An oil-based drilling fluid stabilizer and its application

Abstract

The application provides an oil-based drilling fluid stabilizer and application thereof. The stabilizer comprises a graft structure with active silanol groups and ester groups, and is obtained through dehydration esterification reaction of a first reaction intermediate, a second reaction intermediate and a first catalyst under mixing and heating in a solvent; wherein the first reaction intermediate is prepared based on nano-laponite and gamma-aminopropyl triethoxysilane; and the second reaction intermediate is prepared based on oleic acid and triethanolamine. The stabilizer can slow down the influence of compressibility on drilling under the condition that the system maintains a relatively low oil-water ratio, and helps to improve emulsion stability and system sedimentation stability.

Description

Technical Field

[0001] This invention relates to an oil-based drilling fluid stabilizer and its application, belonging to the field of oilfield chemistry. Background Technology

[0002] In oil drilling, oil-based drilling fluids demonstrate significant advantages in deep and ultra-deep well development due to their excellent lubricity, inhibition properties, high-temperature and high-pressure stability, and strong anti-fouling capabilities. Oil-based drilling fluids possess high thermal stability, maintaining stable performance even at high temperatures, and exhibit strong resistance to salt and calcium contamination, making them suitable for complex formations. Their excellent lubrication properties reduce friction between the drill string and the wellbore, improving drilling efficiency. They effectively prevent water-sensitive effects on oil reservoirs, minimizing damage to oil and gas reservoirs.

[0003] The emulsion stability of oil-based drilling fluids is crucial for ensuring their overall performance. To maintain emulsion stability, emulsifiers are typically added, and wetting agents are added to increase the wettability of the solid material surface, thereby improving emulsion stability and system settling stability. To meet current requirements for oil-based drilling fluid emulsion stability, existing drilling fluid emulsion stabilizers ensure both stability in high oil-to-water ratio drilling fluid systems and good settling stability. Existing technology provides an oil-based drilling fluid settling stabilizer that uses organic cationic surfactants and nonionic terminal amine compounds to modify lithium-based bentonite and attapulgite. The prepared settling stabilizer forms a stable three-dimensional spatial network structure based on hydrophobically modified flake lithium-based bentonite and rod-shaped attapulgite, enabling it to address the poor solid particle suspension stability problem in high-temperature, high-pressure horizontal wells while maintaining low viscosity. The applicable oil-to-water ratio range is 80:20 to 95:5. The sedimentation factors of the prepared systems are all less than 0.53, indicating good stability.

[0004] However, there is still a severe shortage of oil-based drilling fluid emulsion stabilizers with low oil-water ratios, which cannot meet the requirements for stabilizing low oil-water ratio emulsions. Summary of the Invention

[0005] This invention provides an oil-based drilling fluid stabilizer and its application. The stabilizer can mitigate the impact of compressibility on drilling while maintaining a low oil-water ratio in the oil-based drilling fluid system, and improves emulsion stability and system sedimentation stability.

[0006] The stabilizer of this invention can enhance the oil-water interface film, prevent polymerization between emulsions, improve emulsion stability, and change the wettability of the solid phase surface. It forms a network structure in oil-based drilling fluid, increases the viscosity of the liquid phase, and keeps the solid particles uniformly distributed in the drilling fluid, thereby enhancing its settling stability.

[0007] In a first aspect, the present invention provides an oil-based drilling fluid stabilizer, the stabilizer comprising a grafted structure (X) having active silanol groups and ester groups;

[0008] The grafted structure (X) with active silanol groups and ester groups is as follows:

[0009]

[0010] Wherein, R is CH3(CH2)7CH=CH(CH2)7;

[0011] The stabilizer has the following structure:

[0012] A-(X)n

[0013] Where A is [Si8(Mg 5.34 Li 0.66 )O 20 [OH)3]Na 0.66 X is a grafted structure with active silanol groups and ester groups, and n refers to the number of X groups.

[0014] The stabilizer is obtained by mixing a first reaction intermediate, a second reaction intermediate, and a first catalyst in a solvent and heating them to carry out a dehydration esterification reaction;

[0015] The first reaction intermediate is prepared based on nano-lithium saponite and γ-aminopropyltriethoxysilane; the second reaction intermediate is prepared based on oleic acid and triethanolamine.

