Method for preparing graphene from catalytically cracked oil-based drill cuttings and application thereof

Abstract

The present application relates to the technical field of drilling fluid recycling, in particular to a method for preparing graphene from catalytic cracking oil-based drill cuttings and application thereof.The recycling method comprises the following steps: S1, pretreatment of oil-based drill cuttings; S2, catalytic cracking; S3, surface modification of graphene.The present application breaks through the technical bottleneck of easy sintering and carbon deposition inactivation of traditional single metal catalyst (Fe, Ni, etc.) through high-entropy alloy multi-element synergistic catalysis, improves the catalytic efficiency, realizes the resource utilization of drill cuttings at the same time, greatly reduces the environmental pollution risk, and forms an economic-environmental system of "drill cuttings-graphene-drilling fluid-drill cuttings".The composition of high-entropy alloy can be flexibly adjusted to adapt to different formation requirements;the surface functionalization modification of graphene can further expand its multifunctional application in drilling fluid.

Description

Technical Field

[0001] This invention relates to the field of drilling fluid recycling technology, specifically to a method and application for preparing graphene by catalytic cracking of oil-based drill cuttings. Background Technology

[0002] Oil-based drilling fluids are widely used in drilling through complex formations due to their excellent resistance to high temperatures and salt calcium intrusion. However, the resulting oil-based drill cuttings have a high oil content (10-30%), and traditional treatment methods (landfilling, incineration) pose environmental pollution risks and waste resources. Graphene can significantly improve lubrication and plugging properties in drilling fluids, but existing preparation methods (such as chemical vapor deposition) rely on high-purity carbon sources, resulting in high costs and lacking integration with waste resource utilization. High-entropy alloys (HEAs) exhibit unique advantages in catalysis due to their multi-element synergistic effects and high-temperature stability, forming abundant active sites. However, their application in oil-based drill cuttings pyrolysis and drilling fluids has not yet been reported. Summary of the Invention

[0003] To address the shortcomings of existing technologies, the present invention aims to provide a method and application for preparing graphene by catalytic cracking of oil-based drill cuttings. This achieves efficient resource utilization of oil-based drill cuttings, reducing environmental pollution; reduces the cost of preparing high-performance graphene through high-entropy alloy catalytic cracking technology; and constructs a "drill cuttings-graphene-drilling fluid-drill cuttings" recycling system to improve drilling fluid performance and reduce costs. The present invention utilizes oil-based drill cuttings waste generated during drilling as raw material, uses a high-entropy alloy as a catalyst, and performs high-temperature cracking of the carbon-containing solid phase in oil-based drill cuttings under a nitrogen atmosphere to prepare high-performance graphene, which is then recycled into the drilling fluid recycling system.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] A method for preparing graphene by catalytic cracking of oil-based drill cuttings includes the following preparation steps:

[0006] S1. Oil-based drill cuttings pretreatment: The liquid phase (carbon exists in the form of alkanes and cycloalkanes) and solid phase (carbon mainly consists of base oil adsorbed on the surface of drill cuttings particles and organic matter from the formation) in oil-based drill cuttings are separated by centrifugation. The liquid phase is purified by distillation and reused in drilling fluid base oil. Low molecular weight hydrocarbons in the solid phase are removed by extraction modification liquid. The resulting solid is then soaked in extraction modification liquid and filtered to obtain a high carbon content solid phase.

[0007] S2. Catalytic cracking: By mass, 1-2 parts of nano-alloy particles are mixed with 10-30 parts of carbon-containing solid phase in a tube furnace, nitrogen is introduced, the temperature is raised to 800-1200℃ and held for 30-120 min to generate graphene.

[0008] S3. Graphene surface modification: Wash graphene with a 20-25% hydrochloric acid solution, then disperse it in anhydrous ethanol and sonicate for 25-30 min until uniformly suspended. Slowly add 8-10 parts of modified surface modifier, and react with magnetic stirring at 300-400 r / min in a water bath at 58-62℃ for 4-5 h. After centrifugation, washing and drying, the modified graphene is obtained.

[0009] The preparation of the extraction modified solution includes the following steps:

[0010] S11. By weight, add 3-5 parts of pyridine and 1-3 parts of tributyl phosphate to 80-100 parts of n-hexane, and stir for 10-15 minutes at a speed of 300-400 r / min in a water bath at 38-40℃ to obtain a preliminary extract.

