A CO2-Water-Rock Dynamic Reaction Simulation Device and Experimental Method

Abstract

The present invention discloses a CO₂ - water - rock dynamic reaction simulation device and an experimental method, which relate to the technical field of geochemical water - rock reactions. The simulation device includes a gas - liquid internal circulation system, a CO₂ input and monitoring system, a temperature control system, a pressure control system, and a pH monitoring system. Among them, the gas - liquid internal circulation system includes a core holder for fixing samples and applying confining pressure to the samples, and a circulation pump. This gas - liquid internal circulation system can achieve continuous fluid - solid coupling physical simulation under high - pressure conditions, and continuously monitor the environmental pH and circulating confining pressure at the same time. The CO₂ input and monitoring system can accurately measure the CO₂ injection and discharge amounts, and obtain the CO₂ geological storage capacity and the rock permeability before and after the reaction during the CO₂ - water - rock dynamic reaction process. The present invention simulates the high - temperature and high - pressure environment of the reservoir under in - situ conditions in the laboratory, realizes the simultaneous monitoring of the geochemical response of the CO₂ - water - rock system and the evolution characteristics of the sample permeability, and provides guidance for improving the existing CO₂ enhanced oil and gas recovery and CO₂ geological storage technologies.

Description

Technical Field

[0001] The present invention relates to the technical field of geochemical water-rock reactions, and in particular, to a CO2-water-rock dynamic reaction simulation device and an experimental method. Background Art

[0002] CCUS (Carbon Capture, Utilization and Storage) technology is one of the key technologies to address global climate change. CO2 geological storage is an important part of CCUS technology. Studying the CO2-water-rock reaction characteristics is an effective means for enhanced unconventional oil and gas recovery by CO2. The relevant results help to clarify the mechanisms of caprock leakage and fracture leakage during CO2 geological storage, and provide guidance for the safety evaluation of CO2 storage in oil and gas reservoirs.

[0003] When carrying out CO2 geological storage work, due to the fluctuations of hydrodynamic conditions, temperature and pressure conditions, CO2 will have a certain fluidity inside the reservoir. Under in-situ conditions, the CO2-water-rock mainly exhibits a dynamic reaction process. Existing engineering cases have confirmed that mixing CO2 with water for injection can greatly improve the CO2 storage efficiency. For example, in the world's largest CO2 mineralization project - the CarbFix project in Iceland, water and CO2 are fully mixed and then injected into the target layer through two drilling wells. This scheme can increase the CO2 storage efficiency to more than 95% (Reference: DOI: 10.1126 / science.1250828). However, the experimental devices used in current technical solutions are mainly the first-generation static reactors (such as CN215375410U). This device can only control the CO2 injection process and cannot ensure the continuous flow of the injected CO2 under the pressure gradient. The simulated CO2-water-rock reaction environment does not match the actual injection conditions. In addition, the existing simulation devices can only meet the experiments on rock particles and cannot apply confining pressure to the samples, which will cause the simulation environment to be inconsistent with the reservoir conditions, resulting in the experimental conclusions being deviated from the actual situation. On the other hand, the existing simulation methods are limited to qualitatively carrying out water-rock reactions and lack real-time monitoring of important geological parameters such as the CO2 geological storage volume and rock permeability during the reaction cycle. Therefore, in combination with the current CO2 geological storage engineering frontier technology, it is necessary to improve the existing experimental system through innovative means to form a CO2-water-rock dynamic reaction simulation device and an experimental method. Summary of the Invention

[0004] The purpose of the present invention is to provide a CO2-water-rock dynamic reaction simulation device and an experimental method to solve the above technical problems existing in the prior art.

[0005] To achieve the above object, in one aspect, the present invention provides a CO2-water-rock dynamic reaction simulation device, comprising:

[0006] A gas-liquid internal circulation system, including a circulation pump, a core holder, and a confining pressure pump; the core holder is connected to the confining pressure pump, and is used to fix the sample and apply confining pressure to the sample.

[0007] A CO2 input and monitoring system, including a CO2 gas cylinder, a heated gas storage tank, and a gas flow meter. One gas flow meter is provided before and after the gas-liquid internal circulation system respectively, and is used to measure the CO2 injection amount before the reaction and the CO2 discharge amount after the reaction. The heated gas storage tank is connected to the CO2 gas cylinder and the core holder.

