A lubricant with a modified silicon carbide particle structure coated with resin material for drilling fluid, and its preparation method and application

Abstract

The present invention provides a lubricant for drilling fluid with a resin-coated modified silicon carbide particle structure, as well as its preparation method and application, belonging to the technical field of lubricants for oilfield drilling fluids. The preparation method of the lubricant of the present invention comprises the following steps: adding pretreated nano-SiC particles, hydroxyethyl acrylate, lauryl acrylate, and a silane coupling agent to a base oil, then adding a chain transfer agent, stirring, adding an initiator, and reacting; after the reaction is completed, filtering, washing, and drying to obtain modified nano-SiC particles; adding the modified nano-SiC particles to a fluorocarbon resin solution, heating to react, drying, and grinding to obtain. The present invention has developed a new high-efficiency lubricant material for drilling fluid. The lubricant material of the present invention can not only significantly reduce the flow resistance of the drilling fluid and the friction coefficient of the filter cake, slowing down the wear of the drill tool, but also has excellent wear and corrosion resistance, which can effectively improve drilling efficiency and extend the service life of the drill bit.

Description

Technical Field

[0001] The invention relates to a lubricant with a resin material-coated modified silicon carbide particle structure for drilling fluid, a preparation method and application thereof, and belongs to the technical field of lubricants for oilfield drilling fluid. Background Art

[0002] During drilling, three main types of friction occur: direct dry friction between the drill string and the wellbore wall without any medium; boundary friction caused by the boundary film effect between the drill string and the wellbore wall; and flow friction caused by the circulation of the drilling fluid. To reduce friction, a variety of drilling fluid lubricants have been developed. Commonly used drilling fluid lubricants mainly include liquid lubricants and solid lubricants. Commonly used liquid lubricants include mineral oil lubricants, vegetable oil lubricants, polymerized alcohol lubricants, and sulfonated tall oil lubricants. Solid lubricants mainly include modified graphite, carbon spheres, soft metals, alkaline earth metal fluorides, and soft oxides.

[0003] However, with the increasing number of complex well structures such as horizontal wells, extended reach wells, and cluster wells in drilling projects, the drawbacks of existing conventional drilling fluid lubricants in extremely complex environments have become increasingly prominent. Chinese patent document CN109439296A discloses a drilling fluid lubricant, its preparation method, and its application. The lubricant is composed of nanographite, fatty acid esters, surfactants, phosphate esters, and water. However, this lubricant can only achieve uniform lubrication at all locations, exerting the same effect on high-friction and low-friction areas, and cannot adapt to different formations and drilling conditions. U.S. patent document US7250390B2 discloses a high-efficiency drilling fluid lubricant prepared from sorbitol and ricinoleic acid. This lubricant solves the foaming problem of ester lubricants, improving the rheological properties of the drilling fluid and reducing fluid loss. European patent document EP2036963 (A1) discloses an oligoglycerol fatty acid ester obtained from an acid component, preferably a fatty acid compound (I), a dicarboxylic acid, a dimer, an oligomer, or a hydroxy fatty acid, and its polyol component, which is an oligoglycerol or oligoglycerol alkoxy ester, can be used as a lubricating additive in oil-based drilling fluids, but fatty acid ester lubricants are prone to failure in high temperature and high salt environments.

[0004] Currently, drilling fluid lubricants are increasingly unable to meet the lubricant requirements of complex wells, severely impacting drilling speeds and accelerating drill bit wear. As well depths continue to increase, complex accidents such as high friction and torque during drilling present new challenges for safe and efficient deep-layer drilling. Therefore, to address the challenges of torque resistance and excessive drill tool wear faced in deep and ultra-deep oil and gas exploration and development, developing new, highly efficient drilling fluid lubricants is a key approach to addressing these challenges. This present invention addresses this issue. Summary of the Invention

[0005] To address the shortcomings of existing technologies, particularly the challenges faced by complex well structures such as extended-reach horizontal wells in deep, ultra-deep, and offshore oil and gas drilling and production, such as high friction and torque, severe drill tool wear, and a high risk of sticking, the present invention provides a lubricant for drilling fluids comprising a resin-coated modified silicon carbide particle structure, as well as its preparation method and application. The present invention has developed a new, highly efficient lubricant material for drilling fluids. This lubricant material not only significantly reduces the flow resistance of the drilling fluid and the filter cake friction coefficient, mitigating drill tool wear, but also exhibits excellent wear and corrosion resistance, effectively improving drilling efficiency and extending the service life of the drill bit.

