A suspension stabilizer for oil-based drilling and completion fluids and a method of making the same

Abstract

The application provides a kind of oil-based drilling and completion fluid suspending stabilizer and a preparation method thereof.The oil-based drilling and completion fluid suspending stabilizer includes modified bentonite, modified nano-silica and nano-calcium carbonate, wherein the modified bentonite is obtained by using a first silane coupling agent for first modification treatment of bentonite, and the modified nano-silica is obtained by using a second silane coupling agent for second modification treatment of nano-silica.The oil-based drilling and completion fluid suspending stabilizer of the application enhances the suspending stability of oil-based drilling and completion fluid.

Description

Technical Field

[0001] This application relates to a suspension stabilizer for oil-based drilling and completion fluids and its preparation method, belonging to the technical field of oil-based drilling fluids for petroleum drilling. Background Technology

[0002] Ultra-deep formations have become a key area for increasing oil and gas reserves and production in my country. However, the geological conditions are extremely complex, and drilling fluids face extreme environments such as ultra-high temperature, ultra-high pressure, and ultra-high salinity. In existing technologies, oil-based drilling and completion fluids are prone to degradation of system performance due to the failure of treatment agents when left to stand for a long time under high temperature conditions. This can lead to the settling and blockage of the wellbore by solid particles such as weighting materials, preventing drilling and completion tools from being lowered to the bottom of the well and causing huge losses.

[0003] In existing technologies, viscosifiers for oil-based drilling and completion fluids are key agents for ensuring the rheological properties and settling stability of the system. At present, viscosifiers mainly include two categories: organic clays and oil-soluble polymers. However, under high-temperature conditions, the active groups on the surface of organic clays are prone to desorption and failure, and the chemical bonds of oil-soluble polymers break or functional groups fail at high temperatures, leading to the problem of rheological instability of oil-based drilling and completion fluids under high-temperature conditions. Therefore, there is an urgent need for a suspension stabilizer for oil-based drilling and completion fluids suitable for high-temperature deep wells. Summary of the Invention

[0004] This application provides a suspension stabilizer for oil-based drilling and completion fluids and its preparation method, in order to solve the problem of rheological instability of oil-based drilling and completion fluids under high-temperature conditions in the prior art.

[0005] In one aspect, the present invention provides a suspension stabilizer for oil-based drilling and completion fluids, comprising modified sepiolite, modified nano-silica, and nano-calcium carbonate, wherein the modified sepiolite is obtained by first modifying the sepiolite with a first silane coupling agent, and the modified nano-silica is obtained by second modifying the nano-silica with a second silane coupling agent.

[0006] In some implementations, the first modification treatment includes:

[0007] Sepiolite was acid-treated with acid to obtain acid-treated sepiolite.

[0008] Acid-treated sepiolite was grafted using a first silane coupling agent.

[0009] In some implementations, the pH during grafting is 9–12.

[0010] In some implementations, the second modification treatment includes:

[0011] Nano-silica was modified using a second silane coupling agent – ​​an alcohol-water solution.

[0012] In some embodiments, the mass ratio of modified sepiolite, modified nano silica, and nano calcium carbonate is (80-90):(10-20):(5-10).

[0013] In some embodiments, the first silane coupling agent is selected from at least one of n-octyltriethoxysilane, n-butyltriethoxysilane, and neopentyltriethoxysilane; and / or,

[0014] The second silane coupling agent is selected from at least one of aminopropyltriethoxysilane, aminopropyltrimethoxysilane, and 2-aminoethyl-aminopropyltrimethoxysilane.

[0015] In some embodiments, the mass ratio of sepiolite to the first silane coupling agent is (60-80):(30-40); and / or,

[0016] The mass ratio of nano-silica to the second silane coupling agent is (10-30):1.

[0017] In some embodiments, the particle size of the sepiolite is at least one selected from 500, 1000, and 2000; and / or,

[0018] The median particle size of nano-silica is 50 nm; and / or,

[0019] The particle size of nano-calcium carbonate is 50 nm.

