Drilling fluid lubricating additive as well as preparation method and application thereof

Abstract

The invention relates to a drilling fluid lubricating additive and a preparation method and application thereof.The lubricating additive comprises a lubricating stabilizer, a viscosity modifier, a dispersing agent and an antioxidant, and the lubricating stabilizer is selected from one or more of a modifier of vegetable oil and a modifier of fatty acid; the viscosity modifier is selected from one or more of vegetable wax; and the dispersant is selected from a nonionic surfactant with an HLB value of 13-18. The lubricating additive is prepared by compounding the lubricating stabilizer, the viscosity modifier, the dispersing agent and the antioxidant, and after the lubricating additive is added into the lubricant, the oxidation stability of the lubricant in a high-temperature and high-salt system can be remarkably improved, the problem of reaction precipitates in the aging process is solved, the lubricating effect of the lubricant is improved, and the service life of the lubricant is prolonged. Particularly, the lubricating effect under a high-temperature condition is achieved; the lubricating additive disclosed by the invention is good in stability, excellent in compatibility and very convenient to use.

Description

Technical Field

[0001] The invention relates to the technical field of oil industry drilling, and in particular to a drilling fluid lubricating additive and a preparation method and application thereof. Background Art

[0002] With the exploration and development of deep and ultra-deep oil and gas, high torque and high friction during deep and ultra-deep well drilling have become one of the key issues affecting drilling safety and drilling speed, which poses a greater challenge to the lubricity of drilling fluids under high temperature and high salt conditions.

[0003] The main way to improve the lubricity of drilling fluid is to add lubricants to the drilling fluid. Drilling fluid lubricants can be divided into two categories: solid lubricants and liquid lubricants. Solid lubricants mainly include graphite, plastic balls, glass beads, etc. Since solid lubricants are easy to affect solid phase control and easy to damage the reservoir, they are subject to certain restrictions during use. Compared with solid lubricants, liquid lubricants are more widely used in oil fields, mainly mineral oil lubricants, vegetable oil lubricants, sulfonated tall oil lubricants, polymer alcohol lubricants, etc. With the increasing attention to environmental protection, the current drilling fluid lubricants mainly focus on lubrication efficiency and fluorescence level, and there is less research on multifunctional types such as temperature resistance and salt resistance. Under high temperature, high density, and high mineralization conditions, ordinary lubricants are prone to degradation, oxidation, carbonization, cross-linking, group variation, desorption, dehydration, etc., which will lead to the formation of reaction precipitates and the reduction of lubrication performance. Therefore, it is very important for the drilling lubrication industry to select excellent lubricating additives and solve the above problems on the basis of ensuring the effect of existing lubricant products.

[0004] At present, most researchers improve the temperature and salt resistance of lubricants by adding surfactants, extreme pressure lubricants or modifiers to lubricants, such as patents CN117820667A, CN118562467A or CN109439294B, etc. The innovation points of the above patents are to improve the temperature resistance and lubrication performance of lubricants, and do not involve solving the problem of high-temperature precipitation. In particular, as the drilling strata deepen, the temperature of the working surface becomes higher and higher, and some of the raw materials used will have a weakened high-temperature effect or even fail. In addition, the process flow is complicated and fails to provide convenience for on-site construction. Summary of the invention

[0005] The purpose of the present invention is to provide a drilling fluid lubricating additive and a preparation method and application thereof.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] The invention provides a drilling fluid lubricating additive, comprising a lubricating stabilizer, a viscosity modifier, a dispersant and an antioxidant, wherein the lubricating stabilizer is selected from one or more of modified substances of vegetable oils and modified substances of fatty acids; the viscosity modifier is selected from one or more of vegetable waxes; and the dispersant is selected from a nonionic surfactant with an HLB value of 13 to 18.

