Preparation method of environment-friendly salt-resistant and high-temperature-resistant filtrate reducer for long open hole section

Abstract

The invention discloses a preparation method of an environment-friendly salt-resistant and high-temperature-resistant filtrate reducer for a long open hole section. The preparation method specifically comprises the following steps: step 1, preparing a first mixed solution; step 2, preparing dispersion liquid; step 3, mixing the first mixed solution and the dispersion solution, and then shearing for 1-2 hours to obtain a shearing solution; step 4, adding the shear fluid into a reaction kettle, introducing nitrogen into the reaction kettle, discharging air in the reaction kettle, keeping the temperature at 70 DEG C, stirring for 10 minutes while keeping the temperature, adding an initiator, and stirring for 10-12 hours to obtain a reaction liquid; step 5, adding the reaction liquid into isopropanol according to a volume ratio of 1: 1.5, stirring for 40 minutes, standing for 2 hours, and filtering to obtain a reaction material; and step 6, washing the reaction material with absolute ethyl alcohol and methanol for 10 minutes respectively, and then drying to obtain the environment-friendly salt-resistant and high-temperature-resistant filtrate reducer for the long open hole section. The problem that an existing filtrate loss agent is poor in filtrate loss reduction performance in a long open hole section is solved.

Description

Preparation method of environmentally friendly salt-resistant and high-temperature resistant filtration loss reducing agent for long naked eye segment Technical Field

[0001] This invention belongs to the technical field of filtration loss reduction agent preparation methods, and relates to a preparation method of an environmentally friendly, salt-resistant, and high-temperature resistant filtration loss reduction agent for use in the long naked eye segment. Background Technology

[0002] In oil drilling engineering, the long open-hole section indeed refers to the length of the well section without casing protection during the drilling process. This section of the wellbore is directly exposed to the underground rock formations, and therefore faces various complex geological conditions, including but not limited to formation pressure, fluid intrusion, and rock stability challenges. Because it is not protected by casing, the wellbore in the long open-hole section is in direct contact with the underground rock formations, and its stability and safety are crucial to the success of the entire drilling project. The performance of the drilling fluid directly affects the cleanliness of the wellbore and the stability of the wellbore. Selecting a drilling fluid with good stability and inhibition properties to improve wellbore stability and prevent fluid intrusion has a direct impact on the drilling project. The long open-hole section is a critical and complex stage in oil drilling engineering, and the drilling fluid is the working fluid in the oil drilling process. Its performance has a significant impact on the drilling of long open-hole sections. Filtration and wall-building properties are one of the most basic properties of drilling fluids, and the main factor affecting filtration and wall-building properties is the quality of the drilling fluid filter cake.

[0003] When existing drilling fluids are used under high temperature and high salinity conditions, the hydration effect of the filtration reducer in the drilling fluid is greatly weakened, resulting in reduced solubility. Consequently, the adsorption effect on the surface of clay particles is significantly reduced, while the dehydration effect on the surface of clay particles is enhanced. The hydration layer on the surface of clay particles becomes thinner, leading to a decrease in the bound water content of the mud cake and a reduction in the compressibility of the mud cake. Ultimately, this results in poor mud cake compaction, increased filtration loss, and deterioration of the drilling fluid's wall-building properties, affecting the normal progress of drilling operations.

[0004] Therefore, the present invention solves the corresponding problems by providing a method for preparing an environmentally friendly, salt-resistant, high-temperature resistant filtration loss reducing agent for use in the long naked eye segment. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing an environmentally friendly, salt-resistant, and high-temperature resistant filtration loss reducing agent for use in the long naked eye segment, which solves the problem of poor filtration loss reduction performance of existing filtration loss reducing agents in the long naked eye segment.

[0006] The technical solution adopted in this invention is a preparation method of an environmentally friendly, salt-resistant, high-temperature-resistant filtration-reducing agent for long naked-eye segments, specifically implemented according to the following steps: Step 1, preparing a first mixture; Step 2, preparing carbon-nitrogen nanocomposite particles, modifying them to obtain modified carbon-nitrogen nanoparticles, adding octadecyl dimethyl allyl ammonium chloride and modified carbon-nitrogen nanoparticles sequentially to xylene, and dispersing by ultrasonication to obtain a dispersion; Step 3, mixing the first mixture and the dispersion, and then shearing for 1-2 hours to obtain a shearing fluid; mixing the first mixture and the dispersion... The volume ratio is 1:1; Step 4, add the shearing fluid to the reactor, introduce nitrogen into the reactor to purge the air inside, maintain the temperature at 70℃, stir for 10 minutes, then add the initiator and stir for 10-12 hours to obtain the reaction solution; Step 5, add the reaction solution to isopropanol at a volume ratio of 1:1.5, stir for 40 minutes, let stand for 2 hours, filter, and obtain the reaction material; Step 6, wash the reaction material with anhydrous ethanol and methanol for 10 minutes each, and then dry it to obtain an environmentally friendly salt-resistant and high-temperature filtration loss reducing agent for long naked eye segments.

[0007] The technical solution of the present invention is further characterized in that step 1 is specifically as follows: Step 1.1, acrylamide and 2-acrylamide-2-methylpropanesulfonic acid are added to deionized water in sequence and stirred and mixed evenly to obtain a composite solution; Step 1.2, the pH of the composite solution is adjusted to 8.3, and then Tween-80 is added and stirred and mixed again to obtain a first mixture.

