Cationic modified enzymatic hydrolysis lignin-based fluid loss additive, and preparation method and application thereof

Abstract

The application belongs to the field of oil and gas exploration and development oil field chemistry and drilling fluid technology, discloses a kind of cation modified enzymatic hydrolysis lignin type fluid loss additive and its preparation method and application.The preparation method includes the following steps: enzymatic hydrolysis lignin, formaldehyde, acid and cation monomer are mixed in water, reaction is carried out, and cation modified enzymatic hydrolysis lignin type fluid loss additive is obtained;The cation monomer is 3-acryloyloxy-2-hydroxypropyl trimethyl ammonium halide;The mass ratio of enzymatic hydrolysis lignin and cation monomer is 10-40:0.3-3.The fluid loss additive provided by the application has excellent temperature resistance and calcium resistance, and can better meet the needs of the field.The preparation method is simple, in line with the modern "green" chemical concept of raw material-production-product whole process green environmental protection, can help the progress of environmental protection type anti-pollution drilling fluid technology, economic and social benefits are remarkable, and has important application value.

Description

Technical Field

[0001] This invention belongs to the field of oilfield chemistry and drilling fluid technology in oil and gas exploration and development, and relates to a cationic modified enzymatic hydrolysis lignin-based filtration loss reducer, its preparation method and application. Background Technology

[0002] In recent years, oil and gas resource development and exploration targets have been rapidly expanding towards deep and complex formations with high mineralization. The encounter with calcium-bearing formations is increasing, and the high-temperature effect of salt-calcium bonding can easily lead to rapid deterioration of drilling fluid system performance, sometimes resulting in sharp thickening and loss of fluidity, thus affecting downhole safety. Besides large-scale replacement with fresh drilling fluid, existing technologies cannot effectively solve the problem of calcium ion contamination. Therefore, higher requirements and challenges are placed on the temperature resistance and salt-calcium resistance of drilling fluids.

[0003] Filtration reducers, as one of the core key treatment agents for high-temperature drilling fluids, play a crucial role in wellbore stability and reservoir protection. Their temperature and calcium resistance properties are essential for the performance and safe drilling of drilling fluids in high-temperature and high-calcium formations. Sulfonated methyl phenolic resin filtration reducer (SMP) is produced by sulfonation and polycondensation of phenol, formaldehyde, and a sulfonating agent. Currently, it is the most widely used and effective high-temperature filtration reducer. While SMP generally has a temperature resistance greater than 150℃, its calcium resistance is less than 1000 mg / L, posing a technical challenge in addressing on-site calcium contamination. Therefore, there is an urgent need to develop new temperature- and calcium-resistant filtration reducers. Summary of the Invention

[0004] To address the problems of the prior art, the present invention aims to provide a cationic modified enzymatic hydrolysis lignin-based filtration loss reducer, its preparation method, and its application. The filtration loss reducer provided by the present invention has excellent temperature and calcium resistance properties, and can better meet the needs of the field.

[0005] One object of the present invention is to provide a method for preparing a cationic modified enzymatic hydrolysis lignin-based filtration loss reducing agent, comprising the following steps:

[0006] Enzymatically hydrolyzed lignin, formaldehyde, acid, and cationic monomers are mixed in water and reacted to obtain a cationic modified enzymatically hydrolyzed lignin-based filtration loss reducer.

[0007] The cationic monomer is 3-acryloyloxy-2-hydroxypropyltrimethylammonium halide; the mass ratio of the enzymatically hydrolyzed lignin to the cationic monomer is 10-40:0.3-3.

[0008] In an embodiment of the present invention, the preparation method includes:

[0009] Step S1: Dissolve enzymatically hydrolyzed lignin in an aqueous formaldehyde solution and carry out a polymerization reaction in the presence of acid to obtain an intermediate solution;

[0010] Step S2: Mix the intermediate solution and the cationic monomer and react to obtain a cationic modified enzymatic hydrolysis lignin-based filtration loss reducer.

[0011] In an embodiment of the present invention, in step S1, the acid is a hydrochloric acid solution with a mass concentration of 30-40%; the mass ratio of the enzymatically hydrolyzed lignin to the hydrochloric acid solution is 10-40:0.1-0.5.

[0012] In an embodiment of the present invention, in step S1, the polymerization reaction is carried out at a temperature of 85–95°C for 3–4 hours.

[0013] In an embodiment of the present invention, in step S2, the reaction temperature is 98–102°C and the time is 2–3 hours.

[0014] In an embodiment of the present invention, after step S2, the reaction further includes: cooling the obtained reaction product to room temperature and spray drying it to obtain a powdered cationic modified enzymatic hydrolysed lignin-based filtration loss reducer.

