An interface modified amphoteric polyacrylamide fluid loss additive, a preparation method and application thereof

Abstract

The application provides a cationic polyacrylamide filtrate reducer, a preparation method and application thereof, and can simultaneously introduce sulfonic acid groups, rigid benzene rings and quaternary ammonium groups. The presence of these various groups improves the temperature resistance and salt resistance of the filtrate reducer, and the filtrate reducer has the functions of anti-swelling and inhibitor. A cationic polyacrylamide filtrate reducer with the functions of anti-swelling and filtrate reduction is developed, which solves the problems of adding multiple additives and complicated configuration process in operation, and greatly improves the operation efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of oil and gas well drilling and oil field chemical additives, and more particularly to a filtrate reducer for oil well drilling, and a preparation method and application thereof. BACKGROUND

[0002] The mud filtrate reducer is used in large quantities during drilling, and plays an important role in maintaining the performance of drilling fluid and ensuring safe and efficient drilling. With the deepening of oil and gas well drilling, high temperature, high pressure and high salt formation environment frequently occurs, which brings great difficulties to control the water loss and rheological properties of drilling fluid, and puts forward higher requirements for the development of new filtrate reducers to adapt to complex drilling environment.

[0003] Since the functional groups are the key groups on the molecules of the treatment agent, they endow the polymer with functionality, and the properties are directly related to the application performance of the treatment agent. In order to improve the operability of molecular design, Wang Zhonghua (1 Analysis of the Status of Drilling Fluid Treatment Agent and Discussion on Synthetic Design, Wang Zhonghua, China and Foreign Energy, 2012, 17 (9): 32-40) proposed the concepts of dominant and non-dominant functional groups in the selection and design of groups. (1) Dominant functional group: the dominant functional group refers to the functional group in the molecule which plays a key role and has a greater impact on the performance of the product. According to the function and property of the group, it is divided into adsorption group, hydration group and selective group. Among them, the adsorption groups mainly include nonionic and cationic groups. Nonionic groups include amide groups, hydroxyl groups, amine groups; cationic groups include main chain quaternary ammonium groups (weak adsorption ability due to steric hindrance) and side chain quaternary ammonium groups (strong adsorption ability) or quaternary phosphonium groups. The hydration groups mainly include sulfonic acid groups, carboxyl groups and phosphonic acid groups. (2) Non-dominant functional group: the non-dominant functional group refers to the functional group which can play a certain hydration or adsorption role, but has little effect on the performance of the treatment agent, and together with the dominant functional group, it is beneficial to improve the comprehensive performance of the polymer. It includes hydrophobic groups that can produce hydrophobic association, improve the salt resistance and inhibition of the molecule, secondary adsorption groups on the main chain that have adsorption effect, can improve the solubility and adsorption on clay particles, and secondary hydration groups on the main chain that have hydration effect, can improve the solubility and hydration capacity. The introduction of benzene ring can greatly improve the rigidity of the polymer, and the hydration groups are not easy to approach each other, which is beneficial to improve the temperature resistance and salt resistance.

[0004] Because the zwitterionic polymer contains both cationic groups with adsorption and hydration dual role and a large number of hydrated groups, a dense hydration layer can be formed around the clay particles, preventing and delaying the contact of water molecules with the clay surface, preventing the hydration and swelling of clay particles, and having the advantages of high temperature loss reduction performance and salt resistance, etc. Its development and application have gradually attracted attention (Wang Zhonghua, Current Situation and Development Trend of Surface Active Agents for Oilfield, [J] Henan Chemical Industry, 2006, 23(1): 4-6; Zhang Keqin, Lu Yanli, et al. Analysis of 20 Years Development of Foreign Drilling Fluid Additives, [J] Drilling Fluids and Completion Fluids, 2005, (22) 5: 1-4)

[0005] In addition, the zwitterionic polymer can be used in combination with anionic polymers and can also be used in combination with cationic polymers, and has been widely used in oilfield development. Compared with anionic or non-ionic polymer fluid loss reducers, zwitterionic polymers have obvious advantages. On the one hand, they can enhance the inhibition of the entire mud system, and on the other hand, they can improve the compatibility between various additives, ensuring that the mud system is not dispersed and has low solid content, thereby solving the conflict between the inhibition and rheological adjustment of polymer drilling fluids.

