Lubricant and Its Preparation Method and Application

Abstract

The present invention relates to the field of lubricating materials, and particularly relates to a lubricant and its preparation method and application. The lubricant comprises a base oil, an emulsifier and an antioxidant. Among them, the base oil comprises a gas-to-liquid oil and / or a petroleum hydrotreated light fraction; the emulsifier comprises a polyether with a structural unit content of 5% to 85 wt% from ethylene oxide and a structural unit content of 15% to 95 wt% from propylene oxide. This lubricant has excellent lubricity, stability and environmental friendliness, and is not prone to foaming.

Description

Technical Field

[0001] The present invention relates to the field of lubricating materials, and particularly relates to a lubricant, a preparation method thereof, and an application thereof. Background Art

[0002] Drilling fluid lubricants are mainly used to reduce the frictional resistance between the drill string and the wellbore, avoid drilling accidents such as pipe sticking, and improve drilling efficiency. In recent years, with the emergence of deep wells, ultra-deep wells, extended reach wells, etc., higher requirements have been put forward for drilling fluid lubricants. At the same time, with the strict environmental protection requirements, it is necessary to develop a highly efficient, green, and safe drilling fluid lubricant.

[0003] Drilling fluid lubricants include solid types and liquid types. Solid lubricants are mainly plastic balls, glass balls, and graphite powder, which are mainly used for casing running operations. These materials are easily removed by solids control equipment during drilling and are not suitable for use during drilling. Liquid lubricants include mineral oil and vegetable oil lubricants. Mineral oil mainly includes diesel oil, paraffin oil, white oil, etc. containing aromatics, which will cause environmental pollution problems and affect geological logging.

[0004] Vegetable oils and their derivatives are currently the mainstream products of lubricants in drilling operations, but vegetable oil lubricants have obvious defects, including general lubrication effect; easy to undergo esterification reaction at higher pH values, losing lubricity while foaming; there are double bonds in vegetable oils, which are easily degraded and oxidized at high temperatures and lose lubricity. Summary of the Invention

[0005] The purpose of the present invention is to overcome the problems of easy foaming, poor lubricity, stability, and environmental friendliness of lubricants existing in the prior art, and provide a lubricant, a preparation method thereof, and an application thereof. The lubricant has the characteristics of not being easy to foam, excellent lubrication performance, stability, and environmental friendliness.

[0006] To achieve the above purpose, in the first aspect of the present invention, a lubricant is provided. The lubricant includes a base oil, an emulsifier, and an antioxidant, wherein,

[0007] The base oil includes gas-to-liquid oil and / or petroleum hydrotreated light distillate;

[0008] The emulsifier includes a polyether with a structural unit content of 5% - 85wt% from ethylene oxide and a structural unit content of 15% - 95wt% from propylene oxide.

[0009] In the second aspect of the present invention, a preparation method of the lubricant is provided. The method includes:

[0010] a. First mix the base oil and the antioxidant to prepare a blend;

[0011] b. Secondarily mix the blend with an emulsifier to prepare a lubricant.

[0012] The third aspect of the present invention provides an application of the described lubricant in the technical field of oil drilling engineering.

[0013] Through the above technical solutions, the present invention has at least the following beneficial effects:

[0014] By compounding a base oil including gas-to-liquid oil and / or light fraction of petroleum hydrofining and a polyether with a structural unit content of ethylene oxide of 5% - 85 wt% and a structural unit content of propylene oxide of 15% - 95 wt% and an antioxidant, the formed lubricant has excellent lubricity, stability and environmental friendliness, and is not prone to foaming.

[0015] The lubricant of the present invention can effectively reduce the drilling torque and the friction during tripping, and is particularly suitable for the technical field of oil drilling engineering. Detailed Embodiments

[0016] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0017] The first aspect of the present invention provides a lubricant, which includes a base oil, an emulsifier and an antioxidant, wherein,

[0018] the base oil includes gas-to-liquid oil and / or light fraction of petroleum hydrofining;

[0019] the emulsifier includes a polyether with a structural unit content of ethylene oxide of 5% - 85 wt% and a structural unit content of propylene oxide of 15% - 95 wt%.

