A temperature-resistant and salt-resistant filtrate reducer based on phenolic resin and a preparation method thereof

Abstract

The application discloses a temperature-resistant and salt-resistant filtrate reducer based on phenolic resin and a preparation method thereof, and comprises the following steps: S1, under the condition of an acid catalyst, linear phenolic resin is synthesized by polycondensation with phenol and formaldehyde as raw materials; S2, the linear phenolic resin is subjected to etherification reaction with a bromoalkyl nitrile under the condition of alkalinity; and S3, the phenolic resin after etherification is hydrolyzed into amide phenolic resin under the condition of alkalinity. The drilling fluid additive prepared by the application combines the high-temperature resistance of the phenolic resin and the excellent adsorption and filtrate reduction capacity of the polyacrylamide, solves the problem that the existing phenolic resin needs to be used in combination in the drilling fluid, and simultaneously has excellent effects of high-temperature resistance, salt resistance and filtrate reduction.

Description

Technical Field

[0001] This invention relates to the field of filtration loss reducing agents, and in particular to a temperature- and salt-resistant filtration loss reducing agent based on phenolic resin and its preparation method. Background Technology

[0002] With the continuous development of shallow and simple formations, oil exploration and development are moving towards deeper and more complex formations. Oil drilling environments are becoming increasingly complex, often accompanied by high temperature, high pressure, and high mineralization. Fluid loss control agents effectively control drilling fluid loss, ensuring safe and efficient oil drilling. They are the most widely used and invested drilling fluid treatment agents in the oil drilling process.

[0003] Polyacrylamide is a water-soluble polymer synthesized from acrylamide monomers. Its main chain consists of carbon-carbon bonds, and its side chains are amide groups. As a filtration reducer, polyacrylamide's amide groups adsorb onto the surface of wellbore rock and drill cuttings through hydrogen bonding and electrostatic interactions, forming a dense, low-permeability flexible film that effectively seals micro-cracks and pores. However, when the bottom-hole temperature exceeds 120°C, polyacrylamide undergoes high-temperature degradation, significantly reducing its effectiveness. Phenolic resin, a high-temperature resistant resin, can be used in high-temperature drilling fluids through sulfonation. However, compared to polyacrylamide, sulfonated phenolic resin lacks amide groups capable of adsorbing clay in its molecular structure, and its phenolic hydroxyl and sulfonyl groups have weaker filtration-reducing effects. It mainly relies on its temperature and salt resistance properties, while its sealing and film-forming abilities require supplementation with other treatment agents. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a temperature- and salt-resistant filtration loss reducing agent based on phenolic resin and its preparation method, so as to solve the problems of weak blocking and film-forming ability and poor filtration loss reduction effect caused by the absence of side-chain amide groups in existing phenolic resins.

[0005] The objective of this invention is achieved through the following technical solution: a method for preparing a temperature- and salt-resistant filtration loss reducing agent based on phenolic resin, comprising the following steps, S1. A linear phenolic resin is synthesized by condensation polymerization of phenol and formaldehyde under acidic catalytic conditions. S2. Linear phenolic resin undergoes an etherification reaction with brominated alkyl nitrile under alkaline conditions; S3. The etherified phenolic resin is hydrolyzed into amidated phenolic resin under alkaline conditions.

[0006] Preferably, the bromoalkyl nitrile is one of 4-bromobutyronitrile or bromoacetonitrile.

[0007] Preferably, in step S1, phenol is added to a container and heated to melt it, an acidic catalyst is added, formaldehyde aqueous solution is slowly added dropwise, the temperature is raised to 90-95°C, and the reaction is stirred for 4-6 hours.

[0008] Preferably, in step S1, the molar ratio of phenol to formaldehyde is 1:(0.75-0.85).

[0009] Preferably, in step S2, linear phenolic resin is added to DMF solvent, heated until completely dissolved, anhydrous potassium carbonate is added, bromoalkyl nitrile is added dropwise, and the mixture is heated to 60-80°C and stirred for 12-15 hours.