[0020] In some embodiments, the reaction temperature in the first modification treatment is 70-90°C, and the time is 8-10 hours; and / or,

[0021] In the second modification treatment, the reaction temperature is 50-80℃ and the time is 3-5h.

[0022] In another aspect, the present invention provides a method for preparing the above-mentioned suspension stabilizer for oil-based drilling and completion fluids, comprising the following steps:

[0023] The first modification treatment of sepiolite was carried out using a first silane coupling agent to obtain modified sepiolite.

[0024] The nano-silica was subjected to a second modification treatment using a second silane coupling agent to obtain modified nano-silica.

[0025] Modified sepiolite, modified nano-silica, and nano-calcium carbonate are mixed and treated to obtain a suspension stabilizer for oil-based drilling and completion fluids.

[0026] This application provides a suspension stabilizer for oil-based drilling and completion fluids and its preparation method, comprising modified sepiolite, modified nano-silica, and nano-calcium carbonate. The modified sepiolite is obtained by first modifying sepiolite with a first silane coupling agent, thereby improving the dispersion state of the sepiolite fiber bundles. The modified sepiolite, relying on its stable fiber structure, introduces a three-dimensional skeleton into the spatial network structure formed by the layered organic soil, thereby inhibiting the aggregation and stacking of organic soil due to high-temperature deactivation and enhancing the structural force between droplets of water-in-oil emulsion.

[0027] Modified nano-silica is obtained by second modification of nano-silica using a second silane coupling agent. After modification by the second silane coupling agent, nano-silica reacts with long-chain organic acids, which improves its dispersibility in the oil phase. It can construct a complex spatial network structure in water-in-oil emulsion, improve the strength of the gel structure, and enhance the suspension stability of water-in-oil drilling fluid.

[0028] The surface and small size effects of modified sepiolite and nano-calcium carbonate nanoparticles stabilize the three-dimensional network structure of the system, effectively improving the system's high-temperature and high-pressure sedimentation and rheological stability. Under high temperature and high pressure of 220℃ / 100MPa, the dynamic shear force and 6-turn reading are greater than 15Pa and 10, respectively. No sedimentation occurred after standing at 220℃ for 15 days, which can ensure the stability of the performance of high-temperature deep well oil-based drilling and completion fluids and is beneficial to downhole construction safety. Detailed Implementation

[0029] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below. The specific embodiments listed below are merely descriptions of the principles and features of the present invention, and the examples are only for explaining the present invention and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] This invention provides a suspension stabilizer for oil-based drilling and completion fluids, comprising modified sepiolite, modified nano-silica, and nano-calcium carbonate. The modified sepiolite is obtained by first modifying the sepiolite with a first silane coupling agent, and the modified nano-silica is obtained by second modifying the nano-silica with a second silane coupling agent.

[0031] In this invention, the mass ratio of modified sepiolite, modified nano-silica, and nano-calcium carbonate can be (80-90):(10-20):(5-10).

[0032] The mass ratio of sepiolite to first silane coupling agent can be (60-80):(30-40).

[0033] The mass ratio of nano-silica to the second silane coupling agent can be (10-30):1.

[0034] The first silane coupling agent may be selected from at least one of n-octyltriethoxysilane, n-butyltriethoxysilane, and neopentyltriethoxysilane.

[0035] The second silane coupling agent may be selected from at least one of aminopropyltriethoxysilane, aminopropyltrimethoxysilane, and 2-aminoethyl-aminopropyltrimethoxysilane.

[0036] The particle size of sepiolite can be at least one of 500, 1000, and 2000.

[0037] The median particle size of nano-silica can be 50 nm.

[0038] The particle size of nano-calcium carbonate can be 50 nm.

[0039] The first modification treatment of sepiolite using a first silane coupling agent improves the dispersion of its fiber bundles. The resulting modified sepiolite, with its stable fiber structure, introduces a three-dimensional framework to the spatial network structure formed by the layered organic soil, thereby inhibiting the aggregation and stacking of organic soil due to high-temperature deactivation and enhancing the structural forces between droplets in the water-in-oil emulsion. The second modification treatment of nano-silica using a second silane coupling agent allows the modified nano-silica to react with long-chain organic acids, improving its dispersibility in the oil phase. This enables the construction of a complex spatial network structure in the water-in-oil emulsion, improving the strength of the gel structure and enhancing the suspension stability of the water-in-oil drilling fluid.

