Tackifying and shear strength improving agent, preparation method thereof and oil-based drilling fluid containing tackifying and shear strength improving agent

Abstract

The invention provides a tackifying and shear strength improving agent, a preparation method thereof and an oil-based drilling fluid containing the tackifying and shear strength improving agent. The preparation method comprises the following steps: mixing a first surfactant, montmorillonite and rectorite, and carrying out a first reaction to obtain a first reaction intermediate; mixing the first reaction intermediate with a second surfactant, and carrying out a second reaction to obtain a second reaction intermediate; mixing the second reaction intermediate with a fluorine-containing quaternary ammonium salt surfactant, and carrying out a third reaction to obtain a third reaction intermediate; and mixing the third reaction intermediate with a silane coupling agent modified nano material under an alkaline condition, and carrying out a fourth reaction to obtain the tackifying and shear strength improving agent for the oil-based drilling fluid. The obtained tackifying and shear strength improving agent is used for the oil-based drilling fluid, and has excellent tackifying and shear strength improving effects and ultrahigh temperature resistance.

Description

Technical Field

[0001] This invention belongs to the technical field of oil-based drilling fluids for petroleum drilling, specifically a viscosity-enhancing and shear-lifting agent, its preparation method, and an oil-based drilling fluid containing the same. Background Technology

[0002] Deep and ultra-deep wells face severe challenges such as high temperature, high pressure, and high water cut. Organic clays used in oil-based drilling fluids often experience surface modifier desorption or self-pyrolysis due to high temperatures, further deteriorating the system's rheological properties. Currently, organic clays in oil-based drilling fluids generally lack sufficient temperature resistance, making it difficult to maintain rheological stability at 260℃. After failure, they become inferior solid phases, severely affecting the system's rheological properties. Therefore, researching viscosity enhancers and shearing agents for oil-based drilling fluids with ultra-high temperature resistance is of profound significance for the development of oil-based drilling fluid technology in deep and ultra-deep wells and for the exploration and development of deep and ultra-deep oil and gas formations.

[0003] CN109266318B discloses a water-based drilling fluid anti-high temperature viscosity-enhancing and shearing agent, its preparation method, and the drilling fluid thereof. The viscosity-enhancing and shearing agent is prepared through the following steps: starch is added to 100-200g of an alkaline solution with a concentration of 0.1-0.4mol / L to form a dispersion; the dispersion is stirred at high speed at 30-60℃ until all the starch is dissolved; then a crosslinking agent is added, and after thorough mixing and standing, the aqueous phase is separated from the mixture; 2-8g of emulsifier and 50-150g of organic solvent are added to the aqueous phase; a white emulsion is obtained. The emulsion was stirred at high speed (5000-20000 rpm) at 35-45℃ for about 10 minutes, and then stirred at low speed (200-1000 rpm) at room temperature for about 20 hours. After the reaction was complete, the emulsion was transferred to a separatory funnel and the aqueous phase containing starch microgels was separated using an extractant. The resulting aqueous product was centrifuged to separate the solid phase, and washed repeatedly with deionized water and ethanol several times before being vacuum dried at 60℃ for 16 hours to finally obtain starch microgels. This thickening and shearing agent exhibited good thickening and shearing effects at 150℃, but its high-temperature resistance still needs improvement. CN115572347B discloses a high-temperature and high-salt resistant thickening and shearing agent for water-based drilling fluids, its preparation method, and its application. It improves high-temperature resistance by adding 2-acrylamido-2-methylpropanesulfonic acid, sodium styrene sulfonate, or sodium vinyl sulfonate, which are temperature and salt resistant monomers. The thickening and cutting agent exhibits good thickening and cutting effects at 200℃, but its high-temperature resistance still needs improvement.

[0004] In summary, the high-temperature resistance of existing thickening and cutting agents still needs improvement. Therefore, it is necessary to provide a new thickening and cutting agent to address the aforementioned issues. Summary of the Invention

[0005] To address the aforementioned technical problems, the present invention aims to provide a viscosity-enhancing and shearing agent, its preparation method, and an oil-based drilling fluid containing the same. This viscosity-enhancing and shearing agent, when used in oil-based drilling fluids, exhibits excellent viscosity-enhancing and shearing effects as well as resistance to ultra-high temperatures.

