Filtrate reducer as well as preparation method and application thereof

Abstract

The invention provides a filtrate reducer as well as a preparation method and application thereof. The filtrate reducer provided by the invention is obtained by carrying out alkalization treatment on carboxymethyl cellulose and further reacting with dibromophenylethane, dioctadecyl dimethyl ammonium chloride and acrylamide, the temperature resistance reaches 180 DEG C, the salt resistance and calcium resistance are high, the biodegradability is good, the treatment cost of waste slurry is reduced, and the use requirement of an ultra-deep well at the temperature of 150 DEG C or above is met.

Description

Technical Field

[0001] The invention belongs to the technical field of drilling fluid additives, and in particular relates to a fluid loss reducer and a preparation method and application thereof. Background Art

[0002] In the current context of oil and gas exploration, the scale of its development is constantly expanding. Domestic oil and gas exploration targets are gradually focusing on deep wells and ultra-deep wells, and the mining layer is shifting from shallow to deep formations. The performance of drilling fluid directly affects the safety, quality and cost of drilling operations. Among them, fluid loss reducers, as one of the core treatment agents of drilling fluid, can form a thin and dense mud cake on the well wall, thereby reducing the amount of fluid leakage from the drilling fluid system to the well wall. With the continuous improvement of environmental protection requirements, the problem of environmental pollution caused by drilling fluid has gradually received attention, and the research of environmentally friendly fluid loss reducers has become an inevitable trend. However, the high temperature resistance and fluid loss reduction performance of environmentally friendly fluid loss reducers in the existing technology cannot meet the requirements of ultra-deep well formations above 150°C. Summary of the Invention

[0003] In view of the above problems, the purpose of the present invention is to provide an environmentally friendly drilling fluid loss reducer with strong salt and calcium resistance, little effect on the viscosity of the drilling fluid system, and high temperature resistance up to 180°C.

[0004] One aspect of the present invention provides a method for preparing a fluid loss additive, comprising the following steps:

[0005] 1) alkalizing the carboxymethyl cellulose to obtain alkalized carboxymethyl cellulose;

[0006] 2) allowing the alkalized carboxymethyl cellulose to undergo a first reaction with dibromophenylethane and dioctadecyldimethylammonium chloride to obtain an intermediate product;

[0007] 3) allowing the intermediate product to undergo a second reaction with acrylamide to obtain the fluid loss reducer.

[0008] In the present invention, the carboxymethyl cellulose is first subjected to an alkalization treatment, which is beneficial to increasing the reaction speed of step 2). In step 3), acrylamide has the characteristic of hydration and thickening, but the two active hydrogen atoms on the amide group in its structure are easily hydrolyzed and ineffective in the high temperature and high salinity environment of ultra-deep wells, thereby losing the thickening function. Therefore, in step 2), the present invention first introduces a phenethyl structure and a quaternary ammonium salt structure with a long-chain alkyl group into the structure of the alkalized carboxymethyl cellulose. In this way, in step 3), the two active hydrogen atoms on the amide group in the acrylamide can be replaced by an alkyl group, which can effectively inhibit the hydrolysis of the amide group at high temperature and is beneficial to improving the high temperature resistance of the fluid loss reducer.

[0009] According to a specific embodiment of the present invention, the mass ratio of the carboxymethyl cellulose, dibromophenylethane, dioctadecyldimethylammonium chloride and acrylamide is (40-60):(10-18):(12-18):(10-14).

[0010] According to a specific embodiment of the present invention, in step 1), the carboxymethyl cellulose is subjected to the alkalization treatment using an alkalizing agent;

[0011] Preferably, the alkalization treatment is carried out in a solvent;

[0012] Preferably, the solvent is water;

[0013] Preferably, the mass ratio of the carboxymethyl cellulose to water is (40-60):(120-160).

[0014] According to a specific embodiment of the present invention, the mass ratio of the alkalizer to the carboxymethyl cellulose is (10-14):(40-60).

[0015] According to a specific embodiment of the present invention, in step 2), the first reaction is carried out at 100-120° C. for 2-3 hours.

[0016] According to a specific embodiment of the present invention, in step 3), the second reaction is carried out at 60-80° C. for 1.2-2 h.

[0017] According to a specific embodiment of the present invention, the temperature of the alkalization treatment is 40-60° C.; and / or the duration is 1.5-2 h.

