Environment-friendly lubricant for drilling fluid and preparation method thereof

Abstract

This invention relates to an environmentally friendly lubricant for drilling fluids and its preparation method, comprising the following components by volume percentage: base oil: 50-70 vol 1%; polysorbate-80: 5-12 vol 1%; water: 15-30 vol 1%; defoamer: 1-3 vol 1%; surfactant: 5-16 vol 1%; alkalinity regulator: 0.5-1.0 vol 1%; nano-graphite powder: 2-6 vol 1%; glass microspheres: 1-3 vol 1%. The above components are uniformly dispersed by stepwise ultrasonic stirring. The preparation process of this invention is simple, and the resulting lubricant possesses excellent lubricity, anti-wear properties, temperature resistance, high-temperature stability, strength, and distribution.

Description

Technical Field

[0001] This invention belongs to the field of lubricant technology, specifically relating to an environmentally friendly lubricant for drilling fluids and its preparation method. Background Technology

[0002] With the rapid development of industry, oilfield exploration and development are constantly deepening. During the drilling process, drilling fluid can reduce the torque and frictional resistance of the drill string, reduce drill string wear, and extend the service life of drill bit bearings. Lubricity is an important indicator of drilling fluid performance. By adding drilling fluid lubricants, the lubrication performance of the drilling fluid can be effectively improved, reducing drill string torque, reducing wear on the drill string, protecting the drill string, and reducing the occurrence of downhole accidents.

[0003] Currently, most drilling fluid lubricants used in drilling use mineral oil as the main raw material. These types of drilling fluid lubricants have low lubrication performance and are not easily biodegradable, causing environmental pollution and increasing the difficulty of waste fluid treatment. Alternatively, they use recycled waste oil such as swill oil as raw materials. These recycled oils contain environmentally harmful substances and have complex chemical treatment processes.

[0004] CN 118272058 A discloses a drilling fluid lubricant and its preparation method, relating to the field of lubricant technology. The drilling fluid lubricant is made from the following components: 2-10 wt% nano-graphite powder, 5-10 wt% emulsifier, 5-8 wt% defoamer, 15-20 wt% wetting agent, 0.5-1.0 wt% alkalinity adjuster, and 50-73 wt% base oil. While using modified vegetable oil as the base oil facilitates biodegradability and improves temperature and salt resistance, this type of vegetable oil, after epoxy modification, exhibits poor stability due to the ease with which the epoxy groups react with active hydrogen under acidic or alkaline conditions to undergo ring-opening reactions. Furthermore, while using octanol polyoxyethylene ether or alkylphenol polyoxyethylene ether as the emulsifier, or a 1:1 mass ratio of both, improves lubrication and drag reduction capabilities to some extent, it also suffers from poor temperature resistance. Summary of the Invention

[0005] The purpose of this invention is to solve the above-mentioned technical problems and provide an environmentally friendly lubricant for drilling fluids that has good lubricity, wear resistance, temperature resistance and high temperature stability, as well as good strength and distribution.

[0006] The present invention also provides a method for preparing the above-mentioned environmentally friendly lubricant for drilling fluid that is extremely simple in process and low in cost.

[0007] The environmentally friendly lubricant for drilling fluids of this invention comprises the following components by volume percentage:

[0008] Base oil: 50-75 vol;

[0009] Polysorbate-80: 5-12 vol 1%;

[0010] Water: 23-35 vol%;

[0011] Defoamer: 1-3 vol 1%;

[0012] Surfactant component: 5-16 vol;

[0013] Alkalinity adjuster: 0.5–1.0 vol;

[0014] Nano-graphite powder: 2-6 vol;

[0015] Glass microspheres: 1-3 vol 1%.

[0016] The base oil is a modified vegetable oil that has undergone epoxidation or sulfonation modification.

[0017] The vegetable oil is at least one of castor oil, cottonseed oil, or soybean oil.

[0018] The nano-graphite powder is scaly graphite with a particle size of 300-1000 nm.

[0019] The glass microspheres are hollow quartz glass microspheres.

[0020] The hollow quartz glass microspheres have a particle size of 70-75 μm and a density of 1.25-1.30 g / cm³. 3 Hardness 6HB.

