Phosphonic acid-benzenesulfonic acid double modified carbon microspheres, and preparation method and application thereof

Abstract

The present application relates to a kind of phosphonic acid-benzenesulfonic acid double modified carbon microspheres and its preparation method and application, belong to oil field chemical field.The method includes: S1 with biomass as raw material preparation original carbon microspheres;S2 original carbon microspheres are pre-oxidized and activated, obtain activated carbon microspheres;S3 activated carbon microspheres are phosphonated grafting reaction;S4 last perform sulfonic group grafting reaction.The present application also provides the phosphonic acid-benzenesulfonic acid double modified carbon microspheres prepared by this method, and the application of the phosphonic acid-benzenesulfonic acid double modified carbon microspheres in the preparation of water-based drilling fluid.In this phosphonic acid-benzenesulfonic acid double modified carbon microspheres, phosphonic acid group and benzenesulfonic acid group are introduced into the surface of carbon microspheres by stable covalent interaction, not easy to fall off in high temperature and high salt environment, can improve the stability of material in high temperature condition, to ensure that modified carbon microspheres in downhole complex working condition Long-term effect, make drilling fluid system can simultaneously withstand high temperature and high calcium ion double test.

Description

Technical Field

[0001] This invention belongs to the field of oilfield chemistry and relates to a phosphonic acid-benzenesulfonic acid dual-modified carbon microsphere, its preparation method, and its application. More specifically, it relates to a phosphonic acid-benzenesulfonic acid dual-functionalized carbon microsphere, its preparation method, and the application of this carbon microsphere as a water-based drilling fluid additive in deep and ultra-deep wells in high-temperature, high-calcium salt formations. Background Technology

[0002] As oil and gas exploration and development extend into deeper and more complex formations, formation temperatures rise significantly during deep and ultra-deep well drilling. Furthermore, complex conditions such as high-calcium salt formations and highly saline formation water are frequently encountered, severely impacting drilling fluid performance and posing significant challenges to safe and efficient drilling.

[0003] High temperatures accelerate the thermal oxidative degradation, hydrolysis, and thermal decomposition of polymer treatment agents in drilling fluids, leading to their degradation and failure. This, in turn, causes a deterioration or even loss of drilling fluid properties such as rheology and filtration. Simultaneously, calcium ions in formation water can disrupt the diffused electric double layer on clay particle surfaces, causing damage to the drilling fluid's colloidal system and worsening its rheological and filtration properties. Furthermore, calcium ions readily cross-link and precipitate with anionic treatment agents, further impairing the drilling fluid's rheological properties and filtration wall-building characteristics. To address the problem of drilling fluid performance deterioration caused by high-temperature, high-mineralization formations, the stability of the treatment agent itself can be improved by developing temperature- and calcium-resistant treatment agents, or by adding temperature- and calcium-resistant stabilizers to protect the drilling fluid treatment agent, thereby enhancing the stability of the drilling fluid system.

[0004] Sun Jinsheng et al. selected a high-temperature protective agent (GBH) as an additive for water-based drilling fluids, which significantly improved the high-temperature resistance and filtration reduction properties of sulfonated polymers, as well as their high-temperature stability, effectively enhancing the overall temperature resistance of the drilling fluid. Wang Yu et al. developed a low-molecular-weight organic high-temperature protective agent (EGC-D). This agent effectively maintained the viscosity of the drilling fluid by promoting moderate high-temperature crosslinking between polymeric filtration reducers and sulfonated filtration reducers, while significantly improving the dynamic-plastic ratio of the system. This greatly enhanced the drilling fluid's ability to carry cuttings, providing a new technical path for safe and efficient drilling in high-temperature environments. Currently, drilling fluid stabilizers are mainly high-temperature stabilizers targeting high-temperature problems, but they have not effectively solved the problem of drilling fluid performance failure caused by the combined effects of "high temperature and high calcium" in deep wells and high-calcium salt formations.

[0005] Carbon microspheres have good thermal stability and their surface contains abundant oxygen-containing functional groups. They can remove free radicals and dissolved oxygen through surface hydroxyl groups and internal aromatic structures. As a high-temperature stabilizer for water-based drilling fluids, they can improve the temperature resistance of water-based drilling fluids. They can also improve the calcium resistance of water-based drilling fluids to some extent by chelating calcium ions through surface carboxyl groups. However, they still have certain limitations in dealing with the complex working conditions of "high temperature-high calcium".

[0006] Therefore, developing a water-based drilling fluid stabilizer that combines calcium and temperature resistance and is suitable for extreme "high temperature-high calcium" conditions is of great significance for ensuring safe and efficient drilling of deep oil and gas resources. Summary of the Invention

[0007] To overcome the shortcomings of existing technologies, this invention provides phosphonic acid-benzenesulfonic acid dual-modified carbon microspheres, their preparation method, and applications. These carbon microspheres are surface-modified using phosphonic acid-benzenesulfonic acid dual functional groups, successfully introducing functional groups or structures with high thermal stability and strong chelating ability. This enhances the temperature and calcium resistance of water-based drilling fluids, giving them both calcium and temperature resistance properties, effectively solving the performance failure problem of water-based drilling fluids under extreme "high temperature-high calcium" conditions.

[0008] The technical solution of the present invention is as follows:

[0009] A method for preparing phosphonic acid-benzenesulfonic acid dual-modified carbon microspheres includes the following steps:

[0010] S1: Preparation of original carbon microspheres

[0011] Biomass was dispersed in a solvent to form a uniform and stable solution, and then hydrothermally reacted at 180~240℃ for 6~24h. The product after hydrothermal reaction was centrifuged, washed and dried to obtain the original carbon microspheres.

