Polyacrylamide coating agent for water-based drilling fluid and preparation method of polyacrylamide coating agent

Abstract

The invention belongs to the technical field of oil field drilling, and particularly relates to a polyacrylamide coating agent for water-based drilling fluid and a preparation method of the polyacrylamide coating agent, and the polyacrylamide coating agent is prepared by adopting an initiator to initiate free radical polymerization reaction of acrylamide, a modifier and a monomer II, the structure of the modifier contains a large number of unsaturated alkenyl substituent groups and a large number of sulfonic acid groups, so that the prepared polyacrylamide molecular chain can present a cross-linked structure, and the high temperature resistance and salt resistance of the coating agent are further improved; the clay mineral particles with negative electricity can generate a strong electrostatic adsorption effect, and a large number of hydrophilic ether bonds in the structure can generate good compatibility with hydrophilic clay minerals, so that the clay mineral particles can be highly wrapped with the hydrophilic ether bonds, and rock debris dispersion is effectively inhibited.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of oil field drilling, and particularly relates to a polyacrylamide coating agent for water-based drilling fluid and a preparation method thereof. BACKGROUND

[0002] Drilling fluid coating inhibitor is a core chemical treatment agent for stabilizing well wall and inhibiting stratum hydration expansion in oil and gas drilling. It forms a protective layer on the surface of drilling cuttings to prevent clay minerals from contacting with water molecules, thereby maintaining the stability of drilling fluid performance. As one of the most commonly used coating inhibitors, polyacrylamide (PAM) occupies a dominant position in land and shallow sea drilling due to its adjustable molecular structure and diverse functions. At present, as conventional oil and gas development gradually expands to deep layers, the filtration loss of drilling fluid is large in deep well and ultra-deep well drilling due to high stratum temperature and high salinity, and therefore, the temperature resistance and coating inhibition performance of the coating inhibitor are required to be particularly strict.

[0003] At present, the modification of polyacrylamide coating inhibitors is mainly through the design of the structure thereof. For example, the polyacrylamide coating agent prepared by selecting polymerization monomers can exhibit good temperature resistance according to the patent application No. CN201410184206.4, and therefore, the functionality of the polyacrylamide can be enhanced by adjusting the structure thereof, so that the polyacrylamide can meet the use requirements in deep well environment. SUMMARY

[0004] In view of the deficiencies of the prior art, the purpose of the present application is to provide a polyacrylamide coating agent for water-based drilling fluid and a preparation method thereof.

[0005] In the first aspect of the present application, a polyacrylamide coating agent for water-based drilling fluid is provided, which is prepared from the following raw materials by weight: acrylamide 50-65 parts, modifier 0.5-1.5 parts, monomer two 1-3 parts, initiator 0.1-0.2 parts, and deionized water 80-100 parts; The modifier is prepared from exo-3,6-epoxy-1,2,3,6-tetrahydrophthalic anhydride and N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid through reaction; The monomer two is prepared by first modifying 4-hydroxybutyl vinyl polyoxyethylene ether by carboxylation, and then reacting the obtained product with dodecyl bis-hydroxyethyl methyl ammonium chloride.

[0006] As a preferred technical solution of the present application, the modifier is prepared by the following method: The ex-3,6-epoxy-1,2,3,6-tetrahydrophthalic anhydride and dimethyl sulfoxide are added into a polymerization kettle, mixed uniformly by mechanical stirring, then nitrogen is introduced for protection, N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid is continuously added into the polymerization kettle, after addition, stirring is continued at a temperature of 30-40℃ for 2-4h, then a catalyst is added into the polymerization kettle, and the temperature is increased to 80-90℃ at a temperature increasing rate of 2-3℃ / min, after continuous heat preservation stirring for 12-16h, nitrogen is removed, the solvent is evaporated and removed, the product is collected, and after washing and vacuum drying treatment, the modifier is obtained.

[0007] As a preferred technical scheme of the present application, the molar ratio of the ex-3,6-epoxy-1,2,3,6-tetrahydrophthalic anhydride and N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid is 1:1.01-1.02.

[0008] As a preferred technical scheme of the present application, the catalyst is p-toluenesulfonic acid or sulfamic acid.