[0006] To achieve the above objectives, the present invention provides a method for preparing a viscosity-enhancing and cutting agent for oil-based drilling fluids, comprising the following steps: The first surfactant, montmorillonite, and retinoic acid are mixed and subjected to a first reaction to obtain a first reaction intermediate. The first reaction intermediate and the second surfactant are mixed to carry out a second reaction to obtain the second reaction intermediate; The second reaction intermediate and the fluorinated quaternary ammonium salt surfactant are mixed and subjected to a third reaction to obtain the third reaction intermediate; The third reaction intermediate was mixed with silane coupling agent-modified nanomaterials under alkaline conditions to carry out the fourth reaction, thereby obtaining a viscosity enhancer and shearing agent for oil-based drilling fluids. The first surfactant is selected from one or more of tetramethylammonium bromide, tetrabutylammonium bromide, and trimethylbenzylammonium bromide; the second surfactant is selected from one or more of dodecyltrimethylammonium bromide, hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, and bis(octadecyltrimethylammonium chloride).

[0007] This invention first uses a first surfactant and a second surfactant to intercalate and modify montmorillonite and rettore, then introduces a fluorinated quaternary ammonium salt surfactant for further intercalation and modification, and finally introduces a silane coupling agent to modify nanomaterials for further grafting modification, thus obtaining a viscosity-enhancing and shearing agent for oil-based drilling fluids, which has excellent viscosity-enhancing and shearing effects as well as resistance to ultra-high temperatures.

[0008] In some alternative embodiments, montmorillonite and montmorillonite are commercially available mineral clays with activated functional groups such as carboxyl and hydroxyl groups on their surface.

[0009] Furthermore, the fluorinated quaternary ammonium salt surfactant is selected from one or more combinations of perfluorooctyl sulfonic acid ethyl quaternary ammonium salt, perfluorooctyl quaternary ammonium iodide, and perfluorooctyl carboxylic acid quaternary ammonium salt iodide.

[0010] Furthermore, the silane coupling agent modified nanomaterials are selected from one or more combinations of KH-570 modified nano-silica, KH-570 modified nano-titanium dioxide, KH550 modified nano-silica, and KH550 modified nano-titanium dioxide.

[0011] The amounts of montmorillonite, levainite, the first surfactant, the second surfactant, the fluorinated quaternary ammonium salt surfactant, and the silane coupling agent-modified nanomaterials can be adjusted appropriately according to the desired thickening and shearing effect. In some optional embodiments, the weight ratio of montmorillonite to levainite is 60-80:40-20, for example, 70:30. The molar ratio of the first surfactant, the second surfactant, the fluorinated quaternary ammonium salt surfactant, and the silane coupling agent-modified nanomaterials (based on nanomaterials) is 0.5-1.5:0.1-1.0:0.05-0.5:0.1-1.5, preferably 0.75-1.25:0.25-0.75:0.1-0.4:0.5-1.0.

[0012] In some alternative embodiments, the temperature of the first reaction is 40~70°C, the time is 3~5h, and the stirring speed is 350~450r / min.

[0013] In some alternative embodiments, the temperature of the second reaction is 50~80°C, the time is 4~8h, and the stirring speed is 350~450r / min.

[0014] In some alternative embodiments, the temperature of the third reaction is 70~90°C, the time is 10~14h, and the stirring speed is 350~450r / min.

[0015] In some alternative embodiments, the temperature of the fourth reaction is 80~100℃, the time is 6~10h, and the stirring speed is 350~450r / min.

[0016] The present invention also provides a viscosity enhancer and shearing agent for oil-based drilling fluids, which is prepared by the aforementioned preparation method.

[0017] The present invention also provides an oil-based drilling fluid comprising the aforementioned viscosity-enhancing and shear-lifting agent. The viscosity-enhancing and shear-lifting agent is used to regulate the viscosity and shear rate of the oil-based drilling fluid.

[0018] According to a specific embodiment of the present invention, preferably, the amount of thickening and shearing agent used is 0.5 to 2.5% of the weight of the oil-based drilling fluid.

