Salt-resistant and calcium-resistant fluid loss reducer for water-based drilling fluid and preparation method thereof

Abstract

The present invention relates to the technical field of oilfield chemical additives, and is a salt-resistant and calcium-resistant fluid loss reducer for water-based drilling fluid and a preparation method thereof. The raw materials include bone glue, chloromethyl naphthalene, diethylenetriamine, neopentyl glycol diacrylate, potassium hydroxide, and hydrogen peroxide. The bone glue is added to deionized water, potassium hydroxide is added, nitrogen is introduced and heated to obtain a first viscous solution; chloromethyl naphthalene, diethylenetriamine and hydrogen peroxide are then added, the pH value of the solution is adjusted, and stirring is performed to obtain a mixed solution; a required amount of initiator neopentyl glycol diacrylate is added, and the mixture is heated and stirred to react to obtain a second viscous solution; the solution is poured out, dried and ground to obtain the product. The preparation method of the present invention is simple, the raw materials used are low in cost, the preparation process is simple and easy to obtain, the pollution to the environment is small, and the product has good temperature resistance, salt resistance and calcium resistance. It can significantly improve the stability of the well wall during drilling, improve the fluid loss and wall-building properties of the drilling fluid, and has a good fluid loss reduction effect.

Description

Technical Field

[0001] The invention relates to the technical field of oilfield chemical additives, in particular to a salt-resistant and calcium-resistant fluid loss reducer for water-based drilling fluid and a preparation method thereof. Background Art

[0002] During the exploration and development of oil and gas resources, as formations are drilled open, water in the drilling fluid flows deeper into the formation due to pressure differentials. The formation rocks swell and disperse upon contact with water, causing wellbore instability or reservoir damage, seriously impacting drilling safety and oil and gas production. Adding fluid loss additives to the drilling fluid can stabilize the fluid's performance, reduce the loss of harmful fluids into the geological formation, improve wellbore stability, and effectively ensure safe oilfield production.

[0003] With the continuous increase in mining volume and the continuous improvement of exploration technology, various complex geological environments have placed greater and higher requirements on drilling fluids and various drilling fluid additives, such as fluid loss reducers. For example, when drilling into complex formations such as deep layers and salt-gypsum layers, fluid loss reducers must have high temperature resistance, salt resistance, and calcium tolerance. Currently, commonly used water-based drilling fluid systems, such as potassium-calcium polyamine organic salt drilling fluids and calcium-based polysulfone drilling fluids, which use calcium oxide or calcium chloride as a calcium source, generally have calcium ion levels below 1000ppm, resulting in insufficient resistance to contamination in calcium-gypsum layers. This is particularly evident in the poor fluid loss reduction effect of existing salt- and calcium-resistant fluid loss reducers when the calcium and magnesium ion concentration reaches 5000ppm. The addition of large amounts of treatment agents results in high costs and difficulty in controlling rheological properties.

[0004] While oil-based drilling fluid systems offer advantages in terms of inhibitory properties and pollution resistance, they suffer from poor water resistance and high costs, making them unsuitable for the rapid drilling requirements of upper formations in some regions. Currently, some fluid loss additives with salt and calcium tolerance are available on the market. These are mostly based on organic polymers with inorganic compounds and auxiliary polymers, but they suffer from insufficient calcium tolerance, high costs, and complex preparation. Summary of the Invention

[0005] The present invention provides a salt-resistant and calcium-resistant fluid loss reducer for water-based drilling fluid and a preparation method thereof, which overcomes the deficiencies of the above-mentioned prior art and can effectively solve the problems of poor fluid loss reduction effect, large amount of treatment agent added, high cost, difficult rheological control and complex preparation of the existing salt-resistant and calcium-resistant fluid loss reducers in oil-based drilling fluid systems.

[0006] One of the technical solutions of the present invention is achieved through the following measures: a salt-resistant and calcium-resistant fluid loss reducer for water-based drilling fluid, wherein the raw materials include, by weight, 35 to 60 parts of bone glue, 15 to 25 parts of chloromethyl naphthalene, 25 to 40 parts of diethylenetriamine, 0 to 1 part of neopentyl glycol diacrylate, 0.3 to 1 part of potassium hydroxide, and 15 to 30 parts of hydrogen peroxide.

