A method for making a triple medium carbonate reservoir micro-nanofluidic model

Abstract

The present invention provides a method for making a triple medium type carbonate reservoir micro-nanofluidic model, comprising the following steps: obtaining the cave structure, fracture structure, and pore structure of the carbonate core, and preparing a first mask, a second mask, and a third mask respectively; forming a photoresist layer on a glass substrate, sequentially exposing and etching the photoresist layer through a first mask, a second mask, and a third mask, and obtaining a first intermediate model after cleaning; laminating the first intermediate model with a glass substrate cover, and obtaining a second intermediate model after bonding; sequentially introducing a first solution, a second solution, and a third solution into the second intermediate model to form a calcium carbonate nanocrystalline layer to obtain a model. The method can simulate the real microscopic structural characteristics of carbonate rocks by reducing the triple medium structure of carbonate rocks and obtaining a triple medium type carbonate reservoir micro-nanofluidic model through continuous etching and in-situ modification.

Description

Technical Field

[0001] The invention belongs to the field of underground carbon storage technology and oil and gas field development technology, and specifically relates to a method for manufacturing a triple medium type carbonate reservoir micro-nanofluidic model. Background Art

[0002] Carbonate oil and gas occupy an important position in the world's oil and gas resource pattern, accounting for about 60%. The development of carbonate reservoirs can not only provide oil and gas energy, but also provide storage space for carbon dioxide. Therefore, carbonate reservoirs are a suitable choice for carbon dioxide recovery and geological storage. However, due to the complex diagenesis, reaction, sedimentation and deformation processes that produce multi-scale heterogeneity of the formation, resulting in complex underground flow behavior, carbonate reservoirs are often difficult to develop. In addition, carbonate reservoirs may also contain multi-scale natural fracture networks, which constitute complex cross-flow flow paths in the reservoir. Changes in matrix structure and fracture network connectivity are the main reasons why triple-medium carbonate reservoirs exhibit a variety of flow behaviors, resulting in great uncertainty in predicting carbon dioxide storage distribution and oil and gas recovery.

[0003] Traditional core models cannot observe the complex seepage characteristics and oil displacement laws in porous media. Micro-nanofluidic models are devices with transparent connected porous networks that can directly observe the complex fluid flow characteristics occurring inside. Since the 1950s, various two-dimensional micromodels have been established to study flow and transport phenomena in porous media. These studies are based on direct observation of pore-scale and / or macro-scale fluid structures, flow field visualization, and characterization of matrix-fluid interactions. These studies have important guiding significance for petroleum engineering, geological engineering, and environmental engineering.

[0004] When conducting micro-nanofluidic model oil recovery experiments, an important requirement is to invert the three-dimensional porous medium structure characteristics of the core into the micro-nanofluidic model so that the microstructure of the micro-nanofluidic model can represent the three-dimensional characteristics of the real core. The current micro-nanofluidic model mainly adopts the array structure of the regular model, which has problems such as being unable to fully simulate the three-dimensional structural characteristics of the real core; some micro-nanofluidic models refer to the characteristics of two-dimensional core slices and cannot reflect the three-dimensional connectivity of porous media. The current microfluidic design ignores the three-dimensional structural characteristics of the real core, which seriously restricts the application and development of micro-nanofluidic models in the field of oil and gas development. Summary of the invention

[0005] The present invention provides a method for preparing a triple-medium carbonate reservoir micro-nanofluidic model. The method reduces the triple-medium structure of carbonate rock and obtains the triple-medium carbonate reservoir micro-nanofluidic model by continuous etching and in-situ modification, thereby simulating the real microstructural characteristics of carbonate rock.

[0006] In a first aspect of the present invention, a method for making a triple medium carbonate reservoir micro-nanofluidic model is provided, comprising the following steps:

[0007] The karst cave structure, fracture structure and pore structure of the carbonate rock core are obtained, and a first mask, a second mask and a third mask are prepared respectively; wherein the first mask has a karst cave structure, the second mask has a fracture structure and a karst cave structure, and the third mask has a karst cave structure, a fracture structure and a pore structure;

[0008] Forming a photoresist layer on a glass substrate, sequentially exposing and etching the photoresist layer through a first mask, a second mask, and a third mask, and obtaining a first intermediate model after cleaning;

[0009] Laminating one side of the first intermediate model etched with a glass base cover plate, and obtaining a second intermediate model after bonding treatment;

[0010] The first solution, the second solution and the third solution are sequentially introduced into the second intermediate model to form a calcium carbonate nanocrystalline layer, thereby obtaining a triple medium type carbonate reservoir micro-nanofluidic model; wherein the first solution contains sodium salt of N-(trimethoxysilylpropyl)ethylenediaminetriacetic acid, and the second solution contains Ca 2+ , the third solution contains CO3 2- .