[0011] S12. Add 1-2 parts sodium dodecylbenzenesulfonate, 1.2-1.5 parts ferric acetylacetone and 1.5-2 parts oleic acid to the preliminary extract, and ultrasonically disperse at a frequency of 40 kHz for 20-30 min to obtain the modified extract.

[0012] Preferably, the preparation of nano-alloy particles includes the following steps:

[0013] S21. By weight, 45-50 parts of alloy metal powder and 0.8-1 parts of stearic acid are added to a high-energy ball mill to obtain mixed alloy particles;

[0014] S22. Evacuate the ball mill and introduce argon gas. Ball mill for 20-24 hours in a cycle mode of 25-30 min ball milling followed by 10-15 min pause cooling to obtain nano-alloy particles.

[0015] Preferably, the preparation of the modified surface modifier includes the following steps:

[0016] S31. By weight, dissolve 0.5-1 parts of γ-(methacryloyloxy)propyltrimethoxysilane and 0.3-0.5 parts of hexadecyltrimethoxysilane in 7-8 parts of anhydrous ethanol, and stir at 300-350 r / min for 5-10 min.

[0017] S32. Add 0.5-0.8 parts of deionized water to the mixture obtained in step S31, and adjust the pH of the solution to 4-5 using acetic acid. Stir at 300-350 r / min for 20-30 min to obtain the modified surface modifier.

[0018] Preferably, in step S1, the centrifugation speed is 2500-3000 rpm and the time is 15-20 min.

[0019] Preferably, the mass ratio of graphene to anhydrous ethanol in step S3 is 1:100.

[0020] Preferably, the alloy metal powder is composed of two or more of copper, nickel, cobalt, manganese, zinc, iron, tin, and bismuth.

[0021] Preferably, in step S22, the ball-to-material mass ratio in the ball mill is 15:1, and the ball mill speed is 300-350 rpm.

[0022] Preferably, in step S1, the mass ratio of the extraction modified liquid to the solid is 3:1, and the soaking time is 1-2 hours.

[0023] Preferably, the frequency of ultrasonic treatment in step S3 is 40 kHz.

[0024] The modified graphene prepared according to the above preparation method is used in the recycling of drilling fluid. The application is characterized in that the modified graphene is added to oil-based drilling fluid at 0.1-0.5% (the mass of modified graphene accounts for 0.1-0.5% of the total mass of oil-based drilling fluid) to form graphene-enhanced drilling fluid. Then, the oil-based drill cuttings formed after the graphene-enhanced drilling fluid is put into use are recycled to prepare modified graphene for reuse, thus forming a cycle.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] 1. This invention overcomes the technical bottlenecks of traditional single-metal catalysts (Fe, Ni, etc.) that are prone to sintering, carbon deposition, and deactivation through the synergistic catalytic effect of multi-element high-entropy alloys, thereby improving catalytic efficiency. Simultaneously, it enables the resource utilization of drill cuttings, significantly reducing environmental pollution risks and forming an economical and environmentally friendly system of "drill cuttings-graphene-drilling fluid-drill cuttings". The composition of the high-entropy alloy can be flexibly adjusted to adapt to different formation requirements; the functional modification of the graphene surface can further expand its multifunctional applications in drilling fluids.

[0027] 2. This invention reduces the energy barrier of the pyrolysis reaction through the synergistic effect of the extraction modification liquid, nano-alloy particles, and modified surface modifier, promotes the ordered graphitization of carbon source, significantly improves the yield and crystallinity of graphene, and better endows graphene with perfect interfacial properties as a drilling fluid additive, enabling it to be uniformly and stably dispersed in the drilling fluid and fully exert its lubrication, plugging and other functions.

[0028] 3. When added to drilling fluid, this invention can significantly improve the lubricity and filtration properties of the drilling fluid, reduce frictional torque, form a dense sealing layer on the well wall, enhance sealing performance, and effectively address the problem of well wall instability. It is especially suitable for drilling deep and ultra-deep wells in unconventional oil and gas resources. Attached Figure Description

[0029] Figure 1 This is a process flow diagram for preparing graphene from oil-based drill cuttings by catalytic cracking, as described in this invention.

[0030] Figure 2 This is a flow chart of the preparation process of the extraction modified liquid of the present invention;

[0031] Figure 3 This is a flowchart illustrating the preparation process of the nano-alloy particles of the present invention.