[0007] The following is a further optimization and / or improvement of one of the above-mentioned technical solutions:

[0008] The above raw materials include, by mass, 40 to 55 parts of bone glue, 15 to 20 parts of chloromethyl naphthalene, 30 to 40 parts of diethylenetriamine, 20 to 30 parts of neopentyl glycol diacrylate, 0.5 to 1 part of potassium hydroxide, and 20 to 30 parts of hydrogen peroxide.

[0009] The above raw materials include, by mass, 50 to 55 parts of bone glue, 15 to 18 parts of chloromethyl naphthalene, 30 to 35 parts of diethylenetriamine, 25 to 30 parts of neopentyl glycol diacrylate, 0.5 to 0.8 parts of potassium hydroxide, and 20 to 25 parts of hydrogen peroxide.

[0010] The above preparation method is as follows: first, adding deionized water to a reaction container, then adding the required amount of bone glue to the deionized water, slowly stirring for 1 hour, then adding potassium hydroxide, passing nitrogen, heating to 90° C. to 95° C., and slowly stirring until dissolved to obtain a first viscous solution; second, adding the required amount of chloromethylnaphthalene, diethylenetriamine and hydrogen peroxide to the first viscous solution in sequence, slowly passing nitrogen into the viscous aqueous solution, adding a pH adjuster to adjust the pH value of the solution to 9 to 12, and stirring at 75° C. to 90° C. for 4 to 6 hours to obtain a mixed solution; third, adding the required amount of initiator neopentyl glycol diacrylate to the mixed solution, heating to 150° C., stirring until it becomes viscous and reacting to obtain a second viscous solution; fourth, pouring out the second viscous solution, drying it, and grinding it to obtain a salt-resistant and calcium-resistant fluid loss reducer for water-based drilling fluid.

[0011] In the first step above, the ratio of the mass of deionized water to the total mass of raw materials is 3:1.

[0012] In the second step, the added hydrogen peroxide has a mass percentage concentration of 25%, the nitrogen is introduced for 2 to 3 hours, and the added pH regulator is a potassium hydroxide solution with a mass percentage concentration of 45%.

[0013] In the third step, the reaction time is 4 to 6 hours.

[0014] In the fourth step, the second viscous solution is placed in a constant temperature forced air drying oven and dried at 105° C. to 125° C.

[0015] The stirring speeds in the first, second and third steps are all 300 r / min to 400 r / min.

[0016] The second technical solution of the present invention is achieved by the following measures: a preparation method of a salt-resistant and calcium-resistant fluid loss reducer for water-based drilling fluid, which is carried out according to the following method: a first step, adding deionized water to a reaction container, and then adding the required amount of bone glue to the deionized water, slowly stirring for 1 hour, then adding potassium hydroxide, passing nitrogen, heating to 90° C. to 95° C., and slowly stirring until dissolved to obtain a first viscous solution; a second step, sequentially adding the required amount of chloromethylnaphthalene, diethylenetriamine and hydrogen peroxide to the first viscous solution, slowly passing nitrogen into the viscous aqueous solution, and adding a pH regulator to adjust the pH value of the solution to 9 to 12, stirring at 75° C. to 90° C. for 4 to 6 hours to obtain a mixed solution; a third step, adding the required amount of initiator neopentyl glycol diacrylate to the mixed solution, heating to 150° C., stirring until it becomes viscous to react, and obtaining a second viscous solution; a fourth step, pouring out the second viscous solution, drying it, and grinding it to obtain a salt-resistant and calcium-resistant fluid loss reducer for water-based drilling fluid.