[0008] In step 1.1, the molar ratio of acrylamide to 2-acrylamide-2-methylpropanesulfonic acid is 3:1; the mass ratio of acrylamide to deionized water is 1-1.5:6.

[0009] In step 1.2, the pH of the composite solution is adjusted by using sodium hydroxide solution with a mass fraction of 10%, and the amount of Tween-80 added is 5-6% of the mass of the composite solution.

[0010] Step 2 specifically involves: Step 2.1, the preparation method of carbon-nitrogen nanocomposite particles is as follows: Melamine is added to methanol and dissolved by stirring to obtain a melamine-methanol solution; nano-silica is added to the melamine-methanol solution and dispersed by ultrasonication to obtain a composite dispersion; the composite dispersion is dried by rotary evaporation to obtain a composite material; the composite material is placed in a tube furnace and heated to 580-600℃ in an air atmosphere, held for 2 hours, and then cooled to room temperature to obtain carbon-nitrogen nanocomposite particles; wherein, the mixing ratio of melamine to methanol is 25. -30g:130mL; the mixing ratio of nano-silica to melamine methanol solution is 1-1.5g:130mL; the heating rate is 3℃ / min; step 2.2, the preparation method of modified carbon-nitrogen nanoparticles is as follows: prepare sulfuric acid solution; add carbon-nitrogen nanocomposite particles to sulfuric acid solution, disperse by ultrasonication to obtain a mixture; add the mixture dropwise to methanol while stirring, after the addition is complete, continue stirring for 30min, then let stand for 2 hours, then filter, wash with water until neutral, and vacuum dry to obtain modified carbon-nitrogen nanoparticles.

[0011] In step 2.2, the sulfuric acid solution has a mass fraction of 60%; the ratio of carbon-nitrogen nanocomposite particles to sulfuric acid solution is 18-20g:200mL; the volume ratio of the mixture to methanol is 1:2; and the vacuum drying temperature is 60℃ for 10 hours.

[0012] In step 2, the mixing ratio of octadecyl dimethyl allyl ammonium chloride, modified carbon-nitrogen nanoparticles, and xylene is 20-30g: 0.4-0.5g: 150mL.

[0013] In step 4, the initiator is azobisisobutyronitrile (AIBN), and the amount of AIBN added is 2-3% of the mass of the shear fluid.

[0014] The beneficial effects of this invention are as follows: by introducing the filtration loss reducer prepared by this invention into the drilling fluid, its apparent viscosity and dynamic shear force can be significantly increased. The increase in viscosity can effectively slow down the filtration loss rate of the drilling fluid into the formation, thereby reducing the filtration loss. Furthermore, after aging, the apparent viscosity is significantly improved, the dynamic shear force is also significantly improved, the overall rheological properties are greatly improved, the filtration loss is low, and the filtration performance is excellent.

[0015] By introducing the filtration loss reducer of this invention, the viscosity of the drilling fluid can be increased, which to a certain extent prevents water and solid particles in the drilling fluid from penetrating into the formation too quickly, thereby effectively maintaining the stability of the drilling fluid.

[0016] The filtration loss reducer prepared in this invention mainly adsorbs onto the surface of clay particles through interactions such as hydrogen bonds, thereby increasing the negative charge on the surface of the clay particles and thickening the hydration layer, thus improving the aggregation stability of the clay particles, enabling them to be uniformly dispersed and less prone to aggregation and precipitation.

[0017] Because of the adsorption characteristics of the filtration loss reducer prepared by this invention, it can be firmly adsorbed on the surface of clay particles and form a protective layer. The presence of the protective layer can effectively avoid the aggregation effect of viscous particles. The uniform dispersion of the surface layer helps to form a thin, tough, and dense filter cake. Through its special structural characteristics, it can effectively reduce the filtration loss of drilling fluid. The sufficient proportion of fine particles can also improve the rock-carrying capacity of drilling fluid. Furthermore, it can greatly improve the lubrication performance of drilling fluid, increase working efficiency, and reduce machine wear.

[0018] Due to the properties of the prepared filtration loss reducer, a certain amount of negatively charged groups can be dissociated in the drilling fluid. These negatively charged groups can then electrostatically attract clay particles in the drilling fluid. Thus, the uniform dispersion properties of the filtration loss reducer can promote the uniform dispersion of clay particles.

[0019] The filtration loss reducing agent prepared by this invention also has excellent salt resistance and high temperature resistance. When used in a high-salt environment, it can maintain excellent filtration loss reducing performance and also has high temperature stability. Attached Figure Description

[0020] Figure 1 shows the reduction in filtration loss of the environmentally friendly, salt-resistant, and high-temperature resistant filtration loss reducer for long naked eye use according to the preparation method of the present invention at different sodium chloride contents. Detailed Implementation

[0021] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0022] The present invention discloses a method for preparing an environmentally friendly, salt-resistant, high-temperature resistant filtration loss reducing agent for use in the long naked eye segment, which is specifically implemented according to the following steps: Step 1, preparing a first mixture, specifically: Step 1.1, adding acrylamide and 2-acrylamide-2-methylpropanesulfonic acid sequentially to deionized water, stirring and mixing evenly to obtain a composite solution; the molar ratio of acrylamide to 2-acrylamide-2-methylpropanesulfonic acid is 3:1; the mass ratio of acrylamide to deionized water is 1-1.5:6.

