A high temperature and high salt resistant oilfield lubricant

Abstract

The invention belongs to the technical field of oil and gas field chemistry, and specifically discloses an oil field lubricant resistant to high temperature and high salt. The oil field lubricant provided by the invention comprises the following components: fatty alcohol polyoxypropylene ether SPO-3079%-83%, C23-43 acid pentaerythritol tetraester 10%-13%, bisphenol A phosphite ester 3%-5%, L-61 type propylene glycol block polyether 1%, North American rock asphalt powder 2%-3%, and the sum of the above components is 100%. The oil field lubricant has the advantages of resistance to 210°C high temperature and salt, good lubricity, wide applicability, good long-term lubrication, etc.

Description

Technical Field

[0001] The invention belongs to the technical field of oil and gas field chemistry, and in particular relates to an oil field lubricant resistant to high temperature and high salt. Background Art

[0002] Lubricants need to be added to the drilling fluid to reduce the flow resistance of the drilling fluid and the friction coefficient of the filter cake, reduce the torque of the drill bit and increase its water horsepower to improve the drilling efficiency. As offshore oil drilling develops from shallow water to deep water and ultra-deep water, the number of high-temperature, high-pressure, large-displacement wells and horizontal wells drilled at sea is increasing. Offshore drilling projects are facing complex downhole conditions such as pressure support caused by high temperature, high pressure, high salt and high friction, resistance to drilling and casing, etc., which greatly increases the difficulty of operation and drilling costs. Under ultra-high temperature and high salt conditions of 210℃, most lubricants will have a significant decrease in lubricant performance, and some will even deteriorate and lack stability, which cannot meet the drilling lubrication needs of ultra-deep marine wells. Summary of the invention

[0003] In view of the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a high-stability, high-temperature and high-salt resistant oilfield lubricant and a preparation method thereof. The oilfield lubricant has the advantages of 210°C high temperature and salt resistance, good lubricity, wide applicability, and good long-term lubrication.

[0004] In order to achieve the above object, the present invention adopts the following technical scheme:

[0005] A high temperature and high salt resistant oilfield lubricant comprises the following components: 79%-83% of fatty alcohol polyoxypropylene ether SPO-30, 10%-13% of C23-43 acid pentaerythritol tetraester, 3%-5% of bisphenol A phosphite, 1% of L-61 type propylene glycol block polyether, 2%-3% of North American rock asphalt powder, and the total of the above components is 100%.

[0006] A method for preparing a high temperature and high salt resistant oilfield lubricant comprises the following steps: weighing raw materials according to a ratio, stirring and mixing fatty alcohol polyoxypropylene ether SPO-30, C23-43 acid pentaerythritol tetraester, bisphenol A phosphite, L-61 type propylene glycol block polyether and North American rock asphalt powder to obtain a high temperature and high salt resistant oilfield lubricant. More specifically, the method comprises the following steps:

[0007] Step 1: weigh the raw materials according to the ratio, add the fatty alcohol polyoxypropylene ether SPO-30 into the reactor, start stirring at a speed of 90r-130r / min, add C23-43 acid pentaerythritol tetraester, stir for 0.5h-1.0h to obtain a uniform light yellow transparent liquid, and then start heating;

[0008] Step 2: When the temperature rises to 45-50°C, add bisphenol A phosphite and L-61 propylene glycol block polyether into the reactor, maintain the temperature at 45-50°C and stir it for 0.5h, then reduce the stirring speed to 40r-60r / min and add North American rock asphalt powder, stir it slowly for 1.0-1.5h, and then cool it to room temperature to obtain a brown-black liquid, which is an oilfield lubricant resistant to high temperature and high salt.

[0009] The above-mentioned high temperature and high salt resistant oilfield lubricant is used in deepwater and ultra-deepwater oil and gas field drilling with a temperature not higher than 210° C. The addition amount of the above-mentioned high temperature and high salt resistant oilfield lubricant is 0.5%-3.0%.

