A dual-function thickened oil catalytic viscosity reduction system and viscosity reduction method

Abstract

The application discloses a kind of bifunctional thick oil catalytic viscosity reduction system and viscosity reduction method, bifunctional thick oil catalytic viscosity reduction system is adjusted to be the catalytic-emulsion composite viscosity reduction system of mixed catalyst, oxidizing agent after using surfactant, wherein, catalyst is amphiphilic TM / C-NH2 Nanoparticle, the oxidizing agent is organic peroxide.Catalytic-emulsion composite viscosity reduction system is mixed with thick oil and heated to reservoir environmental temperature reaction after, reaction is completed after finishing to thick oil viscosity reduction.The application is configured into the catalytic-emulsion composite viscosity reduction system of water-in-oil by organic peroxide oxidizing agent compound emulsifier, in reservoir environment (50~180 DEG C), using the catalytic oxidation performance of catalyst viscosity reduction system and catalyst and oxidized oil oxygen-containing group adsorption self-assembly function, realize thick oil macromolecule depolymerization and wettability reverse, further improve the viscosity reduction efficiency.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of crude oil viscosity reduction, and relates to a catalytic viscosity reduction technology for crude oil, in particular to a dual-function heavy oil catalytic viscosity reduction system and a viscosity reduction method. BACKGROUND

[0002] Heavy oil is a kind of relatively viscous petroleum, which generally refers to crude oil with high content of asphaltene and resin, and large density and viscosity. Compared with crude oil, heavy oil has both common characteristics of petroleum and its own characteristics, and is a complex multi-component complex hydrocarbon mixture composed of alkanes, arenes, resins and asphaltene. Among them, resin and asphaltene are high molecular weight components, and contain metals and non-metals such as sulfur, nitrogen, oxygen and other heteroatoms. Asphaltene is the component with the most complex structure, the largest relative molecular weight and the largest relative density in crude oil. High viscosity and high density are the main characteristics of heavy oil, which are also the main indicators that distinguish heavy oil from ordinary light crude oil. The viscosity of heavy oil is sensitive to temperature, and decreases sharply with the increase of temperature. Both deep heavy oil and shallow heavy oil have the common problem of high viscosity and poor flowability. Therefore, it is the key to solve the problem to clarify the mechanism of viscosity of heavy oil. According to the analysis, the two components of resin and asphaltene contribute most to the viscosity. Resin contains condensed cyclic system composed of heavy oil, alicyclic and side chain, and contains nitrogen, sulfur, oxygen and other heteroatoms. Asphaltene is a complex mixture of various condensed aromatic hydrocarbons, naphthenes and paraffins, as well as metals and non-metals, with high content of heteroatoms and low hydrogen-carbon atomic ratio. Among them, asphaltene is the key factor of viscosity of heavy oil. The structure of asphaltene is related to the content of metal and heteroatom, the size of intermolecular force and the relative molecular mass. Through the previous exploration, it can be found that the catalytic oxidation technology can be used to reduce the content of heteroatom and weaken the intermolecular force by catalytic reaction, which is beneficial to reduce the viscosity of heavy oil.

[0003] The principle of viscosity reduction by catalytic oxidation method is that the aromatic heterocyclic macromolecules in resin and asphaltene molecules in heavy oil are oxidized under the action of catalyst, the side chain containing heteroatoms is broken, and alcohol group, carbonyl group and carboxyl group organic molecules and organic molecules containing sulfonic acid group are formed. These molecules generally have certain dispersion performance, and can improve the dispersion of each molecule in heavy oil under the premise of not being affected by hydrogen bond. However, the defect is that the oxygen-containing groups are easily adsorbed by heavy oil macromolecules again, resulting in increase of viscosity, so the viscosity reduction effect is difficult to continue to increase after reaching a certain degree.

[0004] Emulsification viscosity reduction of heavy oil is a method of converting heavy oil into a small molecule suspended dispersion system to reduce viscosity. Emulsification viscosity reduction technology can effectively improve the flowability of heavy oil, thereby improving the utilization rate of heavy oil. The principle of emulsification viscosity reduction technology is to reduce viscosity through the emulsion formed after emulsification of heavy oil. The technology for forming heavy oil emulsion includes water-soluble emulsification viscosity reduction technology, oil-soluble chemical viscosity reducer technology and surfactant viscosity reduction technology. Although emulsification viscosity reduction technology is mature, there are certain limitations in actual application. For water-soluble emulsification viscosity reduction technology, in theory, heavy oil is dispersed in active water in the form of small oil droplets to form an O / W type emulsion, so that the friction between heavy oil molecules is converted into water friction, and the viscosity is suddenly reduced. However, in practice, heavy oil cannot completely form ideal emulsion, and crude oil is dispersed in active water in the form of large particles to form a water-in-oil type coarse dispersion system.

