A device and method for quantitative assessment of CO2 sequestration and salt precipitation in saline aquifers

Abstract

This invention discloses a device and method for quantitatively assessing CO2 sequestration and salt precipitation in saline aquifers. The device comprises a fluid injection system, a core reaction system, a confining pressure system, a back pressure system, a pulse measurement system, a drainage system, and a data analysis system. The fluid injection system, confining pressure system, back pressure system, and drainage system are all connected to the core reaction system. The pulse measurement system and the data analysis system are electrically connected to the core reaction system. In this embodiment, the core reaction system provides the experimental environment, the fluid injection system provides the required scCO2 and brine, the pulse measurement system provides acoustic signals to the rock sample, and the data analysis system analyzes the collected data to obtain the quantitative assessment results of CO2 sequestration and salt precipitation in saline aquifers, providing a scientific basis for the injection process and sequestration safety of CO2 geological sequestration.

Description

Technical Field

[0001] This invention relates to the field of geological simulation technology, and in particular to a device and method for quantitative evaluation of CO2 sequestration and salt precipitation in saline aquifers. Background Technology

[0002] Carbon capture, utilization, and storage (CCUS) is one of the key technologies for achieving carbon neutrality. Among these, geological CO2 storage is the primary option for large-scale CO2 storage, referring to the process of injecting CO2 into deep underground reservoirs for long-term preservation. Saline aquifers are considered the most suitable locations for CO2 storage due to their wide distribution, large storage capacity, and high safety. However, with the continuous injection of large amounts of dry CO2, the water in the saline aquifer evaporates, the salt solution reaches a supersaturated state, and crystallizes near the injection well. This salting-out process leads to pore blockage, reducing the reservoir's porosity and permeability, severely impacting CO2 injection efficiency.

[0003] Currently, researchers primarily employ core experiments and microfluidic technology in salting-out studies: at the core scale, they investigate changes in porosity, permeability, and capillary pressure in rock samples after CO2 injection into saline aquifers, and analyze the effects of mineral composition, CO2 injection rate, and brine salinity on CO2 injection capacity. Although CT scans are increasingly used for three-dimensional imaging of the CO2 injection process, operational limitations prevent real-time image capture, resulting in significant shortcomings in real-time monitoring of the salting-out process. While chip experiments allow direct observation of the salting-out process and analysis of the dynamic mechanisms at the pore scale, the experimental size is extremely small compared to the actual scale, and the complexity of real-world strata far exceeds the simulation capabilities of microfluidic devices, limiting experimental accuracy. Furthermore, microfluidic technology itself may have limitations; for example, the shape of the pore channels and the materials used can affect experimental results. In addition, the high-resolution imaging and complex data processing required by microfluidic technology significantly increase the difficulty of data analysis.

[0004] Therefore, there is an urgent need for a new device or method to accurately and in real-time quantitatively analyze the salting-out phenomenon during CO2 sequestration in saline aquifers. Summary of the Invention

[0005] In view of the above problems, the present invention is proposed to provide a device and method for quantitative assessment of CO2 sequestration and salting out in saline aquifers to overcome or at least partially solve the above problems.

[0006] Other features and advantages of the invention will become apparent from the following detailed description, or may be learned in part by practice of the invention.

[0007] According to a first aspect of the present invention, a quantitative assessment device for CO2 geological sequestration and salt precipitation in a saline aquifer is provided. The device comprises: a fluid injection system, a core reaction system, a confining pressure system, a back pressure system, a pulse measurement system, a drainage system, and a data analysis system. The fluid injection system, confining pressure system, back pressure system, and drainage system are respectively connected to the core reaction system, and the pulse measurement system and the data analysis system are respectively electrically connected to the core reaction system.

[0008] The fluid injection system is used to inject fluid into the core reaction system, the fluid including CO2 and brine;

[0009] The core reaction system provides an experimental environment for reaction experiments on rock samples.

[0010] The confining pressure system is used to apply confining pressure to the rock sample in the core reaction system;

[0011] The back pressure system is used to provide back pressure for the core reaction system;

[0012] The pulse measurement system is used to generate a pulse signal that excites the rock sample and to receive the received signal after it passes through the rock sample;

[0013] The drainage system is used to receive the fluid waste liquid discharged from the core reaction system;

[0014] The data analysis system is used to collect and analyze the data from the core reaction system reaction experiment to obtain quantitative assessment results of CO2 geological sequestration and salting out in the saline aquifer.

[0015] In some embodiments of the present invention, the fluid injection system includes a CO2 cylinder, a brine container, a constant-speed and constant-pressure pump, and a brine injection pump; the CO2 cylinder is connected to the core reaction system via a CO2 injection pipeline, and a CO2 injection control valve and a constant-speed and constant-pressure pump are respectively installed on the CO2 injection pipeline; the brine container is connected to the core reaction system via a brine injection pipeline, and a brine injection pump, a first brine injection control valve, and a second brine injection control valve are respectively installed on the brine injection pipeline, with the first brine injection control valve located between the brine container and the brine injection pump, and the second brine injection control valve located between the brine injection pump and the core reaction system.