[0015] In an embodiment of the present invention, the inlet temperature of the spray dryer is 200-205°C and the outlet temperature is 110-115°C.

[0016] Another objective of this invention is to provide a cationic modified enzymatic hydrolysis lignin-based filtration reducer prepared by the method described above, which exhibits good filtration reduction effect in drilling fluids under high calcium ion conditions.

[0017] In addition, the present invention also provides the application of the cationic modified enzymatic hydrolysis lignin-based filtration loss reducer as described above in drilling fluids.

[0018] In an embodiment of the present invention, the calcium ion concentration in the drilling fluid is below 10,000 mg / L.

[0019] Compared with existing technologies, this invention provides a cationic modified enzymatic hydrolyzed lignin-based filtration loss reducer. The technical solution provided by this invention uses enzymatically hydrolyzed lignin, formaldehyde, acid, and the cationic monomer 3-acryloyloxy-2-hydroxypropyltrimethylammonium halide. Through polymerization and other reactions, 3-acryloyloxy-2-hydroxypropyltrimethylammonium halide is grafted onto the enzymatically hydrolyzed lignin to synthesize a cationic monomer-modified enzymatically hydrolyzed lignin-type calcium-resistant filtration loss reducer. This filtration loss reducer possesses multiple adsorption sites, including nitrogen, and can provide lone pairs of electrons to form coordinate bonds with calcium ions, allowing the filtration loss reducer molecules to better adsorb onto the clay surface. This synergistic effect with hydroxyl hydration groups reduces filtration loss and improves the calcium resistance of the filtration loss reducer, achieving a calcium resistance of up to 10000 mg / L. Simultaneously, it maintains good temperature resistance. The modified enzymatically hydrolyzed lignin-based filtration loss reducer described in this invention has good compatibility with various water-based drilling fluids and is easy to use.

[0020] The cationic modified enzymatic hydrolyzed lignin filtration loss reducer provided by this invention uses enzymatically hydrolyzed lignin as raw material. The synthesis time is short, the synthesis temperature is appropriate, the preparation method is simple, and no waste is generated. The synthesized product has excellent anti-calcium and other properties, which is conducive to meeting on-site needs. It conforms to the modern "green" chemical concept of green and environmentally friendly production and product throughout the entire process. It can promote the advancement of environmentally friendly and pollution-resistant drilling fluid technology, and has significant economic and social benefits, and has important application value. Attached Figure Description

[0021] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0022] Figure 1 The Fourier transform infrared absorption spectrum of the modified enzymatic hydrolysis lignin-based filtration loss reducer in Example 5 of this invention;

[0023] Figure 2 This is a SEM image of the modified enzymatic hydrolysis lignin-based filtration loss reducer prepared in Example 5 of the present invention forming a mud cake in drilling fluid. Detailed Implementation

[0024] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] This invention provides a method for preparing a cationic modified enzymatic hydrolyzed lignin-based filtration loss reducer, comprising the following steps: mixing enzymatically hydrolyzed lignin, formaldehyde, acid, and a cationic monomer in water and reacting them to obtain a cationic modified enzymatically hydrolyzed lignin-based filtration loss reducer; wherein the cationic monomer is 3-acryloyloxy-2-hydroxypropyltrimethylammonium halide; and the mass ratio of the enzymatically hydrolyzed lignin to the cationic monomer is 10-40:0.3-3.

[0026] The filtration loss reducer provided by this invention has excellent temperature and calcium resistance properties, which can better meet on-site requirements.

[0027] The technical solution for preparing the filtration loss reducing agent in this invention includes the following raw materials: enzymatically hydrolyzed lignin, formaldehyde (generally an aqueous solution with a mass concentration of, for example, 37%), hydrochloric acid (generally an aqueous solution with a mass concentration of, for example, 36%), and the cationic monomer 3-acryloyloxy-2-hydroxypropyltrimethylammonium chloride. The mass ratio of the enzymatically hydrolyzed lignin to the cationic monomer is 10–40:0.3–3; furthermore, the preferred mass ratio of the enzymatically hydrolyzed lignin, formaldehyde (37%), hydrochloric acid (36%), and the cationic monomer 3-acryloyloxy-2-hydroxypropyltrimethylammonium chloride is (10–40):(20–60):(0.1–0.5):(0.3–3). Most preferably, the mass ratio of the enzymatically hydrolyzed lignin, formaldehyde (37%), hydrochloric acid (36%), and the cationic monomer 3-acryloyloxy-2-hydroxypropyltrimethylammonium chloride is 30:57:0.35:2.5.