[0008] A temperature control system, including a constant temperature box, and the gas-liquid internal circulation system is arranged in the constant temperature box.

[0009] A pressure control system, including a booster pump arranged between the CO2 gas cylinder and the heated gas storage tank, an air compressor connected to the booster pump, and a plurality of pressure sensors located on the circulation pipeline.

[0010] The above technical solution of the present invention aims to propose a CO2-water-rock dynamic reaction simulation device, which can simulate the high-temperature and high-pressure environment of the reservoir under in-situ conditions in the laboratory, realize the geochemical response of CO2-water-rock while monitoring the evolution characteristics of the sample permeability, and provide guidance for improving the existing CO2 enhanced oil and gas recovery and CO2 geological sequestration technologies.

[0011] Optionally, the core holder is further connected to an N2 gas cylinder, and the N2 gas cylinder is used to perform N2 purging on the core holder.

[0012] Optionally, the CO2-water-rock dynamic reaction simulation device further includes a pH monitoring system, and the pH monitoring system includes a pH controller built in the constant temperature box, and the pH controller is used to regularly monitor the acidity and alkalinity of the solution during the reaction process.

[0013] Optionally, the pressure sensors include a first pressure sensor and a second pressure sensor arranged on the inlet pipeline and the outlet pipeline of the core holder; a first temperature sensor and a second temperature sensor are respectively arranged on the inlet pipeline and the outlet pipeline of the core holder.

[0014] Optionally, the outlet pipeline of the core holder is connected to a back pressure pump, a back pressure valve is arranged between the back pressure pump and the core holder, and the back pressure valve pipeline is connected to a gas-liquid separation system.

[0015] Optionally, the gas-liquid separation system includes a gas-liquid separator, a container connected to the liquid outlet end of the gas-liquid separator, and a gas flow meter connected to the gas outlet end of the gas-liquid separator. The container is placed on an electronic balance, and a desiccant and an exhaust valve are provided on the exhaust pipeline at the front end of the gas flow meter.

[0016] Optionally, a backpressure buffer is provided between the backpressure pump and the backpressure valve.

[0017] In another aspect of the present invention, a CO2-water-rock dynamic reaction experiment method for measuring the geological sequestration amount of CO2 is provided. Using the CO2-water-rock dynamic reaction simulation device described in any one of the above, the method includes the following steps:

[0018] S101. Prepare a columnar sample with a diameter of 2.5 cm and a length of 5 cm from the massive rock, and perform water saturation treatment on the sample;

[0019] S102. After weighing the water-saturated sample, place it in a core holder, apply confining pressure, and turn on the constant temperature box to make it constant at the set value;

[0020] S103. Use N2 to displace and discharge the residual air in the gas-liquid internal circulation system, inject deionized water to discharge the internal N2, record the water injection volume, and then inject CO2 to discharge part of the water in the gas-liquid internal circulation system. After the residual water reaches the set value, close the water outlet valve, and record the CO2 injection volume and the residual water volume;

[0021] S104. Turn on the air compressor and the booster pump to increase the pressure of the gas-liquid internal circulation system. After the pressure reaches the set value, close the booster and intake valves;

[0022] S105. Open the system valve, set the flow rate of the circulation pump to 0-30 mL / min to perform the internal circulation CO2-water-rock dynamic reaction experiment, and record the data of the system pressure changing with time;

[0023] S106. Regularly measure the pH value of the circulation system during the experiment, and monitor the water chemical environment of the internal solution in real time;

[0024] S107. After the experiment, discharge the CO2 in the circulation system through the flow meter, and analyze it with the CO2 injection volume. Then the expression of the total CO2 sequestration amount is:

[0025]

[0026] In the formula: N is the total CO2 sequestration amount, n1 is the CO2 injection volume, and n2 is the CO2 discharge volume;

[0027] The expression of the CO2 dissolution amount is:

[0028]

[0029] wherein, n d is the dissolved amount of CO2, k CO2 is the dissolved amount of CO2 per unit amount of substance, m w is the water content, M w is the molar mass of water;

[0030] Since most oil and gas reservoirs are low-porosity and low-permeability rocks, the content of free and adsorbed physical sequestration states is relatively small after CO2 injection. Therefore, it can be considered that the dissolved state and mineralized state are the main CO2 sequestration forms during the experiment. Combining the previous calculation conclusions on the total CO2 sequestration amount and dissolved amount, the CO2 mineralization amount n m The expression is:

[0031] .

