In-situ preparation method of nano-copper / clay hybrid material in clay and application of nano-copper / clay hybrid material as high-temperature lubricant for water-based drilling fluid

Abstract

The invention discloses a nano-copper / clay hybrid material. The nano-copper / clay hybrid material is prepared by the following steps: fully mixing clay and cupric salt in an aqueous solution for ion exchange; then mixing with a sodium oleate solution, filtering, washing out precipitates, drying, finally heating to 200-350 DEG C in an inert gas atmosphere, and carrying out heat preservation reaction for 1-8 hours; after the reaction is finished, cooling to room temperature, and grinding. According to the method, clay with negative charges firstly adsorbs metal copper ions and then serves as a carrier of in-situ generated solid lubricant nano-copper; and on the other hand, the clay can also be used as a protective agent of the copper nanoparticles, so that the copper nanoparticles have good water solubility, and nano-copper can be prevented from being oxidized. The hybrid material lubricant has good high-temperature stability and can effectively improve the tribological performance of the water-based drilling fluid at high temperature, when 1.0 wt% of the hybrid material lubricant is added into basic slurry, the friction coefficient and the wear rate can still be reduced by 83.7% and 73.5% respectively after the water-based drilling fluid is aged for 16 h at the high temperature of 240 DEG C, and the hybrid material lubricant is expected to serve as a high-temperature-resistant lubricant.

Description

Technical Field

[0001] This invention belongs to the field of novel functional nanomaterial preparation technology, specifically relating to an in-situ preparation method of nano-copper / clay hybrid material in clay and its application as a high-temperature lubricant for water-based drilling fluids. Background Technology

[0002] With the increasing demand for energy and the decreasing availability of shallow and easily exploitable oil and gas, oil and gas exploration is shifting towards deeper formations and complex geological structures. This has led to a growing demand for specialized well techniques such as horizontal wells, ultra-deep wells, cluster wells, and directional wells. The friction between casing and drill pipe, and between drill bit and rock, places higher demands on the lubrication performance of drilling fluids. Simultaneously, the extreme environmental conditions of deeper formations and complex geological structures, such as high temperatures (above 180°C) and high pressures, place increasingly stringent requirements on drilling fluid performance. This presents new challenges to the high-temperature resistance (above 180°C) of commonly used drilling fluid lubricants and has become one of the key factors determining the success or failure of drilling under extreme conditions.

[0003] Developing new high-performance lubricating materials and technologies to effectively reduce friction and wear on drilling equipment is one of the most direct and effective ways to save energy and resources and build a resource-saving society. Compared with oil-based drilling fluids, water-based drilling fluids are cheaper and more environmentally friendly, but their lubrication performance is insufficient, and traditional water-based drilling fluid lubricants have poor stability at high temperatures (above 180°C). Therefore, the development of new high-temperature resistant, high-performance water-based lubricants is urgently needed.

[0004] Clay, due to its inherent properties such as high surface area, good swelling properties, adsorption behavior, and good ion exchange capacity, is a major raw material for drilling fluid formulation. Its main component is layered silicate, which not only improves the rock-carrying capacity and rheological properties of the drilling fluid system but also acts as a thickener and shear enhancer, helping to maintain the gel properties of the drilling fluid. Layered montmorillonite, fibrous sepiolite, and rod-shaped palygorskite are abundant and inexpensive clay materials found in nature. Using clay to support nanoparticles can expand their properties and alter their compatibility.

[0005] Copper possesses excellent conductivity, ductility, and corrosion resistance. As a soft metal, it exhibits low shear strength, the ability to undergo grain boundary slip, and a superior performance-price ratio, demonstrating promising application prospects. However, exposed nano-copper, as a solid lubricant, is mostly insoluble in water and cannot be directly used in water-based drilling fluids. Therefore, based on the electrostatic interaction between negatively charged clay surfaces and metal cations, and using clay as a carrier, leveraging the water solubility, adsorption, and cation exchange properties of clay, as well as the lubricating properties of nano-copper, a nano-copper / clay hybrid solid lubricant is synthesized in situ between clay layers or on the surface through high-temperature decomposition. Summary of the Invention

[0006] The purpose of this invention is to overcome the defects of the prior art and provide a novel nano-copper / clay hybrid material. This nano-copper / clay hybrid material has excellent friction reduction and wear resistance, and solves the problem of insufficient lubrication performance of existing traditional water-based drilling fluid lubricants when facing high temperatures. It has good application prospects as a high-temperature lubricant for water-based drilling fluids.

