A method and injection system for CO2 microbubble enhanced geological mineralization sequestration

Abstract

The present application relates to a kind of CO2 Microbubble Reinforced Geological Mineralization Sequestration Method and injection system, belong to CO2 geological sequestration and CCUS technical field.Adding the chemical foaming agent for generating or stabilizing bubble, surfactant or nanomaterial under the condition of not, gaseous or supercritical state CO2 With formation water or simulated brine is introduced into injection system respectively, pre-dispersion is formed by mechanical stirring gas-liquid mixed flow, and metastable CO2 Microbubble is generated by multistage micropore shear processing, and it is made into core or target reservoir before significant coalescence by low delay delivery mode.Utilize the specific surface area, interface additional pressure and small size characteristics of CO2 Microbubble, improve CO2 To pore water mass transfer and dissolution efficiency, expand CO2-water-rock contact range, promote reservoir mineral dissolution and carbonate mineral precipitation.The present application can avoid reservoir damage caused by exogenous chemical agent, and is expected to improve CO2 Mineralization capture efficiency and sequestration stability.

Description

Technical Field

[0001] This invention belongs to the field of CO2 geological storage and CCUS technology, and in particular relates to a CO2 geological storage enhanced mineralization capture method and injection system based on pure physical microbubble generation and online injection. Background Technology

[0002] CO2 geological sequestration is one of the key technologies for addressing climate change. Among various geological types, deep saline aquifers have attracted significant attention due to their wide distribution and enormous sequestration potential. In particular, CO2 mineralization sequestration, which involves converting gaseous or supercritical CO2 into thermodynamically stable solid carbonate minerals (such as calcite and dolomite) through the physicochemical interaction of CO2, saline aquifers, and rocks, is considered the safest and most permanent form of sequestration because it significantly reduces the risk of long-term CO2 leakage. However, in the practical engineering application of deep saline aquifer mineralization sequestration, key scientific and technological challenges remain that limit sequestration efficiency and safety.

[0003] First, the physicochemical properties of traditional injection fluids limit CO2 sweep efficiency and reaction rate. Currently, the mainstream injection media are supercritical CO2 or saturated carbonated water. Supercritical CO2 has a viscosity much lower than that of saline water, making it highly susceptible to viscous fingering and gravity overlap in saline layers. This results in the fluid preferentially rushing along high-permeability channels, leaving vast low-permeability matrix areas untouched. This heterogeneous flow not only significantly reduces the effective utilization volume of the reservoir but also results in extremely limited contact area between CO2 and rock minerals. While saturated carbonated water flooding improves acidic contact, it is limited by the solubility constraints of Henry's Law. The dissolution and mass transfer efficiency of CO2 in saline water is slow, and the fluid still tends to flow along dominant channels, making it difficult to penetrate the micron- or even submicron-sized dense matrix pores. This leads to extremely slow deep mineralization reaction kinetics and an extremely long mineralization reaction cycle.

[0004] Secondly, existing chemical foam fluid technology carries the dual risks of cost and reservoir damage. To address fluid mobility control, current technologies often employ CO2 foam fluids for displacement. This involves adding surfactants to the liquid phase and utilizing the Jamin effect of the foam fluid to block dominant channels. However, this method has significant drawbacks: maintaining foam stability requires high concentrations of chemical agents, significantly increasing the operating costs of storage projects; moreover, these chemicals are easily adsorbed onto the reservoir rock surface, causing losses; most importantly, most foaming agents are amphiphilic molecules, potentially altering rock surface wettability or reacting with reservoir-sensitive minerals, thereby inducing clay swelling or migration, leading to irreversible damage to reservoir permeability.

[0005] Secondly, emerging nanomaterial-based bubble stabilization technologies face challenges related to solid-phase blockage and process complexity. In recent years, some studies have proposed using modified nanomaterials to construct Pickering emulsions or ultrastable nanobubbles to improve bubble stability. While solid particles can build stable bubble walls, introducing them into deep reservoirs introduces new risks: nanomaterials are prone to mechanical blockage at fine throats, causing physical blockage in the near-wellbore zone or deep matrix, severely impairing injection capacity. Furthermore, the preparation process of nanomaterials is complex, and dispersion stability is difficult to control, making it difficult to meet the demands of large-scale industrial injection.

[0006] In summary, existing geological sequestration technologies face a dilemma: traditional injection methods result in poor reach and slow reaction times; the use of chemical agents or nanomaterials leads to soaring sequestration operation costs and damages the formation. Based on existing theories, microbubbles possess unique physicochemical advantages: First, the microbubble particle size is lower than or close to the pore radius of the rock matrix, allowing it to enter tiny pores that are difficult for conventional fluids to reach in a dispersed phase form; second, the smaller the bubble size, the higher the internal pressure, and the high internal pressure of microbubbles can significantly enhance the dissolution driving force of gas in the liquid phase, strengthening mass transfer; third, under the same volume conditions, the gas-liquid contact area of ​​microbubbles is orders of magnitude larger than that of macrobubbles, greatly accelerating geochemical reaction processes.

[0007] However, most existing physical microbubble generators are designed for atmospheric or low-pressure environments. Under the temperature and pressure conditions of deep saline aquifers, gas properties change drastically, and the shear efficiency of traditional physical generators drops sharply, making it difficult to generate microbubbles with a narrow particle size range. Secondly, without chemical agents, purely physical microbubble preparation is a thermodynamically unstable system. During the long-distance wellbore or pipeline transport to the formation using existing surface injection processes, microbubbles rapidly break down and merge due to maturation or collision aggregation, ultimately entering the formation as a stratified gas-liquid fluid, losing the advantages of microbubble scale. Thirdly, existing general-purpose bubble generators typically prioritize high throughput, making it difficult to precisely control bubble size distribution. If the bubble size cannot form an excellent match with the porosity of the sandstone matrix, a severe Jamin effect can easily occur, leading to injection difficulties.

[0008] In summary, how to reconstruct the fluid phase state at the micropore scale using purely physical methods, and how to utilize the "transient" high-energy characteristics of microbubbles to achieve homogenization and enhanced mineralization capture efficiency in deep saline water layers, are the technical bottlenecks that urgently need to be overcome in the current CCUS field. Summary of the Invention

[0009] The purpose of this invention is to provide: A CO2 microbubble-enhanced geological mineralization storage method and injection system are proposed to address the problems of slow CO2 mass transfer rate, limited CO2-water-rock reaction range, low mineralization capture efficiency, and potential reservoir damage, increased costs, and reduced injection capacity caused by auxiliary methods such as chemical foaming agents or nano-stabilizers in traditional CO2 storage.