[0005] For oil-soluble chemical viscosity reduction technology, it is difficult to meet the actual viscosity requirement for heavy oil with very large viscosity base, and the cost is high due to high price and large amount of viscosity reducer, which has certain use limitation.

[0006] As known from the above, both catalytic viscosity reduction and emulsification viscosity reduction have their own limitations, and the two belong to completely different viscosity reduction mechanisms. The two cannot be used together in the prior art, and if a suitable catalytic viscosity reducer is developed for use together with emulsion viscosity reduction, a new viscosity reduction idea will be opened up. SUMMARY

[0007] The purpose of the present application is to develop a dual-function heavy oil catalytic viscosity reduction system to solve the above technical problems. The HLB value of a catalyst and an oxidant is adjusted by a surfactant to form a heavy oil catalytic viscosity reduction system, wherein the catalyst is an amphiphilic TM / C-NH2 nanoparticle, and the oxidant is an organic peroxide. The present application combines catalytic oxidation technology with emulsification viscosity reduction technology. First, the principle of catalytic oxidation viscosity reduction is used to make the aromatic heterocyclic macromolecules in the resin and asphaltene molecules in heavy oil undergo oxidation reaction under the action of the nano-material catalyst, break the side chains containing heteroatoms, and form alcohol groups, carbonyl groups and carboxyl groups, and organic molecules containing sulfonic acid groups. Then, the amino groups contained in the nano-catalyst and the carboxyl groups in the oxygen-containing groups are adsorbed on the surface of the nano-material by electrostatic self-assembly, so as to change the polarity and interfacial activity of the heavy oil macromolecular depolymerization and wettability reversal, and achieve the purpose of heavy oil viscosity reduction.

[0008] In order to solve the above technical problems, the technical scheme adopted by the present application is as follows:

[0009] In one aspect, the application provides a dual-function thick oil catalytic viscosity reduction system, which is a catalytic-emulsion composite viscosity reduction system with an HLB value of 7-14 after mixing a catalyst and an oxidant with a surfactant for adjustment, wherein the catalyst is an amphiphilic TM / C-NH2 nanoparticle, and the oxidant is an organic peroxide.

[0010] The catalyst contained in the application is a 0-valence transition metal particle supported on a carbon nanosphere particle, and the transition metal is an electrophilic group with an empty orbital and an electronegativity >1.5. The carbon nanosphere particle is grafted with -NH2 on the surface through amino functionalization. The introduction of the electrophilic group -NH2 during the synthesis process increases the electronegativity of the surrounding carbon atoms and improves the attraction to the heteroatom containing a lone pair of electrons in the heavy oil macromolecule. Therefore, the catalytic viscosity reduction system has dual functions of catalytic function and adsorption and dispersion of oxidized heavy components, which not only helps to improve the ability to activate the oxidant before the catalytic reaction, but also enables the self-assembly of the oxidized heavy oil components containing oxygen groups after the catalytic reaction, thereby realizing the depolymerization of heavy oil macromolecules and the reverse wettability.

[0011] The catalyst is dispersed at the oil-water interface of the emulsion, and the oxidant is in the oil phase of the emulsion. A large amount of water exists in the emulsion, which aims to utilize the cooling characteristics of water, i.e., water has a high specific heat capacity (4.2kJ·kg -1 ·K -1 ) and a small change with temperature. One is to prevent the release of active oxygen due to the thermal decomposition of the oxidant, and the other is to reduce the frictional resistance of the system in the wellbore to avoid the residual of the oxidant on the wellbore wall. Until the emulsion breaks in the temperature-stable 140℃ environment of the oil reservoir, the catalyst contacts the oxidant and forms a peroxide complex, which then attacks the heavy oil polycyclic aromatic hydrocarbon side chain and the heteroatom-containing carbon side chain to occur oxidation reaction, forming alcohol, ketone and carboxylic acid, and realizing the oxidation of heavy oil. The formed oxidized groups can combine with the amino groups of the catalyst to promote the reverse wettability of the heavy oil and realize the emulsification of the heavy oil.