[0011] The manufacturing method as described above further includes the following steps: introducing crude oil and water into the triple medium type carbonate reservoir micro-nanofluidic model in sequence for a first flushing treatment, and after aging and drying treatments, changing the model from water-wet characteristics to oil-wet characteristics; or, introducing paraffin solution, crude oil, and water into the triple medium type carbonate reservoir micro-nanofluidic model in sequence for a first flushing treatment, and after aging and drying treatments, changing the model from water-wet characteristics to mixed wetting characteristics.

[0012] In the above-mentioned production method, the process of obtaining the cave structure, fracture structure and pore structure of the carbonate rock core includes the following steps:

[0013] A triple medium carbonate rock core was selected and made into a cylindrical rock sample after deoiling and drying;

[0014] Performing tomography imaging on the rock sample to obtain the cave structure and fracture structure of the carbonate rock core;

[0015] The pore structure of the rock sample was obtained using cast thin sections and scanning electron microscopy.

[0016] The manufacturing method as described above, wherein, before coating the photoresist on the glass substrate, further comprises the following steps: placing the glass substrate in a solution containing a surfactant for ultrasonic treatment.

[0017] In the manufacturing method as described above, the photoresist layer is at least one layer; preferably, the photoresist layer is two layers.

[0018] In the manufacturing method as described above, the etching process is at least one of wet etching and inductively coupled plasma etching.

[0019] The manufacturing method as described above, wherein a first photoresist layer is formed on a glass substrate, the first photoresist layer is subjected to a first exposure process and a first etching process through a first mask, and a first etching pattern is obtained after a first cleaning process;

[0020] forming a second photoresist layer on the first etching model, performing a second exposure process and a second etching process on the second photoresist layer through a second mask, and obtaining a second etching model after a second cleaning process;

[0021] forming a third photoresist layer on the second etching model, performing a third exposure process and a third etching process on the third photoresist layer through a third mask, and obtaining a first intermediate model after a third cleaning process;

[0022] The first etching process and the second etching process are wet etching respectively, and the third etching process is inductively coupled plasma etching.

[0023] The manufacturing method as described above, wherein the etched side of the first intermediate model is stacked with a glass-based cover sheet to obtain a model to be bonded, the model to be bonded is stacked between two graphite sheets, a steel plate or a corundum plate is placed on the side of the two graphite sheets away from the model to be bonded, and the two graphite sheets are horizontally placed in a muffle furnace for the bonding process;

[0024] Wherein, the bonding treatment is performed at a temperature of 400 to 700° C. and for a time of 4 to 12 hours.

[0025] The manufacturing method as described above, wherein, further includes the following steps: drilling holes at both ends of the second intermediate model to form an injection port and a production port, and sequentially introducing the first solution, the second solution, and the third solution through the injection ports.

[0026] In the above-mentioned manufacturing method, the thickness of the calcium carbonate nanocrystalline layer is 0.5-4 μm.

[0027] The implementation of the present invention has at least the following beneficial effects:

[0028] (1) The method for making the triple-medium carbonate reservoir micro-nanofluidic model provided by the present invention can simulate the triple medium structure of the cave structure, fracture structure, and pore structure inside the carbonate, thereby improving the accuracy of simulating the seepage of the real carbonate reservoir and facilitating the study of the relationship between pores, fractures, and caves in carbonate rocks.

[0029] (2) The present invention makes the etching depth of the triple medium structure controllable through continuous etching, thereby solving the problem of uncontrollable depth in the prior art; and the present invention reflects the difference in the vertical conductivity of the triple medium structure through the different etching depths of the structure, thereby improving the accuracy of simulating the seepage of real carbonate reservoirs.

[0030] (3) The method for making a triple medium carbonate reservoir micro-nanofluidic model provided by the present invention. In the prior art, the microchannels of the fluidic model are usually made of glass or other smooth materials. The surface roughness of these materials is quite different from that of the actual carbonate reservoir, and they are water-wet. The present invention can more accurately simulate the natural roughness of the surface of the carbonate reservoir by forming a structure with a calcium carbonate nanocrystal layer in the microchannel, thereby providing a more realistic model for studying the flow of oil and gas in the reservoir. The present invention forms a calcium carbonate nanocrystal layer on the surface of the microchannel, so that the wettability of the model is closer to that of the actual carbonate reservoir, so that the flow characteristics of oil and gas in this environment can be more accurately studied. The method for making this triple medium carbonate reservoir micro-nanofluidic model forms a calcium carbonate nanocrystal layer in the microchannel by an in-situ modification method, which not only truly reflects the roughness of the carbonate reservoir surface, but also simulates its oil-wetting wetting characteristics, which is of great significance for in-depth research on the oil and gas flow mechanism in the carbonate reservoir and improving the efficiency of oil and gas production.

