A temperature-resistant rheological modifier for antarctic drilling fluid and a preparation method and application thereof

Abstract

The application provides a temperature-resistant-65 DEG C rheological modifier for Antarctic drilling fluid and a preparation method and application thereof, and belongs to the technical field of polar drilling. The preparation method of the temperature-resistant-65 DEG C rheological modifier for Antarctic drilling fluid comprises the following steps: (1) dispersing atta gel in deionized water, stirring and hydrating to obtain a suspension; (2) adding an organic silicon quaternary ammonium salt aqueous solution and a polydimethyl diallyl ammonium chloride aqueous solution into the suspension obtained in the step (1) to perform a reaction, and obtaining a mixed solution; (3) adding a 3-chloropropyl trimethoxysilane aqueous solution into the mixed solution obtained in the step (2) to perform a reaction; after the reaction is completed, centrifugation, drying and crushing are performed to obtain the temperature-resistant-65 DEG C rheological modifier for Antarctic drilling fluid. The rheological modifier can significantly improve the dynamic shear force and gel strength of the drilling fluid and improve the suspension capacity of the drilling fluid.

Description

Technical Field

[0001] This invention relates to a rheology modifier for Antarctic drilling fluid with a temperature resistance of -65℃, its preparation method and application, belonging to the field of polar drilling technology. Background Technology

[0002] Antarctica contains abundant oil and gas resources, as well as important paleontological and climatic information. Antarctic drilling technology is a key means of obtaining this information. However, the low surface temperature and complex subglacial geological environment of Antarctica pose significant challenges to drilling fluid technology. Currently, commonly used Antarctic drilling fluids include petroleum-based and ester-based fluids. However, these fluids have poor low-temperature rheological adjustment properties, which cannot meet the exploration requirements of subglacial rock formations, seriously hindering the development of Antarctic scientific research.

[0003] Currently, there are numerous reports on the development of conventional drilling fluid rheology modifiers. For example, Chinese patent document CN119638587A discloses a copolymer rheology modifier obtained by polymerization of enamide monomers, sulfonic acid monomers, alkyl methacrylates, and zwitterionic crosslinking agents. This modifier can maintain a viscosity retention rate of up to 86.56% after aging at 240℃ for 16 hours, exhibiting excellent rheological properties. Chinese patent document CN121930483A discloses a temperature-responsive hyperbranched rheology modifier prepared from hyperbranched polyester, long-chain alkane acyl halide materials with ≥8 carbon atoms, temperature-responsive polymers, and polyisobutylene materials. This modifier can maintain low viscosity under low temperature (≤120℃) and high shear, effectively reducing equivalent circulation density and pressure loss, while maintaining high viscosity under high temperature (>220℃) and high shear, effectively suspending weighting agents and drill cuttings. Chinese patent document CN108559464A discloses an oil-based drilling fluid flow modifier, which is composed of a composite modified organic clay and a modified thermoplastic elastic resin.

[0004] Currently, there is limited research on cryogenic drilling fluid rheology modifiers for Antarctic drilling. Therefore, there is an urgent need to develop cryogenic drilling fluid rheology modifiers suitable for the Antarctic region to improve the suspension and carrying efficiency of drilling fluids for cuttings during polar drilling, thereby increasing drilling efficiency. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a rheology modifier for Antarctic drilling fluids with a temperature resistance of -65℃, its preparation method, and its application. The rheology modifier of this invention can significantly improve the dynamic shear strength and gel strength of drilling fluids, and enhance their suspension capacity.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows: A method for preparing a rheology modifier for Antarctic drilling fluid with a temperature resistance of -65℃ includes the following steps: (1) Disperse the attagel in deionized water and stir to hydrate it to obtain a suspension; (2) Add an aqueous solution of organosilicon quaternary ammonium salt and an aqueous solution of polydimethyldiallyl ammonium chloride to the suspension obtained in step (1) and react to obtain a mixture; (3) Add 3-chloropropyltrimethoxysilane aqueous solution to the mixture obtained in step (2) and react; after the reaction is completed, centrifuge, dry and crush to obtain a rheology modifier for Antarctic drilling fluid with a temperature resistance of -65℃.

[0007] According to a preferred embodiment of the present invention, the concentration of ata gel in the suspension in step (1) is 8wt%-12wt%.

