Photo-thermal conversion type nano material, preparation method thereof and seepage chart construction method

Abstract

The invention belongs to the technical field of improvement of crude oil recovery efficiency, and particularly relates to a photo-thermal conversion type nano material, a preparation method thereof and a seepage chart construction method. The photo-thermal conversion type nano material comprises a silver selenide nano crystal nucleus, a silver selenide nano crystal nucleus and a silver selenide nano crystal The surface of the silver selenide nanocrystal nucleus is coated with the composite layer; wherein the composite layer is selected from (i) a composite layer of a first chemical ligand and a second chemical ligand; or (ii) a composite layer of a microorganism or extract and a biosurfactant. The photo-thermal conversion type nano material has tracing and oil displacement capabilities, can be used for carrying out laboratory oil displacement evaluation experiments and establishing a distribution model of nano particles in a core pore throat, can also be applied on site, and can be used as a chemical oil displacement agent to assist efficient development of offshore crude oil.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of enhanced oil recovery, and particularly relates to a photo-thermal conversion type nanomaterial, a preparation method thereof and a percolation chart construction method. BACKGROUND

[0002] With the rapid growth of global energy demand, oil as an important energy resource plays an increasingly important role in industrial production and daily life. However, traditional oil extraction technology faces a series of challenges in long-term application, including decreased recovery rate in the later stage of reservoir development, increased production cost and environmental pollution. Therefore, developing new efficient and environmentally friendly oil extraction technology has become an important research direction in the field of oil industry.

[0003] In recent years, nanomaterials have attracted widespread attention due to their unique physical and chemical properties, especially in terms of high specific surface area, superior chemical stability and functional modification capabilities. In the oil industry, nanomaterials are considered as an emerging technology for enhanced oil recovery. These materials have small size, good solubility and compatibility, large specific surface area and surface energy, which can reduce the injection pressure of agents, reduce the oil-water interfacial tension, and improve the reservoir permeability. Photo-thermal conversion type nanomaterials are a kind of functional materials that can absorb light energy and efficiently convert it into heat energy. This material usually has excellent light absorption performance and can achieve high-efficiency heat conversion in a specific wavelength range (such as visible light, near-infrared light or ultraviolet light). By relying on its photo-thermal conversion characteristics, the distribution state of nanomaterials in core pores can be characterized, and a core pore model can be established. It can also be used to characterize the distribution of residual oil in the core.

[0004] The modification of nanomaterials is crucial for the lipophilicity of agents, compatibility with formation water, and other aspects. The physicochemical properties of nanomaterials have certain relationship with the type and quantity of surface ligands. Therefore, by changing the surface ligands, the physicochemical properties of nanomaterials such as wettability, solubility, and emulsifying properties can be changed. This can not only endow nanomaterials with emulsifying, oil washing, and viscosity reducing functional properties, but also improve their compatibility with formation water or other agents, which helps to expand their application range and make them suitable for formation environment.

[0005] For example, the Chinese invention patent with publication number CN118909610A discloses a kind of nano oil displacement agent and its preparation method, potassium sorbate and nanoparticle are added to mesoporous SiO2, make particle embed in the pore of SiO2, then add fatty alcohol polyoxyethylene ether phosphate monoester and trehalose lipid to form nano oil displacement agent, to increase the contact area with crude oil, improve the purpose of crude oil desorption efficiency. Among them, potassium sorbate as nanoparticle surface adsorbent can improve the dispersibility of nanoparticle, trehalose lipid is used to improve its amphiphilicity and enhance the emulsification effect. As can be seen, by adding different types of functional surface ligand and nanoparticle, the application of nanoparticle can be improved.

[0006] At present, the application of photothermal conversion type nano materials in oil production engineering is relatively less, and the preparation process is relatively complex, without fully considering the adaptability to formation environment and fluid. The research on the preparation of photothermal conversion type nano materials by biological method needs to be developed. SUMMARY

[0007] In view of the defects of the prior art, the present application provides a photothermal conversion type nano material, a preparation method thereof and a percolation chart construction method.

[0008] Specifically, the present application is realized by the following technical solutions:

[0009] A photothermal conversion type nano material comprises:

[0010] A silver selenide nanocrystal core;

[0011] A composite layer coated on the surface of the silver selenide nanocrystal core; wherein the composite layer is selected from

[0012] (i) a composite layer of a first chemical ligand and a second chemical ligand; or

[0013] (ii) a composite layer of a microorganism or extract and a biosurfactant.