[0010] The functions of the components in the high-temperature and high-salt resistant oilfield lubricant of the present invention are as follows: fatty alcohol polyoxypropylene ether SPO-30 is used as a base oil component, L-61 type propylene glycol block polyether has a similar structure to the base oil component and good compatibility, is mainly used as a high-temperature defoamer, also has certain lubricity and can withstand high temperatures; bisphenol A phosphite is a phosphorus-containing rigid structure, has good thermal stability and oxidation resistance, and mainly functions to improve high-temperature salt resistance and wear resistance; North American rock asphalt powder is a powder of North American rock asphalt with a high softening point, has a softening point of 190-204 DEG C, and an asphaltene content of not less than 76%, and is mainly used as an extreme pressure additive and a temperature resistance enhancer; North American rock asphalt and bisphenol A phosphite have synergistic synergistic effects, and have a benefit effect on high-temperature lubrication stability from different aspects, and the lack of either of the two will cause the high-temperature lubrication performance of the obtained lubricant sample to decrease significantly; C23-43 acid pentaerythritol tetraester has a longer hydrocarbon chain, a higher boiling point and better high-temperature stability, and can be used as an enhancer component to improve high-temperature lubricity within a certain range.

[0011] It is precisely because of the adoption of the above scheme that the oilfield lubricant of the present invention has four major advantages: temperature and salt resistance, good lubricity, wide applicability, and good long-term lubrication. This application is mainly designed for lubrication in high-temperature and high-salt oilfields and can be dispersed in water; it can resist temperatures up to 210°C and can be used in almost all oilfield systems such as fresh water, seawater and salt water to reduce the lubrication coefficient and torque; when added to drilling fluid in a high-temperature and high-salt environment, it has almost no negative impact on the rheology and filtration performance of the drilling fluid; it can form a relatively strong extreme pressure lubrication film on the surface of metal drilling tools, and has the effect of long-term lubrication. DETAILED DESCRIPTION

[0012] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0013] The present invention provides a technical solution: a high temperature and high salt resistant drilling fluid lubricant.

[0014] Among the raw materials used, North American rock asphalt powder was purchased from Qingdao Meilian Energy Co., Ltd., with a 200-mesh sieve residue of ≤10% and an asphaltene content of 76%-78%.

[0015] Embodiment 1:

[0016] The lubricant is composed of the following components: 79 kg of fatty alcohol polyoxypropylene ether SPO-30, 13 kg of C23-43 acid pentaerythritol tetraester, 5 kg of bisphenol A phosphite, 1 kg of L-61 type propylene glycol block polyether, and 2 kg of North American rock asphalt powder. The total weight of the above components is 100 kg, and the lubricant is obtained by the following method:

[0017] The raw materials were weighed according to the ratio, 79 kg of fatty alcohol polyoxypropylene ether SPO-30 was added into the reactor, stirring was started at a speed of 120 r / min, 13 kg of C23-43 acid pentaerythritol tetraester was added, and stirring was carried out for 0.5 h to obtain a uniform light yellow transparent liquid, and then the temperature was increased; when the temperature rose to 45°C, 5 kg of bisphenol A phosphite and 1 kg of L-61 type propylene glycol block polyether were added to the reactor in succession, the temperature was maintained at 45-50°C and stirred for 0.5 h, and then the stirring speed was reduced to 50 r / min and 2 kg of North American rock asphalt powder was added, and it was stirred slowly for 1.5 h, and then the brown-black liquid obtained by cooling to room temperature was the high temperature and high salt resistance drilling fluid lubricant sample.

[0018] Afterwards, the performance test of the samples was carried out, and each embodiment was carried out according to the following test method:

[0019] With reference to "SY / T 6094-94 Evaluation Procedure for Lubricants for Drilling Fluids", the torque reduction rate and lubrication coefficient reduction rate of the lubricant sample of Example 1 were tested in fresh water, artificial seawater, and salt water drilling fluid systems before and after hot rolling at 210°C for 16 hours, wherein the fresh water slurry was 6% bentonite slurry, the artificial seawater slurry was prepared by stirring distilled water, bentonite, and artificial seawater in a mass ratio of 75:9:50, and the salt water slurry was prepared by stirring distilled water, bentonite, and sodium chloride in a mass ratio of 100:6:15. The lubricant sample of Example 1 was added in an amount of 1.0% in each experimental slurry, and the blank control group experimental slurry was not added with the lubricant sample of Example 1, and the compatibility of the experimental slurries with the lubricant sample added was observed.