[0008] According to a preferred embodiment of the present invention, the stirring and hydration time in step (1) is 20-30 hours, and the stirring and hydration temperature is room temperature.

[0009] According to a preferred embodiment of the present invention, the organosilicon quaternary ammonium salt in step (2) is dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride (CAS No.: 27668-52-6) or dimethyloctadecyl[3-(triethoxysilyl)propyl]ammonium chloride (CAS No.: 62117-57-1); the concentration of the organosilicon quaternary ammonium salt aqueous solution is 2wt%-3wt%; and the mass ratio of the attagel in the suspension to the organosilicon quaternary ammonium salt in the organosilicon quaternary ammonium salt aqueous solution is 7:1-2.

[0010] According to a preferred embodiment of the present invention, the polydimethyldiallyl ammonium chloride in step (2) has a weight-average molecular weight of 100,000-350,000; the concentration of the aqueous solution of polydimethyldiallyl ammonium chloride is 1.5wt%-2wt%; the mass ratio of the organosilicon quaternary ammonium salt to polydimethyldiallyl ammonium chloride is 2-3:1; and the polydimethyldiallyl ammonium chloride has the structure shown in Formula I: ; I.

[0011] According to a preferred embodiment of the present invention, the temperature of the reaction in step (2) is 75-85°C; and the reaction time is 3-5 hours.

[0012] According to a preferred embodiment of the present invention, the concentration of the 3-chloropropyltrimethoxysilane aqueous solution in step (3) is 1.5wt%-2.5wt%; the mass ratio of 3-chloropropyltrimethoxysilane in the 3-chloropropyltrimethoxysilane aqueous solution to the organosilicon quaternary ammonium salt in the organosilicon quaternary ammonium salt aqueous solution is 1:2-3.

[0013] According to a preferred embodiment of the present invention, the reaction temperature in step (3) is 85-95°C; and the reaction time is 2-3 hours.

[0014] According to a preferred embodiment of the present invention, the drying in step (3) is performed at 60-70°C to constant weight.

[0015] This invention provides a rheology modifier for Antarctic drilling fluid that is resistant to temperatures up to -65°C, prepared using the method described above.

[0016] According to the present invention, the above-mentioned rheology modifier for Antarctic drilling fluid with a temperature resistance of -65°C is used in drilling fluids for polar formations; preferably, the polar region is Antarctica.

[0017] In this invention, room temperature has a commonly known meaning, referring to 25±5℃.

[0018] The technical features and beneficial effects of this invention are as follows:

[0019] 1. The preparation method of this invention is simple, and the resulting rheology modifier is safe, environmentally friendly, and has no irritating odor.

[0020] 2. The rheology modifier of this invention is prepared from four monomers: attapulgite (attapulgite clay), organosilicon quaternary ammonium salt, polydimethyldiallyl ammonium chloride, and 3-chloropropyltrimethoxysilane. First, the organosilicon quaternary ammonium salt is adsorbed onto the surface of attapulgite particles via ion exchange. Its long carbon chain imparts stronger oleophilicity to the attapulgite surface, enhancing the dispersion stability of the product in drilling fluid. Simultaneously, the silane groups in the molecule undergo hydrolytic condensation with the silanol groups on the attapulgite surface, forming covalent bonds. Meanwhile, polydimethyldiallyl ammonium chloride carries a large number of cyclic quaternary ammonium cations, which can be adsorbed simultaneously onto the surface of multiple attapulgite rods, acting as an ion bridge to connect the discrete rods. Secondly, based on the above reactions, 3-chloropropyltrimethoxysilane interacts with the silanol groups on the attapulgite surface, further stabilizing the molecular structure of the rheology modifier.

[0021] 3. The rheology modifier in this invention can effectively improve the dynamic shear force and gel strength of drilling fluid under ultra-low temperature conditions, thus enhancing its suspension performance. Furthermore, the resulting network structure significantly improves the colloidal stability of the drilling fluid at ultra-low temperatures.