[0023] Step 1.2: Adjust the pH of the composite solution to 8.3, then add Tween-80 and continue stirring to obtain the first mixture; the pH of the composite solution is adjusted by using sodium hydroxide solution with a mass fraction of 10%, and the amount of Tween-80 added is 5-6% of the mass of the composite solution.

[0024] Step 2: Prepare carbon-nitrogen nanocomposite particles and modify them to obtain modified carbon-nitrogen nanoparticles. Octadecyldimethylallylammonium chloride and the modified carbon-nitrogen nanoparticles are sequentially added to xylene and dispersed by ultrasonication to obtain a dispersion. Specifically: Step 2.1, the preparation method of carbon-nitrogen nanocomposite particles is as follows: Melamine is added to methanol and dissolved by stirring to obtain a melamine-methanol solution; nano-silica is added to the melamine-methanol solution and dispersed by ultrasonication to obtain a composite dispersion; the composite dispersion is dried by rotary evaporation to obtain a composite material; the composite material is placed in a tube furnace and heated to 580-600℃ in an air atmosphere, held for 2 hours, and then cooled to room temperature to obtain carbon-nitrogen nanocomposite particles; wherein, the mixing ratio of melamine to methanol is 25-30g:130mL; the mixing ratio of nano-silica to melamine-methanol solution is 1-1.5g:130mL; the heating rate is 3℃ / min.

[0025] Step 2.2, the preparation method of modified carbon-nitrogen nanoparticles is as follows: Prepare a sulfuric acid solution; add carbon-nitrogen nanocomposite particles to the sulfuric acid solution, disperse by ultrasonication to obtain a mixture; add the mixture dropwise to methanol while stirring, and continue stirring for 30 minutes after the addition is complete, then let it stand for 2 hours, filter, wash with water until neutral, and vacuum dry to obtain modified carbon-nitrogen nanoparticles. The mass fraction of the sulfuric acid solution is 60%; the mixing ratio of carbon-nitrogen nanocomposite particles to sulfuric acid solution is 18-20 g: 200 mL; the volume ratio of the mixture to methanol is 1:2; the vacuum drying temperature is 60℃ and the time is 10 hours. In step 2, the mixing ratio of octadecyl dimethyl allyl ammonium chloride, modified carbon-nitrogen nanoparticles, and xylene is 20-30 g: 0.4-0.5 g: 150 mL.

[0026] Step 3: Mix the first mixture and the dispersion, and then shear for 1-2 hours to obtain the shearing liquid; the volume ratio of the first mixture and the dispersion is 1:1. Step 4: Add the shearing liquid to the reactor, introduce nitrogen into the reactor to purge the air inside, maintain the temperature at 70℃, stir for 10 minutes, then add the initiator and stir for 10-12 hours to obtain the reaction liquid; the initiator is azobisisobutyronitrile, and the amount of azobisisobutyronitrile added is 2-3% of the mass of the shearing liquid.

[0027] Step 5: Add the reaction solution to isopropanol at a volume ratio of 1:1.5, stir for 40 minutes, let stand for 2 hours, filter, and obtain the reaction material; Step 6: Wash the reaction material with anhydrous ethanol and methanol for 10 minutes respectively, and then dry it to obtain an environmentally friendly salt-resistant and high-temperature filtration loss reducing agent for long naked eye segments.

[0028] By introducing the filtration loss reducer prepared according to the present invention into the drilling fluid, its apparent viscosity and dynamic shear force can be significantly increased. The increase in viscosity can effectively slow down the filtration loss rate of the drilling fluid into the formation, thereby reducing the filtration loss. Furthermore, the apparent viscosity is significantly improved after aging, the dynamic shear force is also significantly improved, the overall rheology is greatly improved, the filtration loss is low, and the filtration performance is excellent.

[0029] By introducing the filtration loss reducer of this invention, the viscosity of the drilling fluid can be increased, which to a certain extent prevents water and solid particles in the drilling fluid from penetrating into the formation too quickly, thereby effectively maintaining the stability of the drilling fluid.

[0030] The filtration loss reducer prepared in this invention mainly adsorbs onto the surface of clay particles through interactions such as hydrogen bonds, thereby increasing the negative charge on the surface of the clay particles and thickening the hydration layer, thus improving the aggregation stability of the clay particles, enabling them to be uniformly dispersed and less prone to aggregation and precipitation.

[0031] Because of the adsorption characteristics of the filtration loss reducer prepared by this invention, it can be firmly adsorbed on the surface of clay particles and form a protective layer. The presence of the protective layer can effectively avoid the aggregation effect of viscous particles. The uniform dispersion of the surface layer helps to form a thin, tough, and dense filter cake. Through its special structural characteristics, it can effectively reduce the filtration loss of drilling fluid. The sufficient proportion of fine particles can also improve the rock-carrying capacity of drilling fluid. Furthermore, it can greatly improve the lubrication performance of drilling fluid, increase working efficiency, and reduce machine wear.

[0032] Due to the properties of the prepared filtration loss reducer, a certain amount of negatively charged groups can be dissociated in the drilling fluid. These negatively charged groups can then electrostatically attract clay particles in the drilling fluid. Thus, the uniform dispersion properties of the filtration loss reducer can promote the uniform dispersion of clay particles.

[0033] The filtration loss reducing agent prepared by this invention also has excellent salt resistance and high temperature resistance. When used in a high-salt environment, it can maintain excellent filtration loss reducing performance and also has high temperature stability.