[0021] The defoamer is dimethyl silicone oil, and the alkalinity regulator is sodium hydroxide or potassium hydroxide.

[0022] The method for synthesizing the surface-active component is as follows:

[0023] Dissolve (E)-2-octadecenol in 95% ethanol solution to a mass concentration of 8wt%–10wt%, titrate with 0.5 mol / L sodium hydroxide using phenolphthalein as an indicator, and after reaching the equivalence point, dilute with water at a mass ratio of 1:30 to obtain solution A.

[0024] Sodium methylpropenesulfonate was dissolved in water to a concentration of 1 wt%–2 wt%, and the pH was adjusted to 8–9 to obtain solution B.

[0025] Solution A and solution B are mixed at a mass ratio of 8 to 10:1, and ammonium persulfate initiator is added dropwise. The mixture is stirred and reacted at 65 to 85°C. After the reaction is completed, the surface-active component is obtained by cooling to room temperature.

[0026] The initiator dosage is 3% of the total mass fraction of solution A and solution B, the stirring speed is 1000 r / min, and the stirring time is 6-7 h.

[0027] The method for preparing the environmentally friendly lubricant for drilling fluid includes the following steps:

[0028] S1: Pour the base oil, polysorbate-80, water, and defoamer into the reaction vessel, mix and ultrasonically stir to obtain a uniform emulsion;

[0029] S2: Add the surfactant component to the emulsion obtained in step S1, disperse it by ultrasonication and stir it evenly, then add the alkalinity regulator and stir it evenly by ultrasonication.

[0030] S3: Mix nano-graphite powder and glass microspheres with the emulsion obtained in step S2, and then ultrasonically disperse them evenly to obtain an environmentally friendly lubricant for drilling fluid.

[0031] To address the problems existing in the background technology, the inventors made the following improvements:

[0032] 1) The base oil is a modified vegetable oil that has undergone epoxidation or sulfonation modification to improve its temperature and salt resistance. Addressing the issue of poor stability in modified vegetable oils, the inventors used a special surface-active component. This surface-active component is prepared by reacting a solution of (E)-2-octadecenol and sodium methylpropene sulfonate to form a macromolecular compound with a unique three-dimensional network structure. This structure, linked by branches, exhibits good thermal stability. When mixed with the modified vegetable oil, it produces a complex chemical reaction, influencing the reactivity, polarity, phase state, and biological activity of the modified vegetable oil. This overcomes the problem of poor stability in modified vegetable oils, giving the lubricant excellent temperature resistance and stability. Furthermore, when used as an emulsifier in combination with the base oil, its compound, composed of both hydrophobic and hydrophilic groups, allows the oil to form a more uniformly dispersed emulsion. By reducing surface tension, it allows drilling fluid to more easily penetrate the tiny gaps in the drill bit and wellbore, providing a more uniform lubrication effect. Compared to ordinary emulsifiers, it has better compatibility and lubrication performance. Here, the amount of surfactant added is 5-16 vol-%, more preferably 6-12 vol-%. Too high a concentration will affect the stability of the lubricant and make it prone to high-temperature denaturation, while too low a concentration will result in insufficient emulsification, poor lubrication effect, or even stratification.

[0033] 2) The glass microspheres are preferably hollow quartz glass microspheres with a density of 1.25-1.30 g / cm³. 3Hollow quartz glass microspheres at this density meet both strength requirements and suspension requirements in drilling fluid, allowing for better distribution and preventing significant floating or sedimentation of the lubricant. The addition amount is 1-3 vol%. Too high an amount will increase the solid content in the lubricant, negatively impacting lubrication performance, while too low an amount will result in insufficient sliding contact between solids, failing to achieve the desired lubrication effect. The nano-graphite powder is scaly graphite, forming an anti-wear layer on the drill bit surface in a layered structure, thereby reducing frictional resistance and providing lubrication.

[0034] The environmentally friendly lubricant for drilling fluid of this invention has good lubricity and anti-wear properties, is easily biodegradable, has low biotoxicity, is environmentally friendly, and has excellent lubricity, anti-wear properties, temperature resistance and high temperature stability, strength and distribution. The preparation method is simple, low-cost and highly efficient. Detailed Implementation

[0035] In Examples 1-8 below, the glass microspheres are hollow glass microspheres with a particle size of 70-75 μm and a density of 1.25-1.30 g / cm³. 3 The hardness is 6HB; the vegetable oils in Examples 1-4 were modified by epoxidation, and the vegetable oils in Examples 5-8 were modified by sulfonation.