[0006] The technical solutions of the present invention are as follows:

[0007] A method for preparing a lubricant having a modified silicon carbide particle structure coated with a resin material for drilling fluid comprises the following steps:

[0008] (1) adding nano-SiC particles to a mixed solvent of ethyl acetate and butyl acetate, stirring evenly, and then performing ultrasonic dispersion to obtain a nano-SiC dispersion; filtering and drying to obtain pretreated nano-SiC particles;

[0009] (2) adding the pretreated nano-SiC particles obtained in step (1), hydroxyethyl acrylate, lauryl acrylate and a silane coupling agent to a base oil, then adding a chain transfer agent, stirring, and then adding an initiator to carry out a reaction; after the reaction is completed, filtering, washing and drying to obtain modified nano-SiC particles;

[0010] (3) Adding the modified nano-SiC particles obtained in step (2) to a fluorocarbon resin solution, heating to react, drying, and grinding to obtain a lubricant with a modified silicon carbide particle structure coated with a resin material for drilling fluid.

[0011] Preferably, according to the present invention, the mass ratio of ethyl acetate to butyl acetate in the mixed solvent in step (1) is 1:1-2; and the mass ratio of the mixed solvent to the nano-SiC particles is 10-40:1.

[0012] According to the preferred embodiment of the present invention, the stirring speed in step (1) is 200-300 r / min; the ultrasonic dispersion time is 6-12 h; and the drying is performed at 60-75° C. to a constant weight.

[0013] According to the preferred embodiment of the present invention, the mass ratio of the pretreated nano-SiC particles, hydroxyethyl acrylate and lauryl acrylate in step (2) is 1:6-20:1-4.

[0014] According to the present invention, preferably, the silane coupling agent in step (2) is one or more of vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, and vinyltri(β-methoxyethoxy)silane; and the mass ratio of the silane coupling agent to the pretreated nano-SiC particles is 1:4-20.

[0015] According to the present invention, the base oil in step (2) is preferably white oil, and more preferably 5 ＃ White oil or 7 ＃ White oil; the mass ratio of the base oil to the pretreated nano-SiC particles is 20-100:1.

[0016] According to the preferred embodiment of the present invention, the chain transfer agent in step (2) is one of dodecyl mercaptan, trichloroethylene, and 2-mercaptopropanol; and the mass ratio of the chain transfer agent to the pretreated nano-SiC particles is 1-5:100.

[0017] According to the preferred embodiment of the present invention, the stirring temperature in step (2) is 80-120°C, more preferably 90°C, the stirring time is 50-70min, and the stirring speed is 400-500r / min; the stirring is carried out under a nitrogen atmosphere.

[0018] Preferably, according to the present invention, the initiator in step (2) is one of azobisisobutyronitrile and potassium persulfate; and the mass ratio of the initiator to the pretreated nano-SiC particles is 1-5:100.

[0019] Preferably, according to the present invention, the reaction temperature in step (2) is 70-80° C., and the reaction time is 6-8 h; the reaction is carried out under a nitrogen atmosphere, and the stirring rate during the reaction is 400-500 r / min.

[0020] According to the preferred embodiment of the present invention, the washing in step (2) is performed by washing with anhydrous ethanol for 3-5 times; and the drying is performed at 65-85° C. for 4-6 hours.

[0021] Preferably, according to the present invention, the fluorocarbon resin solution in step (3) is obtained by adding fluorocarbon resin to dioctyl azelaic acid and ultrasonically treating the mixture for 5-7 hours; the mass ratio of the fluorocarbon resin to dioctyl azelaic acid is 1:1-20; there are no specific requirements for the fluorocarbon resin, and ordinary commercially available products can be used, such as RF-301 solvent-based two-component fluorocarbon resin or RF-302 solvent-based two-component fluorocarbon resin produced by Fuxin Ruifeng Fluorochemical Co., Ltd.