[0034] Example 1: Preparation method of environmentally friendly salt-resistant and high-temperature resistant filtration loss reducing agent for long naked eye segment, including the following steps: Step 1, preparing the first mixture, specifically: adding acrylamide and 2-acrylamide-2-methylpropanesulfonic acid to deionized water in sequence, stirring and mixing evenly to obtain a composite solution; the molar ratio of acrylamide to 2-acrylamide-2-methylpropanesulfonic acid is 3:1; the mass ratio of acrylamide to deionized water is 1:6.

[0035] Step 1.2: Adjust the pH of the composite solution to 8.3, then add Tween-80 and continue stirring to obtain the first mixture; adjust the pH of the composite solution using sodium hydroxide solution; wherein, the mass fraction of sodium hydroxide solution is 10%; the amount of Tween-80 added is 5% of the mass of the composite solution.

[0036] Step 2: Prepare carbon-nitrogen nanocomposite particles and modify them to obtain modified carbon-nitrogen nanoparticles. Octadecyldimethylallylammonium chloride and the modified carbon-nitrogen nanoparticles are sequentially added to xylene and dispersed by ultrasonication to obtain a dispersion. Specifically: Step 2.1, the preparation method of carbon-nitrogen nanocomposite particles is as follows: Melamine is added to methanol and dissolved by stirring to obtain a melamine-methanol solution; nano-silica is added to the melamine-methanol solution and dispersed by ultrasonication to obtain a composite dispersion; the composite dispersion is dried by rotary evaporation to obtain a composite material; the composite material is placed in a tube furnace and heated to 580℃ in an air atmosphere, held for 2 hours, and then cooled to room temperature to obtain carbon-nitrogen nanocomposite particles; the mixing ratio of melamine and methanol is 25g:130mL; the mixing ratio of nano-silica and melamine-methanol solution is 1g:130mL; the heating rate is 3℃ / min.

[0037] Step 2.2, the preparation method of modified carbon and nitrogen nanoparticles is as follows: First, prepare a sulfuric acid solution; add carbon and nitrogen nanocomposite particles to the sulfuric acid solution, disperse by ultrasonication to obtain a mixture; add the mixture dropwise to methanol while stirring, and continue stirring for 30 minutes after the addition is complete, then let it stand for 2 hours, filter it, wash it with water until neutral, and dry it under vacuum to obtain modified carbon and nitrogen nanoparticles.

[0038] The sulfuric acid solution has a mass fraction of 60%.

[0039] The mixing ratio of carbon-nitrogen nanocomposite particles and sulfuric acid solution is 18g:200mL; the volume ratio of the mixture to methanol is 1:2.

[0040] The vacuum drying temperature is 60℃ and the time is 10 hours.

[0041] In step 2, the mixing ratio of octadecyl dimethyl allyl ammonium chloride, modified carbon-nitrogen nanoparticles, and xylene is 20g:0.4g:150mL.

[0042] Step 3: Mix the first mixture and the dispersion together, and then shear for 1 hour to obtain a shearing liquid; the volume ratio of the first mixture and the dispersion is 1:1. Step 4: Add the obtained shearing liquid to the reactor, then introduce nitrogen gas into the reactor to purge the air inside the reactor, adjust the temperature to 70°C, keep it at this temperature and stir for 10 minutes, then add the initiator and continue stirring for 10 hours to obtain a reaction liquid; the initiator is azobisisobutyronitrile; the amount of azobisisobutyronitrile added is 2% of the mass of the shearing liquid.

[0043] Step 5: Add the reaction solution to isopropanol at a volume ratio of 1:1.5, stir for 40 minutes, let stand for 2 hours, filter, and obtain the reaction material; Step 6: Wash the reaction material with anhydrous ethanol and methanol for 10 minutes respectively, and then dry it to obtain an environmentally friendly salt-resistant and high-temperature filtration loss reducing agent for long naked eye segments.

[0044] Example 2: Preparation method of environmentally friendly salt-resistant and high-temperature resistant filtration loss reducing agent for long naked eye segment, including the following steps: Step 1, acrylamide and 2-acrylamide-2-methylpropanesulfonic acid are added to deionized water in sequence and stirred and mixed evenly to obtain a composite solution; the molar ratio of acrylamide to 2-acrylamide-2-methylpropanesulfonic acid is 3:1; the mass ratio of acrylamide to deionized water is 1.2:6.

[0045] Step 1.2: Adjust the pH of the composite solution to 8.3, then add Tween-80 and continue stirring to obtain the first mixture; adjust the pH of the composite solution using sodium hydroxide solution; wherein, the mass fraction of sodium hydroxide solution is 10%; the amount of Tween-80 added is 5.5% of the mass of the composite solution.

[0046] Step 2: Prepare carbon-nitrogen nanocomposite particles and modify them to obtain modified carbon-nitrogen nanoparticles. Octadecyldimethylallylammonium chloride and modified carbon-nitrogen nanoparticles are added sequentially to xylene and dispersed by ultrasonication to obtain a dispersion. Specifically: Step 2.1, the preparation method of carbon-nitrogen nanocomposite particles is as follows: Melamine is added to methanol and dissolved by stirring to obtain a melamine-methanol solution; nano-silica is added to the melamine-methanol solution and dispersed by ultrasonication to obtain a composite dispersion; the composite dispersion is dried by rotary evaporation to obtain a composite material; the composite material is placed in a tube furnace and heated to 585℃ in an air atmosphere, held for 2 hours, and then cooled to room temperature to obtain carbon-nitrogen nanocomposite particles; the mixing ratio of melamine to methanol is 26g:130mL; the mixing ratio of nano-silica to melamine-methanol solution is 1.2g:130mL; the heating rate is 3℃ / min.