[0019] In some alternative embodiments, the oil phase of the oil-based drilling fluid can be provided by an oil phase conventionally used in the art, such as diesel oil and / or white oil, preferably No. 3 white oil (flash point 220°C, kinematic viscosity 3 mmHg at 40°C). 2 / s, specific gravity 0.85) or No. 5 white oil (flash point 220℃, kinematic viscosity 3.5mm at 40℃) 2 / s, specific gravity is 0.85); the aqueous phase can be an aqueous solution of CaCl2, preferably an aqueous solution of CaCl2 with a mass concentration of 20~40%. The volume ratio of the oil phase to the aqueous phase is (80~90):(20~10).

[0020] According to a specific embodiment of the present invention, preferably, the aging temperature of the oil-based drilling fluid is 260°C. The viscosity-enhancing and shear-lifting agent of the present invention can effectively stabilize the viscosity and shear of oil-based drilling fluids at high temperatures above 260°C, meeting the actual drilling needs of deep and ultra-deep wells.

[0021] In some alternative embodiments, the oil-based drilling fluid may also contain other processing agents conventionally used in the art, such as one or more combinations of emulsifiers, filtration reducers, plugging agents, alkalinity adjusters, and weighting agents. The aforementioned processing agents can be selected according to conventional types and dosages in the art, and the present invention does not particularly limit their use. Detailed Implementation

[0022] In order to provide a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention will now be described in detail below, but it should not be construed as limiting the scope of implementation of the present invention.

[0023] Example 1

[0024] This embodiment provides a thickening and cutting agent, the preparation method of which includes the following steps: First, 70g of montmorillonite (purchased from Shanghai Wanzhao Fine Chemical Co., Ltd.) and 30g of montmorillonite (purchased from Shanghai Wanzhao Fine Chemical Co., Ltd.) were dispersed in water and stirred at 350r / min for 30min. Then, 115g of tetramethylammonium bromide was added, and the temperature was raised to 40℃ for 3h. Next, 87g of dioctadecyldimethylammonium chloride was added, and the temperature was raised to 50℃, while stirring at 350r / min for 4h. Then, 72.5g of perfluorooctyl quaternary ammonium salt (CAS No. 56773-42-3) was added, and the temperature was raised to 70℃, while stirring at 350r / min for 10h. Finally, 147g of KH-570 modified nano-silica (purchased from Hangzhou Jikang New Materials Co., Ltd.) was added, and the temperature was raised to 80℃, while stirring at 350r / min for 6h to obtain the product, oil-based drilling fluid viscosity enhancer and shearing agent KRM-1. The molar ratio of the first surfactant, the second surfactant, the fluorinated quaternary ammonium salt surfactant, and the silane coupling agent modified nanomaterial is 0.75:0.15:0.1:0.5.

[0025] Example 2

[0026] This embodiment provides a thickening and cutting agent, the preparation method of which includes the following steps: First, 70g of montmorillonite and 30g of retinoic acid were dispersed in water and stirred at 350 rpm for 30 min. Then, 154g of tetramethylammonium bromide was added, and the temperature was raised to 50℃ for 4 h. Next, 174g of dioctadecyldimethylammonium chloride was added, and the temperature was raised to 60℃, while stirring at 350 rpm for 6 h. Then, 72.5g of perfluorooctyl quaternary ammonium salt (CAS No. 56773-42-3) was added, and the temperature was raised to 70℃, while stirring at 350 rpm for 10 h. Finally, 147g of KH-570 modified nano-silica was added, and the temperature was raised to 80℃, while stirring at 350 rpm for 6 h, yielding the product, oil-based drilling fluid viscosity enhancer and shearing agent KRM-2. The molar ratio of the first surfactant, the second surfactant, the fluorinated quaternary ammonium salt surfactant, and the silane coupling agent-modified nanomaterial was 1:0.3:0.1:0.5.