[0020] By compounding a base oil including gas-to-liquid oil and / or light fraction of petroleum hydrofining and a polyether emulsifier with a structural unit content of ethylene oxide of 5% - 85 wt% and a structural unit content of propylene oxide of 15% - 95 wt% and an antioxidant, the formed lubricant has excellent lubricity, stability and environmental friendliness, and is not prone to foaming.

[0021] According to a preferred embodiment of the present invention, the emulsifier includes a polyether with a structural unit content of ethylene oxide of 5% - 15 wt% and a structural unit content of propylene oxide of 85% - 95 wt%. By adopting the foregoing preferred scheme, the lubricity, stability and environmental friendliness of the lubricant, as well as the foam suppression effect, can be further improved.

[0022] In the present invention, the base oil can be a conventional choice in the art. According to a preferred embodiment of the present invention, the flash point of the base oil is above 80 °C, and the aromatic hydrocarbon content is above 500 mg / kg; preferably, the biodegradation rate of the base oil in seawater for 28 days is above 70%. By adopting the foregoing preferred scheme, the environmental friendliness of the lubricant can be further improved.

[0023] In the present invention, as long as the object of the present invention can be achieved, there is no particular limitation on the number average molecular weight of the emulsifier. According to a preferred embodiment of the present invention, the number average molecular weight of the emulsifier is 1600-2300 g·mol -1 . By adopting the foregoing preferred scheme, the lubricity, stability and environmental friendliness of the lubricant, as well as the foam suppression effect, can be further improved.

[0024] According to a preferred embodiment of the present invention, the thermal decomposition temperature of the emulsifier is above 250 °C, and the cloud point is 20-30 °C. By adopting the foregoing preferred scheme, the stability and environmental friendliness of the lubricant, as well as the foam suppression effect, can be further improved.

[0025] In the present invention, the antioxidant can be a conventional choice in the art. According to a preferred embodiment of the present invention, the antioxidant is alkylated diphenylamine. By adopting the foregoing preferred scheme, the lubricity and stability of the lubricant, as well as the foam suppression effect, can be further improved.

[0026] According to a preferred embodiment of the present invention, the alkylated diphenylamine is selected from at least one of diisobutylene diphenylamine, di-tert-butyl-p-cresol, tert-butyl-p-hydroxyanisole, and propyl gallate, preferably diisobutylene diphenylamine. By adopting the foregoing preferred scheme, the lubricity and stability of the lubricant, as well as the foam suppression effect, can be further improved.

[0027] According to a preferred embodiment of the present invention, the diisobutylene diphenylamine is synthesized by alkylation reaction using diisobutylene and diphenylamine as raw materials under the action of activated clay catalyst.

[0028] In the present invention, as long as the object of the present invention can be achieved, there is no particular limitation on the content of each substance in the lubricant. According to a preferred embodiment of the present invention, based on 100 parts by volume of the lubricant, it includes: 70-90 parts of base oil; 10-30 parts of emulsifier; 0.2-0.5 parts of antioxidant. By adopting the foregoing preferred scheme, the lubricity and stability of the lubricant, as well as the foam suppression effect, can be further improved.

[0029] According to a preferred embodiment of the present invention, the reduction rate of the extreme pressure lubrication coefficient of the lubricant is not less than 98.5%.

[0030] The second aspect of the present invention provides a method for preparing the lubricant, which method comprises:

[0031] a. First mixing the base oil with an antioxidant to obtain a blend;

[0032] b. Second mixing the blend with an emulsifier to obtain the lubricant.

[0033] By preparing the lubricant through this method, the lubricity, stability and foam suppression effect of the lubricant can be further improved.