[0006] The existing oil well cement zwitterionic fluid loss reducer generally uses monomer acrylic acid and acrylamide (AM) as the first and second monomers, and other third and fourth monomers such as anionic monomer 2-acrylamido-2-methylpropanesulfonic acid (AMPS), methacrylic acid, dibasic acid, and cationic monomer dimethyldiallylammonium chloride, (meth) acryloyloxyethyl ammonium chloride, etc. monomers rich in adsorption groups, to form a multi-component copolymer (CN 101691485 B, CN 113563510 B, CN 114805680 A). The main problems are:

[0007] (1) Some monomers have been implemented in industrial production, but the product production process is complex, the product yield is low, and the cost is high, which restricts further application, so further research is needed on the synthesis method and process to form an economically feasible production process as soon as possible. And sometimes the activity gap of different monomers in the existing monomer combination is large, the reactivity is different, and it is difficult to obtain a uniformly distributed copolymer. The difference between monomer types and raw material batches also easily causes quality fluctuations of the product, which is not easy to control. The development of special raw materials (monomers) first considers the group, and the core is to meet the need to improve the performance of drilling fluid additives, and the stability is better, the price is appropriate, or the performance-price ratio of the synthesized product is more advantageous. Secondly, consider the implementation, polymerization characteristics of monomers, and the performance of polymers. The method cannot be too complex, which is conducive to industrialization.

[0008] (2) Conventional polymer filtrate reducers are prone to cause the problems of the increase of the viscosity and shear force of the drilling fluid, the deterioration of the filter cake quality, the difficulty in controlling the high temperature and high pressure filtration loss, and the like, and are prone to cause downhole complications. The currently used filtrate reducers SMP, the viscosity reducers SMC and SMK, and the modified products having both functions, need to be used in combination under the conditions of high solid phase and high salinity, and need to be added in a large amount, resulting in the increase of the cost of the drilling fluid, the increase of the labor intensity, and the poor temperature resistance and salt resistance.

[0009] (3) The current low molecular weight filtrate reducer is a liquid product, which is not conducive to storage and transportation. The reverse suspension polymerization can directly obtain a solid product (CN 101591527 B), but the production efficiency is low, the energy consumption is high, flammable oil is used as the dispersion phase in the process, the process is complex and difficult to control, and the product quality fluctuation is difficult to control. The aqueous solution polymerization process is convenient and easy to control, and various complex component products such as copolymerization and graft modification can be produced.

[0010] Since the existing filtrate reducers have single functions, the inhibitors need to be added simultaneously during the field construction, which increases the cost of the drilling fluid, increases the labor intensity of the workers, and makes the composition of the drilling fluid complex, thereby increasing the difficulty in maintenance and treatment. SUMMARY

[0011] In view of the above problems existing in the current filtrate reducer technology, the application provides a branched modified amphoteric polyacrylamide filtrate reducer, a preparation method and applications thereof. The branched modified amphoteric polyacrylamide filtrate reducer is obtained by adjusting the pH of the polymer modification system of the micro-crosslinked non-ionic polyacrylamide polymer matrix by KOH, and introducing strong inhibitory ions K+, sulfonate, rigid benzene ring and quaternary ammonium groups, so as to improve the performance of the filtrate reducer and simultaneously have the function of anti-swelling inhibitor. The branched modified amphoteric polyacrylamide filtrate reducer has the functions of anti-swelling and filtrate reduction, and solves the problems of the need to add multiple additives and the complex configuration process in the drilling operation, thereby greatly improving the operation efficiency.