[0018] According to a specific embodiment of the present invention, the alkalizing agent is potassium hydroxide and / or sodium hydroxide.

[0019] According to a specific embodiment of the present invention, the alkalizing agent is a mixture of potassium hydroxide and sodium hydroxide.

[0020] According to a specific embodiment of the present invention, the mass ratio of potassium hydroxide to sodium hydroxide is 1:1.

[0021] According to a specific embodiment of the present invention, in step 3), the product obtained by the second reaction is purified to obtain the fluid loss reducer.

[0022] According to a specific embodiment of the present invention, the reaction product obtained by the second reaction is purified by an organic solvent precipitation method, and the obtained precipitate is dried and crushed to obtain the fluid loss reducer;

[0023] Preferably, the organic solvent is at least one of methanol, ethanol and acetone.

[0024] The second aspect of the present invention provides a fluid loss reducer prepared by the method described in the first aspect of the present invention.

[0025] Use of the fluid loss reducer prepared by the method according to one of the present inventions or the fluid loss reducer according to the second present invention in preparing drilling fluid.

[0026] Beneficial effects of the present invention:

[0027] To address the problems of existing fluid loss additives, such as insufficient high-temperature resistance, insufficient high-temperature fluid loss reduction performance, and poor environmental performance, the present invention provides a fluid loss additive, its preparation method, and its use. The fluid loss additive provided by the present invention is obtained by reacting alkalized carboxymethyl cellulose with dibromophenylethane, dioctadecyldimethylammonium chloride, and acrylamide. Compared with existing technologies, it has at least the following advantages:

[0028] 1. The fluid loss additive provided by the present invention, when prepared into a 1 wt% aqueous solution, has an apparent viscosity of 47.9-50.9 mPa.s at room temperature. Addition of the fluid loss additive to a drilling fluid system hardly increases the viscosity of the drilling fluid system.

[0029] 2. The present invention utilizes the synergistic effect of dibromobenzene ethyl and dioctadecyldimethylammonium chloride to enhance the temperature resistance of the fluid loss control agent. The fluid loss of the mixture of the fluid loss control agent and the base slurry provided by the present invention at 180°C is only 11.7-13.9 mL, which is less than 15 mL. The high-temperature fluid loss is low and the temperature resistance reaches 180°C, which can meet the requirements of ultra-deep wells above 150°C.

[0030] 3. The present invention utilizes the synergistic effect of dibromobenzene ethane and dioctadecyldimethylammonium chloride to enhance the salt and calcium resistance of the fluid loss control agent. After aging the mixture of the fluid loss control agent provided by the present invention and base slurry No. 1 containing sodium chloride at 180°C for 16 hours, the fluid loss is mostly within 20 mL; after aging the mixture of the fluid loss control agent provided by the present invention and base slurry No. 2 containing calcium chloride at 180°C for 16 hours, the fluid loss is mostly within 21 mL, showing strong salt and calcium resistance.

[0031] 4. The fluid loss reducer provided by the present invention uses carboxymethyl cellulose as the main raw material. Carboxymethyl cellulose is obtained by carboxylating cellulose. It has little impact on the surrounding environment and good biodegradability. It can meet production environmental protection requirements and also reduce the treatment cost of waste mud. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It reflects the infrared spectrum of the intermediate product obtained in step 2) of Example 1 before the second reaction and the infrared spectrum of the fluid loss reducer obtained after the second reaction in step 3) of Example 1. DETAILED DESCRIPTION

[0033] The present invention will be further described below with reference to examples. However, the examples are merely illustrative and do not limit the present invention in any way.

[0034] The dioctadecyl dimethyl ammonium chloride used in the following examples and comparative examples was purchased from Sinopharm Chemical Reagent Co., Ltd.

[0035] Example 1

[0036] 1) adding 120 g of distilled water to a reaction apparatus, then adding 10 g of an alkalizer (specifically a mixture of potassium hydroxide and sodium hydroxide in a mass ratio of 1:1), and stirring uniformly at a speed of 80 r / min to obtain an alkalizer aqueous solution; adding 40 g of carboxymethyl cellulose to the alkalizer aqueous solution, and performing an alkalization reaction at 40° C. for 1.5 h to complete the alkalization treatment of the carboxymethyl cellulose, thereby obtaining alkalized carboxymethyl cellulose;

[0037] 2) Slowly adding 10 g of dibromophenylethane and 12 g of dioctadecyldimethylammonium chloride to the reaction apparatus containing the alkalized carboxymethyl cellulose in step 1), raising the temperature to 100° C. and reacting at this temperature for 2 h to complete the first reaction and obtain an intermediate product;

[0038] 3) After the temperature drops to 60° C., 10 g of acrylamide is added to the reaction apparatus and reacted with the intermediate product for 1.2 hours to complete the second reaction and obtain a reaction product; methanol is added as an organic solvent to precipitate the reaction product, and the precipitate is collected, dried, and crushed to obtain a fluid loss reducer.