[0012] S2: Pre-oxidation activation

[0013] Concentrated nitric acid was added to the original carbon microspheres obtained in S1, and the mixture was refluxed at 100~150℃ for 2~8h. After the reaction was completed, the mixture was cooled to room temperature, separated by suction filtration, washed and dried under vacuum to obtain activated carbon microspheres (CMS-OH).

[0014] S3: Phosphonic grafting reaction

[0015] The activated carbon microspheres obtained from S2 were added to an organic solvent and ultrasonically dispersed for 25-35 min. Then, an inert gas was introduced to remove oxygen, followed by the addition of phosphorous acid and formaldehyde. The mixture was reacted at 70-85℃ and 500-800 r / min for 4-6 h to obtain a phosphonate intermediate suspension.

[0016] S4: Sulfonic acid group grafting reaction

[0017] p-Aminobenzenesulfonic acid and formaldehyde were added to the phosphonate intermediate suspension obtained in S3, and the mixture was reacted at 70-85℃ and 500-800 r / min for 2-4 h. After the reaction was completed, the mixture was naturally cooled to room temperature, and after centrifugation, washing and vacuum drying, phosphonic acid-benzenesulfonic acid dual-modified carbon microspheres were obtained.

[0018] According to a preferred embodiment of the present invention, in step S1, the solvent is deionized water; the biomass is glucose, xylose, cyclodextrin or starch; and the mass ratio of the biomass to the solvent is (5~25):100.

[0019] According to a preferred embodiment of the present invention, the specific steps of centrifugation, washing, and drying in step S1 are as follows:

[0020] First, centrifuge at 10000 r / min for 20 min. The precipitate obtained by centrifugation is washed alternately with anhydrous ethanol and deionized water. Repeat the centrifugation-washing process 3 times. Finally, dry under vacuum at 60℃ for 12 h.

[0021] According to a preferred embodiment of the present invention, in step S2, the mass concentration of the concentrated nitric acid is 60-70%; the mass-to-volume ratio of the original carbon microspheres to the concentrated nitric acid is (5-15) g: (200-400) mL.

[0022] More preferably, the mass concentration of the concentrated nitric acid is 68%; the mass-to-volume ratio of the original carbon microspheres to the concentrated nitric acid is 10g:300mL.

[0023] According to a preferred embodiment of the present invention, the specific steps of filtration separation, washing, and vacuum drying in step S2 are as follows:

[0024] The solid product was first separated by vacuum filtration, then washed with deionized water until the pH of the filtrate was 6-7, and finally dried under vacuum at 70°C for 12 hours.

[0025] According to a preferred embodiment of the present invention, in step S3, the organic solvent is anhydrous ethanol or isopropanol; the ultrasonic dispersion power is 200~300W; and the inert atmosphere is nitrogen or argon, with an introduction time of 25~35min.

[0026] According to a preferred embodiment of the present invention, in step S3, the mass concentration of formaldehyde is 35-40%; the mass-volume ratio of the organic solvent, activated carbon microspheres, phosphorous acid, and formaldehyde is (150-250) mL: (5-15) g: (10-20) g: (8-15) mL.

[0027] More preferably, the formaldehyde has a mass concentration of 37%; and the mass-to-volume ratio of the organic solvent, activated carbon microspheres, phosphorous acid, and formaldehyde is 200 mL: 10 g: 15 g: 10 mL.

[0028] According to a preferred embodiment of the present invention, in step S4, the mass concentration of formaldehyde is 35-40%; the mass-volume ratio of p-aminobenzenesulfonic acid, formaldehyde and organic solvent in step S3 is (1-5) g: (1-5) mL: (150-250) mL.

[0029] More preferably, the formaldehyde has a mass concentration of 37%; and the mass-to-volume ratio of p-aminobenzenesulfonic acid, formaldehyde, and the organic solvent in step S3 is 2g:3mL:200mL.

[0030] According to a preferred embodiment of the present invention, the specific steps of centrifugation, washing, and vacuum drying in step S4 are as follows:

[0031] First, centrifuge at 10000 r / min for 15 min to collect the solid product; then wash it three times alternately with anhydrous ethanol and deionized water, and finally vacuum dry it at 70℃ for 12 h.

[0032] A phosphonic acid-benzenesulfonic acid dual-modified carbon microsphere was prepared according to the above method.

[0033] The application of the above-mentioned phosphonic acid-benzenesulfonic acid dual-modified carbon microspheres in the preparation of water-based drilling fluids.

[0034] According to a preferred embodiment of the present invention, the concentration of phosphonic acid-benzenesulfonic acid dual-modified carbon microspheres in the water-based drilling fluid is 1~20 g / L.

[0035] Technical features of the present invention:

[0036] This invention discloses a method for preparing phosphonic acid-benzenesulfonic acid dual-modified carbon microspheres, employing a "two-step covalent grafting in the same system" approach. Using pre-oxidized and activated carbon microspheres as the matrix, phosphonation and benzenesulfonation reactions are carried out continuously in a single reaction system without separating intermediate products, stably introducing phosphonic acid and benzenesulfonic acid groups onto the surface of the carbon microspheres. Specifically, phosphorous acid reacts with formaldehyde to form an active hydroxymethylphosphonic acid intermediate, which reacts with oxygen-containing functional groups such as hydroxyl and carboxyl groups on the surface of the carbon microspheres, achieving phosphonic acid grafting. Subsequently, p-aminobenzenesulfonic acid undergoes a condensation reaction with formaldehyde, further grafting benzenesulfonic acid groups through a methylene bridge structure. Utilizing the synergistic effect of the dual functional groups and the functional groups on the surface of the carbon microspheres, the calcium and temperature resistance of water-based drilling fluids is improved by scavenging dissolved oxygen, chelating calcium ions, and stabilizing the polymer.