[0016] According to one embodiment of the present invention, the first reaction intermediate comprises a graft structure (N) with active silanol groups on nano-lithium saponite as follows:

[0017]

[0018] The structural formula of the first reaction intermediate is as follows:

[0019] A-(N)a

[0020] Where A is [Si8(Mg 5.34 Li 0.66 )O 20 [OH)3]Na 0.66 N represents a grafted structure with active silanol groups, and a refers to the number of N groups.

[0021] The first reaction intermediate was obtained by heating a mixed solution of nano-lithium saponite and an aqueous ethanol solution and then adding γ-aminopropyltriethoxysilane to react, thereby improving the nano-lithium saponite.

[0022] The second reaction intermediate includes an ester group, providing a polar group for the stabilizer; the structural formula of the second reaction intermediate is as follows:

[0023]

[0024] Wherein, R is CH3(CH2)7CH=CH(CH2)7;

[0025] The second reaction intermediate is obtained by heating a mixture of oleic acid and triethanolamine and then adding a second catalyst to carry out an esterification reaction.

[0026] According to one embodiment of the present invention, the first reaction intermediate accounts for 20% to 30% of the total reactants by mass.

[0027] According to one embodiment of the present invention, the second reaction intermediate accounts for 20% to 30% of the total reactants by mass.

[0028] According to one embodiment of the present invention, the mass percentage of nano-lithium saponite in the mixed solution is 2% to 5% of the mixed solution.

[0029] According to one embodiment of the present invention, the mass percentage of the γ-aminopropyltriethoxysilane is 15% to 25% of the mixed solution.

[0030] According to one embodiment of the present invention, the oleic acid in the mixture has a mass percentage content of 70%-80%.

[0031] According to one embodiment of the present invention, the first catalyst is one or more of aluminum oxide, copper oxide, and zinc oxide.

[0032] According to one embodiment of the present invention, the second catalyst is one or more of sulfuric acid, phosphoric acid, and hydrochloric acid.

[0033] Secondly, the present invention also provides an oil-based drilling fluid comprising the aforementioned stabilizer.

[0034] The drilling fluid of this invention includes the above-mentioned stabilizer, thus it can have high stability while maintaining a low oil-water ratio.

[0035] This invention provides an oil-based drilling fluid stabilizer and its application. The stabilizer comprises a grafted structure with active silanol groups and ester groups. The stabilizer in this invention is obtained by mixing and heating a first reaction intermediate, a second reaction intermediate, and a first catalyst. The first reaction intermediate is prepared based on nano-lithium saponite and γ-aminopropyltriethoxysilane; the second reaction intermediate is prepared based on oleic acid and triethanolamine. The first reaction intermediate is obtained by grafting and modifying nano-lithium saponite with γ-aminopropyltriethoxysilane, followed by esterification with triethanolamine to obtain the second reaction intermediate. The first and second reaction intermediates are then mixed and further dehydrated and esterified to obtain a dual-effect stabilizer suitable for low oil-water ratio oil-based drilling fluids. Because nano-lithium saponite is a two-dimensional nanostructure, its hydrophobicity is enhanced after modification, making it easy to disperse in oil-based drilling fluid systems. The special nanoscale layered structure of the modified nano-lithium saponite (i.e., the first reaction intermediate) can form a stable film at the oil-water interface, adsorbing at the oil-water interface, thus strengthening the oil-water interface film, preventing polymerization between emulsions, and keeping the emulsion stable at low oil-water ratios. Moreover, the modified nano-lithium saponite has a certain degree of wettability, changing the wetting effect of the solid surface of the system, improving the dispersion stability of solid particles in oil-based drilling fluids, reducing particle aggregation, thereby reducing sedimentation and improving the overall sedimentation stability of the drilling fluid. The stabilizer molecule structure of this invention has polar groups, which easily form hydrogen bonds within and between molecules, forming a three-dimensional network structure in the system, increasing the viscosity of the system, slowing down the sedimentation rate of solid particles, increasing the emulsion coagulation resistance, and enhancing the stability of the system. Attached Figure Description

[0036] Figure 1 A schematic diagram of the structure of a stabilizer provided by the present invention;

[0037] Figure 2 This is a schematic diagram illustrating the effect of WD1 on the sedimentation stability of emulsions with different oil-water ratios, provided by the present invention.