[0010] Terminology Explanation: Unless otherwise defined, all technical terms herein have the same meaning as commonly understood by one of ordinary skill in the art to which this subject matter pertains.

[0011] The terms “optional / arbitrary” or “optionally / arbitrarily” mean that the event or situation described below may or may not occur, including both the occurrence and non-occurrence of the event or situation.

[0012] The term "CO2 microbubbles" used in this article refers to: microbubbles with diameters typically in the micrometer range (1-100 μm), preferably d... 50 Metastable dispersion system formed by carbon dioxide microbubbles with a particle size of 5-20 μm dispersed in an aqueous phase. The metastable state refers to the fact that CO2 microbubbles can maintain a dispersed state for a limited time without the addition of chemical foaming agents, surfactants or nanomaterial stabilizers, but may become unstable due to ripening, collision or agglomeration. Therefore, it is necessary to inject them into the core or target reservoir through a low-delay connection pipeline before they significantly agglomerate.

[0013] The term "coalescing half-life" used in this article refers to the change in the amount of CO2 dispersed phase over time using a high-pressure visualization unit under the same temperature, pressure, and mineralization conditions as the injection process. The time corresponding to when the amount of identifiable CO2 dispersed phase in a unit field of view at the start of observation is N0, and the time when the amount of identifiable CO2 dispersed phase in a unit field of view decreases to 0.5N0, is defined as the coalescing half-life.

[0014] The term "purely physical generation" as used in this article refers to the generation of CO2 microbubbles through physical means such as mechanical stirring or mechanical shearing, without the addition of chemical foaming agents, surfactants, or nano-stabilizers.

[0015] The term "low-delay injection" as used in this paper refers to shortening the transport path and time of CO2 microbubbles from the generation outlet of the multi-stage microporous shear unit to the inlet of the porous medium, allowing the CO2 microbubble fluid to enter the core or target reservoir before significant coalescence or gas-liquid stratification occurs. Low-delay injection does not mean that the transport time is absolutely zero. Under core-scale injection and evaluation conditions, the transport path can be formed by low-delay connecting pipelines, and the transport time is preferably no more than 10 s. Under target reservoir application conditions, low-delay injection can be achieved by setting the CO2 microbubble generation unit at the wellhead, wellbore, adjacent location, or downhole, and shortening the transport distance from it to the inlet of the target layer.

[0016] The volume ratio of CO2 to formation water or simulated saline water mentioned in this article refers to the volume flow ratio of the two under the system's operating temperature and pressure conditions; the volume flow rate entering the porous ceramic membrane or sintered metal medium mentioned in this article refers to the total apparent volume flow rate of the gas-liquid mixture formed by CO2 and the water phase.

[0017] The term “mineralization capture” as used in this article refers to the CCUS core pathway that converts gaseous CO2 into stable carbonate minerals for permanent sequestration.

[0018] In a first aspect, the present invention provides: A CO2 microbubble-enhanced geological mineralization sequestration method includes: S1. Without adding chemical foaming agents, surfactants, or nano-stabilizers, introduce gaseous or supercritical CO2 and simulated saline water or formation water into the injection system, and set the injection pressure P. inj , so that its P pore <P inj <P frac , where P pore For the target saline aquifer pore pressure, P frac The target saline aquifer rock fracture pressure; S2. The aqueous phase and gaseous or supercritical CO2 are mixed and mechanically stirred for pre-dispersion treatment to form a strong turbulent shear field in the fluid, reconstructing the discontinuous gas slugs into agglomerate flow, forming a pre-dispersed gas-liquid mixed flow. S3. The water and CO2 mixture is subjected to multi-stage microporous shearing treatment, which is carried out step by step through stainless steel wire mesh, porous ceramic membrane plate or sintered metal medium to generate metastable CO2 microbubble fluid. S4. The metastable CO2 microbubble fluid is transported and injected into the core or target reservoir before significant aggregation or gas-liquid stratification, so that the CO2 microbubbles enter the porous medium while maintaining a dispersed state. S5. Under the target reservoir temperature and pressure conditions, the CO2 microbubbles are brought into contact with pore water and reservoir minerals to increase the mass transfer rate of CO2 to pore water and expand the CO2-water-rock contact range.

[0019] Furthermore, the mechanical stirring pre-dispersion treatment involves a stirring speed of 2000-6000 rpm, and a stirring Reynolds number of [missing information]. Re >10 4 This creates a strong turbulent shear field in the gas-liquid mixture, reforming the discontinuous slug flow into a clump flow.

[0020] Furthermore, in step S4, the microbubble fluid is injected using a pulsed injection method: Microbubble fluid generated by S3 and simulated saline water were alternately injected into the core.

[0021] Furthermore, the volume of a single injection of CO2 microbubble fluid is 0.2-0.5 PV; The volume of simulated saline water injected in a single injection is set to 0.3-1.0 PV; and the volume of simulated saline water injected in a single injection must always be higher than the volume of CO2 microbubble fluid injected in a single injection.

[0022] Secondly, the present invention provides: A CO2 microbubble-enhanced geological mineralization injection system for implementing the above method includes: The fluid injection unit is used to simultaneously inject gaseous or supercritical CO2 and simulated saline water according to a set ratio. A mechanical stirring pre-dispersion unit, which is connected to a fluid injection unit, is used to stir the injected gaseous or supercritical CO2 and simulated saline water to perform preliminary mixing of CO2 and simulated saline water; A multi-stage microporous shearing unit, connected to the mechanical stirring and pre-dispersion unit, is used to perform stepwise microporous shearing on the initially mixed fluid to form metastable CO2 microbubbles. An online monitoring unit is connected to the outlet of the multi-stage microporous shearing unit and is used to observe the particle size distribution and dispersion state of the micron-sized CO2 dispersed phase online. The core displacement unit is connected to the outlet of the online monitoring unit via a low-delay connection pipeline, and is used to hold the core and receive the micron-sized CO2 dispersed phase fluid after online monitoring. A back pressure control unit, which is connected to the core displacement unit, is used to control the core outlet pressure.

[0023] Furthermore, the set ratio is set as follows: The permeability of the saline aquifer satisfies 1 mD ≤ K < 10 mD, and the volume ratio of CO2 to simulated saline aquifer is 1:20 to 1:5. The permeability of the saline aquifer satisfies 10 mD ≤ K < 50 mD, and the volume ratio of CO2 to simulated saline aquifer is 1:5 to 1:2. The permeability of the saline aquifer satisfies K ≥ 50 mD, and the volume ratio of CO2 to simulated saline water is 1:2 to 1:1.