[0022] According to the preferred embodiment of the present invention, the mass ratio of the modified nano-SiC particles to the fluorocarbon resin solution in step (3) is 1:40-120.

[0023] According to the preferred embodiment of the present invention, the heating in step (3) is heating to 320-400°C, more preferably 360°C; the heating reaction time is 6-8h; and the drying is drying at 60-70°C for 18-30h.

[0024] The present invention also provides a lubricant with a resin material-coated modified silicon carbide particle structure for drilling fluid, which is prepared by the above-mentioned preparation method.

[0025] According to the present invention, the lubricant with a modified silicon carbide particle structure coated with a resin material for drilling fluid is used in drilling fluid as a lubricant in the drilling process to achieve the drilling goal of reducing drag and increasing speed. Preferably, the specific application is as follows: at the beginning of the drilling operation, a lubricant with a modified silicon carbide particle structure coated with a resin material for drilling fluid is added to the drilling fluid at a mass concentration of 0.2-1.2wt%.

[0026] The technical features and beneficial effects of the present invention are as follows:

[0027] 1. This invention addresses the challenges of high friction and torque, severe drill tool wear, and other challenges faced by complex well structures such as long horizontal wells in deep and ultra-deep oil and gas production. It provides a lubricant for use in drilling fluids with a coated structure. This lubricant significantly reduces the lubrication coefficient with just a small addition. The lubricant can effectively reduce friction and torque during drilling, alleviate drill bit wear, and improve drilling efficiency.

[0028] 2. The lubricant of the present invention utilizes modified nano-silicon carbide particles as its core, coated with a fluorocarbon resin material. This forms a dense fluorocarbon resin film on the surface of the nano-silicon carbide particles, significantly improving the material's lubrication and wear resistance. This allows for long-term performance and prevents material failure even with minor wear. Furthermore, the fluorocarbon resin, with its high corrosion resistance, acts as a shell coating, protecting the lubricant from formation fluids, ensuring its effectiveness. Its non-adhesive properties also significantly improve the yield of the material, making it less susceptible to adhesion.

[0029] 3. The lubricant of the present invention uses nano-sized silicon carbide particles obtained by modifying silicon carbide particles with hydroxyethyl acrylate and dodecyl acrylate as the core. Hydroxyethyl acrylate (HEA) is a polar acrylate, and its terminal hydroxyl groups can enhance the adsorption capacity of the polymer on the surface of the drill tool and can also form a polymer film on the metal surface. Dodecyl acrylate is a long-chain acrylate that can expand the adsorption area of the polymer on the solid surface and enhance the strength of the lubricating film. In the high friction resistance area of the lubricant material of the present invention, after the outer fluorocarbon resin material is damaged, the modified silicon carbide material inside is exposed and adsorbed on the surface of the drill tool, thereby improving the efficiency of the lubricant. The fluorocarbon resin material is used as the lubricant shell, and the fluorocarbon resin-coated modified silicon carbide particles can withstand temperatures of 220°C. Lubricants obtained by resin-coating unmodified silicon carbide particles, or uncoated modified silicon carbide particles, have poorer performance.

[0030] 4. In the preparation method of the present invention, the mass ratio of fluorocarbon resin to nano-SiC particles must be appropriate. If it is not appropriate, the coating effect will be poor, thereby reducing the performance of the lubricant material. The preparation method of the present invention as a whole requires the combined effect of each step and condition to achieve the excellent results of the present invention.

[0031] 5. The lubricant preparation method of the present invention is simple, the reaction conditions are relatively mild, and it has excellent adaptability to extremely complex well conditions. It has the prospect of large-scale industrial production and shows great potential for the exploitation of oil and gas in deep, ultra-deep, and deep-water marine complex structure wells. DETAILED DESCRIPTION

[0032] The present invention will be further described below with reference to specific embodiments, but is not limited thereto.

[0033] Meanwhile, the experimental methods described in the following examples, unless otherwise specified, are conventional methods; the reagents, materials and equipment, unless otherwise specified, can be obtained from commercial channels.

[0034] The fluorocarbon resin used in the examples is RF-301 solvent-based two-component fluorocarbon resin produced by Fuxin Ruifeng Fluorochemical Co., Ltd.