[0020] The torque reduction rate, lubrication coefficient reduction rate and compatibility performance index of the lubricant sample obtained in Example 1 in three experimental slurries are tested as shown in Table 1-1:

[0021] Table 1-1

[0022]

[0023]

[0024] Freshwater bentonite slurry and saltwater bentonite slurry to which the lubricant sample of Example 1 was added were tested for basic drilling fluid mud indicators such as density (ρ), apparent viscosity (AV), plastic viscosity (PV), and dynamic shear force (YP) according to ISO10414-2 (API 13B-2) standard.

[0025] Example 1 The basic index test data of the freshwater drilling fluid sample are as follows Table 1-2

[0026] Table 1-2

[0027]

[0028] Example 1 The basic index test data of the sample salt water drilling fluid mud are as follows Table 1-3

[0029] Table 1-3

[0030]

[0031]

[0032] Compared with the 6% bentonite freshwater base slurry, the density of the bentonite slurry before 210℃ hot rolling with the lubricant sample of Example 1 decreased, while the viscosity value increased, and the API filtration loss was reduced; compared with the freshwater slurry before hot rolling with the lubricant sample of Example 1, the density of the bentonite slurry after 210℃ hot rolling decreased, the API filtration loss increased, and the viscosity value decreased, and the density change value and the apparent viscosity change value both met the basic requirements for the use of mud lubricants. Compared with the salt water bentonite base slurry, the density of the salt water bentonite slurry before 210℃ hot rolling with the lubricant sample of Example 1 decreased, the API filtration loss was reduced, and the viscosity value increased; compared with the salt water slurry before hot rolling with the lubricant sample of Example 1, the density of the salt water bentonite slurry after 210℃ hot rolling decreased, the API filtration loss increased significantly but was still lower than the filtration loss of the salt water base slurry before hot rolling, and the viscosity value decreased, and the filtration loss, density and apparent viscosity change values ​​all met the basic requirements for the use of mud lubricants. This sample has good compatibility in both fresh water slurry and salt water slurry.

[0033] Embodiment 2:

[0034] The lubricant is composed of the following components: 3 kg of fatty alcohol polyoxypropylene ether SPO-308, 10 kg of C23-43 acid pentaerythritol tetraester, 3 kg of bisphenol A phosphite, 1 kg of L-61 type propylene glycol block polyether, and 3 kg of North American rock asphalt powder. The total weight of the above components is 100 kg, and the lubricant is obtained by the following method:

[0035] The raw materials were weighed according to the ratio, 83 kg of fatty alcohol polyoxypropylene ether SPO-30 was added into the reactor, stirring was started at a speed of 120 r / min, 10 kg of C23-43 acid pentaerythritol tetraester was added, and stirring was carried out for 0.5 h to obtain a uniform light yellow transparent liquid, and then the temperature was increased; when the temperature rose to 45°C, 3 kg of bisphenol A phosphite and 1 kg of L-61 type propylene glycol block polyether were added to the reactor in succession, and the temperature was maintained at 45-50°C and stirred for 0.5 h, and then the stirring speed was reduced to 50 r / min and 3 kg of North American rock asphalt powder was added, and it was stirred slowly for 1.5 h, and then the brown-black liquid obtained by cooling to room temperature was the high temperature and high salt resistance drilling fluid lubricant sample.

