Plasma enhanced catalytic coated proppant and method of making and using same
Catalytic coating proppant was prepared at low temperature using a plasma-enhanced preparation method, which solved the problems of high energy consumption during high-temperature calcination and easy coating peeling, and achieved efficient viscosity reduction and long-term flow conduction of heavy oil.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- DALIAN MARITIME UNIVERSITY
- Filing Date
- 2026-03-02
- Publication Date
- 2026-06-09
AI Technical Summary
Existing catalytic proppant preparation technologies require high-temperature calcination, have high energy consumption, are prone to coating peeling, and have insufficient catalytic active sites, resulting in low heavy oil extraction efficiency.
A plasma-enhanced preparation method is adopted, in which transition metal salts are attached to the surface of the support by impregnation or spraying. The plasma discharge treatment is used to transform the support into a catalytic active layer with lattice defects at low temperature, forming a mechanically interlocked structure, thus avoiding high-temperature sintering and coating peeling.
It significantly reduces energy consumption, improves catalytic activity, enhances catalyst dispersion and long-term flowability, and improves the viscosity reduction effect of heavy oil.
Abstract
Description
Technical Field
[0001] This invention relates to the field of oil and gas field development and catalytic materials technology, specifically to a plasma-enhanced catalytic coating support agent, its preparation method, and its application. Background Technology
[0002] my country possesses abundant heavy oil reserves, but these crude oils generally exhibit high viscosity, high density, low hydrogen-to-carbon ratio, and poor fluidity, leading to significant extraction difficulties and low recovery rates. Currently used conventional thermal recovery technologies (such as steam injection and steam drive), while technologically mature, face bottlenecks such as low thermal utilization and limited recovery rates (typically only 15%–25%). Furthermore, a single thermal recovery method cannot fundamentally alter the heavy component structure of heavy oil, resulting in a sharp decline in the oil-to-steam ratio in the later stages of development.
[0003] To overcome the limitations of single technologies, in-situ catalytic reforming of heavy oil has gradually become a research hotspot. This technology involves injecting a catalyst into the formation, which, under the high temperature and pressure of steam injection, induces a hydrothermal cracking reaction in the heavy oil, converting large-molecule asphaltenes and gums into smaller-molecule saturated hydrocarbons and aromatics with better flowability, thereby achieving irreversible viscosity reduction of the heavy oil. Meanwhile, fracturing technology is a key means to improve the permeability of low-permeability heavy oil reservoirs. Preparing "functionalized proppants" by loading catalysts onto the surface of fracturing proppants, thus integrating "fracture creation" and "in-situ catalysis," is a highly promising technological direction.
[0004] However, existing catalytic proppant preparation technologies mainly employ the traditional "wet impregnation-thermochemical calcination" process. This process not only consumes a large amount of energy and has low production efficiency due to the need for prolonged heating to 300℃~500℃, but also easily induces sintering and agglomeration of the supported nano-metal particles during high-temperature heat treatment, significantly reducing the specific surface area and active site exposure rate of the catalyst. At the same time, since this process mainly relies on simple physical impregnation and thermal drying, there is only a weak physical adsorption between the catalytic active layer and the proppant matrix. Under the high shear environment of fracturing pumping and high formation closure pressure, the coating is prone to peeling and loss, leading to rapid failure of catalytic function. In addition, metal oxides prepared under thermal equilibrium conditions usually have a perfect lattice and low defect concentration, while surface defects such as oxygen vacancies are important active sites for low-temperature catalytic reactions, thus their low-temperature catalytic efficiency is often limited. Summary of the Invention
[0005] This invention addresses the technical bottlenecks in existing catalytic proppant preparation technologies, such as the need for high-temperature calcination, high energy consumption, easy coating detachment, and insufficient catalytic active sites. It researches and designs a plasma-enhanced catalytic coating proppant, its preparation method, and its applications. The technical means employed in this invention are as follows:
[0006] A method for preparing a plasma-enhanced in-situ modified catalytic coating support, characterized by comprising the following steps: S1: The transition metal salt is uniformly attached to the surface of the proppant matrix by impregnation, spraying or co-precipitation, and then dried to obtain the coating precursor. S2: The coating precursor is subjected to plasma discharge treatment to convert the transition metal salt in situ into a catalytically active layer containing lattice defects, thereby obtaining a plasma-enhanced in-situ modified catalytic coating support.