[0012] The technical scheme adopted by the application is as follows: a branched modified amphoteric polyacrylamide filtrate reducer is prepared from the following raw materials by weight: 400 parts of deionized water, 100 parts of acrylamide, 2-5 parts of a crosslinking agent N,N-methylenebisacrylamide, 15-16 parts of an oxidizing agent, 12-15 parts of a reducing agent, 3-8 parts of a molecular weight regulator sodium methallyl sulfonate, 15-18 parts of potassium hydroxide, and 15-18 parts of potassium hypochlorite.

[0013] The oxidizing agent is selected from one or more of ammonium persulfate, sodium persulfate and tert-butyl hydroperoxide, and the reducing agent is selected from one or more of sodium pyrosulfite, sodium sulfite and ferrous sulfate.

[0014] A preparation method of a modified amphoteric polyacrylamide filtrate reducer, characterized by comprising the following steps:

[0015] (1) Micro-crosslinking nonionic polyacrylamide solution synthesis:

[0016] 1) Dissolve acrylamide and crosslinking agent N,N-methylene bisacrylamide in deionized water according to the mass ratio, and obtain a monomer solution with a concentration of 20%-25%;

[0017] 2) After the monomer solution of step 1 is vacuum degassed, add molecular weight regulator sodium methallyl sulfonate, sodium metabisulfite and sodium persulfate, adjust the pH value to 6.5-7.5, adjust the temperature to 40-45°C, fill nitrogen, and start the reaction for 50-60min;

[0018] 3) Adjust the temperature to 60-65°C, continue to react for 2-3h, add 0.1-1% of the polymer mass of post-treatment agent sodium bisulfite, and continue to age for 30min to obtain a micro-crosslinking nonionic polyacrylamide solution;

[0019] (2) Hofmann degradation etherification modification:

[0020] 1) After the micro-crosslinking nonionic polyacrylamide solution of step 3) is cooled to room temperature of 25°C, ice water bath to 0°C, then add KOH solution, KClO solution, control the molar ratio of CONH2, OH, ClO in the reaction system to be 1:(0.6-1):(0.2-0.5), seal and shake, and continue ice water bath for 20min, then naturally warm up to 25°C, during the warming process, Hofmann degradation reaction occurs;

[0021] 2) During the Hofmann degradation reaction, add sulfonated-3-phenoxy-2-hydroxypropyl trimethyl ammonium chloride formaldehyde resin to introduce sulfonic acid group, rigid benzene ring and quaternary ammonium salt-resistant group, adjust the pH to weakly acidic 6-7, and dry by roller to obtain modified amphoteric polyacrylamide high-temperature filtrate reducer.

[0022] The modified amphoteric polyacrylamide forms a space network structure in the drilling fluid, and the branched chain is relatively complete. This is mainly because the modified amphoteric polyacrylamide contains cationic groups and strong inhibitory ions K+, the cationic groups form a dense space grid structure and inter-particle bridging through adsorption between the clay, and the strong inhibitory ions K+ can prevent the hydration and peeling of soft shale and hard brittle shale, so as to achieve the effect of stabilizing the hole wall; on the other hand, the strong hydration group sulfonic acid group, rigid benzene ring and quaternary ammonium group on the polymer molecular chain of the modified amphoteric polyacrylamide provide a higher viscoelastic hydration film, have a good hole plugging effect, make the filter cake more dense, and the filtration loss is lower.

[0023] The present application obtains a liquid product by water solution polymerization, branch modification, a solid product by drum drying process, and crushing and screening. The whole process is simple and controllable, the product performance is stable, the safety and environmental protection are good, and large-scale production can be realized. The filtrate reducer can be used in oil and natural gas drilling and production operations to reduce the penetration of liquid phase in mud to the formation, and has the functions of reducing mud viscosity and inhibiting shale expansion and hydration. DETAILED DESCRIPTION

[0024] The present application is further described below in combination with examples.

