the gas adsorption system with helium, stabilize the pressure at 1.5 MPa higher than the maximum experimental pressure required for the isothermal adsorption experiment and maintain it for more than 24 hours, adjust the temperature of the thermostat to the reservoir temperature, and continuously observe the computer system page curve. If the pressure indication changes less than 0.1 psi / h and the temperature indication changes less than 0.025°C / h, proceed to step two.

3. A staged parallel high-pressure gas constant-pressure adsorption / desorption test device, used to implement the staged parallel high-pressure gas constant-pressure adsorption / desorption test method according to claim 1 or 2, characterized in that: It includes gas preparation and supply system, gas preparation kettle, constant volume piston reference kettle, staged parallel sample kettle, vacuum system, waste gas buffer system, experimental gas safety monitoring and alarm system, terminal operation and real-time data monitoring system; The gas preparation and supply system is used to prepare and supply gas for the entire stage-type parallel high-pressure gas constant-pressure adsorption / desorption test device. The gas preparation and supply system includes a gas cylinder, a pneumatic valve, a one-way ball valve, an automatic high-pressure needle valve and a filter connected in sequence. The outlet end of the filter is connected to a gas booster pump for gas pressurization. The outlet of the booster pump is connected to multiple groups of gas distribution control modules; the gas preparation and supply system is connected to the gas distribution prefabricated kettle through a pipeline; A gas distribution prefabricated kettle, a constant volume piston reference kettle and a staged parallel sample kettle are arranged in a constant temperature box; the tops of the gas distribution prefabricated kettle, the constant volume piston reference kettle and the staged parallel sample kettle are connected to each other through pipelines; a 1mL piston buffer tube is arranged at the bottom of the gas distribution prefabricated kettle and is connected to a gas chromatograph; the bottom of the constant volume piston reference kettle is connected to a liquid pressure gauge, a liquid storage tank and a precision double-cylinder injection pump; the staged parallel sample kettle comprises a cylindrical outer kettle and six groups of constant volume small volume sample inner kettles evenly arranged in the kettle, and the mass of the sample to be tested is placed in the small volume sample inner kettle, a sample kettle temperature and pressure sensor is arranged on the top of the cylindrical outer kettle of the staged parallel sample kettle, and a safety valve and a first-level automatic high-pressure connecting needle valve are provided on the top of the outer kettle of the staged parallel sample kettle; a second-level automatic high-pressure connecting needle valve is provided on the top of each small volume sample inner kettle; The inner kettle of the staged parallel sample kettle is composed of six groups of detachable 50mL fixed-volume small-volume sample inner kettles connected in parallel. A 1mL piston buffer tube is set on the top of each small-volume sample inner kettle to collect the adsorbed gas in the kettle according to the experimental requirements; during the experiment, helium and a two-stage automatic high-pressure connecting needle valve are used to perform multi-stage residual free volume determination to achieve calibration and closure of the volume of each parallel sample kettle after sample loading to avoid affecting the entire adsorption experiment process; six groups of detachable 50mL fixed-volume small-volume sample inner kettles are connected in parallel to achieve staged structural analysis of the adsorption experiment between the adsorbed gas and the adsorbent material during a series of high-pressure adsorption experiments, which can more accurately carry out the adsorption amount and stage-specific pressure value changes of the adsorbent structure of the high-pressure adsorbed gas and the adsorbent material during the multi-pressure point adsorption experiment; The terminal operation and real-time data monitoring system includes a temperature and pressure data acquisition and processing system and a computer. The temperature and pressure data acquisition and processing system sends data to the computer in real time through a data transmission line. The computer is used to record pressure and temperature data values ​​and draw change curves respectively. The temperature and pressure data acquisition and processing system includes a data transmission line and a signal converter; An experimental gas safety monitoring and alarm system, which is electrically connected to a computer and includes an experimental gas safety alarm module and an experimental gas concentration probe, wherein the experimental gas concentration probe is used to measure the experimental gas concentration in the constant temperature box, and the experimental gas safety alarm module is used to alarm when the experimental gas concentration measured by the experimental gas concentration probe is higher than a set safety value; The vacuum system and the exhaust gas buffer system are respectively connected to the two passages of the six-way regulating valve without interfering with each other; the gas distribution prefabrication kettle, the constant volume piston reference kettle and the stage-type parallel sample kettle are connected to the vacuum system through pipelines, and the pipelines are provided with vacuum valves and six-way regulating valves. The vacuum system includes a vacuum gauge, a dryer and a vacuum pump; the exhaust gas buffer system includes an exhaust gas treatment chamber; by controlling the vacuum valve, the vacuum environment of the gas distribution prefabrication kettle, the constant volume piston reference kettle and the stage-type parallel sample kettle is realized.