[0027] Example 3

[0028] This embodiment provides a thickening and cutting agent, the preparation method of which includes the following steps: First, 70g of montmorillonite and 30g of retinoic acid were dispersed in water and stirred at 350 rpm for 30 min. Then, 154g of tetramethylammonium bromide was added, and the temperature was raised to 50℃ for 4 h. Next, 174g of dioctadecyldimethylammonium chloride was added, and the temperature was raised to 60℃, while stirring at 350 rpm for 6 h. Then, 145g of perfluorooctyl quaternary ammonium salt (CAS No. 56773-42-3) was added, and the temperature was raised to 80℃, while stirring at 350 rpm for 12 h. Finally, 220g of KH-570 modified nano-silica was added, and the temperature was raised to 90℃, while stirring at 350 rpm for 8 h, yielding the product, oil-based drilling fluid viscosity enhancer and shearing agent KRM-3. The molar ratio of the first surfactant, the second surfactant, the fluorinated quaternary ammonium salt surfactant, and the silane coupling agent-modified nanomaterial was 1:0.3:0.2:0.75.

[0029] Example 4

[0030] This embodiment provides a thickening and cutting agent, the preparation method of which includes the following steps: First, 70g of montmorillonite and 30g of retinoic acid were dispersed in water and stirred at 350 rpm for 30 min. Then, 192g of tetramethylammonium bromide was added, and the temperature was raised to 70℃ for 5 h. Next, 261g of dioctadecyldimethylammonium chloride was added, and the temperature was raised to 80℃, while stirring at 350 rpm for 8 h. Then, 145g of perfluorooctyl quaternary ammonium salt (CAS No. 56773-42-3) was added, and the temperature was raised to 80℃, while stirring at 350 rpm for 12 h. Finally, 220g of KH-570 modified nano-silica was added, and the temperature was raised to 90℃, while stirring at 350 rpm for 8 h, yielding the product, oil-based drilling fluid viscosity enhancer and shearing agent KRM-4. The molar ratio of the first surfactant, the second surfactant, the fluorinated quaternary ammonium salt surfactant, and the silane coupling agent-modified nanomaterial was 1.25:0.45:0.2:0.75.

[0031] Example 5

[0032] This embodiment provides a thickening and cutting agent, the preparation method of which includes the following steps: First, 70g of montmorillonite and 30g of retinoic acid were dispersed in water and stirred at 350 rpm for 30 min. Then, 192g of tetramethylammonium bromide was added, and the temperature was raised to 70℃ for 5 h. Next, 261g of dioctadecyltrimethylammonium chloride was added, and the temperature was raised to 80℃, while stirring at 350 rpm for 8 h. Then, 290g of perfluorooctyl quaternary ammonium salt (CAS No. 56773-42-3) was added, and the temperature was raised to 80℃, while stirring at 350 rpm for 12 h. Finally, 294g of KH-570 modified nano-silica was added, and the temperature was raised to 100℃, while stirring at 350 rpm for 10 h, yielding the product, oil-based drilling fluid viscosity enhancer and shearing agent KRM-5. The molar ratio of the first surfactant, the second surfactant, the fluorinated quaternary ammonium salt surfactant, and the silane coupling agent-modified nanomaterial was 1.25:0.45:0.4:1.

[0033] Example 6

[0034] This embodiment provides a thickening and cutting agent, the preparation method of which includes the following steps: First, 70g of montmorillonite and 30g of retinoic acid were dispersed in water and stirred at 350 rpm for 30 min. Then, 154g of tetramethylammonium bromide was added, and the temperature was raised to 50℃ for 4 h. Next, 92.4g of dodecyltrimethylammonium bromide was added, and the temperature was raised to 60℃, while stirring at 350 rpm for 6 h. Then, 145g of perfluorooctyl quaternary ammonium salt (CAS No. 56773-42-3) was added, and the temperature was raised to 80℃, while stirring at 350 rpm for 12 h. Finally, 220g of KH-570 modified nano-silica was added, and the temperature was raised to 90℃, while stirring at 350 rpm for 8 h, yielding the product, oil-based drilling fluid viscosity enhancer and shearing agent KRM-6. The molar ratio of the first surfactant, the second surfactant, the fluorinated quaternary ammonium salt surfactant, and the silane coupling agent-modified nanomaterial was 1:0.3:0.2:0.75.

