Organic soil for high-temperature-resistant drilling fluid and preparation method of organic soil

Abstract

The invention discloses organic soil for high-temperature-resistant drilling fluid, which is prepared from the following components in parts by weight: 50 to 80 parts of Na-montmorillonite, 10 to 30 parts of attapulgite, 10 to 30 parts of long-chain quaternary ammonium salt and 5 to 15 parts of chelating agent. Montmorillonite and attapulgite are compounded to serve as a modified raw material, so that the situation that the high-temperature resistance of organic soil is affected due to the fact that a single layered structure of montmorillonite has a fault in a high-temperature state is avoided, long-chain quaternary ammonium salt is adopted as a primary intercalator to effectively enter the interlayer of montmorillonite, the interlayer spacing is increased, and the high-temperature resistance of the organic soil is improved. Then, a chelating agent is adopted as a secondary intercalator to connect two adjacent layers of montmorillonite through chemical bonds, meanwhile, a primary intercalator modifier and montmorillonite are further connected to solve the problem that ionic bonds are prone to desorption, then the organic soil for the high-temperature-resistant drilling fluid is obtained, the high-temperature-resistant performance of the organic soil can reach 200 DEG C or above, and the high-temperature-resistant performance of the organic soil can reach 200 DEG C or above; and meanwhile, the organic soil has relatively high colloid rate and relatively good tackifying and cutting-improving effects at the temperature.

Description

Technical Field

[0001] The invention belongs to the technical field of drilling fluid, and in particular relates to an organic soil for high temperature resistant drilling fluid and a preparation method thereof. Background Art

[0002] Drilling fluid is a general term for various circulating fluids that meet the needs of drilling work with its multiple functions during the drilling process. Different drilling depths have different requirements for drilling fluid performance. This is because as the well depth increases, the bottom of the well is under high temperature and high pressure conditions, the drilling section is long and there are large sections of open holes, and many complex formations must be drilled through. Therefore, its operating conditions are much more stringent than those of general wells, so higher requirements are also placed on the performance of drilling fluids (especially high temperature resistance). Organic clay is the most widely used rheology control agent in oil-based drilling fluids. Due to its good lipophilicity and large interlayer spacing, organic clay controls the rheological behavior of oil-based drilling fluids by dispersing and swelling in the base oil. At present, the organic clay used in actual drilling operations is an oleophilic colloidal material obtained by organic modification of montmorillonite. The basic structural unit of montmorillonite is a 2:1 layered structure consisting of two layers of silicon-oxygen tetrahedral sheets sandwiched between a layer of aluminum-oxygen octahedral sheets, which is a typical layered cinnamate clay mineral. Due to isomorphous substitution in the structure of montmorillonite, its crystal layers carry a certain amount of structural negative charge. In order to maintain electrical neutrality, the montmorillonite layers can adsorb an equal amount of cations. Conventional organic soil is generally made of montmorillonite modified by a single intercalation adsorption of long-chain quaternary ammonium salts. When this type of organic soil is evaluated below 150°C, the colloid rate is high and the shear and viscosity increase effect is good, but after exceeding 180°C, the performance deteriorates significantly. The quaternary ammonium salt and the montmorillonite layers are mainly connected through charge interaction. Under high temperature conditions, the adsorbed long-chain quaternary ammonium salt modifier is easy to disperse and desorb, resulting in the failure of the organic soil, which seriously affects the overall performance of the drilling fluid. It can be seen that effectively improving the high temperature resistance of organic soil plays a vital role in improving the high temperature resistance of drilling fluid. Summary of the invention

[0003] The present invention aims to solve the technical problem that the high temperature resistance of organic soil for high temperature resistant drilling fluid in the prior art is poor; an organic soil for high temperature resistant drilling fluid and a preparation method thereof are proposed to achieve the high temperature resistance of the organic soil reaching above 200°C, while having a higher colloid rate and better viscosity increasing and shearing effect at this temperature.

[0004] In order to achieve the above purpose, the following technical solutions are adopted:

[0005] On one hand, the present invention provides an organic soil for high temperature resistant drilling fluid, which comprises the following components by weight: 50-80 parts of sodium montmorillonite, 10-30 parts of attapulgite, 10-30 parts of long chain quaternary ammonium salt and 5-15 parts of chelating agent.