[0031] (4) The preparation method of the present invention is simple to operate and has low cost. The triple-medium carbonate reservoir micro-nanofluidic model prepared by the preparation method can withstand the harsh conditions of high temperature (300°C) and high pressure (70MPa), and has a wide range of applications. It is helpful to study the transport process in the porous medium of carbonate reservoirs and the seepage law of the three phases of oil, gas and water under different solid-liquid and solid-liquid-gas conditions, and the model can be reused.

[0032] The present invention has demonstrated remarkable uniqueness in the field of underground carbon sequestration, focusing on large-scale CO2 sequestration using geological structures such as carbonate rocks. By adopting a micro-nanofluidic model of triple-medium carbonate reservoirs, the present invention can simulate the complex rock properties, pore characteristics and heterogeneity of the underground, and realize the visualization study of CO2 interface phenomena and multiphase flow laws in underground porous media after CO2 injection. This technology can not only efficiently monitor and evaluate the utilization and storage effects of CO2, but also provide important guidance for numerical simulation optimization and field operations of large-scale geological storage, thereby optimizing the application of carbon sequestration technology in underground storage. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a flow chart of a method for making a triple medium carbonate reservoir micro-nanofluidic model in one embodiment of the present invention;

[0034] Figure 2 is a front view of a first etching model of Example 1 of the present invention;

[0035] Figure 3 is a schematic diagram of the first etching model in Example 1 of the present invention;

[0036] Figure 4 is a front view of a second etching model of Example 1 of the present invention;

[0037] Figure 5 is a schematic diagram of the second etching model in Example 1 of the present invention;

[0038] Figure 6 is a front view of a first intermediate model of Example 1 of the present invention;

[0039] Figure 7 is a schematic diagram of the first intermediate model in Example 1 of the present invention;

[0040] Figure 8 is a schematic diagram of the reaction process of in-situ modification to form a calcium carbonate nanocrystalline layer in one embodiment of the present invention;

[0041] Fig. 9 is a bar graph of the water contact angle of the model in Example 1 of the present invention;

[0042] Fig.10 It is a bar graph of the water contact angle of the model in Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] like Figure 1 As shown, in the first aspect of the present invention, a method for making a triple medium type carbonate reservoir micro-nanofluidic model is provided, comprising the following steps: obtaining the cave structure, fracture structure, and pore structure of the carbonate core, and preparing a first mask, a second mask, and a third mask respectively; wherein the first mask has a cave structure, the second mask has a fracture structure and a cave structure, and the third mask has a cave structure, a fracture structure, and a pore structure; forming a photoresist layer on a glass substrate, and sequentially performing the first and second steps of the photoresist layer on the glass substrate; The first mask, the second mask and the third mask are exposed and etched, and a first intermediate model is obtained after cleaning; the etched side of the first intermediate model is bonded to a glass-based cover plate, and a second intermediate model is obtained after bonding; the first solution, the second solution and the third solution are sequentially introduced into the second intermediate model to form a calcium carbonate nanocrystalline layer, and a triple medium carbonate reservoir micro-nanofluidic model is obtained; wherein the first solution contains N-(trimethoxysilylpropyl)ethylenediaminetriacetic acid sodium salt, and the second solution contains Ca 2+ , the third solution contains CO3 2- .

[0045] It should be noted that the diameter of the pore structure of the present invention is less than 100 μm, the opening of the fracture structure is greater than or equal to 100 μm, and the diameter of the cave structure is greater than 2 mm.

[0046] After obtaining the cave structure, fracture structure and pore structure of the carbonate rock core, the obtained cave structure, fracture structure and pore structure are drawn to generate a mask pattern that can be recognized by the lithography equipment (specifically, it can be calibrated to an image resolution of 1 μm per pixel). According to the different patterns, the mask pattern is divided into a first mask pattern, a second mask pattern and a third mask pattern, wherein the first mask pattern includes a pattern of the cave structure, the second mask pattern includes patterns of the fracture structure and the cave structure, and the third mask pattern includes patterns of the cave structure, the fracture structure and the pore structure.

[0047] It should be noted that after obtaining the pore structure, crack structure, and cave structure from the micron scale to the nanoscale, it is also necessary to construct the connectivity of the pore structure, crack structure, and cave structure to obtain a second mask pattern having both crack structure and cave structure patterns and a third mask pattern having both cave structure, crack structure, and pore structure patterns.

[0048] The patterns on the first mask pattern, the second mask pattern, and the third mask pattern are transferred to the mask material to form the first mask, the second mask, and the third mask, so that the first mask has a cave structure, the second mask has a crack structure and a cave structure, and the third mask has a cave structure, a crack structure, and a pore structure. The preparation of the first mask, the second mask, and the third mask can be carried out using conventional photolithography equipment in the art.