[0035] Example 7

[0036] This embodiment provides a thickening and cutting agent, the preparation method of which includes the following steps: First, 70g of montmorillonite and 30g of retinoic acid were dispersed in water and stirred at 350 rpm for 30 min. Then, 154g of tetramethylammonium bromide was added, and the temperature was raised to 50℃ for 4 h. Next, 109g of hexadecyltrimethylammonium bromide was added, and the temperature was raised to 60℃, while stirring at 350 rpm for 6 h. Then, 145g of perfluorooctyl quaternary ammonium salt (CAS No. 56773-42-3) was added, and the temperature was raised to 80℃, while stirring at 350 rpm for 12 h. Finally, 220g of KH-570 modified nano-silica was added, and the temperature was raised to 90℃, while stirring at 350 rpm for 8 h, yielding the product, oil-based drilling fluid viscosity enhancer and shearing agent KRM-7. The molar ratio of the first surfactant, the second surfactant, the fluorinated quaternary ammonium salt surfactant, and the silane coupling agent-modified nanomaterial was 1:0.3:0.2:0.75.

[0037] Example 8

[0038] This embodiment provides a thickening and cutting agent, the preparation method of which includes the following steps: First, 70g of montmorillonite and 30g of retinoic acid were dispersed in water and stirred at 350 rpm for 30 min. Then, 154g of tetramethylammonium bromide was added, and the temperature was raised to 50℃ for 4 h. Next, 96g of hexadecyltrimethylammonium chloride was added, and the temperature was raised to 60℃, while stirring at 350 rpm for 6 h. Then, 145g of perfluorooctyl quaternary ammonium salt (CAS No. 56773-42-3) was added, and the temperature was raised to 80℃, while stirring at 350 rpm for 12 h. Finally, 220g of KH-570 modified nano-silica was added, and the temperature was raised to 90℃, while stirring at 350 rpm for 8 h, yielding the product, oil-based drilling fluid viscosity enhancer and shearing agent KRM-7. The molar ratio of the first surfactant, the second surfactant, the fluorinated quaternary ammonium salt surfactant, and the silane coupling agent-modified nanomaterial was 1:0.3:0.2:0.75.

[0039] Comparative Example 1

[0040] This comparative example provides a thickening and cutting agent, the preparation method of which differs from that of Example 3 only in that: no second surfactant and fluorinated quaternary ammonium salt surfactant are added, resulting in the product thickening and cutting agent DRM-1.

[0041] Comparative Example 2

[0042] This comparative example provides a thickening and cutting agent, the only difference between its preparation method and that of Example 3 is that the first surfactant and silane coupling agent were not added to modify the nanomaterials, resulting in the product thickening and cutting agent DRM-2.

[0043] Comparative Example 3

[0044] This comparative example provides a thickening and cutting agent, the preparation method of which differs from that of Example 3 only in that the raw materials are simply mixed without reaction, yielding the product thickening and cutting agent DRM-3. Specifically, it includes the following steps: 70g montmorillonite, 30g levaline, 154g tetramethylammonium bromide, 174g dioctadecyldimethylammonium chloride, 145g perfluorooctyl quaternary ammonium salt (CAS No. 56773-42-3), 220g KH-570 modified nano-silica, and water were stirred at 350r / min for 30min until homogeneous, yielding the thickening and shearing agent DRM-3. The molar ratio of the first surfactant, the second surfactant, the fluorinated quaternary ammonium salt surfactant, and the silane coupling agent-modified nanomaterial was 1:0.3:0.2:0.75.

[0045] Comparative Example 4

[0046] This comparative example provides a thickening and cutting agent, the preparation method of which differs from that of Example 3 only in that: the amount of tetramethylammonium bromide is 62g, the amount of dioctadecyldimethylammonium chloride is 17g, the amount of perfluorooctyl quaternary ammonium salt is 18g, and the amount of KH-570 modified nano-silica is 55g, yielding the product thickening and cutting agent DRM-4. The molar ratio of the first surfactant, the second surfactant, the fluorinated quaternary ammonium salt surfactant, and the silane coupling agent-modified nanomaterial is 0.4:0.03:0.025:0.2.