[0017] The excellent effects of the present invention are as follows:

[0018] 1. The present invention uses conventional monomers as raw materials when preparing polymers, and the molecular weight of the product is high;

[0019] 2. The product prepared by the present invention has good compatibility with conventional water-based drilling fluid systems;

[0020] 3. The components of the fluid loss reducer of the present invention cooperate with each other, so that the fluid loss reducer has good temperature resistance, salt resistance and calcium resistance, and can significantly improve the stability of the well wall during drilling, improve the fluid loss and wall building properties of the drilling fluid, and have a good fluid loss reduction effect;

[0021] 4. The preparation method of the fluid loss reducer of the present invention is simple, the raw materials used are low in cost, the preparation process is simple and easy to obtain, and the environmental pollution is small. It is an environmentally friendly fluid loss reducer. DETAILED DESCRIPTION

[0022] The present invention is not limited to the following embodiments; specific implementation methods may be determined based on the technical solutions and actual conditions of the present invention. Unless otherwise specified, the various chemical reagents and chemicals mentioned in the present invention are all known and commonly used chemical reagents and chemicals in the prior art; unless otherwise specified, percentages in the present invention are by mass; and unless otherwise specified, solutions in the present invention are all aqueous solutions in which the solvent is water.

[0023] The present invention will be further described below in conjunction with the embodiments:

[0024] Example 1: The salt-resistant and calcium-resistant fluid loss reducer for water-based drilling fluid comprises, by weight, 35 to 60 parts of bone glue, 15 to 25 parts of chloromethyl naphthalene, 25 to 40 parts of diethylenetriamine, 0 to 1 part of neopentyl glycol diacrylate, 0.3 to 1 part of potassium hydroxide, and 15 to 30 parts of hydrogen peroxide.

[0025] The raw materials of the present invention include bone glue, which is hydrolyzed under alkaline conditions, and its macromolecular peptide chains are broken to form shorter amino acid molecules. Through grafting modification, a network-like three-dimensional structure is formed, thereby improving the rigid structure of the fluid loss reducer and having good stability under high temperature and high salt conditions. The raw materials of the present invention include chloromethylnaphthalene monomers, which have multiple methyl groups, methylene groups and ester groups. Due to the presence of some hydrophobic groups, the molecular chains of the monomers can form an association structure through interionic or intermolecular interaction forces under ultra-high temperature environments, thereby accelerating the solubility of the fluid loss reducer molecules under high temperature environments and improving the fluid loss reduction effect. The raw materials of the present invention also include diethylenetriamine, and the multiple functional groups formed by the cations and other active functional groups of the diethylenetriamine enable the molecule to effectively improve the salt and calcium resistance of the fluid loss reducer.

[0026] The raw materials in the present invention are all commercially available commodities.

[0027] Example 2: The salt-resistant and calcium-resistant fluid loss reducer for water-based drilling fluid comprises, by weight, 35 or 60 parts of bone glue, 15 or 25 parts of chloromethyl naphthalene, 25 or 40 parts of diethylenetriamine, 0 or 1 part of neopentyl glycol diacrylate, 0.3 or 1 part of potassium hydroxide, and 15 or 30 parts of hydrogen peroxide.

[0028] Example 3: As an optimization of the above example, the raw materials include 40 to 55 parts of bone glue, 15 to 20 parts of chloromethyl naphthalene, 30 to 40 parts of diethylenetriamine, 0 to 1 part of neopentyl glycol diacrylate, 0.5 to 1 part of potassium hydroxide, and 20 to 30 parts of hydrogen peroxide in parts by mass.

[0029] Example 4: As an optimization of the above example, the raw materials include 50 to 55 parts of bone glue, 15 to 18 parts of chloromethyl naphthalene, 30 to 35 parts of diethylenetriamine, 0 to 1 part of neopentyl glycol diacrylate, 0.5 to 0.8 parts of potassium hydroxide, and 20 to 25 parts of hydrogen peroxide in parts by mass.