[0049] A photoresist is coated on a glass substrate to form a photoresist layer on the glass substrate, and the photoresist layer is stacked with the glass substrate. The photochemical reaction of the photoresist is utilized to transfer the pattern on the mask from the mask to the photoresist layer during the exposure process. Under the action of a developer, part of the photoresist layer will dissolve, exposing part of the glass substrate, and the remaining photoresist layer will remain. The etching process is essentially to etch the exposed part of the glass substrate. Under the action of an etching solution, the part of the glass substrate that is not protected by the photoresist layer will be corroded and dissolved to a certain depth to form a graphic area, while the remaining glass substrate protected by the photoresist layer will remain in its original state, which can also be called a non-graphic area. At this time, the remaining photoresist layer is removed by a cleaning process, so that the pattern of the mask is transferred to the glass substrate.

[0050] The glass substrate has two largest and opposite functional surfaces, and the photoresist layer is disposed on one of the functional surfaces. The photoresist may be a conventional photoresist in the art, as long as the photoresist has good tolerance during etching and does not separate from the surface of the glass substrate.

[0051] Since the first mask has a cave structure, the second mask has a crack structure and a cave structure, and the third mask has a cave structure, a crack structure, and a pore structure, in the process of sequentially performing exposure processing and etching processing through the first mask, the second mask, and the third mask, the first exposure processing and the first etching processing can be performed through the first mask first, and then the second exposure processing and the second etching processing are performed through the second mask, and finally the third exposure processing and the third etching processing are performed through the third mask. In other words, the corresponding cave structure position on the glass substrate is actually etched three times, the crack structure position is actually etched twice, and the pore structure position is actually etched once. At this time, the etching depth of the cave structure position> the etching depth of the crack structure position> the etching depth of the pore structure position. The reason for the arrangement of the present invention is that pores, cracks and caves have obvious differences in pore size, length and shape, and their storage capacity and seepage capacity are also different. Selecting different etching depths for different seepage media can further enhance the difference in seepage capacity of different media, which is conducive to better reflecting the topological relationship, connectivity and conductivity of different porous media structures in the triple-medium type carbonate reservoir micro-nanofluidic model.

[0052] The cleaning process mainly uses a cleaning solution to remove impurities such as the residual photoresist layer and the etching solution, and finally obtains the first intermediate model after the cleaning process.

[0053] Among them, the functional surface of the glass substrate plate provided with a photoresist layer is etched to form a cave structure, a crack structure and a pore structure with a certain etching depth, and the functional surface with these structures constitutes one side of the etching of the first intermediate model.

[0054] The etched side of the first intermediate model (also referred to as the side with the graphic area) is bonded to the glass base cover sheet, which can also be understood as the first intermediate model and the glass base cover sheet are stacked, and the side of the first intermediate model with the graphic area is arranged opposite to a surface of the glass base cover sheet. Since the graphic area of ​​the first intermediate model has a certain depth, it is actually the non-graphic area of ​​the first intermediate model that is bonded to the surface of the glass base cover sheet. The glass base cover sheet and the glass base plate have the same size.

[0055] The first intermediate model and the glass base cover are bonded to each other so that the non-graphic area of ​​the first intermediate model and the glass base cover are closely bonded to form a whole, thereby obtaining a second intermediate model. At this time, the graphic area in the first intermediate model and the glass base cover form a channel of the second intermediate model.

[0056] The first solution, the second solution, and the third solution are sequentially introduced into the second intermediate model, which is essentially the case that the first solution, the second solution, and the third solution are sequentially introduced into the channel of the second intermediate model, that is, a calcium carbonate nanocrystalline layer is formed on the surface of the microchannel, wherein the first solution contains N-(trimethoxysilylpropyl)ethylenediaminetriacetic acid sodium salt, and the second solution contains Ca 2+ , the third solution contains CO3 2- Since the surface of the glass substrate contains a large number of hydroxyl groups, such as Figure 8 As shown in (a), the microchannel surface of the second intermediate model also contains a large number of hydroxyl groups. After the first solution is introduced, the methoxyl groups of N-(trimethoxysilylpropyl)ethylenediaminetriacetic acid sodium salt undergo hydrolysis reaction to form silanol, and the silanol and carboxylic acid groups undergo condensation reaction to form oligomers. The hydroxyl groups on the oligomers are combined with the hydroxyl groups on the second intermediate model through hydrogen bonds, and then covalent bonds are formed through dehydration condensation to obtain a surface with COO - The second intermediate model of the group; after the second solution is introduced, Figure 8 As shown in (b), COO - Group and Ca 2+ Combine to form a precursor layer; after the third solution is introduced, Figure 8 As shown in (c) and (d), Ca 2+ With CO3 2- Combined to form a CaCO3 nanocrystalline layer. The CaCO3 nanocrystalline layer can stably adhere to the channel of the second intermediate model, thereby forming a microchannel with an uneven surface, and through in-situ synthesis, the CaCO3 nanocrystals can be randomly arranged on the surface of the microchannel, restoring the rough surface of the real carbonate reservoir, reflecting the wettability of the real carbonate reservoir surface, which is conducive to better simulation of the real carbonate reservoir environment.