[0047] Comparative Example 5

[0048] This comparative example provides a thickening and cutting agent, the preparation method of which differs from that of Example 3 only in that: the amount of tetramethylammonium bromide is 308g, the amount of dioctadecyldimethylammonium chloride is 418g, the amount of perfluorooctyl quaternary ammonium salt is 435g, and the amount of KH-570 modified nano-silica is 470g, yielding the product thickening and cutting agent DRM-5. The molar ratio of the first surfactant, the second surfactant, the fluorinated quaternary ammonium salt surfactant, and the silane coupling agent-modified nanomaterial is 2:0.7:0.6:1.6.

[0049] Test Example 1

[0050] This test example is used to test the thickening and shearing effects of the thickening and shearing agents prepared in Examples 1-8, the thickening and shearing agents prepared in Comparative Examples 1-5, commercially available organo-earth 130D, and commercially available organo-earth 601 in the oil phase.

[0051] The viscosity-enhancing and shearing agents prepared in Examples 1-8, the viscosity-enhancing and shearing agents prepared in Comparative Examples 1-5, commercially available organic clay 130D and commercially available organic clay 601 were added to 300 mL of white oil (the amount added was 2 wt%, based on white oil as 100%). The viscosity and shearing force of the oil phase before aging and after aging (260℃) were tested respectively. Φ600 and Φ3 are the readings of the drilling fluid six-speed viscometer (ZNN-D6B) at 600 revolutions and 3 revolutions respectively when testing rheology.

[0052] The test results are shown in Table 1.

[0053] Table 1

[0054] Table 1 shows that, compared to Comparative Examples 1-5, Organo-Clay 130D, and 601, Examples 1-8 effectively improved the viscosity and shear strength of the oil phase under normal temperature conditions. After aging at 260℃, KRM-3 showed better viscosity-enhancing and shear-strengthening effects than KRM-1, KRM-2, KRM-6, KRM-7, and KRM-8. While KRM-4 and KRM-5 also improved the viscosity and shear strength of the oil phase, the synthesis products consumed more raw materials, required more stringent reaction conditions, and had a greater increase in viscosity, but a smaller increase in shear strength. This could increase the plastic viscosity of the system, leading to excessive pump pressure, which is detrimental to actual drilling. Meanwhile, bis(octadecyl)dimethylammonium chloride showed better effects than dodecyltrimethylammonium bromide, hexadecyltrimethylammonium bromide, and hexadecyltrimethylammonium chloride.

[0055] Test Example 2

[0056] This test case is used to test the effects of the thickening and shearing agents prepared in Examples 1-8 and Comparative Examples 1-5, as well as commercially available organic clays (130D and 601), on the thickening and shearing effects of oil-based drilling fluids.

[0057] The thickening and shearing agents prepared in Examples 1-8 and Comparative Examples 1-5, along with conventional organic soil, were added to oil-based drilling fluids, and the system performance was tested before and after high-temperature aging at 260°C.

[0058] The oil-based drilling fluid used (oil-water ratio 90:10, density 2.5 g / cm³) 3 The basic formula is as follows: 270mL base oil + 30mL CaCl2 aqueous solution (concentration 25wt%) + 12g main emulsifier + 12g co-emulsifier + 15g CaO powder + 5% filtration loss reducer + 1185g barite; wherein the base oil is No. 3 white oil, purchased from Guangdong Maoming Petrochemical Company; the main emulsifier oleamide DR-EM, the co-emulsifier alkanolamide DR-CO, and the filtration loss reducer modified humic acid FLRA were all purchased from China Petroleum Engineering Technology Research Institute Co., Ltd.; the barite was purchased from Lingshou County Woyang Mineral Products Processing Plant.