[0016] In some embodiments of the present invention, the core reaction system includes a core support, a reaction vessel, a temperature and pressure sensor, a transmitting probe, and a receiving probe; the reaction vessel is horizontally disposed on the upper end of the core support and is used to contain the rock sample; the temperature and pressure sensor, the transmitting probe, and the receiving probe are respectively disposed inside the reaction vessel, the temperature and pressure sensor is electrically connected to the data analysis system, the transmitting probe and the receiving probe are respectively disposed on symmetrical sides of the rock sample, and the transmitting probe and the receiving probe are electrically connected to the pulse measurement system; the reaction vessel is respectively connected to the fluid injection system and the drainage system.

[0017] In some embodiments of the present invention, the reactor is also connected to a vacuum pump via an extraction pipe.

[0018] In some embodiments of the present invention, the confining pressure system includes a confining pressure circulation pump, a first hydraulic loading control valve, a second hydraulic loading control valve, and a liquid storage container. The liquid storage container is connected to the reactor via a hydraulic oil pipeline. The confining pressure circulation pump, the first hydraulic loading control valve, and the second hydraulic loading control valve are respectively installed on the hydraulic oil pipeline. The first hydraulic loading control valve is located between the confining pressure circulation pump and the liquid storage container, and the second hydraulic loading control valve is located between the confining pressure circulation pump and the reactor.

[0019] In some embodiments of the present invention, the back pressure system includes an oil tank, a first back pressure oil injection control valve, a second back pressure oil injection control valve, and a back pressure pump. The oil tank is connected to the reactor through a back pressure oil injection pipeline, and the second back pressure oil injection control valve and the back pressure pump are respectively installed on the back pressure oil injection pipeline.

[0020] In some embodiments of the present invention, a temperature control system is provided on the outside of the reaction vessel. The temperature control system includes a heating plate and a heat insulation cover, wherein the heating plate is disposed on the bottom surface of the reaction vessel, and the heat insulation cover is arranged around the outside of the reaction vessel.

[0021] In some embodiments of the present invention, the pulse measurement system includes a pulse generator, a preamplifier, and an oscilloscope. The pulse generator is electrically connected to the transmitting probe via a wire, and the oscilloscope, the preamplifier, and the receiving probe are electrically connected in sequence via wires.

[0022] In some embodiments of the present invention, the drainage system includes a drainage pipeline, a drainage filter valve, a drainage control valve, and a waste liquid storage container. The waste liquid storage container is connected to the reaction vessel through the drainage pipeline, and the drainage pipeline is respectively equipped with a drainage filter valve and a drainage control valve.

[0023] According to a second aspect of the present invention, a method for quantitatively assessing CO2 geological sequestration and salting out in saline aquifers is provided, comprising the following steps:

[0024] S1: Weigh the clean and dry rock sample, and then use micron CT to take a high-resolution image of the rock sample to obtain the first image data;

[0025] S2: The transmitting probe and the receiving probe are symmetrically arranged on both sides of the column of the rock sample, and then wrapped with polytetrafluoroethylene and aluminum foil from the inside to the outside and placed in a rubber sleeve to uniformly transfer the confining pressure. Then it is put into the reaction vessel, and the rock sample is fixed by the pad block.

[0026] S3: Connect the fluid injection system, confining pressure system, back pressure system, and drainage system to the core reaction system respectively, and flush the corresponding pipelines with toluene, formaldehyde, and distilled water, and then dry them with nitrogen; and electrically connect the pulse measurement system and data analysis system to the core reaction system respectively.

[0027] S4: Turn on the electric heating plate to raise the temperature in the reactor to the target value and stabilize it for 8 hours. Apply confining pressure to the rock sample through the confining pressure system. Turn on the fluid injection system to inject gaseous CO2 into the rock sample to remove the original air and water vapor in the pore space. Then use a vacuum pump to evacuate the rock sample for at least 24 hours to ensure that there is no air residue in the pore throat. When the vacuum pump is working, turn off the fluid injection system and then turn on the back pressure system to apply back pressure to the rock sample.

[0028] S5: Open the fluid injection system to inject brine into the rock sample until the core sample reaches saturation. At the same time, open the drain filter valve and drain control valve of the drain system to discharge the experimental waste liquid.

[0029] S6: Open the fluid injection system to increase CO2 to the target pressure, and then inject it into the reactor at a constant rate in a supercritical phase. During the injection process, the waste liquid discharge system remains open.

[0030] S7: During the reactor experiment, turn on the temperature and pressure sensors, pulse generator, preamplifier and oscilloscope to monitor the temperature data, pressure data and acoustic signal data during the experiment.

[0031] S8: After the reaction is complete, drain the pore fluid from the rock sample, and then perform confining pressure unloading and cooling treatment.

[0032] S9: Take samples of solid products attached to the surface of rock samples for composition analysis;

[0033] S10: The data analysis system processes and analyzes the acoustic signal data monitored in real time during the experiment, and calculates the first volume of salt precipitated.

[0034] S11: High-resolution images of the rock samples after the experiment were captured using micron-CT to obtain the second image data;

[0035] S12: Based on the first and second image data of the rock sample, extract the first porosity of the rock sample before the experiment and the second porosity of the rock sample after the experiment, and calculate the second volume of salt precipitated during the experiment by subtracting the first image data and the second image data of the rock sample after the experiment.

[0036] S13: Calculate the error value based on the first and second volumes of precipitated salt, and confirm whether the error value is within the preset threshold range to obtain the quantitative assessment result of CO2 geological sequestration salt precipitation in the saline aquifer.