[0040] The surface and small size effects of modified sepiolite and nano-calcium carbonate nanoparticles stabilize the three-dimensional network structure of the system, effectively improving the system's high-temperature and high-pressure sedimentation and rheological stability. Under high temperature and high pressure of 220℃ / 100MPa, the dynamic shear force and 6-turn reading are greater than 15Pa and 10, respectively. No sedimentation occurred after standing at 220℃ for 15 days, which can ensure the stability of the performance of high-temperature deep well oil-based drilling and completion fluids and is beneficial to downhole construction safety.

[0041] In some implementations, the first modification process may include:

[0042] Sepiolite was acid-treated with acid to obtain acid-treated sepiolite.

[0043] Acid-treated sepiolite was grafted using a first silane coupling agent.

[0044] In this invention, acid solution can refer to dilute hydrochloric acid solution, such as 1 mol / L dilute hydrochloric acid solution.

[0045] Acid treatment refers to adding sepiolite to a reaction vessel containing a dilute hydrochloric acid solution for treatment, and obtaining acid-treated sepiolite after the treatment is completed.

[0046] Grafting treatment can refer to dispersing the first silane coupling agent in a solvent and stirring until homogeneous to obtain a mixed solution of the first silane coupling agent. Then, the mixed solution of the first silane coupling agent is heated to the reaction temperature, and acid-treated sepiolite is added to the mixed solution of the first silane coupling agent to carry out the reaction. After the reaction, modified sepiolite is obtained.

[0047] For example, the preparation process of modified sepiolite may include:

[0048] (1) Add a certain mass of sepiolite to a reaction vessel containing 1 mol / L dilute hydrochloric acid solution and treat for 30 min.

[0049] (2) After the treatment is completed, pour it into a vacuum filtration flask, rinse it with anhydrous ethanol and deionized water in sequence until neutral, dry and crush it to obtain acid-treated sepiolite.

[0050] (3) Disperse one or more of n-octyltriethoxysilane, n-butyltriethoxysilane and neopentyltriethoxysilane in an ethanol / water mixture in a three-necked flask to obtain the first silane coupling agent-alcohol aqueous solution, and turn on the stirrer to stir at 300 r / min until uniform.

[0051] (4) Heat the well-stirred first silane coupling agent-alcohol aqueous solution to the reaction temperature, add the acid-treated sepiolite to the first silane coupling agent-alcohol aqueous solution, add a certain amount of ammonia to adjust the pH value of the solution, and react under mechanical stirring at 300 r / min.

[0052] (5) After the reaction was completed, the mixture was washed with anhydrous ethanol and deionized water until neutral, and then dried and pulverized at 105°C to obtain modified sepiolite.

[0053] In step (1), the preferred particle size of the sepiolite is 1000 mesh.

[0054] Step (3) The first silane coupling agent is preferably n-octyltriethoxysilane.

[0055] In step (3), the volume ratio of ethanol to water in the ethanol / water mixed solution can be 90:10.

[0056] The reaction temperature in step (4) can be 70-90℃, preferably 80℃, and the reaction time can be 8-10h.

[0057] In step (4), the mass ratio of acid-treated sepiolite to the first silane coupling agent can be (50-90):(10-50), preferably 60:40.

[0058] In step (4), the pH value of the solution after adjustment with ammonia can be 9 to 12, preferably 10.

[0059] In some implementations, the second modification process may include:

[0060] Nano-silica was modified using a second silane coupling agent – ​​an alcohol-water solution.

[0061] The second silane coupling agent-alcohol aqueous solution can be obtained by dispersing the second silane coupling agent in a mixed solution of ethanol and water and stirring until homogeneous.

[0062] For example, the preparation process of modified silica may include:

[0063] (1) Disperse the second silane coupling agent in a mixed solution of ethanol and water to obtain the second silane coupling agent-alcohol aqueous solution, and turn on the stirrer to stir at 300r / min until uniform.