[0034] In the present invention, the conditions for the first mixing can be conventional selections in the art. According to a preferred embodiment of the present invention, the conditions for the first mixing include: the stirring speed is 5000 - 15000 r / min, and the stirring time is 5 - 20 min.

[0035] In the present invention, the conditions for the second mixing can be conventional selections in the art. According to a preferred embodiment of the present invention, the conditions for the second mixing include: the stirring speed is 5000 - 15000 r / min, and the stirring time is 5 - 20 min.

[0036] The third aspect of the present invention provides an application of the lubricant in the technical field of oil drilling engineering.

[0037] In the present invention, the method for testing the structural unit content is infrared, mass spectrometry, and nuclear magnetic resonance experimental analysis;

[0038] The method for testing the flash point is GB / T27847-2011 Petroleum products - Determination of flash point - Abel-Pensky closed cup method;

[0039] The method for testing the biodegradation rate is the seawater BODIS evaluation method;

[0040] The method for testing the thermal decomposition temperature is GB / T 13464-92 Thermal analysis test method for the thermal stability of substances;

[0041] The method for testing the extreme pressure lubrication coefficient is SY / T6094-94 Evaluation procedure for lubricants used in drilling fluids;

[0042] The apparent viscosity is tested according to GB / T16783.2-2012 Petroleum and natural gas industries - Field testing of drilling fluids - Part 1: Testing of water-based drilling fluids.

[0043] The present invention will be described in detail below through examples. In the following examples, the gas-to-liquid fuel is a commercially available product with the brand of EDC95-11 from Total France; the foam suppression emulsifier (polyether) is a commercially available product from Yangzi Petrochemical BASF Company; the high-temperature antioxidant (diisobutylene diphenylamine) is a commercially available product from Jinzhou Shengda Chemical Co., Ltd.

[0044] Example 1

[0045] The preparation of lubricant A includes the following steps:

[0046] a. Take 75 parts by volume of base oil (gasoline oil, flash point 80°C, aromatic content 500 mg / kg, biodegradation rate in seawater for 28 days 70%) and place it in a high-speed stirring cup. Add 0.2 parts by volume of antioxidant (diisobutylene diphenylamine), and stir at a speed of 12000 r / min for 10 min to obtain a blend;

[0047] b. Add 25 parts by volume of emulsifier (polyether with a structural unit content of 10 wt% from ethylene oxide and 90 wt% from propylene oxide, number average molecular weight 2000 g·mol -1 , thermal decomposition temperature 250°C, cloud point 25°C) to the blend, and stir at a speed of 12000 r / min for 10 min to prepare lubricant A.

[0048] The extreme pressure lubrication coefficient reduction rate is 98.5%, and the anti-temperature can reach 230°C.

[0049] Performance test:

[0050] 1. Influence of lubricant on the apparent viscosity and lubrication coefficient of bentonite slurry:

[0051] Prepare pre-hydrated bentonite slurry with the formula: fresh water + soda ash + bentonite powder (where the concentration of soda ash is 2 g / L of fresh water and the concentration of bentonite powder is 50 g / L of fresh water). After pre-hydrating for 24 hours, the apparent viscosity, extreme pressure lubrication coefficient changes, and foaming situation of the drilling fluid were measured for the pre-hydrated bentonite slurry and the pre-hydrated bentonite slurry after high-temperature aging at 230°C for 16 hours before and after adding lubricant A, respectively, after stirring at 12000 revolutions per minute for 10 minutes. The results are shown in Table 1.

[0052] Table 1

[0053]

[0054] 2. Influence of saturated brine on the foaming of lubricant:

[0055] Prepare saturated sodium chloride brine drilling fluid with the formula: fresh water + soda ash + bentonite + polyanionic cellulose + sodium chloride (where the concentration of soda ash is 2 g / L of fresh water, the concentration of bentonite is 30 g / L of fresh water, the concentration of polyanionic cellulose is 3 g / L of fresh water, and the concentration of sodium chloride is 297 g / L of fresh water). The foaming situation was measured before and after adding lubricant A after stirring at 12000 revolutions per minute for 10 minutes. The results are shown in Table 2.