[0014] The photothermal conversion type nano material described above, the first chemical ligand includes at least one of glutathione, human serum albumin, bovine serum albumin, polydopamine.

[0015] The photothermal conversion type nano material described above, the second chemical ligand includes at least one of dodecyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, hexadecyltrimethylammonium bromide, polyester, mercaptocaproic acid.

[0016] The photothermal conversion type nano material described above, the microorganism includes one or more of pseudomonas and shewanella.

[0017] The photothermal conversion type nano material described above, the extract is a plant extract.

[0018] The above-mentioned photothermal conversion type nanomaterial, the biosurfactant includes one or more of saponin, mannose erythritol lipid, Alasan, surfactin, fenjixu.

[0019] A chemical preparation method of a photothermal conversion type nanomaterial, comprising:

[0020] S11 dissolving silver precursor in deionized water, then adding first chemical ligand and warming to 30-90℃, to obtain first solution;

[0021] S12 dissolving selenium precursor in deionized water, then adding reducing agent and second chemical ligand, to obtain second solution;

[0022] S13 dropwise adding the second solution to the first solution, synchronously adjusting pH;

[0023] S14 when the solution gradually turns into red-brown, stopping the reaction and cooling.

[0024] The above-mentioned chemical preparation method of a photothermal conversion type nanomaterial, the silver precursor includes one of silver nitrate, organic sulfonic acid silver.

[0025] The above-mentioned chemical preparation method of a photothermal conversion type nanomaterial, the first chemical ligand includes at least one of glutathione, human serum albumin, bovine serum albumin, polydopamine.

[0026] The above-mentioned chemical preparation method of a photothermal conversion type nanomaterial, in step S11, the temperature of the first solution after warming is 30-90℃.

[0027] The above-mentioned chemical preparation method of a photothermal conversion type nanomaterial, the selenium precursor includes one of selenium powder, sodium selenate, organic selenium compound.

[0028] The above-mentioned chemical preparation method of a photothermal conversion type nanomaterial, the reducing agent is one of sodium borohydride, ascorbic acid, sodium citrate, vitamin.

[0029] The above-mentioned chemical preparation method of a photothermal conversion type nanomaterial, the second chemical ligand includes at least one of dodecyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, hexadecyltrimethylammonium bromide, polyester, mercaptocaproic acid.

[0030] The above-mentioned chemical preparation method of a photothermal conversion type nanomaterial, in step S13, the pH is 4-6.

[0031] The chemical preparation method of the above-mentioned photothermal conversion type nanomaterial, the weight ratio of the silver precursor, the selenium precursor, the first chemical ligand, the second chemical ligand and the reducing agent is (254-66500):(60-550):(750-160000):(280-160000):(15-350).

[0032] The chemical preparation method of the above-mentioned photothermal conversion type nanomaterial, the reaction time in step S14 is 10-480 min.

[0033] A chemical biological preparation method of a photothermal conversion type nanomaterial, comprising:

[0034] S21 mixing the silver precursor and the selenium precursor in deionized water with pH 6-9 to obtain a precursor mixed solution;

[0035] S22 adding microorganisms or plant extracts to the precursor mixed solution and incubating;

[0036] S23 separating and purifying the product after the reaction ends, and adding a biological surfactant to the product for compounding modification.

[0037] The chemical biological preparation method of the above-mentioned photothermal conversion type nanomaterial, the silver precursor comprises one of silver nitrate and organic sulfonic acid silver; the selenium precursor comprises one of selenium powder, sodium selenate and organic selenium compound.

[0038] The chemical biological preparation method of the above-mentioned photothermal conversion type nanomaterial, the microorganisms comprise one or more of Pseudomonas and Shewanella.

[0039] The chemical biological preparation method of the above-mentioned photothermal conversion type nanomaterial, the microorganisms are pre-cultured in a culture medium to an OD 580 of the culture solution of about 0.4-0.7; based on 10-30 mL of the precursor mixed solution, the addition amount of the microorganism culture solution is 15-60 mL, and the addition amount of the plant extract is 1-5 g of solid or 3-6 mL of liquid.

[0040] The chemical biological preparation method of the above-mentioned photothermal conversion type nanomaterial, the incubation temperature is 30-40℃, and the shaking table oscillation is 50-200 rpm.