[0039] Example 2

[0040] 1) adding 140 g of distilled water to a reaction apparatus, then adding 12 g of an alkalizer (specifically a mixture of potassium hydroxide and sodium hydroxide in a mass ratio of 1:1), and stirring uniformly at a speed of 90 r / min to obtain an alkalizer aqueous solution; adding 50 g of carboxymethyl cellulose to the alkalizer aqueous solution, and performing an alkalization reaction at 50° C. for 1.7 h to complete the alkalization treatment of the carboxymethyl cellulose, thereby obtaining alkalized carboxymethyl cellulose;

[0041] 2) Slowly adding 14 g of dibromophenylethane and 15 g of dioctadecyldimethylammonium chloride to the reaction apparatus containing the alkalized carboxymethyl cellulose in step 1), raising the temperature to 110° C. and reacting at this temperature for 2.5 h to complete the first reaction and obtain an intermediate product;

[0042] 3) After the temperature drops to 70° C., 12 g of acrylamide is added to the reaction apparatus and reacted with the intermediate product for 1.5 hours to complete the second reaction and obtain a reaction product; methanol is added as an organic solvent to precipitate the reaction product, and the precipitate is collected, dried, and crushed to obtain a fluid loss reducer.

[0043] Example 3

[0044] 1) adding 160 g of distilled water to a reaction apparatus, then adding 14 g of an alkalizer (specifically a mixture of potassium hydroxide and sodium hydroxide in a mass ratio of 1:1), and stirring uniformly at a speed of 100 r / min to obtain an alkalizer aqueous solution; adding 60 g of carboxymethyl cellulose to the alkalizer aqueous solution, and performing an alkalization reaction at 60° C. for 2 h to complete the alkalization treatment of the carboxymethyl cellulose, thereby obtaining alkalized carboxymethyl cellulose;

[0045] 2) Slowly adding 18 g of dibromophenylethane and 18 g of dioctadecyldimethylammonium chloride to the reaction apparatus containing the alkalized carboxymethyl cellulose in step 1), raising the temperature to 120° C. and reacting at this temperature for 3 h to complete the first reaction and obtain an intermediate product;

[0046] 3) After the temperature drops to 80° C., 14 g of acrylamide is added to the reaction apparatus and reacted with the intermediate product for 2 h to complete the second reaction and obtain a reaction product; ethanol is added as an organic solvent to precipitate the reaction product, the precipitate is collected, and then dried and crushed to obtain a fluid loss reducer.

[0047] Example 4

[0048] 1) adding 150 g of distilled water to a reaction apparatus, then adding 11 g of an alkalizer (specifically a mixture of potassium hydroxide and sodium hydroxide in a mass ratio of 1:1), and stirring uniformly at a speed of 95 r / min to obtain an alkalizer aqueous solution; adding 55 g of carboxymethyl cellulose to the alkalizer aqueous solution, and performing an alkalization reaction at 52° C. for 1.8 h to complete the alkalization treatment of the carboxymethyl cellulose, thereby obtaining alkalized carboxymethyl cellulose;

[0049] 2) Slowly adding 16 g of dibromophenylethane and 14 g of dioctadecyldimethylammonium chloride to the reaction apparatus containing the alkalized carboxymethyl cellulose in step 1), raising the temperature to 115° C. and reacting at this temperature for 2.8 h to complete the first reaction and obtain an intermediate product;

[0050] 3) After the temperature drops to 77° C., 11 g of acrylamide is added to the reaction apparatus and reacted with the intermediate product for 1.7 hours to complete the second reaction and obtain a reaction product; ethanol is added as an organic solvent to precipitate the reaction product, and the precipitate is collected, dried, and crushed to obtain a fluid loss reducer.