[0008] The lubricating stabilizer of the present invention has the characteristics of high flash point, high compatibility, good high temperature resistance, etc. After being used as a lubricating additive component, it can promote the movement between lubricant molecules or between chain segments, and even when some parts of the molecules are bound into a gel network, it can also play a lubricating role and reduce the "friction force" between molecules, so that the molecular chains can slide against each other, and the lubricating stabilizer can also improve the oxidation stability and low temperature compatibility of the lubricating additive; plant wax is a high-carbon fatty acid and high-carbon alcohol ester derived from natural plants, which not only has a stable long-chain structure, but also contains carboxyl groups, alcohol oxygen groups and other structures that first form a protective film during the friction process, and then undergo an esterification reaction on the metal surface and adsorb on the metal. A protective film is formed on the surface, and the lubricating film formed by physical adsorption and chemical reaction during the wear process works together to achieve anti-wear and friction reduction effects; non-ionic surfactants with HLB values ​​of 13 to 18 have good solubilizing, dispersing and wetting effects. The use of this mixture of surfactants can play a dispersing role in high-viscosity combinations such as lubricating stabilizers and vegetable waxes, solving the problem of raw material stratification caused by different freezing points under low temperatures in winter and the northwest region, ensuring both the stability and uniformity of the overall additive and the rapid dispersion after the addition of the lubricant; the addition of antioxidants further enhances the high temperature resistance of the lubricating additive and ensures the stability of the lubricating additive during long-term storage.

[0009] After the lubricating additive of the present invention is added to the liquid lubricant, the oxidation stability of the lubricant in a high-temperature and high-salt system can be significantly improved, the problem of reaction precipitates in the aging process can be solved, and the lubricating effect of the lubricant can be improved; at the same time, the problem of poor dispersibility of the lubricant after being added to the mud and the stratification of the mud after long-term storage can be solved, and the high-stirring dispersibility of the lubricant in the mud can be effectively improved, the stirring time can be shortened, and the stratification of the mud after high-temperature aging after high-speed stirring can be avoided.

[0010] Preferably, the modified vegetable oil is obtained by modifying the vegetable oil by one or more of epoxidation, esterification and acetylation processes. The modified vegetable oil is degradable and more environmentally friendly.

[0011] Further preferably, the vegetable oil includes soybean oil and linseed oil.

[0012] In some embodiments, the modified vegetable oil includes epoxidized soybean oil and epoxidized linseed oil.

[0013] Preferably, the modified fatty acid is obtained by modifying the fatty acid through an esterification process.

[0014] Further preferably, the fatty acid comprises citric acid and sebacic acid.

[0015] More preferably, the fatty acid is extracted from plants.

[0016] In some embodiments, the modified fatty acid is prepared by esterifying the fatty acid with an alcohol having 3 to 10 carbon atoms.

[0017] Furthermore, the alcohol has 4 to 8 carbon atoms, such as butanol and octanol.

[0018] In some embodiments, the modified fatty acid includes tributyl citrate and dioctyl sebacate.

[0019] Preferably, the lubrication stabilizer accounts for 85-92% of the total mass of the lubrication additive, for example 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%.

[0020] Preferably, the vegetable waxes include rice bran wax, palm wax and sunflower seed wax.

[0021] Preferably, the viscosity modifier accounts for 5-12% of the total mass of the lubricating additive, for example, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%.

[0022] Preferably, the nonionic surfactant is selected from one or more of polyoxyethylene alkylphenol ether, polyoxyethylene monostearate (such as polyoxyethylene sorbitan monostearate), polyoxyethylene lauryl ether, and coconut diethanolamide.

[0023] Preferably, the dispersant accounts for 2-5% of the total mass of the lubricating additive, for example, 2%, 3%, 4%, 5%.

[0024] Preferably, the antioxidant is selected from one or more of butylated hydroxytoluene, butylated hydroxyanisole and tert-butylhydroquinone.

[0025] Preferably, the antioxidant accounts for 0.1-0.5% of the total mass of the lubricating additive, for example, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%.

[0026] Preferably, based on the total mass of the lubricating additive being 100%, the proportions of the components of the lubricating additive are as follows:

[0027] Lubricating stabilizer 85-92%;

[0028] Viscosity modifier 5-12%;

[0029] Dispersant 2-5%;

[0030] Antioxidant 0.1~0.5%.

[0031] Further preferably, based on the total mass of the lubricating additive being 100%, the proportions of the components of the lubricating additive are as follows:

[0032] Lubricating stabilizer 86-90%;

[0033] Viscosity modifier 5-10%;

[0034] Dispersant 2-5%;

[0035] Antioxidant 0.1~0.5%.

[0036] The present invention also provides a method for preparing the lubricating additive, comprising the following steps:

[0037] (1) mixing part of the lubricating stabilizer and the viscosity modifier;

[0038] (2) adding a dispersant and an antioxidant to the mixed system of step (1) and mixing;

[0039] (3) Add the remaining lubricating stabilizer to the mixed system of step (2) and mix.