[0036] The torque reduction rate, lubrication coefficient reduction rate and compatibility performance index of the lubricant sample obtained in Example 2 in the experimental slurry are tested as shown in Table 2:

[0037] Table 2

[0038]

[0039] Embodiment three:

[0040] The lubricant is composed of the following components: 80 kg of fatty alcohol polyoxypropylene ether SPO-30, 12 kg of C23-43 acid pentaerythritol tetraester, 4 kg of bisphenol A phosphite, 1 kg of L-61 type propylene glycol block polyether, and 3 kg of North American rock asphalt powder. The total weight of the above components is 100 kg, and the lubricant is obtained by the following method:

[0041] The raw materials were weighed according to the ratio, 80 kg of fatty alcohol polyoxypropylene ether SPO-30 was added into the reactor, stirring was started at a speed of 120 r / min, 12 kg of C23-43 acid pentaerythritol tetraester was added, and stirring was carried out for 0.5 h to obtain a uniform light yellow transparent liquid, and then the temperature was increased; when the temperature rose to 45°C, 4 kg of bisphenol A phosphite and 1 kg of L-61 propylene glycol block polyether were added to the reactor in succession, the temperature was maintained at 45-50°C and stirred for 0.5 h, and then the stirring speed was reduced to 50 r / min and 3 kg of North American rock asphalt powder was added, and it was stirred slowly for 1.5 h, and then the brown-black liquid obtained by cooling to room temperature was the high temperature and high salt resistance drilling fluid lubricant sample.

[0042] The torque reduction rate, lubrication coefficient reduction rate and compatibility performance index of the lubricant sample obtained in Example 3 are tested in the following Table 3:

[0043] Table 3

[0044]

[0045]

[0046] Embodiment 4:

[0047] The lubricant is composed of the following components: 80 kg of fatty alcohol polyoxypropylene ether SPO-30, 4 kg of bisphenol A phosphite, 1 kg of L-61 propylene glycol block polyether, and 3 kg of North American rock asphalt powder. The total weight of the above components is 88 kg, and the lubricant is obtained by the following method:

[0048] Weigh the raw materials according to the ratio, add 80kg of fatty alcohol polyoxypropylene ether SPO-30 into the reactor, start stirring at a speed of 120r / min, and start heating; when the temperature rises to 45°C, add 4kg of bisphenol A phosphite and 1kg of L-61 propylene glycol block polyether into the reactor, maintain the temperature at 45-50°C and stir for 0.5h, then reduce the stirring speed to 50r / min and add 3kg of North American rock asphalt powder, stir it slowly for 1.5h, and then cool it to room temperature to obtain a brown-black liquid, which is the lubricant sample.

[0049] The torque reduction rate, lubrication coefficient reduction rate and compatibility performance index of the lubricant sample obtained in Example 4 are tested in the following Table 4:

[0050] Table 4

[0051]

[0052]

[0053] Compared with Example 3, the lubricant sample prepared in Example 4 does not contain C23-43 acid pentaerythritol tetraester component, resulting in reduced lubrication performance, especially under high temperature conditions of 210° C. It is speculated that the four ester groups in C23-43 acid pentaerythritol tetraester are concentrated on the metal surface, and the adsorption force is strong. At the same time, the long hydrocarbon chains on the four sides of the molecule provide good high-temperature lubrication performance. C23-43 acid pentaerythritol tetraester has good compatibility with other components of the lubricant of the present invention, so it can improve the high-temperature lubricity of the lubricant of the present invention.

[0054] Embodiment five:

[0055] The lubricant is composed of the following components: 80 kg of fatty alcohol polyoxypropylene ether SPO-30, 12 kg of pentaerythritol oleate, 4 kg of bisphenol A phosphite, 1 kg of L-61 type propylene glycol block polyether, and 3 kg of North American rock asphalt powder. The total weight of the above components is 100 kg, and the lubricant is obtained by the following method:

[0056] Weigh the raw materials according to the ratio, add 80kg of fatty alcohol polyoxypropylene ether SPO-30 into the reactor, start stirring at a speed of 120r / min, add 12kg of pentaerythritol oleate, stir for 0.5h, obtain a uniform light yellow transparent liquid, and then start heating; when the temperature rises to 45°C, add 4kg of bisphenol A phosphite and 1kg of L-61 propylene glycol block polyether into the reactor in succession, maintain the temperature at 45-50°C and stir for 0.5h, then reduce the stirring speed to 50r / min and add 3kg of North American rock asphalt powder, stir it slowly for 1.5h, and then cool it to room temperature to obtain a brown-black liquid, which is the lubricant sample.