[0037] Furthermore, in step S3, phosphorous acid and formaldehyde react under heating conditions to form an active hydroxymethylphosphonic acid intermediate. This intermediate further reacts with oxygen-containing functional groups such as hydroxyl and carboxyl groups on the surface of the carbon microspheres, thereby introducing phosphonic acid groups onto the surface of the carbon microspheres. The specific reaction process is as follows:

[0038] .

[0039] In step S4, the reaction system temperature, inert atmosphere, and stirring rate are kept constant. Solid-liquid separation of the phosphonate intermediate suspension obtained in step S3 is not required. Further addition of p-aminobenzenesulfonic acid and formaldehyde leads to a condensation reaction, forming methylene bridges with the remaining active sites on the carbon microspheres. This stably introduces benzenesulfonic acid groups onto the carbon microsphere surface. The specific reaction process is as follows:

[0040]

[0041] Note: -Ar-H represents the active sites on the surface of carbon microspheres.

[0042] The beneficial effects of this invention are:

[0043] 1. This invention modifies the surface of carbon microspheres using a phosphonic acid-benzenesulfonic acid bifunctional group, successfully introducing functional groups or structures with high thermal stability and strong chelating ability, thus preparing phosphonic acid-benzenesulfonic acid bifunctional carbon microspheres. The phosphonic acid group exhibits a strong chelating effect on calcium ions, stabilizing the complexation of calcium ions and preventing them from reacting with the treatment agent. The rigid aromatic ring structure of the benzenesulfonic acid group endows the product with excellent thermal stability, while the sulfonate group assists in calcium resistance through steric hindrance and charge repulsion. Simultaneously, the ungrafted oxygen-containing functional groups and aromatic structures on the surface of the carbon microspheres can adsorb oxidizing substances and inhibit the thermo-oxidative degradation of the polymer, improving temperature resistance. Therefore, the phosphonic acid group, benzenesulfonic acid group, and oxygen-containing functional group can produce a synergistic effect, enabling the drilling fluid system to withstand both high temperature and high calcium ion levels simultaneously.

[0044] 2. In the preparation method of phosphonic acid-benzenesulfonic acid dual-modified carbon microspheres provided by this invention, the phosphonation reaction and the benzenesulfonation reaction are carried out in the same system and within a similar temperature range, eliminating the need for intermediate product separation and purification, which greatly simplifies the production process and improves preparation efficiency. Simultaneously, this method avoids the loss of active sites in intermediate products, ensuring a high grafting rate of bifunctional groups. The principle is that after the first-stage phosphonation, the active sites retained on the surface of the carbon microspheres can further participate in the subsequent condensation grafting reaction of p-aminobenzenesulfonic acid and formaldehyde, thereby achieving continuous introduction of bifunctional groups. This avoids the potential deactivation or contamination of active sites that may result from intermediate separation steps, thus realizing the continuous introduction of phosphonic acid groups and benzenesulfonic acid groups onto the surface of the carbon microspheres.

[0045] 3. In the phosphonic acid-benzenesulfonic acid dual-modified carbon microspheres provided by this invention, phosphonic acid groups and benzenesulfonic acid groups are introduced into the surface of the carbon microspheres through stable covalent interactions, making them less prone to detachment under high temperature and high salt environments. The phosphonic acid groups can effectively complex calcium ions, reducing the adverse effects of calcium ions on the drilling fluid system; the benzenesulfonic acid groups and aromatic structures have high thermal stability, which can improve the stability of the material under high temperature conditions, thereby ensuring the long-term effectiveness of the modified carbon microspheres in complex downhole conditions.

[0046] 4. The phosphonic acid-benzenesulfonic acid dual-modified carbon microspheres provided by this invention use biomass as raw material, which is environmentally friendly, low-cost, and green, and has advantages in both economic and environmental aspects. Attached Figure Description

[0047] Figure 1 This is a scanning electron microscope image of the phosphonic acid-benzenesulfonic acid dual-modified carbon microspheres CMS-PS-1 prepared in Example 1.

[0048] Figure 2 This is a particle size distribution diagram of the phosphonic acid-benzenesulfonic acid dual-modified carbon microspheres CMS-PS-1 prepared in Example 1.

[0049] Figure 3 The image shows the infrared spectrum of the phosphonic acid-benzenesulfonic acid dual-modified carbon microspheres CMS-PS-1 prepared in Example 1. Detailed Implementation

[0050] The present invention will be described in detail below through preferred embodiments and experimental data, but the scope of protection of the present invention is not limited thereto.

[0051] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0052] The present invention will be described in detail below through examples. Unless otherwise specified, the methods used in the following examples are conventional; the reagents and materials mentioned are commercially available unless otherwise specified.

[0053] Example 1

[0054] A method for preparing phosphonic acid-benzenesulfonic acid dual-modified carbon microspheres includes the following steps:

[0055] S1: Preparation of original carbon microspheres

[0056] 40g of glucose was added to 400mL of deionized water and stirred until fully dissolved to obtain a glucose solution. The glucose solution was then transferred to a hydrothermal reactor lined with polytetrafluoroethylene and placed in a roller heating furnace. The reactor was subjected to a rolling aging reaction at 180℃ for 8 hours. After the reaction was completed, the mixture was cooled to room temperature. The resulting dark brown suspension was centrifuged at 10000r / min for 20min. The precipitate obtained by centrifugation was washed alternately with anhydrous ethanol and deionized water. The centrifugation-washing process was repeated 3 times. The resulting solid product was placed in an oven and dried at 60℃ for 12 hours to obtain the original carbon microspheres with glucose as the carbon source, denoted as CMS-1.

[0057] S2: Pre-oxidation activation

[0058] 10g of CMS-1 obtained from S1 and 300mL of 68wt% concentrated nitric acid were added sequentially to a 500mL three-necked flask and refluxed at 120℃ in an oil bath for 6h. After the reaction was completed, the mixture was cooled to room temperature. The solid product was first separated by vacuum filtration, then washed with deionized water until the pH of the filtrate was 6-7, and finally dried under vacuum at 70℃ for 12h to obtain activated carbon microspheres.