[0024] Furthermore, the mechanical stirring and pre-dispersion unit includes a container, a motor is installed on the top of the container, a central shaft is installed inside the container, and the motor drives the central shaft to rotate; multiple layers of stirring blades are installed on the central shaft, and multiple baffles are vertically arranged on the inner wall of the container.

[0025] Furthermore, the outer diameter of the stirring blade is 1 / 3 to 1 / 2 of the inner diameter of the container.

[0026] Furthermore, the multi-stage microporous shearing unit includes a horizontal tubular shell, inside which a first stainless steel wire mesh, a second stainless steel wire mesh, and a porous ceramic membrane plate are arranged sequentially according to the liquid flow direction. The first stainless steel wire mesh has a mesh count of 100-300 mesh, the second stainless steel wire mesh has a mesh count of 2000-3000 mesh, and the porous ceramic membrane plate has an average pore size of 2-5 μm.

[0027] Furthermore, the tail of the horizontal tubular outer shell has a tapered contraction structure.

[0028] Furthermore, the volumetric flow rate of the gas-liquid mixture formed by CO2 and the aqueous phase entering the porous ceramic membrane or sintered metal medium is controlled at 5-10 mL / min under the system's operating temperature and pressure conditions. This flow rate range can create sufficient pressure difference, throttling expansion effect, and pore wall shearing effect within the microchannels, causing coarse-sized bubbles in the pre-dispersed fluid to be further broken down into micron-sized CO2 microbubbles. If the flow rate is too low, the bubbles are prone to coalesce at the outlet of the porous ceramic membrane to form large bubbles; if the flow rate is too high, it is easy to cause sedimentation at the core end face, resulting in an excessively high end face pressure difference.

[0029] Furthermore, the CO2 geological sequestration enhanced mineralization capture and injection system also includes: An online monitoring unit is installed between the multi-stage micropore shearing unit and the core displacement unit to monitor the fluid after micropore shearing online.

[0030] The online monitoring unit can also communicate with a monitoring computer and automatic control system to identify the particle size distribution, number density, and gas-liquid stratification of CO2 microbubbles. When CO2 microbubbles are detected... 50 When the CO2 microbubbles are >20 μm or when water and CO2 are clearly separated, under the condition that the injection pressure is lower than the target reservoir rock fracturing pressure and does not exceed the equipment's rated operating pressure, the automatic control system increases the stirring speed of the mechanical stirring pre-dispersion unit and / or increases the volumetric flow rate of the fluid entering the porous ceramic membrane plate or sintered metal medium, so as to enhance the turbulence intensity and pore wall shear stress until the CO2 microbubbles are restored to the micron-level dispersion state.

[0031] Furthermore, the online monitoring unit includes a metal casing with openings on both the upper and lower surfaces. An upper sapphire glass is disposed within the opening on the upper surface, and a lower sapphire glass is disposed within the opening on the lower surface. A microfluidic flow channel is provided between the upper and lower sapphire glass.

[0032] Furthermore, the outlet of the multi-stage microporous shearing unit and the inlet of the core displacement unit are connected by a low-delay connection pipeline, which is a high-pressure resistant capillary with an inner diameter of 0.25-1 mm and a length of 5-20 cm.

[0033] The present invention has at least the following beneficial effects: (1) It is expected to improve CO2 mineralization capture efficiency and storage stability.

[0034] This invention generates CO2 microbubble fluid through mechanical stirring pre-dispersion treatment and subsequent microporous shearing treatment. The microbubbles promote the formation of a high-concentration carbonic acid environment in pore water, enhance the CO2-water-rock reaction, and promote the Ca2+-carbon dioxide reaction. 2+ Mg 2+ Fe 2+ Plasma release and the provision of favorable conditions for carbonate mineral precipitation are expected to improve CO2 mineralization capture efficiency and storage stability.

[0035] (2) The unique physicochemical properties of microbubbles can be used to significantly enhance mass transfer kinetics and mineralization reaction rate.

[0036] Based on the Young-Laplace equation, the microbubbles prepared in this invention exhibit a significant surface tension self-pressurization effect (the smaller the bubble size, the higher the internal pressure). This high internal pressure mechanism provides an additional thermodynamic driving force for the mass transfer of CO2 to the aqueous phase. Based on the Young-Laplace effect, additional pressure is generated at the microbubble interface, increasing the local dissolution driving force of CO2 at the gas-liquid interface. Combined with the high specific surface area of ​​the CO2 microbubbles, this promotes the mass transfer and dissolution of CO2 to the aqueous phase, forming a relatively high concentration of carbonic acid within the pores. Compared to conventional macrofluids, this mechanism is expected to accelerate the dissolution rate of silicate minerals such as feldspar, which is beneficial for shortening the reaction cycle of mineralization and storage.

[0037] (3) To achieve effective sweep and modification of micropores in dense matrix.

[0038] This invention controls the microbubble particle size to match the pore throat size of the target reservoir, reducing interfacial blockage and additional capillary resistance caused by bubble sizes larger than the pore throat, thereby enhancing the entry and sweep capacity of CO2 microbubble fluid into tiny pores. This not only helps to increase the effective CO2 storage volume but also extends the chemical reaction field of CO2-saline water-rock to the microscopic inner surface of the rock.

[0039] (4) Provides a technical path for low-delay injection and engineering scale-up of pure physical CO2 microbubbles.

[0040] This invention combines mechanical stirring pre-dispersion, multi-stage microporous shearing, and low-delay transport to form CO2 microbubbles from CO2 and aqueous phase without the addition of chemical foaming agents, surfactants, or nano-stabilizers for bubble generation or stabilization. It also shortens the external transport time between the generation of these CO2 microbubbles and their entry into the porous medium. At the core scale, the residence of microbubbles outside the core can be reduced through low-delay connection pipelines. In target reservoir applications, the transport path from microbubbles to the target layer can be shortened by increasing the processing capacity of the microbubble generation equipment, using multiple shearing modules in parallel, and placing the microbubble generation unit at the wellhead, near the wellbore, or downhole. This provides a feasible technical solution for the engineering injection and scale-up of purely physical CO2 microbubbles. Attached Figure Description

[0041] Figure 1 This is a flowchart of the overall process flow of the system of the present invention; Figure 2 This is a cross-sectional view of the internal structure of the mechanical stirring pre-dispersion unit; Figure 3 This is a cross-sectional view of the internal structure of a multi-stage microporous shearing unit; Figure 4 This is a schematic diagram of the online monitoring components for visualization. Figure 5 This is a schematic diagram illustrating the transport mechanism of conventional large bubbles and CO2 microbubbles in the tiny pores of the reservoir. Figure 5 (a) represents the mechanism of localized retention of conventional large air bubbles due to pore throat limitation. Figure 5 (b) represents the mechanism by which CO2 microbubbles disperse into the pore channels along with the aqueous phase and expand their reach.

