Manufacture of micro-models for carbonate reservoirs

Abstract

Carbonate microfluidic models and methods having controllable nanoscale porosity are described. Methods for making carbonate nanofluidic micro-models having controllable nanoscale porosity for studying fluid behavior in subsurface petroleum reservoir environments include: arranging a plurality of polymer spheres in a transparent flow cell; initiating crystallization of the plurality of polymer spheres to form a template having a opal structure; filling the transparent flow cell with a calcium-based solution and a carbonate-based solution to form nanocrystals in interstices of the opal structure; and removing the template formed by crystallization of the plurality of polymer spheres from the transparent flow cell, leaving a reverse opal structure having a plurality of nanoscale pores and a carbonate surface. The model includes: a transparent flow cell including a first end defining an inlet and a second end defining an outlet; and a reverse opal structure of carbonate within the transparent flow cell.

Description

[0001] Priority Statement

[0002] This application claims priority to U.S. Patent Application No. 17 / 140,773, filed January 4, 2021, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure generally relates to a method for fabricating micromodels for studying fluid behavior in underground oil reservoir environments, and more specifically to a method for fabricating nanofluid micromodels with nanoscale porosity. Background Technology

[0004] With increasing global demand for oil and a declining rate of new oil field discoveries, it is crucial to improve the oil production efficiency of existing oil fields. Many of the world's reservoirs trap approximately two-thirds of the oil in locations inaccessible using current production methods. To improve oil extraction efficiency, it is essential to better understand the multiphase fluid behavior within subsurface oil reservoirs and the interactions between oil-water-rock facies.

[0005] A large portion of the world's oil reserves are found in carbonate reservoirs. For example, it is estimated that approximately 70% of the oil and 90% of the natural gas reserves in the Middle East are contained in carbonate reservoirs. Typically, carbonate rocks are primarily composed of calcite (CaCO3) and dolomite (CaMg(CO3)2). Based on studies of carbonate reservoir rocks in the Arabian Peninsula, calcite content is greater than 90 wt.% at typical reservoir depths, and even reaches 100 wt.% at some depths. Summary of the Invention

[0006] This specification describes carbonate nanofluidic micromodels that can be used to study fluid behavior in subsurface oil reservoir environments, as well as methods for fabricating and using these models. The models and methods described in this specification provide chemical procedures for fabricating microfluidic chips or pools (i.e., nanofluidic chips or nanofluidic pools) with nanoscale porosity and surfaces of calcium carbonate (CaCO3), calcium magnesium carbonate (CaMg(CO3)2), or both. The nanofluidic micromodels can be used as carbonate micromodels for oil and gas reservoir applications.

[0007] In the described manufacturing process, commercially available quartz or glass flow cells or chips and polystyrene (PS) colloidal spheres are used. The PS spheres are essentially monodisperse and have characteristic dimensions between 50 and 1000 nanometers (nm). They are synthesized via a colloidal synthesis method. The PS spheres are assembled within the cells to form a template with a colloidal or photonic crystal structure. After assembly, the voids in the template are filled by in-situ growth of CaCO3 nanocrystals (simulating calcite) or nanocrystals containing CaMg(CO3)2 (simulating dolomite). Because the PS spheres surrounded by nanocrystals are tightly packed in a near-three-dimensional (3D) close-packed colloidal structure, the voids between the nanocrystal-filled spheres form a nanostructure network of calcite or dolomite. When the colloidal template is removed, an inverse opal structure of calcite or dolomite is generated within the cells, where the three-dimensional (3D) void network from the negative replica of the template provides pores and channels in the nanoscale range, i.e., nanoscale porosity.

[0008] In some aspects, methods for fabricating carbonate nanofluid micromodels with controllable nanoscale porosity for studying fluid behavior in subsurface oil reservoir environments include: arranging a plurality of polymer spheres in a transparent flow cell; initiating crystallization of the plurality of polymer spheres to form a template with an opal structure; filling the transparent flow cell with a calcium-based solution and a carbonate-based solution to form nanocrystals in the voids of the opal structure; growing an inverse opal structure of calcium carbonate or calcium magnesium carbonate in the opal-structured template; and removing the template formed by the crystallization of the plurality of polymer spheres from the transparent flow cell, leaving the inverse opal structure with multiple nanoscale pores and a carbonate surface.