[0009] It should be noted that in the above technical scheme, the ex-3,6-epoxy-1,2,3,6-tetrahydrophthalic anhydride and N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid are used as raw materials, the anhydride group and active hydroxyl substituent in the structures of each other can undergo ring-opening esterification to obtain an intermediate containing active hydroxyl and active carboxyl groups in the structure, and then under the action of a catalyst and high temperature, the intermediate undergoes self-condensation reaction to prepare the modifier.

[0010] As a preferred technical scheme of the present application, the monomer two is prepared by the following method: Step S1, 4-hydroxybutyl vinyl polyoxyethylene ether is added into acetone, uniformly mixed by mechanical stirring, then a carboxylation reagent is added into the formed uniform solution, after addition, heat preservation stirring is continued at a temperature of 30-40℃ for 3-6h, heating is stopped, the solvent is evaporated and removed, and the temperature is lowered to discharge, to obtain an intermediate material; Step S2, the intermediate material is added into isopropyl alcohol, after uniform stirring, a composite catalyst is added, stirring is continued at room temperature for 2-4h, then dodecyl bis-hydroxyethyl methyl ammonium chloride is added, after addition, stirring is continued for 4-8h, the solvent is evaporated and removed, the temperature is lowered to discharge, and the product is collected to obtain the monomer two.

[0011] As a preferred technical scheme of the present application, in step S1, the number average molecular weight of the 4-hydroxybutyl vinyl polyoxyethylene ether is 2000-3000.

[0012] As a preferred technical scheme of the present application, in step S1, the carboxylation reagent is succinic anhydride or glutaric anhydride.

[0013] As a preferred technical scheme of the present application, in step S2, the composite catalyst is a mixture of dicyclohexyl carbodiimide and 4-dimethylamino pyridine, with a mass ratio of 1:0.2-0.3.

[0014] In the above technical scheme, first, the carboxyl group of 4-hydroxybutyl vinyl polyoxyethylene ether is modified by using a carboxylating agent to obtain a polyoxyethylene ether derivative containing active carboxyl substituents, i.e., an intermediate material; then, the carboxyl group of the intermediate material is activated by using a composite catalyst, and then esterification and condensation are performed with the hydroxyl group in the structure of dodecyl bis-hydroxyethyl methyl ammonium chloride to obtain monomer II.

[0015] As a preferred technical scheme of the present application, the initiator is any one of azobisdimethyl isobutyl cyanide, azobisdimethyl isohexyl cyanide, azobisdimethyl isobutyl amidine hydrochloride or azobisdimethyl isobutyl imidazole hydrochloride.

[0016] In a second aspect of the present application, a preparation method of a polyacrylamide coating agent for a water-based drilling fluid is provided, including the following steps: In a first step, acrylamide and monomer II are added to deionized water, and after uniform stirring, the temperature is increased to 70-75 DEG C, and two-thirds of the initiator is added, and after addition, the temperature is maintained for 2-4 h to form a prepolymer; In a second step, the modifier and the remaining amount of initiator are added to the prepolymer, the temperature is further increased to 80-82 DEG C, and the temperature is maintained for 6-12 h, heating is stopped, and the product is separated after cooling and discharging.

[0017] Compared with the prior art, the present application has the following beneficial effects: (1) The modifier prepared in the present application has a large number of unsaturated alkyl substituents in the structure, which can make the molecular chain of the prepared polyacrylamide exhibit a crosslinked structure, and the increase in the density of the molecular chain will cause the movement of the molecular chain to be hindered, thereby improving the high-temperature resistance of the coating agent. Meanwhile, the structure of the modifier also contains a rigid ring, which can further improve the thermal stability of the coating agent, thereby effectively improving the high-temperature resistance of the polyacrylamide coating agent. Meanwhile, the structure of the modifier also contains a large number of sulfonic acid groups, and the presence of the sulfonic acid groups can improve the sensitivity of the polyacrylamide to mineral salts, so that the coating agent can maintain high stability under high salinity conditions and exhibit excellent salt resistance.

[0018] (2) The quaternary ammonium cation group in the structure of the monomer II prepared in the present application can produce a strong electrostatic adsorption effect with clay mineral particles carrying negative electricity, and a large number of hydrophilic ether bonds in the structure can produce good compatibility with hydrophilic clay minerals, so that the clay mineral particles can be highly wrapped on the surface of the clay mineral particles, thereby effectively inhibiting the dispersion of the cuttings. BRIEF DESCRIPTION OF DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the description of the embodiments. Obviously, the drawings in the following description only show some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort based on these drawings.