[0007] This invention also provides an in-situ preparation method of the above-mentioned nano-copper / clay hybrid material in clay. In the reaction, clay acts as both a carrier and a protective agent for the nano-copper, ensuring the compatibility of the copper nanoparticles with water and preventing their oxidation.

[0008] The present invention also provides the application of the above-mentioned nano-copper / clay hybrid material as a high-temperature lubricant for water-based drilling fluids. It is a high-temperature resistant water-based drilling fluid lubricant that can not only significantly reduce the friction coefficient of drilling fluid at room temperature, but also maintain excellent friction reduction and anti-wear performance at high temperatures above 180°C.

[0009] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: A method for in-situ preparation of nano-copper / clay hybrid materials in clay, comprising the following steps: 1) Mix clay and copper salt thoroughly in water for ion exchange; then mix thoroughly with sodium oleate solution, filter, wash the precipitate and dry it, and then heat to 200-350 ℃ and keep it at that temperature for 1-8 h under an inert gas atmosphere; 2) After the reaction is complete, cool to room temperature and grind to obtain the product.

[0010] Specifically, the clay includes, but is not limited to, any one or more of bentonite, sepiolite, montmorillonite, palygorskite, etc.

[0011] Specifically, the copper salt includes, but is not limited to, any one or more of copper chloride, copper sulfate, copper nitrate, and copper acetate.

[0012] Furthermore, the mass ratio of the clay to the copper salt can be 1:1 to 8:1, for example, 1:1, 2:1, 4:1, 8:1, etc. The molar ratio of the copper salt to sodium oleate can be 1:0.5 to 1:3, for example, 1:1, 1:2, 1:3, 2:1, etc. For example, in step 1), 10 g of clay and 1.25 to 5.00 g of copper chloride can be added to a beaker containing 200 mL of water and magnetically stirred until well mixed. Then, 1.12 to 26.76 g of sodium oleate and 100 to 600 mL of water can be added to the beaker and magnetically stirred until well mixed. This mixture is then combined with the clay and copper salt solution.

[0013] Furthermore, in step 1), the reaction temperature can be 200, 230, 250, 300, or 350 °C, etc.; the reaction time can be 60, 120, 180, 240, 300, 360, 420, or 480 min, etc. The heating rate can be 1–4 °C / min.

[0014] Furthermore, in step 1), inert protective gas nitrogen can be continuously introduced into the tubular furnace at a flow rate of approximately 0.5 L / min.

[0015] Furthermore, in step 2), water is used for washing; drying is carried out in a vacuum drying oven at 40-60 ℃ for 8-16 hours.

[0016] This invention provides a nano-copper / clay hybrid material prepared by the above method.

[0017] This invention provides the application of the above-mentioned nano-copper / clay hybrid material as a high-temperature lubricant for water-based drilling fluids. Furthermore, in application, the amount of nano-copper / clay hybrid material added is 0.5%–3.0%.

[0018] The present invention also tested the tribological properties of the nano-copper / clay hybrid material when used as a high-temperature lubricant for water-based drilling fluids. For example, when the concentration was 1.0 wt%, the friction coefficient and wear rate of the water-based drilling fluid decreased by 86.9% and 82.4% respectively before aging; after aging at 240 ℃, the friction coefficient and wear rate of the drilling fluid decreased by 83.7% and 73.5% respectively.

[0019] In this invention, clay serves two purposes: firstly, as a carrier for the solidifying lubricant sodium copper nanoparticles, enabling the copper nanoparticles to nucleate and grow within the clay layers or on its surface; secondly, as a protective agent for the copper nanoparticles, ensuring their good water solubility and preventing oxidation. The method for preparing the copper / clay hybrid material using this invention is simple, convenient, and uses abundant raw materials, making it suitable for large-scale industrial production. The prepared copper / clay hybrid material exhibits good water solubility and stability. Compared with existing technologies, the significant advantages of this invention are as follows: (1) This invention uses clay as a carrier. Clay has good adsorption properties, excellent hydrophilicity, and excellent cation exchange properties. Furthermore, clay is the main raw material for drilling fluid preparation. It can not only improve the rock-carrying capacity and rheological properties of the drilling fluid system, but also play a role in thickening and shearing, which is beneficial to maintaining the gel properties of the drilling fluid.