[0009] Examples of methods for fabricating carbonate nanofluid models with controllable nanoscale porosity may include one or more of the following features.

[0010] In some embodiments, the transparent flow cell has an optical path between 0.05 and 1 millimeter (mm) and a volume between 16 and 300 microliters (μL).

[0011] In some embodiments, the method further includes synthesizing a plurality of polymer spheres. In some cases, the plurality of polymer spheres have characteristic dimensions between 50 nanometers (nm) and 1000 nm, and the carbonate nanofluid model has a resulting controllable porosity between 50 and 1000 nm. In some cases, the method further includes purifying the plurality of polymer spheres in deionized water and redispersing the plurality of polymer spheres in ethanol or a 1:1 water-ethanol mixture.

[0012] In some embodiments, the method further includes crystallizing and solidifying multiple polymer spheres in a transparent flow cell by drying at 60 degrees Celsius (°C) for 30 minutes.

[0013] In some embodiments, the method further includes forming a calcium-based or calcium / magnesium-based solution and injecting the solution into a transparent flow cell. In some cases, 1M Ca 2+ The solution formation involves dissolving a solid CaCl₂·2H₂O solution in deionized water as a precursor for calcite formation. In some cases, 1M(Ca 2+ +Mg 2+ The solution is formed by mixing CaCl₂·2H₂O solution and MgCl₂·6H₂O solution in a 1:1 molar ratio (or, as desired, a 1:1 to 1:3.5 ratio of CaCl₂·2H₂O solution). 2+ / Mg 2+ The mixture (in molar ratio) is dissolved in deionized water as a precursor for the formation of dolomite. In some cases, the formation of CaCO3 or CaMg(CO3)2 crystals in a transparent flow cell involves dissolving 1M CO3... 2- Injected into a transparent flow cell to react with calcium- or calcium / magnesium-based ions. In some cases, 1M CO3 is formed. 2- This includes dissolving Na₂CO₃ or (NH₄)₂CO₃ solution in deionized water. In some cases, the method also includes mixing a calcium-based or calcium / magnesium-based solution with CO₃²⁻. 2- The solution was alternately injected into a transparent flow cell multiple times and dried at 150°C for 2 hours to fill the voids of the transparent flow cell with CaCO3 or CaMg(CO3)2 crystals.

[0014] In some embodiments, the method further includes immersing a transparent flow cell in a toluene solution overnight to dissolve a plurality of polymer spheres embedded in calcite or dolomite. In some cases, the method further includes injecting a toluene, chloroform, or acetone solution into the transparent flow cell to wash the dissolved plurality of polymer spheres. In some cases, the method also includes forming an inverse opal structure with multiple nanoscale pores in the calcite or dolomite network by sintering the transparent flow cell at 280°C for 2 hours.

[0015] In some aspects, the carbonate nanofluid micromodel with nanoscale porosity includes: a transparent flow cell comprising a first end defining an inlet and a second end defining an outlet; and an inverse opal structure within the transparent flow cell, the inverse opal structure being formed of calcium carbonate having multiple nanoscale pores.

[0016] Examples of carbonate nanofluid micromodels with nanoscale porosity may include one or more of the following features.

[0017] In some embodiments, the carbonate nanofluid micromodel has a second end with a filter.

[0018] In some embodiments, the transparent flow cell is a removable quartz cell. In some cases, the transparent flow cell is also a microflow cell.

[0019] In some embodiments, the inverse opal structure comprises a three-dimensional (3D) network having a plurality of interconnected voids. In some cases, the plurality of interconnected voids have controllable nanoscale feature sizes between 50 and 1000 nm. In some cases, the inverse opal structure has a calcium carbonate or calcium-magnesium carbonate surface.

