Temperature-resistant salt-resistant modified sulfonated phenolic resin for drilling fluid and preparation method of temperature-resistant salt-resistant modified sulfonated phenolic resin

Abstract

The invention belongs to the technical field of oil field drilling, and particularly relates to temperature-resistant and salt-resistant modified sulfonated phenolic resin for drilling fluid and a preparation method thereof.The modified sulfonated phenolic resin is prepared through the steps that phenolic resin is subjected to functionalization modification through a functionalization modification reagent, and a phenolic resin modified material is prepared; the quaternary ammonium cation in the structure of the dual-ion polymeric monomer can be adsorbed on the surfaces of clay particles through electrostatic adsorption, and the clay particles can be tightly coated by a polyoxyethylene ether molecular chain, so that the clay particles can be effectively adsorbed by combining the dual combination effects of electrostatic acting force and Van der Waals force. In addition, due to the existence of sulfonic acid anions, the salt resistance of the resin can be improved, the resin can be promoted to quickly form a coating film on the surface of the clay, and the multiple effects are combined, so that the prepared sulfonated phenolic resin shows excellent temperature-resistant, salt-resistant and filtrate-loss-reducing properties.

Description

Technical Field

[0001] This invention belongs to the field of oilfield drilling technology, specifically relating to a temperature- and salt-resistant modified sulfonated phenolic resin for drilling fluid and its preparation method. Background Technology

[0002] Drilling fluid is a special fluid circulated in drilling operations and is often referred to as the "blood of drilling." Its core functions include cleaning cuttings at the bottom of the well, cooling and lubricating drill strings, balancing formation pressure, stabilizing the wellbore, transmitting hydraulic power, and protecting oil and gas reservoirs. In deep wells, ultra-deep wells, and under complex geological conditions, the performance of drilling fluid directly determines drilling efficiency, safety, and the effectiveness of reservoir protection.

[0003] Phenolic resin, as one of the main filtration loss reducers in drilling fluids, has been widely used in drilling operations since its introduction. It has stable performance and good filtration loss reduction effect, especially in deep wells with high temperature and high pressure, where it plays a crucial role. Sulfonated phenolic resin, which is modified by sulfonation, has a good salt resistance effect. For example, the invention patent with publication number CN116333697B discloses a method for preparing a filtration loss reducer for drilling fluids using modified lignite resin. By sulfonating phenolic resin, the drilling fluid is given better comprehensive performance. However, the existing sulfonated phenolic resin mainly relies on van der Waals forces to adsorb onto the surface of clay particles, which results in a small amount of adsorption on the clay surface. As the downhole temperature increases, it gradually becomes unstable and eventually detaches from the clay surface. Therefore, the existing sulfonated phenolic resin still has defects in practical applications. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the present invention aims to provide a temperature- and salt-resistant modified sulfonated phenolic resin for drilling fluids and its preparation method.

[0005] A first aspect of the present invention provides a temperature- and salt-resistant modified sulfonated phenolic resin for drilling fluids, comprising the following raw materials measured in parts by weight: The mixture contains 65-75 parts of phenolic resin, 10-20 parts of functionalizing modifier, 1-3 parts of catalyst, 15-30 parts of biionic polymerizable monomer, and 0.1-0.2 parts of initiator.

[0006] As a preferred embodiment of the present invention, the functionalizing agent is at least one of acryloyl chloride or methacryloyl chloride.

[0007] As a preferred embodiment of the present invention, the catalyst is at least one of pyridine or triethylamine.

[0008] As a preferred embodiment of the present invention, the method for preparing the dual-ion polymerizable monomer includes the following steps: Step S1: Add allyl polyoxyethylene ether to tetrahydrofuran and stir until a homogeneous reaction solution is formed. Then, add sodium succinic anhydride-3-sulfonate to the reaction solution. After the addition is complete, turn on the heater and control the temperature at 40-50℃. Keep the temperature and stir for 2-6 hours. Then evaporate the solvent, collect the product, and purify it to obtain the intermediate. Step S2: Add the intermediate and acetone to the reactor, start stirring, mix evenly, then purge with nitrogen for protection, and add the composite catalyst to the reactor. After addition, stir and mix at room temperature for 1-2 hours. Then continue to add 2-hydroxy-N,N,N-trimethylethylammonium chloride to the reactor. After addition, stir at 30-40℃ for 4-8 hours, evaporate to remove the solvent, and the product is purified to obtain the biionic polymer monomer.

[0009] As a preferred embodiment of the present invention, the allyl polyoxyethylene ether has a number-average molecular weight of 400.

[0010] As a preferred embodiment of the present invention, the molar ratio of allyl polyoxyethylene ether to sodium succinic anhydride-3-sulfonate is 1:1.