[0028] In a specific embodiment of the present invention, the preparation method of the cationic modified enzymatic hydrolysis lignin-based filtration loss reducing agent includes the following steps:

[0029] Step S1: Dissolve enzymatically hydrolyzed lignin in an aqueous formaldehyde solution and carry out a polymerization reaction in the presence of acid to obtain an intermediate solution;

[0030] Step S2: Mix the intermediate solution and the cationic monomer and react to obtain a cationic modified enzymatic hydrolysis lignin-based filtration loss reducer.

[0031] Enzymatically hydrolyzed lignin is a natural polymer extracted from the residue of microbial enzymatic hydrolysis of corn stalks to produce energy ethanol. It retains the original structure of lignin to the greatest extent possible and, compared to lignin, possesses more active groups such as phenolic hydroxyl groups, as well as good adsorption and amphiphilic properties, making it a potential substitute for phenol to improve the environmental performance of products. Furthermore, lignin is insensitive to calcium ions, suggesting the potential for developing calcium-resistant drilling fluid treatment agents. Currently, enzymatically hydrolyzed lignin is widely used in food processing, water treatment agents, and oilfield chemicals. However, there are no reports of cationic modification of enzymatically hydrolyzed lignin to synthesize calcium-resistant drilling fluid treatment agents.

[0032] This invention involves cationic modification of enzymatically hydrolyzed lignin (containing abundant phenolic hydroxyl groups and conjugated double bonds) to synthesize a filtration loss reducer product. The product's molecular structure contains multiple nitrogen adsorption sites, which can provide lone pairs of electrons to form coordinate bonds with calcium ions, allowing the filtration loss reducer molecules to better adsorb onto the clay surface, reducing filtration loss and simultaneously improving calcium resistance. Therefore, the calcium-resistant lignin-based filtration loss reducer prepared by cationic modification of enzymatically hydrolyzed lignin enhances the environmental and practical performance of drilling fluid treatment agents, possessing significant research value and market potential. However, as a natural macromolecule, lignin generally suffers from significant steric hindrance and few reactive groups; its reactivity with cationic monomers is equivalent to physical blending or micro-crosslinking, offering almost no benefit to improving product performance.

[0033] Preferably, the enzymatically hydrolyzed lignin described in this embodiment of the invention is a refined enzymatically hydrolyzed lignin prepared according to ZL201910631105X "A method for preparing enzymatically hydrolyzed lignin, refined enzymatically hydrolyzed lignin, lignin-phenolic resin filtration loss reducer, and drilling fluid filtration loss reducer," produced or purchased by the Drilling Engineering Technology Research Institute of Sinopec Zhongyuan Petroleum Engineering Company; its lignin content is ≥80%, and its phenolic hydroxyl content is ≥3.0 mmol / g. -1 The residual sugar content is less than or equal to 3%, and the ash content is ≤5%.

[0034] In step S1 of this embodiment of the invention, the enzymatically hydrolyzed lignin is first dissolved in formaldehyde (aqueous solution) and stirred until dissolved; the formaldehyde is commercially available and its mass concentration can be 30-40%, generally 37%. Then, in this embodiment of the invention, acid is slowly added to the dissolved liquid, stirred until dissolved, and heated to carry out a polymerization reaction to obtain an intermediate solution.

[0035] The acid is preferably a hydrochloric acid solution with a mass concentration of 30-40%, but is not limited thereto; the mass ratio of the enzymatically hydrolyzed lignin to the hydrochloric acid solution is preferably 10-40:0.1-0.5, more preferably 20-30:0.2-0.4. The polymerization reaction temperature is preferably 85-95℃, more preferably 88-92℃; the polymerization reaction time can be 3-4 hours. The purpose of this step is to enzymatically hydrolyze lignin and formaldehyde to polymerize under acidic conditions to produce resin, with formaldehyde acting as a crosslinking agent.

[0036] In this embodiment of the invention, the cationic monomer 3-acryloyloxy-2-hydroxypropyltrimethylammonium chloride (other ammonium halides may also be used) is preferably used. The cationic monomer is added to the liquid prepared in step S1, stirred to dissolve, and heated to react, thereby obtaining a cationic polymer.