[0020] Carbonate nanofluidic pools provide a simple and useful micromodeling system for simulating carbonate reservoirs. This approach allows for the study of oil-water phase behavior and fluid-surface interactions, such as rock-fluid interactions, at nanoscale porosity using small-volume samples and at low cost. The surface of the nanofluidic pool is optically transparent, allowing direct visualization of the interactions between the fluid and the nearby carbonate or dolomite using a variety of characterization tools, such as advanced spectroscopic and microscopic techniques. The resulting data provide valuable information for increasing / improving oil recovery rates.

[0021] This technology involves a cost-effective chemical method for fabricating microfluidic chips with precisely controlled porosity at the nanoscale, which is smaller than that achieved by current methods such as photolithography. This method enables the transformation of ordinary flow cells into nanofluidic cells. Nanofluidic cells can be used as efficient carbonate micromodeling systems for studying fluid behavior within nanoscale porosity. More specifically, the model enables the understanding of nanoscale oil-water phase behavior and rock-fluid interactions. Reservoir micromodels can be used to simulate subsurface oil reservoir environments for submicron-level multiphase flow studies, enhancing / improving oil recovery rates, and mapping reservoir networks. The disclosed micromodels represent the geochemical surface characteristics of carbonate reservoir rocks.

[0022] The following figures and description illustrate details of one or more embodiments of these systems and methods. Other features, objects, and advantages of these systems and methods will be apparent from the description, figures, and claims. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of a wellbore that has penetrated a carbonate reservoir.

[0024] Figure 2 This is a schematic diagram showing oil trapped between rocks.

[0025] Figures 3A-3D This is a view of an exemplary transparent flow tank and tank support.

[0026] Figures 4A-4C This is a perspective view showing a variation of the transparent flow cell.

[0027] Figure 5 This is a schematic diagram illustrating a method for assembling PS spheres in a microfluidic pool, followed by the growth of calcium carbonate nanocrystals to fill the voids around the spheres, thus forming a nanofluidic pool.

[0028] Figure 6A and Figure 6B This is a schematic diagram illustrating a method for creating a micromodel with controllable nanoporosity for carbonate reservoirs.

[0029] Figures 7A-7B These are schematic diagrams of simple cubic stacked opal and inverse opal structures, respectively.

[0030] Figures 8A-8B These are schematic diagrams of close-packed opal and inverse opal structures, respectively.

[0031] Figures 9A-9B These are scanning electron micrographs of nanoscale PS spheres and calcium carbonate pores, respectively. Detailed Implementation

[0032] This specification describes carbonate nanofluidic micromodels that can be used to study fluid behavior in subsurface oil reservoir environments, as well as methods for fabricating and using these models. The models and methods described in this specification provide chemical procedures for fabricating microfluidic chips (i.e., nanofluidic chips) with nanoscale porosity and surfaces of calcium carbonate (CaCO3), calcium magnesium carbonate (CaMg(CO3)2), or both. The nanofluidic models can be used as carbonate micromodels for oil and gas reservoir applications.

[0033] In the described manufacturing process, commercially available quartz or glass flow cells or chips and polystyrene (PS) colloidal spheres are used. The PS spheres are substantially monodisperse and have characteristic dimensions between 50 and 1000 nanometers (nm). They are synthesized via a colloidal synthesis method. The PS spheres are assembled within the cell to form a template with a colloidal or photonic crystal structure. After assembly, the voids in the template are completely filled by in-situ growth of CaCO3 nanocrystals (simulating calcite) or a layer of nanocrystals containing CaMg(CO3)2 (simulating dolomite). Because the PS spheres are densely packed in a near-three-dimensional (3D) close-packed colloidal structure, the nanocrystals filling the voids between the spheres form a nanostructured network framework of calcite or dolomite. When the colloidal template is removed, an inverse opal structure of calcite or dolomite is generated within the cell, where the three-dimensional (3D) void network provides pores and channels with controllable sizes in the nanoscale range. This method enables the transformation of ordinary flow cells into nanofluidic cells. Nanofluidic cells can be used as an effective carbonate micromodel system for studying fluid behavior in nanoscale porosity.