[0011] As a preferred embodiment of the present invention, the composite catalyst is a mixture of dicyclohexylcarbodiimide and 4-dimethylaminopyridine in a mass ratio of 1:0.3-0.4.

[0012] As a preferred embodiment of the present invention, the molar ratio of the intermediate to 2-hydroxy-N,N,N-trimethylethylammonium chloride is 1:1.

[0013] As a preferred embodiment of the present invention, the initiator is at least one of azobisisobutyronitrile or azobisisoheptanenitrile.

[0014] In the above technical solution, allyl polyoxyethylene ether and sodium succinic anhydride-3-sulfonate are first used as raw materials. The active hydroxyl substituents and anhydride groups in their structures can undergo ring-opening esterification reaction to obtain a polyoxyethylene ether derivative containing sulfonic acid groups and active carboxyl substituents, i.e., an intermediate. Then, under the action of a composite catalyst, the active carboxyl group of the intermediate can undergo esterification condensation with the hydroxyl group in the structure of 2-hydroxy-N,N,N-trimethylethylammonium chloride to obtain a polyoxyethylene ether derivative containing both sulfonic acid anions and quaternary ammonium salt cations, i.e., a biionic polymer monomer.

[0015] A method for preparing a temperature- and salt-resistant modified sulfonated phenolic resin for drilling fluids includes the following steps: Step 1: Add phenolic resin to acetone. After addition, mechanically stir to mix evenly. Then, under ice bath conditions, add functionalizing agent and catalyst to the formed mixed solution. After addition, remove from ice bath and stir at 30-40℃ for 2-4 hours. Evaporate to remove solvent and collect product to obtain phenolic resin modified material. The second step involves adding the phenolic resin modifier and xylene to the polymerization reactor, purging with nitrogen for protection, then adding the biionic polymerization monomer and initiator to the polymerization reactor, turning on the heater, raising the temperature to 70-90℃, maintaining the temperature for 12-16 hours, stopping the heating, separating the product, and purifying it to obtain the modified sulfonated phenolic resin.

[0016] In the above technical solution, firstly, a functionalizing agent is used to functionalize the phenolic resin to obtain a phenolic resin containing unsaturated alkenyl functional groups in its structure, namely, a modified phenolic resin. Then, under the action of an initiator, the unsaturated alkenyl functional groups in the structure of the biionic polymerizable monomer undergo a free radical polymerization reaction with the unsaturated alkenyl groups in the modified phenolic resin to obtain a modified sulfonated phenolic resin.

[0017] Compared with the prior art, the present invention has the following beneficial effects: This invention prepares a modified sulfonated phenolic resin by in-situ polymerization of a biionic monomer with phenolic resin. On one hand, the presence of quaternary ammonium cations increases the resin concentration around negatively charged clay particles through electrostatic adsorption, allowing the resin to be adsorbed onto the clay particle surface. Simultaneously, the polyoxyethylene ether molecular chains in the resin structure possess strong hydrophilicity, enabling tight coating of the highly hydrophilic clay particles. This, combined with the dual binding effects of electrostatic and van der Waals forces, firmly encapsulates the clay particle surface. On the other hand, the sulfonic acid anions in the resin structure can complex with metal salt ions, thus giving the resin excellent salt resistance. Furthermore, the presence of sulfonic acid anions promotes rapid formation of a coating film on the clay surface, reducing flocculation and improving the stability of colloids and slurry. The combination of these multiple effects effectively prevents water from contacting the clay particles, maintaining a reasonable particle size distribution and forming a dense mud cake, exhibiting excellent resistance to temperature and salt, and reduced filtration loss. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1This is an infrared analysis test image of a monomer that undergoes biionic polymerization. Detailed Implementation

[0020] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0021] The sources of some components in the examples and comparative examples are as follows: Example 1 This embodiment provides a temperature- and salt-resistant modified sulfonated phenolic resin for drilling fluids, which is made from the following raw materials measured in parts by weight: 65 parts phenolic resin, 10 parts methacryloyl chloride, 1 part pyridine, 15 parts biionic polymerizable monomer, and 0.1 parts azobisisobutyronitrile.

[0022] The preparation method of the modified sulfonated phenolic resin includes the following steps: Step 1: Add phenolic resin to acetone. After addition, mechanically stir to mix evenly. Then, under ice bath conditions, add methacryloyl chloride and pyridine to the resulting mixture. After addition, remove from the ice bath and stir at 35°C for 3 hours. Evaporate to remove the solvent and collect the product to obtain the modified phenolic resin. The second step involves adding the phenolic resin modifier and xylene to the polymerization reactor, purging with nitrogen for protection, and then adding the biionic monomer and azobisisobutyronitrile to the polymerization reactor. Heating is then started, and the temperature is raised to 80°C. After maintaining the temperature for 16 hours, heating is stopped, the product is separated, and purified to obtain the modified sulfonated phenolic resin.