[0036] Example 1

[0037] S1: Dissolve 85g of (E)-2-octadecenol in 100g of 95% (volume percentage) ethanol solution, titrate with 0.5mol / L sodium hydroxide, using phenolphthalein as an indicator, and after reaching the equivalence point, dilute with 3420ml of water (volume ratio of 1:30) to obtain 3615g of solution A.

[0038] S2: Dissolve 55g of sodium methyl propylene sulfonate in 300g of water, add 0.5mol / L sodium hydroxide to adjust the pH to 8, and obtain 368g of solution B.

[0039] S3: Mix solution A with solution B, add 119g of ammonium persulfate, stir at 70-72℃ at a stirring speed of 1000r / min, react for 6h, and finally cool to room temperature to obtain the surface active component.

[0040] S4: 25ml modified castor oil, 20ml modified cottonseed oil, 5ml modified soybean oil, 6ml polysorbate-80, 30ml water, and 1.5ml defoamer are poured into a reaction vessel, mixed, and ultrasonically stirred for 1 hour to obtain a uniform emulsion.

[0041] S5: Add 7 ml of surfactant component to the emulsion obtained in step S4, disperse it by ultrasound and stir for 90 minutes, add 0.5 ml of alkalinity adjuster and stir by ultrasound for 30 minutes.

[0042] S6: Add 3ml of nano-graphite powder and 2ml of glass microspheres to the emulsion obtained in step S5, disperse by ultrasonication and stir for 90 minutes to obtain an environmentally friendly lubricant for drilling fluid.

[0043] Example 2

[0044] Repeat steps S1-S3 in Example 1

[0045] S4: 30 ml modified castor oil, 22 ml modified cottonseed oil, 12 ml polysorbate-80, 16 ml water, and 3 ml defoamer are poured into a reaction vessel, mixed, and ultrasonically stirred for 1 hour to obtain a uniform emulsion.

[0046] S5: Add 7 ml of surfactant component to the emulsion obtained in step S4, disperse it by ultrasonication and stir for 90 minutes, add 1 ml of alkalinity adjuster and stir by ultrasonication for 30 minutes.

[0047] S6: Add 6ml of nano-graphite powder and 3ml of glass microspheres to the emulsion obtained in step S5, disperse by ultrasonication and stir for 90 minutes to obtain an environmentally friendly lubricant for drilling fluid.

[0048] Example 3

[0049] Repeat steps S1-S3 in Example 1

[0050] S4: 25ml modified castor oil, 20ml modified cottonseed oil, 25ml modified soybean oil, 5ml polysorbate-80, 15ml water, and 1ml defoamer are poured into a reaction vessel, mixed, and ultrasonically stirred for 1 hour to obtain a uniform emulsion.

[0051] S5: Add 5 ml of surfactant component to the emulsion obtained in step S4, disperse it by ultrasound and stir for 90 minutes, add 0.8 ml of alkalinity adjuster and stir by ultrasound for 30 minutes.

[0052] S6: Add 2ml of nano-graphite powder and 0.2ml of glass microspheres to the emulsion obtained in step S5, disperse by ultrasonication, and stir for 90 minutes to obtain an environmentally friendly lubricant for drilling fluid.

[0053] Example 4

[0054] Repeat steps S1-S3 in Example 1

[0055] S4: 25 ml modified cottonseed oil, 35 ml modified soybean oil, 6 ml polysorbate-80, 11 ml water, and 2 ml defoamer are poured into a reaction vessel, mixed, and ultrasonically stirred for 1 hour to obtain a uniform emulsion.

[0056] S5: Add 16 ml of surfactant component to the emulsion obtained in step S4, disperse it by ultrasound and stir for 90 minutes, add 0.6 ml of alkalinity adjuster and stir by ultrasound for 30 minutes.

[0057] S6: Add 3.4 ml of nano-graphite powder and 1 ml of glass microspheres to the emulsion obtained in step S5, disperse by ultrasonication, and stir for 90 minutes to obtain an environmentally friendly lubricant for drilling fluid.