[0034] Figure 1 This is a schematic diagram of a wellbore 102 drilled through a carbonate reservoir 101. The carbonate reservoir 101 comprises multiple geological layers 103, 104, 105, 106, 107, 108, and 109, which may be rock layers or salt layers. A drilling rig 100 or other completion equipment is used to process the wellbore 102 in the carbonate reservoir 101. This can be achieved by techniques that create fractures or other openings in the carbonate reservoir 101 to recover oil trapped in porous rock 110. The porosity of a reservoir is the fraction of the total volume of porous media occupied by pore space, and thus reflects the reservoir rock's ability to contain or store fluids.

[0035] Figure 2 This is a schematic diagram illustrating oil 132 trapped between rocks 110. High fractions of nanoporosity (e.g., 20+%) may exist in carbonate reservoirs. However, the majority of the pore space comprises micrometer-sized pores, which provide microporosity throughout the formation. Nanopores can be 1000 times smaller and more compact than micropores. Understanding the multiphase flow behavior in carbonate reservoirs is important for determining effective treatments to improve production. As mentioned above, the fabricated nanofluidic chips with controllable porosity and surface chemistry can be used as micro-modeling systems for studying multiphase fluid behavior. The nanofluidic chips have demonstrated usefulness in water injection experiments for studying oil displacement in nanopores and in electrodynamic diffusion experiments with closed-end nanopore structures.

[0036] Figures 3A-3DThis is an exemplary transparent flow cell 152 and cell holder 210. For prototyping, a commercially available transparent flow cell 152 can be used. The transparent flow cell 152 can be a removable quartz (SiO2) cell or a microflow cell (e.g., a Hellma cell and a Starna cell). The transparent flow cell 152 includes a rectangular body 154 with a central cutout 158 ​​(the cutout includes an elliptical shape with rectangular edges), a top cylindrical extruder 160a, and a bottom cylindrical extruder 160b. Figure 3A The top cylindrical extruder 160a defines the inlet, and the bottom cylindrical extruder 160b defines the outlet.

[0037] Figure 3B An exploded view of the transparent flow cell 152 is shown. Figure 3C A side view of the assembled transparent flow cell 152 is shown, which includes a filter 190 inserted into a bottom cylindrical extrusion 160b. The filter 190 has a size of 0.45 micrometers (μm) and retains PS nanospheres within the cell 152. The transparent flow cell 152 has an optical path between 0.05 and 1 millimeter (mm) and a volume between 16 and 300 microliters (μL). During laboratory experiments, the transparent flow cell 152 was mounted within a cell holder 210. Figure 3D The pool support 210 includes a rectangular elongated body 212 with a central cutout 214 on all four sides, and four mounting screws 216a, 216b, 216c, and 216d to hold the flow pool 152 in place. In some embodiments, the flow pool 152 may include flow pools of various shapes. A micromodel for a carbonate reservoir was created using a transparent flow pool.

[0038] Figures 4A-4C This is a perspective view showing a variation of the transparent flow cell. Figure 4A A flow cell 236 is shown, having an elliptical body 238 and cylindrical extrusions 240a, 240b on each side of the body 238. Figure 4B A flow cell 242 is shown having a rectangular body 244 and thin cylindrical extrusions 246a, 246b on each side of the body 244. Figure 4C A flow cell 248 with the same shape as the flow cell 152 described in FIG3 is shown.

[0039] Figure 5This is a schematic diagram illustrating a method 272 for assembling PS spheres 274 and 276 in a microfluidic chip, and growing calcium carbonate filler 278 around the PS spheres to form a nanofluidic chip 280. The procedure creates nanoscale pores or channels in a calcium carbonate (CaCO3) fluidic chip. In one example, the nanofluidic chip is fabricated from a commercially available glass or quartz microfluidic chip 152 with two-dimensional (2D) microscale channels and porosity. Various microfluidic chips with micron-sized porosities (i.e., micropores or microchannels) are commercially available. Next, monodisperse PS colloidal nanospheres synthesized via a colloidal synthesis method are arranged in the 2D microchannels of a transparent flow cell 152. Crystallization 276 is then initiated to form a 3D close-packed opal structure within the microchannels or template. This creates voids between the spheres, and these voids form a 3D interconnected channel network. The channel size can be controlled in the nanoscale or submicron range, depending on the size of the PS spheres used. In this example, the PS spheres have a uniform size. To make the model chemically similar to a carbonate reservoir, calcium-based solutions and CO3-based solutions were compared. 2- The solution was alternately arranged in the pool and microchannels to form calcium carbonate 278 by an in-situ chemical filling process. The template 280 was then removed from the transparent flow cell 152, leaving an inverse opal structure of calcium carbonate with multiple nanoscale pores.