[0023] The biionic monomers were prepared using the following method: Step S1: Add 1.2g of allyl polyoxyethylene ether with a number average molecular weight of 400 to tetrahydrofuran and stir until a homogeneous reaction solution is formed. Then, add 0.6g of sodium succinic anhydride-3-sulfonate to the reaction solution. After the addition is complete, turn on the heater and control the temperature at 45°C. After stirring for 4 hours, evaporate the solvent, collect the product, and purify it to obtain the intermediate. Step S2: Add 0.9g of intermediate and acetone to the reactor, start stirring, mix evenly, then purge with nitrogen for protection. Add 0.1g of dicyclohexylcarbodiimide and 0.04g of 4-dimethylaminopyridine to the reactor. After addition, stir and mix at room temperature for 1 hour. Then add 0.2g of 2-hydroxy-N,N,N-trimethylethylammonium chloride to the reactor. After addition, stir at 35°C for 6 hours. Evaporate to remove the solvent. After purification, the product can be purified to obtain the biionic monomer.

[0024] Figure 1This is the infrared analysis result of the biionic monomer, where 3340 cm⁻¹... -1 The characteristic absorption peak appearing at 3095 cm⁻¹ is attributed to the characteristic OH absorption peak of the sulfonic acid group. -1 The characteristic absorption peak appearing at 1751 cm⁻¹ is attributed to the CH characteristic absorption peak of the unsaturated alkenyl functional group. -1 The characteristic absorption peak appearing at 1081 cm⁻¹ is attributed to the C=O characteristic absorption peak of the ester group. -1 The characteristic absorption peak appearing at this point is attributed to the CO characteristic absorption peak of the ether bond.

[0025] Example 2 This embodiment provides a temperature- and salt-resistant modified sulfonated phenolic resin for drilling fluids, which is made from the following raw materials measured in parts by weight: 70 parts phenolic resin, 15 parts methacryloyl chloride, 2 parts pyridine, 25 parts biionic monomer, and 0.2 parts azobisisobutyronitrile.

[0026] The preparation method of the modified sulfonated phenolic resin includes the following steps: Step 1: Add phenolic resin to acetone. After addition, mechanically stir to mix evenly. Then, under ice bath conditions, add methacryloyl chloride and pyridine to the resulting mixture. After addition, remove from the ice bath and stir at 35°C for 3 hours. Evaporate to remove the solvent and collect the product to obtain the modified phenolic resin. The second step involves adding the phenolic resin modifier and xylene to the polymerization reactor, purging with nitrogen for protection, and then adding the biionic monomer and azobisisobutyronitrile to the polymerization reactor. Heating is then started, and the temperature is raised to 80°C. After maintaining the temperature for 16 hours, heating is stopped, the product is separated, and purified to obtain the modified sulfonated phenolic resin.

[0027] The preparation method of the biionic polymer monomer is described in Example 1.

[0028] Example 3 This embodiment provides a temperature- and salt-resistant modified sulfonated phenolic resin for drilling fluids, which is made from the following raw materials measured in parts by weight: 75 parts phenolic resin, 20 parts methacryloyl chloride, 3 parts pyridine, 30 parts biionic monomer, and 0.2 parts azobisisobutyronitrile.

[0029] The preparation method of the modified sulfonated phenolic resin includes the following steps: Step 1: Add phenolic resin to acetone. After addition, mechanically stir to mix evenly. Then, under ice bath conditions, add methacryloyl chloride and pyridine to the resulting mixture. After addition, remove from the ice bath and stir at 35°C for 3 hours. Evaporate to remove the solvent and collect the product to obtain the modified phenolic resin. The second step involves adding the phenolic resin modifier and xylene to the polymerization reactor, purging with nitrogen for protection, and then adding the biionic monomer and azobisisobutyronitrile to the polymerization reactor. Heating is then started, and the temperature is raised to 80°C. After maintaining the temperature for 16 hours, heating is stopped, the product is separated, and purified to obtain the modified sulfonated phenolic resin.

[0030] The preparation method of the biionic polymer monomer is described in Example 1.

[0031] Comparative Example 1 The difference between this comparative example and Example 2 is that the biionic polymerized monomer intermediate is replaced with an intermediate, while the rest are the same.

[0032] The preparation method of the intermediate is described in Example 1.