[0051] Example 5

[0052] 1) adding 145 g of distilled water to a reaction apparatus, then adding 13 g of an alkalizer (specifically a mixture of potassium hydroxide and sodium hydroxide in a mass ratio of 1:1), and stirring uniformly at a speed of 92 r / min to obtain an alkalizer aqueous solution; adding 52 g of carboxymethyl cellulose to the alkalizer aqueous solution, and performing an alkalization reaction at 48° C. for 1.6 h to complete the alkalization treatment of the carboxymethyl cellulose, thereby obtaining alkalized carboxymethyl cellulose;

[0053] 2) Slowly adding 17 g of dibromophenylethane and 13 g of dioctadecyldimethylammonium chloride to the reaction apparatus containing the alkalized carboxymethyl cellulose in step 1), raising the temperature to 111° C. and reacting at this temperature for 2.6 h to complete the first reaction and obtain an intermediate product;

[0054] 3) After the temperature drops to 72° C., 13 g of acrylamide is added to the reaction apparatus and reacted with the intermediate product for 1.6 hours to complete the second reaction and obtain a reaction product; acetone is added as an organic solvent to precipitate the reaction product, and the precipitate is collected, dried, and crushed to obtain a fluid loss reducer.

[0055] Example 6

[0056] 1) adding 155 g of distilled water to a reaction apparatus, then adding 14 g of an alkalizer (specifically a mixture of potassium hydroxide and sodium hydroxide in a mass ratio of 1:1), and stirring uniformly at a speed of 88 r / min to obtain an alkalizer aqueous solution; adding 58 g of carboxymethyl cellulose to the alkalizer aqueous solution, and performing an alkalization reaction at 57° C. for 1.9 h to complete the alkalization treatment of the carboxymethyl cellulose, thereby obtaining alkalized carboxymethyl cellulose;

[0057] 2) Slowly adding 13 g of dibromophenylethane and 17 g of dioctadecyldimethylammonium chloride to the reaction apparatus containing the alkalized carboxymethyl cellulose in step 1), raising the temperature to 118° C. and reacting at this temperature for 3 h to complete the first reaction and obtain an intermediate product;

[0058] 3) After the temperature drops to 78° C., 14 g of acrylamide is added to the reaction apparatus and reacted with the intermediate product for 1.8 hours to complete the second reaction and obtain a reaction product; acetone is added as an organic solvent to precipitate the reaction product, and the precipitate is collected, dried, and crushed to obtain a fluid loss reducer.

[0059] Comparative Example 1

[0060] The difference from Example 6 is that dibromobenzene ethane and dioctadecyldimethylammonium chloride are not added. Other steps are the same as in Example 6 to obtain a fluid loss reducer.

[0061] Comparative Example 2

[0062] The difference from Example 6 is that no dibromobenzene ethane is added. Other processes are the same as in Example 6 to obtain a fluid loss reducer.

[0063] Comparative Example 3

[0064] The difference from Example 6 is that no dioctadecyldimethylammonium chloride is added. Other steps are the same as in Example 6 to obtain a fluid loss reducer.

[0065] Comparative Example 4

[0066] The difference from Example 6 is that acrylamide is not added. Other processes are the same as in Example 6 to obtain a fluid loss reducer.

[0067] Fluid loss additive evaluation

[0068] 1. Infrared spectrum determination of intermediate products and fluid loss reducer before and after the second reaction

[0069] Taking Example 1 as an example, the intermediate product obtained in step 2) of Example 1 and the fluid loss reducer obtained in step 3) were measured by Fourier infrared spectroscopy (FTIR). Figure 1 .

[0070] Figure 1 The NH stretching vibration peak of the intermediate product before the second reaction is at 3441 cm -1 Compared with the intermediate product before the second reaction, the NH stretching vibration peak of the fluid loss reducer obtained after the second reaction is from 3441 cm -1 Transfer to 3415cm -1 At , the characteristic peak of NH stretching vibration red-shifted, indicating that the molecular structure of the fluid loss agent has changed compared with the intermediate product, proving that acrylamide has been successfully integrated into the structure of the fluid loss agent.

[0071] Infrared spectroscopy was performed on the intermediate product obtained in step 2) of each of Examples 2 to 6 and the fluid loss reducer obtained in step 3). It was found that in any of Examples 2 to 6, the NH stretching vibration characteristic peak of the fluid loss reducer obtained after the second reaction was red-shifted compared to the intermediate product before the second reaction, indicating that the fluid loss reducer prepared in Examples 2 to 6 had a structural change compared to the intermediate product, and acrylamide in Examples 2 to 6 was successfully integrated into the structure of the fluid loss reducer.

