Zwitterionic petroleum drilling aid and method of making same

Abstract

The application discloses a zwitterionic petroleum drilling aid and a preparation method thereof, and comprises the following steps: S1, trace oxidation is performed on quaternary ammonium chitosan and sulfonated chitosan respectively; S2, Schiff base formation and reduction are performed on the oxidized quaternary ammonium chitosan and double-end aminated hydrophobic long chains; and S3, Schiff base formation and reduction are performed on the reduced quaternary ammonium chitosan and the oxidized sulfonated chitosan. The application realizes double inhibition of filtration loss effect by constructing a unique zwitterionic structure, simultaneously maximally plays a reverse polyelectrolyte effect, improves the viscosity increasing and shear force increasing capacity of a drilling fluid under high temperature and high salinity, and the product structure has strong designability and can meet different working conditions according to requirements.

Description

Technical Field

[0001] This invention relates to the field of petroleum drilling additives technology, and in particular to an amphoteric petroleum drilling additive and its preparation method. Background Technology

[0002] With the depletion of shallow and medium-deep oil and gas resources and the increasing demand for oil and gas, the extension of oil and gas exploration to deep and ultra-deep areas has become an inevitable trend, placing more stringent requirements on oil drilling fluid additives. Traditional drilling fluid additives (such as conventional polymers and lignin sulfonates) are prone to molecular chain thermal degradation, chemical structure destruction, and group dehydration, leading to uncontrolled rheology, a surge in filtration loss, and failure of wellbore stabilization, which in turn causes a series of major engineering problems such as stuck pipe, lost circulation, and well collapse. Therefore, developing next-generation drilling fluid additives that are inherently resistant to high temperatures, highly resistant to salt and calcium deposits, and can synergistically achieve strong inhibition and optimal rheology is key to overcoming the technical bottlenecks of deep and ultra-deep drilling and achieving safe and efficient exploration and development.

[0003] Patent 202310962104.X discloses a chitosan graft copolymer, its preparation method, and drilling fluid. This patent uses chitosan as the main chain and grafts multiple groups onto it, which is not only safe and non-toxic but also improves the filtration loss reduction performance. However, although the chitosan graft copolymer has anionic carboxylate and cationic quaternary ammonium salt grafted onto the main chain, the molecular structure is not well regulated. The randomly distributed amphoteric groups may cause the charge to "internal cancel" and reduce the effective adsorption capacity. At the same time, it lacks the synergistic effect of hydrophobic segments, resulting in limited sealing and lubrication properties. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide an amphoteric petroleum drilling additive and its preparation method, so as to solve the problems of poor amphoteric ion distribution performance of existing drilling fluid additives, resulting in weak salt resistance and filtration loss reduction effect and insufficient viscosity-increasing ability at high temperatures.

[0005] The objective of this invention is achieved through the following technical solution: an amphoteric petroleum drilling additive, prepared according to the following steps. S1. Quaternized chitosan and sulfonated chitosan are subjected to micro-oxidation respectively; S2. Oxidized quaternized chitosan undergoes Schiff base formation and reduction with double-terminated hydrophobic long chains; S3. Reduced quaternized chitosan and oxidized sulfonated chitosan undergo Schiff base formation and reduction.

[0006] Preferably, the quaternized chitosan is prepared according to the following steps: S1. Disperse chitosan in a solvent and add sodium hydroxide to adjust the pH to alkaline; S2. Add glycidyltrimethylammonium chloride, heat to 75-85℃, and stir at a constant temperature for 8-12 hours.

[0007] Preferably, the sulfonated chitosan is prepared according to the following steps: S1. Disperse chitosan in a solvent, control the temperature to 0-5℃, and slowly add chlorosulfonic acid dropwise while stirring; S2. After the addition is complete, raise the temperature to 65-75℃ and stir the reaction at a constant temperature for 3-5 hours.

[0008] Preferably, in step S1, the quaternized chitosan and sulfonated chitosan are added to an acetic acid solution, the pH is adjusted to 3.0-3.5, the temperature is controlled to 0-4℃, sodium periodate solution is slowly added dropwise and the reaction is stirred for 1 hour before quenching.

[0009] Preferably, in step S1, the molar ratio of the quaternized chitosan or sulfonated chitosan to the sodium periodate is 1:0.05-0.1.

[0010] Preferably, the double-terminated hydrophobic long chain is one of ethylenediamine, 1,6-hexanediamine, 1,10-decanediamine, 4,4'-diaminodicyclohexylmethane, and polyether diamine.