[0006] Furthermore, the long-chain quaternary ammonium salt is one of n-alkyltrimethylammonium chloride or n-alkyltrimethylammonium bromide, wherein n=12-18.

[0007] Furthermore, the chelating agent is one of n-alkyltrimethylphosphonium chloride or n-alkyltrimethylphosphonium bromide, wherein n=(12, 14 or 16).

[0008] Another aspect of the present invention provides a method for preparing organic soil for high temperature resistant drilling fluid, comprising the following steps:

[0009] (1) Weighing sodium montmorillonite, attapulgite, long-chain quaternary ammonium salt and chelating agent according to weight parts;

[0010] (2) Mix the weighed sodium montmorillonite and attapulgite with water, stir for 8-15 min at 75-85° C., add the weighed long-chain quaternary ammonium salt, stir and adjust the pH to 7-8, and continue stirring for 0.5-2 h to obtain a primary intercalation mixture;

[0011] (3) adding ethanol and the weighed chelating agent to the primary intercalation mixture, and continuing to stir at 75-85° C. for 2 h to obtain a secondary intercalation mixture;

[0012] (4) The secondary intercalation mixed liquid is cooled, filtered, washed, dried, crushed, and sieved to obtain organic soil for high temperature resistant drilling fluid.

[0013] Furthermore, in the step (2), the mixing ratio of sodium montmorillonite, attapulgite and water is (50-80) parts: (10-30) parts: (1000-1500) parts by weight.

[0014] Furthermore, in step (2), the solution for adjusting the pH is a hydrochloric acid solution.

[0015] Furthermore, in the step (3), the ratio of the added amount of ethanol and the added amount of the chelating agent is (50-100) parts: (5-15) parts by weight.

[0016] Furthermore, in step (4), the washing process is: repeatedly washing with deionized water until no white precipitate is found in the supernatant liquid detected by silver nitrate.

[0017] Furthermore, in step (4), the drying temperature is 80-100° C. and the drying time is 8-12 h.

[0018] Furthermore, in step (4), a 200-mesh sieve is used for sieving.

[0019] The beneficial effects of the present invention are:

[0020] The present invention adopts montmorillonite and attapulgite as modified raw materials to prevent the single layered structure of montmorillonite from being broken under high temperature and thus affecting the high temperature resistance of organic soil. A long-chain quaternary ammonium salt is used as a primary intercalation agent to effectively enter the montmorillonite interlayer and increase the interlayer spacing. A chelating agent is then used as a secondary intercalation agent to connect two adjacent montmorillonite layers by chemical bonds. The primary intercalation agent modifier is further connected to the montmorillonite to improve the problem of easy desorption of ionic bonds, thereby obtaining organic soil for high temperature resistant drilling fluid. The high temperature resistance of the organic soil reaches above 200°C, and the organic soil has a higher colloid rate and better viscosity-increasing and shear-improving effects at this temperature. DETAILED DESCRIPTION

[0021] The present application will be described clearly and completely below in conjunction with the technical solutions of the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0022] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicating the orientation or positional relationship are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the said features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0023] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0024] In the present application, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0025] The disclosure below provides many different embodiments or examples to realize the different structures of the present application. In order to simplify the disclosure of the present application, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present application. In addition, the present application can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the various specific processes and material examples provided by the present application, but those of ordinary skill in the art can appreciate the application of other processes and / or the use of other materials.

[0026] Example 1

[0027] Weigh 40g of sodium montmorillonite and 10g of attapulgite, add them into 1000mL of deionized water and mix them evenly. After stirring at 80°C for 10min, add 15g of dodecyltrimethylammonium chloride, stir and adjust the pH to 7 with 0.01mol / L hydrochloric acid, continue stirring for 1.5h to obtain a primary intercalation mixture.

[0028] 5 g of hexadecyltrimethoxyphosphine chloride and 50 mL of ethanol were added to the primary intercalation mixture, and the mixture was stirred at 80° C. for 2 h to obtain a secondary intercalation mixture.