[0056] Table 2

[0057] Foaming situation Saturated brine drilling fluid None Mixture of saturated brine drilling fluid + Lubricant A (concentration of Lubricant A in fresh water is 10 g / L) None

[0058] 3. Influence of solution pH value on the foaming of lubricants:

[0059] Solutions with pH values of 10, 11, 12, and 13 were prepared using fresh water. The formula was: fresh water + caustic soda. The foaming conditions were measured after stirring at 12,000 revolutions per minute for 10 minutes after adding Lubricant A. The results are shown in Table 3.

[0060] Table 3 Influence of solutions with different pH values on the foaming of lubricants

[0061]

[0062]

[0063] It can be seen from Tables 1 - 3 that the reduction rate of the extreme pressure lubrication coefficient of Lubricant A is 98.5%, the anti - temperature can reach 230°C, it is not easy to foam, has little influence on the rheological properties of drilling fluid; it resists saturated brine and does not easily foam when adding alkali.

[0064] Example 2

[0065] The preparation of Lubricant B includes the following steps:

[0066] a. Take 70 parts by volume of base oil (petroleum hydrotreated light fraction, flash point 83°C, aromatic content 350 mg / kg, 28 - day biodegradation rate in seawater 70%) and place it in a high - speed stirring cup. Add 0.5 parts by volume of antioxidant (diisobutylene diphenylamine), and stir at 12,000 r / min for 10 min to obtain a blend;

[0067] b. Add 30 parts by volume of emulsifier (polyether with a structural unit content of 5 wt% from ethylene oxide and 95 wt% from propylene oxide, number - average molecular weight 2300 g·mol -1 −1, thermal decomposition temperature 250°C, cloud point 22°C) to the blend, and stir at 12,000 r / min for 10 min to prepare Lubricant B.

[0068] The reduction rate of the extreme pressure lubrication coefficient is 98.7%, and the anti - temperature can reach 230°C.

[0069] Example 3

[0070] The preparation of Lubricant C includes the following steps:

[0071] a. Take 90 parts by volume of base oil (gas - made oil, flash point 80°C, aromatic content 500 mg / kg, 28 - day biodegradation rate in seawater 70%) and place it in a high - speed stirring cup. Add 0.3 parts by volume of antioxidant (diisobutylene diphenylamine), and stir at 12,000 r / min for 10 min to obtain a blend;

[0072] b. Add 10 parts by volume of an emulsifier (a polyether with a structural unit content of 15 wt% from ethylene oxide and 85 wt% from propylene oxide, a number average molecular weight of 1600 g·mol -1 , a thermal decomposition temperature of 250 °C, and a cloud point of 28 °C) and stir at 12,000 r / min for 10 min to prepare lubricant C.

[0073] The reduction rate of the extreme pressure lubrication coefficient is 98.8%, and the temperature resistance can reach 230 °C.

[0074] Example 4

[0075] Same as Example 1, except that the number average molecular weight of the emulsifier is 1000 g·mol -1 , to prepare lubricant D. The reduction rate of the extreme pressure lubrication coefficient is 91.5%, and the temperature resistance can reach 220 °C.

[0076] Example 5

[0077] Same as Example 1, except that the antioxidant is di-tert-butyl-p-cresol, to prepare lubricant E. The reduction rate of the extreme pressure lubrication coefficient is 91.4%, and the temperature resistance can reach 200 °C.

[0078] Example 6

[0079] Same as Example 1, except that there are 50 parts by volume of base oil; 50 parts by volume of emulsifier; 0.1 part by volume of antioxidant, to prepare lubricant F. The reduction rate of the extreme pressure lubrication coefficient is 91.5%, and the temperature resistance can reach 210 °C.

[0080] Example 7

[0081] Same as Example 1, except that no antioxidant is added, to prepare lubricant G. The reduction rate of the extreme pressure lubrication coefficient is 92.5%, and the temperature resistance can reach 180 °C.