4. The staged parallel high-pressure gas constant-pressure adsorption / desorption test device according to claim 3 is characterized in that: A fine-tuning valve and a filter are provided on the connecting pipeline between the gas distribution prefabrication kettle and the constant volume piston reference kettle; on the connecting pipeline between the gas distribution prefabrication kettle and the stage-type parallel sample kettle, a pressure sensor is connected to the top of the kettle body of the gas distribution prefabrication kettle, and a sample kettle temperature and pressure sensor is connected to the top of the outer kettle of the stage-type parallel sample kettle; a first-level automatic high-pressure connecting needle valve is provided on the connecting pipeline between the constant volume piston reference kettle and the outer kettle of the stage-type parallel sample kettle; a reference kettle temperature and pressure sensor is connected to the top of the constant volume piston reference kettle; the pressure sensor of the gas distribution prefabrication kettle, the sample kettle temperature and pressure sensor, and the reference kettle temperature and pressure sensor are all connected to the signal converter of the temperature and pressure data acquisition and processing system through a data transmission line.

5. The staged parallel high-pressure gas constant-pressure adsorption / desorption test device according to claim 3 is characterized in that: The gas distribution and supply system includes several gas cylinders for storing helium and the same or different types of experimental gases; an air intake assembly is installed at the gas outlet end of the gas cylinder, and the air intake assembly includes a pneumatic valve, a one-way ball valve and an automatic high-pressure needle valve arranged in sequence on the gas path. The experimental gas passes through the air intake assembly and then through a filter to finally enter the gas distribution prefabricated kettle.

6. The staged parallel high-pressure gas constant-pressure adsorption / desorption test device according to claim 3 is characterized in that: The inner kettle of the small volume sample is made of high temperature and high pressure resistant 316L stainless steel, which is used to place the test sample and has a pressure resistance of 60MPa.

7. The staged parallel high-pressure gas constant-pressure adsorption / desorption test device according to claim 3 is characterized in that: One passage of the six-way regulating valve is connected to a vacuum gauge, a dryer and a vacuum pump in sequence, and the other passage is connected to the exhaust gas treatment chamber.

8. The staged parallel high-pressure gas constant-pressure adsorption / desorption test device according to claim 3 is characterized in that: The experimental gas concentration probes are set at the upper, middle and lower positions of the side wall of the constant temperature box. There are three groups of probes in total. The probes use two-wire pluggable connections. The type of probe is selected according to the experimental requirements.

9. The staged parallel high-pressure gas constant-pressure adsorption / desorption test device according to claim 3, characterized in that: A gas-sensitive electrode is provided on each small-volume sample inner kettle in the constant-volume piston reference kettle and the stage-type parallel sample kettle, and two sets of internal and external connecting joints are provided on the side wall of the stage-type parallel sample kettle. The corresponding two connecting pipes are respectively connected to the gas chromatograph and the precise small-range liquid injection pump; a 1mL piston buffer tube is provided on the connecting pipe between the precise small-range liquid injection pump and the small-volume sample inner kettle.

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