[0058] Example 5

[0059] S1: Dissolve 95g of (E)-2-octadecenol in 100g of 95% ethanol solution, titrate with 0.5mol / L sodium hydroxide solution, using phenolphthalein as an indicator, and after reaching the equivalence point, dilute with 3447ml of water (volume ratio of 1:30) to obtain 3653g of solution A.

[0060] S2: Dissolve 50g of sodium methyl allyl sulfonate in 350g of water, add 0.5mol / L sodium hydroxide to adjust the pH to 8, and obtain 405g of solution B.

[0061] S3: Mix solution A and solution B, add 121g of ammonium persulfate, stir at 75-80℃ at a stirring speed of 1000r / min, react for 6h, and finally cool to room temperature to obtain the surface active component.

[0062] S4: 10ml modified castor oil, 15ml modified cottonseed oil, 25ml modified soybean oil, 7ml polysorbate-80, 30ml water, and 1ml defoamer are poured into a reaction vessel, mixed, and ultrasonically stirred for 1 hour to obtain a uniform emulsion.

[0063] S5: Add 5 ml of surfactant component to the emulsion obtained in step S4, disperse it by ultrasound and stir for 90 minutes, add 1 ml of alkalinity adjuster and stir by ultrasound for 30 minutes.

[0064] S6: Add 5ml of nano-graphite powder and 1ml of glass microspheres to the emulsion obtained in step S5, disperse by ultrasonication, and stir for 90 minutes to obtain an environmentally friendly lubricant for drilling fluid.

[0065] Example 6

[0066] Repeat steps S1-S3 in Example 5

[0067] S4: 30 ml modified castor oil, 25 ml modified soybean oil, 12 ml polysorbate-80, 16 ml water, and 3 ml defoamer are poured into a reaction vessel, mixed, and ultrasonically stirred for 1 hour to obtain a uniform emulsion.

[0068] S5: Add 6 ml of surfactant component to the emulsion obtained in step S4, disperse it by ultrasonication and stir for 90 minutes, add 0.7 ml of alkalinity adjuster and stir by ultrasonication for 30 minutes.

[0069] S6: Add 6ml of nano-graphite powder and 1.3ml of glass microspheres to the emulsion obtained in step S5, disperse by ultrasonication and stir for 90 minutes to obtain an environmentally friendly lubricant for drilling fluid.

[0070] Example 7

[0071] Repeat steps S1-S3 in Example 5

[0072] S4: 34 ml modified cottonseed oil, 20 ml modified soybean oil, 6 ml polysorbate-80, 15 ml water, and 2 ml defoamer are poured into a reaction vessel, mixed, and ultrasonically stirred for 1 hour to obtain a uniform emulsion.

[0073] S5: Add 16 ml of surfactant component to the emulsion obtained in step S4, disperse it by ultrasonication and stir for 90 minutes, add 0.5 ml of alkalinity adjuster and stir by ultrasonication for 30 minutes.

[0074] S6: Add 3.5 ml of nano-graphite powder and 3 ml of glass microspheres to the emulsion obtained in step S5, disperse by ultrasonication and stir for 90 minutes to obtain an environmentally friendly lubricant for drilling fluid.

[0075] Example 8

[0076] Repeat steps S1-S3 in Example 5

[0077] S4: 50 ml modified castor oil, 20 ml modified cottonseed oil, 5 ml polysorbate-80, 15 ml water, and 1 ml defoamer are poured into a reaction vessel, mixed, and ultrasonically stirred for 1 hour to obtain a uniform emulsion.

[0078] S5: Add 5.5 ml of surfactant component to the emulsion obtained in step S4, disperse it by ultrasonication, stir for 90 minutes, add 0.5 ml of alkalinity adjuster, and stir by ultrasonication for 30 minutes.

[0079] S6: Add 2ml of nano-graphite powder and 1ml of glass microspheres to the emulsion obtained in step S5, disperse by ultrasonication, and stir for 90 minutes to obtain an environmentally friendly lubricant for drilling fluid.

[0080] Comparative Example 1

[0081] In Example 1, S5: Steps S1-S3 are cancelled. 7 ml of surfactant SP-80 is added to the emulsion obtained in step S4, and the mixture is ultrasonically dispersed and stirred for 90 minutes. 0.5 ml of alkalinity adjuster is added and ultrasonically stirred for 30 minutes.