[0030] Example 5: As an optimization of the above embodiment, the salt-resistant and calcium-resistant fluid loss reducer for water-based drilling fluid is prepared according to the following method: the first step is to add deionized water to the reaction vessel, and then add the required amount of bone glue to the deionized water, slowly stir for 1 hour, then add potassium hydroxide, pass nitrogen, heat to 90°C to 95°C, and slowly stir until dissolved to obtain a first viscous solution; the second step is to add the required amount of chloromethylnaphthalene, diethylenetriamine and hydrogen peroxide to the first viscous solution in sequence, slowly pass nitrogen into the viscous aqueous solution, and add a pH regulator to adjust the pH value of the solution to 9 to 12, and stir at 75°C to 90°C for 4 to 6 hours to obtain a mixed solution; the third step is to add the required amount of initiator neopentyl glycol diacrylate to the mixed solution, heat to 150°C, stir until it is viscous and react to obtain a second viscous solution; the fourth step is to pour out the second viscous solution, dry it, and grind it to obtain a salt-resistant and calcium-resistant fluid loss reducer for water-based drilling fluid.

[0031] The reaction container in the present invention can be a three-necked flask.

[0032] Example 6: As an optimization of the above example, in the first step, the ratio of the mass of deionized water to the total mass of raw materials is 3:1.

[0033] Example 7: As an optimization of the above example, in the second step, the mass percentage concentration of the added hydrogen peroxide is 25%, the time of introducing nitrogen is 2h to 3h, and the pH regulator added is a potassium hydroxide solution with a mass percentage concentration of 45%.

[0034] Example 8: As an optimization of the above example, in the third step, the reaction time is 4 to 6 hours.

[0035] Example 9: As an optimization of the above example, in the fourth step, the second viscous solution is placed in a constant temperature blast drying oven and dried at 105°C to 125°C.

[0036] Example 10: As an optimization of the above example, the stirring speeds in the first step, the second step and the third step are all 300 r / min to 400 r / min.

[0037] Example 11: The preparation method of the salt-resistant and calcium-resistant fluid loss reducer for water-based drilling fluid is carried out according to the following method: the first step is to add deionized water into a three-necked flask, and then the required amount of bone glue is added to the deionized water, slowly stirred for 1 hour, and then potassium hydroxide is added, nitrogen is introduced, heated to 90°C, and slowly stirred until dissolved to obtain a first viscous solution; the second step is to add the required amount of chloromethylnaphthalene, diethylenetriamine and hydrogen peroxide to the first viscous solution in sequence, nitrogen is slowly introduced into the viscous aqueous solution, and a pH regulator is added to adjust the pH value of the solution to 9 to 12, and stirred at 75°C for 4 to 6 hours to obtain a mixed solution; the third step is to add the required amount of initiator neopentyl glycol diacrylate to the mixed solution, and heat it to 150°C, stir it until it becomes viscous, and react to obtain a second viscous solution; the fourth step is to pour out the second viscous solution, dry it, and grind it to obtain a white powder of the salt-resistant and calcium-resistant fluid loss reducer for water-based drilling fluid.

[0038] The present invention first hydrolyzes bone gelatin under alkaline conditions to split and degrade the macromolecular peptide chains into shorter amino acids. Chloromethylnaphthalene and diethylenetriamine are then added, and monomers with different functional groups are polymerized to form a network structure with a -CC- backbone and grafted with rigid cationic groups. This network structure enhances the rigidity of the polymer and provides good stability in high-temperature, high-salt environments. The resulting salt- and calcium-resistant fluid loss reducer for water-based drilling fluid has excellent solubility, good compatibility with other drilling fluid additives, good salt- and calcium-resistant fluid loss reduction properties, good thermal stability, simple preparation, and low cost.

[0039] Example 12: The salt-resistant and calcium-resistant fluid loss reducer for water-based drilling fluid was prepared according to the following method: a first step, 1L of deionized water was added to a three-necked flask, and then 35g of bone glue was added to the deionized water, slowly stirred for 1 hour, and then 0.8g of potassium hydroxide was added, nitrogen was introduced, heated to 90°C, and slowly stirred until dissolved to obtain a first viscous solution; a second step, 25g of chloromethylnaphthalene, 30g of diethylenetriamine and 20g of hydrogen peroxide were added to the first viscous solution in sequence, nitrogen was slowly introduced into the viscous aqueous solution, and a pH regulator was added to adjust the pH value of the solution to 11, and stirred at 75°C for 4 hours to obtain a mixed solution; a third step, 1g of neopentyl glycol diacrylate was added to the mixed solution, and the mixture was heated to 150°C, stirred until it was viscous and reacted to obtain a second viscous solution; a fourth step, the second viscous solution was poured out, dried, and ground to obtain a white powdery water-based salt-resistant and calcium-resistant fluid loss reducer for drilling fluid.