[0040] Figure 6A and Figure 6B This is a schematic diagram illustrating method 300 for fabricating a micromodel with nanoporosity for carbonate reservoirs. Method 300 begins in step 302, synthesizing monodisperse PS spheres. The PS spheres are purified in deionized water and redispersed in ethanol or a 1:1 water-ethanol mixture. A PS suspension with a concentration between 2 and 10 wt.% is arranged in a transparent flow cell 152. In step 304, the spheres are assembled in the transparent flow cell 152 to form colloidal crystals. A nitrogen stream is then injected to dry the colloidal crystals and they are further dried at 60 degrees Celsius (°C) for 30 minutes. In step 306, calcite crystals Ca... 2+ The solution was injected into a transparent flow cell 152. 1M Ca was prepared by dissolving solid calcium chloride (CaCl2·2H2O) in deionized water (H2O) as a precursor for calcite formation. 2+ The solution was prepared by dissolving CaCl₂·2H₂O and magnesium chloride (MgCl₂·6H₂O) in deionized H₂O at a 1:1 molar ratio as precursors for the formation of dolomite, and 1M(CaCl₂·2H₂O) was prepared by dissolving CaCl₂·2H₂O and magnesium chloride (MgCl₂·6H₂O) in deionized H₂O as precursors for the formation of dolomite. 2+ +Mg 2 + ) solution. Add Ca 2+ or (Ca) 2+ +Mg 2+The solution is injected into the cell to fill the voids around the colloidal crystals. In step 308, CO3 is... 2- The solution was injected into a transparent flow cell 152. 1M CO3 was prepared by dissolving sodium carbonate (Na2CO3) or ammonium carbonate ((NH4)2CO3) in deionized H2O. 2- Solution. Add CO3 2- The solution is injected into the pool to react with Ca. 2+ or (Ca) 2+ +Mg 2+ ) Ionic reactions, and in situ formation of CaCO3 or CaMg(CO3)2 crystals through the following net reaction:

[0041] Ca 2+ +CO3 2- →CaCO3↓

[0042] Ca 2+ +Mg 2+ +2CO3 2- →CaMg(CO3)2↓

[0043] The process of forming CaCO3 or CaMg(CO3)2 is repeated multiple times until all voids around the spheres are completely filled. This composition can be used to tune surface properties to more closely match the chemical composition of a specific carbonate reservoir. For example, other elements may also be included in the solution to form a thin layer, including, for example, aluminum, silicon, zinc, iron, copper, manganese, titanium, vanadium, or other elements, or combinations thereof, which may be found in the target reservoir. In this example, calcium carbonate nanocrystals are grown around PS spheres to form a microfluidic model to simulate the properties of a calcium carbonate reservoir. In step 310, the pool is dried at 150°C for 2 hours to solidify the CaCO3 or CaMg(CO3)2 network. In step 312, pool 152 is immersed overnight in toluene in a sealed container to dissolve the PS colloidal crystals, and then toluene, chloroform, or acetone is injected into pool 152 to wash the dissolved PS spheres. Finally, the pool 152 containing the negative CaCO3 or CaMg(CO3)2 replicas constructed with PS colloidal crystals was sintered at 280°C for 2 hours.