[0064] (2) Add nano-silica to the second silane coupling agent-alcohol aqueous solution in step (1) and sonicate for 10 min.

[0065] (3) The above reactants were stirred at 150 r / min, the pH was adjusted to 10 with ammonia, the temperature was raised to the reaction temperature and kept at that temperature for a certain time, the sample was separated by anhydrous ethanol by vacuum filtration, and thoroughly washed with deionized water, then dried and pulverized to obtain nano-silica with surface modification.

[0066] In step (1), the second silane coupling agent is preferably aminopropyltriethoxysilane.

[0067] In step (1), the volume ratio of ethanol to water can be 90:10.

[0068] The amount of nano-silica added in step (2) is 10 to 30 times the mass of the second silane coupling agent, preferably 20 times.

[0069] The reaction temperature in step (3) is 50-80℃, preferably 65℃.

[0070] A second aspect of the present invention provides a method for preparing the above-mentioned suspension stabilizer for oil-based drilling and completion fluids, comprising the following steps:

[0071] The first modification treatment of sepiolite was carried out using a first silane coupling agent to obtain modified sepiolite.

[0072] The nano-silica was subjected to a second modification treatment using a second silane coupling agent to obtain modified nano-silica.

[0073] Modified sepiolite, modified nano-silica, and nano-calcium carbonate are mixed and treated to obtain a suspension stabilizer for oil-based drilling and completion fluids.

[0074] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0075] Unless otherwise specified, the reagents, materials and instruments used in the following examples are all conventional reagents, materials and instruments in the art, and can be obtained commercially. The reagents involved can also be synthesized by conventional methods in the art.

[0076] In the materials used in the examples, No. 3 white oil was purchased from Guangzhou Maoming Petrochemical Co., Ltd.

[0077] Deionized water, anhydrous ethanol, ammonia, hydrochloric acid, calcium oxide, and calcium chloride were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., and were of analytical grade.

[0078] The sepiolite was purchased from Dingxing County Antai Hengxin New Thermal Insulation Materials Co., Ltd.

[0079] octyltriethoxysilane, butyltriethoxysilane, and neopentyltriethoxysilane were purchased from Guangzhou Zhongjie Chemical Technology Co., Ltd., with a purity of ≥98%.

[0080] γ-aminopropyltriethoxysilane, nano-silica (50 nm), and nano-calcium carbonate (50 nm) were purchased from Shanghai Maclean Biochemical Technology Co., Ltd., and were of analytical grade.

[0081] The main emulsifier, co-emulsifier, filtration loss reducer, and organic soil were all produced by China Petroleum Engineering Technology Research Institute Co., Ltd.

[0082] The barite was purchased from Ankang Liyuan Mining Co., Ltd.

[0083] Example 1

[0084] This embodiment provides a suspension stabilizer for oil-based drilling and completion fluids, which is prepared by the following method:

[0085] (1) Add 60 parts of sepiolite with a particle size of 1000 mesh to a solution containing 1 mol / L dilute hydrochloric acid and treat for 30 min to obtain a sepiolite mixed solution. Rinse with anhydrous ethanol and deionized water in sequence until neutral, then dry and pulverize to obtain acid-treated sepiolite.

[0086] (2) In a three-necked flask, 40 parts of n-octyltriethoxysilane were dispersed in a mixed solution of 100 parts of ethanol:water with a volume ratio of 90:10 to obtain an aqueous solution of n-octyltriethoxysilane-alcohol. The stirrer was turned on and stirred at 300 r / min until uniform. The aqueous solution of n-octyltriethoxysilane-alcohol was heated to 80°C. Acid-treated sepiolite was added to the aqueous solution of n-octyltriethoxysilane-alcohol. Then ammonia was added to adjust the pH of the solution to 10. The reaction was carried out under mechanical stirring at 300 r / min for 8 h. After the reaction was completed, the solution was washed with anhydrous ethanol and deionized water until neutral. The solution was dried and pulverized at 105°C to obtain modified sepiolite.