[0040] Example 13: The salt-resistant and calcium-resistant fluid loss reducer for water-based drilling fluid was prepared according to the following method: the first step was to add 1L of deionized water to a three-necked flask, and then 35g of bone glue was added to the deionized water, slowly stirred for 1 hour, and then 0.8g of potassium hydroxide was added, nitrogen was introduced, heated to 90°C, and slowly stirred until dissolved to obtain a first viscous solution; the second step was to add 25g of chloromethylnaphthalene, 30g of diethylenetriamine and 20g of hydrogen peroxide in sequence to the first viscous solution, nitrogen was slowly introduced into the viscous aqueous solution, and a pH regulator was added to adjust the pH value of the solution to 11, and stirred at 75°C for 5 hours to obtain a mixed solution; the third step was to add 1.0g of neopentyl glycol diacrylate to the mixed solution, and heated to 150°C, stirred until it was viscous to react, and obtain a second viscous solution; the fourth step was to pour out the second viscous solution, dry it, and grind it to obtain a white powdery water-based salt-resistant and calcium-resistant fluid loss reducer for drilling fluid.

[0041] Example 14: The salt-resistant and calcium-resistant fluid loss reducer for water-based drilling fluid was prepared according to the following method: a first step, 1L of deionized water was added to a three-necked flask, and 40g of bone glue was added to the deionized water, slowly stirred for 1 hour, and then 1.0g of potassium hydroxide was added, nitrogen was introduced, heated to 95°C, and slowly stirred until dissolved to obtain a first viscous solution; a second step, 30g of chloromethylnaphthalene, 25g of diethylenetriamine and 20g of hydrogen peroxide were added to the first viscous solution in sequence, nitrogen was slowly introduced into the viscous aqueous solution, and a pH regulator was added to adjust the pH value of the solution to 11, and stirred at 80°C for 5 hours to obtain a mixed solution; a third step, 0.80g of neopentyl glycol diacrylate was added to the mixed solution, and the mixture was heated to 150°C, stirred until it became viscous and reacted to obtain a second viscous solution; a fourth step, the second viscous solution was poured out, dried, and ground to obtain a white powdery water-based salt-resistant and calcium-resistant fluid loss reducer for drilling fluid.

[0042] Example 15: The salt-resistant and calcium-resistant fluid loss reducer for water-based drilling fluid was prepared according to the following method: the first step was to add 1L of deionized water to a three-necked flask, and then 35g of bone glue was added to the deionized water, slowly stirred for 1 hour, and then 1.0g of potassium hydroxide was added, nitrogen was introduced, heated to 95°C, and slowly stirred until dissolved to obtain a first viscous solution; the second step was to add 25g of chloromethylnaphthalene, 25g of diethylenetriamine and 25g of hydrogen peroxide in sequence to the first viscous solution, nitrogen was slowly introduced into the viscous aqueous solution, and a pH regulator was added to adjust the pH value of the solution to 12, and stirred at 80°C for 5 hours to obtain a mixed solution; the third step was to add 0.75g of neopentyl glycol diacrylate to the mixed solution, and heated to 150°C, stirred until a viscous state was reacted to obtain a second viscous solution; the fourth step was to pour out the second viscous solution, dry it, and grind it to obtain a white powdery water-based salt-resistant and calcium-resistant fluid loss reducer for drilling fluid.