[0032] Figure 4 This is a process flow diagram for preparing the modified surface modifier of the present invention;

[0033] Figure 5 This is the SEM image of the modified graphene obtained in Example 1 of the present invention. Detailed Implementation

[0034] The present invention will now be clearly and completely described in conjunction with embodiments thereof. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0035] Please see Figure 1-5 The present invention provides a technical solution:

[0036] Example 1

[0037] A method for preparing graphene by catalytic cracking of oil-based drill cuttings:

[0038] Before preparing graphene from oil-based drill cuttings through catalytic cracking, the following steps are taken: preparation of extraction modification solution, nano-alloy particles, and surface modifiers.

[0039] The preparation of the extraction modified solution includes the following steps:

[0040] S11. Add 3g of pyridine and 1g of tributyl phosphate to 80g of n-hexane, and stir at 300r / min for 10min in a water bath at 38℃ to obtain a preliminary extract.

[0041] S12. Add 1g sodium dodecylbenzenesulfonate, 1.2g iron acetylacetone and 1.5g oleic acid to the preliminary extract, and ultrasonically disperse at a frequency of 40kHz for 20min to obtain the modified extract;

[0042] The preparation of nano-alloy particles includes the following steps:

[0043] S21. Add 45g of alloy metal powder (composed of copper, iron and bismuth in equal parts by mass) and 0.8g of stearic acid to a high-energy ball mill to obtain mixed alloy particles;

[0044] S22. Evacuate the ball mill and introduce argon gas. Ball mill in a cycle mode of 25 min ball milling followed by 10 min pause cooling (ball-to-material mass ratio of 15:1, ball mill speed of 300 rpm) for 20 h to obtain nano-alloy particles.

[0045] The preparation of modified surface modifiers includes the following steps:

[0046] S31. Dissolve 0.5g γ-(methacryloyloxy)propyltrimethoxysilane and 0.3g hexadecyltrimethoxysilane in 7ml anhydrous ethanol and stir at 300r / min for 5min.

[0047] S32. Add 0.5 ml of deionized water to the mixture obtained in step S31, and adjust the pH of the solution to 4 using acetic acid. Stir at 300 r / min for 20 min to obtain the modified surface modifier.

[0048] S1. Pretreatment of oil-based drill cuttings: The liquid phase (carbon exists in the form of alkanes and cycloalkanes) and the solid phase (carbon mainly consists of base oil adsorbed on the surface of drill cutting particles and organic matter from the formation) of oil-based drill cuttings (composed of base oil, rock particles and organic and inorganic additives) are separated by centrifugation (2500 rpm, 15 min). The liquid phase is purified by distillation and reused for drilling fluid base oil. Low molecular weight hydrocarbons in the solid phase are removed by extraction modification liquid. The extraction modification liquid and the solid phase are then soaked in a 3:1 ratio for 1 h. After filtration, a high carbon content solid phase is obtained.

[0049] S2. Catalytic pyrolysis: 1g of nano-alloy particles are mixed with 10g of carbon-containing solid phase in a tube furnace, nitrogen gas is introduced, the temperature is raised to 800℃ and held for 30min to generate graphene.

[0050] S3. Graphene surface modification: Graphene was washed with a 20% hydrochloric acid solution and then dispersed in anhydrous ethanol (1:100 ratio) and sonicated at 40kHz for 25 minutes until uniform suspension. 8g of modified surface modifier was slowly added and the mixture was magnetically stirred at 300r / min in a water bath at 58-62℃ for 4 hours. After centrifugation, washing and drying, modified graphene was obtained.

[0051] S4. Drilling fluid preparation: Add 0.1% modified graphene to oil-based drilling fluid to form graphene-enhanced drilling fluid;

[0052] S5. Recycling: During the drilling process, the used drilling fluid containing drill cuttings is recovered and steps S1-S4 are repeated to form a recycling system.

[0053] Example 2

[0054] A method for preparing graphene by catalytic cracking of oil-based drill cuttings:

[0055] Before preparing graphene from oil-based drill cuttings through catalytic cracking, the following steps are taken: preparation of extraction modification solution, nano-alloy particles, and surface modifiers.

[0056] The preparation of the extraction modified solution includes the following steps:

[0057] S11. Add 5g pyridine and 3g tributyl phosphate to 100g n-hexane, and stir at 400r / min for 15min in a 40℃ water bath to obtain a preliminary extract.