[0087] (3) Disperse 2 parts of aminopropyltriethoxysilane into 100 parts of a mixed solution of ethanol:water in a volume ratio of 90:10 to obtain an aminopropyltriethoxysilane-alcohol aqueous solution. Stir the mixture at 300 r / min until uniform. Add 40 parts of nano silica and sonicate for 10 min. Adjust the pH to 10 with ammonia water while stirring at 150 r / min. Raise the temperature to 65℃ and keep it warm for 3 h. Separate the sample with anhydrous ethanol by vacuum filtration and wash it thoroughly with deionized water. Then dry and pulverize to obtain nano silica with surface modification.

[0088] (4) Mix 80 parts of modified sepiolite, 10 parts of modified nano silica and 10 parts of nano calcium carbonate to obtain a suspension stabilizer for oil-based drilling and completion fluid.

[0089] Example 2

[0090] The difference between the preparation method of the oil-based drilling and completion fluid suspension stabilizer in this embodiment and the preparation method of the oil-based drilling and completion fluid suspension stabilizer in Example 1 is as follows:

[0091] In step (1), 90 parts of sepiolite with a particle size of 1000 mesh were added to a solution of 1 mol / L dilute hydrochloric acid and treated for 30 min to obtain a sepiolite mixed solution;

[0092] In step (2), 10 parts of n-octyltriethoxysilane are dispersed in a mixed solution of 100 parts of ethanol and water in a volume ratio of 90:10 in a three-necked flask to obtain an aqueous solution of n-octyltriethoxysilane-alcohol.

[0093] Example 3

[0094] The difference between the preparation method of the oil-based drilling and completion fluid suspension stabilizer in this embodiment and the preparation method of the oil-based drilling and completion fluid suspension stabilizer in Example 1 is as follows:

[0095] In step (2), 40 parts of neopentyltriethoxysilane were dispersed in a mixed solution of 100 parts of ethanol and water in a volume ratio of 90:10 in a three-necked flask to obtain a neopentyltriethoxysilane-alcohol aqueous solution. The stirrer was turned on and stirred at 300 r / min until uniform. The neopentyltriethoxysilane-alcohol aqueous solution was heated to 80°C. Acid-treated sepiolite was added to the neopentyltriethoxysilane-alcohol aqueous solution, and then ammonia was added to adjust the pH of the solution to 10. The reaction was carried out under mechanical stirring at 300 r / min for 8 hours. After the reaction was completed, the solution was washed with anhydrous ethanol and deionized water until neutral. The solution was dried and pulverized at 105°C to obtain modified sepiolite.

[0096] In step (3), 20 parts of nano-silica are added and then ultrasonically treated for 10 minutes.

[0097] Example 4

[0098] The difference between the preparation method of the oil-based drilling and completion fluid suspension stabilizer in this embodiment and the preparation method of the oil-based drilling and completion fluid suspension stabilizer in Example 1 is as follows:

[0099] In step (2), 40 parts of n-octyltrimethoxysilane were dispersed in a mixed solution of 100 parts of ethanol and water in a volume ratio of 90:10 in a three-necked flask to obtain an aqueous solution of n-octyltrimethoxysilane-alcohol. The stirrer was turned on and stirred at 300 r / min until uniform. The aqueous solution of n-octyltrimethoxysilane-alcohol was heated to 80°C. Acid-treated sepiolite was added to the aqueous solution of n-octyltrimethoxysilane-alcohol. Then ammonia was added to adjust the pH of the solution to 10. The reaction was carried out under mechanical stirring at 300 r / min for 8 hours. After the reaction was completed, the solution was washed with anhydrous ethanol and deionized water until neutral. The solution was dried and pulverized at 105°C to obtain modified sepiolite.

[0100] Example 5

[0101] The difference between the preparation method of the oil-based drilling and completion fluid suspension stabilizer in this embodiment and the preparation method of the oil-based drilling and completion fluid suspension stabilizer in Example 1 is as follows:

[0102] In step (3), 2 parts of aminopropyltrimethoxysilane were dispersed in 100 parts of a mixed solution of ethanol and water in a volume ratio of 90:10 to obtain an aminopropyltrimethoxysilane-alcohol aqueous solution. The stirrer was turned on and stirred at 300 r / min until uniform. 40 parts of nano silica were added and ultrasonically treated for 10 min. The pH was adjusted to 10 with ammonia water while stirring at 150 r / min. The temperature was raised to 65℃ and kept at that temperature for 3 h. The sample was separated by anhydrous ethanol using a vacuum filtration method and thoroughly washed with deionized water. Then it was dried and pulverized to obtain nano silica with surface modification.