[0082] Example 8

[0083] Same as Example 1, except that the structural unit content of the polyether from ethylene oxide is 85 wt% and the structural unit content from propylene oxide is 15 wt%, to prepare lubricant H. The reduction rate of the extreme pressure lubrication coefficient is 91.5%, and the temperature resistance can reach 230 °C.

[0084] Comparative Example 1

[0085] Same as Example 1, except that the base oil is vegetable cottonseed oil, to prepare lubricant I. The reduction rate of the extreme pressure lubrication coefficient is 86.5%, and the temperature resistance can reach 130 °C.

[0086] Comparative Example 2

[0087] Same as Example 1, except that the content of the structural unit derived from ethylene oxide in the polyether is 90 wt%, and the content of the structural unit derived from propylene oxide is 10 wt%, to prepare lubricant J. The reduction rate of the extreme pressure lubrication coefficient is 85.5%, and the anti-temperature can reach 190 °C.

[0088] Example 9

[0089] The Nanchuan shale gas oilfield is located in Nanchuan, Chongqing. The main purpose is to develop the shale gas in the Longmaxi Formation. In the second opening of this oilfield, water-based drilling fluid is used for drilling. The drilling interval is 900 - 3000 m, and the open hole section is 2700 m. The formations of Changxing Formation, Longtan Formation, Maokou Formation, Qixia Formation, Liangshan Formation, Hanjiadian Formation, and Xiaoheba Formation are drilled through. The main problems faced are the long open hole section, strong water sensitivity of the nearly 700 m long mudstone formation in the Hanjiadian Formation, serious solid phase pollution of the drilling fluid, and easy mud packing of the drill bit; when drilling directionally in the Hanjiadian Formation and Xiaoheba Formation, the downhole friction is large and the drag is serious, resulting in slow mechanical drilling speed.

[0090] Same platform wells: Shengye 14-2 well, Shengye 14-3 well, Shengye 14-4 well, Shengye 14-5 well, Shengye 14-6 well, Shengye 14-7 well, Shengye 14-8 well, Shengye 14-9 well, Shengye 14-10 well, Shengye 14-11 well, with the same actual drilling performance: ρ: 1.35 g / cm 3 , FV: 56 s, PV: 26 mPa·s, YP: 12 Pa, GEL: 3 / 10 Pa, API FL: 5 mL; among them,

[0091] The potassium chloride polymer drilling fluid formula used in the Shengye 14-2 well is: fresh water + bentonite + soda ash + KPAM + ammonium salt + low-viscosity polyanionic cellulose + KCL + anti-collapse agent + lubricant J + barite (where the concentration of bentonite is 30 g / L fresh water, the concentration of soda ash is 2 g / L fresh water, the concentration of KPAM is 3 g / L fresh water, the concentration of ammonium salt is 10 g / L fresh water, the concentration of low-viscosity polyanionic cellulose is 5 g / L fresh water, the concentration of KCL is 50 g / L fresh water, the concentration of anti-collapse agent is 20 g / L fresh water, the concentration of lubricant J is 20 g / L fresh water, and the concentration of barite is 58.8 g / L fresh water); during the drilling process, the drilling fluid foams seriously, the solid phase pollution of the drilling fluid is serious, the drilling speed is slow, and the drill bit is severely mud-packed. When drilling directionally in the Hanjiadian Formation and Xiaoheba Formation, the downhole friction is large and the drag is serious, and the friction during tripping is 30 - 40 tons, resulting in slow mechanical drilling speed.

[0092] The potassium chloride polymer drilling fluid used in Well Shengye 14-3 is different from the potassium chloride polymer drilling fluid used in Well Shengye 14-2 in that lubricant J is replaced with an equal amount of lubricant I; during the drilling process, the drilling fluid foams severely, the solid phase of the drilling fluid is seriously polluted, the drilling speed is slow, and the bit is severely mud-packed. When drilling directionally in the Hanjiadian Formation and the Xiaoheba Formation, the downhole friction is large, the pipe sticking is serious, and the friction during tripping is 30-40 tons, resulting in a slow mechanical drilling speed.