[0041] The chemical biological preparation method of the above-mentioned photothermal conversion type nanomaterial, the weight ratio of the silver precursor, the selenium precursor and the biological surfactant is (240-66500):(60-510):(1500-11800).

[0042] A photothermal conversion type nanomaterial is prepared by the chemical preparation method of the photothermal conversion type nanomaterial or the chemical biological preparation method of the photothermal conversion type nanomaterial.

[0043] A seepage chart construction method is a construction method of a thermal imaging driven nanofluid seepage chart, comprising:

[0044] S31 injecting the photothermal conversion type nanomaterial into an oil-bearing core after displacement of formation water;

[0045] S32 after injecting 0.3-5 PV of the nanomaterial, irradiating the core with a laser matching the absorbance of the nanomaterial for 10-30 minutes;

[0046] S33 recording the temperature field distribution of the core pore by a thermal imager in real time, and constructing a seepage chart by correlating the nanomaterial migration path.

[0047] The seepage chart construction method has the laser irradiation power density of 1-10 W / cm 2 , and the irradiation mode is uniform irradiation of the whole core section.

[0048] The technical scheme of the present application has the following beneficial effects:

[0049] (1) The preparation method of the photothermal conversion type nanomaterial has the characteristics of simple and efficient operation, green environmental protection and low cost, including chemical method, microbial fermentation method and plant extract method;

[0050] (2) The preparation method improves the stability, hydrophilic and lipophilic properties and temperature and salt resistance of the nanometer particles through surface modification;

[0051] (3) The photothermal conversion type nanomaterial has the ability of emulsification, viscosity reduction and oil displacement, can be compounded with biological surfactants to form a green oil production agent, and can also use the photothermal response signal to construct an infrared thermal imaging driven pore throat network dynamic characterization model;

[0052] (4) The photothermal conversion type nanomaterial has the ability of tracing and oil displacement, can perform laboratory oil displacement evaluation experiments to establish a nanometer particle distribution model in the core pore throat, and can also be applied to the field to serve as a chemical oil displacement agent to help efficient development of offshore crude oil. BRIEF DESCRIPTION OF DRAWINGS

[0053] Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments with reference made to the accompanying drawings. The drawings are for purposes of illustration only and are not considered as limiting the application.

[0054] Figure 1 A transmission electron microscope image of the photo-thermal conversion type nanomaterial synthesized in Example 1;

[0055] Figure 2 An ultraviolet-visible absorption spectrum of the nanomaterial in Example 1;

[0056] Figure 3 An X-ray diffraction image of the nanomaterial in Example 1;

[0057] Figure 4 An infrared spectrum image of the nanomaterial in Example 1;

[0058] Figure 5 A photograph of the nanomaterial of Example 1 in simulated formation water;

[0059] Figure 6 A transmission electron microscope image of the nanomaterial in Example 2;

[0060] Figure 7 An ultraviolet-visible absorption spectrum of the nanomaterial in Example 2;

[0061] Figure 8 An X-ray diffraction image of the nanomaterial in Example 2;

[0062] Figure 9 A photograph of the nanomaterial of Example 2 in simulated formation water;

[0063] Figure 10 A transmission electron microscope image of the nanomaterial in Example 3;

[0064] Figure 11 A contact angle measurement graph of the nanomaterial;

[0065] Figure 12 A photograph of the nanomaterial of Example 3 in simulated formation water;

[0066] Figure 13 A thermography image of the migration process of the nanomaterial in Example 4 in a core pore. DETAILED DESCRIPTION

[0067] In order to fully understand the purpose, features and effects of the present application, the present application will be described in detail through the following specific embodiments. The process method of the present application uses conventional methods or devices in the art except for the following content. The following terms have the meanings commonly understood by those skilled in the art unless otherwise specified.

[0068] When a numerical range is disclosed herein, the range is to be construed as continuous along the entire range and to include each and every value within the range. Further, these ranges can be combined when providing a range description for a feature or characteristic. In other words, unless otherwise indicated, all ranges disclosed herein are to be understood as being inclusive of the ends and of each and every value within the range.