[0012] The viscosity reduction principle of the application includes a catalytic oxidation process and an adsorption and dispersion process, and has dual functions of catalytic function and adsorption and dispersion of oxidized heavy components. The catalytic heavy oil is oxidized oil, and can self-assemble with the oxidized oil to realize the depolymerization of heavy oil macromolecules and the reverse wettability.

[0013] Catalytic oxidation process: the oxidant in the catalytic viscosity reduction system is complexed with the transition metal empty orbital and carbon carrier in the catalyst to form a peroxide complex, which attacks the heteroatom side chain of the polycyclic aromatic hydrocarbon in the heavy oil, breaks the C-S bond, encapsulates the oxygen-containing group (-OH), and performs deep oxidation to make the oxygen-containing group mainly carboxyl (-COOH), thereby obtaining heavy oil oxidized oil. This is the catalytic oxidation process.

[0014] Adsorption dispersion process: the -NH2 groups of the TM / C-NH2 nanoparticles can self-assemble with oxygen-containing groups (-COOH) in the oxidized heavy oil, promote the interaction between the nanoparticles and the colloid asphalt macromolecules in the heavy oil, make the macromolecules adsorbed and dispersed on the surface of the nanoparticles, thereby making the polarity of the oxidized colloid asphalt macromolecules reversed and realizing the high dispersion of the heavy oil macromolecules, which is the adsorption dispersion process.

[0015] Further, the amphiphilic TM / C-NH2 nanoparticles are carbon nanospheres loaded with 0-valence transition metals and amino groups.

[0016] The application also provides a preparation method of the TM / C-NH2 nanoparticles, which specifically comprises the following steps:

[0017] Step S1, synthesizing carbon nanospheres;

[0018] Step S2, loading 0-valence transition metals:

[0019] Step S3, grafting -NH2 on the surface of the carbon nanospheres through amino functionalization to obtain TM / C-NH2 nanoparticles.

[0020] Further, in step S1, the carbon nanospheres are synthesized in the following manner:

[0021] Glucose is dissolved in deionized water to obtain a glucose aqueous solution, and the glucose aqueous solution is transferred into a hydrothermal reaction kettle to react at 150-180℃ for 2-5h, and then cooled to room temperature; the solid product is separated by suction filtration, washed and dried to obtain carbon nanospheres.

[0022] Further, in step S1, the concentration of the glucose aqueous solution is 0.2-0.9mol / L.

[0023] Further, in step S1, the solid product is washed with ethanol and deionized water for 2-5 times, respectively.

[0024] Further, in step S1, the obtained solid product is dried in a vacuum drying oven at 55-65℃ overnight to obtain carbon nanospheres.

[0025] Further, in step S2, the 0-valence transition metals are loaded in the following manner:

[0026] The carbon nanospheres are dispersed into a mixed solvent containing deionized water and ethanol to form a suspension; a high-valence transition metal catalyst is added into the suspension, and after ultrasonic mixing, a reducing agent is added; after vigorous stirring, the transition metal in the high-valence transition metal catalyst is reduced to 0-valence and loaded on the carbon nanospheres; and the mixed solution is centrifuged to collect the filter residue, which is washed to obtain carbon nanospheres loaded with 0-valence transition metals.

[0027] Further, the volume ratio of deionized water and ethanol in the mixed solvent of step S2 is 1:1-1:4.

[0028] Further, in step S2, the high-valence transition metal catalyst is added after ultrasonic stirring for 10-30 min, and the ultrasonic stirring is continued for 8-20 min after the catalyst is added.

[0029] Further, in step S2, the transition metal includes elements of group IIIB, group VB, group VIB, group VIIB and group VIII; the elements of group IIIB include Ti, Zr and Hf; the elements of group VB include V, Nb and Ta; the elements of group VIB include Cr, Mo and W; the elements of group VIIB include Mn, Tc and Re; and the elements of group VIII include Fe, Co, Ni, Ru, Rh, Pd, Os, Ir and Pt.

[0030] Specifically, the high-valence transition metal catalyst is a transition metal acetate, such as C4H6O4•Co•4H2O, Ni(CH3COO)2, Mn(CH3COO)2, Zr(CH3COO)4 and Fe(OH)(CH3COO)2.

[0031] Further, in step S2, the reducing agent is NaBH4 aqueous solution, and the concentration of the NaBH4 aqueous solution is 0.1-0.45 mol / L.