[0029] The secondary intercalation mixture was cooled to room temperature, washed repeatedly with deionized water, filtered, and the upper clear layer was detected with silver nitrate until no white precipitate was produced. It was dried at 100°C for 10 hours, and then crushed through a 200-mesh sieve to obtain organic soil 1#.

[0030] Example 2

[0031] Weigh 40g of sodium montmorillonite and 10g of attapulgite, add them into 1000mL of deionized water and mix them evenly. After stirring at 80°C for 10min, add 15g of tetradecyltrimethylammonium bromide, stir and adjust the pH to 7 with 0.01mol / L hydrochloric acid, continue stirring for 1.5h to obtain a primary intercalation mixture.

[0032] 5 g of hexadecyltrimethoxyphosphine chloride and 50 mL of ethanol were added to the primary intercalation mixture, and the mixture was stirred at 80° C. for 2 h to obtain a secondary intercalation mixture.

[0033] The secondary intercalation mixture was cooled to room temperature, washed repeatedly with deionized water, filtered, and the upper clear layer was detected with silver nitrate until no white precipitate was produced. It was dried at 100°C for 10 hours, and then crushed through a 200-mesh sieve to obtain organic soil 2#.

[0034] Example 3

[0035] Weigh 40g of sodium montmorillonite and 10g of attapulgite, add them into 1000mL of deionized water and mix them evenly. After stirring at 80°C for 10min, add 15g of hexadecyltrimethylammonium chloride, stir and adjust the pH to 7 with 0.01mol / L hydrochloric acid, continue stirring for 1.5h to obtain a primary intercalation mixture.

[0036] 5 g of hexadecyltrimethoxyphosphine chloride and 50 mL of ethanol were added to the primary intercalation mixture, and the mixture was stirred at 80° C. for 2 h to obtain a secondary intercalation mixture.

[0037] The secondary intercalation mixture was cooled to room temperature, washed repeatedly with deionized water, filtered, and the upper clear layer was detected with silver nitrate until no white precipitate was produced. It was dried at 100°C for 10 hours, and then crushed through a 200-mesh sieve to obtain organic soil 3#.

[0038] Example 4

[0039] Weigh 35 g of sodium montmorillonite and 15 g of attapulgite, add them into 1000 mL of deionized water and mix them evenly. After stirring at 80 °C for 10 min, add 10 g of hexadecyltrimethylammonium chloride, stir and adjust the pH to 7 with 0.01 mol / L hydrochloric acid, continue stirring for 1.5 h, and obtain a primary intercalation mixture.

[0040] 10 g of hexadecyltrimethoxyphosphine chloride and 50 mL of ethanol were added to the primary intercalation mixture, and the mixture was stirred at 80° C. for 2 h to obtain a secondary intercalation mixture.

[0041] The secondary intercalation mixture was cooled to room temperature, washed repeatedly with deionized water, filtered, and the upper clear layer was detected with silver nitrate until no white precipitate was produced. It was dried at 100°C for 10 hours, and then crushed through a 200-mesh sieve to obtain organic soil 4#.

[0042] Example 5

[0043] Weigh 40g of sodium montmorillonite and 10g of attapulgite, add them into 1000mL of deionized water and mix them evenly. After stirring at 80°C for 10min, add 15g of hexadecyltrimethylammonium chloride, stir and adjust the pH to 7 with 0.01mol / L hydrochloric acid, continue stirring for 1.5h to obtain a primary intercalation mixture.

[0044] 5 g of hexadecyltrimethoxyphosphine chloride and 50 mL of ethanol were added to the primary intercalation mixture, and the mixture was stirred at 80° C. for 2 h to obtain a secondary intercalation mixture.

[0045] The secondary intercalation mixture was cooled to room temperature, washed repeatedly with deionized water, filtered, and the upper clear layer was detected with silver nitrate until no white precipitate was produced. It was dried at 100°C for 10 hours, and then crushed through a 200-mesh sieve to obtain organic soil 5#.

[0046] Example 6

[0047] Weigh 40g of sodium montmorillonite and 10g of attapulgite, add them into 1000mL of deionized water and mix them evenly. After stirring at 80°C for 10min, add 15g of octadecyltrimethylammonium chloride, stir and adjust the pH to 7 with 0.01mol / L hydrochloric acid, continue stirring for 1.5h to obtain a primary intercalation mixture.