[0038] Figure 3 This is a schematic diagram illustrating the effect of WD1 on the TSI value of emulsions with different oil-water ratios, as provided by the present invention. Detailed Implementation

[0039] 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.

[0040] To maintain emulsion stability, emulsifiers are typically added to maintain emulsion stability, and wetting agents are added to increase the wettability of the solid material surface, thereby improving emulsion stability and system sedimentation stability. Current drilling fluid emulsion stabilizers ensure the stability of high oil-water ratio drilling fluid systems while also guaranteeing good sedimentation stability. However, emulsion stabilizers for low oil-water ratio oil-based drilling fluids are still very scarce and cannot meet the requirements for stability of low oil-water ratio emulsions.

[0041] The first aspect of the present invention provides an oil-based drilling fluid stabilizer, the stabilizer comprising a grafted structure (X) having active silanol groups and ester groups;

[0042] The graft structure (X) with active silanol groups and ester groups is as follows:

[0043]

[0044] Wherein, R is CH3(CH2)7CH=CH(CH2)7;

[0045] The stabilizer structure is as follows:

[0046] A-(X)n

[0047] Where A is [Si8(Mg 5.34 Li 0.66 )O 20 [OH)3]Na 0.66 X is a grafted structure with active silanol groups and ester groups, and n refers to the number of X groups.

[0048] The stabilizer is obtained by mixing and heating a first reaction intermediate, a second reaction intermediate, and a first catalyst.

[0049] The first reaction intermediate was prepared based on nano-lithium saponite and γ-aminopropyltriethoxysilane; the second reaction intermediate was prepared based on oleic acid and triethanolamine.

[0050] Before the dehydration esterification reaction, a first reaction intermediate and a second reaction intermediate need to be prepared. The first reaction intermediate is prepared based on nano-lithium saponite and γ-aminopropyltriethoxysilane. Nano-lithium saponite can rapidly swell in water to form a gel containing a large water network structure, exhibiting good thixotropic, dispersible, suspending, and thickening properties. However, nano-lithium saponite cannot be uniformly dispersed in oil-based drilling fluids, so it needs to be modified with γ-aminopropyltriethoxysilane to improve its performance. The second reaction intermediate contains polar groups, which can form a three-dimensional network structure in the oil phase, resulting in a weak gel structure in the emulsion or system, enhancing stability. The hydroxyl groups of triethanolamine can react with the amino groups on γ-aminopropyltriethoxysilane, and it has three active groups. The alkyl chain length of oleic acid has a corresponding hydrophobic effect, and triethanolamine can form three polar groups with oleic acid, making the network structure formed subsequently more stable. Therefore, the stabilizer prepared by this method can reduce the impact of compressibility on drilling while maintaining a low oil-water ratio in the drilling fluid system, and can simultaneously improve emulsion stability and system sedimentation stability.

[0051] According to further research by the inventors, the stabilizer is obtained by mixing and heating a first reaction intermediate, a second reaction intermediate, and a first catalyst in a solvent to carry out a dehydration esterification reaction. The preparation process includes: dispersing the first reaction intermediate in xylene, adding the second reaction intermediate, adjusting the pH to neutral, stirring and heating to 110-130°C, adding the first catalyst, reacting for 3-5 hours, and then adding diesel to dilute to obtain the stabilizer.

[0052] The first reaction intermediate is dispersed in xylene, followed by the addition of the second reaction intermediate. The pH is then adjusted to neutral to ensure reaction compatibility. The mixture is stirred and heated to 110–130°C. The first catalyst is added, and the catalytic reaction proceeds smoothly. The reaction is maintained at 110–130°C for 3–5 hours. Diesel fuel is then added to dilute the mixture and terminate any potential side reactions. The amount of diesel fuel used is the same as the theoretical product mass. The final product is a modified nano-lithium saponite dual-effect stabilizer with good emulsion stability and good system stability, suitable for oil-based drilling fluids with low oil-water ratios. Preferably, the stirring rate is 200–400 r / min.