[0093] The potassium chloride polymer drilling fluid used in Well Shengye 14-4 is different from the potassium chloride polymer drilling fluid used in Well Shengye 14-2 in that lubricant J is replaced with lubricant H; during the drilling process, there are no bubbles in the drilling fluid; when drilling through the strongly water-sensitive formation of the Hanjiadian Formation, there is no bit mud-packing phenomenon. When drilling directionally in the Hanjiadian Formation and the Xiaoheba Formation, the downhole friction is normal, there is no pipe sticking phenomenon, and the friction during tripping with the anti-foaming lubricant is 20-30 tons. The mechanical drilling speed is 20% higher than that of Well Shengye 14-2.

[0094] The potassium chloride polymer drilling fluid used in Well Shengye 14-5 is different from the potassium chloride polymer drilling fluid used in Well Shengye 14-2 in that lubricant J is replaced with lubricant G; during the drilling process, there are no bubbles in the drilling fluid; when drilling through the strongly water-sensitive formation of the Hanjiadian Formation, there is no bit mud-packing phenomenon. When drilling directionally in the Hanjiadian Formation and the Xiaoheba Formation, the downhole friction is normal, there is no pipe sticking phenomenon, and the friction during tripping with the anti-foaming lubricant is 20-30 tons. The mechanical drilling speed is 20% higher than that of Well Shengye 14-2.

[0095] The potassium chloride polymer drilling fluid used in Well Shengye 14-6 is different from the potassium chloride polymer drilling fluid used in Well Shengye 14-2 in that lubricant J is replaced with lubricant F; during the drilling process, there are no bubbles in the drilling fluid; when drilling through the strongly water-sensitive formation of the Hanjiadian Formation, there is no bit mud-packing phenomenon. When drilling directionally in the Hanjiadian Formation and the Xiaoheba Formation, the downhole friction is normal, there is no pipe sticking phenomenon, and the friction during tripping with the anti-foaming lubricant is 20-30 tons. The mechanical drilling speed is 20% higher than that of Well Shengye 14-2.

[0096] The potassium chloride polymer drilling fluid used in Well Shengye 14-7 is different from the potassium chloride polymer drilling fluid used in Well Shengye 14-2 in that lubricant J is replaced with lubricant E; during the drilling process, there are no bubbles in the drilling fluid; when drilling through the strongly water-sensitive formation of the Hanjiadian Formation, there is no bit mud-packing phenomenon. When drilling directionally in the Hanjiadian Formation and the Xiaoheba Formation, the downhole friction is normal, there is no pipe sticking phenomenon, and the friction during tripping with the anti-foaming lubricant is 20-30 tons. The mechanical drilling speed is 20% higher than that of Well Shengye 14-2.

[0097] The potassium chloride polymer drilling fluid used in Well Shengye 14-8 is different from the potassium chloride polymer drilling fluid used in Well Shengye 14-2 in that lubricant J is replaced by lubricant D; during the drilling process, there is no foam on the drilling fluid; when drilling through the strongly water-sensitive formation of the Hanjiadian Formation, there is no bit balling phenomenon. When drilling directionally in the Hanjiadian Formation and the Xiaoheba Formation, the downhole friction is normal and there is no string sticking phenomenon. When using the anti-foam lubricant, the friction during tripping is 20 - 30 tons, and the mechanical drilling rate is increased by 20% compared to Well Shengye 14-2.