[0037] The structure of the cationic monomer 3-acryloyloxy-2-hydroxypropyltrimethylammonium chloride is as follows; it can be obtained from commercially available products (such as those purchased from Mobil (Shanghai) Biotechnology Co., Ltd., CAS69613-89-4) or synthesized. The specific synthesis method is as follows: acrylic acid and an appropriate amount of water are added to a reaction flask equipped with a reflux condenser. Epichlorohydrin is gradually added (the temperature is controlled not to exceed 30℃ during the addition process). The mixture is reacted under stirring until it becomes transparent. The reaction is maintained at 30℃±1℃ for 2 hours, and then at 45℃±1℃ for 0.5 hours. The temperature is then lowered to below 20℃, and a trimethylamine aqueous solution is slowly added dropwise. After the trimethylamine is completely added, the temperature is raised to 45℃, and the reaction continues for 3 hours. Unreacted raw materials and byproducts are removed by vacuum distillation to obtain the target product with a solid content of approximately 50%.

[0038]

[0039] In step S2 of this embodiment of the invention, the reaction temperature is preferably 98-102°C, and the reaction time is 2-3 hours; the purpose is to cationize the resin, that is, to graft cationic monomers onto the enzymatically hydrolyzed lignin structure.

[0040] After step S2, the preferred embodiment of the present invention further includes: cooling the obtained reaction product to room temperature and spray drying it to obtain a powdered cationic modified enzymatic hydrolysed lignin-based filtration loss reducer.

[0041] Spray drying is a drying method that uses an atomizer with nozzles to disperse a liquid raw material into droplets, and then dries the droplets with hot gas (air, nitrogen, or superheated steam) to obtain a product. In the embodiments of this invention, the inlet temperature of the spray dryer (nozzle) is preferably 200-205°C, and the outlet temperature can be 110-115°C; to match the inlet and outlet temperatures and control indicators such as moisture content, the nozzle diameter can be 0.3 mm. This application embodiment does not have special requirements for product particle size; both powder and granular forms are acceptable; the purpose of spray drying is mainly to obtain a free-flowing powder product with a water content of less than 8%, which is convenient for application.

[0042] The present invention provides a cationic modified enzymatic hydrolysis lignin-based filtration loss reducer prepared by the preparation method described above, which can be a brown solid product, or more specifically, a free-flowing powder product with a water content of less than 8%.

[0043] The structure of the described cationic modified enzymatic hydrolysis lignin-based filtration loss reducer includes alkyl chains, carbon-nitrogen double bonds, and cationic groups; in the example infrared spectroscopy results, at 3003 cm⁻¹... -1 The absorption peaks at that point correspond to CH3 and N. + The stretching vibration peak is 1396 cm⁻¹. -1 The absorption peak at 1456 cm⁻¹ corresponds to the CO stretching vibration peak of the alkyl chain.-1 The absorption peak at that point corresponds to the characteristic vibrational peak of C=N.

[0044] In this embodiment of the invention, the enzymatically hydrolyzed lignin is a mixture of small-molecule lignin rich in phenolic hydroxyl groups. The active sites at the ortho and para positions of the phenolic hydroxyl groups can react, firstly with formaldehyde to form resin, and secondly with cationic monomers such as 3-acryloyloxy-2-hydroxypropyltrimethylammonium chloride, introducing functional groups onto the resin, giving the target product multiple adsorption sites such as nitrogen (see structural formula 1). These sites can provide lone pairs of electrons to form coordination bonds with calcium ions, allowing the filtration loss reducer molecules to be better adsorbed on the clay surface. This, combined with the hydroxyl hydration groups, enhances the calcium resistance of the filtration loss reducer, thereby reducing filtration loss. The product's calcium resistance reaches 10000 mg / L. Experimental results show that at 180℃ / 16h, under a calcium ion concentration of 10000 mg / L, the resulting drilling fluid filter cake has dense pores, effectively preventing the filtrate from entering the formation.

[0045] The main structural formula is shown in Equation 1:

[0046]

[0047] This invention provides the application of cationic modified enzymatic hydrolysis lignin-based filtration loss reducers in drilling fluids, as described above; some embodiments show a calcium ion concentration of 10000 mg / L in the drilling fluid, which can be referred to as calcium-contaminated drilling fluid. The drilling fluid can be various water-based drilling fluids, including conventional components such as bentonite; the dosage of the filtration loss reducer can be 2-5%.