[0059] S3: Phosphonic grafting reaction

[0060] 10g of activated carbon microspheres obtained from S2 and 200mL of anhydrous ethanol were added sequentially to a 500mL beaker and ultrasonically dispersed at 250W for 30min. The mixture was then transferred to a 500mL three-necked flask, and an inert gas was introduced to remove oxygen for 30min. 15g of phosphorous acid and 10mL of 37wt% formaldehyde solution were then added sequentially. The mixture was reacted at 75℃ and 600r / min for 5h to complete the phosphonation grafting reaction and obtain a phosphonation intermediate suspension.

[0061] S4: Sulfonic acid group grafting reaction

[0062] While maintaining constant temperature, nitrogen atmosphere, and stirring rate, 2g of p-aminobenzenesulfonic acid and 3mL of 37wt% formaldehyde solution were added to the phosphonate intermediate suspension obtained in S3. The mixture was reacted at 75℃ for 3h to complete the covalent introduction reaction of benzenesulfonic acid groups. After natural cooling to room temperature, the reaction solution was transferred to a centrifuge tube and centrifuged at 10000r / min for 15min. The solid product was collected, washed three times alternately with anhydrous ethanol and deionized water, and then vacuum dried at 70℃ for 12h to obtain phosphonic acid-benzenesulfonic acid dual-modified carbon microspheres, denoted as CMS-PS-1.

[0063] Then the average particle size and zeta potential of the original carbon microspheres CMS-1 obtained in S1 and the phosphonic acid-benzenesulfonic acid dual-modified carbon microspheres CMS-PS-1 obtained in S4 were determined.

[0064] The results showed that the average particle size of the original carbon microspheres CMS-1 was 420 nm and the Zeta potential was -31 mV; the average particle size of the phosphonic acid-benzenesulfonic acid dual-modified carbon microspheres CMS-PS-1 was 680 nm and the Zeta potential was -40 mV.

[0065] Next, the phosphonic acid-benzenesulfonic acid dual-modified carbon microspheres CMS-PS-1 prepared in this embodiment were observed by scanning electron microscopy, their particle size distribution was statistically analyzed, and their infrared spectroscopic analysis was performed. The results are as follows: Figures 1-3 As shown.

[0066] Depend on Figures 1-3 It can be seen that the phosphonic acid-benzenesulfonic acid dual-modified carbon microspheres CMS-PS-1 prepared in this embodiment have a spherical structure, D10=0.398, D50=0.680, and D90=1.270. Figure 1 , 2 The CMS-PS-1 infrared spectrum at 3399 cm⁻¹ -1 A broad and strong OH / NH stretching vibration peak is observed at 3129 cm⁻¹. -1 With 3056 cm -1 Aromatic CH stretching vibration peak appears at 2931 cm⁻¹. -1 and 1389cm -1 A peak of methylene CH stretching and bending vibrations appears at 1709 cm⁻¹. -1 A C=O stretching vibration peak appears at 1604 cm⁻¹. -1 With 1502 cm -1 The peak at 1181 cm⁻¹ is the vibrational peak of the aromatic C=C skeleton. -1 and 1035 cm -1 The strong and broad absorption bands at 930 cm⁻¹ represent overlapping coupling peaks of the S=O asymmetric stretching and P=O stretching vibrations, and the S=O symmetric stretching and PO stretching vibrations, respectively, proving the presence of phosphonic acid and benzenesulfonic acid groups; -1 The P-OH bending vibration peak at 753 cm⁻¹ and 753 cm⁻¹ -1 The PC stretching vibration peak at 695 cm⁻¹ further confirms the successful grafting of phosphonic acid groups. -1 With 593 cm -1 The SO stretching vibration peak at the point indicates the presence of benzenesulfonic acid groups. Figure 3 These data fully demonstrate that the phosphonic acid-benzenesulfonic acid dual-modified carbon microspheres CMS-PS-1 were successfully prepared in this embodiment.

[0067] Example 2

[0068] A method for preparing phosphonic acid-benzenesulfonic acid dual-modified carbon microspheres includes the following steps:

[0069] S1: Preparation of original carbon microspheres

[0070] 40g of xylose was added to 400mL of deionized water and stirred until fully dissolved to obtain a xylose solution. The xylose solution was then transferred to a hydrothermal reactor lined with polytetrafluoroethylene and placed in a roller furnace. The reactor was subjected to a rolling aging reaction at 200℃ for 12h. After the reaction was completed, the reactor was cooled to room temperature. The resulting dark brown suspension was centrifuged at 10000r / min for 20min. The precipitate obtained by centrifugation was washed alternately with anhydrous ethanol and deionized water. The centrifugation-washing process was repeated 3 times. The resulting solid product was placed in an oven and dried at 60℃ for 12h to obtain the original carbon microspheres with xylose as the carbon source, denoted as CMS-2.

[0071] S2: Pre-oxidation activation

[0072] 10g of CMS-2 obtained from S1 and 300mL of 68wt% concentrated nitric acid were added sequentially to a 500mL three-necked flask and refluxed at 120℃ in an oil bath for 6h. After the reaction was completed, the mixture was cooled to room temperature. The solid product was first separated by vacuum filtration, then washed with deionized water until the pH of the filtrate was 6-7, and finally dried under vacuum at 70℃ for 12h to obtain activated carbon microspheres.

[0073] S3: Phosphonic grafting reaction

[0074] 10g of activated carbon microspheres obtained from S2 and 200mL of anhydrous ethanol were added sequentially to a 500mL beaker and ultrasonically dispersed at 250W for 30min. The mixture was then transferred to a 500mL three-necked flask, and an inert gas was introduced to remove oxygen for 30min. 15g of phosphorous acid and 10mL of 37wt% formaldehyde solution were then added sequentially. The mixture was reacted at 75℃ and 600r / min for 5h to complete the phosphonation grafting reaction and obtain a phosphonation intermediate suspension.