[0020] Figure 1 The infrared analysis test chart of the modifier; Figure 2 The infrared analysis test chart of the monomer two. DETAILED DESCRIPTION

[0021] In order to facilitate the understanding of the present application, the present application lists the following embodiments. It should be obvious to those skilled in the art that the embodiments are only used to help understand the present application, and should not be regarded as a specific limitation on the present application.

[0022] The following method is used to prepare the modifier in the following examples and comparative examples: 0.2 g of exo-3,6-epoxy-1,2,3,6-tetrahydrophthalic anhydride and dimethyl sulfoxide are added to a polymerization kettle, and after being uniformly mixed by mechanical stirring, nitrogen is introduced for protection, 0.26 g of N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid is continuously added to the polymerization kettle, after addition, stirring is carried out at a temperature of 35℃ for 3 h, then 0.01 g of p-toluenesulfonic acid is added to the polymerization kettle, and the temperature is increased to 90℃ at a temperature increase rate of 2℃ / min, and after continuous incubation and stirring for 16 h, the nitrogen is removed, the solvent is evaporated and removed, the product is collected, and after washing and vacuum drying treatment, the modifier is obtained.

[0023] The preparation principle of the modifier is as follows:

[0024] Figure 1 The infrared analysis test chart of the modifier, in which the characteristic absorption peaks appearing at 3376 cm -1 and 3291 cm -1 are characteristic absorption peaks of hydroxyl groups, the characteristic absorption peak appearing at 3043 cm -1 is a C-H characteristic absorption peak of an unsaturated carbon-carbon double bond, the characteristic absorption peaks appearing at 1786 cm -1 and 1706 cm -1 are C=O characteristic absorption peaks of ester groups and carboxyl groups, the characteristic absorption peak appearing at 1592 cm -1 is a C-N characteristic absorption peak, and the characteristic absorption peak appearing at 917 cm -1 is a characteristic absorption peak of an epoxy group.

[0025] The monomer two in the following examples and comparative examples is prepared by the following method: Step S1, 1.2g of 4-hydroxybutyl vinyl polyoxyethylene ether with a number average molecular weight of 2000 is added to acetone, mechanically stirred and mixed uniformly, then 0.06g of succinic anhydride is added to the formed uniform solution, after addition, continuous incubation stirring at a temperature condition of 35℃ for 4h, stop heating, evaporate to remove the solvent, cool down and discharge, to obtain an intermediate material; Step S2, 0.8g of the intermediate material is added to isopropyl alcohol, after stirring and mixing uniformly, 0.1g of dicyclohexyl carbodiimide and 0.03g of 4-dimethylamino pyridine are added, stirring at room temperature for 3h, then 0.15g of dodecyl bis-hydroxyethyl methyl ammonium chloride is added, after addition, continue stirring for 6h, evaporate to remove the solvent, cool down and discharge, collect the product, to obtain the monomer two.

[0026] Figure 2 The infrared analysis test chart of the monomer two is shown in the figure, the characteristic absorption peak appearing at 3076cm -1 is the C-H characteristic absorption peak of unsaturated carbon-carbon double bond, the characteristic absorption peak appearing at 2800~3000cm -1 is the C-H characteristic absorption peak in the saturated aliphatic chain, the characteristic absorption peak appearing at 1728cm -1 is the C=O characteristic absorption peak of ester group, the characteristic absorption peak appearing at 1461cm -1 is the C-N characteristic absorption peak of quaternary ammonium salt, the characteristic absorption peak appearing at 1098cm -1 is the C-O characteristic absorption peak of ether bond.

[0027] Example 1 The present example provides a polyacrylamide-based coating agent for water-based drilling fluid, which is made of raw materials including the following weight fractions: Acrylamide 50 parts, modifier 0.5 parts, monomer two 1 part, azobis isobutyronitrile 0.1 part, deionized water 8 parts.

[0028] The preparation method of the coating agent includes the following steps: First step, acrylamide and monomer two are added to deionized water, after stirring and mixing uniformly, the temperature is increased to 70℃, and two-thirds of the amount of initiator is added, after addition, continuous incubation stirring for 2h, to form a prepolymer; Second step, the modifier and the remaining amount of initiator are added to the prepolymer, the temperature is further increased to 80℃, continuous incubation stirring for 6h, stop heating, cool down and discharge, separate the product, and purify.