[0048] In summary, the embodiments of the present invention have the following advantages:

[0049] (1) The technical solution provided in this embodiment of the invention uses enzymatically hydrolyzed lignin, formaldehyde, hydrochloric acid, and the cationic monomer 3-acryloyloxy-2-hydroxypropyltrimethylammonium chloride as raw materials. Utilizing the multiple hydroxyl and carboxyl functional groups on the enzymatically hydrolyzed lignin molecule, the cationic monomer 3-acryloyloxy-2-hydroxypropyltrimethylammonium chloride can be grafted onto the enzymatically hydrolyzed lignin through a reaction to synthesize a modified enzymatically hydrolyzed lignin calcium-resistant filtration loss reducer (i.e., a cationic modified enzymatically hydrolyzed lignin filtration loss reducer). This modified enzymatically hydrolyzed lignin calcium-resistant filtration loss reducer has multiple nitrogen adsorption sites, which can provide lone pairs of electrons to form coordinate bonds with calcium ions, allowing the filtration loss reducer molecules to be better adsorbed on the clay surface, reducing filtration loss, improving calcium resistance, and achieving a calcium resistance performance of 10000 mg / L.

[0050] (2) The preparation method of the modified enzymatic hydrolysis lignin anti-calcium filtration loss agent provided in the embodiments of the present invention is simple to operate, the raw materials are readily available, the synthesis time is short, and the synthesis temperature is appropriate.

[0051] (3) The modified enzymatic hydrolysis lignin anti-calcium filtration loss reducer provided in the embodiments of the present invention has good compatibility with various water-based drilling fluids, is easy to use, promotes the technological progress of environmentally friendly anti-pollution drilling fluids, has significant economic and social benefits, and has important application value.

[0052] To better illustrate the present invention, further examples are provided below. In these examples, all original reagents and materials are commercially available, and experimental methods not specifically specified are conventional methods and conditions well-known in the art. The enzymatically hydrolyzed lignin was produced by the Drilling Engineering Technology Research Institute of Sinopec Zhongyuan Petroleum Engineering Company, conforming to the standard "Technical Requirements for Enzymatically Hydrolyzed Lignin" (Q / ZY ZJYY0079-2019), with a lignin content ≥80% and phenolic hydroxyl content ≥3.0 mmol / g. -1 The residual sugar content is less than or equal to 3%, and the ash content is ≤5%.

[0053] Example 1

[0054] A cationic modified enzymatic hydrolyzed lignin filtration loss reducer comprises the following raw materials: 10g of enzymatic hydrolyzed lignin, 20g of formaldehyde (concentration 37%), 0.1g of hydrochloric acid (concentration 36%), and 0.3g of cationic monomer 3-acryloyloxy-2-hydroxypropyltrimethylammonium chloride.

[0055] S1 dissolves enzymatically hydrolyzed lignin in the formaldehyde and stirs to dissolve;

[0056] S2. The hydrochloric acid is slowly added to the liquid prepared in S1, stirred to dissolve, and then heated to 90°C for polymerization for 3 hours.

[0057] S3 adds the cationic monomer 3-acryloyloxy-2-hydroxypropyltrimethylammonium chloride to the liquid prepared in S2, stirs to dissolve, and heats to 100°C for polymerization for 2 hours to obtain the cationic polymer;

[0058] S4. The cationic polymer obtained in step S3 is cooled to room temperature and spray-dried (inlet temperature 200℃~205℃, outlet temperature 110℃~115℃, nozzle diameter 0.3mm) to obtain a free-flowing powder product with a water content of less than 8%, which is the modified enzymatic hydrolysis lignin-based filtration loss reducer. The high temperature and high pressure filtration loss reduction was measured to be 16.4mL.

[0059] Example 2

[0060] A cationic modified enzymatic hydrolyzed lignin filtration loss reducer comprises the following raw materials: 40g of enzymatically hydrolyzed lignin, 60g of formaldehyde (concentration 37%), 0.5g of hydrochloric acid (concentration 36%), and 3g of cationic monomer 3-acryloyloxy-2-hydroxypropyltrimethylammonium chloride.

[0061] S1 dissolves enzymatically hydrolyzed lignin in the formaldehyde and stirs to dissolve;

[0062] S2 slowly adds the hydrochloric acid to the liquid prepared in S1, stirs to dissolve, and heats to 92°C for polymerization for 4 hours;

[0063] S3 adds the cationic monomer 3-acryloyloxy-2-hydroxypropyltrimethylammonium chloride to the liquid prepared in S2, stirs to dissolve, and heats to 102℃ for polymerization for 3 hours to obtain the cationic polymer;

[0064] S4. The cationic polymer obtained in step S3 is cooled to room temperature and spray-dried (inlet temperature 200℃~205℃, outlet temperature 110℃~115℃, nozzle diameter 0.3mm) to obtain a free-flowing powder product with a water content of less than 8%, which is the modified enzymatic hydrolysis lignin-based filtration loss reducer. The high-temperature and high-pressure filtration loss reduction was measured to be 22.6mL.