[0037] The technical solutions provided in the embodiments of the present invention have at least the following technical effects or advantages:

[0038] The present invention relates to a quantitative assessment device and method for CO2 geological sequestration salting out in saline aquifers. The device utilizes a core reaction system to provide the experimental environment, a fluid injection system to provide the required scCO2 and brine, a pulse measurement system to provide acoustic signals to the rock samples, and a data analysis system to analyze the collected data and obtain quantitative assessment results for CO2 geological sequestration salting out in saline aquifers. This enables real-time, non-destructive monitoring and calculation of salting out at the core scale, thereby revealing the salting out mechanism of CO2 geological sequestration in saline aquifers more profoundly, proposing more accurate methods and strategies to mitigate salting out, and providing a scientific basis for the injection process and sequestration safety of CO2 geological sequestration.

[0039] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0040] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0041] Figure 1 This is a schematic diagram of the principle structure of a quantitative assessment device for CO2 geological sequestration and salt precipitation in a saline aquifer, provided in an embodiment of the present invention.

[0042] Figure 2 This is a magnified schematic diagram of the rock sample area;

[0043] Figure 3 A waveform diagram of the acoustic signal acquired by the oscilloscope;

[0044] Figure 4 This is a flowchart illustrating a quantitative assessment method for CO2 geological sequestration and salting out in saline aquifers, provided as an embodiment of the present invention.

[0045] Explanation of reference numerals in the attached figures:

[0046] 1. CO2 cylinder; 2. CO2 injection line; 3. CO2 injection control valve; 4. Constant speed and constant pressure pump; 5. Constant speed and constant pressure pump injection valve; 6. Constant speed and constant pressure pump discharge valve; 7. Brine container; 8. Brine; 9. First brine injection control valve; 10. Brine injection line; 11. Brine injection pump; 12. Second brine injection control valve; 13. Oil tank; 14. Back pressure oil; 15. Back pressure oil line; 16. First back pressure oil injection control valve; 17. Back pressure pump; 18. Second control valve for back pressure oil injection; 19. Liquid storage container; 20. Hydraulic oil; 21. Hydraulic oil pipeline; 22. First control valve for hydraulic loading; 23. Confining pressure circulation pump; 24. Second control valve for hydraulic loading; 25. Vacuum pump; 26. Evacuation pipe; 27. Core support; 28. Reactor cover; 29. ​​Reactor; 30. Heat shield; 31. Hot plate; 32. Rock sample; 33. Pulse generator; 34. Wire; 35. Transmitting probe; 36. Receiving probe; 37. Preamplifier; 38. Oscilloscope; 39. Temperature and pressure sensor; 40. Data analysis system; 41. Drainage pipeline; 42. Drainage filter valve; 43. Drainage control valve; 44. Waste liquid storage container; 45. Experimental waste liquid. Detailed Implementation

[0047] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings.

[0048] The accompanying drawings illustrate various structural schematics according to embodiments of the present disclosure. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0049] In the context of this disclosure, when a layer / component is referred to as being "above" another layer / component, that layer / component may be directly above the other layer / component, or there may be an intermediate layer / component between them. Additionally, if a layer / component is "above" another layer / component in one orientation, then when the orientation is reversed, that layer / component may be "below" the other layer / component. In the context of this disclosure, similar or identical components may be denoted by the same or similar reference numerals.

[0050] To better understand the above technical solutions, the following will describe the above technical solutions in detail with reference to specific implementation methods. It should be understood that the embodiments of this disclosure and the specific features in the embodiments are detailed descriptions of the technical solutions of the present invention, rather than limitations on the technical solutions of the present invention. In the absence of conflict, the embodiments of the present invention and the technical features in the embodiments can be combined with each other.

[0051] Figure 1 This is a flowchart illustrating a quantitative assessment device and method for CO2 geological sequestration and salting out in saline aquifers provided in an embodiment of the present invention. Figure 1 As shown, the quantitative assessment device for CO2 geological sequestration and salt precipitation in saline aquifers includes: a fluid injection system, a core reaction system, a confining pressure system, a back pressure system, a pulse measurement system, a drainage system, and a data analysis system 40; the fluid injection system, confining pressure system, back pressure system, and drainage system are respectively connected to the core reaction system, and the pulse measurement system and the data analysis system 40 are respectively electrically connected to the core reaction system;

[0052] The fluid injection system is used to inject fluid into the core reaction system, the fluid including CO2 (or supercritical scCO2) and brine 8; the core reaction system provides an experimental environment for the reaction experiment of rock sample 32; the confining pressure system is used to apply confining pressure to rock sample 32 in the core reaction system; the back pressure system is used to provide back pressure to the core reaction system to prevent backflow of brine 8; the pulse measurement system is used to generate a pulse signal to excite rock sample 32 and receive the received signal after passing through rock sample 32, which can monitor the pulse propagation time during the experiment and realize real-time monitoring of the longitudinal wave velocity when salt precipitation occurs in the experiment; the drainage system is used to receive the fluid waste liquid discharged by the core reaction system; the data analysis system 40 is used to collect and analyze the data of the reaction experiment of the core reaction system to obtain the quantitative assessment results of CO2 geological sequestration and salt precipitation in the saline aquifer.