[0103] Example 6

[0104] The difference between the preparation method of the oil-based drilling and completion fluid suspension stabilizer in this embodiment and the preparation method of the oil-based drilling and completion fluid suspension stabilizer in Example 1 is as follows:

[0105] In step (2), the aqueous solution of n-octyltriethoxysilane-alcohol is heated to 90°C;

[0106] In step (3), the temperature is raised to 80°C and kept warm for 3 hours.

[0107] Example 7

[0108] The difference between the preparation method of the oil-based drilling and completion fluid suspension stabilizer in this embodiment and the preparation method of the oil-based drilling and completion fluid suspension stabilizer in Example 1 is as follows:

[0109] In step (2), the reaction is carried out for 10 hours under mechanical stirring at 300 r / min;

[0110] In step (3), the temperature is raised to 65°C and kept warm for 5 hours.

[0111] Example 8

[0112] The difference between the preparation method of the oil-based drilling and completion fluid suspension stabilizer in this embodiment and the preparation method of the oil-based drilling and completion fluid suspension stabilizer in Example 1 is as follows:

[0113] In step (1), 60 portions of sepiolite with a particle size of 2000 mesh were added to a solution containing 1 mol / L dilute hydrochloric acid and treated for 30 minutes to obtain a sepiolite mixed solution.

[0114] Test case

[0115] This test case uses the oil-based drilling and completion fluid suspension stabilizers provided in Examples 1-8 to evaluate the performance of water-in-oil drilling fluid systems.

[0116] The sedimentation stability of the constructed oil-based drilling and completion fluid (which can also be used for oil-based drilling fluids) was evaluated using the sedimentation factor SF as an evaluation index.

[0117] Blank group formula: 3# white oil + 6% primary emulsifier + 2% secondary emulsifier + 3% organic clay + 5% CaO + 6% filtration loss reducer + calcium chloride aqueous solution (30% W / V) + barite, oil-water ratio 90:10, density 1.6 g / cm3.

[0118] Example formulation: blank group + 5% oil-based drilling and completion fluid suspension stabilizer.

[0119] Drilling fluids were prepared according to the formulas for the experimental and control groups described above. After aging at 220℃ for 16 hours, the fluids were placed in an aging vessel equipped with a high-temperature, high-pressure sedimentation stabilizer. Simulated bottomhole formation pressure of 100 MPa was applied, and the fluids were allowed to stand at high temperature for 15 days. The density difference between the upper and lower layers of the liquid in the aging vessel was measured, and the sedimentation factor SF was calculated. The experimental results are shown in Table 1.

[0120]

[0121] In the formula:

[0122] ρ 上 Density of drilling fluid at the top, g / cm3;

[0123] ρ 下 Density of drilling fluid at the bottom, g / cm3.

[0124] The liquid in the aging vessel was removed and stirred at high speed for 15 minutes. The YP and 6-turn readings at 220℃ / 100MPa were then measured using a high-temperature and high-pressure rheometer. The experimental results are shown in Table 2.

[0125] Table 1. Sedimentation Factors of Oil-Based Drilling Fluids in Examples

[0126]

[0127]

[0128] Table 2. High-Temperature and High-Pressure Rheological Properties of Oil-Based Drilling Fluids in Examples

[0129] sample YP / mPa·S 6 read values Blank group 9.5 12 Example 1 17 22 Example 2 16 21.5 Example 3 16.5 22 Example 4 17 22.5 Example 5 15.5 19 Example 6 17 22 Example 7 17 22 Example 8 17.5 23