[0047] Step 2.2, the preparation method of modified carbon and nitrogen nanoparticles is as follows: First, prepare a sulfuric acid solution; add carbon and nitrogen nanocomposite particles to the sulfuric acid solution, disperse by ultrasonication to obtain a mixture; add the mixture dropwise to methanol while stirring, and continue stirring for 30 minutes after the addition is complete, then let it stand for 2 hours, filter it, wash it with water until neutral, and dry it under vacuum to obtain modified carbon and nitrogen nanoparticles.

[0048] The sulfuric acid solution has a mass fraction of 60%.

[0049] The mixing ratio of carbon-nitrogen nanocomposite particles and sulfuric acid solution is 19g:200mL; the volume ratio of the mixture to methanol is 1:2.

[0050] The vacuum drying temperature is 60℃ and the time is 10 hours.

[0051] In step 2, the mixing ratio of octadecyl dimethyl allyl ammonium chloride, modified carbon and nitrogen nanoparticles, and xylene is 22g:0.45g:150mL.

[0052] Step 3: Mix the first mixture and dispersion together, and then shear for 1.5 hours to obtain a shearing liquid; the volume ratio of the first mixture and dispersion is 1:1. Step 4: Add the obtained shearing liquid to the reactor, then introduce nitrogen gas into the reactor to purge the air inside the reactor, adjust the temperature to 70°C, keep it warm and stir for 10 minutes, then add the initiator and continue stirring for 11 hours to obtain a reaction liquid; the initiator is azobisisobutyronitrile; the amount of azobisisobutyronitrile added is 2.3% of the mass of the shearing liquid.

[0053] Step 5: Add the reaction solution to isopropanol at a volume ratio of 1:1.5, stir for 40 minutes, let stand for 2 hours, filter, and obtain the reaction material; Step 6: Wash the reaction material with anhydrous ethanol and methanol for 10 minutes respectively, and then dry it to obtain an environmentally friendly salt-resistant and high-temperature filtration loss reducing agent for long naked eye segments.

[0054] Example 3: Preparation method of environmentally friendly salt-resistant and high-temperature resistant filtration loss reducing agent for long naked eye segment, including the following steps: Step 1, acrylamide and 2-acrylamide-2-methylpropanesulfonic acid are added to deionized water in sequence and stirred and mixed evenly to obtain a composite solution; the molar ratio of acrylamide to 2-acrylamide-2-methylpropanesulfonic acid is 3:1; the mass ratio of acrylamide to deionized water is 1.3:6.

[0055] Step 1.2: Adjust the pH of the composite solution to 8.3, then add Tween-80 and continue stirring to obtain the first mixture; adjust the pH of the composite solution using sodium hydroxide solution; wherein, the mass fraction of sodium hydroxide solution is 10%; the amount of Tween-80 added is 5.5% of the mass of the composite solution.

[0056] Step 2: Prepare carbon-nitrogen nanocomposite particles and modify them to obtain modified carbon-nitrogen nanoparticles. Octadecyldimethylallylammonium chloride and modified carbon-nitrogen nanoparticles are sequentially added to xylene and dispersed by ultrasonication to obtain a dispersion. Specifically: Step 2.1, the preparation method of carbon-nitrogen nanocomposite particles is as follows: Melamine is added to methanol and dissolved by stirring to obtain a melamine-methanol solution; nano-silica is added to the melamine-methanol solution and dispersed by ultrasonication to obtain a composite dispersion; the composite dispersion is dried by rotary evaporation to obtain a composite material; the composite material is placed in a tube furnace and heated to 590℃ in an air atmosphere, held for 2 hours, and then cooled to room temperature to obtain carbon-nitrogen nanocomposite particles; the mixing ratio of melamine and methanol is 28g:130mL; the mixing ratio of nano-silica to melamine-methanol solution is 1.2g:130mL; the heating rate is 3℃ / min.

[0057] Step 2.2, the preparation method of modified carbon and nitrogen nanoparticles is as follows: First, prepare a sulfuric acid solution; add carbon and nitrogen nanocomposite particles to the sulfuric acid solution, disperse by ultrasonication to obtain a mixture; add the mixture dropwise to methanol while stirring, and continue stirring for 30 minutes after the addition is complete, then let it stand for 2 hours, filter it, wash it with water until neutral, and dry it under vacuum to obtain modified carbon and nitrogen nanoparticles.

[0058] The sulfuric acid solution has a mass fraction of 60%.

[0059] The mixing ratio of carbon-nitrogen nanocomposite particles and sulfuric acid solution is 19g:200mL; the volume ratio of the mixture to methanol is 1:2.

[0060] The vacuum drying temperature is 60℃ and the time is 10 hours.

[0061] In step 2, the mixing ratio of octadecyl dimethyl allyl ammonium chloride, modified carbon-nitrogen nanoparticles, and xylene is 24g:0.43g:150mL.

[0062] Step 3: Mix the first mixture and the dispersion together, and then shear for 1.5 hours to obtain the shearing liquid; the volume ratio of the first mixture and the dispersion is 1:1. Step 4: Add the obtained shearing liquid to the reactor, then introduce nitrogen gas into the reactor to purge the air inside the reactor, adjust the temperature to 70°C, keep it at this temperature and stir for 10 minutes, then add the initiator and continue stirring for 11 hours to obtain the reaction liquid; the initiator is azobisisobutyronitrile; the amount of azobisisobutyronitrile added is 2.6% of the mass of the shearing liquid.