[0007] Furthermore, in step S1, the soaking time is 2 to 24 hours, preferably 12 hours; in the drying step, the following parameters are controlled according to different drying methods: if blower drying is used, the drying temperature is 80 to 120°C and the time is 2 to 8 hours; if microwave drying is used, the microwave power is 500 to 1500W and the time is 10 to 20 minutes.
[0008] Further, in step S1, the transition metal salt is selected from one or more of the nitrates, carbonates, organic acid salts, ammonium salts or chlorides of nickel, copper, iron, molybdenum, cobalt, and manganese, and the molar concentration of the transition metal salt solution is 0.1 mol / L to 5.0 mol / L; in step S2, the coating precursor is placed in a non-equilibrium plasma reactor for discharge treatment, the bulk temperature of the support is controlled below 200℃, and the non-thermal effect of plasma is used to induce crystal growth and surface modification.
[0009] Furthermore, the proppant matrix is quartz sand, ceramsite, or sintered bauxite, with a particle size range of 75~8000μm.
[0010] Furthermore, the proppant matrix is 20-40 mesh (380-830 μm) quartz sand.
[0011] Furthermore, the non-equilibrium plasma reactor is a dielectric barrier discharge (DBD) reactor, a jet discharge reactor, a glow discharge reactor, or a sliding arc discharge reactor (when the particle size of the proppant matrix is 300 μm to 8000 μm, a flat-plate dielectric barrier discharge (DBD) reactor is used; when the particle size of the proppant matrix is 75 μm to 300 μm, a plasma jet discharge reactor is used).
[0012] Further, in step S2, the plasma discharge treatment is carried out in an oxidizing atmosphere or a reducing atmosphere, wherein the oxidizing atmosphere is selected from oxygen, air or ozone; the reducing atmosphere is selected from hydrogen, ammonia or a mixture thereof with an inert gas, wherein the inert gas is selected from one or more of argon, helium and nitrogen.
[0013] Furthermore, the plasma discharge treatment is carried out in a reducing atmosphere, which is a hydrogen-argon mixture, wherein the volume percentage of hydrogen in the hydrogen-argon mixture is 5% to 20%, so as to induce a high concentration of surface oxygen vacancies on the surface of the catalytic active layer, preferably with a gas flow rate of 50 to 200 mL / min.
[0014] Further, in step S2, the discharge power supply is an AC power supply, a DC power supply, or a pulse power supply, preferably an AC power supply; the discharge parameters are as follows: discharge power 50~500W, discharge frequency 1~20kHz (preferably 1~5 kHz), electrode spacing 2~10mm (preferably 2~6 mm), and processing time 1~60min (preferably 5~15min).
[0015] A plasma-enhanced in-situ modified catalytic coating support prepared by the method described in this invention, wherein the catalytic active layer forms a mechanically interlocked structure with the support substrate surface through plasma etching; the surface of the catalytic active layer is rich in coordination unsaturated metal sites and oxygen vacancy defects.
[0016] The present invention discloses the application of a plasma-enhanced in-situ modified catalytic coating proppant in heavy oil thermal recovery. The proppant is injected into the formation as a fracturing proppant along with fracturing fluid, with an injection ratio of water to proppant mass of 30:1 to 100:1. During the steam injection thermal recovery stage, the proppant is used to catalyze the hydrothermal cracking reaction of underground heavy oil in situ using a heat source of 180°C to 350°C (preferably 290°C) provided by steam injection, thereby reducing the viscosity of the heavy oil.