[0065] Example 3

[0066] A cationic modified enzymatic hydrolyzed lignin cumulative filtration loss agent comprises the following raw materials: 20g of enzymatically hydrolyzed lignin, 30g of formaldehyde (concentration 37%), 0.3g of hydrochloric acid (concentration 36%), and 1g of cationic monomer 3-acryloyloxy-2-hydroxypropyltrimethylammonium chloride.

[0067] S1 dissolves enzymatically hydrolyzed lignin in the formaldehyde and stirs to dissolve;

[0068] S2: The hydrochloric acid is slowly added to the liquid prepared in S1, stirred to dissolve, and then heated to 88°C for polymerization for 3.5 hours.

[0069] S3 adds the cationic monomer 3-acryloyloxy-2-hydroxypropyltrimethylammonium chloride to the liquid prepared in S2, stirs to dissolve, and heats to 98°C for polymerization for 2.5 h to obtain the cationic polymer;

[0070] S4. The cationic polymer obtained in step S3 is cooled to room temperature and spray-dried (inlet temperature 200℃~205℃, outlet temperature 110℃~115℃, nozzle diameter 0.3mm) to obtain a free-flowing powder product with a water content of less than 8%, which is the modified enzymatic hydrolysis lignin anti-calcium filtration loss reducer. The high temperature and high pressure filtration loss was measured to be 18.4mL.

[0071] Example 4

[0072] A cationic modified enzymatic hydrolyzed lignin filtration loss reducer comprises the following raw materials: 30g of enzymatically hydrolyzed lignin, 50g of formaldehyde (concentration 37%), 0.4g of hydrochloric acid (concentration 36%), and 2g of cationic monomer 3-acryloyloxy-2-hydroxypropyltrimethylammonium chloride.

[0073] S1 dissolves enzymatically hydrolyzed lignin in the formaldehyde and stirs to dissolve;

[0074] S2. The hydrochloric acid is slowly added to the liquid prepared in S1, stirred to dissolve, and then heated to 91°C for polymerization for 3.75 hours.

[0075] S3 adds the cationic monomer 3-acryloyloxy-2-hydroxypropyltrimethylammonium chloride to the liquid prepared in S2, stirs to dissolve, and heats to 101°C for polymerization for 2.75 h to obtain the cationic polymer;

[0076] S4. The cationic polymer obtained in step S3 is cooled to room temperature and spray-dried (inlet temperature 200℃~205℃, outlet temperature 110℃~115℃, nozzle diameter 0.3mm) to obtain a free-flowing powder product with a water content of less than 8%, which is the modified enzymatic hydrolysis lignin anti-calcium filtration loss reducer. The high temperature and high pressure filtration loss reduction was measured to be 20.2mL.

[0077] Example 5

[0078] A cationic modified enzymatic hydrolyzed lignin filtration loss reducer comprises the following raw materials: 30g of enzymatically hydrolyzed lignin, 57g of formaldehyde (concentration 37%), 0.35g of hydrochloric acid (concentration 36%), and 2.5g of cationic monomer 3-acryloyloxy-2-hydroxypropyltrimethylammonium chloride.

[0079] S1 dissolves enzymatically hydrolyzed lignin in the formaldehyde and stirs to dissolve;

[0080] S2: The hydrochloric acid is slowly added to the liquid prepared in S1, stirred to dissolve, and then heated to 88°C for polymerization for 3.5 hours.

[0081] S3 adds the cationic monomer 3-acryloyloxy-2-hydroxypropyltrimethylammonium chloride to the liquid prepared in S2, stirs to dissolve, and heats to 98°C for polymerization for 2.5 h to obtain the cationic polymer;

[0082] S4. The cationic polymer obtained in step S3 is cooled to room temperature and spray-dried (inlet temperature 200℃~205℃, outlet temperature 110℃~115℃, nozzle diameter 0.3mm) to obtain a free-flowing powder product with a water content of less than 8%, which is the modified enzymatic hydrolysis lignin-based filtration loss reducer. The high-temperature and high-pressure filtration loss reduction was measured to be 12.0mL.