[0020] (2) In this invention, nano-copper with good temperature resistance and lubrication performance is used as a solid lubricant and combined with clay, a pulping raw material with good dispersion stability and water solubility, to construct nano-copper / clay hybrid material in situ. By utilizing the synergistic effect of the two components, a new high-performance nano-lubricant material for drilling fluid is developed.

[0021] (3) The copper in the nano-copper / clay hybrid material prepared by the present invention is generated in situ between clay layers or on the surface, and has good compatibility with water, which is beneficial for its application in water-based drilling fluids.

[0022] (4) When the nano-copper / clay hybrid material prepared by this invention is added to water-based drilling fluid at a mass concentration of 1.0%, the friction coefficient and wear rate of the water-based drilling fluid are reduced by 86.9% and 82.4% respectively before aging, which shows that it has good tribological properties.

[0023] (5) When the nano-copper / clay hybrid material prepared by this invention is added to water-based drilling fluid at a mass concentration of 1.0%, the friction coefficient and wear rate of the drilling fluid can still be reduced by 83.7% and 73.5% respectively after aging at 240 ℃ for 16 h, which shows excellent high temperature resistance. This lubricant has broad application prospects. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the synthesis process of the nano-copper / clay hybrid material described in this invention; Figure 2 The images show the XRD patterns of the in-situ synthesis of nano-copper / clay hybrid materials at different reaction temperatures in Example 1. Figure 3 The XRD patterns of the nano-copper / clay hybrid materials generated under different feed ratios in Example 3 are shown. Figure 4 Transmission electron microscope image of the nano-copper / clay hybrid material generated in Example 4; Figure 5 The graph shows the friction coefficient curves (left) and average friction coefficient (right) of the hybrid lubricant generated at different reaction temperatures in drilling fluid during tribological experiment 1. Figure 6 The graph shows the friction coefficient curve (left) and average friction coefficient (right) of drilling fluid prepared under different mass ratios of bentonite and copper salt in tribological test 2, with the same addition amount. Figure 7 The friction coefficient curve (left) and average friction coefficient (right) of drilling fluid prepared under different molar ratios of sodium oleate and copper salt for tribological test 3 are shown in the figure. Figure 8 The graph shows the average coefficient of friction (left) and average wear rate (right) of drilling fluid with different amounts of 4-nanometer copper / clay hybrid material added, as shown in the tribological test. Figure 9 The graph shows the average friction coefficient (left) and average wear rate (right) of the drilling fluid after aging at different temperatures for 16 hours in Tribological Test 5. Detailed Implementation

[0025] The technical solution of the present invention will be further described in detail below with reference to the embodiments, but the scope of protection of the present invention is not limited thereto.

[0026] In the embodiments, the raw materials used are all common commercially available products that can be purchased directly, or can be prepared using conventional techniques in the art.

[0027] Room temperature refers to 25 ± 5 ℃.

[0028] Example 1 A method for in-situ preparation of nano-copper / clay hybrid materials in clay (process flow as follows) Figure 1 As shown), the specific steps include: (1) Add 10 g of bentonite and 5 g of copper chloride dihydrate to 200 mL of distilled water and mix them by magnetic stirring at 600 rev / min for 2 h. (2) Add 4.46 g sodium oleate and 100 mL water to a beaker and stir magnetically until well mixed. Then mix with a mixed solution of bentonite and copper chloride at 600 rev / min for 15 min. (3) Filter the solution obtained in (2), wash it with water, and then vacuum dry the obtained solid at 40-60 °C overnight (12 h). (4) The solid obtained in (3) is placed in a tube furnace and heated to a certain temperature (e.g., 200, 230, 250, 300 and 350 ℃ respectively), with a heating rate of 2 ℃ / min. At the same time, inert protective gas nitrogen is continuously introduced at a flow rate of about 0.5 L / min. The reaction is kept at a constant temperature for 2 hours. After the reaction is completed, the solid is cooled to room temperature, taken out and ground to obtain nano-copper / clay hybrid material.