[0048] 5 g of hexadecyltrimethoxyphosphine chloride and 50 mL of ethanol were added to the primary intercalation mixture, and the mixture was stirred at 80° C. for 2 h to obtain a secondary intercalation mixture.

[0049] The secondary intercalation mixture was cooled to room temperature, washed repeatedly with deionized water, filtered, and the upper clear layer was detected with silver nitrate until no white precipitate was produced. It was dried at 100°C for 10 hours, and then crushed through a 200-mesh sieve to obtain organic soil 6#.

[0050] Example 7

[0051] Weigh 40g of sodium montmorillonite and 10g of attapulgite, add them into 1000mL of deionized water and mix them evenly. After stirring at 80°C for 10min, add 15g of octadecyltrimethylammonium chloride, stir and adjust the pH to 7 with 0.01mol / L hydrochloric acid, continue stirring for 1h to obtain a primary intercalation mixture.

[0052] 5 g of hexadecyltrimethoxyphosphine chloride and 50 mL of ethanol were added to the primary intercalation mixture, and the mixture was stirred at 80° C. for 2 h to obtain a secondary intercalation mixture.

[0053] The secondary intercalation mixture was cooled to room temperature, washed repeatedly with deionized water, filtered, and the upper clear layer was detected with silver nitrate until no white precipitate was produced. It was dried at 100°C for 10 hours, and then crushed through a 200-mesh sieve to obtain organic soil 7#.

[0054] Example 8

[0055] Weigh 40g of sodium montmorillonite and 10g of attapulgite, add them into 1000mL of deionized water and mix them evenly. After stirring at 75°C for 15min, add 15g of octadecyltrimethylammonium chloride, stir and adjust the pH to 7.5 with 0.01mol / L hydrochloric acid, continue stirring for 2h to obtain a primary intercalation mixture.

[0056] 5 g of hexadecyltrimethoxyphosphine chloride and 50 mL of ethanol were added to the primary intercalation mixture, and the mixture was stirred at 75° C. for 2 h to obtain a secondary intercalation mixture.

[0057] The secondary intercalation mixture was cooled to room temperature, washed repeatedly with deionized water, filtered, and the upper clear layer was detected with silver nitrate until no white precipitate was produced. It was dried at 90°C for 10 hours, and then crushed through a 200-mesh sieve to obtain organic soil 8#.

[0058] Example 9

[0059] Weigh 40g of sodium montmorillonite and 10g of attapulgite, add them into 1000mL of deionized water and mix them evenly. After stirring at 85°C for 10min, add 15g of octadecyltrimethylammonium chloride, stir and adjust the pH to 8 with 0.01mol / L hydrochloric acid, continue stirring for 1h to obtain a primary intercalation mixture.

[0060] 5 g of hexadecyltrimethoxyphosphine chloride and 50 mL of ethanol were added to the primary intercalation mixture, and the mixture was stirred at 85° C. for 2 h to obtain a secondary intercalation mixture.

[0061] The secondary intercalation mixture was cooled to room temperature, washed repeatedly with deionized water, filtered, and the upper clear layer was detected with silver nitrate until no white precipitate was produced. It was dried at 90°C for 10 hours, and then crushed through a 200-mesh sieve to obtain organic soil 9#.

[0062] Comparative Example 1

[0063] Weigh 50 g of sodium montmorillonite and add it into 1000 mL of deionized water, mix well, stir at 80 °C for 10 min, add 15 g of hexadecyltrimethylammonium chloride, stir and adjust the pH to 7 with 0.01 mol / L hydrochloric acid, continue stirring for 1.5 h to obtain a primary intercalation mixture.

[0064] 5 g of hexadecyltrimethoxyphosphine chloride and 50 mL of ethanol were added to the primary intercalation mixture, and the mixture was stirred at 80° C. for 2 h to obtain a secondary intercalation mixture.

[0065] The secondary intercalation mixture was cooled to room temperature, washed repeatedly with deionized water, filtered, and the upper clear layer was detected with silver nitrate until no white precipitate was produced. It was dried at 100°C for 10 hours, and then crushed through a 200-mesh sieve to obtain organic soil pair 1#.