[0063] Step 5: Add the reaction solution to isopropanol at a volume ratio of 1:1.5, stir for 40 minutes, let stand for 2 hours, filter, and obtain the reaction material; Step 6: Wash the reaction material with anhydrous ethanol and methanol for 10 minutes respectively, and then dry it to obtain an environmentally friendly salt-resistant and high-temperature filtration loss reducing agent for long naked eye segments.

[0064] Example 4: Preparation method of environmentally friendly salt-resistant and high-temperature resistant filtration loss reducing agent for long naked eye segment, including the following steps: Step 1: Acrylamide and 2-acrylamide-2-methylpropanesulfonic acid are added to deionized water in sequence and stirred and mixed evenly to obtain a composite solution; the molar ratio of acrylamide to 2-acrylamide-2-methylpropanesulfonic acid is 3:1; the mass ratio of acrylamide to deionized water is 1.2:6.

[0065] Step 1.2: Adjust the pH of the composite solution to 8.3, then add Tween-80 and continue stirring to obtain the first mixture; adjust the pH of the composite solution using sodium hydroxide solution; wherein, the mass fraction of sodium hydroxide solution is 10%; the amount of Tween-80 added is 5.8% of the mass of the composite solution.

[0066] Step 2: Prepare carbon-nitrogen nanocomposite particles and modify them to obtain modified carbon-nitrogen nanoparticles. Octadecyldimethylallylammonium chloride and modified carbon-nitrogen nanoparticles are sequentially added to xylene and dispersed by ultrasonication to obtain a dispersion. Specifically: Step 2.1, the preparation method of carbon-nitrogen nanocomposite particles is as follows: Melamine is added to methanol and dissolved by stirring to obtain a melamine-methanol solution; nano-silica is added to the melamine-methanol solution and dispersed by ultrasonication to obtain a composite dispersion; the composite dispersion is dried by rotary evaporation to obtain a composite material; the composite material is placed in a tube furnace and heated to 585℃ in an air atmosphere, held for 2 hours, and then cooled to room temperature to obtain carbon-nitrogen nanocomposite particles; the mixing ratio of melamine to methanol is 27g:130mL; the mixing ratio of nano-silica to melamine-methanol solution is 1.4g:130mL; the heating rate is 3℃ / min.

[0067] Step 2.2, the preparation method of modified carbon and nitrogen nanoparticles is as follows: First, prepare a sulfuric acid solution; add carbon and nitrogen nanocomposite particles to the sulfuric acid solution, disperse by ultrasonication to obtain a mixture; add the mixture dropwise to methanol while stirring, and continue stirring for 30 minutes after the addition is complete, then let it stand for 2 hours, filter it, wash it with water until neutral, and dry it under vacuum to obtain modified carbon and nitrogen nanoparticles.

[0068] The sulfuric acid solution has a mass fraction of 60%.

[0069] The mixing ratio of carbon-nitrogen nanocomposite particles and sulfuric acid solution is 19g:200mL; the volume ratio of the mixture to methanol is 1:2.

[0070] The vacuum drying temperature is 60℃ and the time is 10 hours.

[0071] In step 2, the mixing ratio of octadecyl dimethyl allyl ammonium chloride, modified carbon-nitrogen nanoparticles, and xylene is 25g:0.42g:150mL.

[0072] Step 3: Mix the first mixture and the dispersion together, and then shear for 1.3 hours to obtain the shearing liquid; the volume ratio of the first mixture and the dispersion is 1:1. Step 4: Add the obtained shearing liquid to the reactor, then introduce nitrogen into the reactor to purge the air inside, adjust the temperature to 70°C, keep it at this temperature and stir for 10 minutes, then add the initiator and continue stirring for 11 hours to obtain the reaction liquid; the initiator is azobisisobutyronitrile; the amount of azobisisobutyronitrile added is 2.8% of the mass of the shearing liquid.

[0073] Step 5: Add the reaction solution to isopropanol at a volume ratio of 1:1.5, stir for 40 minutes, let stand for 2 hours, filter, and obtain the reaction material; Step 6: Wash the reaction material with anhydrous ethanol and methanol for 10 minutes respectively, and then dry it to obtain an environmentally friendly salt-resistant and high-temperature filtration loss reducing agent for long naked eye segments.

[0074] Example 5: Preparation method of environmentally friendly salt-resistant and high-temperature resistant filtration loss reducing agent for long naked eye segment, including the following steps: Step 1, acrylamide and 2-acrylamide-2-methylpropanesulfonic acid are added to deionized water in sequence and stirred and mixed evenly to obtain a composite solution; the molar ratio of acrylamide to 2-acrylamide-2-methylpropanesulfonic acid is 3:1; the mass ratio of acrylamide to deionized water is 1.5:6.

[0075] Step 1.2: Adjust the pH of the composite solution to 8.3, then add Tween-80 and continue stirring to obtain the first mixture; adjust the pH of the composite solution using sodium hydroxide solution; wherein, the mass fraction of sodium hydroxide solution is 10%; the amount of Tween-80 added is 6% of the mass of the composite solution.