[0010] Preferably, the molar ratio of phenolic hydroxyl groups to brominated alkyl nitrile to potassium carbonate in the linear phenolic resin is 1:(1.1-1.2):(1.5-2.0).

[0011] Preferably, in step S3, the etherified phenolic resin is dissolved in DMSO solvent, potassium carbonate is added and stirred evenly, the temperature is controlled at 0-5℃, hydrogen peroxide is slowly added dropwise, and after the addition is completed, the temperature is raised to room temperature and stirred for 2 hours.

[0012] Preferably, the molar ratio of nitrile groups in the etherified resin to potassium carbonate to hydrogen peroxide is 1:(0.5-1):(2-3).

[0013] The present invention has the following advantages: 1. This invention provides a modified petroleum drilling additive based on phenolic resin. By replacing the hydroxyl groups retained on the linear phenolic resin with nitrile groups through etherification, and then hydrolyzing the nitrile groups into amide groups by precisely controlling the hydrolysis conditions, the primary amide is successfully grafted onto the benzene ring. The resulting unique structure eliminates the high-temperature resistance of existing polyacrylamide and grafts the strong hydrogen bonding and electrostatic interaction capabilities of polyacrylamide onto the high-temperature resistant but weak filtration loss reduction effect of phenolic resin. This results in a modified phenolic resin that simultaneously possesses the functions of high temperature resistance, salt resistance, and strong filtration loss reduction effect, solving the problem that existing sulfonated phenolic resins need to be compounded with other components in drilling fluids to seal well wall cracks. 2. The method for preparing amide-modified phenolic resin according to the present invention only requires two steps: etherification and hydrolysis. The preparation and synthesis process is short, the reaction conditions are easy to control, and it is suitable for mass production. Detailed Implementation

[0014] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below.

[0015] A phenolic resin-based agent for reducing filtration loss under temperature and salt conditions is prepared according to the following steps. S1. Under acidic catalytic conditions, phenol and formaldehyde are used as raw materials to undergo condensation polymerization to form linear phenolic resin. The amount of formaldehyde is strictly controlled during the synthesis process to maintain the linear structure of the phenolic resin. S2. Linear phenolic resin undergoes an etherification reaction with brominated alkyl nitrile under alkaline conditions. In this reaction, the phenolic hydroxyl group is deprotonated under weakly alkaline conditions to form a phenoxy anion (a strong nucleophile). The phenoxy anion attacks the α-carbon of the primary brominated alkane via an SN2 mechanism, and the bromine atom leaves to form an aryl alkyl ether bond. The nitrile group is then branched onto the benzene ring through the ether bond. S3. The etherified phenolic resin hydrolyzes into amidated phenolic resin under alkaline conditions, and hydrogen peroxide generates hydrogen peroxide anions (HOO) under alkaline conditions. - The peroxyhydrogen anion nucleophilically attacks the carbon atom in the cyano group (-C≡N), generating a peroxyimino acid intermediate. The generated peroxyimino acid is a strong oxidizing agent, which reacts with the added dimethyl sulfoxide (DMSO) as a reducing agent and oxygen acceptor, rapidly consuming the intermediate. DMSO takes the oxygen from the peroxyimino acid and is itself oxidized to dimethyl sulfoxide. At the same time, the cyano group is converted into a primary amide, successfully converting the nitrile group grafted on the benzene ring into an amide group. Example 1

[0016] A phenolic resin-based filtration loss reducing agent with temperature and salt resistance is prepared according to the following steps. S1. Add 47g of phenol to a reaction vessel and heat to 60℃ to melt it. Add 1.5% oxalic acid by mass of phenol as an acidic catalyst. Slowly add 35g of 37% formaldehyde aqueous solution. Slowly raise the temperature to 90℃ and stir the reaction for 5h. Then distill off the water and phenol under reduced pressure to obtain a brittle solid linear phenolic resin. S2. Add 10g of linear phenolic resin to 80ml of DMF solvent, heat to 40℃ and dissolve completely, add 22.1g of anhydrous potassium carbonate, add 13g of bromoalkyl nitrile dropwise over 20min, heat to 60℃ and stir for 15h. The reaction is protected by nitrogen throughout, concentrated under reduced pressure, neutralized with hydrochloric acid, extracted multiple times and combined organic phases, dried with anhydrous sodium sulfate, and the solvent is evaporated to obtain etherified phenolic resin. S3. Dissolve 10g of etherified phenolic resin in 50ml of DMSO solvent, add 2.1g of potassium carbonate and stir until homogeneous. Control the temperature to 0-5℃, slowly add 8.5ml of 30% hydrogen peroxide dropwise. After the addition is complete, raise the temperature to room temperature and stir for 2h. Add 10% sodium thiosulfate solution for quenching, adjust the pH to neutral, extract and combine the organic phases, dry the organic phase with anhydrous sodium sulfate, and evaporate to remove the solvent to obtain amidated phenolic resin. Example 2