[0022] 4. The monomers used in the preparation of the rheology modifier of this invention, through an optimal combination of specific types and proportions, work together to achieve the excellent effects of this invention. The ratio of ata gel to organosilicon quaternary ammonium salt in this invention must be appropriate. If the ratio is too high, the lipophilicity of the ata gel cannot be significantly improved, resulting in poor dispersibility of the rheology modifier in drilling fluid and severely affecting its ultra-low temperature rheological properties. Conversely, if the ratio is too low, excess organosilicon quaternary ammonium salt will disrupt its physical adsorption on the surface of the ata gel, thereby affecting the molecular structural stability of the rheology modifier. Attached Figure Description

[0023] Figure 1Infrared spectrum of the -65℃ temperature resistant rheology modifier for Antarctic drilling fluid prepared in Example 1. Detailed Implementation

[0024] The present invention will be further described below through specific embodiments, but is not limited thereto.

[0025] Unless otherwise specified, the experimental methods described in the examples are conventional methods; the reagents and materials used are commercially available unless otherwise specified.

[0026] The polydimethyl diallyl ammonium chloride used in the examples has a weight-average molecular weight of 200,000-350,000; the 1.8 wt% polydimethyl diallyl ammonium chloride aqueous solution was obtained by diluting a commercially available 20 wt% polydimethyl diallyl ammonium chloride aqueous solution with water.

[0027] Example 1 A method for preparing a rheology modifier for Antarctic drilling fluid with a temperature resistance of -65℃ includes the following steps: (1) Disperse the atta gel in deionized water and stir at room temperature for 24 h to fully hydrate it, so as to obtain a suspension with a concentration of 10 wt%; (2) Pour the suspension obtained in step (1) into a three-necked flask and heat it to 80°C while stirring. Then add a 2.5 wt% aqueous solution of dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride and a 1.8 wt% aqueous solution of polydimethyldiallylammonium chloride to the suspension and react at 80°C for 4 h to obtain a mixture. The mass ratio of Ata gel to dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride is 7:1.5; the mass ratio of dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride to polydimethyldiallylammonium chloride is 2.5:1. (3) Add a 2.0 wt% aqueous solution of 3-chloropropyltrimethoxysilane to the mixture obtained in step (2) and react at 90°C for 2.5 h. The mass ratio of 3-chloropropyltrimethoxysilane to dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride is 1:2.5. After the reaction is completed, centrifuge the resulting reaction solution and dry the precipitate obtained by centrifugation at 65°C to constant weight. Then crush and pass through a 200-mesh sieve to obtain a rheology modifier for Antarctic drilling fluid with a temperature resistance of -65°C.

[0028] The infrared spectrum of the -65℃ temperature-resistant rheology modifier for Antarctic drilling fluid obtained in this embodiment is shown below. Figure 1 As shown, by Figure 1 It can be seen that 3620cm -1 The peak near the 3360 cm⁻¹ is the stretching vibration peak of the structural hydroxyl groups inside the Ata gel; -1The nearby peak is the stretching vibration peak of OH in adsorbed water, and its intensity is relatively weak; 2925 cm⁻¹ -1 and 2850cm -1 The peaks at 1630 cm⁻¹ represent the CH stretching vibration peaks of methyl and methylene groups, respectively; -1 The peak at 1465 cm⁻¹ represents the stretching vibration peak of olefins. -1 The peak nearby is a bending vibration peak of -CH2-; 1030 cm⁻¹ -1 The nearby peak represents the stretching vibration of Si-O; 790 cm⁻¹ -1 The nearby peaks represent the stretching vibration of Si-C and the rocking vibration of CH in the methoxy group (-OCH3). The appearance of these infrared characteristic peaks indicates that the target product was successfully prepared.

[0029] Example 2 A method for preparing a rheology modifier for Antarctic drilling fluid with a temperature resistance of -65℃ is described in Example 1, except that the concentration of the suspension in step (1) is replaced by 12wt% instead of 10wt%.

[0030] Example 3 A method for preparing a rheology modifier for Antarctic drilling fluid with a temperature resistance of -65℃ is described in Example 1, except that in step (2), dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride is replaced with dimethyloctadecyl[3-(triethoxysilyl)propyl]ammonium chloride.

[0031] Example 4 A method for preparing a rheology modifier for Antarctic drilling fluid with a temperature resistance of -65℃ is described in Example 1, except that: in step (2), the mass ratio of Ata gel to dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride is 7:1.