[0069] The inventive concept and principle of the present application are that, on the one hand, nanomaterials have irreplaceable advantages in improving oil recovery due to their unique surface effects, and the modification of the material body can also be achieved by simple surface treatment, which is simple and convenient, and the functions of the material in emulsification, viscosity reduction and residual oil displacement are expandable; on the other hand, based on the unique photo-thermal coupling effect of nanoparticles, in addition to its effect in oil displacement, an infrared thermal imaging driven pore throat network dynamic characterization model can be established, and through the iteration optimization of the photo-thermal response signal and the micro-flow state simulation, the adaptive migration path planning of the nanofluid in the porous medium is guided.

[0070] Specifically, the present application provides a photo-thermal conversion type nanomaterial, comprising:

[0071] a silver selenide nanocrystal core;

[0072] a composite layer coated on the surface of the silver selenide nanocrystal core; wherein the composite layer is selected from

[0073] (i) a composite layer of a first chemical ligand and a second chemical ligand; or

[0074] (ii) a composite layer of a microorganism or extract and a biosurfactant.

[0075] The photo-thermal conversion type nanomaterial of the present application has the ability of emulsification, viscosity reduction and oil displacement, can be compounded with a biological surfactant to form a green oil recovery agent, and can also use its photo-thermal response signal to construct an infrared thermal imaging driven pore throat network dynamic characterization model.

[0076] The photo-thermal conversion type nanomaterial can be prepared by a chemical method, a microbial fermentation method or a plant extract method.

[0077] Specifically, the chemical preparation method of the photo-thermal conversion type nanomaterial comprises:

[0078] S11 dissolving a silver precursor in deionized water, then adding a first chemical ligand and heating to 30-90℃ to obtain a first solution;

[0079] S12 dissolving a selenium precursor in deionized water, then adding a reducing agent and a second chemical ligand to obtain a second solution;

[0080] S13 adding the second solution into the first solution, and synchronously adjusting pH to 4-6;

[0081] S14 reacting for 10-480 min, stopping the reaction and cooling when the solution gradually turns into red-brown.

[0082] In the chemical method for preparing the light-heat conversion type nanomaterial, the silver precursor and the selenium precursor exist in the form of ions in water, and are combined with ligands to form intermediate states respectively, the two kinds of ions are combined at a suitable nucleation and growth temperature to form nanocrystal nuclei with small size, then a large number of intermediate state ions contact the surface of the crystal nucleus to start growing on the surface of the crystal nucleus, and finally the nanomaterial with a suitable size is formed.

[0083] In some preferred embodiments, the silver precursor comprises one of silver nitrate, organic sulfonic acid silver.

[0084] In some preferred embodiments, the selenium precursor comprises one of selenium powder, sodium selenate, organic selenium compounds (such as selenocystine, etc.).

[0085] In the present application, the first chemical ligand and the second chemical ligand have similar effects, the first effect is to stabilize the nanomaterial, so that it is stably dispersed in the solution and does not fail due to aggregation and aging; the second effect is to functionally modify the nanomaterial as a surfactant, to endow the material with the effects of wetting reversal, emulsification viscosity reduction and oil displacement. The two kinds of ligands are added with different precursors, on the one hand based on the solubility of the ligand in deionized water, and on the other hand the ligand will combine with the precursor during the dissolution process in water, which can accelerate the reaction rate of the nanomaterial synthesis reaction, so the two kinds of chemical ligands are dissolved with the two kinds of precursors respectively, which is also designed according to the affinity between the ligand and the precursor.

[0086] In some preferred embodiments, the first chemical ligand comprises at least one of glutathione, human serum albumin, bovine serum albumin, polydopamine.

[0087] In some preferred embodiments, the second chemical ligand comprises at least one of dodecyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, hexadecyltrimethylammonium bromide, polyester, mercaptocaproic acid.

[0088] In the present application, the reducing agent is used to reduce the selenium precursor, so that it fully combines with the silver precursor to form the nanomaterial.

[0089] In some preferred embodiments, the reducing agent is one of sodium borohydride, ascorbic acid, sodium citrate, vitamins.

[0090] In some preferred embodiments, the weight ratio of the silver precursor, the selenium precursor, the first chemical ligand, the second chemical ligand and the reducing agent is (254-66500):(60-550):(750-160000):(280-160000):(15-350).

[0091] Due to the different types of different components, which can range from small molecule compounds to high molecular polymers, in order to ensure the appropriate concentration in the reaction, the mass span is usually large.