[0053] In this embodiment of the invention, the fluid injection system includes a CO2 cylinder 1, a brine container 7, a constant speed and constant pressure pump 4, and a brine injection pump 11. The CO2 cylinder 1 is connected to the core reaction system via a CO2 injection pipeline 2, and the CO2 injection pipeline 2 is respectively equipped with a CO2 injection control valve 3 and a constant speed and constant pressure pump 4. The brine container 7 is connected to the core reaction system via a brine injection pipeline 10, and the brine injection pipeline 10 is respectively equipped with a brine injection pump 11, a first brine injection control valve 9, and a second brine injection control valve 12. The first brine injection control valve 9 is located between the brine container 7 and the brine injection pump 11, and the second brine injection control valve 12 is located between the brine injection pump 11 and the core reaction system.

[0054] The CO2 cylinder 1 is controlled by the CO2 injection control valve 3. The CO2 cylinder 1 is connected to the injection valve of the constant speed and pressure pump 4 through the CO2 injection pipeline 2. After the flow rate and pressure of the fluid are controlled by the constant speed and pressure pump 4, it is injected into the upstream opening of the reactor 29 through the constant speed and pressure pump discharge valve 6. The brine container 7, the first brine injection control valve 9, the second brine injection control valve 12, and the brine injection pump 11 are connected in sequence through the brine injection pipeline 10 and inject brine 8 into the reactor 29 through the upstream opening of the reactor body. The CO2 cylinder 1 is used to store CO2 gas. The constant speed and pressure pump 4 is used to control the flow rate and pressure of the injected gas. The brine container 7 is used to store brine 8. The brine injection pump 11 is used to control the flow rate and rate of brine 8 injection.

[0055] In this embodiment of the invention, the core reaction system includes a core support 27, a reaction vessel 29, a temperature and pressure sensor, a transmitting probe 35, and a receiving probe 36. The reaction vessel 29 is horizontally arranged on the upper end of the core support 27 and is used to contain a rock sample 32. A reaction vessel cover 28 is also provided at the inlet of the reaction vessel 29. The temperature and pressure sensor, the transmitting probe 35, and the receiving probe 36 are respectively installed inside the reaction vessel 29. The temperature and pressure sensor is electrically connected to the data analysis system 40. Figure 2 As shown, this is an enlarged schematic diagram of the rock sample area. The transmitting probe 35 and the receiving probe 36 are respectively arranged on the symmetrical sides of the rock sample 32. The transmitting probe 35 and the receiving probe 36 are electrically connected to the pulse measurement system. The reaction vessel 29 is connected to the fluid injection system and the drainage system respectively. The reaction vessel 29 is also connected to a vacuum pump 25 through the exhaust pipe 26.

[0056] The vacuum pump 25 is connected to the downstream opening of the reactor 29 via the suction pipe 26. The core support 27 is placed on the side of the reactor 29 to support its horizontal placement. The rock sample 32 is also geometrically horizontal. Multiple sets of transmitting probes 35 and receiving probes 36 are symmetrically arranged on the column of the rock sample 32. The temperature and pressure sensor 39 is placed inside the reactor 29 and electrically connected to the data analysis system 40. The core support 27 is used to horizontally place the reactor 29. The vacuum pump 25 is used to evacuate the experimental apparatus, such as the reactor 29. The reactor 29 is used to provide the experimental space. The temperature and pressure sensor is used to monitor and transmit data related to temperature and pressure during the experiment. The transmitting probe 35 is used to generate transient vibrations after being excited by a high-voltage electrical signal and propagates the vibrations in the rock sample 32 at a certain speed. The receiving probe 36 is used to receive the pulse signals propagated by the transmitting probe 35.

[0057] In this embodiment of the invention, the confining pressure system includes a confining pressure circulation pump 23, a hydraulic loading first control valve 22, a hydraulic loading second control valve 24, and a liquid storage container 19. The liquid storage container 19 is connected to the reactor 29 via a hydraulic oil line 21. The hydraulic oil line 21 is respectively equipped with the confining pressure circulation pump 23, the hydraulic loading first control valve 22, and the hydraulic loading second control valve 24. The hydraulic loading first control valve 22 is located between the confining pressure circulation pump 23 and the liquid storage container 19, and the hydraulic loading second control valve 24 is located between the confining pressure circulation pump 23 and the reactor 29.

[0058] The liquid storage container 19 is connected in sequence to the first hydraulic loading control valve 22, the confining pressure circulation pump 23, and the second hydraulic loading control valve 24 via the hydraulic oil pipeline 21, and is connected to the reactor 29 through the downstream opening of the reactor body; the confining pressure circulation pump 23 is used to apply confining pressure to the rock sample 32 to be tested; the liquid storage container 19 is used to store the liquid used for confining pressure loading.

[0059] In this embodiment of the invention, the back pressure system includes an oil tank 13, a back pressure oil injection first control valve 16, a back pressure oil injection second control valve 18, and a back pressure pump 17. The oil tank 13 is connected to the reactor 29 through a back pressure oil injection pipeline 15. The back pressure oil injection pipeline 15 is respectively equipped with a back pressure oil injection second control valve 18 and a back pressure pump 17.

[0060] The oil tank 13 is connected in sequence to the first back pressure oil injection control valve 16, the back pressure pump 17, and the second back pressure oil injection control valve 18 via the back pressure oil injection pipeline 15, and finally connected to the upstream opening of the reactor 29; the back pressure oil 14 tank 13 is used to store the back pressure oil 14 that provides back pressure; the back pressure pump 17 is used to pump the fluid from the low pressure area to the high pressure area to provide the back pressure required for the experiment.