[0032] Further, in step S2, the mixed solution is centrifuged to collect the filter residue, the solid product is washed with ethanol and deionized water for 2-5 times, and then dried in a vacuum drying oven at 55-65°C overnight to obtain the carbon nanosphere particles loaded with 0-valence transition metal.

[0033] Further, in step S3, the method for grafting -NH2 is as follows:

[0034] The carbon nanosphere particles loaded with 0-valence transition metal are dispersed in ammonia water to form a suspension, which is uniformly mixed by ultrasonic mixing and then transferred to a reaction kettle. The reaction kettle is heated to 150-180°C for reaction for 16-30 h, and then naturally cooled to room temperature. The obtained product is centrifuged and washed with deionized water and ethanol to obtain TM / C-NH2 nanoparticles.

[0035] Further, the organic peroxide is any one of hydroperoxide, dialkyl peroxide, diacyl peroxide, peroxyester, peroxide carbonate and ketone peroxide.

[0036] Further, the organic peroxide is benzenecarboperoxoic acid, benzoyl peroxide and hydrogen peroxide.

[0037] Further, in the dual-function thick oil catalytic viscosity reduction system, the mass ratio of the catalyst and the oxidant is 1:1-1:3.

[0038] Further, the surfactant is a composite surfactant composed of a hydrophilic surfactant and an oleophilic surfactant.

[0039] Further, the hydrophilic surfactant and the oleophilic surfactant are both non-ionic surfactants; wherein the hydrophilic non-ionic surfactant includes polyoxyethylene type, polyhydric alcohol type, alkanol amide type, polyether type, amine oxide type surfactants, and specifically can be Span-(sorbitan monolaurate), dodecyl polyoxyethylene ether (AEO-12), silane coupling agent (KH-560), alkyl phenol polyoxyethylene ether (hydrophilic OP series emulsifier), etc.; and the oleophilic non-ionic surfactant includes Tween-(polysorbate), octylphenol polyoxyethylene ether (oleophilic OP series emulsifier), octanol ether.

[0040] On the other hand, the application provides a method for reducing the viscosity of thick oil by using the above-mentioned dual-function thick oil catalytic viscosity reduction system, comprising the following steps:

[0041] After mixing the catalyst and the oxidant, the surfactant is added to obtain a catalytic-emulsion composite viscosity reduction system;

[0042] After mixing the catalytic-emulsion composite viscosity reduction system with the thick oil, heating is performed to the oil reservoir environment (50-180 DEG C) temperature for reaction, and after the reaction is completed, the viscosity reduction of the thick oil is finished.

[0043] Further, the addition amount of the catalytic-emulsion composite viscosity reduction system, calculated based on the catalyst, is 0.01%-1% of the mass of the thick oil.

[0044] Further, the oil reservoir environment is 50-180 DEG C, and the reaction time is 1-48 hours.

[0045] Compared with the prior art, the application has the following effects:

[0046] In the application, the oxidant organic peroxide compound emulsifier is configured into a catalytic-emulsion composite viscosity reduction system of oil-in-water, the carboxyl of the oxidized oil is combined with the amino on the surface of the nano material, and is adsorbed on the surface of the nano material through electrostatic self-assembly, so as to change the polarity and interfacial activity of the heavy component of the oxidation product, realize the depolymerization of the thick oil macromolecule and the wetting reversal, achieve the purpose of thick oil viscosity reduction, and further improve the viscosity reduction efficiency. DETAILED DESCRIPTION

[0047] The embodiments of the application are further described in detail below with reference to the examples. The following examples are used to illustrate the application, but cannot be used to limit the scope of the application. The parts, concentrations and ratios in the following examples are all calculated by mass.

[0048] The organic peroxide and the surfactant are compounded into an oil-in-water emulsion system with the amphiphilic TM / C-NH2 nanoparticles as a catalyst, and the TM / C-NH2 nanoparticle catalyst is dispersed at the oil-water interface of the emulsion to construct a catalytic oxidation system; the thickened oil and a certain amount of the catalytic oxidation system are placed in a high-temperature and high-pressure reaction kettle, and reacted at 140°C for 24h. The obtained catalytically upgraded thickened oil is purified and then analyzed in terms of group components and viscosity.