[0032] In another aspect of the present invention, a CO2-water-rock dynamic reaction experiment method for measuring permeability is provided. Using the CO2-water-rock dynamic reaction simulation device described in any one of the above, it includes the following steps:

[0033] S201. Place the sample in the core holder, turn on the constant temperature oven, and keep it constant at the set value;

[0034] S202. Drain the water in the core holder, introduce the gas to be measured and drain the residual gas;

[0035] S203. Increase the pressure in the core holder to the measured value, and record the pressures and gas flow rates at the inlet and outlet;

[0036] S204. Calculate the permeability of the sample according to the sample size, inlet and outlet pressures, and gas flow rate. The calculation formula is:

[0037]

[0038] In the formula, K is the permeability, P0 is the atmospheric pressure, Q is the gas flow rate during the seepage process, μ is the gas viscosity, L is the length of the columnar sample, A is the bottom area of the cylindrical sample, and P1 is the inlet pressure.

[0039] The present invention discloses the following technical effects:

[0040] The device and method of the present invention can be used to conduct dynamic reaction simulation experiments of CO2-water-rock for columnar samples or granular samples. Moreover, without frequent sampling, real-time monitoring of CO2 geological storage capacity and permeability can be achieved; simulation experiments on the geochemical behavior of columnar samples and granular samples with CO2 can be carried out to solve the problem that the applicable sample specifications of existing experimental devices are limited; dynamic reaction experiments of CO2-water-rock and monitoring of the characteristics of permeability change before and after can be carried out to solve the problem of the single function of existing experimental devices; the problem that existing experimental devices cannot ensure the effective contact between CO2 fluid and water and rock samples can also be solved, and to a certain extent, it can truly reflect the flow process of CO2 in the in-situ reservoir after injection. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0042] Figure 1 It is a schematic structural diagram of a CO2-water-rock dynamic reaction simulation device provided by the present invention;

[0043] Figure 2 It is a schematic structural diagram of the gas-liquid internal circulation system of the device of the present invention;

[0044] In the figure: 1. N2 gas cylinder; 2. CO2 gas cylinder; 3. CO2 gas inlet; 4. Booster pump; 5. Solenoid valve; 6. Air compressor; 8. Heated gas storage tank; 9. Pressure regulating valve; 10. Gas flowmeter I; 11. Confining pressure pump; 12. Pressurizing pump; 13. Pressure sensor III; 14. Core holder; 15. Temperature sensor I; 16. Pressure sensor I; 17. Temperature sensor II; 18. Pressure sensor II; 19. Circulation pump; 20. Constant temperature box; 21. Back pressure valve; 22. Back pressure buffer; 23. Back pressure pump; 24. Gas-liquid separator; 25. Electronic balance; 26. Desiccant; 27. Gas flowmeter II; 100. N2 gas inlet valve; 101. Valve I; 102. Valve II; 103. Valve III; 104. Valve IV; 105. Valve V; 106. Valve VI; 107. Valve VII; 108. Valve VIII; 109. Valve IX; 110. Valve X; 111. Valve XI; 112. Valve XII; 113. Valve XIII; 114. Valve XIV; 115. Valve XV; 116. Valve XVI; 117. Valve XVII; 201. Pressure regulating gauge I; 202. Pressure regulating gauge II; 203. Pressure regulating gauge III; 204. Pressure regulating gauge IV; 205. pH controller; 206. Back pressure regulating gauge. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0045] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0046] Currently, the research on CO2-water-rock reactions mainly uses static high-pressure reaction vessels. The simulation experimental device cannot truly reproduce the fluid environment generated after CO2 injection under actual conditions, and the effectiveness and authenticity of the experiments cannot be guaranteed. In addition, the existing analysis methods cannot use the built-in functional modules of the device to monitor the geological CO2 sequestration volume and sample permeability data during the experiment, and the analysis methods supporting the simulation experiments are relatively single.