[0032] Example 5 A method for preparing a rheology modifier for Antarctic drilling fluid with a temperature resistance of -65℃ is described in Example 1, except that: in step (2), the mass ratio of Ata gel to dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride is 7:2.

[0033] Example 6 A method for preparing a rheology modifier for Antarctic drilling fluid with a temperature resistance of -65℃ is described in Example 1, except that: in step (2), the mass ratio of dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride to polydimethyldiallylammonium chloride is 2:1.

[0034] Example 7 A method for preparing a rheology modifier for Antarctic drilling fluid with a temperature resistance of -65℃ is described in Example 1, except that: in step (2), the mass ratio of dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride to polydimethyldiallylammonium chloride is 3:1.

[0035] Example 8 A method for preparing a rheology modifier for Antarctic drilling fluid with a temperature resistance of -65℃ is described in Example 1, except that in step (3), the mass ratio of 3-chloropropyltrimethoxysilane to dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride is replaced by 1:3 instead of 1:2.5.

[0036] Example 9 A method for preparing a rheology modifier for Antarctic drilling fluid with a temperature resistance of -65℃ is described in Example 1, except that in step (3), the mass ratio of 3-chloropropyltrimethoxysilane to dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride is replaced by 1:2.5 instead of 1:2.

[0037] Comparative Example 1 A method for preparing a rheology modifier for Antarctic drilling fluid is described in Example 1, except that in step (1), ata gel is replaced with montmorillonite, and other conditions are the same as in Example 1.

[0038] Comparative Example 2 A method for preparing a rheology modifier for Antarctic drilling fluid is described in Example 1, except that in step (2), dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride is replaced with dimethylbis(octadecyl)ammonium chloride.

[0039] Comparative Example 3 A method for preparing a rheology modifier for Antarctic drilling fluid is described in Example 1, except that in step (3), 3-chloropropyltrimethoxysilane is replaced with vinyltriethoxysilane.

[0040] Comparative Example 4 A method for preparing a rheology modifier for Antarctic drilling fluid is described in Example 1, except that the reaction temperature in step (2) is replaced by 60°C instead of 80°C, while the other conditions are the same as in Example 1.

[0041] Comparative Example 5 A method for preparing a rheology modifier for Antarctic drilling fluid is described in Example 1, except that the reaction time in step (2) is replaced by 2 hours instead of 4 hours, while the other conditions are the same as in Example 1.

[0042] Experimental Example 1

[0043] Colloidal content and rheological properties were tested on the rheology modifiers prepared in the examples and comparative examples.

[0044] (1) Sample preparation: The drilling fluid base composition is as follows: isododecane was selected as the Antarctic drilling fluid base oil, and 3% of the base oil mass of Hanko emulsifier DNS-86 was added. The base fluid was prepared by stirring thoroughly on a high-speed mixer for 20 minutes at a stirring speed of 500 r / min. Then, the rheology modifiers from the examples or comparative examples were added, with an addition amount of 2% of the base oil mass. The mixture was stirred on a high-speed mixer for another 20 minutes at a stirring speed of 500 r / min to obtain the sample. Its performance at -65℃ was tested.

[0045] (2) Test method: Colloidal content test: Pour the prepared drilling fluid sample into a colorimetric tube, then place the colorimetric tube in a low-temperature constant temperature chamber (-65℃) and let it stand for 16 hours. Calculate the colloidal content: Colloidal content = (lower volume / total volume) × 100%, where the total volume is the sum of the upper volume and the lower volume. The lower volume refers to the volume of the colloid, and the upper volume is the volume of the clear liquid after sedimentation. Rheological property testing: The prepared drilling fluid sample was loaded into the test module, and the readings at 600 r and 300 r were measured by a ZNN-D6 low-temperature six-speed rheometer. The apparent viscosity (AV), plastic viscosity (PV), and dynamic shear force (YP) were then calculated. Gel strength test: The drilling fluid was stirred for 10 seconds at 600 rpm using a six-speed viscometer. After stirring, the switch was turned off, and the drilling fluid was allowed to stand for 10 seconds. After standing, the speed was set to 3 rpm, and the maximum value was read. The gel strength (Gel 10s) is 0.5 times the scale value. The gel strength (Gel 10min) test method is the same as that for Gel 10s, the only difference being that the maximum value of the instrument at 3 rpm is measured after the drilling fluid has stood for 10 minutes.