[0017] Compared with existing technologies, this invention utilizes cold plasma technology to replace traditional high-temperature thermal calcination, enabling rapid catalyst preparation in a low-temperature environment. This significantly reduces energy consumption and shortens the preparation cycle, effectively preventing the sintering and growth of metal particles caused by high temperatures and significantly improving the dispersion of active components. Simultaneously, the high-energy electrons and active particles generated by plasma discharge bombard the catalyst surface, breaking the thermodynamic equilibrium constraint and creating a large number of lattice oxygen vacancies and coordination unsaturated sites in situ. These sites serve as active centers for the hydrothermal cracking of heavy oil, significantly reducing the activation energy and greatly improving the viscosity reduction effect. Furthermore, the physical etching effect of plasma on the proppant surface increases surface roughness, forming a strong mechanical interlocking structure between the catalytic active layer and the substrate. This effectively solves the problem of easy detachment of coatings in traditional impregnation methods under high-shear conditions during fracturing, ensuring long-term conductivity. Detailed Implementation
[0018] This invention provides a plasma-enhanced in-situ modified catalytic film support, its preparation method, and its application. This method utilizes a combination of "precursor loading" and "plasma modification" to prepare a highly active catalytic support rich in defects under mild conditions. The general preparation steps are as follows: S1. Precursor loading: Transition metal salts are uniformly attached to the surface of a proppant matrix (quartz sand, ceramsite, etc.) with a certain particle size range (e.g., 20-40 mesh) using impregnation, spraying, or co-precipitation methods, and then dried to obtain the coated precursor. When using the impregnation method, the proppant matrix is immersed in an aqueous solution containing transition metal salts, and the impregnation time is controlled (6-24 hours) to allow the metal ions to be fully adsorbed and penetrate into the micropores on the proppant surface. Excess solution is then removed by filtration, and the matrix is dried in a forced-air drying oven or microwave equipment to obtain an intermediate loaded with a precursor film layer. When using the spray method, the proppant matrix is placed in a rotary coating machine, and the transition metal salt solution is uniformly sprayed onto the surface of the proppant matrix using an atomizing nozzle while it is continuously rotating. When using the precipitation method, the proppant matrix is mixed with a transition metal salt solution, and a precipitant is added to induce the transition metal salt to precipitate on the surface of the proppant matrix, where it undergoes in-situ heterogeneous nucleation and growth.
[0019] S2. Plasma Modification Treatment: The dried coated precursor is placed in a non-equilibrium plasma reactor. The reactor type is selected based on the proppant particle size; millimeter-sized particles are spread between DBD plates, while micron-sized powder is placed below the jet nozzle or in a fluidized bed. A specific working gas (oxidizing or reducing) is introduced, initiating gas discharge under the influence of an electric field to generate low-temperature plasma. High-energy electrons, ions, and active free radicals in the plasma bombard and chemically react with the precursor layer, inducing in-situ decomposition and crystallization of the precursor, etching the proppant surface to form a mechanically interlocked structure, and simultaneously introducing a large number of oxygen vacancy defects into the crystal lattice, ultimately obtaining the proppant.
[0020] S3. Heavy Oil Thermal Recovery Application: The prepared catalytically coated proppant is pumped into the fractures of the underground heavy oil reservoir along with fracturing fluid. In the subsequent steam injection thermal recovery stage, the high temperature and pressure environment of the formation allows the catalytically active sites on the proppant surface to catalyze the hydrothermal cracking reaction of the flowing heavy oil in situ, achieving viscosity reduction and increased production.
[0021] Example 1 This embodiment prepares a NiO-coated quartz sand catalyst support.
[0022] Step S1: Dissolve 10 g of nickel nitrate hexahydrate in 90 g of deionized water to prepare a 10% nickel nitrate solution. Add 50 g of quartz sand with a particle size of 0.35~0.85 mm (20~40 mesh) and let it stand at room temperature for 12 hours to soak. Filter to remove residual liquid, and dry in a 100 ℃ forced-air drying oven for 3 hours to obtain the precursor coated quartz sand.
[0023] Step S2: Place the dried precursor in a flat-plate dielectric barrier discharge (DBD) reactor. Introduce air as the working gas at a flow rate of 100 mL / min. Adjust the AC power supply parameters: discharge power 100 W, frequency 3 kHz, electrode spacing 5 mm. Processing time 10 min.