[0042] Explanation of reference numerals in the attached figures: 1 is a simulated saline water storage tank; 2 is a high-pressure injection pump; 3 is a CO2 gas cylinder; 4 is a first pressure sensor; 5 is a high-pressure gas booster pump; 6 is a high-pressure gas flow controller; 7 is a mechanical stirring and pre-dispersion unit; 8 is a second pressure sensor; 9 is a multi-stage microporous shearing unit; 10 is a visual online monitoring component; 11 is an optical microscope; 12 is a third pressure sensor; 13 is a core holder; 14 is a high-temperature constant temperature chamber; 15 is a confining pressure control pump; 16 is a fourth pressure sensor; 17 is a back pressure valve; and 18 is a liquid receiving device. 19 is a measuring cylinder; 20 is a monitoring computer; 21 is a baffle plate; 22 is a stirring impeller; 23 is the container wall; 24 is the inlet of the multi-stage microporous shearing unit; 25 is the first stainless steel wire mesh; 26 is the second stainless steel wire mesh; 27 is the porous ceramic membrane plate; 28 is the outlet of the multi-stage microporous shearing unit; 29 is the inlet of the high-pressure microfluidic flow cell; 30 is the upper sapphire glass; 31 is the lower sapphire glass; 32 is a high-magnification optical microscope; 33 is the microfluidic flow channel; 34 is the metal shell; 35 is the outlet of the high-pressure microfluidic flow cell. Detailed Implementation

[0043] The following non-limiting embodiments are intended to enable those skilled in the art to gain a more comprehensive understanding of the present invention, but do not limit the invention in any way. The following content is merely an exemplary description of the scope of protection claimed by the present invention, and those skilled in the art can make various changes and modifications to the present invention based on the disclosed content, and such changes should also fall within the scope of protection claimed by the present invention.

[0044] The present invention will be further described below by way of specific embodiments. Unless otherwise specified, all instruments, devices, equipment and other items used in the embodiments of the present invention are obtained through conventional commercial means.

[0045] Example 1 This embodiment provides a CO2 microbubble-enhanced geological mineralization preservation method, including: S1. Introduce CO2 and simulated saline water or formation water into the injection system without adding chemical foaming agents, surfactants or nano stabilizers.

[0046] S2. The aqueous phase and gaseous or supercritical CO2 are mixed and mechanically stirred for pre-dispersion treatment to form a preliminarily dispersed gas-liquid mixture; the stirring speed for mechanical pre-dispersion treatment is 2000-6000 rpm. The ratio of simulated saline water to CO2 is set as follows: When the permeability of the saline aquifer satisfies 1 mD ≤ K < 10 mD, the volume ratio of CO2 to simulated saline water is 1:20 to 1:5. The permeability of the saline aquifer satisfies 10 mD ≤ K < 50 mD, and the volume ratio of CO2 to simulated saline aquifer is 1:5 to 1:2. When the permeability of the saline aquifer meets K ≥ 50 mD, the volume ratio of CO2 to simulated saline water is 1:2 to 1:1.

[0047] S3. The gas-liquid mixture is subjected to multi-stage microporous shearing treatment, which is carried out step by step through stainless steel wire mesh, porous ceramic membrane plate or sintered metal medium to generate CO2 microbubble fluid.

[0048] S4. Inject the CO2 microbubbles generated in step S3 into the core or target reservoir through a low-delay pipeline or a low-delay connecting pipeline. As a preferred embodiment, the microbubble fluid is injected in a pulsed manner: the microbubble fluid generated in S3 and simulated saline water are injected alternately into the core.

[0049] The volume of CO2 microbubble fluid injected in a single injection is 0.2-0.5 PV. The volume of simulated saline water injected in a single injection is set to 0.3-1.0 PV; and the volume of simulated saline water injected in a single injection must always be higher than the volume of CO2 microbubble fluid injected in a single injection.

[0050] S5. Utilizing the high specific surface area, surface tension self-pressurization effect, and small size of CO2 microbubbles to enter the pore throat, the mass transfer and dissolution of CO2 into pore water is enhanced, creating a high-concentration carbonic acid environment within the pores, promoting the dissolution of reservoir minerals and releasing Ca. 2+ Mg 2+ Fe 2+ The presence of metal ions provides favorable conditions for the precipitation of carbonate minerals, and is expected to improve CO2 mineralization capture efficiency.

[0051] When the method of the present invention is used for a target reservoir, the mechanical stirring pre-dispersion unit and the multi-stage microporous shearing unit can be set at the wellhead, near the wellbore, or downhole. The injection flow rate and slug volume are determined according to the target layer’s liquid absorption capacity, wellbore structure, and allowable injection pressure, so that the generated CO2 microbubbles can enter the target layer while maintaining a dispersed state.

[0052] Example 2 A CO2 microbubble-enhanced geological mineralization injection system is provided to implement the CO2 microbubble-enhanced geological mineralization preservation method described in Example 1, such as... Figure 1 As shown, it includes: a fluid injection unit, a mechanical stirring and pre-dispersion unit 7, a multi-stage microporous shearing unit 9, an online monitoring unit, a core displacement unit, and a back pressure control unit.

[0053] The fluid injection unit includes a simulated saline water storage tank 1, a high-pressure injection pump 2, a CO2 cylinder 3, a high-pressure gas flow controller 6, and a high-pressure gas booster pump 5. The simulated saline water storage tank 1 is connected to the high-pressure injection pump 2, and the CO2 cylinder 3 is connected to the high-pressure gas booster pump 5 and the high-pressure gas flow controller 6. The flow rate of the simulated saline water is controlled by the high-pressure injection pump 2, and the flow rate of the CO2 is controlled by the high-pressure gas flow controller 6. Furthermore, in this invention, the simulated saline water storage tank 1 does not contain any surfactants, foaming agents, or nanomaterials; it only contains inorganic salt components commonly found in formation water.