[0047] How to truly reproduce the dynamic reaction process of CO2-water-rock by technical means and perform periodic monitoring on rock and solution samples during the experimental period is a key technical problem to be solved in this field.

[0048] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0049] Embodiment 1

[0050] Referring to Figure 1 and Figure 2 As shown, Embodiment 1 of the present invention provides a CO2-water-rock dynamic reaction simulation device, including a gas-liquid internal circulation system, a CO2 input and monitoring system, a temperature control system, a pressure control system, and a pH monitoring system.

[0051] The gas-liquid internal circulation system includes a circulation pump 19, a core holder 14, a first pressure sensor 16, a second pressure sensor 18, a first temperature sensor 15, and a second temperature sensor 17; wherein, the circulation pump 19 is further connected to an confining pressure pump 11 and a pressurizing pump 12, and a third pressure sensor 13 is provided on the circulation pipeline between the circulation pump 19 and the confining pressure pump 11. The pressure conditions that the circulation pump 19 can meet are 0-20 MPa, and the flow rate can be set to 0-30 mL / min; the core holder 14 is used to fix the sample and apply confining pressure to the sample to simulate the formation environment, and the confining pressure range that can be met is 0-30 MPa; the pressure sensors are used to measure the inlet and outlet pressures of the holder.

[0052] The described CO2 input and monitoring system includes a gas flowmeter, a heated gas storage tank 8, and multiple pressure sensors; one gas flowmeter is provided before and after the gas-liquid internal circulation system respectively, including gas flowmeter 10 and gas flowmeter 27, which are used to measure the CO2 injection volume before the reaction and the CO2 discharge volume after the reaction; the heated gas storage tank 8 is connected to the CO2 gas cylinder 2 and the core holder 14, and its main purpose is to pre-heat and pressurize the injected CO2 gas to ensure a stable injection state; the pressure sensors are used to measure the pressures of the CO2 gas cylinder 2 and the heated gas storage tank 8.

[0053] The described temperature control system includes a constant temperature box 20, which is an electric heating constant temperature box located outside the internal circulation system and is used to keep the temperature of the gas-liquid internal circulation system constant, and the temperature conditions that can be satisfied are 0~100°C.

[0054] The described pressure control system mainly includes a booster pump 4, an air compressor 6, and multiple pressure sensors; the booster pump 4 is located at the rear of the CO2 gas cylinder 2 and is used to inject the CO2 released from the CO2 gas cylinder 2 into the gas storage tank, and the pressure conditions that can be satisfied are 0~30 MPa; the air compressor 6 is connected to the booster pump 4 and can provide power for the CO2 injection process; the pressure sensors are used to measure the gas pressure at the outlet of the booster pump 4.

[0055] The described pH monitoring system mainly includes a pH controller 205, which is built into the constant temperature box 20 and is used to regularly monitor the acidity and alkalinity of the solution during the reaction to ensure the continuous progress of the CO2-water-rock reaction.

[0056] As Figure 1 shown, the gas-liquid internal circulation system is connected to the CO2 gas cylinder 2 through a circulation pipeline. Among them, the following are sequentially arranged on the circulation pipeline from the CO2 gas cylinder 2 to the core holder 14: a CO2 gas inlet 3, a pressure regulator 202, a valve 101, a booster pump 4, a valve 103, a heated gas storage tank 8, a valve 105, a pressure regulating valve 9, a pressure regulator 203, a valve 106, a gas flowmeter 10, a valve 107, and a valve 110. A valve 102 is provided at the front end of the booster pump 4, and the valve 102 is a pipeline vent valve. A valve 104 is provided at the front end of the heated gas storage tank 8, and the valve 104 is a gas storage tank vent valve. An electromagnetic valve 5 is provided between the heated gas storage tank 8 and the air compressor 6, and the heated gas storage tank 8 is also connected to a pressure regulator 204.

[0057] The gas-liquid internal circulation system is connected to the N2 gas cylinder 1 through a gas pipeline. Among them, the following are sequentially arranged on the gas pipeline from the N2 gas cylinder 1 to the core holder 14: a pressure regulator 201 and an N2 gas inlet valve 100.