[0061] In this embodiment of the invention, a temperature control system is provided on the outside of the reaction vessel 29. The temperature control system includes a heating plate 31 and a heat insulation cover 30. The heating plate 31 is disposed on the bottom surface of the reaction vessel 29, and the heat insulation cover 30 is arranged around the outside of the reaction vessel 29.

[0062] The heating plate 31 is located on the bottom downstream of the reactor 29 and is used to raise the temperature to the target value. The heat insulation cover 30 is arranged around the reactor 29. The heating plate 31 is used to provide the target temperature for the reaction. The heat insulation cover 30 is used to keep the equipment or environment within the required temperature range and reduce heat transfer and loss.

[0063] In this embodiment of the invention, the pulse measurement system includes a pulse generator 33, a preamplifier 37, and an oscilloscope 38. The pulse generator 33 is electrically connected to the transmitting probe 35 via a wire 34, and the oscilloscope 38, the preamplifier 37, and the receiving probe are electrically connected sequentially via the wire 34.

[0064] The pulse generator 33 emits a high-voltage pulse signal, which is transmitted to the rock sample 32 through the transmitting probe 35. Upon receiving the pulse signal from the transmitting probe 35, the rock sample 32 transmits the signal to the receiving probe 36, which then transmits the signal to the preamplifier 37 for amplification. The amplified signal is then transmitted to the oscilloscope 38, which displays the signal processed by the preamplifier 37. Figure 3 The diagram shows a waveform of an acoustic signal acquired by an oscilloscope. The pulse generator 33 is used to generate a pulse signal to excite the rock sample 32. The preamplifier 37 is used to initially amplify the weak signal received by the receiving probe 36. The oscilloscope 38 is used to display a real-time graph of the fluctuation.

[0065] In this embodiment of the invention, the drainage system includes a drainage pipeline 41, a drainage filter valve 42, a drainage control valve 43, and a waste liquid storage container 44. The waste liquid storage container 44 is connected to the reaction vessel 29 through the drainage pipeline 41. The drainage pipeline 41 is respectively equipped with a drainage filter valve 42 and a drainage control valve 43.

[0066] The drain line 41 is led out from the bottom of the downstream side of the reactor 29, and after the waste liquid is discharged through the drain filter valve 42 and the drain control valve 43, it is connected to the waste liquid storage container 44. The drain filter valve 42 is used to filter impurities in the waste liquid before discharge. The drain control valve 43 is used to control the flow rate and rate of waste liquid discharge. The waste liquid storage container 44 is used to hold the experimental waste liquid 45 discharged after the experiment.

[0067] In this embodiment of the invention, the data analysis system 40 has built-in data processing related programs and is connected to the oscilloscope 38 via a cable to collect and process pulse signals to obtain acoustic signal data, and to analyze and process other collected data to obtain quantitative assessment results of CO2 geological sequestration and salt precipitation in saline aquifers.

[0068] Specifically, in this embodiment of the invention, a high-resolution image of rock sample 32 is first captured using a micron-sized CT scanner to obtain first image data. After the rock sample 32 in the core reaction system is tested, a high-resolution image of the rock sample 32 after the test is captured using a micron-sized CT scanner to obtain second image data. The data analysis system 40 calculates the first volume of salt precipitated based on the acoustic signal data monitored in real time during the test. The data analysis system 40 extracts the first porosity of rock sample 32 before the test and the second porosity of rock sample 32 after the test based on the first and second image data, and calculates the difference to obtain the second volume of salt precipitated during the test. The error value is calculated based on the first and second volumes of salt precipitated, and it is confirmed whether the error value is within a preset threshold range to obtain a quantitative assessment result of CO2 geological sequestration salt precipitation in the saline aquifer.

[0069] Specifically, the data analysis system 40 extracts the first porosity of the rock sample 32 before the experiment and the second porosity of the rock sample 32 after the experiment based on the first image data and the second image data, and calculates the difference to obtain the second volume of salt precipitated during the experiment.

[0070] The empirical formula for determining the longitudinal wave velocity versus porosity is:

[0071] ;

[0072] In the formula, The P-wave velocity of the rock sample is 32, which is an indeterminate value that varies with time. , and It is a constant. Porosity This represents the clay content in the sample.

[0073] Before conducting the displacement experiment, the longitudinal wave velocity in the same batch of samples (at least 3) was measured. ), porosity ( and clay content ( ) These three parameters, calculate the parameters. , and .

[0074] The initial porosity and initial longitudinal wave velocity of the rock sample 32 selected for the displacement experiment are defined as follows: and And there are During the experiment, the longitudinal wave signal was continuously recorded. During the experiment t At any given time, based on the relationship between longitudinal wave velocity and porosity, we have: Then there is t Relationship between changes in longitudinal wave velocity and porosity at time and before the experiment:

[0075] ;

[0076] In the formula, for t The actual porosity of rock sample 32 at time point. for t The change in porosity of rock sample 32 at time of the experiment compared to the porosity of rock sample 32 before the experiment.

[0077] The saturated precipitated salt exists in the pore space of rock sample 32, which will reduce the rock porosity, defined as... t The volume of salt precipitated at time is ,have t The volume of salt precipitated at time and t The relationship between the change in porosity of rock sample 32 at different times:

[0078] ;

[0079] In the formula, This represents the actual pore volume in rock sample 32 before the experiment. For the experiment t Actual pore volume of rock sample 32 at time. This represents the total volume of rock sample 32.