[0040] Preferably, the mixing temperatures of step (1), step (2) and step (3) are independently 60 to 80°C.

[0041] Preferably, the mixing time of step (1) is 20 to 50 min, more preferably 30 to 45 min, and even more preferably 35 to 45 min.

[0042] Preferably, the mixing time of step (2) is 20 to 50 min, more preferably 30 to 45 min, and even more preferably 35 to 45 min.

[0043] Preferably, the mixing time of step (3) is 30 to 80 min, more preferably 30 to 70 min, and even more preferably 50 to 65 min.

[0044] Preferably, the partial lubricating stabilizer accounts for 1 / 3 to 2 / 3 of the total mass of the lubricating additive, more preferably 0.4 to 0.6, and even more preferably 0.5 to 0.6.

[0045] The present invention also provides an application of the lubricating additive, comprising adding the lubricating additive to a lubricant for drilling fluid.

[0046] Preferably, the amount of the lubricant additive added is 5-15% of the total mass of the lubricant, and more preferably 5-10%.

[0047] The present invention also provides a lubricant for drilling fluid, comprising the lubricating additive as described above.

[0048] Preferably, the lubricating additive accounts for 5-10% of the total mass of the lubricant.

[0049] Preferably, based on the total mass of the lubricant being 100%, the lubricant comprises:

[0050] Matrix 85-93%;

[0051] Sorbitan fatty acid ester 1-5%;

[0052] Lubricating additive 5-10%.

[0053] Further preferably, the matrix is ​​selected from one or more of fatty acid methyl esters, fatty acid ethyl esters, and vegetable oils.

[0054] In some embodiments, the vegetable oil includes soybean oil, palm oil, rapeseed oil and corn oil.

[0055] The present invention also provides a method for preparing the lubricant, which comprises mixing a base, a sorbitan fatty acid ester and a lubricating additive.

[0056] Preferably, the mixing time is 20 to 80 min, more preferably 30 to 60 min.

[0057] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0058] The present invention prepares a lubricating additive by compounding a lubricating stabilizer, a viscosity modifier, a dispersant and an antioxidant. After the lubricating additive is added to a lubricant, the oxidation stability of the lubricant in a high-temperature and high-salt system can be significantly improved, the problem of reaction precipitates during the aging process can be solved, and the lubricating effect of the lubricant can be improved, especially the lubricating effect under high-temperature conditions;

[0059] The lubricating additive of the invention has good stability, good compatibility and is very convenient to use. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 This is a physical picture of the lubricating additive and lubricant prepared in Example 1-1;

[0061] Figure 2 This is a comparison chart of the effects of the lubricants of Example 1-1 and Comparative Example 1 after aging at 200°C / 16h. DETAILED DESCRIPTION

[0062] The present invention is further described below in conjunction with the examples. However, the present invention is not limited to the following examples. The implementation conditions used in the examples can be further adjusted according to the different requirements of specific use, and the implementation conditions not specified are conventional conditions in the industry. The technical features involved in each embodiment of the present invention can be combined with each other as long as they do not conflict with each other.

[0063] Unless otherwise specified, the reagents and instruments used in the following examples and comparative examples are all commercially available products, or can be prepared by referring to the prior art. Among them, rice bran wax was purchased from Dongguan Gaobu Fufu Detergent Factory, brand 56#; palm wax was purchased from Shanghai Xiyu Materials Technology Co., Ltd., brand XY-25; sunflower seed wax was purchased from Nanjing Funati Chemical Products Co., Ltd., brand sunflower seed wax;

[0064] Epoxidized soybean oil was purchased from Nanjing Rongji Chemical Co., Ltd., brand epoxy plasticizer; Epoxidized linseed oil was purchased from Dongguan Baojulai Plastic Raw Materials Co., Ltd., brand epoxy plasticizer; Tributyl citrate was purchased from Shandong Boxuan Chemical Co., Ltd., brand plasticizer TBC; Dioctyl sebacate was purchased from Shandong Maofa Chemical Co., Ltd., brand plasticizer DOS;

[0065] Coconut diethanolamide was purchased from Shanghai Chuxing Chemical Co., Ltd., brand 6501; polyoxyethylene lauryl ether was purchased from Jiangsu Hai'an Petrochemical Plant, brand Brij L4; polyoxyethylene monostearate was purchased from Guangdong Warner Chemical Co., Ltd., brand Tween 60; polyoxyethylene alkylphenol ether was purchased from Jiangsu Hai'an Petrochemical Plant, brand OP-10;

[0066] Fatty acid methyl ester was purchased from Suzhou Fengbei, with the brand name of methyl oleate; sorbitan fatty acid ester was purchased from Jiangsu Hai'an Petrochemical Plant, with the brand name of S-85; fatty acid ethyl ester was purchased from Suzhou Fengbei, with the brand name of ethyl oleate.