[0075] S4: Sulfonic acid group grafting reaction

[0076] While maintaining constant temperature, nitrogen atmosphere, and stirring rate, 2g of p-aminobenzenesulfonic acid and 3mL of 37wt% formaldehyde solution were added to the phosphonate intermediate suspension obtained in S3. The mixture was reacted at 75℃ for 3h to complete the covalent introduction reaction of benzenesulfonic acid groups. After natural cooling to room temperature, the reaction solution was transferred to a centrifuge tube and centrifuged at 10000r / min for 15min. The solid product was collected, washed three times alternately with anhydrous ethanol and deionized water, and then vacuum dried at 70℃ for 12h to obtain phosphonic acid-benzenesulfonic acid dual-modified carbon microspheres, denoted as CMS-PS-2.

[0077] The average particle size and zeta potential of the original carbon microspheres CMS-2 obtained in S1 and the phosphonic acid-benzenesulfonic acid dual-modified carbon microspheres CMS-PS-2 obtained in S4 were determined.

[0078] The results showed that the average particle size of the original carbon microspheres CMS-2 was 712 nm and the Zeta potential was -35 mV; the average particle size of the phosphonic acid-benzenesulfonic acid dual-modified carbon microspheres CMS-PS-2 was 752 nm and the Zeta potential was -47 mV.

[0079] Example 3

[0080] A method for preparing phosphonic acid-benzenesulfonic acid dual-modified carbon microspheres includes the following steps:

[0081] S1: Preparation of original carbon microspheres

[0082] 45g of starch was added to 400mL of deionized water and stirred until fully dissolved to obtain a starch solution. The starch solution was then transferred to a hydrothermal reactor lined with polytetrafluoroethylene and placed in a roller heating furnace. The reactor was subjected to a rolling aging reaction at 200℃ for 8 hours. After the reaction was completed, the mixture was cooled to room temperature. The resulting dark brown suspension was centrifuged at 10000r / min for 20min. The precipitate obtained by centrifugation was washed alternately with anhydrous ethanol and deionized water. The centrifugation-washing process was repeated 3 times. The resulting solid product was placed in an oven and dried at 60℃ for 12 hours to obtain the original carbon microspheres with starch as the carbon source, denoted as CMS-3.

[0083] S2: Pre-oxidation activation

[0084] 10g of CMS-3 obtained from S1 and 300mL of 68wt% concentrated nitric acid were added sequentially to a 500mL three-necked flask and refluxed at 120℃ in an oil bath for 6h. After the reaction was completed, the mixture was cooled to room temperature. The solid product was first separated by vacuum filtration, then washed with deionized water until the pH of the filtrate was 6-7, and finally dried under vacuum at 70℃ for 12h to obtain activated carbon microspheres.

[0085] S3: Phosphonic grafting reaction

[0086] 10g of activated carbon microspheres obtained from S2 and 200mL of isopropanol were added sequentially to a 500mL beaker and ultrasonically dispersed at 250W for 30min. The mixture was then transferred to a 500mL three-necked flask, and inert gas was introduced to remove oxygen for 30min. 15g of phosphorous acid and 10mL of 37wt% formaldehyde solution were then added sequentially. The mixture was reacted at 80℃ and 700r / min for 4.5h to complete the phosphonation grafting reaction and obtain a phosphonation intermediate suspension.

[0087] S4: Sulfonic acid group grafting reaction

[0088] While maintaining constant temperature, nitrogen atmosphere, and stirring rate, 2g of p-aminobenzenesulfonic acid and 3mL of 37wt% formaldehyde solution were added to the phosphonate intermediate suspension obtained from S3. The mixture was reacted at 80℃ for 2.5h to complete the covalent introduction reaction of benzenesulfonic acid groups. After natural cooling to room temperature, the reaction solution was transferred to a centrifuge tube and centrifuged at 10000r / min for 15min. The solid product was collected, washed three times alternately with anhydrous ethanol and deionized water, and dried under vacuum at 70℃ for 12h to obtain phosphonic acid-benzenesulfonic acid dual-modified carbon microspheres, denoted as CMS-PS-3.

[0089] The average particle size and zeta potential of the original carbon microspheres CMS-3 obtained in S1 and the phosphonic acid-benzenesulfonic acid dual-modified carbon microspheres CMS-PS-3 obtained in S4 were determined.

[0090] The results showed that the average particle size of the original carbon microspheres CMS-3 was 2000 nm and the Zeta potential was -33 mV; the average particle size of the phosphonic acid-benzenesulfonic acid dual-modified carbon microspheres CMS-PS-3 was 2220 nm and the Zeta potential was -45 mV.

[0091] Comparative Example 1

[0092] Following step S1 in Example 1, original carbon microspheres CMS-1 with glucose as the carbon source were prepared.

[0093] Comparative Example 2

[0094] A method for preparing phosphonate-modified carbon microspheres includes the following steps:

[0095] S1: Preparation of original carbon microspheres

[0096] 40g of glucose was added to 400mL of deionized water and stirred until fully dissolved to obtain a glucose solution. The glucose solution was then transferred to a hydrothermal reactor lined with polytetrafluoroethylene and placed in a roller heating furnace. The reactor was subjected to a rolling aging reaction at 180℃ for 8 hours. After the reaction was completed, the reactor was cooled to room temperature. The resulting dark brown suspension was centrifuged at 10000r / min for 20min. The precipitate obtained by centrifugation was washed alternately with anhydrous ethanol and deionized water. The centrifugation-washing process was repeated 3 times. The resulting solid product was placed in an oven and dried at 60℃ for 12 hours to obtain the original carbon microspheres with glucose as the carbon source.