[0066] The difference between this comparative example 1 and the above-mentioned embodiment 3 is that attapulgite is not added.

[0067] Comparative Example 2

[0068] Weigh 40 g of sodium montmorillonite and 10 g of attapulgite, add them into 1000 mL of deionized water and mix them evenly. After stirring at 80 °C for 10 min, add 15 g of hexadecyltrimethylammonium chloride, stir and adjust the pH to 7 with 0.01 mol / L hydrochloric acid, continue stirring for 1.5 h to obtain an intercalation mixture.

[0069] The intercalation mixture was cooled to room temperature, washed repeatedly with deionized water, filtered, and the upper clear layer was detected with silver nitrate until no white precipitate was produced. It was dried at 100°C for 10 hours, and then crushed through a 200-mesh sieve to obtain organic soil pair 2#.

[0070] The difference between this comparative example 2 and the above-mentioned example 3 is that hexadecyltrimethoxyphosphine chloride is not used for secondary intercalation modification.

[0071] Comparative Example 3

[0072] Weigh 40g of sodium montmorillonite and 10g of attapulgite, add them into 1000mL of deionized water and mix them evenly. After stirring at 80°C for 10min, add 15g of hexadecyltrimethylammonium chloride, stir and adjust the pH to 7 with 0.01mol / L hydrochloric acid, continue stirring for 1.5h to obtain a primary intercalation mixture.

[0073] 5 g of hexadecyltrimethylammonium chloride and 50 mL of ethanol were added to the primary intercalation mixture, and the mixture was stirred at 80° C. for 2 h to obtain a secondary intercalation mixture.

[0074] The secondary intercalation mixture was cooled to room temperature, washed repeatedly with deionized water, filtered, and the upper clear layer was detected with silver nitrate until no white precipitate was produced. It was dried at 100°C for 10 hours, and then crushed through a 200-mesh sieve to obtain organic soil pair 3#.

[0075] The difference between this comparative example 3 and the above-mentioned example 2 is that the secondary intercalant "hexadecyltrimethoxyphosphonium chloride" is replaced by "hexadecyltrimethylammonium chloride".

[0076] Comparative Example 4

[0077] It is a commercially available organic soil of model YH-918, denoted as 4#.

[0078] Performance testing

[0079] In order to compare the performance of the organic soil obtained in each embodiment and the comparative example, the organic soil obtained in each embodiment and the comparative example is subjected to a suspension performance test, and the test method is as follows:

[0080] Configure the test fluid:

[0081] Add 340mL of No. 0 diesel and 12.0g of Span 80 (accurate to 0.01g, the same below) to a high-stirring cup, stir at 11000r / min for 10 minutes, then add 60mL of water, continue stirring for 10 minutes, add 16.0g of organic soil sample while stirring, and stir at high speed for 20 minutes to obtain the test solution. During the stirring process, ensure that there is no sample adhering to the cup wall, and at the same time, ensure that the test solution temperature is between 25℃ and 30℃.

[0082] Normal temperature test

[0083] The six-speed rotation viscometer is used to test the stable readings of the test liquid at 600r / min, 300r / min and 3r / min, and the apparent viscosity, plastic viscosity and dynamic shear force of the test liquid are calculated. The test temperature is 50±1℃.

[0084] 200℃ aging test

[0085] The prepared test liquid is placed in a high-temperature aging tank, put into a roller heating furnace, and taken out after rolling aging at 200℃ for 16 hours. After high-speed stirring at 11000r / min for 20 minutes, the aging test liquid is obtained. The six-speed rotation viscometer is used to test the stable readings of the test liquid at 600r / min, 300r / min and 3r / min, and the apparent viscosity, plastic viscosity and dynamic shear force of the aging test liquid are calculated. The test temperature is 50±1℃.

[0086] The room temperature and 200° C. aging test results of the above embodiments and comparative examples are shown in the following table.

[0087]

[0088]

[0089] The test data of the examples in the above table show that the organic soil prepared by the method of the present invention has good suspension ability in the oil-based system, and the overall suspension performance is less affected after aging at 200°C, indicating that it has good resistance to high-temperature aging at 200°C.