[0058] A valve eleven 111 and a valve twelve 112 are provided between the core holder 14 and the circulation pump 19. A valve fifteen 115 is further provided at the rear end of the core holder 14. The valve fifteen 115 is a pipeline vent valve. A valve sixteen 116 is provided on the pipeline between the core holder 14 and the back pressure valve 21. A valve nine 109 is provided between the core holder 14 and the confining pressure pump 11. A valve eight 108 is provided between the core holder 14 and the pressurizing pump 12. A valve seventeen 117 is provided between the core holder 14 and the pH controller 205. The valve seventeen 117 is a water intake valve.

[0059] On the back pressure pipeline between the back pressure pump 23 and the gas-liquid internal circulation system, a valve thirteen 113, a back pressure buffer 22, and a back pressure valve 21 are successively provided. A back pressure regulating gauge 206 is further provided at the front end of the back pressure pump 23. The back pressure valve 21 is connected to the gas-liquid separator 24 through an exhaust pipeline. A container (such as a beaker) is placed at the liquid discharge end of the gas-liquid separator 24 for receiving liquid. The container is placed on an electronic balance 25. The gas discharge end of the gas-liquid separator 24 is connected to a desiccant 26 through a valve fourteen 114 (exhaust valve), and the dried gas treated by the desiccant 26 is discharged through a gas flowmeter two 27.

[0060] Embodiment 2

[0061] Embodiment 2 of the present invention provides a CO2-water-rock dynamic reaction experiment method for measuring the geological sequestration amount of CO2. This method uses the CO2-water-rock dynamic reaction simulation device of Embodiment 1 and includes the following steps:

[0062] S101. Prepare a columnar sample with a diameter of 2.5 cm and a length of 5 cm from the massive rock, and perform water saturation treatment on the sample;

[0063] In some embodiments, the massive rock is directly prepared into a columnar sample with a diameter of 2.5 cm and a length of 5 cm. Then, after weighing the above-mentioned water-saturated columnar sample, the CO2-water-rock reaction experiment can be directly carried out;

[0064] In other embodiments, the massive rock is prepared into granular particles with a particle size of 50-500 μm, and then water saturation is carried out. The water-saturated granular sample is placed in a CO2-resistant rubber sleeve with a diameter of 2.5 cm and a length of 5 cm, and both ends are blocked and formed to obtain a columnar sample, which can be used for the subsequent CO2-water-rock reaction experiment.

[0065] S102. After weighing the water-saturated sample, place it in the core holder 14, apply confining pressure, and turn on the constant temperature box 20 to make it constant at the set value;

[0066] In a specific embodiment, before putting the sample, first check whether there is system pressure in the pipeline, confirm the pressure situation of the system by turning on the power supply. If there is pressure in the pipeline, first relieve the pressure;

[0067] After confirming the system pressure, open the inlet and outlet ends of the core holder 14, load the sample and the dummy core, and tighten the inlet and outlet plugs.

[0068] Check whether the digital display instrument shows normally, turn on the computer, and start the operating software.

[0069] Close all valves, adjust the pressure regulating valve 9 to the closed state, and install and open the corresponding valves in sequence during operation.

[0070] In a specific embodiment, step S102 includes: opening valve nine 109, adjusting the pressure of the core holder 14 by starting the confining pressure pump 11. The confining pressure pump 11 can be controlled automatically or manually. If the initial experimental pressure is low, directly boost the pressure to the experimental pressure; if the initial experimental pressure is high, first pressurize to 5 Mpa, and at the same time boost the pressure of the internal circulation, and keep the confining pressure always 2 MPa higher than the internal pressure.

[0071] In a specific embodiment, the adjustment of the initial pressure value includes: opening the gas cylinder, and at the same time opening valve one 101 and valve three 103, pressing the boost start button on the control panel to increase the pressure in the heated gas storage tank 8 to 20 MPa, closing valve three 103, opening valve five 105, and adjusting the output pressure to the test initial pressure through the pressure regulating valve 9.

[0072] S103. Use N2 to displace and discharge the residual air in the gas-liquid internal circulation system, inject deionized water to discharge the internal N2, record the water injection volume, and then inject CO2 to discharge part of the water in the gas-liquid internal circulation system. After the residual water reaches the set value, close the water outlet valve, and record the CO2 injection volume and the residual water volume.