[0029] Figure 2 shows the XRD patterns of the nano-copper / clay hybrid materials synthesized at different temperatures in a tube furnace at reaction temperatures of 200, 230, 250, 300 and 350 °C. The (111), (200) and (220) crystal planes of copper appear at 43.3°, 50.4° and 74.1°, respectively, which are consistent with the standard XRD pattern of copper (JCPDS card No. 04-0836), proving that copper particles are generated at the above different reaction temperatures.

[0030] Example 2 A method for in-situ preparation of nano-copper / clay hybrid materials in clay, specifically including the following steps: (1) Add 10 g of bentonite and copper chloride dihydrate (1.25, 2.5 or 5 g respectively) to 200 mL of distilled water, mix well by magnetic stirring at 600 rev / min for 2 h; (2) Add 4.46 g of sodium oleate and 100 mL of distilled water to a beaker and mix them by magnetic stirring. Then mix them with a mixed solution of bentonite and copper chloride dihydrate. Stir magnetically for 15 min at a speed of 600 rev / min. (3) Filter the solution obtained in (2), wash it with water, and then vacuum dry the obtained solid at 40-60 °C overnight (12 h); (4) The solid obtained in (3) was placed in a tube furnace and heated to 230 °C at a heating rate of 2 °C / min. At the same time, inert protective gas nitrogen was continuously introduced at a flow rate of about 0.5 L / min. The reaction was carried out under these conditions for 2 hours. After the reaction was completed, the solid was cooled to room temperature, removed and ground to obtain nano-copper / clay hybrid material.

[0031] The above synthesis yielded nano-copper / clay hybrid materials with different nano-copper contents. When the copper chloride dihydrate content was 1.25, 2.5, and 5.0 g, the corresponding mass ratios of bentonite to copper salt were 8:1, 4:1, and 2:1, respectively.

[0032] Example 3 A method for in-situ preparation of nano-copper / clay hybrid materials in clay, specifically including the following steps: (1) Add 10 g of bentonite and 5 g of copper chloride dihydrate to 200 mL of distilled water and mix them by magnetic stirring at 600 rev / min for 2 h. (2) Sodium oleate (4.46, 8.92, 17.85 or 26.76 g) and distilled water (100, 200, 400 or 600 mL respectively) were added to a beaker and mixed with magnetic stirring. Then, the mixture was mixed with a solution of bentonite and copper chloride dihydrate and stirred magnetically for 15 min at 600 rev / min. (3) Filter the solution obtained in (2), wash it with water, and then vacuum dry the obtained solid at 40-60 °C overnight (12 h). (4) The solid obtained in (3) was placed in a tube furnace and heated to 230 °C at a heating rate of 2 °C / min. At the same time, inert protective gas nitrogen was continuously introduced at a flow rate of about 0.5 L / min. The reaction was carried out under these conditions for 2 hours. After the reaction was completed, the solid was cooled to room temperature, removed and ground to obtain nano-copper / clay hybrid material.

[0033] The above-mentioned copper / clay nanomaterials synthesized with different ratios of copper chloride dihydrate to sodium oleate, such as... Figure 3 The XRD pattern of the nano-copper / clay hybrid material generated by the reaction is shown. When the mass of sodium oleate is 4.46, 8.92, 17.85, and 26.76 g, the molar ratio of copper chloride dihydrate to sodium oleate is 2:1, 1:1, 1:2, and 1:3, respectively. It can be seen that changing the feed ratio can generate nano-copper / clay hybrid materials, but their tribological properties are somewhat different.

[0034] Example 4 A method for in-situ preparation of nano-copper / clay hybrid materials in clay, specifically including the following steps: (1) Add 10 g of bentonite and 2.5 g of copper chloride dihydrate to 200 mL of distilled water and mix them by magnetic stirring at 600 rev / min for 2 h. (2) Add 8.92 g of sodium oleate and 200 mL of water to a beaker and stir magnetically until well mixed. Then mix thoroughly with the mixed solution of bentonite and copper chloride. Stir magnetically for 15 min at a speed of 600 rev / min. (3) Filter the solution obtained in (2), wash it with water, and then vacuum dry the obtained solid at 40-60 °C overnight (12 h). (4) The solid obtained in (3) was placed in a tube furnace and heated at 230 °C at a heating rate of 2 °C / min. At the same time, inert protective gas nitrogen was continuously introduced at a flow rate of about 0.5 L / min. The reaction was carried out at a constant temperature for 2 hours. After the reaction was completed, the solid was cooled to room temperature, removed and ground to obtain nano-copper / clay hybrid material.