[0058] S12. Add 2g sodium dodecylbenzenesulfonate, 1.5g iron acetylacetone and 2g oleic acid to the preliminary extract, and ultrasonically disperse at a frequency of 40kHz for 30min to obtain the modified extract;

[0059] The preparation of nano-alloy particles includes the following steps:

[0060] S21. Add 50g of alloy metal powder (composed of manganese, zinc, iron and bismuth in equal parts by mass) and 1g of stearic acid to a high-energy ball mill to obtain mixed alloy particles;

[0061] S22. Evacuate the ball mill and introduce argon gas. Ball mill in a cycle mode of 30 min ball milling followed by 15 min pause cooling (ball-to-material mass ratio of 15:1, ball mill speed of 350 rpm) for 24 h to obtain nano-alloy particles.

[0062] The preparation of modified surface modifiers includes the following steps:

[0063] S31. Dissolve 1g of γ-(methacryloyloxy)propyltrimethoxysilane and 0.5g of hexadecyltrimethoxysilane in 8ml of anhydrous ethanol and stir at 350r / min for 10min.

[0064] S32. Add 0.8 ml of deionized water to the mixture obtained in step S31, and adjust the pH of the solution to 5 using acetic acid. Stir at 350 r / min for 30 min to obtain the modified surface modifier.

[0065] S1. Pretreatment of oil-based drill cuttings: The liquid phase (carbon exists in the form of alkanes and cycloalkanes) and the solid phase (carbon mainly consists of base oil adsorbed on the surface of drill cutting particles and organic matter from the formation) of oil-based drill cuttings (composed of base oil, rock particles and organic and inorganic additives) are separated by centrifugation (3000 rpm, 20 min). The liquid phase is purified by distillation and reused for drilling fluid base oil. Low molecular weight hydrocarbons in the solid phase are removed by extraction modification liquid. The extraction modification liquid and the solid phase are then soaked in a 3:1 ratio for 2 h. After filtration, a high carbon content solid phase is obtained.

[0066] S2. Catalytic pyrolysis: 2g of nano-alloy particles and 30g of carbon-containing solid phase are mixed in a tube furnace, nitrogen gas is introduced, the temperature is raised to 1200℃ and held for 120min to generate graphene.

[0067] S3. Graphene surface modification: Graphene was washed with a 25% hydrochloric acid solution and then dispersed in anhydrous ethanol (1:100 ratio). It was ultrasonically treated at a frequency of 40kHz for 30min until it was uniformly suspended. 10g of modified surface modifier was slowly added and the mixture was magnetically stirred at 400r / min in a 62℃ water bath for 5h. After centrifugation, washing and drying, modified graphene was obtained.

[0068] S4. Drilling fluid preparation: Add 0.5% modified graphene to oil-based drilling fluid to form graphene-enhanced drilling fluid;

[0069] S5. Recycling: During the drilling process, the used drilling fluid containing drill cuttings is recovered and steps S1-S4 are repeated to form a recycling system.

[0070] Example 3

[0071] A method for preparing graphene by catalytic cracking of oil-based drill cuttings:

[0072] Before preparing graphene from oil-based drill cuttings through catalytic cracking, the following steps are taken: preparation of extraction modification solution, nano-alloy particles, and surface modifiers.

[0073] The preparation of the extraction modified solution includes the following steps:

[0074] S11. Add 3.5g pyridine and 1.5g tributyl phosphate to 85g n-hexane, and stir at 320r / min for 11min in a water bath at 39℃ to obtain a preliminary extract.

[0075] S12. Add 1.2g sodium dodecylbenzenesulfonate, 1.3g iron acetylacetone and 1.6g oleic acid to the preliminary extract, and ultrasonically disperse at a frequency of 40kHz for 22min to obtain the modified extract;

[0076] The preparation of nano-alloy particles includes the following steps:

[0077] S21. Add 46g of alloy metal powder (composed of nickel, manganese, zinc and iron in equal parts by mass) and 0.9g of stearic acid to a high-energy ball mill to obtain mixed alloy particles;

[0078] S22. Evacuate the ball mill and introduce argon gas. Ball mill in a cycle mode of 26 min ball milling followed by 11 min pause cooling (ball-to-material mass ratio of 15:1, ball mill speed of 320 rpm) for 21 h to obtain nano-alloy particles.