[0076] Step 2: Prepare carbon-nitrogen nanocomposite particles and modify them to obtain modified carbon-nitrogen nanoparticles. Octadecyldimethylallylammonium chloride and the modified carbon-nitrogen nanoparticles are sequentially added to xylene and dispersed by ultrasonication to obtain a dispersion. Specifically: Step 2.1, the preparation method of carbon-nitrogen nanocomposite particles is as follows: Melamine is added to methanol and dissolved by stirring to obtain a melamine-methanol solution; nano-silica is added to the melamine-methanol solution and dispersed by ultrasonication to obtain a composite dispersion; the composite dispersion is dried by rotary evaporation to obtain a composite material; the composite material is placed in a tube furnace and heated to 600℃ in an air atmosphere, held for 2 hours, and then cooled to room temperature to obtain carbon-nitrogen nanocomposite particles; the mixing ratio of melamine and methanol is 30g:130mL; the mixing ratio of nano-silica and melamine-methanol solution is 1.5g:130mL; the heating rate is 3℃ / min.

[0077] Step 2.2, the preparation method of modified carbon and nitrogen nanoparticles is as follows: First, prepare a sulfuric acid solution; add carbon and nitrogen nanocomposite particles to the sulfuric acid solution, disperse by ultrasonication to obtain a mixture; add the mixture dropwise to methanol while stirring, and continue stirring for 30 minutes after the addition is complete, then let it stand for 2 hours, filter it, wash it with water until neutral, and dry it under vacuum to obtain modified carbon and nitrogen nanoparticles.

[0078] The sulfuric acid solution has a mass fraction of 60%.

[0079] The mixing ratio of carbon-nitrogen nanocomposite particles and sulfuric acid solution is 20g:200mL; the volume ratio of the mixture to methanol is 1:2.

[0080] The vacuum drying temperature is 60℃ and the time is 10 hours.

[0081] In step 2, the mixing ratio of octadecyl dimethyl allyl ammonium chloride, modified carbon-nitrogen nanoparticles, and xylene is 30g:0.5g:150mL.

[0082] Step 3: Mix the first mixture and the dispersion together, and then shear for 2 hours to obtain a shearing liquid; the volume ratio of the first mixture and the dispersion is 1:1. Step 4: Add the obtained shearing liquid to the reactor, then introduce nitrogen gas into the reactor to purge the air inside the reactor, adjust the temperature to 70°C, keep it at this temperature and stir for 10 minutes, then add the initiator and continue stirring for 12 hours to obtain a reaction liquid; the initiator is azobisisobutyronitrile; the amount of azobisisobutyronitrile added is 3% of the mass of the shearing liquid.

[0083] Step 5: Add the reaction solution to isopropanol at a volume ratio of 1:1.5, stir for 40 minutes, let stand for 2 hours, filter, and obtain the reaction material; Step 6: Wash the reaction material with anhydrous ethanol and methanol for 10 minutes respectively, and then dry it to obtain an environmentally friendly salt-resistant and high-temperature filtration loss reducing agent for long naked eye segments.

[0084] Comparative Example 1: Based on the technical solution of Example 3, no carbon-nitrogen nanocomposite particles were added, and the rest of the technical solution remained unchanged.

[0085] Comparative Example 2: Based on the technical solution of Example 3, the carbon-nitrogen nanocomposite particles were replaced with nano-nitrogen carbonide particles, while the rest of the technical solution remained unchanged.

[0086] Experiment: 100 mg of each of the samples from Example 3 and Comparative Example 1 were subjected to thermogravimetric analysis (TG) in a nitrogen atmosphere. The initial temperature was 20 °C, the heating rate was 10 °C / min, and the final temperature was 820 °C. The three temperature ranges of the main weight loss of each group were compared: Table 1.

[0087]

[0088] As can be seen from Table 1, the filtration loss reducer prepared in this invention has excellent high-temperature stability.

[0089] Filtration loss reduction test: 15g of bentonite and 0.78g of anhydrous sodium carbonate were added to the mixture, and it was stirred at high speed at 8500r / min for 40min. After curing at room temperature in a sealed environment for 24h, a fresh water-based slurry was obtained.

[0090] Take 200g of freshwater-based slurry from each sample, and then add 0.85% by mass of the sample from Example 3 and the comparative sample to each sample. Stir at high speed for 2 hours.

[0091] According to the national standard GB / T16783.1—2014 "Field Testing of Drilling Fluids for Petroleum and Natural Gas Industry", the viscosity and filtration loss of the system after aging at 150℃ for 16 hours were measured using a six-speed rotational viscometer and a medium-pressure fluid loss meter. A set of fresh water-based slurry was set up as a blank control group. Table 2 shows the system before aging.

[0092] Table 3 and Table 2 after aging

[0093] As can be seen from Tables 2 and 3, in freshwater-based slurry, with the introduction of the sample from Example 3, the apparent viscosity and dynamic shear force of the test slurry increased significantly. After aging, the apparent viscosity was significantly improved, the dynamic shear force was also significantly improved, the overall rheological properties were greatly improved, the filtration loss was low, and the filtration performance was excellent.

[0094] Add 15g of bentonite and 0.78g of anhydrous sodium carbonate to the mixture, stir at high speed at 8500r / min for 40min, and cure at room temperature in a sealed environment for 24h to obtain a fresh water-based slurry.