[0080] Then we have:

[0081]

[0082] Define the salting-out rate S as t If the volume of salt precipitated at a given time is greater than the volume of rock sample 32, then...

[0083] ;

[0084] At the end of the experiment, that is Volume of salt precipitated at time :

[0085] ;

[0086] Salting out rate for:

[0087] ;

[0088] Porosity of rock sample 32 before extraction experiment and the porosity of rock sample 32 after the experiment. Calculate the second volume of salt precipitated during the experiment by taking the difference. .

[0089] First volume of precipitated salt measured based on acoustic pulse signal data. Second volume of salt extracted from CT images Whether the values ​​are consistent (within a preset threshold range of 10%) is used to determine whether the proposed longitudinal wave velocity-porosity formula is reasonable.

[0090] In this embodiment of the invention, the preset threshold range may be, for example, 10%, and the quantitative evaluation result of CO2 geological sequestration salting in the saline aquifer is used to characterize whether the currently determined P-wave velocity-porosity formula is reasonable.

[0091] The quantitative assessment device for CO2 geological sequestration salting out in saline aquifers described in this invention provides the experimental environment through a core reaction system, provides the required scCO2 and brine 8 through a fluid injection system, and provides acoustic signals to the rock samples through a pulse measurement system. The data analysis system 40 analyzes the collected data to obtain the quantitative assessment results of CO2 geological sequestration salting out in saline aquifers. This device can realistically simulate the salting out phenomenon induced by CO2 injection into saline aquifers, monitor the entire salting out process in real time, calculate the amount of salting out, and establish the correspondence between rock salting out amount, P-wave velocity, and porosity. This is of great significance for a deeper understanding of the salting out mechanism and for the prediction and control of salting out. It enables real-time non-destructive monitoring and calculation of salting out at the core scale, further revealing the salting out mechanism of CO2 geological sequestration in saline aquifers, and more accurately proposing methods and strategies to mitigate salting out. This provides a scientific basis for the injection process and sequestration safety of CO2 geological sequestration.

[0092] Based on the above embodiments, as a supplement to the above... Figure 1 The present invention provides an embodiment of a quantitative assessment method for CO2 geological sequestration and salt precipitation in saline aquifers, based on the implementation of the device shown. This method embodiment is similar to... Figure 1 The device embodiments shown correspond to the one described above. Figure 4 As shown, the quantitative assessment method for CO2 geological sequestration and salting out in saline aquifers includes the following steps:

[0093] S1: Weigh the clean and dry rock sample 32, and then use micron CT to take a high-resolution image of the rock sample 32 to obtain the first image data;

[0094] S2: The transmitting probe 35 and the receiving probe 36 are symmetrically arranged on both sides of the column of the rock sample 32, and then wrapped with polytetrafluoroethylene and aluminum foil from the inside to the outside and placed in a rubber sleeve to uniformly transfer the confining pressure. Then it is put into the reaction vessel 29, and the rock sample 32 is fixed by the pad block.

[0095] S3: Connect the fluid injection system, confining pressure system, back pressure system, and drainage system to the core reaction system respectively, and flush the corresponding pipelines with toluene, formaldehyde, and distilled water, and then dry them with nitrogen; and electrically connect the pulse measurement system and data analysis system 40 to the core reaction system respectively.

[0096] S4: Turn on the electric heating plate 31 to raise the temperature in the reactor 29 to the target value and stabilize it for 8 hours. Apply confining pressure to the rock sample 32 through the confining pressure system. Turn on the fluid injection system to inject gaseous CO2 into the rock sample 32 to remove the original air and water vapor in the pore space. Then use the vacuum pump 25 to evacuate the rock sample 32 for at least 24 hours to ensure that there is no air residue in the pore throat. When the vacuum pump 25 is working, turn off the fluid injection system and then turn on the back pressure system to apply back pressure to the rock sample 32.

[0097] S5: Open the fluid injection system to inject brine 8 into the rock sample 32 until the core sample reaches saturation. At the same time, open the drain filter valve 42 and the drain control valve 43 of the drain system to discharge the experimental waste liquid 45.

[0098] S6: Open the fluid injection system to increase CO2 to the target pressure, and then inject it into the reactor 29 at a constant rate in a supercritical phase. During the injection process, the waste liquid discharge system remains open.

[0099] S7: During the experiment in reactor 29, turn on temperature and pressure sensor 39, pulse generator 33, preamplifier 37 and oscilloscope 38 to monitor temperature data, pressure data and acoustic signal data during the experiment.

[0100] S8: After the reaction is complete, drain the fluid from the 32 pores of the rock sample, and then perform confining pressure unloading and cooling treatment;

[0101] S9: Take samples of the solid products attached to the surface of rock sample 32 for composition analysis;

[0102] S10: The data analysis system 40 processes and analyzes the acoustic signal data monitored in real time during the experiment, and calculates the first volume of salt precipitated.

[0103] S11: High-resolution images of rock sample 32 after the experiment were captured using micron-scale CT to obtain the second image data;

[0104] S12: Based on the first image data and the second image data of rock sample 32, extract the first porosity of rock sample 32 before the experiment and the second porosity of rock sample 32 after the experiment, and calculate the second volume of salt precipitated during the experiment by subtracting the first image data and the second image data of rock sample 32.