[0079] The preparation of modified surface modifiers includes the following steps:

[0080] S31. Dissolve 0.6g of γ-(methacryloyloxy)propyltrimethoxysilane and 0.35g of hexadecyltrimethoxysilane in 7.5ml of anhydrous ethanol and stir at 320r / min for 6min.

[0081] S32. Add 0.6 ml of deionized water to the mixture obtained in step S31, and adjust the pH of the solution to 4.5 using acetic acid. Stir at 320 r / min for 22 min to obtain the modified surface modifier.

[0082] S1. Oil-based drill cuttings pretreatment: The liquid phase (carbon exists in the form of alkanes and cycloalkanes) and solid phase (carbon mainly consists of base oil adsorbed on the surface of drill cuttings and organic matter from the formation) of oil-based drill cuttings (composed of base oil, rock particles and organic and inorganic additives) are separated by centrifugation (2600 rpm, 16 min). The liquid phase is purified by distillation and reused for drilling fluid base oil. Low molecular weight hydrocarbons in the solid phase are removed by extraction modification liquid. The extraction modification liquid and the solid phase are then soaked in a 3:1 ratio for 1.5 h. After filtration, a high carbon content solid phase is obtained.

[0083] S2. Catalytic pyrolysis: 1.2g of nano-alloy particles and 15g of carbon-containing solid phase are mixed in a tube furnace, nitrogen gas is introduced, the temperature is raised to 900℃ and held for 50min to generate graphene.

[0084] S3. Graphene surface modification: Graphene was washed with 21% hydrochloric acid solution and then dispersed in anhydrous ethanol (1:100 ratio) and sonicated at 40kHz for 26 min until uniform suspension. 8.5g of modified surface modifier was slowly added and the mixture was magnetically stirred at 320r / min in a 60℃ water bath for 4.5h. Modified graphene was obtained by centrifugation, washing and drying.

[0085] S4. Drilling fluid preparation: Add 0.2% modified graphene to oil-based drilling fluid to form graphene-enhanced drilling fluid;

[0086] S5. Recycling: During the drilling process, the used drilling fluid containing drill cuttings is recovered and steps S1-S4 are repeated to form a recycling system.

[0087] Example 4

[0088] A method for preparing graphene by catalytic cracking of oil-based drill cuttings:

[0089] Before preparing graphene from oil-based drill cuttings through catalytic cracking, the following steps are taken: preparation of extraction modification solution, nano-alloy particles, and surface modifiers.

[0090] The preparation of the extraction modified solution includes the following steps:

[0091] S11. Add 4g of pyridine and 2g of tributyl phosphate to 92g of n-hexane, and stir at 370r / min for 14min in a water bath at 39℃ to obtain a preliminary extract.

[0092] S12. Add 1.5g sodium dodecylbenzenesulfonate, 1.4g iron acetylacetone and 1.8g oleic acid to the preliminary extract, and ultrasonically disperse at a frequency of 40kHz for 28min to obtain the modified extract;

[0093] The preparation of nano-alloy particles includes the following steps:

[0094] S21. Add 48g of alloy metal powder (composed of cobalt, manganese, iron, tin and bismuth in equal parts by mass) and 0.9g of stearic acid to a high-energy ball mill to obtain mixed alloy particles;

[0095] S22. Evacuate the ball mill and introduce argon gas. Ball mill in a cycle mode of 28 min ball milling followed by 14 min pause cooling (ball-to-material mass ratio of 15:1, ball mill speed of 340 rpm) for 23 h to obtain nano-alloy particles.

[0096] The preparation of modified surface modifiers includes the following steps:

[0097] S31. Dissolve 0.8g of γ-(methacryloyloxy)propyltrimethoxysilane and 0.45g of hexadecyltrimethoxysilane in 7.5ml of anhydrous ethanol and stir at 340r / min for 8min.

[0098] S32. Add 0.7 ml of deionized water to the mixture obtained in step S31, and adjust the pH of the solution to 4.5 using acetic acid. Stir at 340 r / min for 28 min to obtain the modified surface modifier.