[0073] In a specific embodiment, open the N2 gas inlet valve 100 and valve ten 110, keep valve eleven 111 and valve twelve 112 closed, introduce nitrogen, open valve fifteen 115, and use nitrogen to purge the pipeline. Among them, the N2 gas cylinder 1 is filled with high-purity nitrogen.

[0074] Then, close the N2 gas inlet valve 100, open valve eight 108 and valve eleven 111, start the pressure pump 12 to inject experimental water into the pipeline, displace the nitrogen in the pipeline and the sample, open the outlet of valve fifteen 115 and use a beaker to collect the liquid, and stop injecting water after the nitrogen is fully discharged, and record the water injection volume.

[0075] S104. Open the air compressor 6 and the booster pump 4 to boost the pressure of the gas-liquid internal circulation system. After the pressure reaches the set value, close the boost and inlet valves.

[0076] Specifically, close valve eight 108 and valve fifteen 115, open valve six 106, valve seven 107, valve eleven 111, and valve twelve 112. Inject CO2 into the core holder 14 according to the preset experimental pressure. After reaching the expected pressure, close valve twelve 112;

[0077] S105. Open the system valves, turn on the circulation pump 19, set a constant flow rate within the range of 0 - 30 mL / min, conduct an in - cycle CO2 - water - rock dynamic reaction experiment, and record the data of the system pressure changing with time;

[0078] S106. During the experiment, regularly measure the pH value of the circulation system through the water intake valve (valve seventeen 117). Meanwhile, use the pH controller 205 to monitor the internal solution hydrochemical environment in real - time;

[0079] S107. After the experiment, discharge the CO2 in the circulation system through the flowmeter, and analyze it together with the CO2 injection amount. Then the expression for the total CO2 sequestration amount is:

[0080]

[0081] In the formula: N is the total CO2 sequestration amount, n1 is the CO2 injection amount, and n2 is the CO2 discharge amount;

[0082] The expression for the CO2 dissolution amount is:

[0083]

[0084] where, n d is the CO2 dissolution amount, k CO2 is the CO2 dissolution amount per unit amount of substance, m w is the water content, M w is the molar mass of water;

[0085] Since most oil - gas reservoirs are low - porosity and low - permeability rocks, after CO2 injection, the content of free and adsorbed physical sequestration states is relatively small. Therefore, it can be considered that the dissolved state and mineralized state are the main CO2 sequestration forms during the experiment; combining the previous calculation conclusions on the total CO2 sequestration amount and dissolution amount, the expression for the CO2 mineralization amount n m is:

[0086]

[0087] where, n m is the CO2 mineralization amount, w0 is the weight of the dry sample before the experiment, and w1 is the weight of the dry sample after the experiment.

[0088] In a specific embodiment, at the end of the experiment, the backpressure pump 23 is used to increase the backpressure to the experimental pressure. Valve sixteen 116 is opened, and the gas-liquid mixture in the pump and pipeline is released into the gas-liquid separator 24 through the backpressure valve 21. Valve fourteen 114 is opened, and the gas volume is measured by gas flowmeter two 27 and the liquid volume is measured by electronic balance 25 respectively. The gas can be collected using a gas collection bag at the outlet of gas flowmeter two 27. After the experiment, according to the internal pressure, the confining pressure is slowly reduced. After the pressure is released, the inlet and outlet ends are disassembled and the sample is taken out.

[0089] Example 3

[0090] Example 3 of the present invention provides another CO2-water-rock dynamic reaction experiment method for determining permeability. This method uses the CO2-water-rock dynamic reaction simulation device of Example 1 and includes the following steps:

[0091] S201. Place the sample in the core holder 14 and turn on the constant temperature oven 20 to make it constant at the set value.

[0092] S202. Drain the moisture in the core holder 14, introduce the gas to be measured and discharge the residual gas.

[0093] S203. Increase the pressure in the core holder 14 to the measurement value, and record the pressures and gas flows at the inlet and outlet.

[0094] S204. Calculate the permeability of the sample based on the sample size, inlet and outlet pressures, and gas flow. The calculation formula is:

[0095]

[0096] In the formula, K is the permeability, P0 is the atmospheric pressure, Q is the gas flow during the seepage process, μ is the gas viscosity, L is the length of the columnar sample, A is the bottom area of the cylindrical sample, and P1 is the inlet pressure.