[0057] The torque reduction rate, lubrication coefficient reduction rate and compatibility performance index of the lubricant sample obtained in Example 5 are tested in the following Table 5:

[0058] Table 5

[0059]

[0060] Compared with Example 3, the lubricant sample prepared in Example 5 uses pentaerythritol oleate to replace C23-43 acid pentaerythritol tetraester, but compared with the results of Example 4 without adding any pentaerythritol ester, it can be seen that pentaerythritol oleate has little effect on the lubricant, and overall it can slightly improve the high-temperature lubrication performance of the lubricant but also slightly reduce the room-temperature lubrication performance of the lubricant. In comparison, C23-43 acid pentaerythritol tetraester has a more obvious benefit on the high-temperature lubrication performance of the lubricant of the present invention. It is speculated that the reason is that the hydrocarbon chain in the C23-43 acid pentaerythritol tetraester molecule is longer, the boiling point is higher, and the high-temperature stability is better.

[0061] Embodiment six:

[0062] The lubricant is composed of the following components: 79 kg of fatty alcohol polyoxypropylene ether SPO-30, 13 kg of C23-43 acid pentaerythritol tetraester, 5 kg of bisphenol A phosphite, and 2 kg of North American rock asphalt powder. The total weight of the above components is 99 kg, and the lubricant is obtained by the following method:

[0063] Weigh the raw materials according to the ratio, add 79kg of fatty alcohol polyoxypropylene ether SPO-30 into the reactor, start stirring at a speed of 120r / min, add 13kg of C23-43 acid pentaerythritol tetraester, stir for 0.5h, obtain a uniform light yellow transparent liquid, and then start heating; when the temperature rises to 45°C, add 5kg of bisphenol A phosphite into the reactor, maintain the temperature at 45-50°C and stir for 0.5h, then reduce the stirring speed to 50r / min and add 2kg of North American rock asphalt powder, stir it slowly for 1.5h, and then cool it to room temperature to obtain a brown-black liquid, which is the lubricant sample.

[0064] The torque reduction rate, lubrication coefficient reduction rate and compatibility performance index of the lubricant sample obtained in Example 6 are tested in the following Table 6:

[0065] Table 6

[0066]

[0067]

[0068] Compared with Example 1, the lubricant sample prepared in Example 6 does not contain the L-61 propylene glycol block polyether defoamer component, resulting in only a slight decrease in lubrication performance, but the compatibility with drilling fluid mud is more obvious, especially after hot rolling at 210°C. This is because the mud system has a high foaming amount, which causes partial instability and imbalance of the system, and the surface tension is reduced in a high temperature environment, making the mud more likely to foam, so the lubricant of the present invention must be added with a defoamer component.

[0069] Embodiment seven:

[0070] The lubricant is composed of the following components: 80 kg of fatty alcohol polyoxypropylene ether SPO-20, 12 kg of C23-43 acid pentaerythritol tetraester, 4 kg of bisphenol A phosphite, 1 kg of L-61 type propylene glycol block polyether, and 3 kg of North American rock asphalt powder. The total weight of the above components is 100 kg, and the lubricant is obtained by the following method:

[0071] Weigh the raw materials according to the ratio, add 80kg of fatty alcohol polyoxypropylene ether SPO-20 into the reactor, start stirring at a speed of 120r / min, add 12kg of C23-43 acid pentaerythritol tetraester, stir for 0.5h, obtain a uniform light yellow transparent liquid, and then start heating; when the temperature rises to 45°C, add 4kg of bisphenol A phosphite and 1kg of L-61 propylene glycol block polyether into the reactor in turn, maintain the temperature at 45-50°C and stir for 0.5h, then reduce the stirring speed to 50r / min and add 3kg of North American rock asphalt powder, stir it slowly for 1.5h, and then cool it to room temperature to obtain a brown-black liquid, which is the lubricant sample.