[0099] S1. Pretreatment of oil-based drill cuttings: The liquid phase (carbon exists in the form of alkanes and cycloalkanes) and the solid phase (carbon mainly consists of base oil adsorbed on the surface of drill cutting particles and organic matter from the formation) of oil-based drill cuttings (composed of base oil, rock particles and organic and inorganic additives) are separated by centrifugation (2800 rpm, 18 min). The liquid phase is purified by distillation and reused for drilling fluid base oil. Low molecular weight hydrocarbons in the solid phase are removed by extraction modification liquid. The extraction modification liquid and the solid phase are then soaked in a 3:1 ratio for 1.5 h. After filtration, a high carbon content solid phase is obtained.

[0100] S2. Catalytic pyrolysis: 1.8g of nano-alloy particles and 25g of carbon-containing solid phase are mixed in a tube furnace, nitrogen gas is introduced, the temperature is raised to 1100℃ and held for 80min to generate graphene.

[0101] S3. Graphene surface modification: Graphene was washed with 24% hydrochloric acid solution and then dispersed in anhydrous ethanol (1:100 ratio) and sonicated at 40kHz for 28min until uniform suspension. 9.5g of modified surface modifier was slowly added and the mixture was magnetically stirred at 370r / min in a 61℃ water bath for 4.5h. Modified graphene was obtained by centrifugation, washing and drying.

[0102] S4. Drilling fluid preparation: Add 0.4% modified graphene to oil-based drilling fluid to form graphene-enhanced drilling fluid;

[0103] S5. Recycling: During the drilling process, the used drilling fluid containing drill cuttings is recovered and steps S1-S4 are repeated to form a recycling system.

[0104] Comparative Example 1

[0105] The only difference between Comparative Example 1 and Example 1 is that the nano-alloy particles are replaced with traditional Fe nanoparticles in this comparative example. The remaining steps are exactly the same in Comparative Example 1 and Example 1.

[0106] Comparative Example 2

[0107] The only difference between Comparative Example 2 and Example 1 is that no modified surface modifier was added in this comparative example; the other steps are exactly the same in Comparative Example 2 and Example 1.

[0108] Performance testing:

[0109] The total mass of the nano-alloy particles and carbon-containing solid phase in step S2 of Examples 1-4 and Comparative Examples 1-2, and the mass of the modified graphene obtained in step S3 were weighed respectively to conduct a yield test of the modified graphene. The yields are shown in Table 1 below:

[0110] Table 1

[0111]

[0112] As shown in Table 1, the yields of the embodiments of the present invention are generally higher than those of the modified graphene in the comparative examples. This fully demonstrates that the synergistic effect of the nano-alloy particles and the modified surface modifier in the present invention more effectively improves the graphene yield and solves the problem of low yield and poor structure caused by the easy carbon deposition and deactivation of traditional Fe nanoparticles.

[0113] The lubrication coefficient and HTTP filtration loss of the graphene-enhanced drilling fluids obtained in Examples 1-4 and Comparative Examples 1-2 were tested using an extreme pressure lubrication tester (ASTM D5183) and an HTTP filtration loss meter (API RP 13B-2). The results are shown in Table 2 below.

[0114] Table 2

[0115]

[0116] Based on the data in Table 2, the graphene-reinforced drilling fluids obtained from conventional Fe nanoparticles and without modified surface agents in Comparative Examples 1 and 2 are inferior to the graphene-reinforced drilling fluid obtained in the examples in terms of lubricity and filtration efficiency. This invention effectively improves the lubricity and filtration efficiency of drilling fluids while enabling their recycling, verifying the catalytic advantages of high-entropy alloys and the necessity of surface modification.

[0117] Appendix Figure 5 This is the SEM image of the modified graphene obtained in Example 1 of this invention. The image shows that the modified graphene exhibits a typical two-dimensional sheet structure with a small number of layers and high transparency, indicating successful and efficient graphitization of the carbon source and a relatively complete structure. The sheet edges are clear, without obvious curling or breakage, indicating that the high-entropy alloy catalyst effectively promoted the ordered arrangement of carbon atoms during the pyrolysis process, avoiding the formation of amorphous carbon. After surface modification, no obvious agglomeration or accumulation was observed on the graphene sheet surface, indicating that the modified surface modifier was successfully modified, improving its dispersibility and stability in the organic phase.