[0097] S2: Pre-oxidation activation

[0098] 10g of the original carbon microspheres obtained from S1 and 300mL of 68wt% concentrated nitric acid were added sequentially to a 500mL three-necked flask and refluxed at 120℃ in an oil bath for 6h. After the reaction was completed, the mixture was cooled to room temperature. The solid product was first separated by vacuum filtration, then washed with deionized water until the pH of the filtrate was 6-7, and finally dried under vacuum at 70℃ for 12h to obtain activated carbon microspheres.

[0099] S3: Phosphonic grafting reaction

[0100] 10g of activated carbon microspheres obtained from S2 and 200mL of anhydrous ethanol were added sequentially to a 500mL beaker and ultrasonically dispersed at 250W for 30min. The mixture was then transferred to a 500mL three-necked flask, and oxygen was purged by purging with inert gas for 30min. 15g of phosphorous acid and 10mL of 37wt% formaldehyde solution were then added sequentially. The mixture was reacted at 75℃ and 600r / min for 5h to complete the phosphonation grafting reaction. After natural cooling to room temperature, the reaction solution was transferred to a centrifuge tube and centrifuged at 10000r / min for 15min. The solid product was collected and washed three times alternately with anhydrous ethanol and deionized water. The product was then vacuum dried at 70℃ for 12h to obtain phosphonated carbon microspheres, denoted as CMS-P-1.

[0101] Comparative Example 3

[0102] A method for preparing sulfonated carbon microspheres includes the following steps:

[0103] S1: Preparation of original carbon microspheres

[0104] 40g of glucose was added to 400mL of deionized water and stirred until fully dissolved to obtain a glucose solution. The glucose solution was then transferred to a hydrothermal reactor lined with polytetrafluoroethylene and placed in a roller heating furnace. The reactor was subjected to a rolling aging reaction at 180℃ for 8 hours. After the reaction was completed, the reactor was cooled to room temperature. The resulting dark brown suspension was centrifuged at 10000r / min for 20min. The precipitate obtained by centrifugation was washed alternately with anhydrous ethanol and deionized water. The centrifugation-washing process was repeated 3 times. The resulting solid product was placed in an oven and dried at 60℃ for 12 hours to obtain the original carbon microspheres with glucose as the carbon source.

[0105] S2: Pre-oxidation activation

[0106] 10g of the original carbon microspheres obtained from S1 and 300mL of 68wt% concentrated nitric acid were added sequentially to a 500mL three-necked flask and refluxed at 120℃ in an oil bath for 6h. After the reaction was completed, the mixture was cooled to room temperature. The solid product was first separated by vacuum filtration, then washed with deionized water until the pH of the filtrate was 6-7, and finally dried under vacuum at 70℃ for 12h to obtain activated carbon microspheres.

[0107] S3: Sulfonic acid grafting reaction

[0108] 10g of activated carbon microspheres obtained from S2 were added to a 500mL three-necked flask, and then 200mL of 98wt% concentrated sulfuric acid was slowly added. The mixture was stirred with a glass rod for 5 minutes and reacted at 40℃ and 600r / min for 4 hours. After the sulfonation reaction was completed, the mixture was naturally cooled to room temperature. The reaction solution was transferred to a centrifuge tube and centrifuged at 10000r / min for 15 minutes. The solid product was collected and washed three times alternately with anhydrous ethanol and deionized water. The product was then dried under vacuum at 70℃ for 12 hours to obtain carbon microspheres that were only sulfonated, which were designated as CMS-S-1.

[0109] Comparative Example 4

[0110] Following step S1 in Example 2, the original carbon microspheres CMS-2 with xylose as the carbon source were prepared.

[0111] Comparative Example 5

[0112] A method for preparing phosphonated carbon microspheres, the specific steps are the same as those in Comparative Example 2, the only difference being that carbon microspheres CMS-2 prepared with xylose as the carbon source are activated and modified to finally obtain phosphonated carbon microspheres CMS-P-2.

[0113] Comparative Example 6

[0114] A method for preparing sulfonated carbon microspheres, the specific steps are the same as those in Comparative Example 3, the only difference being that carbon microspheres CMS-2 prepared with xylose as the carbon source are activated and modified to finally obtain carbon microspheres CMS-S-2 that are only sulfonated.

[0115] Comparative Example 7

[0116] Following step S1 in Example 3, original carbon microspheres CMS-3 with starch as the carbon source were prepared.

[0117] Comparative Example 8

[0118] A method for preparing phosphonated carbon microspheres, the specific steps are the same as those in Comparative Example 2, the only difference being that carbon microspheres CMS-3 prepared with starch as the carbon source are activated and modified to finally obtain phosphonated carbon microspheres CMS-P-3.

[0119] Comparative Example 9

[0120] A method for preparing sulfonated carbon microspheres, the specific steps are the same as those in Comparative Example 3, the only difference being that carbon microspheres CMS-3 prepared with starch as the carbon source are activated and modified to finally obtain carbon microspheres CMS-S-3 with only sulfonation.

[0121] Test Example 1

[0122] Add 16g of sodium-based bentonite for drilling fluid (Huawei Bentonite Co., Ltd.) to 400mL of tap water, stir at 10000r / min for 30min, and then seal and let stand for 24h to obtain a pre-hydrated 4% bentonite-based slurry.

[0123] 0.3g NaOH and 2.4g xanthan gum (Ordos Zhongxuan Biochemical Co., Ltd.) were added sequentially to 400mL of bentonite-based slurry, and stirred at 10000r / min for 20min to obtain the basic experimental slurry.