[0092] In practice, if the ratio of the two precursors is not uniform, it can lead to the formation of mixed-phase crystals, which can cause poor size uniformity of the material, poor photothermal effect, poor stability, easy aggregation or failure to dissolve normally, and even failure to form nanocrystals that meet the requirements. If the amount of reducing agent added is insufficient, the intermediate state of selenium involved in the reaction may be insufficient, the activity of the selenium precursor may be reduced, and the nanomaterial may not be formed; if the amount added is too much, the silver precursor may be reduced, and the nanomaterial may not be formed. The combination of the two chemical ligands on the surface of the nanomaterial is a competitive relationship, and an uneven ratio can disrupt the competitive balance, causing more of one ligand to be combined on the surface of the nanomaterial. Since the two ligands are mostly long-chain organic ligands or polymers, there is a certain steric hindrance, which can affect the combination of ligands on adjacent binding sites, causing poor material stability, serious Auger recombination, and decreased photothermal conversion performance.

[0093] In another aspect, the photo-thermal conversion type nanomaterial chemical biological preparation method of the present application comprises:

[0094] S21 mixing the silver precursor and the selenium precursor in deionized water with a pH of 6-9 to obtain a precursor mixed solution;

[0095] S22 adding microorganisms or plant extracts to the precursor mixed solution and incubating at 30-40℃; for microorganisms, the incubation time is 12-72h; for plant extracts, the incubation time is 60-480min;

[0096] S23 separating and purifying the product after the reaction is completed, and adding a biological surfactant to the product for compounding modification.

[0097] The metabolic action of the microorganism can reduce the selenium precursor to an intermediate state suitable for reaction, meet the intermediate state formed by the silver precursor, combine at a suitable nucleation and growth temperature to form a nanocrystal nucleus of small size, and then a large number of intermediate state ions contact the surface of the crystal nucleus to start growing on the surface of the crystal nucleus, and finally form a nanomaterial of suitable size. The plant extract contains a certain amount of biological enzymes, which have reducing properties. After reducing the selenium precursor to an intermediate state suitable for reaction, the biological surfactant can also combine with it in the form of a biological surfactant existing on the surface of the nanomaterial to play a stabilizing and oil displacement role.

[0098] In some preferred embodiments, the silver precursor includes one of silver nitrate and organic silver sulfonate; and the selenium precursor includes one of selenium powder, sodium selenate, and an organic selenium compound (such as selenocystine, etc.).

[0099] The microbial metabolites and plant extracts contain certain biological enzymes and biological surfactants (such as rhamnolipid surfactants, tea saponin, etc.). These substances can be adsorbed on the surface of the nanomaterial to enhance the adaptation of the material to the formation fluid and the like, while reducing the water-oil interfacial tension and imparting certain oil displacement effect to the material

[0100] In some preferred embodiments, the microorganism includes one or more of Pseudomonas and Shewanella; and the plant extract is an extract of aloe vera, green tea, or the like.

[0101] In some preferred embodiments, the microorganism is pre-cultured in a culture medium until the OD 580 of the culture solution is about 0.4-0.7. Based on 10-30 mL of the precursor mixed solution, the amount of the microorganism (including the culture solution) added is 15-60 mL; and the amount of the plant extract added is 1-5 g of solid or 3-6 mL of liquid.

[0102] The biological surfactant can make the nanomaterial stably dispersed, improve the wettability of the material surface, make the material play an oil displacement effect, and enhance the adaptability to the formation environment

[0103] In some preferred embodiments, the biological surfactant includes one or more of saponin, mannosylerythritol lipid, Alasan, surfactin, and fenxijin.

[0104] In some preferred embodiments, the weight ratio of the silver precursor, the selenium precursor, and the biological surfactant is (240-66500):(60-510):(1500-11800).

[0105] If the ratio of the two precursors is not uniform, mixed-phase crystals will be formed, which can result in poor size uniformity of the material, poor photothermal effect, poor stability, easy aggregation or failure to dissolve normally, or even failure to form nanocrystals that meet the requirements

[0106] In another aspect, the application also provides a method for constructing a nanofluid seepage chart driven by thermal imaging, comprising:

[0107] S31 injecting the photothermal conversion nanomaterial of any one of claims 1-6 or 22 into the oil-bearing core after displacement by formation water;

[0108] S32 after injecting 0.3-5 PV of the nanomaterial, irradiating the core with a laser matching the absorbance of the nanomaterial for 10-30 minutes;

[0109] S33 recording the temperature field distribution of the core pores in real time by a thermal imager and correlating the nanomaterial migration path to construct a seepage chart.