[0130] According to the experimental results in Tables 1 and 2, the eight types of suspension stabilizers for oil-based drilling and completion fluids prepared in the embodiments of this invention can effectively control the settling factor of oil-based drilling and completion fluids at 220℃ / 15 days to ≤0.52, maintain high-temperature and high-pressure rheological properties (YP) ≥15Pa and 6-turn readings ≥20, thereby effectively improving suspension stability. Specifically, Example 2 increased the proportion of sepiolite and modifier, resulting in a slight decrease in suspension stability; Example 3 decreased the proportion of nano-silica and modifier, having a relatively small impact on the overall effect of the suspension stabilizer; Example 4 replaced the sepiolite modifier, having a relatively small impact on the overall effect of the suspension stabilizer; Example 5 replaced the nano-silica modifier, having a relatively small impact on the overall effect of the suspension stabilizer; Example 6 increased the reaction temperature, having a relatively small impact on the overall effect of the suspension stabilizer; Example 7 extended the reaction time, having a relatively small impact on the overall effect of the suspension stabilizer; and Example 8 increased the sepiolite mesh size, having a relatively small impact on the overall effect of the suspension stabilizer.

[0131] The various embodiments in this specification are described in a related manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on its differences from other embodiments. The above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A suspension stabilizer for oil-based drilling and completion fluids, characterized in that, The mixture includes modified sepiolite, modified nano-silica, and nano-calcium carbonate. The modified sepiolite is obtained by first modifying the sepiolite with a first silane coupling agent, and the modified nano-silica is obtained by second modifying the nano-silica with a second silane coupling agent.

2. The suspension stabilizer for oil-based drilling and completion fluids according to claim 1, characterized in that, The first modification process includes: The sepiolite was acid-treated with an acid solution to obtain acid-treated sepiolite. The acid-treated sepiolite was grafted using a first silane coupling agent.

3. The suspension stabilizer for oil-based drilling and completion fluids according to claim 2, characterized in that, In the grafting treatment, the pH is 9–12.

4. The suspension stabilizer for oil-based drilling and completion fluids according to claim 1, characterized in that, The second modification treatment includes: Nano-silica was modified using a second silane coupling agent – ​​an alcohol-water solution.

5. The suspension stabilizer for oil-based drilling and completion fluids according to any one of claims 1-4, characterized in that, The mass ratio of the modified sepiolite, the modified nano-silica, and the nano-calcium carbonate is (80-90):(10-20):(5-10).

6. The suspension stabilizer for oil-based drilling and completion fluids according to any one of claims 1-4, characterized in that, The first silane coupling agent is selected from at least one of n-octyltriethoxysilane, n-butyltriethoxysilane, and neopentyltriethoxysilane; and / or, The second silane coupling agent is selected from at least one of aminopropyltriethoxysilane, aminopropyltrimethoxysilane, and 2-aminoethyl-aminopropyltrimethoxysilane.

7. The suspension stabilizer for oil-based drilling and completion fluids according to any one of claims 1-4, characterized in that, The mass ratio of the sepiolite to the first silane coupling agent is (60-80):(30-40); and / or, The mass ratio of the nano-silica to the second silane coupling agent is (10-30):

1.

8. The suspension stabilizer for oil-based drilling and completion fluids according to any one of claims 1-4, characterized in that, The sepiolite has a particle size of at least one of 500, 1000, and 2000; and / or, The median particle size of the nano-silica is 50 nm; and / or, The nano-calcium carbonate has a particle size of 50 nm.

9. The suspension stabilizer for oil-based drilling and completion fluids according to any one of claims 1-4, characterized in that, In the first modification treatment, the reaction temperature is 70-90℃ and the time is 8-10h; and / or, In the second modification treatment, the reaction temperature is 50-80℃ and the time is 3-5h.

10. A method for preparing a suspension stabilizer for oil-based drilling and completion fluid according to any one of claims 1-9, characterized in that, Includes the following steps: The first modification treatment of sepiolite was carried out using a first silane coupling agent to obtain modified sepiolite. The nano-silica was subjected to a second modification treatment using a second silane coupling agent to obtain modified nano-silica. The modified sepiolite, the modified nano-silica, and the nano-calcium carbonate are mixed and treated to obtain the oil-based drilling and completion fluid suspension stabilizer.

Images