[0072] 2. Determination of apparent viscosity of filtrate reducer aqueous solution

[0073] The fluid loss control agents prepared in Examples 1 to 6 and Comparative Examples 1 to 4 were respectively prepared into aqueous solutions, and then the apparent viscosities of the fluid loss control agent aqueous solutions were measured.

[0074] (1) Preparation of filtrate reducer aqueous solution

[0075] Measure 500 mL of deionized water, add 5 g of fluid loss agent under high-speed stirring, and stir for 8 minutes to obtain a fluid loss agent aqueous solution;

[0076] The fluid loss control agents prepared in Examples 1 to 6 and Comparative Examples 1 to 4 were respectively prepared into fluid loss control agent aqueous solutions according to the above method.

[0077] (2) Apparent viscosity measurement

[0078] The Φ600 readings of the various fluid loss reducer aqueous solutions prepared in (1) were measured at room temperature (i.e., 25° C.) using a six-speed viscometer and the apparent viscosities were calculated. The results are shown in Table 1.

[0079] Table 1. Apparent viscosity of fluid loss additive aqueous solution

[0080] Serial number Apparent viscosity / (mPa.s) Example 1 47.9 Example 2 49.8 Example 3 50.9 Example 4 49.2 Example 5 48.4 Example 6 50.4 Comparative Example 1 44.6 Comparative Example 2 47.8 Comparative Example 3 46.3 Comparative Example 4 46.1

[0081] Table 1 shows that the apparent viscosity of the aqueous solutions of the fluid loss control agents prepared in Examples 1 to 6 at room temperature with a mass fraction of 1 wt % is 47.9-50.9 mPa.s. The suitable apparent viscosity means that the fluid loss control agents prepared in the present invention hardly increase the viscosity of the drilling fluid system after being added to the drilling fluid system.

[0082] 3. Determination of fluid loss of fluid loss reducer at 180℃ high temperature and high pressure

[0083] ⅰBase slurry preparation

[0084] Deionized water, sodium bentonite for test slurry and anhydrous sodium carbonate were mixed in a mass ratio of 400:20:1, and stirred at 300 rpm for 20 min. During this period, stirring was stopped at least twice to scrape off the sodium bentonite for test slurry adhering to the container wall. After sealed and cured at room temperature for 24 h, the base slurry was obtained.

[0085] ii) Take 400 mL of the base slurry prepared in step i, add 12.0 g of fluid loss agent, and stir at 1500 rpm for 20 minutes. Stop stirring at least twice during this period to scrape off the fluid loss agent adhering to the container wall to obtain a mixture of fluid loss agent and base slurry;

[0086] The fluid loss reducers prepared in Examples 1 to 6 and Comparative Examples 1 to 4 were respectively prepared according to the above method to obtain a mixture of the fluid loss reducer and base slurry;

[0087] ⅲ The fluid loss of the mixture of the fluid loss reducer and the base slurry prepared in ⅱ was measured under the conditions of 180°C and 3450 kPa. The specific results are shown in Table 2.

[0088] Table 2. 180℃ fluid loss of mixture of fluid loss additive and base slurry

[0089] Serial number 180℃ Filtration loss / mL Example 1 13.6 Example 2 11.7 Example 3 13.9 Example 4 12.9 Example 5 13.4 Example 6 12.8 Comparative Example 1 51.6 Comparative Example 2 18.7 Comparative Example 3 37.6 Comparative Example 4 42.3