[0035] Figure 4 Transmission electron microscope (TEM) images of the nano-copper / clay hybrid material generated in Example 4 of this study are provided. The images show that the elemental copper is represented by black particles with a diameter of approximately 30–90 nm, exhibiting good dispersion. Simultaneously, the wrinkles in the images represent layered bentonite. This indicates that copper is generated in situ on the bentonite, adhering to the surface or interlayer of the bentonite to form the nano-copper / clay hybrid material.

[0036] Example 5 A method for in-situ preparation of nano-copper / clay hybrid materials in clay, specifically including the following steps: (1) Add 10 g sepiolite and 5 g copper nitrate trihydrate to 200 mL of distilled water and mix them by magnetic stirring at 600 rev / min for 2 h. (2) Add 3.15 g sodium oleate and 100 mL water to a beaker and stir magnetically until well mixed. Then mix it with the mixture of sepiolite and copper nitrate solution and stir magnetically for 15 min at a speed of 600 rev / min. (3) Filter the solution obtained in (2), wash it with water, and then vacuum dry the obtained solid at 40-60 °C overnight (12 h). (4) The solid obtained in (3) was placed in a tube furnace and heated at 300 °C at a heating rate of 2 °C / min. At the same time, inert protective gas nitrogen was continuously introduced at a flow rate of about 0.5 L / min. The reaction was carried out at a constant temperature for 8 hours. After the reaction was completed, the solid was cooled to room temperature, removed and ground to obtain nano-copper / clay hybrid material.

[0037] Example 6 A method for in-situ preparation of nano-copper / clay hybrid materials in clay, specifically including the following steps: (1) Add 10 g palygorskite and 5 g copper acetate monohydrate to 200 mL of distilled water and mix them by magnetic stirring at 600 rev / min for 2 h. (2) Add 3.81 g sodium oleate and 100 mL water to a beaker and stir magnetically until well mixed. Then mix it with the mixed solution of palygorskite and copper acetate. Stir magnetically for 15 min at a speed of 600 rev / min. (3) Filter the solution obtained in (2), wash it with water, and then vacuum dry the obtained solid at 40-60 °C overnight (12 h). (4) The solid obtained in (3) was placed in a tube furnace and heated to 260 °C at a heating rate of 2 °C / min. At the same time, inert protective gas nitrogen was continuously introduced at a flow rate of about 0.5 L / min. The reaction was carried out at a constant temperature for 6 hours. After the reaction was completed, the solid was cooled to room temperature, removed and ground to obtain nano-copper / clay hybrid material.

[0038] Example 7 A method for in-situ preparation of nano-copper / clay hybrid materials in clay, specifically including the following steps: (1) Add 10 g of montmorillonite and 5 g of copper sulfate pentahydrate to 200 mL of distilled water and mix them by magnetic stirring at 600 rev / min for 2 h. (2) Add 7.96 g sodium oleate and 200 mL water to a beaker and stir magnetically until well mixed. Then mix with the mixed solution of montmorillonite and copper sulfate. Stir magnetically for 15 min at a speed of 600 rev / min. (3) Filter the solution obtained in (2), wash it with water, and then vacuum dry the obtained solid at 40-60 °C overnight (12h). (4) The solid obtained in (3) was placed in a tube furnace and heated at 230 °C with a heating rate of 2 °C / min. At the same time, inert protective gas nitrogen was continuously introduced at a flow rate of about 0.5 L / min. The reaction was carried out at a constant temperature for 4 hours. After the reaction was completed, the solid was cooled to room temperature, removed and ground to obtain nano-copper / clay hybrid material.

[0039] Tribological Experiment 1 The nano-copper / clay hybrid material prepared in Example 1 was added to the base slurry at a mass fraction of 1.0%. The base slurry was prepared from bentonite, sodium carbonate, and water (mass ratio 3:0.2:100). Tribological tests were conducted on a UMT-2 micro-friction and wear testing machine with a GCr15 steel ball and GCr15 steel sheet as the friction pair under a load of 8 N, a frequency of 2 Hz, a stroke of 5 mm, and a time of 30 min. The experimental results are shown in […]. Figure 5 .