[0110] In some preferred embodiments, the irradiation power density of the laser is 1-10 W / cm 2 , and the irradiation mode is uniform irradiation of the whole core section, so that the nanomaterial in the pores absorbs the light energy and converts it into heat to raise its temperature. On the one hand, a seepage chart based on thermal imaging can be constructed according to the flow of the nanomaterial, and on the other hand, heat transfer occurs between the nanomaterial with higher temperature and the remaining oil in the pores, which can reduce the viscosity of the crude oil and improve the oil displacement efficiency of the material

[0111] In some preferred embodiments, the spatial resolution of the temperature field distribution is and the temperature detection accuracy is limited by the instrument accuracy, which is not specifically limited in the application.

[0112] In the application, the core temperature distribution image shows the aggregation position of the nanomaterial, and the aggregation degree of the material in the pore structure with higher temperature is higher. The two-dimensional image displayed by thermal imaging under different displacement volumes can provide information about the local temperature of the core and the specific position of the core, and using this information, the static distribution of the nanofluid in the pores and the dynamic migration law can be constructed to assist in the characterization of pore throat characteristics and the description of fluid seepage process.

[0113] Examples

[0114] The application will be further described by way of examples, but the application is not limited to the examples. The experimental methods in the following examples are not specified, and the conventional methods and conditions are used. The raw materials used in the following examples are commercially available.

[0115] Example 1

[0116] A chemical synthesis method of a photothermal conversion type nanomaterial, the steps are as follows:

[0117] (1) Dissolve 9 g of silver lignin sulfonate as a preferred silver precursor in 50 mL of deionized water, and make the solution fully dissolved to a clear state, add 20 g of polydopamine ligand, and gradually warm up to 60-75°C;

[0118] (2) Dissolve 0.2 g of selenocysteine as a preferred selenium precursor in 20 mL of deionized water, add 25 mg of sodium citrate and 0.85 g of CTAB, and preheat to dissolve to 50°C, slowly add the silver precursor solution in step (1) after the solution is clear, and adjust the pH of the solution to 4-6 while adding;

[0119] (3) Control the drop speed, and gradually warm up to 80-90°C, the solution gradually turns red-brown, stop the reaction and cool to room temperature.

[0120] In this embodiment, the transmission electron microscope image of the nanomaterial is as shown in Figure 1 , the ultraviolet-visible absorption spectrum curve of the nanomaterial stock solution is as shown in Figure 2 , the X-ray diffraction result of the material is as shown in Figure 3 , and the infrared spectrum image is as shown in Figure 4 .

[0121] These tests can prove the successful synthesis of the nanomaterial, which has a particle size of about 10 nm, a good cubic phase crystal structure, a surface coated with biological surfactants and organic ligands rich in carboxyl, hydroxyl and mercapto groups, and good stability.

[0122] After diluting the nanomaterial of Example 1 by 10 times, take 5 mL, add 5 mL of 25000 mg / L salinity simulated formation water, and stand at 70°C for 20 min. It is observed that the system can remain clear (see Figure 5 ), which proves that it has good stability and temperature and salt resistance.

[0123] Example 2

[0124] A chemical synthesis method of a photothermal conversion type nanomaterial, the steps are as follows:

[0125] (1) Dissolve 0.42 g of silver nitrate and 0.20 g of sodium selenate in 25 mL of deionized water and mix uniformly to obtain a precursor mixed solution;

[0126] (2) Add 2.75 g of freshly extracted green tea extract, adjust the pH to 6-7, control the reaction temperature to 45-70°C, stir in the dark, and incubate for 20-48 h;

[0127] (3) centrifugation, rinsing the product with a small amount of ethanol, and adding 5.85 g of the biosurfactant finicin for compounding.

[0128] In this embodiment, the transmission electron microscope image of the nanomaterial is shown in Figure 6 ; the ultraviolet-visible absorption spectrum curve of the nanomaterial stock solution is shown in Figure 7 ; and the X-ray diffraction result of the material is shown in Figure 8 .

[0129] The nanomaterial synthesized by the method set forth in this embodiment is similar to that of Example 1 in appearance, structure and composition, and can be applied to synthesis of stable and uniform nanomaterials, with a particle size of about 11.3 nm and good chemical stability and colloidal stability.