[0090] Table 2 shows that the mixtures of the fluid loss reducers and base slurry prepared in Examples 1 to 6 have a fluid loss of only 11.7-13.9 mL at 180°C, all below 15 mL, and a low high-temperature fluid loss. This demonstrates that the fluid loss reducer provided by the present invention has good temperature resistance and can withstand high temperatures of 180°C. From the formula point of view, compared with Example 6: no dibromobenzene ethane and dioctadecyl dimethyl ammonium chloride were added in Comparative Example 1, no dibromobenzene ethane was added in Comparative Example 2, and no dioctadecyl dimethyl ammonium chloride was added in Comparative Example 3. The 180°C filtration loss of the mixture of the fluid loss reducer and the base slurry prepared in Comparative Example 1 increased by 303% compared with that in Example 6, the 180°C filtration loss of the mixture of the fluid loss reducer and the base slurry prepared in Comparative Example 2 increased by 46.1% compared with that in Example 6, and the 180°C filtration loss of the mixture of the fluid loss reducer and the base slurry prepared in Comparative Example 3 increased by 193.8% compared with that in Example 6. The growth rate of the fluid loss reduction in Comparative Example 1 compared with Example 6 is greater than the sum of the growth rates of the fluid loss reduction in Comparative Example 2 and Comparative Example 3 compared with Example 6, indicating that in the preparation process of the fluid loss reducer provided by the present invention, dibromobenzene ethane and dioctadecyl dimethyl ammonium chloride synergize to enhance the fluid loss reduction performance of the fluid loss reducer at high temperature. Compared with Example 6, the filtration loss of the mixture of the fluid loss additive and base slurry prepared in Comparative Example 4 without adding acrylamide at 180°C increased significantly, indicating that the fluid loss additive prepared in Comparative Example 4 without adding acrylamide has poor temperature resistance.

[0091] 4. Determination of filtration loss when adding NaCl or CaCl2

[0092] A. Base slurry preparation

[0093] Deionized water, sodium chloride, sodium bentonite for test slurry and anhydrous sodium carbonate were mixed in a mass ratio of 400:40:20:1, and stirred at 300 rpm for 20 minutes. During this period, stirring was stopped at least twice to scrape off the sodium bentonite for test slurry adhering to the container wall. After sealed and cured at room temperature for 24 hours, the No. 1 base slurry was obtained.

[0094] Mix deionized water, calcium chloride, sodium bentonite for test slurry and anhydrous sodium carbonate in a mass ratio of 400:6:20:1, and stir at 300 rpm for 20 minutes. Stop stirring at least twice during this period to scrape off the sodium bentonite for test slurry adhering to the container wall. After sealed and cured at room temperature for 24 hours, the No. 2 base slurry is obtained.

[0095] B. Take 400 mL of the No. 1 base slurry prepared in A, add 16.0 g of fluid loss additive while stirring, and stir at high speed for 20 minutes. During this period, stop stirring at least twice to scrape off the fluid loss additive adhering to the container wall to obtain a mixture of No. 1 base slurry and fluid loss additive;

[0096] The fluid loss reducers prepared in Examples 1 to 6 and Comparative Examples 1 to 4 were respectively formulated according to the above method to obtain a mixture of base slurry No. 1 and the fluid loss reducer.

[0097] C. Take 400 mL of the No. 2 base slurry prepared in A, add 16.0 g of fluid loss additive while stirring, and stir at high speed for 20 minutes. During this period, stop stirring at least twice to scrape off the fluid loss additive adhering to the container wall to obtain a mixture of No. 2 base slurry and fluid loss additive;

[0098] The fluid loss additives prepared in Examples 1 to 6 and Comparative Examples 1 to 4 were respectively formulated according to the above method to obtain a mixture of No. 2 base slurry and the fluid loss additive.

[0099] D. The mixture of No. 1 base slurry and fluid loss additive, and the mixture of No. 2 base slurry and fluid loss additive prepared in B and C were respectively transferred to an aging tank. After aging at 180°C for 16 hours, the mixtures were taken out and the fluid loss was measured at room temperature. The specific results are shown in Table 3.

[0100] Table 3. Fluid loss of the mixture of No. 1 base slurry and fluid loss agent, and the mixture of No. 2 base slurry and fluid loss agent after aging at 180℃ for 16 hours

[0101]

[0102]