[0090] It can be seen from the test data of Examples 3, 4 and Comparative Example 1 that, compared with not adding attapulgite, adding a certain amount of attapulgite can effectively improve the thermal stability of the organic soil. However, when the amount of attapulgite added increases, the rheological properties of the organic soil decrease, because attapulgite cannot promote the intercalation modification of bentonite.

[0091] It can be seen from the test data of Example 3 and Comparative Example 2 that even if attapulgite is added to the raw materials, the rheological properties and thermal stability of the organic soil obtained by simply using hexadecyltrimethylammonium chloride for one-time intercalation modification are reduced.

[0092] It can be seen from the test data of Example 3 and Comparative Example 3 that when the secondary intercalant in Example 3 is replaced with hexadecyltrimethylammonium chloride, the rheological properties of the organic soil are increased, and the high temperature resistance of 200° C. is reduced.

[0093] Finally, by comparing the test data of each embodiment with the commercially available organic soil, it can be seen that the organic soil prepared by the method of the present invention has excellent overall performance, and still has a high colloid rate and good viscosity-increasing and shear-enhancing effect after high-temperature aging at 200°C.

[0094] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0095] The above is a detailed introduction to a method for preparing a high-temperature resistant organic soil for drilling fluid provided in an embodiment of the present application. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the technical solution and its core idea of ​​the present application. Ordinary technicians in this field should understand that they can still modify the technical solutions recorded in the aforementioned embodiments, or replace some of the technical features therein with equivalents; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. An organic soil for high temperature resistant drilling fluid, characterized in that: The composition comprises the following components by weight: 50-80 parts of sodium montmorillonite, 10-30 parts of attapulgite, 10-30 parts of long-chain quaternary ammonium salt and 5-15 parts of chelating agent.

2. The high temperature resistant organic soil for drilling fluid according to claim 1, characterized in that: The long-chain quaternary ammonium salt is one of n-alkyl trimethyl ammonium chloride or n-alkyl trimethyl ammonium bromide, wherein n=12-18.

3. The high temperature resistant organic soil for drilling fluid according to claim 1, characterized in that: The chelating agent is one of n-alkyl trimethyl phosphine chloride or n-alkyl trimethyl phosphine bromide, wherein n=(12, 14 or 16).

4. A method for preparing organic soil for high temperature resistant drilling fluid, characterized in that: The steps include: (1) weighing sodium montmorillonite, attapulgite, long-chain quaternary ammonium salt and chelating agent according to weight parts; (2) Mix the weighed sodium montmorillonite and attapulgite with water, stir for 8-15 min at 75-85° C., add the weighed long-chain quaternary ammonium salt, stir and adjust the pH to 7-8, and continue stirring for 0.5-2 h to obtain a primary intercalation mixture; (3) adding ethanol and the weighed chelating agent to the primary intercalation mixture, and continuing to stir at 75-85° C. for 2 h to obtain a secondary intercalation mixture; (4) The secondary intercalation mixed liquid is cooled, filtered, washed, dried, crushed, and sieved to obtain organic soil for high temperature resistant drilling fluid.

5. The method for preparing a high temperature resistant organic soil for drilling fluid according to claim 4, characterized in that: In the step (2), the mixing ratio of sodium montmorillonite, attapulgite and water is (50-80) parts: (10-30) parts: (1000-1500) parts by weight.

6. The method for preparing a high temperature resistant organic soil for drilling fluid according to claim 4, characterized in that: In the step (2), the solution for adjusting pH is a hydrochloric acid solution.

7. The method for preparing a high temperature resistant organic soil for drilling fluid according to claim 4, characterized in that: In the step (3), the ratio of the added amount of ethanol and the added amount of the chelating agent is (50-100) parts: (5-15) parts by weight.

8. The method for preparing a high temperature resistant organic soil for drilling fluid according to claim 4, characterized in that: In the step (4), the washing process is: repeatedly washing with deionized water until no white precipitate is found in the upper clear liquid detected by silver nitrate.

9. The method for preparing a high temperature resistant organic soil for drilling fluid according to claim 4, characterized in that: In the step (4), the drying temperature is 80-100° C. and the drying time is 8-12 hours.

10. The method for preparing a high temperature resistant organic soil for drilling fluid according to claim 4, characterized in that: In the step (4), a 200-mesh sieve is used for sieving.

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