[0025] Micro-crosslinking non-ionic polyacrylamide solution (NPAM solution for short) synthesis: 100 parts of acrylamide and 4 parts of crosslinking agent N,N-methylene bisacrylamide are dissolved in 400 parts of deionized water according to the mass ratio, to obtain a monomer solution with a concentration of 25%; after vacuum degassing of the above monomer solution, 5 parts of molecular weight regulator sodium methallyl sulfonate, 12 parts of sodium metabisulfite, and 15 parts of sodium persulfate are added, the pH value is adjusted to 7.0, the temperature is adjusted to 45°C, nitrogen is filled, and the reaction is started for 60 min; the temperature is adjusted to 65°C; the reaction is continued for 2.5 h, 0.5% of polymer mass of sodium bisulfite treatment agent is added, and the aging is continued for 30 min, to obtain a micro-crosslinking non-ionic polyacrylamide solution. Example 1

[0026] After the micro-crosslinking non-ionic polyacrylamide solution is cooled to 25°C room temperature, ice water bath is performed to 0°C, KOH solution and KClO solution are added, the molar ratio of -CONH2, OH-, and ClO- in the reaction system is controlled to be 1:0.6:0.2, it is sealed and shaken, and ice water bath is continued for 20 min, and then it is naturally restored to 25°C. In this warming process, Hofmann degradation reaction occurs; sulfonated-3-phenoxy-2-hydroxypropyl trimethylammonium chloride formaldehyde resin is added during the Hofmann degradation reaction, the molar ratio of the amount of use to the polyacrylamide in the micro-crosslinking non-ionic polyacrylamide solution is 0.1, the pH is adjusted to weakly acidic 6-7, and drum drying is performed, to obtain a modified amphoteric polyacrylamide high-temperature filtrate reducer. Example 2

[0027] After the micro-crosslinking non-ionic polyacrylamide solution is cooled to 25°C room temperature, ice water bath to 0°C, then add KOH solution, KClO solution, control the molar ratio of -CONH2, OH-, ClO- in the reaction system is 1:0.8:0.4, sealed and continue to ice water bath 20 min, then restore to 25°C naturally, in this warming process, Hofmann degradation reaction occurs; during the Hofmann degradation reaction, sulfonated-3-phenoxy-2-hydroxypropyl trimethyl ammonium chloride formaldehyde resin is added, the molar ratio of which to the polyacrylamide in the micro-crosslinking non-ionic polyacrylamide solution is 0.3, the pH is adjusted to weak acidity 6-7, and drum drying is performed to obtain the modified amphoteric polyacrylamide high-temperature fluid loss additive. Example 3

[0028] After the micro-crosslinking non-ionic polyacrylamide solution is cooled to 25°C room temperature, ice water bath to 0°C, then add KOH solution, KClO solution, control the molar ratio of -CONH2, OH-, ClO- in the reaction system is 1:1:0.5, sealed and continue to ice water bath 20 min, then restore to 25°C naturally, in this warming process, Hofmann degradation reaction occurs; during the Hofmann degradation reaction, sulfonated-3-phenoxy-2-hydroxypropyl trimethyl ammonium chloride formaldehyde resin is added, the molar ratio of which to the polyacrylamide in the micro-crosslinking non-ionic polyacrylamide solution is 0.4, the pH is adjusted to weak acidity 6-7, and drum drying is performed to obtain the modified amphoteric polyacrylamide high-temperature fluid loss additive.

[0029] Comparative Example 1

[0030] After the micro-crosslinking non-ionic polyacrylamide solution is cooled to 25°C room temperature, ice water bath to 0°C, then add KOH solution, KClO solution, control the molar ratio of -CONH2, OH-, ClO- in the reaction system is 1:1:0.5, sealed and continue to ice water bath 20 min, then restore to 25°C naturally, in this warming process, Hofmann degradation reaction occurs; during the Hofmann degradation reaction, sulfonated-3-phenoxy-2-hydroxypropyl trimethyl ammonium chloride formaldehyde resin is added, the molar ratio of which to the polyacrylamide in the micro-crosslinking non-ionic polyacrylamide solution is 0.4, the pH is adjusted to weak acidity 6-7, and drum drying is performed to obtain the modified amphoteric polyacrylamide high-temperature fluid loss additive.