[0103] Table 3 shows that after the fluid loss control agents prepared in Examples 1 to 6 were mixed with base slurry No. 1 containing sodium chloride and aged at 180°C for 16 hours, the fluid loss was mostly within 20 mL. Similarly, after the fluid loss control agents prepared in Examples 1 to 6 were mixed with base slurry No. 2 containing calcium chloride and aged at 180°C for 16 hours, the fluid loss was mostly within 21 mL. This demonstrates that the fluid loss control agents prepared in the present invention have excellent salt and calcium tolerance. From the formula point of view, compared with Example 6: no dibromobenzene ethane and dioctadecyl dimethyl ammonium chloride were added in Comparative Example 1, no dibromobenzene ethane was added in Comparative Example 2, and no dioctadecyl dimethyl ammonium chloride was added in Comparative Example 3. The results are as follows: (1) the filtration loss of the mixture of the filtration loss agent prepared in Comparative Example 1 and the No. 1 base slurry containing sodium chloride after aging at 180°C for 16 hours increased by 230.9% compared with that in Example 6, the filtration loss of the mixture of the filtration loss agent prepared in Comparative Example 2 and the No. 1 base slurry containing sodium chloride after aging at 180°C for 16 hours increased by 31.5% compared with that in Example 6, and the filtration loss of the mixture of the filtration loss agent prepared in Comparative Example 3 and the No. 1 base slurry containing sodium chloride after aging at 180°C for 16 hours increased by 63.1% compared with that in Example 6. The filtration loss growth rate of Comparative Example 1 compared with Example 6 is greater than that of Comparative Example 2 and Comparative Example 3 compared with Example 6. The sum of the growth rates of filtration loss; (2) the filtration loss of the mixture of the filtration reducer prepared in Comparative Example 1 and the No. 2 base slurry containing calcium chloride after aging at 180°C for 16 hours increased by 163.3% compared with that in Example 6, the filtration loss of the mixture of the filtration reducer prepared in Comparative Example 2 and the No. 2 base slurry containing calcium chloride after aging at 180°C for 16 hours increased by 17.1% compared with that in Example 6, and the filtration loss of the mixture of the filtration reducer prepared in Comparative Example 3 and the No. 2 base slurry containing calcium chloride after aging at 180°C for 16 hours increased by 36.2% compared with that in Example 6. The growth rate of filtration loss of Comparative Example 1 compared with Example 6 is greater than the sum of the growth rates of filtration loss of Comparative Example 2 and Comparative Example 3 compared with Example 6, indicating that in the preparation process of the filtration loss reducer provided by the present invention, dibromobenzene ethane and dioctadecyldimethylammonium chloride synergize to enhance the salt resistance and calcium resistance of the filtration loss reducer. Compared with Example 6, in Comparative Example 4, no acrylamide was added. The mixture of the prepared fluid loss reducer and base slurry No. 1 containing sodium chloride or base slurry No. 2 containing calcium chloride was aged at 180°C for 16 hours, and the fluid loss increased compared with that in Example 6, indicating that the fluid loss reducer prepared in Comparative Example 4 had poor salt and calcium resistance.

[0104] Although the present invention has been described with reference to specific embodiments, those skilled in the art will appreciate that various modifications may be made without departing from the true spirit and scope of the invention. Furthermore, the subject matter, spirit, and scope of the invention may be modified in various ways to adapt to specific circumstances, materials, combinations of materials, and methods. All such modifications are intended to be within the scope of the claims.

Claims

1. A method for preparing a fluid loss additive, comprising the following steps: 1) alkalizing the carboxymethyl cellulose to obtain alkalized carboxymethyl cellulose; 2) allowing the alkalized carboxymethyl cellulose to undergo a first reaction with dibromophenylethane and dioctadecyldimethylammonium chloride to obtain an intermediate product; 3) allowing the intermediate product to undergo a second reaction with acrylamide to obtain the fluid loss reducer.

2. The method according to claim 1, characterized in that The mass ratio of the carboxymethyl cellulose, dibromophenylethane, dioctadecyldimethylammonium chloride and acrylamide is (40-60):(10-18):(12-18):(10-14).

3. The method according to claim 1 or 2, characterized in that In step 1), the carboxymethyl cellulose is subjected to the alkalization treatment using an alkalizing agent.

4. The method according to claim 3, characterized in that The mass ratio of the alkalizer to the carboxymethyl cellulose is (10-14):(40-60).

5. The method according to any one of claims 1 to 4, characterized in that In step 2), the first reaction is carried out at 100-120° C. for 2-3 h.

6. The method according to any one of claims 1 to 5, characterized in that In step 3), the second reaction is carried out at 60-80° C. for 1.2-2 h.

7. The method according to any one of claims 1 to 6, characterized in that The alkalization treatment may be performed at a temperature of 40-60° C. and / or for a duration of 1.5-2 hours.

8. The method according to claim 3 or 4, characterized in that The alkalizing agent is potassium hydroxide and / or sodium hydroxide.

9. A fluid loss additive prepared by the method according to any one of claims 1 to 8.

10. Use of the fluid loss reducer prepared according to the method of any one of claims 1 to 8 or the fluid loss reducer according to claim 9 in preparing drilling fluid.

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