[0033] The modified sulfonated phenolic resins provided in the above embodiments and comparative examples were subjected to performance tests, and the test methods are as follows: Add 0.5g of anhydrous sodium carbonate and 6.8g of bentonite to 350mL of deionized water, stir mechanically, and cure at 25℃ for one day. Then add 10g of sulfonated lignite and 10.5g of the above-mentioned modified sulfonated phenolic resin, stir mechanically, add 110g of sodium chloride, stir until completely dissolved, cure at 25℃ for 3 hours, and then heat-roll at 220℃ for 16 hours. Remove and allow to cool completely naturally. Add 6g of anhydrous sodium carbonate, stir and mix well to prepare a high-salt drilling fluid sample for testing. According to standard GB / T 16783.1-2014, the filtration loss was tested under test conditions of 25℃, 0.7MPa and 180℃, 3.5MPa, respectively, and recorded as filtration loss at normal temperature and pressure and filtration loss at high temperature and pressure. The performance test data above are shown in Table 1: Table 1 - Performance Test Results

[0034] The commercially available sulfonated phenolic resin is the SMP-II type sulfonated phenolic resin.

[0035] As can be seen from the above, the modified sulfonated phenolic resin prepared in the embodiments of the present invention exhibits excellent filtration loss reduction performance in high-salt solutions, and also demonstrates relatively good high-temperature resistance. After replacing the biionic polymerization monomer intermediate with another intermediate, the prepared modified sulfonated phenolic resin structure does not contain quaternary ammonium cations, resulting in relatively poor adsorption of clay particles. Consequently, the filtration loss reduction performance is severely reduced, and the filter cake stability is also affected, leading to a simultaneous impact on high-temperature resistance.

[0036] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention, including the best mode, and also to enable any person skilled in the art to practice the present invention, including manufacturing and using any device or system, and implementing any combined method. It should be noted that for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the present invention.

Claims

1. A temperature- and salt-resistant modified sulfonated phenolic resin for drilling fluids, characterized in that, It is made from the following raw materials, measured in parts by weight: The composition includes 65-75 parts phenolic resin, 10-20 parts functionalizing modifier, 1-3 parts catalyst, 15-30 parts biionic polymerization monomer, and 0.1-0.2 parts initiator. The functionalizing agent is at least one of acryloyl chloride or methacryloyl chloride; The catalyst is at least one of pyridine or triethylamine; The preparation method of the dual-ion polymerizable monomer includes the following steps: Step S1: Add allyl polyoxyethylene ether to tetrahydrofuran and stir until a homogeneous reaction solution is formed. Then, add sodium succinic anhydride-3-sulfonate to the reaction solution. After the addition is complete, turn on the heater and control the temperature at 40-50℃. Keep the temperature and stir for 2-6 hours. Then evaporate the solvent, collect the product, and purify it to obtain the intermediate. Step S2: Add the intermediate and acetone to the reactor, start stirring, mix evenly, then purge with nitrogen for protection, and add the composite catalyst to the reactor. After addition, stir and mix at room temperature for 1-2 hours. Then continue to add 2-hydroxy-N,N,N-trimethylethylammonium chloride to the reactor. After addition, stir at 30-40℃ for 4-8 hours, evaporate to remove the solvent, and the product is purified to obtain the biionic polymer monomer. The initiator is at least one of azobisisobutyronitrile or azobisisoheptanenitrile.

2. The temperature- and salt-resistant modified sulfonated phenolic resin for drilling fluid according to claim 1, characterized in that, The number average molecular weight of the allyl polyoxyethylene ether is 400.

3. The temperature- and salt-resistant modified sulfonated phenolic resin for drilling fluid according to claim 1, characterized in that, The molar ratio of the allyl polyoxyethylene ether to sodium succinic anhydride-3-sulfonate is 1:

1.

4. The temperature- and salt-resistant modified sulfonated phenolic resin for drilling fluid according to claim 1, characterized in that, The composite catalyst is a mixture of dicyclohexylcarbodiimide and 4-dimethylaminopyridine in a mass ratio of 1:0.3-0.

4.

5. The temperature- and salt-resistant modified sulfonated phenolic resin for drilling fluid according to claim 1, characterized in that, The molar ratio of the intermediate to 2-hydroxy-N,N,N-trimethylethylammonium chloride is 1:

1.

6. A method for preparing the temperature- and salt-resistant modified sulfonated phenolic resin for drilling fluid as described in claim 1, characterized in that, Includes the following steps: Step 1: Add phenolic resin to acetone. After addition, mechanically stir to mix evenly. Then, under ice bath conditions, add functionalizing agent and catalyst to the formed mixed solution. After addition, remove from ice bath and stir at 30-40℃ for 2-4 hours. Evaporate to remove solvent and collect product to obtain phenolic resin modified material. The second step involves adding the phenolic resin modifier and xylene to the polymerization reactor, purging with nitrogen for protection, then adding the biionic polymerization monomer and initiator to the polymerization reactor, turning on the heater, raising the temperature to 70-90℃, maintaining the temperature for 12-16 hours, stopping the heating, separating the product, and purifying it to obtain the modified sulfonated phenolic resin.

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