[0072] The torque reduction rate, lubrication coefficient reduction rate and compatibility performance index of the lubricant sample obtained in Example 7 are tested in the following Table 7:

[0073] Table 7

[0074]

[0075] Example 7 is the control group of Example 3. In the lubricant sample prepared in Example 7, the base oil is replaced from fatty alcohol polyoxypropylene ether SPO-30 to SPO-20. Compared with the results of Example 3, it can be seen that the torque reduction performance of the lubricant sample prepared with SPO-20 is significantly reduced (so the lubrication coefficient reduction rate is no longer tested), especially in the mud system after hot rolling at 210°C, it cannot meet the use requirements of the 210°C high temperature oil well environment.

[0076] Embodiment eight:

[0077] The lubricant sample is prepared by mixing and compounding 99 kg of fatty alcohol polyoxypropylene ether SPO-30 and 1 kg of L-61 propylene glycol block polyether. Specifically, the raw materials are weighed according to the ratio, 99 kg of fatty alcohol polyoxypropylene ether SPO-30 is added into the reactor, stirring is started at a speed of 120 r / min, 1 kg of L-61 propylene glycol block polyether is added, and stirring is carried out for 0.5 h to obtain a colorless and slightly yellow liquid, which is the lubricant sample.

[0078] Since the performance test results of the lubricant sample of Example 8 after hot rolling at 210°C were poor, the lubrication performance of the sample after hot rolling at 200°C was also tested.

[0079] Example 8 The torque reduction rate, lubrication coefficient reduction rate and compatibility performance index test of the lubricant sample in the experimental slurry are shown in Table 8:

[0080] Table 8

[0081]

[0082]

[0083] From the data, we can see that the base oil fatty alcohol polyoxypropylene ether SPO-30 in the lubricant raw material component of the present invention has poor lubrication performance under the condition of hot rolling at 210°C, and the data under the condition of hot rolling at 200°C is also relatively general and can only barely meet the use requirements. This shows that the base oil in the lubricant raw material component of the present invention will significantly reduce its high-temperature lubricity above 200°C without adding other auxiliary agents and enhancer components.

[0084] Embodiment nine:

[0085] The lubricant is composed of the following components: 80 kg of fatty alcohol polyoxypropylene ether SPO-30, 12 kg of C23-43 acid pentaerythritol tetraester, 1 kg of L-61 type propylene glycol block polyether, and 3 kg of North American rock asphalt powder. The total weight of the above components is 96 kg, and the lubricant is obtained by the following method:

[0086] Weigh the raw materials according to the ratio, add 80kg of fatty alcohol polyoxypropylene ether SPO-30 into the reactor, start stirring at a speed of 120r / min, add 12kg of C23-43 acid pentaerythritol tetraester, stir for 0.5h, obtain a uniform light yellow transparent liquid, and then start heating; when the temperature rises to 45°C, add 1kg of L-61 type propylene glycol block polyether into the reactor, maintain the temperature at 45-50°C and stir for 0.5h, then reduce the stirring speed to 50r / min and add 3kg of North American rock asphalt powder, stir it slowly for 1.5h, and then cool it to room temperature to obtain a brown-black liquid, which is the lubricant sample.

[0087] The torque reduction rate, lubrication coefficient reduction rate and compatibility performance index of the lubricant sample obtained in Example 9 in the experimental slurry are tested as shown in Table 9:

[0088] Table 9

[0089]

[0090]

[0091] Compared with Example 3, the bisphenol A phosphite component was not added to the lubricant sample prepared in Example 9, resulting in the lubrication performance data of the freshwater bentonite slurry not changing much or even slightly increasing under normal temperature conditions before hot rolling, and the lubrication performance in the salt water slurry and seawater slurry decreased slightly; but after hot rolling at 210°C, the lubrication performance data of the freshwater bentonite slurry decreased, while the lubrication performance data in the salt water slurry and seawater slurry decreased to a greater extent, which shows that the raw material of bisphenol A phosphite can enhance the temperature and salt resistance of the lubricant of the present application. It is speculated that it may be because bisphenol A phosphite itself is a rigid structure containing phosphorus, and the combination with the lubricating component of the present invention can improve the wear resistance and high temperature stability of the present application.