[0059] The prepared oil-based drilling fluid was poured into an aging tank and aged at 260℃ for 16 hours. After cooling to room temperature, the tank was opened, and the sedimentation stability of the drilling fluid was checked using a glass rod. The results were as follows: hard sedimentation indicated severe barite sedimentation, preventing the freely falling glass rod from reaching the bottom of the aging tank; soft sedimentation indicated a density difference in the drilling fluid within the aging tank, resulting in weaker barite sedimentation, allowing the glass rod to slowly reach the bottom; no sedimentation indicated no density difference between the top and bottom of the drilling fluid after aging. The drilling fluid in the aging tank was then stirred at 12000 rpm for 10 minutes, and then heated to 65℃. The readings at 600 rpm, 300 rpm, 6 rpm, and 3 rpm were measured using a ZNN-D6 six-speed rotational viscometer. The rheological parameters of the drilling fluid were calculated using the following formula: Apparent viscosity: AV = 1 / 2 × 600 r / min (reading) mPa s; Plastic viscosity: PV = 600 r / min (reading) - 300 r / min (reading) mPa s; Dynamic shear force: YP = 1 / 2 × (300 r / min (reading) - PV) Pa; Φ6 and Φ3 are the readings of the drilling fluid six-speed viscometer (ZNN-D6B) at 6 revolutions and 3 revolutions, respectively, when testing the rheology of the drilling fluid. FLHTHP is the reading for high-temperature and high-pressure filtration loss measured using a drilling fluid high-temperature and high-pressure filtration loss meter (GGS71).

[0060] The test results are shown in Tables 2 and 3. Table 2 shows the performance comparison of oil-based drilling fluid before and after high-temperature aging, and Table 3 shows the performance comparison of oil-based drilling fluid before and after aging at 260℃ with the addition of (addition amount of 2wt%, based on 100% of oil-based drilling fluid) of viscosity enhancers and cutting agents of Examples 1-8 and Comparative Examples 1-5 and organic soil.

[0061] Table 2

[0062] As shown in Table 2, the basic formulation without the addition of thickener and shear enhancer has low viscosity and shear before aging. After aging at 260℃, hard sedimentation occurs, and the dynamic shear force after aging is almost zero. This indicates that the basic formulation has poor high-temperature rheological stability, low system shear force, and insufficient structural force, making it difficult to effectively suspend the weighted material.

[0063] Table 3

[0064] Table 3 shows that the apparent viscosity and dynamic shear strength of the examples and comparative examples before aging are significantly improved compared to the base formulation. However, after aging at 260℃, the viscosity and shear strength of the overall system show a decreasing trend, with comparative examples 1-4 and conventional organic clay and nano-blocking agents showing poor effects. In examples 1-5, KRM-3 shows better viscosity-enhancing and shear-strengthening effects. Furthermore, analysis of the high-temperature and high-pressure filtration loss data shows that the blocking thickeners formed in comparative examples 1-4 have a weaker filtration loss reduction effect because the nanomaterials and polymers do not form graft polymerization. In contrast, the blocking thickeners in examples 1-8 effectively reduce high-temperature and high-pressure filtration loss, with KRM-3 showing the best filtration loss reduction effect.

[0065] As can be seen from the comparison of the examples and comparative examples, when the raw materials are not modified with different carbon chain surfactants, do not introduce fluorinated surfactants, do not react with nanomaterials modified with silane coupling agents, or are simply mixed with raw materials, the thickening and shearing agents have little effect on the rheological properties of the basic drilling fluid after high temperature, making it difficult to effectively stabilize the viscosity and shearing, and the drilling fluid is prone to sedimentation.

[0066] The viscosity-enhancing and shear-lifting agent provided by this invention, using specific raw materials and reaction processes, stabilizes the performance of the basic formulation, which deteriorates after high temperature, and exhibits excellent high-temperature resistance. Analysis results show that the viscosity-enhancing and shear-lifting agent synthesized in the examples can effectively improve the viscosity and shear of the basic drilling fluid formulation, restoring it to meet the requirements of field construction. The viscosity-enhancing and shear-lifting agents synthesized in Comparative Examples 1-4 cannot effectively stabilize the viscosity and shear of the system after high-temperature aging, which is detrimental to field construction of the drilling fluid. Although Comparative Example 5 can stabilize viscosity and shear, it consumes a large amount of raw materials for the treatment agent synthesis, and the synthesis process is relatively more complex, which is not conducive to field application.