[0053] It should be noted that water needs to be removed in time during the reaction to promote the forward reaction. The presence of water will cause the ester groups generated in the reaction to hydrolyze. The reaction ends when no more water is produced.

[0054] Among them, stabilizers with grafted structures containing active silanol and ester groups have polar groups that readily form hydrogen bonds intramolecularly and intermolecularly, creating a three-dimensional network structure in the system. This increases the system's viscosity, slows down the settling rate of solid particles, increases emulsion coagulation resistance, and enhances the system's stability. This stabilizer enables oil-based drilling fluid systems to maintain a low oil-water ratio, mitigates the impact of compressibility on drilling, and helps improve emulsion stability and system settling stability.

[0055] In one specific embodiment, the first reaction intermediate comprises a grafted structure (N) with active silanol groups on nanolithium saponite as follows:

[0056]

[0057] The structural formula of the first reaction intermediate is as follows:

[0058] A-(N)a

[0059] Where A is [Si8(Mg 5.34 Li 0.66 )O 20 [OH)3]Na 0.66 N represents a grafted structure with active silanol groups, and a refers to the number of N groups.

[0060] The first reaction intermediate was obtained by heating a mixed solution of nano-lithium saponite and an aqueous ethanol solution and then adding γ-aminopropyltriethoxysilane to react, thereby improving the nano-lithium saponite.

[0061] The second reaction intermediate includes an ester group, which provides the ester group for the stabilizer; the structural formula of the second reaction intermediate is as follows:

[0062]

[0063] Wherein, R is CH3(CH2)7CH=CH(CH2)7;

[0064] The second reaction intermediate is obtained by heating a mixture of oleic acid and triethanolamine and then adding a second catalyst to carry out an esterification reaction.

[0065] According to further research by the inventors, the preparation process of the first reaction intermediate includes: firstly, adding nano-lithium saponite to an aqueous solution of ethanol, thoroughly stirring the mixture of nano-lithium saponite and aqueous ethanol solution and dispersing it using ultrasound to obtain a uniform mixed solution, then heating the mixed solution to 40-60°C under stirring, then adding γ-aminopropyltriethoxysilane and reacting for 4-6 hours, after the reaction is completed, washing the product with anhydrous ethanol to ensure the uniformity of the first reaction intermediate, and finally drying to obtain the first reaction product.

[0066] Preferably, at a temperature of 20–30°C, the stirring time of the mixed solution is 5–10 min, the stirring rate is 200–400 r / min, and the ultrasonic dispersion time is 20–30 min.

[0067] Preferably, the washing with anhydrous ethanol is performed 3-4 times, the drying temperature is 50-70℃, and the drying time is 12-24 hours. The reactive functional group structure of the nano-lithium saponite is as follows:

[0068] B-Si-OH

[0069] Wherein, B is [Si7(Mg 5.34 Li 0.66 )O 20 [OH)3]Na 0.66 .

[0070] The structural formula of γ-aminopropyltriethoxysilane is as follows:

[0071]

[0072] Because nano-lithium saponite itself possesses excellent properties such as thixotropy, thickening, suspension, chemical stability, and adsorption, its hydrophobicity is further enhanced after modification with γ-aminopropyltriethoxysilane. The resulting stabilizer is easy to disperse in oil-based drilling fluid systems. The special nanoscale layered structure of the modified nano-lithium saponite can form a stable film at the oil-water interface, adsorbing at the oil-water interface, thereby strengthening the oil-water interface film, preventing polymerization between emulsions, and ensuring the stability of the emulsion under low oil-water ratio conditions.

[0073] Among them, the first reaction intermediate obtained by modifying nano-lithium saponite has significantly improved hydrophobicity, which can be dispersed in oil-based drilling fluid systems, so that the emulsion remains stable under low oil-water ratio conditions. In addition, the modified nano-lithium saponite has a certain degree of wettability, which reduces the agglomeration between particles and improves the settling stability of oil-based drilling fluid.