[0046] The results of the tests on colloidal content, rheology, and gel strength are shown in Table 1.

[0047] Table 1. Performance test results of rheology modifiers at -65℃

[0048] As shown in Table 1, the drilling fluid rheology modifier prepared by this invention exhibits excellent performance; it demonstrates good low-temperature colloidal stability at -65℃, with a colloidal content exceeding 83.2% after 16 hours of standing; simultaneously, it also exhibits good shearing effect, with a shearing rate exceeding 200% at -65℃. These experimental results indicate that this wetting agent enhances the colloidal stability and rheological properties of the drilling fluid under low-temperature conditions.

[0049] In summary, the novel rheology modifier for drilling fluids with a temperature resistance of -65℃ of the present invention can meet the needs of polar drilling.

[0050] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, and these simple modifications all fall within the protection scope of the present invention. Furthermore, it should be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately. In addition, various different embodiments of the present invention can also be arbitrarily combined, as long as they do not violate the spirit of the present invention, they should also be considered as the content disclosed by the present invention.

Claims

1. A method for preparing a rheology modifier resistant to -65℃ for Antarctic drilling fluid, characterized in that, The steps include the following: (1) Disperse the atagel in deionized water and stir to hydrate it to obtain a suspension; the concentration of the atagel in the suspension is 8wt%-12wt%; (2) Add an aqueous solution of organosilicon quaternary ammonium salt and an aqueous solution of polydimethyldiallyl ammonium chloride to the suspension obtained in step (1) and react to obtain a mixture; the organosilicon quaternary ammonium salt is dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride or dimethyloctadecyl[3-(triethoxysilyl)propyl]ammonium chloride, the mass ratio of the attagel in the suspension to the organosilicon quaternary ammonium salt in the aqueous solution is 7:1-2; the mass ratio of the organosilicon quaternary ammonium salt to polydimethyldiallyl ammonium chloride is 2-3:1; the reaction temperature is 75-85℃; the reaction time is 3-5h; (3) Add 3-chloropropyltrimethoxysilane aqueous solution to the mixture obtained in step (2) and react; after the reaction is completed, centrifuge, dry and pulverize to obtain a rheology modifier for Antarctic drilling fluid with a temperature resistance of -65℃; the mass ratio of 3-chloropropyltrimethoxysilane in the aqueous solution of 3-chloropropyltrimethoxysilane to the organosilicon quaternary ammonium salt in the aqueous solution of organosilicon quaternary ammonium salt is 1:2-3; the reaction temperature is 85-95℃; the reaction time is 2-3h.

2. The method for preparing the -65℃ temperature-resistant rheology modifier for Antarctic drilling fluid according to claim 1, characterized in that, The stirring and hydration time in step (1) is 20-30 hours, and the stirring and hydration temperature is room temperature.

3. The method for preparing the -65℃ temperature-resistant rheology modifier for Antarctic drilling fluid according to claim 1, characterized in that, The concentration of the organosilicon quaternary ammonium salt aqueous solution in step (2) is 2wt%-3wt%.

4. The method for preparing the -65℃ temperature-resistant rheology modifier for Antarctic drilling fluid according to claim 1, characterized in that, The weight-average molecular weight of the polydimethyldiallyl ammonium chloride in step (2) is 100,000-350,000; the concentration of the aqueous solution of the polydimethyldiallyl ammonium chloride is 1.5wt%-2wt%.

5. The method for preparing the -65℃ temperature-resistant rheology modifier for Antarctic drilling fluid according to claim 1, characterized in that, The concentration of the 3-chloropropyltrimethoxysilane aqueous solution in step (3) is 1.5wt%-2.5wt%.

6. The method for preparing the -65℃ temperature-resistant rheology modifier for Antarctic drilling fluid according to claim 1, characterized in that, The drying process described in step (3) involves drying at 60-70°C to a constant weight.

7. A rheology modifier for Antarctic drilling fluid with a temperature resistance of -65℃, characterized in that, It is prepared by the preparation method described in any one of claims 1-6.

8. The application of the -65℃ temperature-resistant rheology modifier for Antarctic drilling fluid as described in claim 7 in polar formation drilling fluids, characterized in that, The polar region mentioned is Antarctica.

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