[0082] The other steps are the same as in Example 1.

[0083] Comparative Example 2

[0084] In Example 5, S5: Steps S1-S3 are cancelled. 5 ml of surfactant nonylphenol polyoxyethylene is added to the emulsion obtained in step S4, and after ultrasonic dispersion, it is stirred for 90 minutes. Then, 1 ml of alkalinity adjuster is added and ultrasonically stirred for 30 minutes.

[0085] The other steps are the same as in Example 5.

[0086] Comparative Example 3

[0087] In Example 2, steps S5 and S6 involve adding 6 ml of nano-graphite powder and 3 ml of glass microspheres (conventional solid glass, density 2.2 g / cm³) to the emulsion obtained in step S5. 3 After ultrasonic dispersion, the mixture is stirred for 90 minutes to obtain an environmentally friendly lubricant for drilling fluid.

[0088] The other steps are the same as in Example 2.

[0089] Performance testing

[0090] Preparation of base slurry: Prepare the base slurry according to the ratio of calcium-based bentonite: anhydrous sodium carbonate: distilled water = 25g: 1g: 500mL. Stir the slurry for 60min at 10000r / min using a high-speed mixer GJSS-B12K and cure it in a sealed container at room temperature for 24h to obtain the base slurry.

[0091] 1) Lubrication performance test

[0092] Take 300 mL of base slurry, add 5 wt% lubricant sample, and stir with a high-speed mixer at 11000 r / min for 5 min. Test using a digital display EP-extreme pressure lubrication instrument: turn on the motor, control the torque at 60 RPM and 150 inch-pounds, run for 5 min, and determine the lubrication coefficient of the base slurry and after adding the sample. The test conditions for the base slurry and after adding the sample should be completely consistent.

[0093] Calculate the lubrication coefficient reduction rate using the following formula:

[0094]

[0095] Where: R—reduction rate of lubrication coefficient, %; K0—lubrication coefficient of base slurry; K1—lubrication coefficient of sample slurry.

[0096] The lubrication performance of drilling fluids after adding the lubricants obtained in the embodiments and comparative examples of this invention was measured, and the results are shown in Table 1:

[0097]

[0098]

[0099] As can be seen from the data in Table 1, the drilling fluid coefficient reduction rate after adding lubricants from Examples 1-8 and Comparative Example 1 is greater than 80%, indicating that the lubricants from Examples 1-8 and Comparative Example 1 all have excellent lubrication performance. Comparative Example 2 has low lubrication performance and does not meet lubrication requirements, indicating that the surface-active component of this invention performs better than conventional surfactants. Comparative Example 3 has good lubrication performance, indicating that there is little difference in lubrication effect between solid and hollow glass microspheres.

[0100] 2) Temperature resistance test

[0101] Take 1000 mL of base slurry, add 5 wt% lubricant sample, stir with a high-speed mixer at 11000 r / min for 10 min, hot roll in a hot tumbler at 220℃ for 16 hours, cool to room temperature, and stir at 4000 r / min for 8 min. Measure the performance of the base slurry and the comparative example after adding the sample. The test conditions for the base slurry and the example after adding the sample should be completely consistent.

[0102] The results of the drilling fluid temperature resistance are shown in Table 2:

[0103]

[0104] As can be seen from the data in Table 2, the drilling fluids of Examples 1-8 maintained good rheological properties, and the lubrication coefficient reduction rate was greater than 80% for all of them. This indicates that the lubricants of Examples 1-8 of this invention all have good temperature resistance. Comparative Examples 1-2 showed a lower lubrication coefficient reduction rate, failing to meet lubrication requirements, and also exhibited high-temperature thickening in their rheological properties, indicating that the surface-active component of this invention has better temperature resistance than conventional surfactants. Comparative Example 3 showed good lubrication and rheological properties, indicating that there was little difference in temperature resistance between solid and hollow glass microspheres.

[0105] 3) Stability performance test

[0106] Take 1000 mL of base slurry, add 5 wt% lubricant sample, stir with a high-speed mixer at 11000 r / min for 10 min, hot roll in a hot tumbler at 120℃ for 72 hours, cool to room temperature, and stir at 4000 r / min for 8 min. Measure the performance of the base slurry and the comparative example after adding the sample. The test conditions for the base slurry and the example after adding the sample should be completely consistent.