[0029] Example 2 The present example provides a polyacrylamide-based coating agent for water-based drilling fluid, which is made of raw materials including the following weight fractions: Acrylamide 55 parts, modifier 1.2 parts, monomer two 2.5 parts, azobisisobutyronitrile 0.2 parts, deionized water 90 parts.

[0030] The preparation method of the coating agent comprises the following steps: Firstly, acrylamide and monomer two are added to deionized water, and after uniform stirring, the temperature is increased to 75℃, and two-thirds of the initiator is added, and after addition, the temperature is continuously stirred for 3h, and a prepolymer is formed; Secondly, the modifier and the remaining amount of initiator are added to the prepolymer, the temperature is further increased to 82℃, and the temperature is continuously stirred for 9h, the heating is stopped, the temperature is lowered to discharge, the product is separated, and after purification treatment, it is ready.

[0031] Example 3 The embodiment provides a polyacrylamide coating agent for water-based drilling fluid, which is made from raw materials including the following weight fractions: Acrylamide 65 parts, modifier 1.5 parts, monomer two 3 parts, azobisisobutyronitrile 0.2 parts, deionized water 100 parts.

[0032] The preparation method of the coating agent comprises the following steps: Firstly, acrylamide and monomer two are added to deionized water, and after uniform stirring, the temperature is increased to 75℃, and two-thirds of the initiator is added, and after addition, the temperature is continuously stirred for 3h, and a prepolymer is formed; Secondly, the modifier and the remaining amount of initiator are added to the prepolymer, the temperature is further increased to 82℃, and the temperature is continuously stirred for 9h, the heating is stopped, the temperature is lowered to discharge, the product is separated, and after purification treatment, it is ready.

[0033] Comparative Example 1 The comparative example provides a polyacrylamide coating agent for water-based drilling fluid, which is made from raw materials including the following weight fractions: Acrylamide 55 parts, modifier 1.2 parts, azobisisobutyronitrile 0.2 parts, deionized water 90 parts.

[0034] The preparation method of the coating agent comprises the following steps: Firstly, acrylamide is added to deionized water, and after uniform stirring, the temperature is increased to 75℃, and two-thirds of the azobisisobutyronitrile is added, and after addition, the temperature is continuously stirred for 3h, and a prepolymer is formed; Secondly, the modifier and the remaining amount of azobisisobutyronitrile are added to the prepolymer, the temperature is further increased to 82℃, and the temperature is continuously stirred for 9h, the heating is stopped, the temperature is lowered to discharge, the product is separated, and after purification treatment, it is ready.

[0035] Comparative Example 2 The embodiment provides a polyacrylamide coating agent for a water-based drilling fluid, which is prepared from raw materials in the following proportions by weight: 55 parts of acrylamide, 2.5 parts of monomer II, 0.2 parts of azobisdimethyl isobutyronitrile and 90 parts of deionized water.

[0036] The preparation method of the coating agent comprises the following steps: The acrylamide and the monomer II are added to the deionized water, and after uniform stirring, the temperature is increased to 75 DEG C, and the azobisdimethyl isobutyronitrile is added, and after the addition, the temperature is kept for 12 hours.

[0037] The coating agent provided in the above embodiment and the comparative example is subjected to performance testing, and the testing method is as follows: The coating agent is added to a 25% sodium chloride aqueous solution to prepare a 0.3% polymer solution, then 50g of shale rock debris with a mesh size of 10 is added to 300mL of the polymer solution, and after uniform dispersion, the mixture is subjected to hot rolling at a temperature of 200 DEG C for 16 hours, and after complete cooling, the rock debris is separated, and after complete drying, the weight is measured to calculate the rock debris recovery rate, and the test data are shown in Table 1.

[0038] Table 1-Test results

[0039] As known from the above, the coating agent prepared in the embodiment of the present application still has a high rock debris recovery rate under the conditions of high temperature and high salt. After the monomer II is removed, the adsorption effect of the coating agent on the clay mineral is weakened, and the rock debris recovery rate is poor. After the modifier is removed, the high-temperature resistance and salt resistance of the coating agent are weakened, and the rock debris recovery rate is obviously reduced.