[0011] Preferably, in step S2, the oxidized quaternized chitosan is dissolved in a weakly acidic solution, a double-terminated hydrophobic long chain is added, the mixture is stirred at room temperature for 4-6 hours, sodium cyanoborohydride is added in batches, and the mixture is stirred for 24 hours.

[0012] Preferably, in step S2, the molar ratio of the oxidized quaternized chitosan to the bi-terminated hydrophobic long chain is 1:2-3.

[0013] Preferably, in step S3, the reduced quaternized chitosan and the oxidized sulfonated chitosan are added together to a weakly acidic solution and stirred at room temperature for 4-6 hours. Sodium cyanoborohydride is then added in batches and stirred for 24 hours.

[0014] The present invention has the following advantages: 1. This invention discloses a method for preparing an amphoteric petroleum drilling additive. Quaternized chitosan (as a cationic group) and sulfonated chitosan (as anionic group) are branched onto the two ends of a hydrophobic long chain via high-temperature resistant secondary amine bonds, constructing a unique ABA-type amphoteric organic additive. The cationic segment of this additive can be tightly adsorbed onto the negatively charged clay surface through strong electrostatic interaction. The sulfonated anionic segment, after hydration, forms a dense hydration film, thickening the coating and enhancing the system's stability. The hydrophobic long chain connecting arms form a physical barrier between clay layers, further physically preventing water molecules from entering, achieving "dual inhibition." Compared to random dispersion... The amphoteric groups of the fabric effectively avoid the problem of reduced adsorption capacity caused by "internal cancellation" of charges, thus improving the overall filtration efficiency. At the same time, this unique structure physically isolates the positive and negative charges into two independent blocks. When salt invades, the salt ions quickly shield the electrostatic attraction between the two blocks, triggering the molecular chain to change from a tightly coiled C-shape to a fully extended long chain state. Compared with the random extension caused by the random distribution of positive and negative charges on the molecular chain, this structure can maximize the extension of the molecular chain, fully utilize the anti-polyelectrolyte effect, and enable the drilling fluid to maintain a high viscosity under high temperature and high salt conditions, thus enhancing its ability to carry cuttings. 2. This invention uses chitosan as a raw material for graft modification. The raw material is widely available, inexpensive, non-toxic, and biodegradable, which aligns with the development direction of green chemistry. At the same time, both quaternized chitosan and sulfonated chitosan can be prepared under conventional conditions, ensuring a stable supply of raw materials. The overall process reaction conditions are mild and easy to control, and the product structure is highly designable. By adjusting the ratio of quaternized chitosan to sulfonated chitosan, the length of the hydrophobic chain, and the degree of oxidation, the charge density, hydrophobicity, and molecular weight in the ABA structure can be flexibly controlled, thereby customizing the performance required for different drilling conditions. Detailed Implementation

[0015] 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.

[0016] An amphoteric petroleum drilling additive is prepared according to the following steps. S1. Quaternized chitosan and sulfonated chitosan were oxidized with sodium periodate. Sodium periodate can break the C2-C3 bond of the glucosamine unit on the chitosan molecular chain and oxidize the C2 and C3 positions to aldehyde groups respectively, introducing reactive sites and completely preserving the main chain structure of chitosan. S2. The quaternized chitosan after oxidation forms a Schiff base (imine) by attaching an aldehyde group with a reactive site to one end of a bi-terminated hydrophobic long chain. The Schiff base is unstable and is reduced with sodium cyanoborohydride to generate a more stable secondary amine bond, thus grafting a hydrophobic long chain structure onto the quaternized chitosan. S3. The amino groups at the ends of the hydrophobic long chains grafted onto the reduced quaternized chitosan form Schiff bases with the oxidized sulfonated chitosan containing aldehyde groups, and are then reduced with sodium cyanoborohydride to finally form an amphoteric long-chain organic compound of A (cat-grafted chitosan) - B (hydrophobic long chain) - A (anion-grafted chitosan). Example 1