[0095] Add 0.85% by mass of the sample from Example 3, stir at high speed for 2 hours, adjust the sodium chloride content of the slurry to different levels, and compare the effect of different sodium chloride contents on the filtration loss reduction performance of the slurry after aging at 150°C for 15 hours, as shown in Figure 1. As can be seen from Figure 1, after introducing the filtration loss reducer prepared in this invention, the effect on the filtration loss reduction performance of the slurry is small at different sodium chloride contents, indicating that the filtration loss reducer prepared in this invention has excellent salt resistance.

Claims

1. A method for preparing an environmentally friendly, salt-resistant, high-temperature-resistant filtration loss reducing agent for long naked-eye segments, characterized in that, The specific steps are as follows: Step 1, prepare the first mixture; Step 2, prepare carbon-nitrogen nanocomposite particles, modify them to obtain modified carbon-nitrogen nanoparticles, add octadecyl dimethyl allyl ammonium chloride and modified carbon-nitrogen nanoparticles to xylene in sequence, and disperse them by ultrasonication to obtain a dispersion; Step 3, mix the first mixture and the dispersion, and then shear them for 1-2 hours to obtain a shearing liquid; the volume ratio of the first mixture to the dispersion is 1:1; Step 4, add the shearing liquid to the reactor, introduce nitrogen into the reactor to purge the air inside, maintain the temperature at 70℃, stir for 10 minutes, then add the initiator and stir for 10-12 hours to obtain a reaction solution; Step 5, add the reaction solution to isopropanol at a volume ratio of 1:1.5, stir for 40 minutes, let stand for 2 hours, filter, and obtain the reaction material; Step 6, wash the reaction material with anhydrous ethanol and methanol for 10 minutes each, and then dry it to obtain an environmentally friendly salt-resistant and high-temperature filtration loss reducing agent for use in the long naked eye segment.

2. The preparation method of the environmentally friendly, salt-resistant, high-temperature resistant filtration loss reducing agent for long naked-eye segments according to claim 1, characterized in that, Step 1 specifically comprises: Step 1.1, adding acrylamide and 2-acrylamide-2-methylpropanesulfonic acid sequentially to deionized water, stirring and mixing evenly to obtain a composite solution; Step 1.2, adjusting the pH of the composite solution to 8.3, then adding Tween-80, and continuing to stir and mix to obtain the first mixture.

3. The preparation method of the environmentally friendly, salt-resistant, high-temperature resistant filtration loss reducing agent for long naked-eye segments according to claim 2, characterized in that, In step 1.1, the molar ratio of acrylamide to 2-acrylamide-2-methylpropanesulfonic acid is 3:1; the mass ratio of acrylamide to deionized water is 1-1.5:

6.

4. The preparation method of the environmentally friendly, salt-resistant, high-temperature resistant filtration loss reducing agent for long naked-eye segments according to claim 3, characterized in that, In step 1.2, the pH of the composite solution is adjusted using sodium hydroxide solution with a mass fraction of 10%, and the amount of Tween-80 added is 5-6% of the mass of the composite solution.

5. The preparation method of the environmentally friendly, salt-resistant, high-temperature resistant filtration loss reducing agent for long naked-eye segments according to claim 4, characterized in that, Step 2 specifically comprises: Step 2.1, the preparation method of carbon-nitrogen nanocomposite particles is as follows: melamine is added to methanol and dissolved by stirring to obtain a melamine-methanol solution; nano-silica is added to the melamine-methanol solution and dispersed by ultrasonication to obtain a composite dispersion; the composite dispersion is dried by rotary evaporation to obtain a composite material; the composite material is placed in a tube furnace and heated to 580-600℃ in an air atmosphere, held at that temperature for 2 hours, and then cooled to room temperature to obtain carbon-nitrogen nanocomposite particles; wherein, the mixing ratio of melamine to methanol is 2:

1. 5-30g:130mL; the mixing ratio of nano-silica to melamine methanol solution is 1-1.5g:130mL; the heating rate is 3℃ / min; step 2.2, the preparation method of modified carbon-nitrogen nanoparticles is as follows: prepare sulfuric acid solution; add carbon-nitrogen nanocomposite particles to sulfuric acid solution, disperse by ultrasonication to obtain a mixture; add the mixture dropwise to methanol while stirring, after the addition is complete, continue stirring for 30min, then let stand for 2 hours, then filter, wash with water until neutral, and vacuum dry to obtain modified carbon-nitrogen nanoparticles.

6. The preparation method of the environmentally friendly, salt-resistant, high-temperature resistant filtration loss reducing agent for long naked-eye segments according to claim 5, characterized in that, In step 2.2, the sulfuric acid solution has a mass fraction of 60%; the ratio of the carbon-nitrogen nanocomposite particles to the sulfuric acid solution is 18-20g:200mL; the volume ratio of the mixture to methanol is 1:2; and the vacuum drying temperature is 60℃ for 10 hours.

7. The preparation method of the environmentally friendly, salt-resistant, high-temperature resistant filtration loss reducing agent for long naked-eye segments according to claim 6, characterized in that, In step 2, the mixing ratio of octadecyl dimethyl allyl ammonium chloride, modified carbon-nitrogen nanoparticles, and xylene is 20-30g: 0.4-0.5g: 150mL.

8. The preparation method of the environmentally friendly, salt-resistant, high-temperature resistant filtration loss reducing agent for long naked-eye segments according to claim 7, characterized in that, In step 4, the initiator is azobisisobutyronitrile (AIBN), and the amount of AIBN added is 2-3% of the mass of the shear fluid.

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