[0024] Step S3: Inject the prepared proppant into the sand-filled tube model at a water-to-proppant mass ratio of 30:1, and conduct a heavy oil displacement experiment under simulated steam injection conditions at 250℃.
[0025] Results: The viscosity reduction rate of heavy oil was 80.3%. After upgrading, the oil sample density decreased by 2.1%, the total content of resinous asphaltenes decreased by 13.7%, and the content of saturated hydrocarbons and aromatic hydrocarbons increased by 12.8%.
[0026] Example 2 This embodiment explores the effect of a reducing atmosphere on enhancing catalytic activity.
[0027] Step S1: Same as in Example 1.
[0028] Step S2: During plasma treatment, the working gas is changed to a hydrogen-argon mixture (10% H2 + 90% Ar), and the other parameters are the same as in Example 1.
[0029] Step S3: Same as in Example 1.
[0030] Results: The viscosity reduction rate of heavy oil increased to 90.3%. Asphaltenes decreased by 17.5%, while saturated and aromatic hydrocarbons increased by 17.1%. Compared with air atmosphere, reducing atmosphere treatment significantly improved the viscosity reduction effect.
[0031] Example 3 Step S1: Dissolve 4.4 g of ammonium molybdate tetrahydrate in 50 g of water. Add 50 g of quartz sand, soak for 12 hours, and then dry.
[0032] Step S2: Place the coated precursor in the DBD reactor. To verify the treatment effect at low power, adjust the electrode spacing to 2 mm. Use AC power, discharge power of 50 W, and discharge frequency of 1 kHz. Due to the low power, extend the treatment time to 60 min to ensure complete precursor conversion.
[0033] Step S3: Same as in Example 1.
[0034] Results: The viscosity reduction rate of heavy oil was 85.7%. Asphaltene and resin content decreased by 15.3%, while saturated and aromatic hydrocarbon content increased by 14.9%.
[0035] Example 4 Step S1: Dissolve 12.08g of copper nitrate trihydrate in 50g of water. Add 50g of quartz sand with a particle size of 0.21~0.35mm (40~70 mesh), soak for 12 hours, and then dry.
[0036] Step S2: Place the precursor in a DC glow discharge reactor. Set the electrode spacing to 6 mm. Connect the high-voltage DC power supply, adjust the discharge power to 120 W, and the processing time to 15 min.
[0037] Step S3: Same as in Example 1.
[0038] Results: The viscosity reduction rate of heavy oil was 81.7%. Asphaltene and resin content decreased by 11.3%, while saturated and aromatic hydrocarbon content increased by 10.9%.
[0039] Example 5 Step S1: Dissolve 4.5g of nickel nitrate hexahydrate and 6.1g of copper nitrate trihydrate in 50g of water to prepare a mixed solution. Add 50g of quartz sand and soak for 12 hours, then dry.
[0040] Step S2: Air atmosphere plasma treatment, parameters are the same as in Example 1.
[0041] Step S3: Same as in Example 1.
[0042] Results: The viscosity reduction rate of heavy oil was 88.5%. The synergistic effect of bimetallic compounds was better than that of monometallic compounds.
[0043] Example 6 Step S1: Dissolve 4.5g of nickel nitrate hexahydrate and 2.2g of ammonium molybdate tetrahydrate in 50g of water. Add 50g of quartz sand and soak for 12 hours, then dry.
[0044] Step S2: Place the precursor in a high-power DBD reactor. Adjust the electrode spacing to 10 mm. Use an AC power supply to increase the discharge power to 500 W and the discharge frequency to 20 kHz. Utilize the strong bombardment effect of high-frequency, high-energy plasma to shorten the processing time to 1 minute, achieving rapid preparation.
[0045] Step S3: Same as in Example 1.
[0046] Result: The viscosity reduction rate of heavy oil was 92.3%.
[0047] Example 7 Step S1: Dissolve 3.0g of copper nitrate trihydrate, 3.0g of nickel nitrate hexahydrate, and 2.0g of ammonium molybdate tetrahydrate in 50g of water. Add 50g of quartz sand and soak for 12 hours, then dry.