[0044] Figures 7A-7B These are schematic diagrams showing a simple cubic stacked opal 332 with a packing density of 52.4% and an inverse opal structure 334 with a porosity density of 47.6%, respectively. Figures 8A-8BSchematic diagrams are shown for a closely packed opal structure 354 with a packing density of 70.5% and an inverse opal structure 356 with a porosity of 29.5%. An opal structure is a highly ordered array (i.e., a colloidal crystal) of colloidal spherical nanoparticles with a closely packed periodic structure. An inverse opal structure is a negative replica of an opal structure, in which solid spheres are replaced by voids forming pores and the spaces between the spheres are filled with a novel material. Opal or inverse opal structures have been used to construct microdevices to manipulate fluid behavior. As described herein, calcium carbonate or calcium magnesium carbonate is used to fill the voids in the opal structure. In the inverse opal structure, a 3D interconnected void network can generate nanoscale controllable porosity in a microfluidic pool, with the void size depending on the size of the colloidal sphere template used in fabrication. In one embodiment, a colloidal crystal with a closely packed opal structure has a spherical packing density of 70.5%, and therefore a porosity density of 70.5% in the inverse opal structure.

[0045] The fabrication method described above allows for the transformation of ordinary microfluidic cells into nanofluidic cells with nanoscale controllable porosity, and their silica or glass surfaces are also completely transformed into CaCO3 or CaMg(CO3)2. Nanofluidic cells can be used as micromodels with nanoscale porosity for carbonate reservoirs. Scanning electron micrographs are collected for confirmation.

[0046] Figures 9A-9B These are scanning electron micrographs of PS spheres 376 with a nanometer size of approximately 210 nm and calcium carbonate voids 378, respectively. The SEM images were taken using a scanning electron microscope (SEM, JEOL, JSM-7100F field emission) at 3–15 kV, without any additional coating applied to the sample surfaces.

[0047] While this specification contains numerous details of specific embodiments, these should not be construed as limiting the scope of what may be claimed, but rather as descriptions of features that may be specific to particular embodiments. Certain features described herein in the context of individual embodiments may also be implemented in combination in a single embodiment. Conversely, different features described in the context of a single embodiment may also be implemented individually or in any suitable sub-combination in multiple embodiments. Furthermore, although previously described features may be described as functioning in certain combinations and even initially claimed as such, in some cases, one or more features from the claimed combination may be removed from the combination, and the claimed combination may involve sub-combinations or variations of sub-combinations.

[0048] Specific embodiments of the subject matter have been described. Other embodiments, modifications, and arrangements of the described embodiments are within the scope of the appended claims and will be apparent to those skilled in the art. Although operations are depicted in a specific order in the drawings or claims, this should not be construed as requiring that such operations be performed in the specific order shown or in an ordered sequence, or requiring that all the operations shown can be performed (some operations may be considered optional) to achieve the desired result. In some cases, multitasking or parallel processing (or a combination of multitasking and parallel processing) may be advantageous and performed where deemed appropriate.

[0049] Therefore, the exemplary embodiments described above do not limit or restrict this disclosure. Other changes, substitutions, and modifications are possible without departing from the spirit and scope of this disclosure.

[0050] Several embodiments of these systems and methods have been described. However, it should be understood that various modifications can be made without departing from the spirit and scope of this disclosure. Therefore, other embodiments are within the scope of the appended claims.

Claims

1. A method for fabricating carbonate nanofluid structures with controllable nanoscale porosity for studying fluid behavior in underground oil reservoir environments, the method comprising: Synthesize multiple polymer spheres; The polymer spheres were purified in deionized water and then redispersed in a 1:1 water-ethanol mixture. The polymer spheres were arranged in a transparent flow cell; This initiates the crystallization of the multiple polymer spheres to form a template with an opal structure; The transparent flow cell was filled with calcium-based and carbonate-based solutions to form nanocrystals in the voids of the opal structure. Inverse opal structures of calcium carbonate or calcium magnesium carbonate are grown in opal structured templates. as well as The template formed by the crystallization of the multiple polymer spheres is removed from the transparent flow cell, leaving an inverse opal structure with multiple nano-sized pores and a carbonate surface.

2. The method as described in claim 1, wherein, The transparent flow cell has an optical path between 0.05 and 1 millimeter (mm) and a volume between 16 and 300 microliters (µL).