[0054] Both the high-pressure injection pump 2 and the high-pressure gas flow controller 6 are connected to the mechanical stirring and pre-dispersion unit 7. The mechanical stirring and pre-dispersion unit 7 is a vertical high-pressure vessel with a volume of 1 L. For example... Figure 2 As shown, the vertical high-pressure vessel is driven by a top motor to rotate the central shaft. Multi-layer turbine-type stirring blades 21 are installed on the central shaft. Multiple baffles 20 are vertically arranged on the inner wall of the vessel wall 22. During the process of the stirring blades 21 rotating and driving the fluid flow, the fluid encounters the baffles 20. The baffles 20 generate shear force on the fluid, thereby destroying the fluid vortex through strong mechanical shearing, preventing CO2 and salt water from centrifugally separating due to density differences, and forcibly mixing CO2 and salt water into a clump flow or a fine bubble flow.

[0055] The outer diameter of the stirring blade 21 is preferably 1 / 3 to 1 / 2 of the inner diameter of the vertical high-pressure vessel to ensure that the fluid forms a strong turbulent circulation without dead zones within the vessel. For example, it can be between 0.03 and 0.06 m.

[0056] The multi-stage microporous shearing unit 9 is connected to the outlet of the mechanical stirring pre-dispersion unit 7. The specific structure of the multi-stage microporous shearing unit 9 is as follows: Figure 3 As shown, the main body of the multi-stage microporous shearing unit 9 is a high-pressure resistant horizontal tubular structure. Inside, along the flow direction, are sequentially arranged a sintered first stainless steel wire mesh 24, a second stainless steel wire mesh 25, and a porous ceramic membrane plate 26 with uniform pore size. The diameter of both the first stainless steel wire mesh 24 and the second stainless steel wire mesh 25 is 25 mm, and their thickness is 5.0 mm. The mesh count of the first stainless steel wire mesh 24 is preferably 100 to 300 mesh, and the mesh count of the second stainless steel wire mesh 25 is preferably 2000 to 3000 mesh. The first stainless steel wire mesh 24 is used for primary cutting, specifically for "macro-cutting" of millimeter-sized coarse bubbles; the second stainless steel wire mesh 25 is used for secondary cutting, specifically for "micro-cutting."

[0057] Because the subsequent porous ceramic membrane plate 26 is highly sensitive to impurities and large bubble blockages in the fluid, the purpose of the two-stage stainless steel wire mesh is to rectify (homogenize the flow field) and provide protective filtration. The first stainless steel wire mesh 24, with a mesh count below 100, has excessively large openings and cannot provide pre-shearing or rectification; above 300 mesh, it may increase unnecessary flow resistance. The second stainless steel wire mesh 25, with a mesh count below 2000, is insufficient for further bubble refinement; above 3000 mesh, its pore size is close to that of the porous ceramic membrane, which may cause additional pressure loss.

[0058] The porous ceramic membrane plate 26 has an average pore size of 2-5 μm, an outer diameter of 25 mm, and a thickness of 5.0 mm, serving as the final shearing agent. The outlet 27 of the multi-stage microporous shearing unit 9 is designed with a conical contraction structure to minimize ineffective dead volume. The volumetric flow rate of the fluid entering the porous ceramic membrane plate 26 is controlled at 5-10 mL / min. This flow rate range can create pressure difference, throttling expansion, and pore wall shearing effects within the micropores, further breaking down coarse bubbles in the pre-dispersed fluid into micron-sized CO2 microbubbles. For the 1-inch (approximately 2.5 cm) sandstone core used in this embodiment, the volumetric flow rate of the gas-liquid mixture is controlled at 5-10 mL / min to balance the microporous shearing effect within the porous ceramic membrane plate 26 with pressure difference control at the core inlet.

[0059] The outlet end of the multi-stage microporous shearing unit 9 is connected to an online monitoring unit, which includes a visualization online monitoring component 10 and an optical microscope 11, such as... Figure 4 As shown, the online visualization monitoring component 10 includes a high-pressure visualization chamber with an upper sapphire glass 29 and a lower sapphire glass 30, and a high-magnification optical microscope 31 placed on top for observing the internal fluid flow pattern. The distance between the upper sapphire glass 29 and the lower sapphire glass 30 is 1 mm (i.e., the internal height of the high-pressure visualization chamber). The high-pressure visualization chamber has a microfluidic flow channel 32 with a length of 20 mm and a width of 4 mm, used to capture the microbubble particle size morphology and dispersion state in real time.

[0060] The high-pressure visualization chamber includes a metal shell 33 with openings on the upper and lower surfaces. An upper sapphire glass 29 and a lower sapphire glass 30 are installed inside the openings. A microfluidic flow channel 32 is provided between the upper sapphire glass 29 and the lower sapphire glass 30, with both ends extending out of the metal shell 33. One end is the inlet 28 of the high-pressure microfluidic flow cell, and the other end is the outlet 34 of the high-pressure microfluidic flow cell.

[0061] The online monitoring unit is connected to the monitoring computer 19 to enable visualization and analysis of the monitoring results.

[0062] The core displacement unit includes a core holder 13 connected to the outlet 34 of the high-pressure microfluidic flow cell of the online monitoring unit. The core, which is a deep saline sandstone core, is held within the core holder 13. The core holder 13 is housed in a high-temperature constant temperature chamber 14 to maintain the formation temperature of the sandstone core. A low-delay connection pipeline connects the outlet 27 of the multi-stage microporous shear unit to the inlet of the core holder. The low-delay connection pipeline is preferably a high-pressure resistant capillary with an inner diameter of 500 μm and a length preferably controlled within 10 cm to ensure that the fluid transmission time is much shorter than the microbubble coalescence time.

[0063] The residence time of the bubble swarm inside the pipeline is 0.05-10 s. For purely physical CO2 microbubbles without chemical agents, their coalescence half-life is affected by temperature, salinity, and flow state, and can be determined according to the aforementioned definition. In this embodiment, the core external transport time is designed to not exceed 10 s to shorten the residence time between microbubble generation and entry into the core, reducing the possibility of significant coalescence or gas-liquid stratification during transport. To minimize the residence time of CO2 microbubbles outside the core, a high-pressure resistant capillary with an inner diameter of 0.25-1 mm and a length of 5-20 cm is used at a volumetric flow rate of 5-10 mL / min. The total residence time of CO2 microbubbles from the generation outlet of the multi-stage microporous shear unit 9 through the online monitoring unit to the core inlet is not more than 10 s, and preferably less than their coalescence half-life.