[0074] In one specific embodiment, the second reaction intermediate is obtained by heating a mixture of oleic acid and triethanolamine and then adding a second catalyst to carry out an esterification reaction. The preparation process of the second reaction intermediate includes: heating a mixture of oleic acid and triethanolamine and then adding a second catalyst to carry out an esterification reaction to obtain the second reaction intermediate.

[0075] Preferably, oleic acid and triethanolamine are mixed and heated to 150-175°C with stirring, wherein the stirring rate is preferably 200-400 r / min, and then a second catalyst is added to catalyze the esterification reaction. The reaction time is 4-6 h. During the reaction, water should be removed in time to promote the forward reaction. The presence of water will cause the ester group generated in the reaction to hydrolyze. The reaction ends when no water is produced, and the second reaction intermediate is obtained.

[0076] The structural formula of oleic acid is as follows:

[0077]

[0078] The structural formula of triethanolamine is as follows:

[0079]

[0080] The hydroxyl groups of triethanolamine can react with the amino groups on γ-aminopropyltriethoxysilane, and it has three active groups. The alkyl chain length of oleic acid has a corresponding hydrophobic effect, and triethanolamine can form three polar groups with oleic acid, making the network structure formed later more stable. The second reactive monomer prepared in this way hydrophobically modifies the nano-lithium saponite, making it dispersible in the oil phase. At the same time, after the lithium saponite is adsorbed on the surface of the emulsion in flake form, the polar groups in the second reactive monomer can form a three-dimensional network structure in the oil phase, which can form a weak gel structure in the emulsion or system, thus enhancing stability.

[0081] The second reaction intermediate is mainly a hydrophobic modification of nano-lithium saponite, which makes it dispersible in the oil phase. At the same time, after the lithium saponite is adsorbed on the surface of the emulsion in flake form, the polar groups in the second reaction monomer can form a three-dimensional network structure in the oil phase, which makes the emulsion or system form a weak gel structure and enhances stability.

[0082] In one specific embodiment, the mass fraction of the first reaction intermediate is 20% to 30%. For example, the mass fraction of the first reaction intermediate is a range consisting of any two of the following values: 20%, 22%, 24%, 26%, 28%, 30%.

[0083] In one specific embodiment, the mass fraction of the second reaction intermediate is 20% to 30%. For example, the mass fraction of the second reaction intermediate is a range consisting of any two of the following values: 20%, 23%, 25%, 27%, 30%.

[0084] In one specific embodiment, the solvent may be xylene, wherein the mass fraction of xylene is 40% to 60%, for example, the mass fraction of xylene is 40%, 42%, 45%, 48%, 50%, 55%, 60% or any two of the above values.

[0085] In one specific embodiment, the mass fraction of nano-lithium saponite in the mixed solution is 2% to 5%. For example, the mass fraction of nano-lithium saponite in the mixed solution is a range consisting of any two of the following values: 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%.

[0086] Preferably, the mass fraction of ethanol in the mixed solution is 20% to 25%. For example, the mass fraction of ethanol in the mixed solution is any two of the following values: 20%, 21%, 22%, 23%, 24%, 25%. The mass fraction of pure water in the mixed solution is 70% to 80%. For example, the mass fraction of pure water in the mixed solution is any two of the following values: 70%, 72%, 74%, 76%, 78%, 80%.

[0087] In one specific embodiment, the mass percentage of γ-aminopropyltriethoxysilane is 15%-25%. For example, the mass percentage of γ-aminopropyltriethoxysilane is 15%, 17%, 19%, 21%, 23%, 25%, or any two of the above values.

[0088] In one specific embodiment, the mass percentage of oleic acid in the mixture is 70%-80%. For example, the mass percentage of oleic acid in the mixture is a range consisting of any two of the following values: 70%, 72%, 74%, 76%, 78%, 80%.

[0089] In one specific embodiment, the present invention does not specifically limit the type of the first catalyst. Preferably, the first catalyst includes, but is not limited to, one or more of aluminum oxide, copper oxide, and zinc oxide.

[0090] In one specific embodiment, the present invention does not specifically limit the type of the second catalyst. In a preferred embodiment, the second catalyst includes, but is not limited to, one or more of sulfuric acid, phosphoric acid, and hydrochloric acid.

[0091] A second aspect of the present invention provides an oil-based drilling fluid prepared according to the method described in the first aspect above.