[0067] Unless otherwise specified, "parts" hereinafter refer to "parts by mass".

[0068] Example 1-1

[0069] A method for preparing a lubricating additive comprises the following steps:

[0070] Step 1: Add 5 parts of rice bran wax and 45 parts of tributyl citrate into a reaction kettle, stir at 300-500 rpm and 60-80° C. for 40 minutes to obtain a mixture A.

[0071] Step 2: Add 5 parts of coconut diethanolamide and 0.1 parts of butylated hydroxytoluene to mixture A, and stir at 300-500 rpm and 60-80° C. for 40 minutes to obtain mixture B.

[0072] Step 3: Add 44.9 parts of tributyl citrate to mixture B, stir at 300-500 rpm and 60-80° C. for 60 minutes, and then cool to room temperature to obtain mixture C.

[0073] A use of a lubricating additive in a lubricant comprises: adding 97 parts of industrial-grade mixed oil (composed of 30 parts of soybean oil, 20 parts of rapeseed oil and 47 parts of corn oil), 3 parts of dehydrated sorbitan fatty acid ester and 10 parts of mixture C into a reaction kettle, stirring at 800 to 1000 rpm and 40 to 60° C. for 60 minutes and then cooling to room temperature to obtain lubricant 1-1.

[0074] The actual picture of the lubricating additive and lubricant in this embodiment is as follows Figure 1 shown.

[0075] Example 1-2

[0076] This embodiment is basically the same as embodiment 1-1, except that:

[0077] In the application of the lubricant additive in the lubricant, the addition amount of mixture C was reduced to 5 parts to obtain lubricant 1-2.

[0078] Examples 1-3

[0079] This embodiment is basically the same as embodiment 1-1, except that:

[0080] In the application of the lubricant additive in the lubricant, the stirring time was reduced to 30 minutes, resulting in Lubricants 1-3.

[0081] Example 2-1

[0082] A method for preparing a lubricating additive comprises the following steps:

[0083] Step 1: Add 10 parts of palm wax and 45 parts of epoxidized soybean oil into a reaction kettle, stir at 300-500 rpm and 60-80° C. for 30 minutes to obtain a mixture A.

[0084] Step 2: Add 3 parts of polyoxyethylene lauryl ether and 0.3 parts of butylated hydroxyanisole to mixture A, and stir at 300-500 rpm and 60-80° C. for 30 minutes to obtain mixture B.

[0085] Step 3: Add 41.7 parts of epoxidized soybean oil to mixture B, stir at 300-500 rpm and 60-80° C. for 50 minutes, and then cool to room temperature to obtain mixture C.

[0086] A use of a lubricating additive in a lubricant comprises: adding 97 parts of fatty acid methyl ester, 3 parts of sorbitan fatty acid ester, and 8 parts of mixture C into a reaction kettle, stirring at 800 to 1000 rpm, 40 to 60° C. for 50 minutes, and then cooling to room temperature to obtain lubricant 2-1.

[0087] Example 2-2

[0088] This embodiment is basically the same as embodiment 2-1, except that:

[0089] In the application of the lubricant additive in the lubricant, the addition amount of mixture C was reduced to 6 parts to obtain lubricant 2-2.

[0090] Example 2-3

[0091] This embodiment is basically the same as embodiment 2-1, except that:

[0092] In the application of the lubricant additive in the lubricant, the stirring time was reduced to 30 minutes, resulting in Lubricant 2-3.

[0093] Example 3-1

[0094] The preparation method of the lubricating additive comprises the following steps:

[0095] Step 1: Add 8 parts of sunflower seed wax and 50 parts of epoxy linseed oil into a reaction kettle, stir at 300-500 rpm and 60-80° C. for 30 minutes to obtain a mixture A.

[0096] Step 2: Add 4 parts of polyoxyethylene monostearate and 0.2 parts of tert-butylhydroquinone to mixture A, and stir at 300-500 rpm and 60-80° C. for 30 minutes to obtain mixture B.