[0118] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing graphene by catalytic cracking of oil-based drill cuttings, characterized in that, The preparation steps include the following: S1. Pretreatment of oil-based drill cuttings: The liquid and solid phases in the oil-based drill cuttings are separated by centrifugation. The liquid phase is purified by distillation and reused in drilling fluid-based oil. Extraction is carried out using an extraction-modifying liquid, and the resulting solid is then soaked in the extraction-modifying liquid and filtered to obtain a high-carbon solid phase. S2. Catalytic cracking: By mass, 1-2 parts of nano-alloy particles are mixed with 10-30 parts of carbon-containing solid phase in a tube furnace, nitrogen is introduced, the temperature is raised to 800-1200℃ and held for 30-120 min to generate graphene. S3. Graphene surface modification: Wash graphene with a 20-25% hydrochloric acid solution, then disperse it in anhydrous ethanol and sonicate for 25-30 min until uniformly suspended. Slowly add 8-10 parts of modified surface modifier, and react with magnetic stirring at 300-400 r / min in a water bath at 58-62℃ for 4-5 h. After centrifugation, washing and drying, the modified graphene is obtained. The preparation of the extraction-modified solution includes the following steps: S11. By weight, add 3-5 parts of pyridine and 1-3 parts of tributyl phosphate to 80-100 parts of n-hexane, and stir for 10-15 minutes at a speed of 300-400 r / min in a water bath at 38-40℃ to obtain a preliminary extract. S12. Add 1-2 parts sodium dodecylbenzenesulfonate, 1.2-1.5 parts ferric acetylacetone and 1.5-2 parts oleic acid to the preliminary extract, and ultrasonically disperse at a frequency of 40 kHz for 20-30 min to obtain the modified extract.

2. The method for preparing graphene by catalytic cracking of oil-based drill cuttings according to claim 1, characterized in that, The preparation of the nano-alloy particles includes the following steps: S21. By weight, 45-50 parts of alloy metal powder and 0.8-1 parts of stearic acid are added to a high-energy ball mill to obtain mixed alloy particles; S22. Evacuate the ball mill and introduce argon gas. Ball mill for 20-24 hours in a cycle mode of 25-30 min ball milling followed by 10-15 min pause cooling to obtain nano-alloy particles.

3. The method for preparing graphene by catalytic cracking of oil-based drill cuttings according to claim 1, characterized in that, The preparation of the modified surface modifier includes the following steps: S31. By weight, dissolve 0.5-1 parts of γ-(methacryloyloxy)propyltrimethoxysilane and 0.3-0.5 parts of hexadecyltrimethoxysilane in 7-8 parts of anhydrous ethanol, and stir at 300-350 r / min for 5-10 min. S32. Add 0.5-0.8 parts of deionized water to the mixture obtained in step S31, and adjust the pH of the solution to 4-5 using acetic acid. Stir at 300-350 r / min for 20-30 min to obtain the modified surface modifier.

4. The method for preparing graphene by catalytic cracking of oil-based drill cuttings according to claim 1, characterized in that, In step S1, the centrifugation speed is 2500-3000 rpm and the time is 15-20 min.

5. The method for preparing graphene by catalytic cracking of oil-based drill cuttings according to claim 1, characterized in that, In step S3, the mass ratio of graphene to anhydrous ethanol is 1:

100.

6. The method for preparing graphene by catalytic cracking of oil-based drill cuttings according to claim 2, characterized in that, The alloy metal powder is composed of two or more of the following: copper, nickel, cobalt, manganese, zinc, iron, tin, and bismuth.

7. The method for preparing graphene by catalytic cracking of oil-based drill cuttings according to claim 2, characterized in that, In step S22, the ball-to-material mass ratio in the ball mill is 15:1, and the ball mill speed is 300-350 rpm.

8. The method for preparing graphene by catalytic cracking of oil-based drill cuttings according to claim 1, characterized in that, In step S1, the mass ratio of the extraction modified liquid to the solid is 3:1, and the soaking time is 1-2 hours.

9. The method for preparing graphene by catalytic cracking of oil-based drill cuttings according to claim 1, characterized in that, The frequency of the ultrasonic treatment in step S3 is 40 kHz.

10. The application of the modified graphene prepared by the method according to any one of claims 1-9 in drilling fluid recycling, characterized in that, The specific application involves adding modified graphene at 0.1-0.5% to oil-based drilling fluid to form graphene-enhanced drilling fluid. The oil-based drill cuttings formed after the graphene-enhanced drilling fluid is put into use are then recycled to prepare modified graphene for reuse, forming a cycle.

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