[0017] An amphoteric petroleum drilling additive is prepared according to the following steps. 1. Synthesis of quaternized chitosan: 155g of chitosan with a degree of deacetylation greater than 95% and a degree of polymerization n of 48 was dispersed in isopropanol / water solution. Sodium hydroxide solution was added dropwise under stirring to adjust the pH value to 8-9. 12.13g of glycidyltrimethylammonium chloride was added and the temperature was raised to 80℃. The reaction was stirred at a constant temperature for 12 h. After cooling, the precipitate was collected by filtration, washed successively with anhydrous ethanol, and dried under vacuum at 50℃ to obtain the product. 2. Synthesis of O-sulfonated chitosan: 155g of chitosan with a degree of deacetylation greater than 95% was dispersed in formamide solvent. The temperature was controlled at 0-5℃ using an ice bath. 0.06mol of chlorosulfonic acid was slowly added dropwise as a sulfonating agent with stirring, and the internal temperature was controlled to be less than 5℃. After the addition was complete, the ice bath was removed, the temperature was raised to 70℃, and the reaction was kept at a constant temperature for 4h. After cooling, the reaction solution was slowly poured into 5-6 times the volume of anhydrous ethanol to precipitate the product. The product was then filtered and dried under vacuum to obtain the final product. 3. Introduction of active sites: Quaternized chitosan is added to 1% acetic acid solution, the pH is adjusted to 3.0-3.5, the temperature is controlled at 0-4℃, 0.001mol sodium periodate solution is slowly added dropwise under light-protected conditions and the reaction is stirred for 1h. Ethylene glycol of the same molar amount as sodium periodate is added to quench for 30min. The reaction solution is poured into 5-6 times the volume of anhydrous ethanol to precipitate, and the mixture is filtered and vacuum dried to obtain oxidized quaternized chitosan. Similarly, sulfonated chitosan is also subjected to aldehyde-based treatment. 4. Grafting hydrophobic long chains: Aldehyde-treated quaternized chitosan was dissolved in phosphate buffer at pH 6.5, and 16g of polyether diamine D-400 was added. The mixture was stirred at room temperature for 6 hours. Sodium cyanoborohydride was added in batches with an interval of 1 hour between each batch, and the mixture was stirred for 24 hours. The reaction solution was poured into 5-6 times the volume of anhydrous ethanol to precipitate the precipitate. The precipitate was filtered, washed with anhydrous ethanol, and dried under vacuum. 5. ABA Synthesis: Two intermediates in equal molar amounts were dissolved together in pH 6.5 phosphate buffer and stirred at room temperature for 6 h. Sodium cyanoborohydride was added in batches with an interval of 1 h between each batch, and the mixture was stirred for 24 h. The reaction solution was poured into 5-6 volumes of anhydrous ethanol to precipitate the precipitate. The precipitate was filtered, washed with anhydrous ethanol, and dried under vacuum to obtain the ABA. Example 2

[0018] An amphoteric petroleum drilling additive is prepared according to the following steps. 1. Synthesis of quaternized chitosan: 155g of chitosan with a degree of deacetylation greater than 95% and a degree of polymerization n of 48 was dispersed in an isopropanol / water solution. Sodium hydroxide solution was added dropwise under stirring to adjust the pH to 8-9. 12.13g of glycidyltrimethylammonium chloride was added and the temperature was raised to 80℃. The reaction was stirred at a constant temperature for 12 h. After cooling, the precipitate was collected by filtration, washed successively with anhydrous ethanol, and dried under vacuum at 50℃ to obtain the final product. 2. Synthesis of O-sulfonated chitosan: 155g of chitosan with a degree of deacetylation greater than 95% was dispersed in formamide solvent. The temperature was controlled at 0-5℃ using an ice bath. 0.06mol of chlorosulfonic acid was slowly added dropwise as a sulfonating agent with stirring, and the internal temperature was controlled to be less than 5℃. After the addition was complete, the ice bath was removed, the temperature was raised to 70℃, and the reaction was kept at a constant temperature for 4h. After cooling, the reaction solution was slowly poured into 5-6 times the volume of anhydrous ethanol to precipitate the product. The product was then filtered and dried under vacuum to obtain the final product. 3. Introduction of active sites: Quaternized chitosan is added to 1% acetic acid solution, the pH is adjusted to 3.0-3.5, the temperature is controlled at 0-4℃, 0.002mol sodium periodate solution is slowly added dropwise under light-protected conditions and the reaction is stirred for 1h. Ethylene glycol with an equimolar amount of sodium periodate is added to quench the reaction for 30min. The reaction solution is poured into 5-6 times the volume of anhydrous ethanol to precipitate the precipitate. The precipitate is obtained by vacuum drying after filtration. Similarly, sulfonated chitosan is also subjected to aldehyde-based treatment. 4. Grafting hydrophobic long chains: Aldehyde-treated quaternized chitosan was dissolved in phosphate buffer at pH 6.5, and 24g of polyether diamine D-400 was added. The mixture was stirred at room temperature for 6 hours. Sodium cyanoborohydride was added in batches with an interval of 1 hour between each batch, and the mixture was stirred for 24 hours. The reaction solution was poured into 5-6 times the volume of anhydrous ethanol to precipitate the precipitate. The precipitate was filtered, washed with anhydrous ethanol, and dried under vacuum. 5. ABA Synthesis: Two intermediates in equal molar amounts were dissolved together in pH 6.5 phosphate buffer and stirred at room temperature for 6 h. Sodium cyanoborohydride was added in batches with an interval of 1 h between each batch, and the mixture was stirred for 24 h. The reaction solution was poured into 5-6 volumes of anhydrous ethanol to precipitate the precipitate. The precipitate was filtered, washed with anhydrous ethanol, and dried under vacuum to obtain the ABA. Example 3