[0098] The potassium chloride polymer drilling fluid used in Well Shengye 14-9 is different from the potassium chloride polymer drilling fluid used in Well Shengye 14-2 in that lubricant J is replaced by lubricant C; during the drilling process, there is no foam on the drilling fluid; when drilling through the strongly water-sensitive formation of the Hanjiadian Formation, there is no bit balling phenomenon. When drilling directionally in the Hanjiadian Formation and the Xiaoheba Formation, the downhole friction is normal and there is no string sticking phenomenon. When using the anti-foam lubricant, the friction during tripping is 15 - 20 tons, and the mechanical drilling rate is increased by 30% compared to Well Shengye 14-2.

[0099] The potassium chloride polymer drilling fluid used in Well Shengye 14-10 is different from the potassium chloride polymer drilling fluid used in Well Shengye 14-2 in that lubricant J is replaced by lubricant B; during the drilling process, there is no foam on the drilling fluid; when drilling through the strongly water-sensitive formation of the Hanjiadian Formation, there is no bit balling phenomenon. When drilling directionally in the Hanjiadian Formation and the Xiaoheba Formation, the downhole friction is normal and there is no string sticking phenomenon. When using the anti-foam lubricant, the friction during tripping is 15 - 20 tons, and the mechanical drilling rate is increased by 30% compared to Well Shengye 14-2.

[0100] The potassium chloride polymer drilling fluid used in Well Shengye 14-11 is different from the potassium chloride polymer drilling fluid used in Well Shengye 14-2 in that lubricant J is replaced by lubricant A; during the drilling process, there is no foam on the drilling fluid; when drilling through the strongly water-sensitive formation of the Hanjiadian Formation, there is no bit balling phenomenon. When drilling directionally in the Hanjiadian Formation and the Xiaoheba Formation, the downhole friction is normal and there is no string sticking phenomenon. When using the anti-foam lubricant, the friction during tripping is 15 - 20 tons, and the mechanical drilling rate is increased by 30% compared to Well Shengye 14-2.

[0101] From the above results, it can be seen that using the lubricant of the present invention for drilling has the effects of being not easy to foam and having good lubrication effect.

[0102] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A lubricant, characterized in that, The lubricant includes a base oil, an emulsifier, and an antioxidant. Among them, the base oil includes gas-made oil and / or petroleum hydrotreated light fraction; The emulsifier includes a polyether with a structural unit content of 5% to 15 wt% from ethylene oxide and a structural unit content of 85% to 95 wt% from propylene oxide, and the number-average molecular weight of the emulsifier is 1600 to 2300 g·mol -1 ; the antioxidant is alkylated diphenylamine; Based on 100 parts by volume of the lubricant, the lubricant includes: base oil, 70 - 90 parts; emulsifier, 10 - 30 parts; antioxidant, 0.2 - 0.5 part.

2. The lubricant according to claim 1, wherein The flash point of the base oil is above 80°C, and the aromatic hydrocarbon content is above 500 mg / kg.

3. The lubricant according to claim 2, wherein The biodegradation rate of the base oil in seawater within 28 days is above 70%.

4. The lubricant according to claim 1, wherein, The thermal decomposition temperature of the emulsifier is above 250°C, and the cloud point is 20 - 30°C.

5. The lubricant according to claim 1, wherein, The alkylated diphenylamine is a reaction product of the alkylation of diisobutene and diphenylamine.

6. The lubricant according to any one of claims 1-5, wherein, The reduction rate of the extreme pressure lubrication coefficient of the lubricant is not less than 98.5%.

7. A method for preparing the lubricant according to any one of claims 1-6, characterized in that, The method includes: a. First, mix the base oil and the antioxidant to prepare a blend; b. Second, mix the blend and the emulsifier to prepare the lubricant.

8. The preparation method according to claim 7, wherein, The conditions for the first mixing include: the stirring speed is 5000 - 15000 r / min, and the stirring time is 5 - 20 min.

9. The preparation method according to claim 7, wherein, The conditions for the second mixing include: the stirring speed is 5000 - 15000 r / min, and the stirring time is 5 - 20 min.

10. Application of the lubricant according to any one of claims 1 - 6 in the technical field of petroleum drilling engineering.

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