[0048] Step S2: Hydrogen-argon mixed gas plasma treatment (same as Example 2).
[0049] Step S3: Same as in Example 1.
[0050] Results: The viscosity reduction rate of heavy oil reached as high as 97.3%. Asphaltene and resin content decreased by 22.4%, while saturated and aromatic hydrocarbon content increased by 21.5%.
[0051] Example 8 This embodiment focuses on modifying small-particle-size ceramic proppant (particle size range 75~150μm) to explore the effect of plasma jet on the treatment of fine particles.
[0052] Step S1: Dissolve 8.0g of nickel nitrate hexahydrate and 2.0g of copper nitrate trihydrate in 90g of deionized water to prepare a mixed precursor solution. Add 50g of fine ceramic particles with a particle size of 100-200 mesh (75-150μm) and impregnate with magnetic stirring at room temperature for 12 hours. After removing excess liquid by filtration, place in a microwave drying oven and dry at 800W for 15 minutes to obtain the film-coated precursor powder.
[0053] Step S2: Place the dried powder 10 mm directly below the quartz nozzle of the atmospheric pressure plasma jet (APPJ) device. Use argon as the working gas, and control the gas flow rate at 3 L / min. Turn on the AC power supply, adjust the discharge power to 200 W, and the processing time to 5 min.
[0054] Results: The prepared micro-supporting agent was mixed with heavy oil and reacted at 250℃ for 24 hours under hydrothermal conditions. The viscosity reduction rate of the heavy oil was measured to be 89.2%. SARA four-component analysis showed that the total content of resins and asphaltenes decreased by 16.8%, confirming that the micron-sized particles maintained extremely high catalytic activity under jet treatment.
[0055] Example 9 This embodiment uses a spray method to prepare Ni-Co bimetallic catalytic coating proppant, aiming to improve the uniformity of the distribution of active components on the proppant surface and reduce waste liquid discharge.
[0056] Step S1: Dissolve 5.8g of nickel nitrate hexahydrate and 5.8g of cobalt nitrate hexahydrate in 30g of deionized water to prepare a high-concentration metal salt solution. Place 100g of quartz sand with a particle size of 0.425~0.85mm (20~40 mesh) in a rotary coating machine. Under 80℃ hot air blowing and continuous rolling conditions, use an atomizing nozzle to uniformly spray the above metal salt solution onto the surface of the quartz sand. After spraying, continue rolling and drying for 30 minutes to obtain a preform with a uniform pink coating.
[0057] Step S2: Place the dried precursor in the DBD reactor. Introduce argon gas (flow rate 150 mL / min). Use a nanosecond pulse power supply, which is beneficial for generating high-energy electrons at relatively low gas temperatures. Discharge parameters: average power 150 W, frequency 5 kHz, electrode spacing 4 mm, processing time 8 min.
[0058] Results: The prepared proppant was subjected to heavy oil hydrothermal pyrolysis experiments under the conditions described in Example 1. The viscosity reduction rate of the heavy oil was measured to be 87.6%.
[0059] Example 10 In this embodiment, Fe-Mn composite oxide coating support is prepared by in-situ co-precipitation method, aiming to increase the loading of active components and specific surface area.
[0060] Step S1: Dissolve 8.1g of ferric nitrate nonahydrate and 3.6g of manganese chloride tetrahydrate in 100g of deionized water. Add 50g of ceramsite support agent (particle size 0.45~0.9mm) and stir until homogeneous. Under vigorous stirring, slowly add 1.0mol / L sodium carbonate solution as a precipitant to adjust the pH to 9~10, inducing iron and manganese ions to co-precipitate in situ on the surface of the ceramsite to form a reddish-brown precursor coating layer. After filtration, wash three times with deionized water and dry at 100℃ for 4 hours.
[0061] Step S2: Place the coating precursor in a DBD reactor and introduce a hydrogen-argon mixture (10% H2 + 90% Ar) at a flow rate of 100 mL / min. The discharge power is 200 W, and the treatment time is 12 min. The reducing plasma transforms the surface hydroxide / carbonate precipitate into a defect-rich Fe-Mn composite oxide layer.