[0097] Step 3: Add 37.8 parts of dioctyl sebacate to mixture B, stir at 300-500 rpm and 60-80° C. for 40 minutes, and then cool to room temperature to obtain mixture C.

[0098] A use of a lubricating additive in a lubricant comprises: adding 98 parts of fatty acid ethyl ester, 2 parts of sorbitan fatty acid ester, and 7 parts of mixture C into a reaction kettle, stirring at 800 to 1000 rpm, 40° C. to 60° C. for 40 minutes, and then cooling to room temperature to obtain lubricant 3-1.

[0099] Example 3-2

[0100] This embodiment is basically the same as embodiment 3-1, except that:

[0101] In the application of the lubricant additive in the lubricant, the addition amount of the mixture C was reduced to 5 parts to obtain lubricant 3-2.

[0102] Example 3-3

[0103] This embodiment is basically the same as embodiment 3-1, except that:

[0104] In the application of the lubricant additive in the lubricant, the stirring time was reduced to 30 minutes, resulting in lubricant 3-3.

[0105] Example 4-1

[0106] A method for preparing a lubricating additive comprises the following steps:

[0107] Step 1: Add 3 parts of rice bran wax, 3 parts of palm wax, and 50 parts of tributyl citrate into a reaction kettle, and stir at 300-500 rpm and 60-80° C. for 30 minutes to obtain a mixture A.

[0108] Step 2: Add 2 parts of coconut diethanolamide, 2 parts of polyoxyethylene alkylphenol ether, and 0.2 parts of butylated hydroxyanisole to mixture A, and stir at 300-500 rpm and 60-80° C. for 30 minutes to obtain mixture B.

[0109] Step 3: Add 39.8 parts of dioctyl sebacate to mixture B, stir at 300-500 rpm and 60-80° C. for 30 minutes, and then cool to room temperature to obtain mixture C.

[0110] A use of a lubricating additive in a lubricant comprises adding 56 parts of industrial-grade mixed oil (composed of 20 parts of soybean oil and 36 parts of palm oil), 40 parts of fatty acid methyl ester, 4 parts of sorbitan fatty acid ester and 9 parts of mixture C into a reaction kettle, stirring at 800 to 1000 rpm and 40° C. to 60° C. for 60 minutes and then cooling to room temperature to obtain a lubricant 4-1.

[0111] Example 4-2

[0112] This embodiment is basically the same as embodiment 4-1, except that:

[0113] In the application of the lubricant additive in the lubricant, the addition amount of mixture C was reduced to 6 parts to obtain lubricant 4-2.

[0114] Example 4-3

[0115] This embodiment is basically the same as embodiment 3-1, except that:

[0116] In the application of the lubricant additive in the lubricant, the stirring time was reduced to 40 minutes, resulting in lubricant 4-3.

[0117] Comparative Example 1

[0118] A method for preparing a lubricant comprises: adding 97 parts of industrial-grade mixed oil (composed of 30 parts of soybean oil, 20 parts of rapeseed oil and 47 parts of corn oil) and 3 parts of sorbitan fatty acid ester into a reaction kettle, stirring at 800-1000 rpm and 40-60° C. for 60 minutes to obtain a mixture.

[0119] Comparative Example 2

[0120] A method for preparing a lubricant comprises: adding 97 parts of fatty acid methyl ester and 3 parts of sorbitan fatty acid ester into a reaction kettle, stirring at 800-1000 rpm and 40-60° C. for 60 minutes to obtain a mixture.

[0121] Comparative Example 3

[0122] A method for preparing a lubricant comprises: adding 98 parts of fatty acid ethyl ester and 2 parts of sorbitan fatty acid ester into a reaction kettle, stirring at 800-1000 rpm and 40-60° C. for 60 minutes to obtain a mixture.

[0123] Comparative Example 4

[0124] A method for preparing a lubricant comprises: adding 56 parts of industrial-grade mixed oil (composed of 20 parts of soybean oil and 36 parts of palm oil), 40 parts of fatty acid methyl ester and 4 parts of sorbitan fatty acid ester into a reaction kettle, stirring at 800-1000 rpm and 40-60°C for 60 minutes to obtain a mixture.

[0125] Comparative Example 5

[0126] This comparative example is basically the same as Example 1-1, except that tributyl citrate is replaced with dioctyl phthalate (Shandong Defa Chemical Co., Ltd., brand plasticizer DOP (DEHP)).