[0031] Comparative Example 2

[0032] After the micro-crosslinking non-ionic polyacrylamide solution is cooled to 25°C room temperature, ice water bath to 0°C, then add KOH solution, KClO solution, control the molar ratio of -CONH2, OH-, ClO- in the reaction system is 1:1:0.5, sealed and continue to ice water bath 20 min, then restore to 25°C naturally, in this warming process, Hofmann degradation reaction occurs; during the Hofmann degradation reaction, sulfonated-3-phenoxy-2-hydroxypropyl trimethyl ammonium chloride formaldehyde resin is added, the molar ratio of which to the polyacrylamide in the micro-crosslinking non-ionic polyacrylamide solution is 0.4, the pH is adjusted to weak acidity 6-7, and drum drying is performed to obtain the modified amphoteric polyacrylamide high-temperature fluid loss additive.

[0033] Comparative Example 3

[0034] After the micro-crosslinking non-ionic polyacrylamide solution is cooled to 25°C room temperature, an ice water bath is used to cool it to 0°C, then KOH solution and KClO solution are added, the molar ratio of -CONH2, OH-, and ClO- in the reaction system is controlled to be 1:1:0.5, the system is sealed and shaken, and then the ice water bath is continued for 20 minutes, and then the system is naturally restored to 25°C, during which the Hofmann degradation reaction occurs; during the Hofmann degradation reaction, 3-chloro-2-hydroxypropyl trimethylammonium chloride is added, the molar ratio of the amount of 3-chloro-2-hydroxypropyl trimethylammonium chloride to the polyacrylamide in the micro-crosslinking non-ionic polyacrylamide solution is 0.4, the pH is adjusted to weakly acidic 6-7, and then drum drying is performed to obtain the modified amphoteric polyacrylamide high-temperature fluid loss additive.

[0035] The performance of the above examples and comparative examples is evaluated, and the performance evaluation method is as follows:

[0036] 1. Preparation of drilling fluid base paste:

[0037] Fresh water base paste: prepared according to the standard SY / T 5060-93, 40 g of bentonite and 3 g of sodium carbonate are added to 1 L of fresh water, high-speed stirring is performed for 20 min, and the system is maintained at room temperature for 24 h;

[0038] Salt water base paste: a certain amount of NaCl is added to the above fresh water base paste, high-speed stirring is performed for 20 min, a salt water paste with a mass fraction of 7.0% of NaCl is prepared, and the system is maintained at room temperature for 24 h.

[0039] 2. Fluid loss performance evaluation:

[0040] According to the American Petroleum Institute (API) standard and the Chinese Petroleum and Natural Gas Industry Standard SY / T 524191 “Evaluation Procedure for Fluid Loss Additives for Water-Based Drilling Fluids”, the fluid loss additive is added to the fresh water or salt water base paste, high-speed stirring is performed for 15 min, the system is maintained at room temperature and 180°C for 16 h, respectively, and the drilling fluid fluid loss (FL) is measured.

[0041] 3. Inhibition evaluation:

[0042] The shale rolling recovery experiment is used to evaluate the inhibition performance of the modified amphoteric polyacrylamide fluid loss additive. The experimental steps are as follows: 3-5 mm of rock cuttings are added to the sample (350 mL of drilling fluid) of the modified amphoteric polyacrylamide (1% by mass) of different examples, the system is aged at 120°C for 16 h, the system is passed through a 0.154 mm sample separation sieve, and then the system is washed and dried to constant weight, the ratio of the final mass to the initial mass is the first recovery rate (R1); the recovered rock cuttings are placed in clean water again, the system is aged at 120°C for 2 h, the system is passed through a 0.154 mm sample separation sieve, and then the system is dried to constant weight, and the ratio of the final mass to the initial mass is the second recovery rate (R2).