[0092] This invention does not limit the composition of drilling fluid to other components, and can be a water-in-oil system drilling fluid commonly used in the art.

[0093] In practical applications, the stabilizer is added at a mass percentage of 1%-2%.

[0094] The following specific embodiments will provide a detailed description of the oil-based drilling fluid stabilizer, its preparation method, and its application provided by the present invention.

[0095] 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.

[0096] Figure 1 A schematic diagram of the structure of a stabilizer provided by the present invention. For example... Figure 1 As shown, in stabilizer A-(X)n, n=1, that is, it includes a grafted structure with active silanol groups and ester groups.

[0097] Example 1

[0098] The preparation process of the stabilizer in this embodiment includes the following steps:

[0099] 1) First, add 5g of nano lithium soapstone to 95g of ethanol aqueous solution (ethanol:water = 1:4), ultrasonically disperse the mixed solution for 30min, then stir for 5min, and control the temperature at 25℃.

[0100] 2) After stirring and heating the mixed solution from step 1 to 55°C at 300 r / min, add 30 g of γ-aminopropyltriethoxysilane and react for 5 h. Wash three times with anhydrous ethanol and dry at 60°C for 24 h to obtain the first reaction intermediate.

[0101] 3) Mix 56.5g of oleic acid with 15g of triethanolamine, stir and heat to 165℃ at 300r / min, add 5g of phosphoric acid to carry out esterification reaction for 5h, remove water in time, and after no water is produced, the second reaction intermediate is obtained.

[0102] 4) Disperse 33g of the first reaction intermediate in 60g of xylene, then add 37g of the second reaction intermediate, adjust the pH to neutral, stir and heat to 125℃, add 5g of aluminum oxide, react for 4h, remove water in time, and after no water is produced, the reaction is over, add 100g of diesel oil to dilute, and obtain stabilizer WD1.

[0103] Table 1 shows the designed examples and comparative experiments. Wherein, m1 is the mass of nano-lithium saponite, m2 is the mass of γ-aminopropyltriethoxysilane, m3 is the mass of the first reaction intermediate, m4 is the mass of oleic acid, and m5 is the mass of the second reaction intermediate.

[0104] Table 1

[0105]

[0106]

[0107] The formula for calculating the mass percentage of nano-lithium saponite is as follows:

[0108]

[0109] The formula for calculating the mass percentage of γ-aminopropyltriethoxysilane is as follows:

[0110]

[0111] The formula for calculating the mass percentage of the first reaction intermediate is as follows:

[0112]

[0113] The formula for calculating the mass percentage of the second reaction intermediate is as follows:

[0114]

[0115] The formula for calculating the mass percentage of oleic acid is as follows:

[0116]

[0117] Among them, WD1-WD11 are stabilizers with different numbers of grafted structures, and products 1-10 are comparative products.

[0118] Experimental Example 1

[0119] Prepare emulsions with different oil-to-water ratios, and then add an equal amount of stabilizer WD1 to the emulsions. Observe and measure the stability of the emulsions respectively.

[0120] Sample 1: 1.5g Span80 + 11mL diesel oil + 9mL 20% calcium chloride saline + 0.2g WD1;

[0121] Sample 2: 1.5g Span80 + 12mL diesel oil + 8mL 20% calcium chloride saline + 0.2g WD1;

[0122] Sample 3: 1.5g Span80 + 13mL diesel oil + 7mL 20% calcium chloride saline + 0.2g WD1;

[0123] Sample 4: 1.5g Span80 + 14mL diesel oil + 6mL 20% calcium chloride saline + 0.2g WD1;

[0124] Sample 5: 1.5g Span80 + 15mL diesel oil + 5mL 20% calcium chloride saline + 0.2g WD1.

[0125] The prepared emulsion was left to stand at room temperature for 24 hours. By comparing the stability of the emulsion under different oil-water ratios, it was found that the emulsion was relatively stable when the oil-water ratio was higher than 60:40. However, when the oil-water ratio was 55:45, obvious oil-water separation was observed. Figure 2 The diagram shows the effect of WD1 on the sedimentation stability of emulsions with different oil-water ratios, as provided by this invention. Figure 3 The graph shows the effect of WD1 on the TSI value of emulsions with different oil-water ratios, as provided by this invention. The results are as follows: Figure 2 and Figure 3 As shown, the stabilizer provided by the present invention can achieve good emulsion stabilization under conditions where the oil-water ratio is higher than 60:40.