[0127] Comparative Example 6

[0128] This comparative example is substantially the same as Example 1-1, except that no rice bran wax is added.

[0129] Comparative Example 7

[0130] This comparative example is substantially the same as Example 1-1, except that no coconut diethanolamide is added.

[0131] Comparative Example 8

[0132] This comparative example is substantially the same as Example 1-1, except that coconut diethanolamide is replaced with castor oil polyoxyethylene ether (Jiangsu Haian Petrochemical Plant, brand EL-10, HLB value less than 13).

[0133] Comparative Example 9

[0134] This comparative example is substantially the same as Example 1-1, except that coconut diethanolamide is replaced with polyethylene glycol oleate (produced by Jiangsu Hai'an Petrochemical Plant, brand PEG6000MO, HLB value greater than 18).

[0135] Comparative Example 10

[0136] This embodiment is basically the same as embodiment 1-1, except that:

[0137] In the preparation method of the lubricating additive, the raw material ratios are different, specifically: 31.5 parts of rice bran wax; 60 parts of tributyl citrate; 8 parts of coconut diethanolamide; and 0.5 parts of butylated hydroxytoluene.

[0138] Product performance verification

[0139] 1. Verification of lubricant effect

[0140] 1.1. Prepare two portions of bentonite-based slurry (300 mL of distilled water, 0.6 g of anhydrous sodium carbonate, and 15 g of sodium bentonite), stir at high speed for 20 min, interrupt at least twice to scrape off the adherents on the cup wall, and seal and cure at (25°C ± 1°C) for 24 hours to make its apparent viscosity reach (13-15) mPa.s. If it cannot be reached, adjust the amount of bentonite appropriately.

[0141] 1.2. Prepare two portions of bentonite-based slurry according to the method in 1.1. Add 12.0 g (accurate to 0.01 g, the same below) of sodium chloride to each portion of bentonite-based slurry and stir at high speed for 5 minutes to obtain a 4% salt water-based slurry.

[0142] 1.3. Take one portion of the 4% salt water-based slurry and stir it at high speed for 5 minutes, then put it into a high-temperature aging tank. Add 3g of the sample to the other portion of the 4% salt water-based slurry, stir it at high speed for 5 minutes, then put it into a high-temperature aging tank. Roll the two portions of slurry at 200°C for 16 hours, cool to room temperature, transfer them to high-speed stirring cups respectively, stir them at high speed for 5 minutes, and determine the lubrication coefficient using an extreme pressure lubrication instrument.

[0143] 1.4. Determination of lubrication coefficient According to the method of SY / T 6094, read the reading of the extreme pressure lubrication instrument when it is pressurized and rotated for 5 minutes, and calculate the lubrication coefficient. The reduction rate of lubrication coefficient after hot rolling is calculated according to the formula R1 = (K0-K2) / K0×100%. In the formula: R1 is the reduction rate of lubrication coefficient, %; K0 is the lubrication coefficient of the base slurry before or after hot rolling; K2 is the lubrication coefficient of the sample slurry before or after hot rolling.

[0144] 1.5. The embodiments and comparative examples were subjected to aging test at 200°C / 16h. The results are shown in Table 1 below. For photos of some embodiments and comparative examples, see Figure 2 .

[0145] Table 1

[0146]

[0147]

[0148]

[0149] In the above table, the lubrication coefficients of the embodiments and comparative examples after aging at 200℃ / 16h are the data of repeated detection twice. The smaller the lubrication coefficient after aging, the better the lubrication performance of the lubricating oil; the first two items of the lubrication coefficient reduction rate of the embodiments and comparative examples after aging at 200℃ / 16h are the data of repeated detection twice, and the last item is the average value. The greater the lubrication coefficient reduction rate after aging, the better. The method for determining the mud dispersion effect includes: stirring the aged mud sample at high speed for 5 minutes, standing at room temperature of 25℃ for 24 hours, and observing the mud dispersion effect.

[0150] As can be seen from the above table, when the lubricating additive of the present invention is used to prepare lubricants, even under a shorter stirring time (30 minutes), a lubricant of good quality can be prepared. The lubricating additive of the present invention reduces the stirring time for preparing lubricants, and can be used as a separate external additive, which is particularly suitable for use on construction sites, is easy to use, and has low production costs. In addition, it can also improve the high-stirring dispersibility of the lubricant in the mud, and the mud after high-temperature aging will not stratify after high-stirring for a long time.