[0083] The modified enzymatic hydrolysis lignin-based filtration loss reducer sample prepared in Example 5 of this invention was analyzed by infrared spectroscopy using a Fourier transform infrared absorption spectrometer. Figure 1 As shown, at 3381cm -1A strong and broad absorption peak appeared at 3100 cm⁻¹, which is a typical characteristic of the stretching vibration of the hydroxyl group (-OH). Hydroxyl groups are usually present in lignin molecules, indicating that the modified product still retains a portion of the unmodified lignin structure; at 3100 cm⁻¹... -1 The absorption peak at 3003 cm⁻¹ corresponds to the stretching vibration peak of methylene-CH₂, indicating that a condensation reaction has occurred; -1 The absorption peaks at that point correspond to CH3 and N. + The stretching vibration peak is 1600-1500 cm⁻¹. -1 The absorption peaks are usually related to the C=C stretching vibrations of the aromatic ring, indicating that the aromatic structure still exists in the lignin molecule; 1400-1300 cm⁻¹ -1 The absorption peak at 1456 cm⁻¹ may be related to the CH bending vibration and CO stretching vibration, further confirming the presence of lignin molecules; -1 The absorption peak at that location corresponds to the characteristic vibration peak of C=N, indicating that a cationic modified enzymatic hydrolysis lignin-based filtration loss reducer has been successfully synthesized.

[0084] Comparative Example 1:

[0085] A cationic modified phenol-based filtration loss reducer comprises the following raw materials: 30g phenol, 57g formaldehyde (concentration 37%), 0.35g hydrochloric acid (concentration 36%), and 2.5g cationic monomer 3-acryloyloxy-2-hydroxypropyltrimethylammonium chloride.

[0086] S1 Dissolve phenol in the formaldehyde and stir until dissolved;

[0087] S2: The hydrochloric acid is slowly added to the liquid prepared in S1, stirred to dissolve, and then heated to 88°C for polymerization for 3.5 hours.

[0088] S3 adds the cationic monomer 3-acryloyloxy-2-hydroxypropyltrimethylammonium chloride to the liquid prepared in S2, stirs to dissolve, and heats to 98°C for polymerization for 2.5 h to obtain the polymer;

[0089] S4. The polymer obtained in step S3 is cooled to room temperature and spray-dried (inlet temperature 200℃~205℃, outlet temperature 110℃~115℃, nozzle diameter 0.3mm) to obtain a free-flowing powder product with a water content of less than 8%, which is the modified phenol-based filtration loss reducer. The high-temperature and high-pressure filtration loss reduction was measured to be 21.4mL.

[0090] The anti-calcium properties of the products prepared in the examples and comparative examples were tested using SMP. The testing process is as follows:

[0091] (1) Preparation of the base slurry. Add 300 mL of distilled water, 0.56 g of anhydrous sodium carbonate, 12 g of drilling fluid evaluation soil, and 12 g of drilling fluid test slurry bentonite to a high-speed stirring cup in sequence. Stir at 10000 r / min for 20 min, interrupting twice during the process. Scrape off any adhering material from the container wall. Cure in a sealed container at 24℃±3℃ for 24 h to prepare the base slurry. Test the slurry filtration loss at 150℃ and 3.45 MPa according to GB / T 16783.1, section 3.3. The filtration loss should be within the range of 65 mL±10 mL. If the filtration loss is not within this range, adjust the amounts of the two soils appropriately to ensure the base slurry meets the requirements.

[0092] (2) Preparation of test slurry. Add a certain amount of sample (accurate to 0.01 g on a dry basis) to a high-speed stirring cup containing the base slurry, stir at high speed for 15 min, add 12 g of calcium chloride (accurate to 0.01 g), stir at high speed for 15 min, and finally add 8.75 g of anhydrous sodium carbonate (accurate to 0.01 g), stir at high speed for 15 min. During the high-speed stirring process, interrupt the process twice after each addition of a reagent to scrape off any adhering material to the container wall.

[0093] (3) Performance evaluation. The prepared sample slurry was placed in an aging tank and heated at 180℃ for 16 hours. After cooling to room temperature, it was stirred at high speed for 5 minutes. The high-temperature and high-pressure filtration loss of the sample slurry (150℃ / 3.45MPa) was determined according to the requirements of GB / T 16783.1, and the filter cake was collected for SEM testing.

[0094] The morphology of the filter cake formed in drilling fluid by the modified enzymatic hydrolysis lignin-based filtration loss reducer sample prepared in Example 5 was further observed using scanning electron microscopy (SEM). Figure 2 As shown, the surface of the mud cake is relatively dense. This structure forms a barrier on the surface of the mud cake. Even if the filtration reducer adsorbed on the surface of the drilling fluid mud cake forms a dense film due to the pressure difference, it will prevent free water in the drilling fluid from permeating through the mud cake into the formation, thus reducing the permeability of the mud cake, improving the quality of the mud cake, and reducing the filtration loss of the system.

[0095] According to the "Technical Specification for Environmental Performance Evaluation of Drilling Fluids" (SY / T 7467-2020), the products prepared in Example 5 and Comparative Example 1, as well as the biotoxicity EC of SMP, were analyzed. 50 The tests were conducted separately. The results of the tests for calcium resistance and biotoxicity are shown in Table 1.