[0035] Example 1

[0036] A method for preparing a lubricant having a modified silicon carbide particle structure coated with a resin material for drilling fluid comprises the following steps:

[0037] (1) Pretreatment of nano-SiC particles

[0038] 5 g of nano-SiC particles (particle size of 40-50 nm) were added to 100 g of a mixed solvent (the mixed solvent was obtained by mixing ethyl acetate and butyl acetate in a mass ratio of 1:1), first stirred and mixed uniformly at a stirring speed of 300 r / min, and then ultrasonically dispersed for 12 hours to obtain a nano-SiC dispersion; then filtered and dried at 75°C to constant weight to obtain pretreated nano-SiC particles.

[0039] (2) Modification of nano-SiC particles

[0040] Weigh 5g of pretreated nano-SiC particles, 50g of hydroxyethyl acrylate, 10g of lauryl acrylate and 1g of silane coupling agent (a combination of vinyl trimethoxysilane and vinyl triethoxysilane, the mass ratio of the two is 1:1), mix them evenly and dissolve them in 300g of base oil (7 ＃ white oil); then add 0.2g of chain transfer agent dodecyl mercaptan, and bubble with nitrogen; under nitrogen atmosphere, stir at 90°C and a stirring speed of 500r / min for 60min; then add 0.2g of azobisisobutyronitrile, react at 75°C for 8h, and stir at a speed of 500r / min during the reaction; after the reaction is completed, cool naturally to room temperature; filter, wash the reaction product with anhydrous ethanol three times, and dry at 65°C for 4h to obtain modified nano-SiC particles.

[0041] (3) Coating of modified nano-SiC particles

[0042] Fluorocarbon resin is added to dioctyl azelate and ultrasonically treated for 6 hours to form a uniform fluorocarbon resin solution, wherein the mass ratio of fluorocarbon resin to dioctyl azelate is 1:10; 1 part by weight of modified nano-SiC particles is placed in a beaker, and 80 parts by weight of fluorocarbon resin solution is added thereto. The mixture is maintained at 360°C on an electric furnace and heated for 6 hours. The mixture is stirred with a stirrer to gradually volatilize the dioctyl azelate and gradually deposit the fluorocarbon resin on the surface of the modified nano-SiC particles; the heated and stirred mixture is dried at 65°C for 24 hours; and after screening and grinding, a lubricant with a modified silicon carbide particle structure coated with a resin material for drilling fluid is obtained.

[0043] Example 2

[0044] A method for preparing a lubricant having a modified silicon carbide particle structure coated with a resin material for drilling fluid is as described in Example 1, except that the amount of fluorocarbon resin solution added in step (3) is 40 parts by weight.

[0045] Example 3

[0046] A method for preparing a lubricant having a modified silicon carbide particle structure coated with a resin material for drilling fluid is as described in Example 1, except that the amount of fluorocarbon resin solution added in step (3) is 120 parts.

[0047] Example 4

[0048] A method for preparing a lubricant having a modified silicon carbide particle structure coated with a resin material for drilling fluid is as described in Example 1, except that the initiator is replaced by potassium persulfate in step (2).

[0049] Comparative Example 1

[0050] A method for preparing a lubricant for drilling fluid is as described in steps (1)-(2) of Example 1, without performing the coating in step (3).

[0051] Comparative Example 2

[0052] A method for preparing a lubricant for drilling fluid is as described in Example 1, except that in step (2), 5 g of pretreated nano-SiC particles, 20 g of hydroxyethyl acrylate, 5 g of lauryl acrylate and 0.5 g of silane coupling agent are used.

[0053] Test example

[0054] Lubrication performance is the primary factor in evaluating whether a drilling fluid lubricant meets the requirements for use. Based on the SY / T 6094-1994 "Evaluation Procedure for Lubricants Used in Drilling Fluids" and GB / T 16783.1-2006 "Field Testing of Drilling Fluids in the Petroleum and Natural Gas Industry," an extreme pressure lubrication tester is used to measure the lubrication performance of the base slurry after adding lubricants at different concentrations. The lower the lubrication coefficient or the greater the rate of lubrication coefficient reduction, the better the lubricant's friction and drag reduction performance. The drilling fluid lubrication coefficient formula is as follows:

[0055]

[0056] Where: R-lubrication coefficient reduction rate, %; η0-lubrication coefficient without adding lubricant; η1-lubrication coefficient with adding lubricant.