[0151] From the above table and Figure 2 It can be seen that the salt water-based slurry without the addition of lubricating additives showed black precipitates after aging at 200°C / 16h, while the salt water-based slurry with the addition of lubricating additives did not show black precipitates and had better lubrication performance, indicating that when the lubricating additives of the present invention are added to the lubricant, the carbonization and even oxidation of the lubricant at high temperature can be inhibited.

[0152] The above detailed description of the present invention is intended to enable persons familiar with the art to understand the contents of the present invention and implement them. It does not limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A drilling fluid lubricating additive, characterized in that: The lubricating additive comprises a lubricating stabilizer, a viscosity modifier, a dispersant and an antioxidant, wherein the lubricating stabilizer is selected from one or more of modified vegetable oils and modified fatty acids; the viscosity modifier is selected from one or more of vegetable waxes; and the dispersant is selected from nonionic surfactants with an HLB value of 13 to 18.

2. The drilling fluid lubricating additive according to claim 1, characterized in that: The modified vegetable oil is obtained by modifying the vegetable oil by one or more of epoxidation, esterification and acetylation processes, and the vegetable oil includes soybean oil and linseed oil; and / or, The modified fatty acid is obtained by modifying the fatty acid through an esterification process, and the fatty acid includes citric acid and sebacic acid.

3. The drilling fluid lubricating additive according to claim 2, characterized in that: The modified vegetable oil includes epoxidized soybean oil and epoxidized linseed oil; and / or, The fatty acids are extracted from plants; and / or, The modified fatty acids include tributyl citrate and dioctyl sebacate.

4. The drilling fluid lubricating additive according to claim 1, characterized in that: The lubricating stabilizer accounts for 85-92% of the total mass of the lubricating additive.

5. The drilling fluid lubricating additive according to claim 1, characterized in that: The vegetable waxes include rice bran wax, palm wax and sunflower seed wax; and / or, The viscosity modifier accounts for 5-12% of the total mass of the lubricating additive.

6. The drilling fluid lubricating additive according to claim 1, characterized in that: The nonionic surfactant is selected from one or more of polyoxyethylene alkylphenol ether, polyoxyethylene monostearate, polyoxyethylene lauryl ether, and coconut diethanolamide; and / or, The dispersant accounts for 2-5% of the total mass of the lubricating additive.

7. The drilling fluid lubricating additive according to claim 1, characterized in that: The antioxidant is selected from one or more of butylated hydroxytoluene, butylated hydroxyanisole, and tert-butylhydroquinone; and / or, The antioxidant accounts for 0.1-0.5% of the total mass of the lubricating additive.

8. The drilling fluid lubricating additive according to any one of claims 1 to 7, characterized in that: Taking the total mass of the lubricating additive as 100%, the proportions of the components of the lubricating additive are as follows: Lubricating stabilizer 85-92%; Viscosity modifier 5-12%; Dispersant 2-5%; Antioxidant 0.1~0.5%.

9. The method for preparing the lubricating additive according to any one of claims 1 to 8, characterized in that: The preparation method comprises the following steps: (1) mixing part of the lubricating stabilizer and the viscosity modifier; (2) adding a dispersant and an antioxidant to the mixed system of step (1) and mixing; (3) Add the remaining lubricating stabilizer to the mixed system of step (2) and mix.

10. The method for preparing the lubricating additive according to claim 9, characterized in that: The mixing temperatures of step (1), step (2) and step (3) are independently 60 to 80°C.

11. The use of the lubricating additive according to any one of claims 1 to 8, characterized in that: The lubricating additive is added to the lubricant for drilling fluid.

12. A lubricant for drilling fluid, characterized in that: Includes the lubricating additive as described in any one of claims 1 to 8.

13. The lubricant for drilling fluid according to claim 12, characterized in that: The lubricating additive accounts for 5-10% of the total mass of the lubricant.

14. The lubricant for drilling fluid according to claim 12, characterized in that: Taking the total mass of the lubricant as 100%, the lubricant comprises: Matrix 85-93%; Sorbitan fatty acid ester 1-5%; Lubricating additives 5-10%, The matrix is ​​selected from one or more of fatty acid methyl ester, fatty acid ethyl ester and vegetable oil.

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