[0097] Specifically, in a specific embodiment, the CO2-water-rock dynamic reaction simulation device of Example 1 is adopted, and the following operating steps are included:

[0098] Turn on the power supply and observe whether there is residual pressure in the pipeline. If there is pressure, release the pressure through the vent valve. Unscrew the plug at the outlet end of the core holder 14, load the sample, and tighten the plug. Close all valves and turn on the constant temperature oven 20.

[0099] First, open valve nine 109 and use the confining pressure pump 11 to inject the confining pressure liquid. If the experimental pressure is low, it can be directly increased to the experimental pressure. If the experimental pressure is high, it is first increased to 5 MPa.

[0100] Connect the N2 gas cylinder 1 to the inlet, open valve 101 and valve 103, use the booster pump 4 to boost the pressure to 20 MPa, open valve 105, adjust the pressure regulating valve 9 to the experimental pressure, open valve 106, valve 107, valve 110, valve 113, valve 116, use the back-pressure pump 23 to apply back-pressure to the set pressure, and open valve 116;

[0101] Through the software on the computer and the collected temperature and pressure data, calculate the permeability of the sample;

[0102] After the experiment, according to the internal pressure, slowly reduce the confining pressure. After the pressure is released, disassemble the inlet and outlet ends and take out the sample.

[0103] Compared with the prior art, the present invention discloses at least the following beneficial effects:

[0104] By setting up a gas-liquid internal circulation system, the present invention can realize the dynamic reaction simulation experiment of CO2-water-rock for columnar samples or granular samples; moreover, without frequent sampling, it can realize the real-time monitoring of CO2 geological storage capacity and permeability. The experimental device of the present invention can simulate the experimental study on the geochemical behavior of columnar samples and granular samples with CO2, solve the problem that the applicable sample specifications of the existing experimental devices are limited, and can carry out the dynamic reaction experiment of CO2-water-rock and the monitoring of the change characteristics of the permeability before and after, solving the problem of the single function of the existing experimental devices. The present invention also solves the problem that the existing experimental devices cannot ensure the effective contact between CO2 fluid and water and rock samples, and to a certain extent can truly reflect the flow process of CO2 in the in-situ reservoir after injection.

[0105] Compared with the experimental devices and methods of the prior art, the present invention can ensure that CO2 can be fully dissolved after injection, and the continuity of its reaction can be guaranteed. CO2 continuously flows in the whole system, used to simulate the high-pressure CO2 injection environment on site, which can ensure the full dissolution of CO2 and the continuous occurrence of chemical reactions.

[0106] The details not elaborated in the present invention are all conventional technical means well known to those skilled in the art.

[0107] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "longitudinal", "transverse", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, and is only for the convenience of describing the present invention, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0108] The embodiments described above are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the spirit of the present invention's design, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A CO2-water-rock dynamic reaction simulation device, characterized in that, Comprising: A gas-liquid internal circulation system, including a circulation pump (19), a core holder (14), and an confining pressure pump (11); the core holder (14) is connected to the confining pressure pump (11) for fixing a sample and applying confining pressure to the sample; an outlet pipeline of the core holder (14) is connected to a back pressure pump (23), and a back pressure valve (21) is provided between the back pressure pump (23) and the core holder (14); A CO2 input and monitoring system, including a CO2 gas cylinder (2), a heated gas storage tank (8), and gas flow meters. One gas flow meter is provided before and after the gas-liquid internal circulation system respectively, for measuring the CO2 injection amount before the reaction and the CO2 discharge amount after the reaction. The heated gas storage tank (8) is connected to the CO2 gas cylinder (2) and the core holder (14), for preheating the CO2 in the CO2 gas cylinder (2) and then injecting it into the gas-liquid internal circulation system; A temperature control system, including a constant temperature box (20), and the gas-liquid internal circulation system is arranged in the constant temperature box (20); A pressure control system, including a booster pump (4) arranged between the CO2 gas cylinder (2) and the heated gas storage tank (8), an air compressor (6) connected to the booster pump (4), and a plurality of pressure sensors located on the circulation pipeline; A gas-liquid separation system, the pipeline is connected to the back pressure valve (21). The gas-liquid separation system includes a gas-liquid separator (24), a container connected to the liquid outlet end of the gas-liquid separator (24), and a gas flow meter (27) connected to the gas outlet end of the gas-liquid separator. The container is placed on an electronic balance (25), and a desiccant (26) and an exhaust valve are arranged on the exhaust pipeline in front of the gas flow meter (27); a back pressure buffer (22) is provided between the back pressure pump (23) and the back pressure valve (21).