[0064] The 1 L vertical high-pressure vessel, 25 mm diameter microporous shearing unit, 5-10 mL / min fluid flow rate, low-delay capillary, and high-magnification optical observation device described in this embodiment are example configurations under core-scale implementation and evaluation conditions. The above equipment dimensions and operating parameters do not constitute a limitation on the engineering application to the target reservoir. In engineering applications, the effective size of the pre-dispersion vessel and microporous shearing unit can be increased according to the required flow rate. Alternatively, multiple microporous shearing modules can be operated in parallel, with the microbubble generation module located at the wellhead, near the wellbore, or downhole.

[0065] The back pressure control unit includes a back pressure valve 17, which is connected to the outlet of the core holder 13 to control the back pressure of the overall displacement system. The back pressure valve 17 is connected to a liquid receiving cylinder 18 for collecting fluid.

[0066] Example 3 This embodiment provides a specific operation method for the CO2 microbubble enhanced geological mineralization injection system provided in Embodiment 2, specifically including: S1. System preparation and parameter setting; Simulated saline water with the same ionic composition as the target saline aquifer was prepared, for example, with a salinity of 23,000 mg / L. A natural sandstone saline aquifer core (25 mm in diameter and 75 mm in length) was vacuumed, saturated with simulated saline water, and then loaded into the core holder 13. The system confining pressure was set to 17 MPa by the confining pressure control pump 15, the back pressure value of the back pressure valve 17 was set to 12 MPa, and the temperature in the high-temperature constant temperature chamber 14 was adjusted to 50 °C.

[0067] S2, mechanical reconstruction of bubble flow pattern; Turn on the high-pressure injection pump 2, and set the injection flow rate of both simulated saline water and CO2 to 2.5 mL / min (gas-liquid ratio 1:1). Simultaneously, the mixture enters the high-pressure resistant mechanical stirring pre-dispersion unit 7 and is turned on. The preferred rotation speed of the mechanical stirring pre-dispersion unit 7 is 2000-6000 rpm. In order to break the gas-water interface without using a chemical foaming agent, the Reynolds number of the system must be higher than 10. 4 The upper limit of 6000 rpm is the engineering limit of magnetic seals or mechanical seals under high temperature and high pressure environments. Excessive speed may damage the sealing performance of the container.

[0068] Calculated based on the Reynolds number formula:

[0069] in, Re Represents the Reynolds number. ρ Indicates the density of salt water. N For stirring speed, D This indicates the outer diameter of the agitator blades. μ This refers to the fluid dynamic viscosity.

[0070] Calculated Reynolds number Re Characterizes the fluid state, when Re <10 indicates laminar flow region, 10< Re <10 4 This is the transitional flow region. Re >10 4 This is the fully turbulent region.

[0071] This invention limits the diameter of the stirring blades and the stirring speed, thereby restricting the fluid to a strong turbulent state. Under strong turbulent conditions, the macroscopic CO2-saltwater interface is forcibly broken up, and the originally discontinuous gas column is dispersed into a group of millimeter-sized coarse bubbles that are visible to the naked eye. The flow pattern is reconstructed from an unstable slug flow to a uniform clump flow or fine bubble flow. At the same time, strong turbulence accelerates the dissolution of CO2 in the aqueous phase and increases the degree of pre-dissolution of CO2 in the aqueous phase.

[0072] S3. Online generation of CO2 microbubbles under the multi-level microporous membrane effect; The pre-dispersed CO2-saltwater mixture immediately enters the multi-stage microporous shear unit 9. Driven by pressure difference, the fluid sequentially passes through a 200-mesh first stainless steel wire mesh 24, a 2000-mesh second stainless steel wire mesh 25, and a porous ceramic membrane plate 26. The apparent volumetric flow rate of the fluid entering the porous ceramic membrane plate 26 is controlled at 5-10 mL / min; in this embodiment, 5 mL / min is used. Under these conditions, the fluid generates high-order-of-magnitude shear stress within the micropores.

[0073] Utilizing the "micropore throttling-expansion" effect and pore wall shear force under chemical-free conditions, coarse bubbles are further cut and pulverized. An online monitoring component is used to observe the morphology and dispersion state of the micron-sized CO2 dispersed phase. By adjusting the stirring speed, gas-liquid ratio, shear medium pore size, and flow rate, the dispersion is further refined. 50 The preferred size is controlled within the range of 5–20 μm. Figure 5 This is only intended to illustrate the differences in the transport of CO2 dispersed phases of different sizes in porous media, and does not represent actual microscopic observation results or particle size statistics.

[0074] S4, Low-delay injection of metastable microbubbles; The generated microbubble fluid is directly introduced into the core via a low-delay connection pipeline. Calculations show that the effective volume of the microfluidic flow channel in the online monitoring unit is approximately 0.08 mL, the effective volume of the high-pressure capillary is approximately 0.02 mL, and the total effective volume of the CO2 microbubble swarm from the porous ceramic membrane plate 26 to the core cross-section is approximately 0.10 mL. At a flow rate of 5 mL / min, the theoretical residence time of the CO2 microbubble swarm is approximately 1.2 s. This indicates that, under the above core-scale design parameters, the transport time from CO2 microbubble generation to entry into the core can be shortened by reducing the external transport volume.

[0075] The 1.2 s mentioned above is a theoretical core-scale value obtained based on the design parameters of this embodiment, and does not represent the same delivery time during the engineering injection process of the target reservoir. When used for the target reservoir, the delivery time should be re-determined based on the microbubble generation location, wellbore length, pipeline volume, and engineering injection flow rate, and the delivery path should be shortened by deploying microbubble generation units at the wellhead, near the well, or downhole.

[0076] S5 and CO2 microbubble deep migration and enhanced mineralization; After CO2 microbubbles enter the core, their transport capacity within the pore throat is related to factors such as microbubble size, pore throat size, interfacial tension, and injection pressure differential. When the microbubble size is compatible with the target core pore throat size, it helps reduce interfacial blockage and additional capillary resistance caused by excessively large dispersed phase sizes, and increases the likelihood of CO2 dispersed phase entering smaller pore throats, thereby expanding the CO2-water-rock contact range. This paragraph is only used to illustrate a possible mechanism and does not represent experimental test results indicating a specific pore throat matching relationship or affected range.