[0057] According to the research of the present invention, the method can simulate the real microstructural characteristics of carbonate rocks. This is because, on the one hand, the present invention can not only simulate the triple medium structure of the cave structure, fracture structure, and pore structure inside the carbonate through continuous etching, but also can reflect the differential simulation of the vertical conductivity of the triple medium structure through the etching depth, thereby improving the accuracy of simulating the seepage of the real carbonate reservoir. On the other hand, the present invention forms a microchannel with a calcium carbonate nanocrystalline layer through an in-situ modification method, which can truly reflect the roughness and wetting characteristics of the carbonate reservoir surface. Therefore, the preparation method provided by the present invention can simulate the real microstructural characteristics of carbonate rocks through the above two aspects and improve accuracy.

[0058] The method of flushing the microchannels in the triple medium type carbonate reservoir micro-nanofluidic model of the present invention by solution can flexibly perform wetting modification on the microchannels in the model to form a water-wet, oil-wet or mixed-wet model, so that the microchannels in the model are more in line with the oil and gas migration channels in the actual reservoir. In some embodiments, the following steps are also included: crude oil and water are sequentially introduced into the triple medium type carbonate reservoir micro-nanofluidic model for a first flushing treatment, and after drying, the model is changed from water-wet characteristics to oil-wet characteristics; or, paraffin solution, crude oil, and water are sequentially introduced into the triple medium type carbonate reservoir micro-nanofluidic model for a first flushing treatment, and after drying, the model is changed from water-wet characteristics to mixed wetting characteristics.

[0059] In the first flushing process, the liquid is introduced into the microchannels in the model in sequence. The model is wetted and modified by the flushing process. After the flushing process, a drying process is required to eliminate the influence of the residual liquid.

[0060] In the specific implementation process of the present invention, crude oil is injected into the triple medium type carbonate reservoir micro-nanofluidic model, which is then placed in a 60°C oven and taken out after 24 hours; the injected crude oil is rinsed with clean water, and the surface of the obtained model becomes an oil-wet surface, reflecting the water-wet characteristics of the oil layer; in addition, a molten paraffin solution can be first injected into the triple medium type carbonate reservoir micro-nanofluidic model to block part of the microchannels of the model, and then crude oil is injected, the model is placed in an oven, taken out after aging for 24 hours, and the residual paraffin and crude oil in the model are washed with clean water, and the surface of the obtained model is converted into a mixed wetting surface.

[0061] The present invention does not limit the method of obtaining the triple medium structure, and it can be obtained by conventional methods in the field. For example, a desktop CNC milling machine can be used to carve out the triple medium structure, or a photolithography technique can be used to obtain the triple medium structure. In some embodiments, the process of obtaining the cave structure, fracture structure, and pore structure of a carbonate rock core includes the following steps: selecting a triple medium carbonate rock core, degreasing, and drying it, and making it into a cylindrical rock sample; performing tomography imaging on the rock sample to obtain the cave structure and fracture structure of the carbonate rock core; using a cast thin section and a scanning electron microscope to obtain the pore structure of the rock sample, that is, the pore structure of the carbonate rock core.

[0062] Furthermore, a triple-medium carbonate rock core can be selected and made into two cylindrical rock samples, namely the first section rock sample and the second section rock sample; the first section rock sample is subjected to tomography imaging to obtain the cave structure and fracture structure of the carbonate rock core; and the pore structure of the second section rock sample is obtained using cast thin sections and scanning electron microscopes.

[0063] The present invention also includes scanning the interconnectedness in the rock sample using a scanning electron microscope, and reconstructing the interconnectedness structure obtained by scanning to distinguish the pore-cavity-crack triple medium structure, specifically to obtain the morphological characteristics, size parameters and interconnectedness of the pore structure, cave structure and crack structure with high definition.

[0064] By pre-treating the glass substrate, the influence of impurities on the surface of the glass substrate on the model is avoided. In some embodiments, before coating the photoresist on the glass substrate, the following steps are also included: placing the glass substrate in a solution containing a surfactant for ultrasonic treatment. The ultrasonic treatment time can be 5 minutes, and the impurities on the surface of the glass substrate are removed by ultrasonic treatment to avoid the influence of impurities on subsequent model making.