[0105] S13: Calculate the error value based on the first and second volumes of precipitated salt, and confirm whether the error value is within the preset threshold range to obtain the quantitative assessment result of CO2 geological sequestration salt precipitation in the saline aquifer.

[0106] The saline aquifer CO2 geological sequestration salt precipitation quantitative assessment device provided in the above embodiments can execute the saline aquifer CO2 geological sequestration salt precipitation quantitative assessment method described in the embodiments of the present invention. The saline aquifer CO2 geological sequestration salt precipitation quantitative assessment method has the corresponding functional components and beneficial effects of the saline aquifer CO2 geological sequestration salt precipitation quantitative assessment device described in the above embodiments. For details, please refer to the embodiments of the saline aquifer CO2 geological sequestration salt precipitation quantitative assessment device described above. The embodiments of the present invention will not be repeated here.

[0107] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

Claims

1. A device for quantitatively assessing CO2 sequestration and salt precipitation in saline aquifers, characterized in that, The quantitative assessment device for CO2 geological sequestration and salting-out in saline aquifers includes: The system includes a fluid injection system, a core reaction system, a confining pressure system, a back pressure system, a pulse measurement system, a drainage system, and a data analysis system; the fluid injection system, confining pressure system, back pressure system, and drainage system are all connected to the core reaction system, and the pulse measurement system and data analysis system are all electrically connected to the core reaction system. The fluid injection system is used to inject fluid into the core reaction system, the fluid including CO2 and brine; The core reaction system provides an experimental environment for reaction experiments on rock samples. The confining pressure system is used to apply confining pressure to the rock sample in the core reaction system; The back pressure system is used to provide back pressure for the core reaction system; The pulse measurement system is used to generate a pulse signal that excites the rock sample and to receive the received signal after it passes through the rock sample; The drainage system is used to receive the fluid waste liquid discharged from the core reaction system; The data analysis system is used to collect and analyze the data from the core reaction system reaction experiment to obtain quantitative assessment results of CO2 geological sequestration and salting out of the saline aquifer. The data analysis system is used to acquire and process pulse signals to obtain acoustic signal data, calculate the first volume of precipitated salt based on the acoustic signal data monitored in real time during the experiment, and extract the first porosity of the rock sample before the experiment based on the first and second image data of the rock sample. and the second porosity of the rock sample after the experiment The second volume of salt precipitated during the experiment was obtained by subtraction. The first image data and the second image data are high-resolution images of the rock sample before and after the experiment, respectively; and based on the first volume of precipitated salt... and the second volume The error value is calculated, and it is confirmed whether the error value is within a preset threshold range to obtain the quantitative assessment result of CO2 geological sequestration and salting out of the saline aquifer. The preset threshold range for the error value is 10%. The empirical formula for determining the longitudinal wave velocity versus porosity is: ； In the formula, The longitudinal wave velocity of the rock sample is an indeterminate value that varies with time. , and It is a constant. Porosity The clay content in the rock sample; The initial porosity and initial P-wave velocity of the rock samples selected for the displacement experiment are defined as follows: and And there are During the experiment, the longitudinal wave signal was continuously recorded. During the experiment t At any given time, based on the relationship between longitudinal wave velocity and porosity, we have: Then there is t Relationship between changes in longitudinal wave velocity and porosity at time and before the experiment: ； In the formula, for t The actual porosity of the rock sample at any given time. for t The change in porosity of the rock sample at a given time compared to the porosity of the rock sample before the experiment; definition t The volume of salt precipitated at time is ,have t The volume of salt precipitated at each time and t The relationship between the change in porosity of rock samples over time: ； In the formula, This represents the actual pore volume in the rock sample before the experiment. For the experiment t The actual pore volume of the rock sample at any given time. This represents the total volume of the rock sample. Then we have: ； At the end of the experiment, that is The volume of salt precipitated at that time : 。 2. The quantitative assessment device for CO2 geological sequestration and salt precipitation in saline aquifers according to claim 1, characterized in that: The fluid injection system includes a CO2 cylinder, a brine container, a constant-speed and constant-pressure pump, and a brine injection pump. The CO2 cylinder is connected to the core reaction system via a CO2 injection pipeline, and the CO2 injection pipeline is equipped with a CO2 injection control valve and a constant-speed and constant-pressure pump. The brine container is connected to the core reaction system via a brine injection pipeline, and the brine injection pipeline is equipped with a brine injection pump, a first brine injection control valve, and a second brine injection control valve. The first brine injection control valve is located between the brine container and the brine injection pump, and the second brine injection control valve is located between the brine injection pump and the core reaction system.

3. The quantitative assessment device for CO2 geological sequestration and salt precipitation in saline aquifers according to claim 1, characterized in that: The core reaction system includes a core support, a reaction vessel, a temperature and pressure sensor, a transmitting probe, and a receiving probe. The reaction vessel is horizontally positioned on the upper end of the core support and is used to contain the rock sample. The temperature and pressure sensor, the transmitting probe, and the receiving probe are respectively installed inside the reaction vessel. The temperature and pressure sensor is electrically connected to the data analysis system. The transmitting probe and the receiving probe are respectively located on symmetrical sides of the rock sample and are electrically connected to the pulse measurement system. The reaction vessel is connected to the fluid injection system and the drainage system.