[0077] On the other hand, after microbubbles enter the micropores, the additional interfacial pressure created by their curvature, combined with the higher gas-liquid contact area, shorter diffusion distance, and continuous interfacial renewal, collectively enhances the mass transfer rate of CO2 to pore water. This allows the locally dissolved CO2 concentration to more quickly approach the gas-liquid equilibrium state under the corresponding temperature, pressure, and mineralization conditions, and forms a locally acidic environment with a lower pH. This locally acidic environment promotes the dissolution of silicate minerals such as feldspar, releasing Ca2+. 2+ Mg 2+ Fe 2+ Metal ions, and further promote the formation of carbonate minerals.

[0078] Example 4 This embodiment provides a parameter design method for the CO2 to aqueous phase volumetric flow rate ratio determined based on a core model or the permeability of the target reservoir. The following gas-liquid ratio is a preferred design range, which can be adjusted according to the pore throat structure, liquid absorption capacity, allowable injection pressure, and microbubble dispersion state during experimental application.

[0079] When the permeability of the core model or target reservoir satisfies 1 mD ≤ K < 10 mD, the volumetric flow rate ratio of CO2 to formation water or simulated saline water can be set to 1:20 to 1:5 to form a low number density of CO2 microbubble flow and reduce the superimposed capillary force generated by multiple dispersed phases at narrow pore throats.

[0080] When the permeability of the core model or target reservoir meets the condition 10 mD ≤ K < 50 mD, the volumetric flow rate ratio of CO2 to formation water or simulated saline water is controlled at 1:5 to 1:2 to balance the ability of CO2 microbubbles to enter the pore throat and the number density of bubbles, reduce gas channeling in the dominant channel, and improve the sweepability of the medium and low permeability areas.

[0081] When the permeability of the core model or target reservoir meets K ≥ 50 mD: the volumetric flow rate ratio of CO2 to formation water or simulated saline water is adjusted to 1:2 to 1:1 to increase the number density of CO2 microbubbles and the CO2-water interface area.

[0082] Under low-permeability, dense saline aquifer conditions, reducing the gas-liquid ratio generates low-number-density microbubble flow, minimizing the superposition resistance of bubbles at the pore throat. This model focuses on utilizing the "deep-penetration" properties of microbubbles to transport highly chemically active carbon sources to the depths of the dense matrix, primarily enhancing mass transfer and dissolution within the matrix pores and promoting deep mineralization.

[0083] Under medium-to-high permeability saline aquifer conditions, increasing the gas-liquid ratio generates high-density microbubble flow, increases the gas-liquid interface area, and enhances CO2 mass transfer and CO2-water-rock contact.

[0084] The parameters mentioned above are used to illustrate the design principles under different permeability conditions and do not represent that the field injection verification of the corresponding target reservoir has been completed.

[0085] Example 5 This embodiment provides a pulsed injection scheme for simulating and evaluating the risk of localized precipitation and blockage in the near-wellbore zone at the core scale. Based on Embodiment 3, step S4 employs a "microbubble pulsed injection" strategy. The specific operation is as follows: Injection procedure: Alternately inject "CO2 microbubble fluid slug" and "simulated saline water slug" into the core; Specific parameters: The volume of a single injection of CO2 microbubble fluid slug is 0.2-0.5 times the pore volume (PV). For the core used in this embodiment, the volume is 0.2-0.5 PV.

[0086] The volume of the simulated saline slug injected in a single cycle is set to 0.3-1.0 PV. It is essential to ensure that the volume of the flushing slug is always larger than that of the reaction slug (i.e., the CO2 microbubble fluid slug). The injection flow rate is the same as the CO2 microbubble fluid injection flow rate.

[0087] Functional division: CO2 microbubble fluid slugs are used to provide highly chemically active acidic fluids that enter the micropores to promote the CO2-saline water-rock reaction; simulated saline water is used to reduce the local ion supersaturation in the inlet area and promote the migration of dissolved metal ions and fine suspended particles to the deeper parts of the core, reducing the risk of premature precipitation and local precipitation in the near-inlet area.

[0088] The acidic environment created by CO2 microbubbles may promote the dissolution of reservoir minerals and increase the concentration of dissolved ions in localized areas. When the local solution reaches supersaturation, there is a possibility that minerals such as carbonates may precipitate and accumulate near the inlet area. Therefore, a relatively large simulated saline slug can be installed to dilute local reactants, promote the migration of dissolved components and fine suspended particles to deeper parts of the core, thereby reducing the risk of premature precipitation and local blockage near the inlet area and helping to maintain fluid injection capacity.

[0089] When used for target reservoirs, the pulse injection principle at the core scale can be applied to the design of injection parameters in the near-wellbore zone. The specific slug volume and injection cycle are determined based on the target treatment volume, fluid absorption capacity, injection pressure changes, and flowback fluid composition in the near-wellbore zone.

[0090] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention do not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A method for CO2 microbubble-enhanced geological mineralization preservation, characterized in that, include: S1. Without adding chemical foaming agents, surfactants, or nano-stabilizers, introduce gaseous or supercritical CO2 and simulated saline water or formation water into the injection system, and set the injection pressure P. inj , so that its P pore <P inj <P frac , where P pore For the target saline aquifer pore pressure, P frac The target saline aquifer rock fracture pressure; S2. Mix the aqueous phase and gaseous or supercritical CO2, and perform mechanical stirring pre-dispersion treatment to form a strong turbulent shear field in the fluid, reconstructing the discontinuous gas slugs into agglomerate flow, forming a pre-dispersed gas-liquid mixed flow. S3. The gas-liquid mixture is subjected to multi-stage microporous shearing treatment, and is sheared step by step through stainless steel wire mesh, porous ceramic membrane plate or sintered metal medium to generate metastable CO2 microbubble fluid. S4. The metastable CO2 microbubble fluid is transported and injected into the core or target reservoir before significant aggregation or gas-liquid stratification, so that the CO2 microbubbles enter the porous medium while maintaining a dispersed state. S5. Under the target reservoir temperature and pressure conditions, the CO2 microbubbles are brought into contact with pore water and reservoir minerals to increase the mass transfer rate of CO2 to pore water and expand the CO2-water-rock contact range.