[0107] The results of the drilling fluid temperature resistance are shown in Table 3:

[0108]

[0109] As can be seen from the data in Table 3, the rheological properties of the drilling fluids in Examples 1-8 are better than those of the base slurry. This is mainly due to the better stability of the lubricant, which also has a beneficial effect on the rheological properties of the drilling fluid. At the same time, the lubrication performance also meets the requirements. Therefore, it can be concluded that the lubricants in Examples 1-8 of this invention all have good stability. The lubrication coefficient reduction rate of Comparative Examples 1-2 is insufficient, mainly because the emulsification effect of the lubricant deteriorates under prolonged high-temperature conditions, resulting in poor lubricity and affecting the rheological properties. This indicates that the stability of the surface-active component of this invention is better than that of conventional surfactants. The lubrication coefficient reduction rate of Comparative Example 3 is low. After the rheological properties were measured, glass microspheres precipitated at the bottom of the cup, indicating that the solid glass microspheres were unevenly distributed in the drilling fluid under prolonged high-temperature conditions.

Claims

1. An environmentally friendly lubricant for drilling fluids, characterized in that, The following components are included by volume percentage: Base oil: 50-70 vol%; Polysorbate-80: 5-12 vol%. Water: 15-30 vol%; Defoamer: 1-3 vol%; Surfactant component: 5–16 vol%; Alkalinity adjuster: 0.5–1.0 vol%; Nano-graphite powder: 2-6 vol%; Glass microspheres: 1-3 vol%; The base oil is a modified vegetable oil that has undergone epoxidation or sulfonation modification; The glass microspheres are hollow quartz glass microspheres with a density of 1.25-1.30 g / cm³. 3 ; The method for synthesizing the surface-active component is as follows: Dissolve (E)-2-octadecenol in 95% ethanol solution to a mass concentration of 8wt%–10wt%, titrate with 0.5mol / L sodium hydroxide using phenolphthalein as an indicator, and after reaching the equivalence point, dilute with water at a mass ratio of 1:30 to obtain solution A. Sodium methylpropenesulfonate was dissolved in water to a concentration of 1 wt%–2 wt%, and the pH was adjusted to 8–9 to obtain solution B. Solution A and solution B are mixed at a mass ratio of 8 to 10:1, and ammonium persulfate initiator is added dropwise. The mixture is stirred at 65 to 85°C and then cooled to room temperature after the reaction is complete to obtain the surface-active component.

2. The environmentally friendly lubricant for drilling fluid as described in claim 1, characterized in that, The vegetable oil is at least one of castor oil, cottonseed oil, or soybean oil.

3. The environmentally friendly lubricant for drilling fluid as described in claim 1, characterized in that, The nano-graphite powder is scaly graphite with a particle size of 300-1000 nm.

4. The environmentally friendly lubricant for drilling fluid as described in claim 1, characterized in that, The hollow quartz glass microspheres have a particle size of 70-75 μm and a hardness of 6 HB.

5. The environmentally friendly lubricant for drilling fluid as described in claim 1, characterized in that, The defoamer is dimethyl silicone oil, and the alkalinity regulator is sodium hydroxide or potassium hydroxide.

6. The environmentally friendly lubricant for drilling fluid as described in claim 1, characterized in that, The initiator dosage is 3% of the total mass fraction of solution A + solution B, the stirring speed is 1000 r / min, and the stirring time is 6-7 h.

7. A method for preparing an environmentally friendly lubricant for drilling fluid according to any one of claims 1-6, characterized in that, The following steps are adopted: S1: Pour the base oil, polysorbate-80, water, and defoamer into the reaction vessel, mix and ultrasonically stir to obtain a uniform emulsion; S2: Add the surfactant component to the emulsion obtained in step S1, disperse it by ultrasonication and stir it evenly, then add the alkalinity regulator and stir it evenly by ultrasonication. S3: Mix nano-graphite powder and glass microspheres with the emulsion obtained in step S2, and then ultrasonically disperse them evenly to obtain an environmentally friendly lubricant for drilling fluid.

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