[0096] Table 1. Effect of Product Dosage Increase on Filtration Loss

[0097]

[0098]

[0099] Tests showed that, using Example 5, adding 2%, 3%, 4%, and 5% of modified enzymatic hydrolysis lignin-based filtration loss reducers significantly improved calcium resistance compared to traditional resin filtration loss reducers (sulfonylmethylphenol resin SMP), while also exhibiting good temperature resistance. As shown in Table 1, when the calcium ion concentration was 10000 mg / L and the addition amount was 5%, the high-temperature and high-pressure filtration loss was 16.8 mL (while SMP was 100 mL).

[0100] For biotoxic EC 50 The test results showed that the product prepared using enzymatically hydrolyzed lignin as raw material has no biotoxicity and is a non-toxic and environmentally friendly product; while SMP and Comparative Example 1 both failed to meet the biotoxicity standards (standard limit EC). 50 (Contains concentrations greater than 30,000 mg / L), posing an environmental risk.

[0101] In addition, the filtration loss of Examples 1 to 5 above is summarized in Table 2.

[0102] Table 2 Filtration loss of products in Examples 1-5

[0103] name Added amount / % High temperature and high pressure filtration loss / mL Example 1 5 16.4 Example 2 5 22.6 Example 3 5 18.4 Example 4 5 20.2 Example 5 5 12.0

[0104] The modified enzymatic hydrolysis lignin-based filtration loss reducer provided by this invention is a brown, free-flowing powder at room temperature. It is easily soluble in water and has good compatibility with various types of water-based drilling fluids. It can be added directly according to the mass / volume ratio and mixed evenly. Dust pollution should be avoided during the addition process.

[0105] The preparation method of this invention is simple to operate and uses readily available raw materials. In summary, the modified enzymatic hydrolysis lignin filtration reducing agent provided by this invention uses industrial waste enzymatic hydrolysis lignin as raw material, which is inexpensive and readily available, has a short synthesis time, appropriate synthesis temperature, generates no waste, and produces a product with excellent anti-calcium properties, meeting on-site requirements. It conforms to the modern "green" chemical industry concept of green and environmentally friendly processes from raw materials to production to products, and can promote the advancement of environmentally friendly and pollution-resistant drilling fluid technology, resulting in significant economic and social benefits and important application value.

[0106] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a cationic modified enzymatic hydrolysis lignin-based filtration loss reducing agent, characterized in that, Includes the following steps: Enzymatically hydrolyzed lignin, formaldehyde, acid, and cationic monomers are mixed in water and reacted to obtain a cationic modified enzymatically hydrolyzed lignin-based filtration loss reducer. The cationic monomer is 3-acryloyloxy-2-hydroxypropyltrimethylammonium halide; the mass ratio of the enzymatically hydrolyzed lignin to the cationic monomer is 10-40:0.3-3.

2. The preparation method according to claim 1, characterized in that, The preparation method includes: Step S1: Dissolve enzymatically hydrolyzed lignin in an aqueous formaldehyde solution and carry out a polymerization reaction in the presence of acid to obtain an intermediate solution; Step S2: Mix the intermediate solution and the cationic monomer and react to obtain a cationic modified enzymatic hydrolysis lignin-based filtration loss reducer.

3. The preparation method according to claim 2, characterized in that, In step S1, the acid is a hydrochloric acid solution with a mass concentration of 30-40%; the mass ratio of the enzymatically hydrolyzed lignin to the hydrochloric acid solution is 10-40:0.1-0.

5.

4. The preparation method according to claim 3, characterized in that, In step S1, the polymerization reaction is carried out at a temperature of 85–95°C for 3–4 hours.

5. The preparation method according to claim 4, characterized in that, In step S2, the reaction temperature is 98–102°C and the reaction time is 2–3 hours.

6. The preparation method according to any one of claims 2-5, characterized in that, Step S2 further includes: cooling the obtained reaction product to room temperature and spray drying it to obtain a powdered cationic modified enzymatic hydrolysed lignin filtration loss reducer.

7. The preparation method according to claim 6, characterized in that, The inlet temperature of the spray dryer is 200-205℃, and the outlet temperature is 110-115℃.

8. The cationic modified enzymatic hydrolysis lignin-based filtration loss reducer obtained by the preparation method according to any one of claims 1-7.

9. The application of the cationic modified enzymatic hydrolysis lignin-based filtration loss reducer as described in claim 8 in drilling fluid.

10. The application according to claim 9, characterized in that, The calcium ion concentration in the drilling fluid is below 10,000 mg / L.

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