[0092] Embodiment ten:

[0093] The lubricant is composed of the following components: 80 kg of fatty alcohol polyoxypropylene ether SPO-30, 12 kg of C23-43 acid pentaerythritol tetraester, 4 kg of bisphenol A phosphite, and 1 kg of L-61 type propylene glycol block polyether. The total weight of the above components is 97 kg. It is obtained by the following method:

[0094] The raw materials were weighed according to the ratio, 80 kg of fatty alcohol polyoxypropylene ether SPO-30 was added into the reactor, stirring was started at a speed of 120 r / min, 12 kg of C23-43 acid pentaerythritol tetraester was added, and stirring was carried out for 0.5 h to obtain a uniform light yellow transparent liquid, and then the temperature was increased; when the temperature rose to 45°C, 4 kg of bisphenol A phosphite and 1 kg of L-61 propylene glycol block polyether were added to the reactor in succession, the temperature was maintained at 45-50°C and stirred for 0.5 h, and the light yellow liquid obtained by cooling to room temperature was the lubricant sample.

[0095] The torque reduction rate, lubrication coefficient reduction rate and compatibility performance index of the lubricant sample obtained in Example 10 are tested in the following Table 10:

[0096] Table 10

[0097]

[0098]

[0099] Compared with Example 3, the lubricant sample prepared by implementing the tenth method did not add the North American rock asphalt component, resulting in a significant decrease in the high-temperature lubrication performance at 210°C, which was the case for freshwater slurry, seawater slurry, and salt water slurry. It is speculated that on the one hand, the elements S, N, etc. in the North American rock asphalt molecules can improve the extreme pressure of the lubricant of the present application, and on the other hand, compared with the general oily lubricant component, the North American rock asphalt molecules are more "thick" and have lower mobility and stronger stability under high temperature conditions of 210°C. Moreover, North American rock asphalt and bisphenol A phosphite embody the synergistic enhancement of 1+1>2 in the application. In the present invention, the lack of either of them will cause the high-temperature lubrication performance of the obtained lubricant sample to decrease significantly. This may be because these two substances have a benefit effect on the high-temperature lubrication stability of the present application from different aspects, making up for the shortcomings.

[0100] The above description of the embodiments is to facilitate the understanding and use of the present invention by those of ordinary skill in the art. It is obvious that those familiar with the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments. Improvements and modifications made by those skilled in the art based on the principles of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention. The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A high temperature and high salt resistant oilfield lubricant, characterized in that: The invention comprises the following components: 79%-83% of fatty alcohol polyoxypropylene ether SPO-30, 10%-13% of C23-43 acid pentaerythritol tetraester, 3%-5% of bisphenol A phosphite, 1% of L-61 type propylene glycol block polyether, 2%-3% of North American rock asphalt powder, and the total of the above components is 100%.

2. The high temperature and high salt resistant oilfield lubricant according to claim 1, characterized in that: The softening point of the North American rock asphalt powder is 190-204° C., and the asphaltene content is not less than 76%.

3. The high temperature and high salt resistant oilfield lubricant according to claim 1, characterized in that: The particle size of the North American rock asphalt powder is ≤10% when passing through a 200-mesh sieve.

4. The method for preparing the high temperature and high salt resistant oilfield lubricant according to any one of claims 1 to 3, characterized in that: The steps include: Step 1: weigh the raw materials according to the ratio, add the fatty alcohol polyoxypropylene ether SPO-30 into the reactor, start stirring at a speed of 90r-130r / min, add C23-43 acid pentaerythritol tetraester, stir for 0.5h-1.0h to obtain a uniform light yellow transparent liquid, and then start heating; Step 2: When the temperature rises to 45-50°C, add bisphenol A phosphite and L-61 propylene glycol block polyether into the reactor, maintain the temperature at 45-50°C and stir it for 0.5h, then reduce the stirring speed to 40r-60r / min and add North American rock asphalt powder, stir it slowly for 1.0-1.5h, and then cool it to room temperature to obtain a brown-black liquid, which is an oilfield lubricant resistant to high temperature and high salt.

5. Use of the high temperature and high salt resistant oilfield lubricant according to any one of claims 1 to 3 or the high temperature and high salt resistant oilfield lubricant prepared by the method according to claim 4 in deepwater and ultra-deepwater oil and gas field drilling at a temperature not higher than 210°C.

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