2. The CO2-water-rock dynamic reaction simulation device according to claim 1, wherein The core holder (14) is further connected to an N2 gas cylinder (1), and the N2 gas cylinder (1) is used for N2 purging of the core holder (14).

3. The CO2-water-rock dynamic reaction simulation device according to claim 1, wherein It further includes a pH monitoring system, and the pH monitoring system includes a pH controller (205) built in the constant temperature box (20), and the pH controller (205) is used for periodically monitoring the acidity and alkalinity of the solution during the reaction process.

4. The CO2-water-rock dynamic reaction simulation device according to claim 1, characterized in that, The pressure sensors include a pressure sensor one (16) and a pressure sensor two (18) arranged on the inlet pipeline and the outlet pipeline of the core holder (14); temperature sensors one (15) and two (17) are respectively arranged on the inlet pipeline and the outlet pipeline of the core holder (14).

5. A CO2-water-rock dynamic reaction experimental method for determining the geological storage capacity of CO2, characterized in that, Using the CO2-water-rock dynamic reaction simulation device according to any one of claims 1 to 4, including the following steps: S101. Prepare a columnar sample with a diameter of 2.5 cm and a length of 5 cm from massive rock, and perform water saturation treatment on the sample; S102. After weighing the water-saturated sample, place it in the core holder (14), apply confining pressure, and turn on the constant temperature box (20) to make it constant at the set value; S103. Use N2 to displace and discharge the residual air in the gas-liquid internal circulation system, inject deionized water to discharge the internal N2, record the water injection volume, and then inject CO2 to discharge part of the water in the gas-liquid internal circulation system. After the residual water reaches the set value, close the water outlet valve, and record the CO2 injection volume and the residual water volume; S104. Open the air compressor (6) and the booster pump (4) to pressurize the gas-liquid internal circulation system. After the pressure reaches the set value, close the pressurization and intake valves; S105. Open the system valve, set the flow rate of the circulation pump (19) to 0 - 30 mL / min for the internal circulation CO2-water-rock dynamic reaction experiment, and record the data of the system pressure changing with time; S106. Regularly measure the pH value of the circulation system during the experiment to monitor the water chemical environment of the internal solution in real time; S107. After the experiment, discharge the CO2 in the circulation system through the flowmeter, and analyze it with the CO2 injection volume. Then the expression of the total CO2 sequestration amount is: Where: N is the total CO2 sequestration amount, n1 is the CO2 injection volume, and n2 is the CO2 discharge volume; The expression of the CO2 dissolution amount is: where n d is the amount of CO2 dissolved, k CO2 is the amount of CO2 dissolved per unit amount of substance, m w is the water content, M w is the molar mass of water; Combined with the calculation results of the total amount and dissolved amount of CO2 sequestration in the early stage, the mineralization amount n of CO2 is obtained m The expression is as follows: 。 6. A CO2-water-rock dynamic reaction experimental method for determining permeability, characterized in that, Using the CO2-water-rock dynamic reaction simulation device described in any one of claims 1 to 4, includes the following steps: S201. Place the sample in the core holder (14), and turn on the constant temperature oven (20) to make it constant at the set value; S202. Drain the water in the core holder (14), introduce the gas to be measured and discharge the residual gas; S203. Increase the pressure in the core holder (14) to the measured value, and record the pressures and gas flow rates at the inlet and outlet; S204. Calculate the permeability of the sample according to the sample size, inlet and outlet pressures, and gas flow rate. The calculation formula is: Where, K is the permeability, P0 is the atmospheric pressure, Q is the gas flow rate during the seepage process, μ is the gas viscosity, L is the length of the columnar sample, A is the bottom area of the cylindrical sample, and P1 is the inlet pressure.

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