[0040] Figure 5 The results showed that the nano-copper / clay hybrid materials synthesized at 200, 230, 250, 300 and 350 ℃ could reduce the friction coefficient (the initial friction coefficient was 0.5064 without the addition of nano-copper / clay hybrid material), and the relationship between the friction coefficient and the reaction temperature showed a trend of first decreasing and then increasing. The friction coefficient was the lowest at the reaction temperature of 230 ℃, with a friction coefficient of 0.1879.

[0041] Tribological Experiment 2 The nano-copper / clay hybrid material prepared in Example 2 was added to the base slurry at a mass fraction of 1.0%. The base slurry was prepared from bentonite, sodium carbonate, and water (mass ratio 3:0.2:100). Tribological tests were conducted on a UMT-2 micro-friction and wear testing machine with a GCr15 steel ball and GCr15 steel sheet as the friction pair under a load of 8 N, a frequency of 2 Hz, a stroke of 5 mm, and a time of 30 min. The experimental results are shown in […]. Figure 6 .

[0042] Figure 6 The results showed that the tribological properties of the nano-copper / clay hybrid materials prepared under different bentonite-copper salt mass ratios, when added to drilling fluids, were largely unaffected by the bentonite-copper salt mass ratio. However, compared to the friction coefficient of 0.5064 without the addition of the nano-copper / clay hybrid material, the friction coefficient decreased to 0.1958 after adding 1.0% lubricant at a bentonite-copper salt mass ratio of 4:1, a reduction of 61.3%.

[0043] Tribological Test 3 The nano-copper / clay hybrid material prepared in Example 3 was added to the base slurry at a mass fraction of 1.0%. The base slurry was prepared from bentonite, sodium carbonate, and distilled water (mass ratio 3:0.2:100). Tribological tests were conducted on a UMT-2 micro-friction and wear testing machine with a GCr15 steel ball and GCr15 steel sheet as the friction pair under a load of 8 N, a frequency of 2 Hz, a stroke of 5 mm, and a time of 30 min. The experimental results are shown in […]. Figure 7 .

[0044] Figure 7 The results showed that the tribological properties of nano-copper / clay hybrid materials prepared under different molar ratios of sodium oleate and copper salt as lubricants in drilling fluids varied with the ratio. The tribological properties were optimal when the ratio of sodium oleate to copper salt was 2:1, with an average friction coefficient of only 0.0683.

[0045] Tribological Test 4 The nano-copper / clay hybrid material prepared in Example 4 above was added to the base slurry at mass fractions of 0.50%, 0.75%, 1.0%, 2.0%, and 3.0%. The base slurry was prepared from bentonite, sodium carbonate, and water (mass ratio 3:0.2:100). Tribological tests were conducted on a UMT-2 micro-friction and wear testing machine under conditions of 8 N load, 2 Hz frequency, 5 mm stroke, and 30 min time, using GCr15 steel balls and P110 steel sheets as the friction pair. The experimental results are shown in […]. Figure 8 .

[0046] Figure 8 The results showed that compared with the base mud, the drilling fluid friction coefficient was significantly reduced after adding the lubricant of this invention. At a content of 1.0 wt%, the drilling fluid friction coefficient (COF) decreased from 0.5064 to 0.0661, a reduction of 86.9%, and the wear rate decreased from 7.930 × 10⁻⁶. −6 mm 3 ·(N·m) −1 Reduced to 1.396×10 −6 mm 3 ·(N·m) −1 The friction was reduced by 82.4%, indicating that the nano-copper / clay hybrid material plays a significant role in reducing friction and wear as a lubricant for water-based drilling fluids.

[0047] Tribological Test 5 The nano-copper / clay hybrid material prepared in Example 4 was added to the base drilling mud at a mass fraction of 1.0%. The base drilling mud was prepared from bentonite, sodium carbonate, and water (mass ratio 3:0.2:100) and aged for 16 h at different temperatures (25 ℃, 150 ℃, 180 ℃, 210 ℃, 240 ℃) to obtain aged drilling fluid. Tribological tests were conducted on a UMT-2 micro-friction and wear testing machine under conditions of 8 N load, 2 Hz frequency, 5 mm stroke, and 30 min time, using GCr15 steel balls and P110 steel sheets as the friction pair. The experimental results are shown in […]. Figure 9 .