[0062] The prepared proppant was subjected to heavy oil hydrothermal pyrolysis experiments under the conditions described in Example 1.
[0063] Results: The viscosity reduction rate of heavy oil reached 93.1%. SARA analysis showed that the conversion rate of asphaltenes was significant, with a reduction of 19.2%.
[0064] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.
Claims
1. A method for preparing a plasma-enhanced in-situ modified catalytic coating support, characterized in that, Includes the following steps: S1: The transition metal salt is uniformly attached to the surface of the proppant matrix by impregnation, spraying or co-precipitation, and then dried to obtain the coating precursor; S2: The coating precursor is subjected to plasma discharge treatment to convert the transition metal salt in situ into a catalytically active layer containing lattice defects, thereby obtaining a plasma-enhanced in-situ modified catalytic coating support.
2. The preparation method of the plasma-enhanced in-situ modified catalytic coating support according to claim 1, characterized in that, In step S1, the transition metal salt is selected from one or more of the following: nitrates, carbonates, organic acid salts, ammonium salts, or chlorides of nickel, copper, iron, molybdenum, cobalt, and manganese. The molar concentration of the transition metal salt solution is 0.1 mol / L to 5.0 mol / L. In step S2, the coating precursor is placed in a non-equilibrium plasma reactor for discharge treatment. The bulk temperature of the support is controlled below 200°C. The non-thermal effect of plasma is used to induce crystal growth and surface modification.
3. The preparation method of the plasma-enhanced in-situ modified catalytic coating support according to claim 1, characterized in that, The proppant matrix is quartz sand, ceramsite, or sintered bauxite, with a particle size range of 75~8000μm.
4. The preparation method of the plasma-enhanced in-situ modified catalytic coating support according to claim 3, characterized in that, The proppant matrix is 20-40 mesh quartz sand.
5. The method for preparing the plasma-enhanced in-situ modified catalytic coating support according to claim 2, characterized in that, The non-equilibrium plasma reactor is a self-dielectric barrier discharge reactor, a jet discharge reactor, a glow discharge reactor, or a sliding arc discharge reactor.
6. The preparation method of the plasma-enhanced in-situ modified catalytic coating support according to claim 1, characterized in that, In step S2, the plasma discharge treatment is carried out in an oxidizing atmosphere or a reducing atmosphere, wherein the oxidizing atmosphere is selected from oxygen, air or ozone; the reducing atmosphere is selected from hydrogen, ammonia or a mixture of hydrogen and an inert gas, wherein the inert gas is selected from one or more of argon, helium and nitrogen.
7. The preparation method of the plasma-enhanced in-situ modified catalytic coating support according to claim 6, characterized in that, The plasma discharge treatment is carried out in a reducing atmosphere, which is a hydrogen-argon mixture, wherein the volume percentage of hydrogen in the hydrogen-argon mixture is 5% to 20%.
8. The method for preparing the plasma-enhanced in-situ modified catalytic coating support according to claim 1, characterized in that, In step S2, the discharge power supply is an AC power supply, a DC power supply, or a pulse power supply; the discharge parameters are as follows: discharge power 50~500W, discharge frequency 1~20kHz, electrode spacing 2~10mm, and processing time 1~60min.
9. A plasma-enhanced in-situ modified catalytic coating support, characterized in that, It is prepared by the method described in any one of claims 1 to 8.
10. The application of the plasma-enhanced in-situ modified catalytic coating proppant as described in claim 9 in heavy oil thermal recovery, characterized in that, The proppant is injected into the formation as a fracturing proppant along with the fracturing fluid, with an injection ratio of water to proppant mass of 30:1 to 100:
1. During the steam injection thermal recovery stage, the proppant is used to catalyze the hydrothermal cracking reaction of the underground heavy oil in situ using a heat source of 180℃ to 350℃ provided by the steam injection, thereby reducing the viscosity of the heavy oil.