[0049] Preparation of TM / C-NH2 nanoparticles

[0050] Synthesis of carbon nanospheres; first, 7.2g of glucose is dissolved in 80mL of deionized water, and stirred to fully dissolve to obtain a 0.5mol / L glucose aqueous solution. Then, the 0.5mol / L glucose aqueous solution is transferred to a 100mL hydrothermal reaction kettle, and reacted at 160°C for 3.5h. After cooling to room temperature, the solid product is separated by suction filtration, and washed with ethanol and deionized water three times, respectively. Finally, the obtained solid product is dried in a 60°C vacuum drying oven overnight to obtain carbon nanospheres.

[0051] Loading of 0-valence transition metal; first, 0.5g of carbon nanospheres is dispersed in 100mL of a mixed solvent containing deionized water and ethanol (volume ratio 2:3) to form a suspension. After ultrasonic stirring for 15min, 1.245g of C4H6O4•Co•4H2O is added to the suspension, and ultrasonic stirring is continued for 10min. Next, stirring is performed at room temperature for 2h. Finally, 20mL of a 0.25mol / L NaBH4 aqueous solution is added dropwise to the mixed solution, and the solution is stirred vigorously for 15min. Finally, the obtained mixed solution is centrifuged, washed with ethanol and deionized water three times, and placed in a 60°C vacuum drying oven for drying overnight to obtain 0-valence transition metal-loaded carbon nanospheres (referred to as Co / CNSs).

[0052] Grafting of -NH2 on the surface of carbon nanospheres through amino functionalization; first, the Co / CNSs prepared in the second step are dispersed in 60mL of ammonia water to form a suspension, and ultrasonic stirring is performed for 10min to make the mixture uniform. Then, the high-temperature and high-pressure reaction kettle is placed in a 160°C oven and reacted for 24h. After natural cooling to room temperature, the obtained product is centrifuged, washed with deionized water and ethanol three times, and finally placed in a 60°C vacuum drying oven for drying overnight.

[0053] Preparation of a catalytic-emulsion composite viscosity-reducing system

[0054] Example 1: 3g of TM / C-NH2 nanoparticles were dispersed in 100ml of aqueous benzoyl peroxide solution (concentration of 2%) to obtain an oil-in-water emulsion system, and 0.1% of oleophilic Tween and hydrophilic Span (total concentration of 0.1%, oleophilic: hydrophilic = 0.12:1) were added to adjust the HLB value of the oil-in-water emulsion system to 9.2, to obtain a catalysis-emulsion composite viscosity reduction system.

[0055] Example 2: 3g of TM / C-NH2 nanoparticles were dispersed in 100ml of aqueous benzoyl peroxide solution (concentration of 2%) to obtain an oil-in-water emulsion system, and 0.2% of oleophilic Tween and hydrophilic Span (total concentration of 0.2%, oleophilic: hydrophilic = 0.12:1) were added to adjust the HLB value of the oil-in-water emulsion system to 10, to obtain a catalysis-emulsion composite viscosity reduction system.

[0056] Example 3: 3g of TM / C-NH2 nanoparticles were dispersed in 100ml of aqueous benzoyl peroxide solution (concentration of 2%) to obtain an oil-in-water emulsion system, and 0.3% of oleophilic Tween and hydrophilic Span (total concentration of 0.3%) were added to adjust the HLB value of the oil-in-water emulsion system to 11, to obtain a catalysis-emulsion composite viscosity reduction system.

[0057] Crude oil viscosity reduction experiment:

[0058] Example 4

[0059] The amount of the catalysis-emulsion composite viscosity reduction system was determined with reference to the mass of the thick oil, 0.05% of the catalyst was added, the catalysis-emulsion composite viscosity reduction system prepared in Example 1 was mixed with the crude oil, and then the mixture was reacted in a reaction kettle at 140°C for 24h, and the group components and viscosity of the crude oil after viscosity reduction were tested, as shown in Tables 1 and 2, respectively.

[0060] Example 5

[0061] The amount of the catalysis-emulsion composite viscosity reduction system was determined with reference to the mass of the thick oil, 0.1% of the catalyst was added, the catalysis-emulsion composite viscosity reduction system prepared in Example 1 was mixed with the crude oil, and then the mixture was reacted in a reaction kettle at 140°C for 24h, and the group components and viscosity of the crude oil after viscosity reduction were tested, as shown in Tables 1 and 2, respectively.

[0062] Example 6

[0063] The amount of the catalysis-emulsion composite viscosity reduction system was determined with reference to the mass of the thick oil, 0.2% of the catalyst was added, the catalysis-emulsion composite viscosity reduction system prepared in Example 1 was mixed with the crude oil, and then the mixture was reacted in a reaction kettle at 140°C for 24h, and the group components and viscosity of the crude oil after viscosity reduction were tested, as shown in Tables 1 and 2, respectively.