[0017] A phenolic resin-based filtration loss reducing agent with temperature and salt resistance is prepared according to the following steps. S1. Add 47g of phenol to a reaction vessel and heat to 60℃ to melt it. Add 1.5% oxalic acid by mass of phenol as an acidic catalyst. Slowly add 30.8g of 37% formaldehyde aqueous solution. Slowly raise the temperature to 95℃ and stir the reaction for 6h. Then distill off the water and phenol under reduced pressure to obtain a brittle solid linear phenolic resin. S2. Add 10g of linear phenolic resin to 80ml of DMF solvent, heat to 40℃ and dissolve completely, add 16.6g of anhydrous potassium carbonate, add 14.2g of bromoalkyl nitrile dropwise over 20min, heat to 80℃ and stir for 12h. The reaction is protected by nitrogen gas throughout, concentrated under reduced pressure, neutralized with hydrochloric acid, extracted multiple times and combined organic phases, dried with anhydrous sodium sulfate, and the solvent is evaporated to obtain etherified phenolic resin. S3. Dissolve 10g of etherified phenolic resin in 50ml of DMSO solvent, add 4.2g of potassium carbonate and stir until homogeneous. Control the temperature to 0-5℃, slowly add 5.7ml of 30% hydrogen peroxide dropwise. After the addition is complete, raise the temperature to room temperature and stir for 2h. Add 10% sodium thiosulfate solution for quenching, adjust the pH to neutral, extract and combine the organic phases, dry the organic phase with anhydrous sodium sulfate, and evaporate to remove the solvent to obtain amidated phenolic resin. Example 3

[0018] A phenolic resin-based filtration loss reducing agent with temperature and salt resistance is prepared according to the following steps. S1. Add 47g of phenol to a reaction vessel and heat to 60℃ to melt it. Add 1.5% oxalic acid by mass of phenol as an acidic catalyst. Slowly add 30.8g of 37% formaldehyde aqueous solution. Slowly raise the temperature to 95℃ and stir the reaction for 4h. Then distill off the water and phenol under reduced pressure to obtain a brittle solid linear phenolic resin. S2. Add 10g of linear phenolic resin to 80ml of DMF solvent, heat to 40℃ and dissolve completely, add 16.6g of anhydrous potassium carbonate, add 14.2g of bromoalkyl nitrile dropwise over 20min, heat to 80℃ and stir for 12h. The reaction is protected by nitrogen gas throughout, concentrated under reduced pressure, neutralized with hydrochloric acid, extracted multiple times and combined organic phases, dried with anhydrous sodium sulfate, and the solvent is evaporated to obtain etherified phenolic resin. S3. Dissolve 10g of etherified phenolic resin in 50ml of DMSO solvent, add 2.1g of potassium carbonate and stir until homogeneous. Control the temperature to 0-5℃, slowly add 8.5ml of 30% hydrogen peroxide dropwise. After the addition is complete, raise the temperature to room temperature and stir for 2h. Add 10% sodium thiosulfate solution for quenching, adjust the pH to neutral, extract and combine the organic phases, dry the organic phase with anhydrous sodium sulfate, and evaporate to remove the solvent to obtain amidated phenolic resin.