[0126] Electrical stability test before and after aging: The oil-based drilling fluid was stirred at 12000 r / min for 20 min. The demulsification voltage before and after aging was determined according to GB / T16783.2-2012. The experimental results are shown in Table 2.

[0127] Table 2

[0128]

[0129]

[0130] As shown in Table 2, the demulsification voltage (ES) before aging was 2000+, and the demulsification voltage decreased after aging, indicating that the emulsifier's emulsification effect deteriorated after aging. However, in the system with the stabilizer provided by this invention, the demulsification voltage was greater than 1#.

[0131] In Table 2, the ES value of drilling fluid with WD1 added after aging is 1647, while the ES value of drilling fluid with WD2-WD11 added after aging is between 1025 and 1258. In contrast, the ES value of drilling fluid with products 1-10 added after aging is between 671 and 778. This indicates that the effect of adding stabilizers WD1-WD11 is significantly higher than that of products 1-10, with stabilizer WD1 showing a more pronounced effect. This is because the nanoscale layered structure in the stabilizer can form a stable film at the oil-water interface, adsorbing onto the interface and strengthening the interfacial film. This makes it more difficult for oil and water to mix at the oil-water interface, thus improving emulsion stability.

[0132] Static sedimentation test after aging: The above stabilizer and product were subjected to a static sedimentation test after aging. After aging, the mixture was stirred at 10000 r / min for 20 min and then left to stand in an oven at 180℃ for 24 h. The density ρ of the upper part of the drilling fluid column was then measured. top and the density ρ of the lower part of the drilling fluid bottom The static settling factor of drilling fluid is calculated using the following formula.

[0133]

[0134] SF—Sedimentation factor, dimensionless;

[0135] ρ top —Density of the upper part of the drilling fluid column (lower layer of free fluid), g / cm³ 3 ;

[0136] ρ bottom —Drilling fluid column bottom density, g / cm³ 3 ;

[0137] The calculation result is expressed to 4 significant digits.

[0138] The experimental results are shown in Table 3.

[0139] Table 3

[0140] Serial Number 1# 2# 3# 4# 5# 6# 7# 8# SF 0.5307 0.5009 0.5078 0.5077 0.5284 0.5256 0.5087 0.5063

[0141] Table 3 (continued)

[0142] Serial Number 9# 10# 11# 12# 13# 14# 15# 16# SF 0.5241 0.5307 0.5019 0.5078 0.5277 0.5284 0.5056 0.5087

[0143] Table 3 (continued)

[0144]

[0145]

[0146] In Table 3, #1 represents the SF value of the basic drilling fluid formulation (i.e., the comparative experiment without stabilizers and products), which is 0.5307. #2-4 represent the SF values ​​after adding stabilizers WD1-WD3 to the drilling fluid, respectively. #5-6 represent the SF values ​​after adding products 1-2 to the drilling fluid, respectively. #7-8 represent the SF values ​​after adding stabilizers WD4-WD5 to the drilling fluid, respectively. #9-10 represent the SF values ​​after adding products 3-4 to the drilling fluid, respectively. #11-12 represent the SF values ​​after adding stabilizers WD4-WD5 to the drilling fluid, respectively. The SF values ​​after adding stabilizers WD6-WD7 to the drilling fluid are as follows: #13-14# are the SF values ​​after adding products 5-6 to the drilling fluid, respectively; #15-16# are the SF values ​​after adding stabilizers WD8-WD9 to the drilling fluid, respectively; #17-18# are the SF values ​​after adding products 7-8 to the drilling fluid, respectively; #19-20# are the SF values ​​after adding stabilizers WD10-WD11 to the drilling fluid, respectively; and #21-22# are the SF values ​​after adding products 9-10 to the drilling fluid, respectively.