2. The method according to claim 1, characterized in that, In step S2, the stirring speed for the mechanical stirring pre-dispersion treatment is 2000-6000 rpm, and the stirring Reynolds number is kept constant. Re >10 4 ; The multi-stage microporous shearing in step S3 is completed by a multi-stage microporous shearing unit. The multi-stage microporous shearing unit includes, in sequence along the fluid flow direction, a first stainless steel wire mesh, a second stainless steel wire mesh, and a multi-stage microporous shearing medium. The microporous shearing medium is a porous ceramic membrane or a sintered metal medium. The first stainless steel wire mesh has a mesh count of 100-300 mesh, the second stainless steel wire mesh has a mesh count of 2000-3000 mesh, and the porous ceramic membrane has an average pore size of 2-5 μm.

3. The method according to claim 1, characterized in that, Under core-scale injection and evaluation conditions, in step S3, the volumetric flow rate of the gas-liquid mixture formed by CO2 and water phase entering the porous ceramic membrane or sintered metal medium is controlled at 5–10 mL / min, so as to generate a pressure difference, throttling expansion effect and pore wall shearing effect sufficient to break coarse bubbles in the microchannel. In the CO2 microbubble fluid generated in step S3, the d of the CO2 microbubbles 50 The particle size is 5–20 μm.

4. The method according to claim 1, characterized in that, Under core-scale injection and evaluation conditions, the multi-stage micropore shearing treatment in step S3 is completed by a multi-stage micropore shearing unit; in step S4, the outlet of the multi-stage micropore shearing unit is connected to the inlet of the online monitoring unit, and the outlet of the online monitoring unit is connected to the core inlet through a low-delay connection pipeline; the low-delay connection pipeline is a high-pressure resistant capillary with an inner diameter of 0.25-1 mm and a length of 5-20 cm, and the total residence time of the CO2 microbubble fluid from the outlet generated by the multi-stage micropore shearing unit to the core inlet via the online monitoring unit does not exceed 10 s.

5. The method according to claim 1, characterized in that, In step S1, the volume ratio of CO2 to formation water or simulated saline water is adjusted according to the permeability of the target saline aquifer: when the saline aquifer permeability satisfies 1 mD ≤ K < 10 mD, the volume ratio of CO2 to formation water or simulated saline water is 1:20 to 1:5; when the saline aquifer permeability satisfies 10 mD ≤ K < 50 mD, the volume ratio of CO2 to formation water or simulated saline water is 1:5 to 1:2; when the saline aquifer permeability satisfies K ≥ 50 mD, the volume ratio of CO2 to formation water or simulated saline water is 1:2 to 1:

1.

6. The method according to claim 1, characterized in that, In step S4, the metastable CO2 microbubble fluid is injected in a pulsed manner, alternating between CO2 microbubble fluid slugs and formation water or simulated saline water slugs; Under core-scale injection and evaluation conditions, the volume of a single CO2 microbubble fluid slug injected is 0.2-0.5 PV, and the volume of a single formation water or simulated saline water slug injected is 0.3-1.0 PV. The volume of a single formation water or simulated saline water slug injected is higher than that of a single CO2 microbubble fluid slug injected.

7. The method according to claim 2, characterized in that, It also includes online monitoring and feedback adjustment steps: an online monitoring unit installed at the outlet of the multi-stage microporous shearing unit is used to monitor the particle size distribution and dispersion state of CO2 microbubbles in real time; when CO2 microbubbles are detected... 50 When the CO2 microbubbles are >20 μm or when significant stratification occurs between water and CO2, increase the stirring speed of the mechanical stirring pre-dispersion treatment or increase the volumetric flow rate of the fluid entering the porous ceramic membrane or sintered metal medium until the CO2 microbubbles reach a certain size. 50 It recovered to the 5-20 μm range and the gas-liquid stratification phenomenon disappeared.

8. A CO2 microbubble-enhanced geological mineralization injection system for implementing the method of any one of claims 1-7, characterized in that, include: The fluid injection unit is used to simultaneously inject gaseous or supercritical CO2 and formation water or simulated saline water according to a set ratio. A mechanical stirring pre-dispersion unit, connected to the fluid injection unit, is used to mechanically stir and pre-disperde CO2 with formation water or simulated saline water to form a pre-dispersed gas-liquid mixture. A multi-stage microporous shearing unit, connected to the mechanical stirring and pre-dispersion unit, is used to perform stepwise microporous shearing on the gas-liquid mixture to generate metastable CO2 microbubble fluid. An online monitoring unit, connected to the outlet end of the multi-stage microporous shearing unit, is used to observe the particle size distribution and dispersion state of the generated CO2 microbubble fluid online. The core displacement unit is connected to the outlet end of the online monitoring unit via a low-delay connection pipeline or a low-delay connection line. A back pressure control unit, which is connected to the core displacement unit, is used to control the system back pressure.

9. The system according to claim 8, characterized in that, The mechanical stirring and pre-dispersion unit includes a vertical high-pressure vessel. A motor is installed at the top of the vertical high-pressure vessel, and a central shaft is installed inside. The motor is connected to the central shaft. Multiple layers of stirring blades are installed on the central shaft. Multiple baffles are vertically installed on the inner wall of the vertical high-pressure vessel. The outer diameter of the stirring blades is 1 / 3 to 1 / 2 of the inner diameter of the vertical high-pressure vessel. The multi-stage microporous shearing unit includes a high-pressure resistant horizontal tubular shell. Inside the high-pressure resistant horizontal tubular shell, a first stainless steel wire mesh, a second stainless steel wire mesh, and a porous ceramic membrane are arranged sequentially according to the liquid flow direction. The tail of the high-pressure resistant horizontal tubular shell has a conical contraction structure to reduce the ineffective dead volume of the multi-stage microporous shearing unit.

10. The system according to claim 8, characterized in that, It also includes a pressure and temperature control unit, which includes a CO2 pressurization component, a confining pressure control component, a constant temperature component, and a pressure monitoring component; the CO2 pressurization component is disposed between the CO2 gas source and the mechanical stirring and dispersing unit, the confining pressure control component is connected to the confining pressure chamber of the core holder, the constant temperature component is used to maintain the temperature of the core displacement unit, and the pressure monitoring component is used to monitor the pressure of the CO2 injection pipeline, the microbubble generation and delivery pipeline, and / or the core displacement unit; The online monitoring unit is located between the outlet end of the multi-stage microporous shearing unit and the inlet end of the core displacement unit; the online monitoring unit includes a high-pressure visualization chamber and a high-magnification optical microscope, the high-pressure visualization chamber includes a metal shell, an upper sapphire glass, a lower sapphire glass, and a microfluidic flow channel located between the two sapphire glass pieces; the outlet end of the online monitoring unit is connected to the inlet end of the core displacement unit through a low-delay pipeline or a low-delay connecting line.

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