[0019] Comparative Example A sulfonated phenolic resin is prepared according to the following steps: 47g of phenol and 37ml of 37% formaldehyde are added sequentially to a reaction vessel equipped with a stirrer and a reflux cooler. The mixture is stirred at 120°C for 10 minutes, then cooled and kept at 110°C. Next, 37ml of 37% formaldehyde, 47.5g of sodium metabisulfite, and 40ml of water are added sequentially. The sulfonation time is 3 hours. Finally, 37ml of 37% formaldehyde is added, and the mixture is refluxed at 100°C for 3-4 hours. The resin is then evaporated and dried to obtain the final product.

[0020] Performance Evaluation Base slurry: 4.5 parts by weight of bentonite, 0.5 parts by weight of soda ash, and 100 parts by weight of water. 2% of the products prepared in Examples 1-3 and Comparative Example 1 of this invention were added to the above base slurry and stirred until homogeneous. The static filtration loss and high-temperature high-pressure filtration loss of the test slurry were determined according to GB / T 16783.1-2014 standard under test conditions of 25℃, 0.7MPa and 180℃, 3.5MPa, respectively.

[0021] As shown in the table above, the amide-modified phenolic resin prepared by this invention has excellent resistance to high-temperature filtration loss. Compared with sulfonated modified phenolic resin, it is demonstrated that the large number of amide groups grafted onto the main chain of phenolic resin is more conducive to the main chain adsorbing onto clay particles in drilling fluid and the surface of wellbore rock through hydrogen bonding and electrostatic interaction, thereby improving the filtration loss reduction capacity.

[0022] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a temperature and salt resistant phenol-formaldehyde resin based fluid loss additive, characterized in that, Includes the following steps, S1. A linear phenolic resin is synthesized by condensation polymerization of phenol and formaldehyde under acidic catalytic conditions. S2. Linear phenolic resin undergoes an etherification reaction with brominated alkyl nitrile under alkaline conditions; S3. The etherified phenolic resin is hydrolyzed into amidated phenolic resin under alkaline conditions.

2. The method for preparing a temperature and salt resistant phenolic resin based fluid loss additive according to claim 1, characterized in that, The bromoalkyl nitrile is one of 4-bromobutyronitrile or bromoacetonitrile.

3. The method for preparing a temperature and salt resistant phenolic resin based fluid loss additive according to claim 1, characterized in that, In step S1, phenol is added to a container and heated to melt it. An acidic catalyst is added, and an aqueous formaldehyde solution is slowly added dropwise. The temperature is raised to 90-95°C, and the reaction is stirred for 4-6 hours.

4. The method for preparing a temperature and salt resistant phenolic resin based fluid loss additive according to claim 1, characterized in that, In step S1, the molar ratio of phenol to formaldehyde is 1:(0.75-0.85).

5. The method for preparing a temperature and salt resistant phenolic resin based fluid loss additive according to claim 1, characterized in that, In step S2, linear phenolic resin is added to DMF solvent, heated until completely dissolved, anhydrous potassium carbonate is added, bromoalkyl nitrile is added dropwise, and the mixture is heated to 60-80℃ and stirred for 12-15 hours.

6. The method for preparing a temperature and salt resistant phenolic resin based fluid loss additive according to claim 5, characterized in that, The molar ratio of phenolic hydroxyl groups to brominated alkyl nitrile to potassium carbonate in the linear phenolic resin is 1:(1.1-1.2):(1.5-2.0).

7. The method for preparing a temperature and salt resistant phenolic resin based fluid loss additive according to claim 1, characterized in that, In step S3, the etherified phenolic resin is dissolved in DMSO solvent, potassium carbonate is added and stirred evenly, the temperature is controlled at 0-5℃, hydrogen peroxide is slowly added dropwise, and after the addition is completed, the temperature is raised to room temperature and stirred for 2 hours.

8. The method for preparing a temperature and salt resistant phenol-formaldehyde resin based fluid loss additive according to claim 7, characterized in that, The molar ratio of nitrile groups in the etherified resin to potassium carbonate to hydrogen peroxide is 1:(0.5-1):(2-3).

9. A temperature and salt resistant phenol-formaldehyde resin based fluid loss additive characterized in that, Prepared based on the method described in any one of claims 1-8.

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