[0043] Example 16: The salt-resistant and calcium-resistant fluid loss reducer for water-based drilling fluid was prepared according to the following method: the first step was to add 1L of deionized water to a three-necked flask, and then 35g of bone glue was added to the deionized water, slowly stirred for 1 hour, and then 0.8g of potassium hydroxide was added, nitrogen was introduced, heated to 90°C, and slowly stirred until dissolved to obtain a first viscous solution; the second step was to add 30g of chloromethylnaphthalene, 25g of diethylenetriamine and 15g of hydrogen peroxide in sequence to the first viscous solution, nitrogen was slowly introduced into the viscous aqueous solution, and a pH regulator was added to adjust the pH value of the solution to 12, and stirred at 90°C for 5 hours to obtain a mixed solution; the third step was to add 0.9g of neopentyl glycol diacrylate to the mixed solution, and heated to 150°C, stirred until it was viscous to react, and obtain a second viscous solution; the fourth step was to pour out the second viscous solution, dry it, and grind it to obtain a white powdery water-based salt-resistant and calcium-resistant fluid loss reducer for drilling fluid.

[0044] Example 17: The salt-resistant and calcium-resistant fluid loss reducer for water-based drilling fluid was prepared according to the following method: the first step was to add 1L of deionized water to a three-necked flask, and then 45g of bone glue was added to the deionized water, slowly stirred for 1 hour, and then 1.0g of potassium hydroxide was added, nitrogen was introduced, heated to 95°C, and slowly stirred until dissolved to obtain a first viscous solution; the second step was to add 20g of chloromethylnaphthalene, 25g of diethylenetriamine and 20g of hydrogen peroxide in sequence to the first viscous solution, nitrogen was slowly introduced into the viscous aqueous solution, and a pH regulator was added to adjust the pH value of the solution to 11, and stirred at 85°C for 5 hours to obtain a mixed solution; the third step was to add 0.8g of neopentyl glycol diacrylate to the mixed solution, and heated to 150°C, stirred until it became viscous to react, and obtain a second viscous solution; the fourth step was to pour out the second viscous solution, dry it, and grind it to obtain a white powdery water-based salt-resistant and calcium-resistant fluid loss reducer for drilling fluid.

[0045] Example 18: The salt-resistant and calcium-resistant fluid loss reducer for water-based drilling fluid was prepared according to the following method: the first step was to add 1L of deionized water into a three-necked flask, and then 40g of bone glue was added to the deionized water, slowly stirred for 1 hour, and then 1.0g of potassium hydroxide was added, nitrogen was introduced, heated to 95°C, and slowly stirred until dissolved to obtain a first viscous solution; the second step was to add 20g of chloromethylnaphthalene, 30g of diethylenetriamine and 20g of hydrogen peroxide in sequence to the first viscous solution, nitrogen was slowly introduced into the viscous aqueous solution, and a pH regulator was added to adjust the pH value of the solution to 11, and stirred at 75°C for 5 hours to obtain a mixed solution; the third step was to add 1.0g of neopentyl glycol diacrylate to the mixed solution, and heated to 150°C, stirred until it became viscous to react, and obtain a second viscous solution; the fourth step was to pour out the second viscous solution, dry it, and grind it to obtain a white powdery water-based salt-resistant and calcium-resistant fluid loss reducer for drilling fluid.

[0046] The following is the indoor evaluation test results of the salt and calcium resistance performance and solubility of the salt and calcium resistance fluid loss reducer for water-based drilling fluid of the present invention.

[0047] Preparation of fresh water base slurry:

[0048] In a sample cup of a high-speed blender, add 350 mL of distilled water, 1.0 g of sodium bicarbonate, 0.28 g of sodium carbonate, and 16 g of bentonite for drilling fluid test preparation. Stir on the blender for 30 minutes. During stirring, scrape off any bentonite adhering to the plastic bucket wall twice. Curing for 24 hours is then performed before use. Six parts of base slurry were prepared according to the methods described in Examples 12 to 18 above. Five parts of the base slurry were added with 1% of the salt- and calcium-resistant fluid loss additive for water-based drilling fluid described in Examples 12 to 18 of the present invention. One part was a blank sample. After stirring on a high-speed blender for 20 minutes, the mixture was tumble-cured at 160°C for 16 hours. High-speed stirring was then repeated for 5 minutes, and the fluid loss was measured, as shown in Table 1.