[0057] 5% base slurry formula: 500 parts of water + 25 parts of bentonite for drilling fluid + 1 part of anhydrous sodium carbonate, hydrated for 24 hours.

[0058] Different weight percentages of lubricants prepared in the Examples or Comparative Examples were added to 500 mL of base slurry. The mixture was stirred at 8000 rpm for 10 minutes, then transferred to a high-temperature roller heating furnace and hot-rolled at 220°C for 16 hours. The lubricity coefficients of the slurries before and after aging were measured using an EP-1 extreme pressure lubrication instrument. The results are shown in Table 1.

[0059] Table 1 Lubrication coefficient after adding lubricants prepared in Example 1 in different proportions

[0060]

[0061] Table 2 Lubrication coefficient after adding lubricants prepared in Example 2 in different proportions

[0062]

[0063] Table 3 Lubrication coefficient after adding lubricants prepared in Example 3 in different proportions

[0064]

[0065] Table 4 Lubrication coefficient after adding lubricants prepared in Example 4 in different proportions

[0066]

[0067] Tables 1-4 show that the lubricity coefficients of the materials prepared in Examples of the present invention show little change after aging at 220°C, demonstrating that the lubricants maintain excellent lubricity even after aging at 220°C. However, the addition of varying amounts of fluorocarbon resin in Examples 1-3 impacts the coating effect and coating thickness, thus affecting the rate of lubricity reduction. Overall, the lubricity coefficient in Example 4 shows minimal change.

[0068] Table 5 Lubrication coefficient after adding lubricants prepared in Comparative Example 1 in different proportions

[0069]

[0070] As can be seen from Table 5, the uncoated modified nano-SiC particles in Comparative Example 1 can reduce the lubrication coefficient to a certain extent, and the lubrication coefficient reduction rate is between 20% and 45%; however, the high temperature of 220°C has little effect on it, and the lubrication coefficient fluctuates slightly after high-temperature aging. However, overall, the uncoated modified SiC material can still withstand a temperature of 220°C, but the lubrication coefficient reduction rate is much lower than that of the coated material.

[0071] Table 6 Lubrication coefficient after adding lubricants prepared in Comparative Example 2 in different proportions

[0072]

[0073] As can be seen from Table 6, in Comparative Example 2, the mass ratio of nano-SiC is too large, making it difficult to achieve uniform coating of the pretreated nano-SiC particles with the fluorocarbon resin, resulting in reduced lubrication performance and a decrease in the lubrication coefficient reduction rate.

[0074] Table 7 Lubrication coefficient after adding different proportions of lubricant (RY-828)

[0075]

[0076] Table 8 Lubrication coefficient after adding different proportions of lubricant (vegetable oil RH-1)

[0077]

[0078] It can be seen from Table 7-8 that lubricant RY-828 and vegetable oil RH-1 have a higher lubricity coefficient reduction rate before aging, but their temperature resistance is poor. After aging, the lubricity coefficient drops significantly.

[0079] In summary, it can be seen that the lubricant of the present invention can effectively reduce the friction and torque during the drilling process of the drill tool, reduce drill bit wear, improve drilling efficiency, and effectively solve the problems of large friction and torque, severe drill tool wear, etc. faced by complex structure wells such as long horizontal wells in deep and ultra-deep oil and gas production. It has the advantage of significantly reducing the lubrication coefficient by adding a small amount.