[0065] The present invention does not limit the number of photoresist layers, and can be adjusted according to actual needs. In some embodiments, the photoresist layer is at least one layer; preferably, the photoresist layer is two layers. When the photoresist layer is two layers, a first layer of photoresist can be coated on the glass substrate first, and then a second layer of photoresist can be coated after heating, and a two-layer photoresist layer can be formed after heating.

[0066] The present invention does not limit the specific operation steps of the etching process, which may be chemical etching, physical etching, or physical and chemical etching. The etching process is to etch the exposed part of the glass substrate, so as to transfer the pattern on the mask to the glass substrate. In some embodiments, the etching process is at least one of wet etching and inductively coupled plasma etching.

[0067] Among them, wet etching is a traditional etching method, which allows the exposed part of the glass substrate to react chemically with chemical reagents and be removed. Wet etching is simple to operate, has low equipment requirements, is easy to achieve mass production, and has good etching selectivity. However, it is difficult to accurately control the pattern in wet etching. Inductively coupled plasma etching uses molecules or molecular groups that react ionically with the exposed part of the glass substrate to generate volatile reaction products, thereby achieving etching. Inductively coupled plasma etching can have good etching selectivity and high etching rate, and can control etching accuracy, but the efficiency is low.

[0068] The present invention selects different etching methods according to the structural characteristics of the triple medium, which is conducive to better simulation of real carbonate oil reservoirs. In some embodiments, a first photoresist layer is formed on a glass substrate, and the first photoresist layer is subjected to a first exposure process and a first etching process through a first mask, and a first etching model is obtained after a first cleaning process; a second photoresist layer is formed on the first etching model, and the second photoresist layer is subjected to a second exposure process and a second etching process through a second mask, and a second etching model is obtained after a second cleaning process; a third photoresist layer is formed on the second etching model, and the third photoresist layer is subjected to a third exposure process and a third etching process through a third mask, and a first intermediate model is obtained after a third cleaning process; wherein, the first etching process and the second etching process are respectively wet etching, and the third etching process is inductively coupled plasma etching. This is because the pore structure is mostly micro-nano pores, and the use of inductively coupled plasma etching is conducive to the formation of a nanoscale matrix, and by combining wet etching and inductively coupled plasma etching, it is conducive to taking into account both accuracy and efficiency.

[0069] The present invention does not limit the specific operation steps of the bonding process, and conventional bonding methods in the art can be used. In some embodiments, one side of the first intermediate model etched is stacked with a glass-based cover sheet to obtain a model to be bonded, and the model to be bonded is stacked between two graphite sheets, and a steel plate or a corundum plate is placed on the side of the two graphite sheets away from the model to be bonded, and the two graphite sheets are horizontally placed in a muffle furnace for bonding treatment; wherein the bonding treatment temperature is 400 to 700°C, and the time is 4 to 12 hours.

[0070] Among them, the present invention does not impose too many restrictions on the specific dimensions of the glass substrate plate and the glass-based cover plate, which can be adjusted based on actual conditions. For example, in some embodiments, the length and width of the glass substrate plate and the glass-based cover plate are 4.5 cm respectively, and the total thickness of the glass substrate plate and the glass-based cover plate is 0.8 to 2 cm.

[0071] Introducing the solution into the second intermediate model is essentially passing the solution into the channel of the second intermediate model. In some embodiments, the first solution, the second solution, and the third solution are sequentially introduced through the injection port. The injection port and the extraction port are respectively arranged on opposite sides of the first intermediate model and are connected to the channel. Among them, the punching process can be performed using equipment such as a puncher. The opening size of the injection port and the extraction port is related to the size of the glass substrate plate and can be determined according to actual conditions. For example, the opening size can be circular with a diameter of 2 to 3 mm.

[0072] The present invention does not limit the thickness of the calcium carbonate nanocrystal layer. For example, in some embodiments, the thickness of the calcium carbonate nanocrystal layer is 0.5-4 μm.

[0073] By controlling the dosage of the first solution, the second solution, and the third solution and the reaction time and other parameters, the packing density of CaCO3 nanocrystals on the microchannel surface can be adjusted, thereby adjusting the thickness of the calcium carbonate nanocrystal layer to achieve the purpose of controllable surface roughness of the microchannel.

[0074] The triple medium carbonate reservoir micro-nanofluidic model prepared by the above-mentioned manufacturing method can be directly used in seepage experiments, which is helpful to understand the seepage law of triple medium carbonate rocks, especially the microscopic seepage law of oil, gas and water three-phase under various conditions. The model of the present invention can withstand the pressure within 10MPa of the internal and external pressure difference, and can withstand 70MPa of pressure by cooperating with the confining pressure loading system; therefore, the model of the present invention can withstand the harsh conditions of high temperature (300℃) and high pressure (70MPa), has wide adaptability, and can meet the requirements of most reservoir environments.