[0067] Furthermore, if the proportion of the reacting compounds is not within the preferred range, a small amount will result in poor viscosity-enhancing and shearing effects, making it difficult to stabilize viscosity and shearing. A large amount will increase the viscosity and shearing of the drilling fluid, affecting the rheology of the drilling fluid, and may even affect the pump pressure during field application.

[0068] In summary, the viscosity-enhancing and shear-lifting agent provided by this invention enables drilling fluids to maintain good high-temperature rheological stability after high-temperature hot rolling. When applied to oil-based drilling fluid systems, this agent effectively improves the viscosity and shear strength of the system and provides good stability against high-temperature aging, with a temperature resistance exceeding 260℃.

Claims

1. A method for preparing a viscosity enhancer and cutting agent for oil-based drilling fluids, wherein, Includes the following steps: The first surfactant, montmorillonite, and retinoic acid are mixed and subjected to a first reaction to obtain a first reaction intermediate. The first reaction intermediate and the second surfactant are mixed to carry out a second reaction to obtain the second reaction intermediate; The second reaction intermediate and a fluorinated quaternary ammonium salt surfactant are mixed and subjected to a third reaction to obtain the third reaction intermediate; The third reaction intermediate is mixed with silane coupling agent modified nanomaterials under alkaline conditions to carry out a fourth reaction, thereby obtaining the viscosity enhancer and shearing agent for oil-based drilling fluid. The first surfactant is selected from one or more of tetramethylammonium bromide, tetrabutylammonium bromide, and trimethylbenzylammonium bromide; the second surfactant is selected from one or more of dodecyltrimethylammonium bromide, hexadecyltrimethylammonium bromide, hexadecyltrimethylammonium chloride, and bis(octadecyltrimethylammonium chloride).

2. The method for preparing the viscosity enhancer and cutting agent for oil-based drilling fluid according to claim 1, wherein, The fluorinated quaternary ammonium salt surfactant is selected from one or more combinations of perfluorooctyl sulfonic acid ethyl quaternary ammonium salt, perfluorooctyl quaternary ammonium iodide, and perfluorooctyl carboxylic acid quaternary ammonium salt iodide.

3. The method for preparing the viscosity enhancer and cutting agent for oil-based drilling fluid according to claim 1 or 2, wherein, The silane coupling agent modified nanomaterial is selected from one or more combinations of KH-570 modified nano-silica, KH-570 modified nano-titanium dioxide, KH550 modified nano-silica, and KH550 modified nano-titanium dioxide.

4. The method for preparing the viscosity enhancer and cutting agent for oil-based drilling fluid according to claim 1, wherein, The weight ratio of the montmorillonite to the montmorillonite is 60~80:40~20.

5. The method for preparing the viscosity enhancer and cutting agent for oil-based drilling fluid according to any one of claims 1 to 3, wherein, The molar ratio of the first surfactant, the second surfactant, the fluorinated quaternary ammonium salt surfactant, and the silane coupling agent modified nanomaterial is 0.5~1.5:0.1~1.0:0.05~0.5:0.1~1.

5.

6. The method for preparing the viscosity enhancer and cutting agent for oil-based drilling fluid according to claim 1, wherein, The temperature of the first reaction is 40~70℃, and the time is 3~5h.

7. The method for preparing the viscosity enhancer and cutting agent for oil-based drilling fluid according to claim 1, wherein, The temperature of the second reaction is 50~80℃, and the time is 4~8h.

8. The method for preparing the viscosity enhancer and cutting agent for oil-based drilling fluid according to claim 1 or 2, wherein, The temperature of the third reaction is 70~90℃, and the time is 10~14h.

9. The method for preparing the viscosity enhancer and cutting agent for oil-based drilling fluid according to any one of claims 1 to 3, wherein, The fourth reaction is carried out at a temperature of 80-100℃ for 6-10 hours.

10. A viscosity improver and cuttings-enhancing agent for oil-based drilling fluids, wherein, It is prepared by the preparation method according to any one of claims 1 to 9.

11. An oil-based drilling fluid, wherein, Includes the thickening and cutting agent as described in claim 10.

12. The oil-based drilling fluid according to claim 11, wherein, The amount of the thickening and shearing agent used is 0.5 to 2.5% of the weight of the oil-based drilling fluid.

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