4. The quantitative assessment device for CO2 geological sequestration and salt precipitation in saline aquifers according to claim 3, characterized in that: The reactor is also connected to a vacuum pump via an extraction pipe.

5. The quantitative assessment device for CO2 geological sequestration and salt precipitation in saline aquifers according to claim 3, characterized in that: The confining pressure system includes a confining pressure circulation pump, a first hydraulic loading control valve, a second hydraulic loading control valve, and a liquid storage container. The liquid storage container is connected to the reactor via a hydraulic oil pipeline. The hydraulic oil pipeline is respectively equipped with the confining pressure circulation pump, the first hydraulic loading control valve, and the second hydraulic loading control valve. The first hydraulic loading control valve is located between the confining pressure circulation pump and the liquid storage container, and the second hydraulic loading control valve is located between the confining pressure circulation pump and the reactor.

6. The quantitative assessment device for CO2 geological sequestration and salt precipitation in saline aquifers according to claim 3, characterized in that: The back pressure system includes an oil tank, a first back pressure oil injection control valve, a second back pressure oil injection control valve, and a back pressure pump. The oil tank is connected to the reactor through a back pressure oil injection pipeline, and the second back pressure oil injection control valve and the back pressure pump are respectively installed on the back pressure oil injection pipeline.

7. The quantitative assessment device for CO2 geological sequestration and salt precipitation in saline aquifers according to claim 3, characterized in that: A temperature control system is provided on the outside of the reactor. The temperature control system includes a heating plate and a heat insulation cover. The heating plate is located on the bottom surface of the reactor, and the heat insulation cover is arranged around the outside of the reactor.

8. The quantitative assessment device for CO2 geological sequestration and salt precipitation in saline aquifers according to claim 3, characterized in that: The pulse measurement system includes a pulse generator, a preamplifier, and an oscilloscope. The pulse generator is electrically connected to the transmitting probe via a wire, and the oscilloscope, the preamplifier, and the receiving probe are electrically connected in sequence via wires.

9. The quantitative assessment device for CO2 geological sequestration and salt precipitation in saline aquifers according to claim 3, characterized in that: The drainage system includes a drainage pipeline, a drainage filter valve, a drainage control valve, and a waste liquid storage container. The waste liquid storage container is connected to the reaction vessel through the drainage pipeline, and the drainage pipeline is equipped with a drainage filter valve and a drainage control valve.

10. A method for quantitatively assessing CO2 geological sequestration and salt precipitation in saline aquifers, using the quantitative assessment device for CO2 geological sequestration and salt precipitation in saline aquifers as described in any one of claims 1-9, characterized in that, Includes the following steps: S1: Weigh the clean and dry rock sample, and then use micron CT to take a high-resolution image of the rock sample to obtain the first image data; S2: The transmitting probe and the receiving probe are symmetrically arranged on both sides of the column of the rock sample, and then wrapped with polytetrafluoroethylene and aluminum foil from the inside to the outside and placed in a rubber sleeve to uniformly transfer the confining pressure. Then it is put into the reaction vessel, and the rock sample is fixed by the pad block. S3: Connect the fluid injection system, confining pressure system, back pressure system, and drainage system to the core reaction system respectively. The corresponding pipelines are flushed with toluene, formaldehyde, and distilled water, and then dried with nitrogen. Connect the pulse measurement system and data analysis system to the core reaction system respectively. S4: Turn on the electric heating plate to raise the temperature in the reactor to the target value and stabilize it for 8 hours. Apply confining pressure to the rock sample through the confining pressure system. Turn on the fluid injection system to inject gaseous CO2 into the rock sample to remove the original air and water vapor in the pore space. Then use a vacuum pump to evacuate the rock sample for at least 24 hours to ensure that there is no air residue in the pore throat. When the vacuum pump is working, turn off the fluid injection system and then turn on the back pressure system to apply back pressure to the rock sample. S5: Open the fluid injection system to inject brine into the rock sample until the core sample reaches saturation. At the same time, open the drain filter valve and drain control valve of the drain system to discharge the experimental waste liquid. S6: Open the fluid injection system to increase CO2 to the target pressure, and then inject it into the reactor at a constant rate in a supercritical phase. During the injection process, the waste liquid discharge system remains open. S7: During the reactor experiment, turn on the temperature and pressure sensors, pulse generator, preamplifier and oscilloscope to monitor the temperature data, pressure data and acoustic signal data during the experiment. S8: After the reaction is complete, drain the pore fluid from the rock sample, and then perform confining pressure unloading and cooling treatment. S9: Take samples of solid products attached to the surface of rock samples for composition analysis; S10: The data analysis system processes and analyzes the acoustic signal data monitored in real time during the experiment, and calculates the first volume of salt precipitated. S11: High-resolution images of the rock samples after the experiment were captured using micron-CT to obtain the second image data; S12: Based on the first and second image data of the rock sample, extract the first porosity of the rock sample before the experiment and the second porosity of the rock sample after the experiment, and calculate the second volume of salt precipitated during the experiment by subtracting the first image data and the second image data of the rock sample after the experiment. S13: Calculate the error value based on the first and second volumes of precipitated salt, and confirm whether the error value is within the preset threshold range to obtain the quantitative assessment result of CO2 geological sequestration salt precipitation in the saline aquifer.

Images