[0075] The present invention will be further described below by means of specific examples and comparative examples.

[0076] Example 1

[0077] The method for making a triple medium carbonate reservoir micro-nanofluidic model comprises the following steps:

[0078] (1) Real carbonate reservoir cores from Shengli Oilfield were selected and scanned using micro-nano CT, cast thin sections, and scanning electron microscope imaging techniques to obtain pore structures, fracture structures, and cave structures from micrometer to nanometer scales;

[0079] (2) analyzing the topological relationship of the pore structure, fracture structure, and karst cave structure through the obtained three-dimensional data of the carbonate core, designing the shape and depth of the pore structure, fracture structure, and karst cave structure, and constructing the three-dimensional structure of the carbonate core and the connectivity relationship of the three-media; and correspondingly designing the first mask pattern, the second mask pattern, and the third mask pattern, wherein the first mask pattern includes the pattern of the karst cave structure, the second mask pattern includes the pattern of the fracture structure and the karst cave structure, and the third mask pattern includes the pattern of the karst cave structure, the fracture structure, and the pore structure;

[0080] (3) transferring the patterns on the first mask pattern, the second mask pattern, and the third mask pattern to the mask material to form the first mask, the second mask, and the third mask;

[0081] A first photoresist layer is formed on a glass substrate, and a first exposure process and a first etching process are performed on the first photoresist layer through a first mask. After a first cleaning process, a first etching pattern (such as Figure 2 and Figure 3 shown);

[0082] A second photoresist layer is formed on the first etching model, and the second photoresist layer is subjected to a second exposure process and a second etching process through a second mask, and a second etching model (such as Figure 4 and Figure 5 shown);

[0083] A third photoresist layer is formed on the second etched model, and the third photoresist layer is subjected to a third exposure process and a third etching process through a third mask. After a third cleaning process, a first intermediate model (such as Figure 6 and Figure 7 shown);

[0084] Wherein, the first etching process and the second etching process are respectively wet etching, and the third etching process is inductively coupled plasma etching;

[0085] (4) Aligning the etched side of the first intermediate model with the glass base cover, exhausting the air, and then removing the moisture by heating to obtain the model to be bonded; stacking the model to be bonded between two graphite sheets, placing a steel plate or a corundum plate on the side of the two graphite sheets away from the model to be bonded, and placing them horizontally in a muffle furnace for bonding treatment, so that the non-graphic area of ​​the first intermediate model and the glass base cover are tightly bonded together through bonding; after the bonding is completed, the stress is released by annealing method to obtain the second intermediate model, wherein the temperature of the bonding treatment is 500h and the time is 5h;

[0086] (5) The second intermediate model is taken out, and holes are punched at both ends of the second intermediate model to form an injection port and a production port, and the first solution, the second solution, and the third solution are sequentially introduced through the injection port to form a calcium carbonate nanocrystalline layer, thereby obtaining a triple medium type carbonate reservoir micro-nanofluidic model; wherein the first solution contains N-(trimethoxysilylpropyl)ethylenediaminetriacetic acid sodium salt, the second solution contains CaCl2, and the third solution contains Na2CO3.

[0087] Comparative Example 1

[0088] The preparation process is basically the same as that of Example 1, except that steps (4) and (5) are omitted, and the first intermediate model is directly used as the model of this comparative example.

[0089] According to the methods of the above-mentioned Example 1 and Comparative Example 1, 10 sample models were prepared, and clean water was dropped on the etched surface of the model respectively, and the contact angles between the water droplet and the etched surface were measured. The test results are as follows: Fig. 9 (Example 1) and Fig.10 (Comparative Example 1) is shown.

[0090] according to Fig. 9 and Fig.10It can be seen that the present invention forms a calcium carbonate nanocrystalline layer on the surface of the microchannel, so that the wettability of the model is closer to the actual carbonate reservoir, so that the flow characteristics of oil and gas in this environment can be studied more accurately.

[0091] This embodiment provides the following multiple ways to use the triple medium carbonate reservoir micro-nanofluidics model to simulate CO2 storage implementation:

[0092] Case 1: The oil-wet micro-nanofluidic model is placed at reservoir temperature and pressure and saturated with crude oil. Supercritical CO2 is injected from the injection port to simulate the injection well, and the CO2 seepage path is observed. The fluid distribution is observed through an optical microscope. The effect of reservoir heterogeneity on CO2 storage under the influence of oil-wet is explored.

[0093] Case 2: Place the mixed wetting micro-nanofluidic model at reservoir temperature and pressure and saturate it with crude oil, inject supercritical CO2 from the injection port, simulate the injection well, observe the CO2 seepage path, and observe the fluid distribution through an optical microscope. Explore the impact of reservoir heterogeneity on CO2 storage under the influence of mixed wetting.