[0124] Then, 4g of the phosphonic acid-benzenesulfonic acid dual-modified carbon microspheres CMS-PS-1, CMS-PS-2, and CMS-PS-3 prepared in Examples 1-3, and the CMS-1, CMS-P-1, CMS-S-1, CMS-2, CMS-P-2, CMS-S-2, CMS-S-2, CMS-3, CMS-P-3, and CMS-S-3 prepared in Comparative Examples 1-9 were added to 400mL of basic experimental slurry, resulting in a total of 12 test samples. Next, 5.5g of CaCl2 was added to each test sample to adjust the Ca... 2+ The concentration was adjusted to 5000 mg / L. After stirring at 10000 rpm for 20 min, the slurry was placed in an aging tank. The aging tank was then sealed and placed in a high-temperature roller furnace for hot rolling at 150°C for 16 h. After hot rolling, the slurry was allowed to cool to room temperature and stirred at 10000 rpm for 10 min before testing its properties. Simultaneously, a basic experimental slurry without carbon microspheres was prepared according to this procedure as a blank control group.

[0125] According to the test method of GB / T16783.2-2012, the readings of different experimental slurries at 600 rpm, 300 rpm, 200 rpm, 100 rpm, 6 rpm and 3 rpm were measured using a ZNN-D6 six-speed rotational viscometer. Then, the apparent viscosity (AV), plastic viscosity (PV), dynamic shear force (YP) and API filtration loss (FL) were calculated. API The test results are shown in Table 1 below.

[0126] Table 1

[0127]

[0128] Note: AV retention rate = (AV after hot rolling / AV before hot rolling) × 100%

[0129] Table 1 shows that at 150℃ and 5000 mg / L Ca 2+Under the given conditions, the viscosity retention and filtration loss control of the phosphonic acid-benzenesulfonic acid dual-modified carbon microspheres CMS-PS-1, CMS-PS-2, and CMS-PS-3 prepared in Examples 1-3 were significantly better than those of the unmodified carbon microspheres, the phosphonic acid-modified carbon microspheres, and the sulfonated carbon microspheres prepared in Comparative Examples 1-9.

[0130] Test Example 2

[0131] Six test samples were obtained by adding 0.4 g, 1.2 g, 2 g, 4 g, 6 g, and 8 g of the phosphonic acid-benzenesulfonic acid dual-modified carbon microspheres CMS-PS-2 prepared in Example 2 to 400 mL of the basic experimental slurry obtained in Test Example 1, respectively. Then, 5.5 g of CaCl2 was added to each sample to adjust the Ca2+ content. 2+ The concentration was adjusted to 5000 mg / L. After stirring at 10000 r / min for 20 min, the slurry was placed in an aging tank. The aging tank was then sealed and placed in a high-temperature roller furnace for hot rolling at 150℃ for 16 h. After hot rolling, the slurry was allowed to cool to room temperature and stirred at 10000 r / min for 10 min before testing its properties. The test method was the same as in Test Example 1, and the test results are shown in Table 2 below.

[0132] Table 2

[0133]

[0134] As shown in Table 2, when the dosage of the phosphonic acid-benzenesulfonic acid dual-modified carbon microspheres CMS-PS-2 prepared in Example 2 is 0.3-2%, it can provide certain rheological properties and filtration loss control under high temperature and high calcium conditions. When the dosage is 0.3-1.5%, the rheological adjustment and filtration loss reduction effects increase with increasing dosage. When the dosage reaches 1%, the system performance tends to stabilize, and further increasing the dosage has limited improvement. Therefore, when using CMS-PS-2 to prepare water-based drilling fluid, a dosage of 1% is preferred.

[0135] Test Example 3

[0136] 0.3 g NaOH and 2 g AM-AMPS-AA copolymer were added sequentially to 400 mL of the bentonite-based slurry obtained in Test Example 1, and the mixture was stirred at 10000 r / min for 20 min to obtain the basic experimental slurry.

[0137] Then, 0g, 2g, and 4g of the phosphonic acid-benzenesulfonic acid dual-modified carbon microspheres CMS-PS-2 prepared in Example 2 were added to 400mL of basic experimental slurry, respectively, to obtain a total of 3 test samples. Next, 6.6g of CaCl2 was added to each test sample to adjust the Ca... 2+The concentration was adjusted to 6000 mg / L. After stirring at 10000 r / min for 20 min, the slurry was placed in an aging tank. The aging tank was then sealed and placed in a high-temperature roller furnace for hot rolling at 220℃ for 16 h. After hot rolling, the slurry was allowed to cool to room temperature and stirred at 10000 r / min for 10 min before testing its properties. The test method was the same as in Test Example 1, and the test results are shown in Table 3 below.

[0138] Table 3

[0139]

[0140] As shown in Table 3, the phosphonic acid-benzenesulfonic acid dual-modified carbon microspheres CMS-PS-2 prepared in Example 2 can effectively chelate calcium ions and remove dissolved oxygen, so that the bentonite slurry containing polymers can still maintain high viscosity and low filtration loss after high temperature and high calcium aging.

[0141] Test Example 4

[0142] Take Ca from a certain oil field 2+ Concentration 6200 mg / L, density 1.25 g / cm³ 3 400 mL of on-site water-based drilling fluid (clean water + KCl + polyamine inhibitor + PAC-LV + SMP-2 + XC + FT-150 + high acid soluble sulfonated asphalt + liquid lubricant + plugging agent + coating agent + NaOH + ultrafine calcium carbonate + weighting agent) was prepared. 1% by mass of the phosphonic acid-benzenesulfonic acid dual-modified carbon microspheres CMS-PS-2 prepared in Example 2 and the foreign salt- and temperature-resistant treatment agent Driscal-D were added to each. After stirring at 10000 r / min for 20 min, the slurry was placed in an aging tank. The aging tank was sealed and placed in a high-temperature roller heating furnace at 220℃ for 16 h before testing the drilling fluid performance. The test method was the same as in Test Example 1, and the test results are shown in Table 4.