[0049] Preparation of salt water based slurry:

[0050] In a high-speed blender sample cup, add 350 mL of distilled water, 1.0 g of sodium bicarbonate, 0.28 g of sodium carbonate, 16 g of bentonite for drilling fluid test preparation, 53 g of sodium chloride, and 17.5 g of potassium chloride. Stir on the blender for 30 minutes, scraping any bentonite adhering to the plastic bucket wall twice during stirring. Curing for 24 hours before use. Six parts of base slurry were prepared according to the methods described in Examples 12 to 17 above. Five parts of the base slurry were added with 0.5% of the fluid loss additive described in Examples 12 to 18 of the present invention, respectively. One part was a blank sample. After stirring on the blender for 20 minutes, the mixture was tumble-cured at 160°C for 16 hours. High-speed stirring was then repeated for 5 minutes, and the fluid loss was measured, as shown in Table 1.

[0051] Preparation of calcium-based slurry:

[0052] In a high-speed blender sample cup, add 350 mL of distilled water, 1.0 g of sodium bicarbonate, 0.28 g of sodium carbonate, 16 g of bentonite for drilling fluid test preparation, and 10.5 g of calcium chloride. Stir on the blender for 30 minutes, scraping any bentonite adhering to the plastic bucket walls twice during stirring. Curing for 24 hours before use. Six parts of base slurry were prepared according to the methods described in Examples 12 to 18 above. Five parts of the base slurry were added with 0.5% of the fluid loss additive described in Examples 12 to 18 of the present invention, respectively. One part was a blank sample. After stirring on the blender for 20 minutes, the mixture was tumble-cured at 160°C for 16 hours. High-speed stirring was then repeated for 5 minutes, and the fluid loss was measured, as shown in Table 1.

[0053] According to the data in Table 1, it can be seen that the salt-resistant and calcium-resistant fluid loss reducer for water-based drilling fluid of the present invention has an outstanding fluid loss reduction effect before and after high-temperature aging at 160°C under the condition of 1 part addition, and has good temperature resistance, salt resistance and calcium resistance.

[0054] Prepare two 450 mL beakers, add 300 mL of deionized water to each beaker, add 0.8% of the salt-resistant and calcium-resistant fluid loss reducer for water-based drilling fluid obtained in Examples 12 to 18 of the present invention to each beaker, stir at 350 r / min until completely dissolved, and calculate the time for complete dissolution. The results are shown in Table 2.

[0055] According to the data in Table 2, it can be seen that under the same conditions, all the formulations in Examples 12 to 18 can be completely dissolved, indicating that the salt-resistant and calcium-resistant fluid loss reducer for water-based drilling fluid of the present invention has good hydrophilicity and meets the requirements of on-site preparation of water-based drilling fluid. This is precisely because the addition of chloromethylnaphthalene hydrophilic groups in the raw materials can effectively improve the solubility of the samples.

[0056] In summary, the preparation method of the present invention is simple, the raw materials used are low in cost, the preparation process is simple and easy to obtain, the pollution to the environment is small, and it has good temperature resistance, salt resistance and calcium resistance. It can significantly improve the stability of the well wall during the drilling process, improve the filtration and wall-building properties of the drilling fluid, and has a good filtration loss reduction effect.

[0057] The above technical features constitute the embodiments of the present invention, which have strong adaptability and implementation effect. Non-essential technical features can be added or removed according to actual needs to meet the requirements of different situations.

[0058]