[0019] An amphoteric petroleum drilling additive is prepared according to the following steps. 1. Synthesis of quaternized chitosan: 155g of chitosan with a degree of deacetylation greater than 95% and a degree of polymerization n of 48 was dispersed in isopropanol / water solution. Sodium hydroxide solution was added dropwise under stirring to adjust the pH value to 8-9. 12.13g of glycidyltrimethylammonium chloride was added and the temperature was raised to 80℃. The reaction was stirred at a constant temperature for 12 h. After cooling, the precipitate was collected by filtration, washed successively with anhydrous ethanol, and dried under vacuum at 50℃ to obtain the product. 2. Synthesis of O-sulfonated chitosan: 161g of chitosan with a degree of deacetylation greater than 95% was dispersed in formamide solvent. The temperature was controlled at 0-5℃ using an ice bath. 0.06mol of chlorosulfonic acid was slowly added dropwise as a sulfonating agent with stirring, and the internal temperature was controlled to be less than 5℃. After the addition was completed, the ice bath was removed, the temperature was raised to 70℃, and the reaction was kept at a constant temperature for 4h. After cooling, the reaction solution was slowly poured into 5-6 times the volume of anhydrous ethanol to precipitate the product. The product was then filtered and dried under vacuum to obtain the final product. 3. Introduction of active sites: Quaternized chitosan is added to 1% acetic acid solution, the pH is adjusted to 3.0-3.5, the temperature is controlled at 0-4℃, 0.001mol sodium periodate solution is slowly added dropwise under light-protected conditions and the reaction is stirred for 1h. Ethylene glycol of the same molar amount as sodium periodate is added to quench for 30min. The reaction solution is poured into 5-6 times the volume of anhydrous ethanol to precipitate, and the mixture is filtered and vacuum dried to obtain oxidized quaternized chitosan. Similarly, sulfonated chitosan is also subjected to aldehyde-based treatment. 4. Grafting of hydrophobic long chains: Aldehyde-treated quaternized chitosan was dissolved in phosphate buffer at pH 6.5, and 2.4 g of ethylenediamine was added. The mixture was stirred at room temperature for 6 h. Sodium cyanoborohydride was added in batches with an interval of 1 h between each batch, and the mixture was stirred for 24 h. The reaction solution was poured into 5-6 volumes of anhydrous ethanol to precipitate the precipitate. The precipitate was filtered, washed with anhydrous ethanol, and dried under vacuum. 5. ABA Synthesis: Two intermediates in equal molar amounts were dissolved together in pH 6.5 phosphate buffer and stirred at room temperature for 6 h. Sodium cyanoborohydride was added in batches with an interval of 1 h between each batch, and the mixture was stirred for 24 h. The reaction solution was poured into 5-6 volumes of anhydrous ethanol to precipitate the precipitate. The precipitate was filtered, washed with anhydrous ethanol, and dried under vacuum to obtain the ABA.

[0020] Comparative Example A zwitterionic petroleum drilling additive is prepared according to the following steps: 80g of chitosan with a degree of deacetylation greater than 95% and a degree of polymerization n of 48 is dissolved in a 1% acetic acid solution. 6g of ammonium persulfate is added under nitrogen protection. 410g of 2-acrylamide-2-methylpropanesulfonic acid is weighed and prepared into a solution, which is then added dropwise to the reaction solution. The mixture is stirred at 60℃ for 4h under nitrogen protection. After cooling to room temperature, the solution is adjusted to neutral with sodium hydroxide. Precipitation is performed using a mixed solvent and vacuum drying is carried out. The dried product is prepared into a reaction solution with 150g of glycidyltrimethylammonium chloride and reacted at 60-70℃ for 10-12h. After precipitation with acetone, the product is vacuum dried to obtain zwitterionic modified chitosan.

[0021] Performance Evaluation Preparation of the base slurry: Slowly add 16g of bentonite to 400mL of distilled water under stirring, then add 1.2g of sodium carbonate, and seal and cure at room temperature for 24h to prepare the bentonite base slurry.