[0143] Table 4

[0144]

[0145] As shown in Table 4, after aging at 220℃, the surface viscosity retention rate of the drilling fluid with 1% of the phosphonic acid-benzenesulfonic acid dual-modified carbon microspheres CMS-PS-2 prepared in Example 2 was 88.89%, while the surface viscosity retention rate of the drilling fluid with 1% of the foreign salt and temperature resistant treatment agent Driscal-D was 74.73%. This indicates that under high temperature and high calcium conditions, the phosphonic acid-benzenesulfonic acid dual-modified carbon microspheres CMS-PS-2 prepared in Example 2 of this invention has a better effect on maintaining the apparent viscosity of the drilling fluid than the commercially available control product.

[0146] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, and these simple modifications all fall within the protection scope of the present invention. Furthermore, it should be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately. In addition, various different embodiments of the present invention can also be arbitrarily combined, as long as they do not violate the spirit of the present invention, they should also be considered as the content disclosed by the present invention.

Claims

1. A method for preparing phosphonic acid-benzenesulfonic acid dual-modified carbon microspheres, characterized in that, The steps include the following: S1: Preparation of original carbon microspheres Biomass was dispersed in a solvent to form a uniform and stable solution, and then hydrothermally reacted at 180~240℃ for 6~24h. The product after hydrothermal reaction was centrifuged, washed and dried to obtain the original carbon microspheres. S2: Pre-oxidation activation Concentrated nitric acid was added to the original carbon microspheres obtained in S1, and the mixture was refluxed at 100~150℃ for 2~8h. After the reaction was completed, the mixture was cooled to room temperature, separated by suction filtration, washed and dried under vacuum to obtain activated carbon microspheres (CMS-OH). S3: Phosphonic grafting reaction The activated carbon microspheres obtained from S2 were added to an organic solvent and ultrasonically dispersed for 25-35 min. Then, an inert gas was introduced to remove oxygen, followed by the addition of phosphorous acid and formaldehyde. The mixture was reacted at 70-85℃ and 500-800 r / min for 4-6 h to obtain a phosphonate intermediate suspension. S4: Sulfonic acid group grafting reaction p-Aminobenzenesulfonic acid and formaldehyde were added to the phosphonate intermediate suspension obtained in S3, and the mixture was reacted at 70-85℃ and 500-800 r / min for 2-4 h. After the reaction was completed, the mixture was naturally cooled to room temperature, and after centrifugation, washing and vacuum drying, phosphonic acid-benzenesulfonic acid dual-modified carbon microspheres were obtained.

2. The preparation method according to claim 1, characterized in that, In step S1, the solvent is deionized water; the biomass is glucose, xylose, cyclodextrin, or starch; and the mass ratio of biomass to solvent is (5~25):

100. The specific steps of centrifugation, washing, and drying are as follows: First, centrifuge at 10000 r / min for 20 min. The precipitate obtained by centrifugation is washed alternately with anhydrous ethanol and deionized water. The centrifugation-washing process is repeated 3 times. Finally, the precipitate is dried under vacuum at 60℃ for 12 h.

3. The preparation method according to claim 1, characterized in that, In step S2, the mass concentration of the concentrated nitric acid is 60-70%; the mass-volume ratio of the original carbon microspheres to the concentrated nitric acid is (5-15) g: (200-400) mL; the specific steps of the filtration separation, washing and vacuum drying are as follows: first, the solid product is separated by filtration, then washed with deionized water until the pH of the filtrate is 6-7, and finally vacuum dried at 70°C for 12 h. More preferably, the mass concentration of the concentrated nitric acid is 68%; the mass-to-volume ratio of the original carbon microspheres to the concentrated nitric acid is 10g:300mL.

4. The preparation method according to claim 1, characterized in that, In step S3, the organic solvent is anhydrous ethanol or isopropanol; the ultrasonic dispersion power is 200~300W; the inert atmosphere is nitrogen or argon, and the introduction time is 25~35min.

5. The preparation method according to claim 1, characterized in that, In step S3, the mass concentration of formaldehyde is 35-40%; the mass-volume ratio of organic solvent, activated carbon microspheres, phosphorous acid, and formaldehyde is (150-250) mL: (5-15) g: (10-20) g: (8-15) mL; More preferably, the formaldehyde has a mass concentration of 37%; and the mass-to-volume ratio of the organic solvent, activated carbon microspheres, phosphorous acid, and formaldehyde is 200 mL: 10 g: 15 g: 10 mL.

6. The preparation method according to claim 1, characterized in that, In step S4, the mass concentration of formaldehyde is 35-40%; the mass-volume ratio of p-aminobenzenesulfonic acid, formaldehyde, and organic solvent in step S3 is (1-5) g: (1-5) mL: (150-250) mL; the specific steps of centrifugation, washing, and vacuum drying are as follows: first, centrifuge at 10000 r / min for 15 min and collect the solid product; then wash with anhydrous ethanol and deionized water alternately 3 times, and finally vacuum dry at 70℃ for 12 h; More preferably, the formaldehyde has a mass concentration of 37%; and the mass-to-volume ratio of p-aminobenzenesulfonic acid, formaldehyde, and the organic solvent in step S3 is 2g:3mL:200mL.

7. A phosphonic acid-benzenesulfonic acid dual-modified carbon microsphere, characterized in that, It is prepared according to the method described in any one of claims 1 to 6.

8. The application of the phosphonic acid-benzenesulfonic acid dual-modified carbon microspheres according to claim 7 in the preparation of water-based drilling fluids.

9. The application as described in claim 8, characterized in that, The concentration of phosphonic acid-benzenesulfonic acid dual-modified carbon microspheres in the water-based drilling fluid is 1~20 g / L.

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