Claims

1. A salt-resistant and calcium-resistant fluid loss reducer for water-based drilling fluid, characterized in that The raw materials include, by weight, 35 to 60 parts of bone glue, 15 to 25 parts of chloromethylnaphthalene, 25 to 40 parts of diethylenetriamine, 0 to 1 part of neopentyl glycol diacrylate, 0.3 to 1 part of potassium hydroxide, and 15 to 30 parts of hydrogen peroxide. The salt-resistant and calcium-resistant fluid loss reducer for water-based drilling fluid is prepared according to the following method: first, deionized water is added to a reaction container, and then the required amount of bone glue is added to the deionized water, and the mixture is slowly stirred for 1 hour, and then potassium hydroxide is added, nitrogen is introduced, and the mixture is heated to 90° C. to 95° C. and slowly stirred until dissolved to obtain a first viscous solution; The second step is to sequentially add the required amounts of chloromethylnaphthalene, diethylenetriamine and hydrogen peroxide to the first viscous solution, slowly introduce nitrogen into the viscous aqueous solution, add a pH adjuster to adjust the pH value of the solution to 9 to 12, and stir at 75° C. to 90° C. for 4 to 6 hours to obtain a mixed solution; the third step is to add the required amount of initiator neopentyl glycol diacrylate to the mixed solution, heat it to 150° C., stir it until it becomes viscous, and react to obtain a second viscous solution; the fourth step is to pour out the second viscous solution, dry it, and grind it to obtain a salt-resistant and calcium-resistant fluid loss reducer for water-based drilling fluid.

2. The salt-resistant and calcium-resistant fluid loss reducer for water-based drilling fluid according to claim 1, characterized in that The raw materials include, by weight, 40 to 55 parts of bone glue, 15 to 20 parts of chloromethylnaphthalene, 30 to 40 parts of diethylenetriamine, 20 to 30 parts of neopentyl glycol diacrylate, 0.5 to 1 part of potassium hydroxide, and 20 to 30 parts of hydrogen peroxide.

3. The salt-resistant and calcium-resistant fluid loss reducer for water-based drilling fluid according to claim 1 or 2, characterized in that The raw materials include, by weight, 50 to 55 parts of bone glue, 15 to 18 parts of chloromethyl naphthalene, 30 to 35 parts of diethylenetriamine, 25 to 30 parts of neopentyl glycol diacrylate, 0.5 to 0.8 parts of potassium hydroxide, and 20 to 25 parts of hydrogen peroxide.

4. The salt-resistant and calcium-resistant fluid loss reducer for water-based drilling fluid according to claim 3, characterized in that In the first step, the ratio of the mass of deionized water to the total mass of raw materials is 3:

1.

5. The salt-resistant and calcium-resistant fluid loss reducer for water-based drilling fluid according to claim 1, 2 or 4, characterized in that In the second step, the added hydrogen peroxide has a mass percentage concentration of 25%, the nitrogen is introduced for 2 to 3 hours, and the added pH regulator is a potassium hydroxide solution with a mass percentage concentration of 45%.

6. The salt-resistant and calcium-resistant fluid loss reducer for water-based drilling fluid according to claim 5, characterized in that In the third step, the reaction time is 4 to 6 hours.

7. The salt-resistant and calcium-resistant fluid loss reducer for water-based drilling fluid according to claim 1, 2, 4 or 6, characterized in that In the fourth step, the second viscous solution is placed in a constant temperature forced air drying oven and dried at 105° C. to 125° C.

8. The salt-resistant and calcium-resistant fluid loss reducer for water-based drilling fluid according to claim 7, characterized in that The stirring speed in the first step, the second step and the third step is 300 r / min to 400 r / min.

9. A method for preparing the salt-resistant and calcium-resistant fluid loss reducer for water-based drilling fluid according to any one of claims 2 to 8, characterized in that The method is as follows: first, adding deionized water into a reaction container, then adding the required amount of bone glue to the deionized water, slowly stirring for 1 hour, then adding potassium hydroxide, passing nitrogen, heating to 90° C. to 95° C., and slowly stirring until dissolved to obtain a first viscous solution; second, adding the required amount of chloromethylnaphthalene, diethylenetriamine and hydrogen peroxide to the first viscous solution in sequence, slowly passing nitrogen into the viscous aqueous solution, adding a pH adjuster to adjust the pH value of the solution to 9 to 12, and stirring at 75° C. to 90° C. for 4 to 6 hours to obtain a mixed solution; third, adding the required amount of initiator neopentyl glycol diacrylate to the mixed solution, heating to 150° C., stirring until it becomes viscous to react, and obtaining a second viscous solution; fourth, pouring out the second viscous solution, drying it, and then grinding it to obtain a salt-resistant and calcium-resistant fluid loss reducer for water-based drilling fluid.

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