[0130] After the nanomaterial of Example 2 is diluted 10 times, 5 mL thereof is taken and added into 5 mL of simulated formation water with a salinity of 25000 mg / L, and is left to stand at 70℃ for 20 min. It is observed that the system can remain clear (see Figure 9 ), proving that it has good stability and temperature resistance and salt tolerance.

[0131] Example 3

[0132] A chemical-biosynthesis method of a photothermal conversion type nanomaterial, comprising the following steps:

[0133] (1) dissolving 0.51 g of silver nitrate and 0.18 g of sodium selenate in 15 mL of deionized water to obtain a precursor mixed solution;

[0134] (2) adding the precursor mixed solution into 30 mL of a culture medium (the OD 580 of the culture solution is 0.586) of Shewanella oneidensis, so that the bacteria perform anaerobic respiration, the pH is adjusted to 6.8-7.5, the reaction temperature is controlled at 30-40℃, and the bacteria are cultured for 48-72 h under shaking bed oscillation;

[0135] (3) after the reaction is completed, the culture solution is ultrasonically treated to destroy the bacterial cells;

[0136] (4) centrifugal separation, and adding 2.8 g of the biosurfactant saponin for compounding.

[0137] In this embodiment, the transmission electron microscope image of the nanomaterial is shown in Figure 10 .

[0138] The concentration of the material was calibrated by the absorbance value of the nanomaterial at 620nm, and the surface tension of the nanomaterial was measured by diluting it 5 times with deionized water using the contact angle method. The contact angle of the nanomaterial at this dilution ratio was obtained, as shown in Figure 5. Figure 11 shown.

[0139] After diluting the nanomaterial of Example 2 by 10 times, 5 mL was taken and 5 mL of simulated formation water with a salinity of 25000 mg / L was added thereto. The mixture was allowed to stand at 70°C for 20 min. It was observed that the system could remain clear (see Figure 12 ), proving its good stability and temperature and salt resistance.

[0140] Example 4

[0141] A method for constructing a nanofluid seepage map driven by thermal imaging, comprising the following steps:

[0142] The preferred offshore oilfield core was dried for 48 hours, crude oil was injected into the core to saturate the core, and formation water was used to displace the core until the water content at the outlet was above 98%. At room temperature, 5 PV of the photothermal conversion nanomaterial prepared in Example 1 was injected into the oil-bearing core after the formation water was displaced. For every 1 PV of nanomaterial displaced, a wavelength of 632 nm and a power density of 4 W·cm were used. -2 The laser is used to evenly irradiate the oil-bearing core for 10-30 minutes, and a thermal imager is used to observe the temperature changes in the core pores during the displacement of the nanomaterial. Figure 13 shown.

[0143] The core temperature distribution image reveals the locations where the nanomaterials are concentrated, with higher concentrations occurring in pore structures with higher temperatures. Temperature distributions vary across the core profile and across contiguous areas at different displacement volumes. The photothermal nanomaterials in the pores migrate as the displacement progresses, heating up due to the laser energy. Comparing temperature changes at various locations in the core during the displacement process reveals the migration pathways of the nanomaterials within the core pores. This is crucial for revealing the distribution of residual oil in the core pores, visualizing the nanofluid flooding process, and validating pore structure models.

[0144] The present invention has been disclosed above with reference to preferred embodiments. However, those skilled in the art will appreciate that these embodiments are intended only to illustrate the present invention and are not to be construed as limiting the scope of the present invention. It should be noted that any equivalent variations and substitutions to these embodiments are to be considered encompassed within the scope of the claims of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope defined in the claims.

Claims

1. A photothermal conversion nanomaterial, characterized in that: include: Silver selenide nanocrystal core; A composite layer coated on the surface of the silver selenide nanocrystal core; wherein the composite layer is selected from (i) a composite layer of a first chemical ligand and a second chemical ligand; or (ii) A composite layer of microorganisms or extracts and biosurfactants.

2. The photothermal conversion nanomaterial according to claim 1, characterized in that: The first chemical ligand includes at least one of glutathione, human serum albumin, bovine serum albumin, and polydopamine.

3. The photothermal conversion nanomaterial according to claim 1, characterized in that: The second chemical ligand includes at least one of dodecyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, hexadecyltrimethylammonium bromide, polyester, and mercaptohexanoic acid.

4. The photothermal conversion nanomaterial according to claim 1, characterized in that: The microorganisms include one or more of Pseudomonas and Shewanella.