[0094] The preferred specific embodiments and experimental verification of the present invention are described in detail above. It should be understood that ordinary technicians in this field can make many modifications and changes based on the concept of the present invention without creative work. Therefore, all technical solutions that can be obtained by technicians in this technical field based on the concept of the present invention through logical analysis, reasoning or limited experiments on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A method for making a triple medium carbonate reservoir micro-nanofluidic model, characterized in that: The following steps are involved: The karst cave structure, fracture structure and pore structure of the carbonate rock core are obtained, and a first mask, a second mask and a third mask are prepared respectively; wherein the first mask has a karst cave structure, the second mask has a fracture structure and a karst cave structure, and the third mask has a karst cave structure, a fracture structure and a pore structure; A photoresist layer is formed on a glass substrate, and the photoresist layer is exposed and etched through a first mask, a second mask, and a third mask in sequence so that the etching depth of the corresponding cave structure position on the glass substrate is greater than the etching depth of the crack structure position, and the etching depth of the crack structure position is greater than the etching depth of the pore structure position, and a first intermediate model is obtained after cleaning; wherein the corresponding cave structure position on the glass substrate is etched three times, the crack structure position is etched twice, and the pore structure position is etched once; the method adopts three etchings, the first two etchings are wet etching, and the third etching is inductively coupled plasma etching; The etched side of the first intermediate model is stacked with a glass-based cover sheet to obtain a model to be bonded, the model to be bonded is stacked between two graphite sheets, a steel plate or a corundum plate is placed on the side of the two graphite sheets away from the model to be bonded, and the two graphite sheets are horizontally placed in a muffle furnace for bonding treatment to obtain a second intermediate model; wherein the bonding treatment temperature is 400 to 700° C., and the time is 4 to 12 hours; The first solution, the second solution and the third solution are sequentially introduced into the second intermediate model to form a calcium carbonate nanocrystalline layer, thereby obtaining a triple medium type carbonate reservoir micro-nanofluidic model; wherein the first solution contains sodium salt of N-(trimethoxysilylpropyl)ethylenediaminetriacetic acid, and the second solution contains Ca 2+ , the third solution contains CO3 2- .

2. The method according to claim 1, characterized in that: The following steps are also included: Crude oil and water are sequentially introduced into the triple-medium carbonate reservoir micro-nanofluidic model for a first flushing treatment, and after aging and drying treatment, the model is changed from water-wet characteristics to oil-wet characteristics; or, paraffin solution, crude oil and water are sequentially introduced into the triple-medium carbonate reservoir micro-nanofluidic model for a first flushing treatment, and after drying treatment, the model is changed from water-wet characteristics to mixed wetting characteristics or oil-wet characteristics.

3. The method according to claim 1, characterized in that: The process of obtaining the cave structure, fracture structure, and pore structure of carbonate rock cores includes the following steps: A triple medium carbonate rock core was selected and made into a cylindrical rock sample after deoiling and drying; Performing tomography imaging on the rock sample to obtain the cave structure and fracture structure of the carbonate rock core; The pore structure of the rock sample was obtained using cast thin sections and scanning electron microscopy.

4. The method according to claim 1, characterized in that: Before coating the photoresist on the glass substrate, the method further comprises the following steps: placing the glass substrate in a solution containing a surfactant for ultrasonic treatment.

5. The method according to claim 1, characterized in that: The photoresist layer is at least one layer.

6. The method according to claim 5, characterized in that: The photoresist layer consists of two layers.

7. The manufacturing method according to claim 1, characterized in that: The method comprises forming a photoresist layer on a glass substrate, and sequentially performing exposure processing and etching processing on the photoresist layer through a first mask, a second mask, and a third mask, including: Forming a first photoresist layer on a glass substrate, performing a first exposure process and a first etching process on the first photoresist layer through a first mask, and obtaining a first etching pattern after a first cleaning process; forming a second photoresist layer on the first etching model, performing a second exposure process and a second etching process on the second photoresist layer through a second mask, and obtaining a second etching model after a second cleaning process; forming a third photoresist layer on the second etched model, performing a third exposure process and a third etching process on the third photoresist layer through a third mask, and obtaining a first intermediate model after a third cleaning process; The first etching process and the second etching process are wet etching respectively, and the third etching process is inductively coupled plasma etching.

8. The manufacturing method according to claim 1, characterized in that: Holes are punched at both ends of the first intermediate model to form an injection port and a production port.

9. The manufacturing method according to claim 8, characterized in that: The method also includes the following steps: sequentially introducing the first solution, the second solution, and the third solution through the injection port.

10. The manufacturing method according to claim 1, characterized in that: The thickness of the calcium carbonate nanocrystalline layer is 0.5-4 μm.

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