[0147] Among them, the SF values ​​of stabilizers WD1-WD11 ranged from 0.5009 to 0.5087, and the SF values ​​of products 1-10 ranged from 0.5263 to 0.5307. Among them, the SF value of WD1 added to product #2 (0.5009) was the best, and the SF values ​​of WD2-WD11 added were better than those of products 1-10, indicating that the addition of stabilizers had a better effect on static sedimentation stabilization.

[0148] A SF value of 0.5 indicates that no sedimentation occurred in the oil-based drilling fluid system under these conditions, while a SF value > 0.52 indicates poor static sedimentation stability of the oil-based drilling fluid under these conditions. Table 3 shows that the drilling fluid (1#) without stabilizer exhibited poor static sedimentation stability after high-temperature aging, with an SF value of 0.5307. After adding stabilizers (WD1-WD11), the static sedimentation stability of the drilling fluid improved significantly, with SF values ​​ranging from 0.5009 to 0.5087 in Table 3. The SF value (0.5009) of 2# with WD1 was the optimal value. Drilling fluids with added products 1-10 had SF values ​​ranging from 0.5263 to 0.5307, indicating that the static sedimentation effect of drilling fluids with added products 1-10 was better than or equal to that of the comparative experiment. This also demonstrates that the static sedimentation stability of the dual-effect stabilizer system with a physicochemical three-dimensional network structure was better.

[0149] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An oil-based drilling fluid stabilizer, characterized in that, The stabilizer comprises a grafted structure (X) having active silanol groups and ester groups; The grafted structure (X) with active silanol groups and ester groups is as follows: Wherein, R is CH3(CH2)7CH=CH(CH2)7; The stabilizer has the following structure: A-(X)n Where A is [Si8(Mg 5.34 Li 0.66 )O 20 [OH)3]Na 0.66 X is a grafted structure with active silanol groups and ester groups, and n refers to the number of X groups. The stabilizer is obtained by mixing a first reaction intermediate, a second reaction intermediate, and a first catalyst in a solvent and heating them to carry out a dehydration esterification reaction; The first reaction intermediate is prepared based on nano-lithium saponite and γ-aminopropyltriethoxysilane; the second reaction intermediate is prepared based on oleic acid and triethanolamine.

2. The stabilizer according to claim 1, characterized in that, The first reaction intermediate comprises a grafted structure (N) with active silanol groups on nano-lithium saponite, as follows: The structural formula of the first reaction intermediate is as follows: A-(N)a Where A is [Si8(Mg 5.34 Li 0.66 )O 20 [OH)3]Na 0.66 N represents a grafted structure with active silanol groups, and a refers to the number of N groups. The first reaction intermediate was obtained by heating a mixed solution of nano-lithium saponite and an aqueous ethanol solution and then adding γ-aminopropyltriethoxysilane to react, thereby improving the nano-lithium saponite. The second reaction intermediate includes an ester group, providing a polar group for the stabilizer; the structural formula of the second reaction intermediate is as follows: Wherein, R is CH3(CH2)7CH=CH(CH2)7; The second reaction intermediate is obtained by heating a mixture of oleic acid and triethanolamine and then adding a second catalyst to carry out an esterification reaction.

3. The stabilizer according to claim 2, characterized in that, The first reaction intermediate accounts for 20% to 30% of the total reactants by mass.

4. The stabilizer according to claim 2, characterized in that, The second reaction intermediate accounts for 20% to 30% of the total reactants by mass.

5. The stabilizer according to claim 2, characterized in that, The mass percentage of nano-lithium saponite in the mixed solution is 2% to 5%.

6. The stabilizer according to claim 2, characterized in that, The mass percentage of the γ-aminopropyltriethoxysilane is 15% to 25% of the mixed solution.

7. The stabilizer according to claim 2, characterized in that, The oleic acid content in the mixture is 70%-80% by mass.

8. The stabilizer according to claim 1, characterized in that, The first catalyst is one or more of aluminum oxide, copper oxide, and zinc oxide.

9. The stabilizer according to claim 2, characterized in that, The second catalyst is one or more of sulfuric acid, phosphoric acid, and hydrochloric acid.

10. An oil-based drilling fluid, characterized in that, The drilling fluid contains the stabilizer as described in claims 1 to 7.

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