5. The photothermal conversion nanomaterial according to claim 1, characterized in that: The extract is a plant extract.

6. The photothermal conversion nanomaterial according to claim 1, characterized in that: The biosurfactant comprises one or more of saponin, mannoerythritol ester, Alasan, surfactin and fennel.

7. A chemical preparation method of photothermal conversion nanomaterials, characterized in that: include: S11 dissolving a silver precursor in deionized water, then adding a first chemical ligand and heating to 30-90° C. to obtain a first solution; S12 dissolving a selenium precursor in deionized water, and then adding a reducing agent and a second chemical ligand to obtain a second solution; S13: adding the second solution dropwise to the first solution and adjusting the pH simultaneously; S14 When the solution gradually turns reddish brown, stop the reaction and cool.

8. The preparation method according to claim 7, characterized in that The silver precursor includes one of silver nitrate and organic silver sulfonate.

9. The preparation method according to claim 7, characterized in that The first chemical ligand includes at least one of glutathione, human serum albumin, bovine serum albumin, and polydopamine.

10. The preparation method according to claim 7, characterized in that In step S11, the temperature of the first solution after heating is 30-90°C.

11. The preparation method according to claim 7, characterized in that The selenium precursor includes one of selenium powder, sodium selenate, and an organic selenium compound.

12. The preparation method according to claim 7, characterized in that The reducing agent is one of sodium borohydride, ascorbic acid, sodium citrate and vitamins.

13. The preparation method according to claim 7, characterized in that The second chemical ligand includes at least one of dodecyltrimethylammonium bromide, tetradecyltrimethylammonium bromide, hexadecyltrimethylammonium bromide, polyester, and mercaptohexanoic acid.

14. The preparation method according to claim 7, characterized in that In step S13, the pH is 4-6.

15. The preparation method according to claim 7, characterized in that The weight ratio of the silver precursor, the selenium precursor, the first chemical ligand, the second chemical ligand and the reducing agent is (254-66500):(60-550):(750-160000):(280-160000):(15-350).

16. The preparation method according to claim 7, characterized in that In step S14, the reaction time is 10-480 min.

17. A chemical-biological preparation method of photothermal conversion nanomaterials, characterized in that: include: S21: mixing a silver precursor and a selenium precursor in deionized water at a pH of 6-9 to obtain a precursor mixed solution; S22 adding a microorganism or plant extract to the precursor mixed solution and incubating; After the S23 reaction is completed, the product is separated and purified, and a biosurfactant is added to the product for compounding and modification.

18. The preparation method according to claim 17, characterized in that: The silver precursor includes one of silver nitrate and organic silver sulfonate; the selenium precursor includes one of selenium powder, sodium selenate and organic selenium compound.

19. The preparation method according to claim 17, characterized in that The microorganisms include one or more of Pseudomonas and Shewanella.

20. The preparation method according to claim 17, characterized in that The microorganisms are cultured in the culture medium to an OD value of 580 About 0.4-0.7; based on 10-30mL of the precursor mixed solution, the amount of microbial culture solution added is 15-60mL, and the amount of plant extract added is 1-5g solid or 3-6mL liquid.

21. The preparation method according to claim 17, characterized in that The incubation temperature is 30-40° C. and the shaking speed is 50-200 rpm.

22. The preparation method according to claim 17, characterized in that The weight ratio of the silver precursor, the selenium precursor and the biosurfactant is (240-66500):(60-510):(1500-11800).

23. A photothermal conversion nanomaterial, characterized in that: The photothermal conversion nanomaterial is prepared by the chemical preparation method of any one of claims 7 to 16 or the chemical-biological preparation method of any one of claims 17 to 22.

24. A method for constructing a seepage map, characterized in that: The method for constructing a seepage map is a method for constructing a nanofluid seepage map driven by thermal imaging, comprising: S31 injecting the photothermal conversion nanomaterial according to any one of claims 1 to 6 and 23 into the oil-bearing core after formation water displacement; S32 After each injection of 0.3-5 PV of the nanomaterial, irradiate the core with a laser having an absorbance matching that of the nanomaterial for 10-30 minutes; S33 uses a thermal imager to record the temperature field distribution of core pores in real time, and associates it with the migration path of nanomaterials to construct a seepage map.

25. The method for constructing a seepage map according to claim 24, wherein: The irradiation power density of the laser is 1-10W / cm 2 The irradiation method is uniform irradiation of the entire core cross section.

Images