[0043] The performance test results are as follows:

[0044] 1. Filtration reduction performance:

[0045] The modified amphoteric polyacrylamide products with different functional groups prepared in the examples are selected, and the mass fraction of 1.5% and 3% is added into the fresh water base slurry and the salt water base slurry respectively according to SY / T 524191 "Evaluation Procedure for Filtration Reducer for Water Base Drilling Fluids", and the filtration loss (FL) is measured. The results are shown in the following table.

[0046]

[0047] As can be seen from the table, the filtration reduction performance of the polymers with different functional groups is different, and the filtration reduction performance of the filtration reducer with sulfonated-3-phenoxy-2-hydroxypropyl trimethyl ammonium chloride formaldehyde resin is the best.

[0048] 2. Inhibition performance:

[0049] The shale rolling recovery experiment is mainly used for evaluating the shale inhibition of the drilling fluid treatment agent, and is a relatively simple method for quantitatively evaluating the hydration dispersion trend of shale. The core recovery rate (R1, R2) and the relative core recovery rate (R*) are shown in the following table.

[0050]

[0051] As can be seen from the table, the modified amphoteric polyacrylamide drilling fluid system has obviously high rolling recovery rates R1 and R2, which indicates that the modified amphoteric polyacrylamide is a strong inhibition type filtration reducer. This is because: the cations in the modified amphoteric polyacrylamide can be adsorbed on the surface of the cuttings through electrostatic action, and the cations can also enter the interlayer of the cuttings through ion exchange action, thereby showing excellent inhibition; in addition, the hydrophobic group of the surface adsorbed cation forms a hydrophobic layer, which prevents water molecules from entering the inside of the cuttings particles, and the interlayer adsorbed cation shortens the layer spacing through electrostatic action, effectively inhibiting the hydration and dispersion of the cuttings; in addition, the modified amphoteric polyacrylamide filtration reducer contains K + , which can prevent the hydration and peeling of soft shale and hard brittle shale, and achieve the effect of stabilizing the borehole wall. At the same time, the positive charge of the cation can neutralize the negative charge on the surface of the cuttings, thereby weakening the electrostatic repulsion between the cuttings particles, thereby inhibiting the hydration and dispersion of the cuttings.

Claims

1. A modified amphoteric polyacrylamide fluid loss additive characterized in that, The preparation method comprises the following steps: 100 parts of acrylamide and 4 parts of crosslinking agent N,N-methylene bisacrylamide are dissolved in 400 parts of deionized water according to the mass ratio, and a monomer solution with a concentration of 25% is obtained; after vacuum degassing of the monomer solution, 5 parts of a molecular weight regulator, sodium methallyl sulfonate, 12 parts of sodium pyrosulfite and 15 parts of sodium persulfate are added, the pH value is adjusted to 7.0, the temperature is adjusted to 45 DEG C, nitrogen is filled, and the reaction is started for 60 min; the temperature is adjusted to 65 DEG C; the reaction is continued for 2.5 h, 0.5% of a polymer mass of a treating agent, sodium bisulfite, is added, and aging is continued for 30 min, so that a micro-crosslinked non-ionic polyacrylamide solution is obtained; the micro-crosslinked non-ionic polyacrylamide solution is cooled to 25 DEG C, and then an ice water bath is used to cool the solution to 0 DEG C; then, KOH solution and KClO solution are added, the molar ratio of -CONH2, OH- and ClO- in the reaction system is controlled to be 1:1:0.5, the system is sealed and shaken, and ice water bath is continued for 20 min, and then the system is naturally recovered to 25 DEG C; in the process of temperature rising, Hofmann degradation reaction occurs; sulfonated-3-phenoxy-2-hydroxypropyl trimethylammonium chloride phenolic resin is added in the process of Hofmann degradation reaction, the molar ratio of the amount of the sulfonated-3-phenoxy-2-hydroxypropyl trimethylammonium chloride phenolic resin to the polyacrylamide in the micro-crosslinked non-ionic polyacrylamide solution is 0.4, the pH value is adjusted to weak acidity of 6-7, and drum drying is carried out, so that modified amphoteric polyacrylamide high-temperature filtration reducer is obtained.

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