[0048] Figure 9 The results showed that compared with the base mud, the friction coefficient of the drilling fluid after adding the lubricant of this invention was significantly reduced. Regardless of the aging temperature, the friction coefficient (COF) of the drilling fluid with a content of 1.0 wt% was significantly reduced. After the friction coefficient stabilized, the average reduction rate of the friction coefficient was over 80%, and the wear rate was reduced by about 70%. After aging at 180 ℃ for 16 h, the friction coefficient and wear rate decreased by 85.3% and 68.1%, respectively. After further aging at 210 ℃ for 16 h, the friction coefficient and wear rate decreased by 85.1% and 77.6%, respectively. Even after high-temperature aging at 240 ℃ for 16 h, it still exhibited excellent tribological properties, with the friction coefficient decreasing from 0.5114 to 0.0835, a reduction rate of 83.7%, and the wear rate decreasing by 73.5%. Therefore, it can be concluded that the nano-copper / clay hybrid material, as a drilling fluid lubricant, possesses excellent tribological properties and high-temperature resistance.

[0049] The nano-copper / clay hybrid materials prepared in Examples 1 to 7 were analyzed by XRD and TEM. The results showed that all products were nano-copper / clay hybrid materials. Tribological tests 1 to 4 showed that their tribological properties varied with the reaction temperature and reactant ratio. Optimizing the reaction conditions resulted in a reduction of the friction coefficient by 86.9% and the wear rate by 82.4% at 25 °C. Tribological test 5 showed that after aging at 240 °C for 16 h, the friction coefficient and wear rate of the drilling fluid were still reduced by 83.7% and 73.5%, respectively. Therefore, it can be concluded that the nano-copper / clay hybrid material, as a drilling fluid lubricant, possesses excellent tribological properties and high-temperature resistance.

[0050] In summary, the nano-copper / clay hybrid material prepared in situ in clay by this invention exhibits excellent tribological properties and high-temperature resistance as a drilling fluid lubricant.

Claims

1. A method for in-situ preparation of a nanocopper / clay hybrid material in clay, characterized in that, The method comprises the following steps: 1) mixing clay and copper salt in water, then mixing with sodium oleate solution, filtering, washing the precipitate and drying, then heating to 200-350 ℃ under inert gas atmosphere and keeping the temperature for 1-8 h; 2) after the reaction, cooling to room temperature, grinding to obtain the product.

2. The method for in-situ preparation of nanocopper / clay hybrid material in clay as claimed in claim 1, wherein, The clay is any one or more than two of bentonite, sepiolite, montmorillonite and palygorskite.

3. The method of in-situ preparation of nanocopper / clay hybrid material in clay as claimed in claim 1, wherein, The copper salt is any one or more than two of copper chloride, copper sulfate, copper nitrate and copper acetate.

4. The method of in-situ preparation of nanocopper / clay hybrid material in clay as claimed in claim 1, wherein, The mass ratio of clay to copper salt is 1:1-8:

1.

5. The method of in-situ preparation of nanocopper / clay hybrid material in clay as claimed in claim 1, wherein, The molar ratio of copper salt to sodium oleate is 1:0.5-1:

3.

6. The method of in-situ preparation of nanocopper / clay hybrid material in clay as claimed in claim 1, wherein, In step 1), the reaction temperature is 200, 230, 250, 300 or 350 ℃; the reaction time is 60, 120, 180, 240, 300, 360, 420 or 480 min.

7. The method of in-situ preparation of nanocopper / clay hybrid material in clay as claimed in claim 1, wherein, In step 2), water is used for washing; The drying is performed in a vacuum drying oven at 40-60 ℃ for 8-16 h.

8. The nano copper / clay hybrid material prepared by the method of any one of claims 1-7.

9. The use of the nano copper / clay hybrid material of claim 8 as a high-temperature lubricant for water-based drilling fluid.

10. Use of the nanocopper / clay hybrid material according to claim 9 as a high temperature lubricant for water-based drilling fluids, characterized in that, The addition amount of the nano copper / clay hybrid material is 0.5%-3.0%.

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