[0040] The principles and implementation modes of the present application are described by using specific examples in the present application, and the above embodiment is only used to help understand the method and the core idea of the present application, including the best mode, and also enables any person skilled in the art to practice the present application, including manufacturing and using any device or system, and implementing any combined method. It should be noted that, for those skilled in the art, some improvements and modifications can be made to the present application without departing from the principles of the present application, and these improvements and modifications also fall within the protection scope of the present application.

Claims

1. A polyacrylamide-based coating agent for a water-based drilling fluid, characterized by comprising a polyacrylamide-based copolymer and a cationic surfactant. The raw materials including the following weight parts are used to prepare the application: 50-65 parts of acrylamide, 0.5-1.5 parts of modifier, 1-3 parts of monomer two, 0.1-0.2 parts of initiator, 80-100 parts of deionized water; The modifier is prepared by reaction with exo-3,6-epoxy-1,2,3,6-tetrahydrophthalic anhydride and N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid as raw materials; The monomer two is prepared by first modifying 4-hydroxybutyl vinyl polyoxyethylene ether by carboxylation, and then further reacting the obtained product with dodecyl bis-hydroxyethyl methyl ammonium chloride; The initiator is any one of azobisdimethyl isobutyl cyanide, azobisdimethyl isopentyl cyanide, azobisdimethyl isobutyl amidine hydrochloride or azobisdimethyl isobutyl imidazole hydrochloride.

2. The polyacrylamide-based coating agent for a water-based drilling fluid according to claim 1, characterized by, The modifier is prepared by the following method: exo-3,6-epoxy-1,2,3,6-tetrahydrophthalic anhydride and dimethyl sulfoxide are added to a polymerization kettle, mechanically stirred and mixed uniformly, then nitrogen is introduced for protection, N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid is further added to the polymerization kettle, after addition, stirring is continued at a temperature of 30-40℃ for 2-4h, then a catalyst is added to the polymerization kettle, and the temperature is raised to 80-90℃ at a rate of 2-3℃ / min, after continuous heat preservation and stirring for 12-16h, the nitrogen is removed, the solvent is evaporated and removed, the product is collected, washed, and vacuum dried to obtain the modifier; The catalyst is p-toluenesulfonic acid or amino sulfonic acid.

3. The polyacrylamide-based coating agent for a water-based drilling fluid according to claim 2, characterized by, The molar ratio of exo-3,6-epoxy-1,2,3,6-tetrahydrophthalic anhydride and N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid is 1:1.01-1.

02.

4. The polyacrylamide-based coating agent for a water-based drilling fluid according to claim 1, characterized by, The monomer two is prepared by the following method: Step S1, 4-hydroxybutyl vinyl polyoxyethylene ether is added to acetone, mechanically stirred and mixed uniformly, then a carboxylation reagent is added to the formed uniform solution, after addition, heat preservation and stirring is continued at a temperature of 30-40℃ for 3-6h, heating is stopped, the solvent is evaporated and removed, and the temperature is lowered to discharge the material, to obtain an intermediate material; The carboxylation reagent is succinic anhydride or glutaric anhydride; Step S2, the intermediate material is added to isopropyl alcohol, stirred and mixed uniformly, then a composite catalyst is added, stirring is continued at room temperature for 2-4h, then dodecyl bis-hydroxyethyl methyl ammonium chloride is added, after addition, stirring is continued for 4-8h, the solvent is evaporated and removed, the temperature is lowered to discharge the material, and the product is collected to obtain the monomer two; The composite catalyst is a mixture of dicyclohexyl carbodiimide and 4-dimethylamino pyridine, with a mass ratio of 1:0.2-0.

3.

5. The polyacrylamide-based coating agent for a water-based drilling fluid according to claim 4, characterized by, In step S1, the number average molecular weight of the 4-hydroxybutyl vinyl polyoxyethylene ether is 2000-3000.

6. A method for preparing the polyacrylamide-based coating agent for a water-based drilling fluid according to claim 1, characterized by, The following steps are included: First step, acrylamide and monomer two are added to deionized water, stirred and mixed uniformly, then the temperature is raised to 70-75℃, and two-thirds of the amount of initiator is added, after addition, heat preservation and stirring is continued for 2-4h to form a prepolymer material; Second step, the modifier and the remaining amount of initiator into the prepolymer, the temperature is further increased to 80-82 ℃, continue to keep warm stirring 6-12 h, stop heating, cooling discharge, separation of the product, purification treatment, can.

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