[0064] Comparative Example 1

[0065] The same amount of organic peroxide as in Example 4 was mixed with surfactant (no catalyst was added), configured into an emulsion system, mixed with crude oil, and then reacted in a reaction kettle at 140°C for 24h. The group components and viscosity of the crude oil after viscosity reduction were tested, as shown in Table 1 and Table 2, respectively.

[0066] Comparative Example 2

[0067] The same amount of catalyst and organic peroxide as in Example 4 (no surfactant was added) was configured into a catalytic oxidation system, mixed with crude oil, and then reacted in a reaction kettle at 140°C for 24h. The group components and viscosity of the crude oil after viscosity reduction were tested, as shown in Table 1 and Table 2, respectively.

[0068] Table 1 Group components after reaction of different catalysts

[0069]

[0070] As can be seen from Table 1, the total amount of light components (saturates and aromatics) in Examples 4-6 increased, indicating that the addition of the catalytic-emulsion composite viscosity reduction system can effectively achieve catalytic upgrading. The difference between Example 4 and Comparative Example 2 is that an emulsion system was added. The addition of the emulsion system can effectively reduce the apparent viscosity of the heavy oil and achieve upgrading effect, so there is a large difference in viscosity.

[0071] Table 2 Viscosity comparison after reaction of different catalysts (40°C)

[0072]

[0073] As can be seen from Table 1 and Table 2, the organic peroxide oxidant is compounded with an emulsifier to configure an oil-in-water emulsion system, and a certain amount of catalyst is dispersed in the water of the emulsion to construct a catalytic oxidation system, which is superior to the system without catalyst and the system without emulsion in terms of upgrading effect and viscosity reduction rate.

[0074] The above embodiments are only used to illustrate the present application, and are not intended to limit the present application. Although the present application has been described in detail with reference to the examples, it should be understood by those skilled in the art that various combinations, modifications or equivalent replacements of the technical solutions of the present application do not deviate from the spirit and scope of the present application, and should be covered in the scope of the claims of the present application.

Claims

1. A dual-function, heavy oil catalytic viscosity reducing composition characterized by: The catalytic-emulsion composite viscosity reducing composition is prepared by mixing the catalyst and the oxidant and adjusting the HLB value to 7-14 by using the surfactant, wherein the catalyst is the amphiphilic TM / C-NH2 nanoparticle, and the oxidant is the organic peroxide; The amphiphilic TM / C-NH2 nanoparticle is the carbon nanosphere particle loaded with 0-valence transition metal and amino group; The organic peroxide is any one of hydroperoxide, dialkyl peroxide, diacyl peroxide, peroxy ester, peroxide carbonate and ketone peroxide; The surfactant is the composite surfactant composed of hydrophilic surfactant and oleophilic surfactant; In the dual-functional thick oil catalytic viscosity reducing composition, the mass ratio of the catalyst to the oxidant is 1:1-1:

3.

2. The dual function heavy oil catalytic viscosity reducing composition of claim 1, wherein: The organic peroxide is peroxyl benzoic acid, benzoyl peroxide or hydrogen peroxide.

3. The dual functional heavy oil catalytic viscosity reducing composition of claim 1, wherein: The hydrophilic surfactant and the oleophilic surfactant are both non-ionic surfactants.

4. The dual function heavy oil catalytic viscosity reducing composition of claim 1, wherein: The preparation method of the TM / C-NH2 nanoparticle is as follows: Synthesizing carbon nanosphere particle; Loading 0-valence transition metal; Grafting -NH2 on the surface of the carbon nanosphere particle by amino functionalization.

5. A method for reducing the viscosity of heavy oil using the bifunctional heavy oil catalytic viscosity-reducing composition according to any one of claims 1-4, characterized in that, The method comprises the following steps: Mixing the catalyst and the oxidant and then adding the surfactant to obtain the catalytic-emulsion composite viscosity reducing composition; Mixing the catalytic-emulsion composite viscosity reducing composition with thick oil and then heating to the reservoir environment temperature for reaction, and completing the viscosity reduction of the thick oil after the reaction is finished.

6. The method of claim 5, wherein the viscosity of the heavy oil is reduced by: The addition amount of the catalytic-emulsion composite viscosity reducing composition, calculated by the catalyst, is 0.01%-1% of the mass of the thick oil.

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