[0022] Take 400 mL of base slurry, add 10% (40 g) of sodium chloride, and stir at 8000 r / min for 20 min. Then add 2% (8 g) of different filtration loss reducing agents and stir at 8000 r / min for 20 min to obtain drilling fluid samples. Pour the samples into an aging tank and heat-roll at 180℃ for 16 h to age the base slurry and drilling fluid samples.

[0023] The drilling fluid samples and base fluid rheological and filtration properties before and after aging were tested according to the relevant methods in SY / T5621-1993 "Drilling Fluid Testing Procedures". The results are shown in the table below.

[0024] As shown in the table, adding the modified chitosan prepared by the present invention and the comparative example can significantly reduce the filtration loss of the salt-based slurry. At the same time, the ABA-type zwitterionic modified chitosan prepared by the present invention has less filtration loss at both high and room temperatures compared with the modified chitosan prepared by the comparative example, proving that the introduced hydrophobic long chain structure helps to improve the filtration loss reduction performance. The apparent viscosity of Examples 1-3 is higher than that of the comparative example, and the viscosity reduction at high temperature is also much lower than that of the comparative example, proving that the anionic and cationic structure with branches at both ends of the hydrophobic long chain performs better in anti-polyelectrolyte effect than the structure with alternating branches of anionic and cationic structures on the chitosan main chain, which is more conducive to maintaining the viscosity of drilling fluid under high temperature and high salt conditions.

[0025] 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 an amphoteric petroleum drilling additive, characterized in that, Includes the following steps, S1. Quaternized chitosan and sulfonated chitosan are subjected to micro-oxidation respectively; S2. Oxidized quaternized chitosan undergoes Schiff base formation and reduction with double-terminated hydrophobic long chains; S3. Reduced quaternized chitosan and oxidized sulfonated chitosan undergo Schiff base formation and reduction.

2. The method for preparing an amphoteric petroleum drilling additive according to claim 1, characterized in that, The quaternized chitosan was prepared according to the following steps. S1. Disperse chitosan in a solvent and add sodium hydroxide to adjust the pH to alkaline; S2. Add glycidyltrimethylammonium chloride, heat to 75-85℃, and stir at a constant temperature for 8-12 hours.

3. The method for preparing an amphoteric petroleum drilling additive according to claim 1, characterized in that, The sulfonated chitosan was prepared according to the following steps. S1. Disperse chitosan in a solvent, control the temperature to 0-5℃, and slowly add chlorosulfonic acid dropwise while stirring; S2. After the addition is complete, raise the temperature to 65-75℃ and stir the reaction at a constant temperature for 3-5 hours.

4. The method for preparing an amphoteric petroleum drilling additive according to claim 1, characterized in that, In step S1, the quaternized chitosan and sulfonated chitosan are added to an acetic acid solution, the pH is adjusted to 3.0-3.5, the temperature is controlled to 0-4℃, sodium periodate solution is slowly added dropwise and the reaction is stirred for 1 hour before quenching.

5. The method for preparing an amphoteric petroleum drilling additive according to claim 1, characterized in that: In step S1, the molar ratio of the quaternized chitosan or sulfonated chitosan to the sodium periodate is 1:0.05-0.

1.

6. The method for preparing an amphoteric petroleum drilling additive according to claim 1, characterized in that, The dual-terminated amination hydrophobic long chain is one of ethylenediamine, 1,6-hexanediamine, 1,10-decanediamine, 4,4'-diaminodicyclohexylmethane, and polyether diamine.

7. The method for preparing an amphoteric petroleum drilling additive according to claim 1, characterized in that, In step S2, the oxidized quaternized chitosan is dissolved in a weakly acidic solution, and a double-terminated hydrophobic long chain is added. The mixture is stirred at room temperature for 4-6 hours, and sodium cyanoborohydride is added in batches. The mixture is stirred for 24 hours.

8. The method for preparing an amphoteric petroleum drilling additive according to claim 1, characterized in that, In step S2, the molar ratio of the oxidized quaternized chitosan to the bi-terminated hydrophobic long chain is 1:2-3.

9. The method for preparing an amphoteric petroleum drilling additive according to claim 1, characterized in that: In step S3, the reduced quaternized chitosan and the oxidized sulfonated chitosan are added together to a weakly acidic solution and stirred at room temperature for 4-6 hours. Sodium cyanoborohydride is then added in batches and stirred for 24 hours.

10. An amphoteric petroleum drilling additive, characterized in that, Obtained based on any one of the methods of claims 1-9.

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