3. The method as described in claim 1, wherein, The multiple polymer spheres have dimensions between 50 and 1000 nanometers (nm).

4. The method of claim 1, further comprising crystallizing the plurality of polymer spheres in the transparent flow cell by drying at 60 degrees Celsius (°C) for 30 minutes.

5. The method of claim 1, wherein, This calcium-based solution further contains magnesium.

6. The method of claim 5, wherein, The formation of this calcium-based solution involves dissolving a solid CaCl2·2H2O solution in deionized water as a precursor for the formation of calcite.

7. The method of claim 5, wherein, The formation of this magnesium-containing calcium-based solution involves dissolving CaCl2·2H2O and MgCl2·6H2O solutions in deionized water at a molar ratio of 1:1, as a precursor for the formation of dolomite.

8. The method of claim 5, wherein, The formation of CaCO3 or CaMg(CO3)2 crystals in this transparent flow cell includes the addition of 1 M CO3 2- It is injected into the transparent flow cell to react with calcium- or magnesium-based ions.

9. The method of claim 8, wherein, Formation of 1 M CO3 2- This includes dissolving Na2CO3 or (NH4)2CO3 solution in deionized water.

10. The method of claim 8, further comprising mixing the calcium- or magnesium-based solution with the CO3 2- The solution was injected into the transparent flow cell and dried at 150°C for 2 hours to fill the voids of the transparent flow cell with the CaCO3 or CaMg(CO3)2 solution.

11. The method of claim 1, further comprising immersing the transparent flow cell in a toluene solution overnight and dissolving the plurality of polymer spheres.

12. The method of claim 11, further comprising injecting a solution of toluene, chloroform, or acetone into the transparent flow cell to wash the dissolved plurality of polymer spheres.

13. The method of claim 11, further comprising forming an inverse opal structure having multiple nanoscale pores by sintering the transparent flow cell at 280°C for 2 hours.

14. A method for fabricating carbonate nanofluid structures with controllable nanoscale porosity for studying fluid behavior in underground oil reservoir environments, the method comprising: Multiple polymer spheres are arranged in a transparent flow cell; This initiates the crystallization of the multiple polymer spheres to form a template with an opal structure; The transparent flow cell was filled with calcium-based and carbonate-based solutions to form nanocrystals in the voids of the opal structure. Inverse opal structures of calcium carbonate or calcium magnesium carbonate are grown in opal structured templates. The transparent flow cell was immersed in toluene solution overnight to dissolve the polymer spheres; and The template formed by the crystallization of the multiple polymer spheres is removed from the transparent flow cell, leaving an inverse opal structure with multiple nano-sized pores and a carbonate surface.

15. The method of claim 14, further comprising injecting a solution of toluene, chloroform, or acetone into the transparent flow cell to wash the dissolved plurality of polymer spheres.

16. The method of claim 14, further comprising forming an inverse opal structure having multiple nanoscale pores by sintering the transparent flow cell at 280°C for 2 hours.

17. The method of claim 14, wherein, The transparent flow cell has an optical path between 0.05 and 1 millimeter (mm) and a volume between 16 and 300 microliters (µL).

18. The method of claim 14, further comprising synthesizing the plurality of polymer spheres.

19. A carbonate nanofluid micromodel with nanoscale porosity, comprising: A transparent flow cell, the transparent flow cell including a first end defining an inlet and a second end defining an outlet; as well as The inverse opal structure in the transparent flow cell contains calcium carbonate with multiple nanoscale pores.

20. The model as described in claim 19, wherein, The second end includes a filter.

21. The model as described in claim 19, wherein, The transparent flow cell is a detachable quartz cell.

22. The model as described in claim 21, wherein, This transparent flow cell is also a microflow cell.

23. The model as described in claim 19, wherein, The anti-opal structure comprises a three-dimensional (3D) network with multiple interconnected voids.

24. The model as described in claim 23, wherein, These multiple interconnected voids have a characteristic size of controllable nanoscale between 50 and 1000 nm.

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