Claims

1. A method for preparing a lubricant having a modified silicon carbide particle structure coated with a resin material for drilling fluid, characterized in that: The steps are as follows: (1) adding nano-SiC particles to a mixed solvent of ethyl acetate and butyl acetate, stirring evenly, and then performing ultrasonic dispersion to obtain a nano-SiC dispersion; filtering and drying to obtain pretreated nano-SiC particles; the mass ratio of ethyl acetate to butyl acetate in the mixed solvent is 1:1-2; the mass ratio of the mixed solvent to the nano-SiC particles is 10-40:1; (2) adding the pretreated nano-SiC particles obtained in step (1), hydroxyethyl acrylate, lauryl acrylate and silane coupling agent to base oil, then adding a chain transfer agent, stirring, adding an initiator and reacting; after the reaction is completed, filtering, washing and drying to obtain modified nano-SiC particles; the mass ratio of the pretreated nano-SiC particles, hydroxyethyl acrylate and lauryl acrylate is 1:6-20:1-4; the silane coupling agent is vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropyl One or more of trimethoxysilane, vinyl tri(β-methoxyethoxy)silane, the mass ratio of the silane coupling agent to the pretreated nano-SiC particles is 1:4-20; the base oil is white oil; the chain transfer agent is one of dodecyl mercaptan, trichloroethylene, and 2-mercaptopropanol, and the mass ratio of the chain transfer agent to the pretreated nano-SiC particles is 1-5:100; the initiator is one of azobisisobutyronitrile and potassium persulfate; the mass ratio of the initiator to the pretreated nano-SiC particles is 1-5:100; the reaction temperature is 70-80°C, and the reaction time is 6-8h; (3) adding the modified nano-SiC particles obtained in step (2) to a fluorocarbon resin solution, heating to react, drying, and grinding to obtain a lubricant having a modified silicon carbide particle structure coated with a resin material for drilling fluid; The fluorocarbon resin solution is obtained by adding fluorocarbon resin to dioctyl azelaic acid and performing ultrasonic treatment. The mass ratio of the fluorocarbon resin to the dioctyl azelaic acid is 1:1-20, and the mass ratio of the modified nano-SiC to the fluorocarbon resin solution is 1:40-120. The heating is performed to 320-400°C. The heating reaction time is 6-8 hours. The fluorocarbon resin is RF-301 solvent-based two-component fluorocarbon resin or RF-302 solvent-based two-component fluorocarbon resin produced by Fuxin Ruifeng Fluorochemical Co., Ltd.

2. The method for preparing a lubricant having a modified silicon carbide particle structure coated with a resin material for drilling fluid according to claim 1, characterized in that: The stirring speed in step (1) is 200-300 r / min; the ultrasonic dispersion time is 6-12 h; and the drying is performed at 60-75° C. to a constant weight.

3. The method for preparing a lubricant having a modified silicon carbide particle structure coated with a resin material for drilling fluid according to claim 1, characterized in that: The white oil in step (2) is 5 ＃ White oil or 7 ＃ White oil; the mass ratio of the base oil to the pretreated nano-SiC particles is 20-100:

1.

4. The method for preparing a lubricant having a modified silicon carbide particle structure coated with a resin material for drilling fluid according to claim 1, characterized in that: The stirring temperature in step (2) is 80-120° C., the stirring time is 50-70 min, and the stirring speed is 400-500 r / min; the stirring is carried out under a nitrogen atmosphere.

5. The method for preparing a lubricant having a modified silicon carbide particle structure coated with a resin material for drilling fluid according to claim 1, characterized in that: The reaction in step (2) is carried out under a nitrogen atmosphere, and the stirring rate during the reaction is 400-500 r / min; The washing step comprises washing the mixture with anhydrous ethanol for 3-5 times; and the drying step comprises drying the mixture at 65-85° C. for 4-6 hours.

6. The method for preparing a lubricant having a modified silicon carbide particle structure coated with a resin material for drilling fluid according to claim 1, characterized in that: The ultrasonic treatment time in step (3) is 5-7h.

7. The method for preparing a lubricant having a modified silicon carbide particle structure coated with a resin material for drilling fluid according to claim 1, characterized in that: The heating in step (3) is heating to 360°C; and the drying is drying at 60-70°C for 18-30 hours.

8. A lubricant for drilling fluid with a resin-coated modified silicon carbide particle structure, characterized in that: The preparation method according to claim 1 is used for preparation.

9. The lubricant having a modified silicon carbide particle structure coated with a resin material for drilling fluid according to claim 8 is used in drilling fluid as a lubricant in the drilling process to achieve the drilling goal of reducing drag and increasing speed, characterized in that: The specific application is as follows: at the beginning of the drilling operation, a lubricant with a modified silicon carbide particle structure coated with a drilling fluid resin material at a mass concentration of 0.2-1.2wt% is added to the drilling fluid.

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