High-salt-resistant corrosion inhibition type nano imbibition agent as well as preparation method and application thereof

Abstract

The invention provides a high-salt-resistant corrosion inhibition type nano imbibition agent as well as a preparation method and application thereof, and the high-salt-resistant corrosion inhibition type nano imbibition agent comprises the following components in percentage by weight: 8-12% of polyethylene glycol-b-polycaprolactone, 5-10% of sodium gluconate, 5-10% of cellulose derivatives, 0.3% of oilfield-grade benzotriazole, 0.6% of industrial-grade sodium pyrophosphate and the balance of a dispersion medium. The cellulose derivative is a cellulose derivative activated by a silane coupling agent with a mass fraction of 0.5%. Therefore, a three-dimensional porous network constructed by the sodium carboxymethyl cellulose is activated, and the dispersion stability and the water retention imbibition capacity of the system are improved; the polyethylene glycol-b-polycaprolactone reduces the oil-water interfacial tension by virtue of an amphiphilic structure and accelerates imbibition and permeation; the sodium gluconate and the sodium pyrophosphate synergistically chelate high-salt ions, so that the salt resistance is enhanced. In addition, benzotriazole forms a compact protective film on the metal surface, and efficient corrosion inhibition is achieved in combination with the anti-scaling and corrosion inhibition effects of sodium pyrophosphate.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of oil exploitation, in particular to a high-salt-resistant corrosion-inhibiting nano-imbibition agent, a preparation method and application thereof. BACKGROUND

[0002] In the field of oil and gas exploitation, the development of high-salt reservoirs (usually referring to the total salinity of formation water exceeding 100,000 mg / L) has become an important direction for efficient utilization of global oil and gas resources. According to statistics of the oil industry, such reservoirs account for more than 30% of proven oil and gas reserves in China, and a higher proportion in the Middle East and Central Asia, etc. However, due to the special environment of high salinity and high content of corrosive ions in the formation water of such reservoirs, the exploitation process faces the problems of low imbibition efficiency and easy corrosion of metal equipment, which restricts the development efficiency and production safety.

[0003] From the perspective of imbibition efficiency, conventional imbibition agents mostly use ordinary nanoparticles or linear polymers as core components, which are prone to agglomeration due to the electrostatic shielding effect of salt ions in a high-salt environment. For example, imbibition agents using unmodified nanosilica as a carrier have a significantly decreased dispersion stability in formation water with a salinity exceeding 150,000 mg / L, and cannot effectively penetrate into the small pores of the reservoir (the pore diameter of conventional sandstone reservoirs is mostly 50-100 nm), resulting in limited imbibition to the near-wellbore zone of the reservoir and a greatly reduced effect of oil stripping and displacement. At the same time, the high-salt environment can disrupt the interfacial interaction balance of the imbibition agent with crude oil and rock, making it impossible to stably maintain the oil-water interfacial tension at a low value range required for efficient imbibition, further reducing the oil recovery rate.

[0004] In addition, the formation water of high-salt reservoirs is rich in corrosive ions such as Cl - , Ca 2+ , Mg 2+ , etc., among which the Cl - concentration can reach more than 100,000 mg / L, which can accelerate the electrochemical corrosion of oil pipes, casings and oil production equipment, forming defects such as pitting and stress corrosion cracking, increasing maintenance costs and downtime losses.

[0005] Therefore, there is an urgent need for a nano-imbibition agent to solve the problems in the prior art. SUMMARY

[0006] The main purpose of the present application is to provide a high-salt-resistant corrosion-inhibiting nano-imbibition agent, a preparation method and application thereof, to at least solve the problems of easy agglomeration, low imbibition efficiency and lack of effective corrosion inhibition of conventional imbibition agents in high-salt reservoirs in the prior art.

[0007] In order to achieve the above object, the application provides a high-salt-resistant corrosion-inhibiting nano-imbibition agent, which comprises, in percentage by weight, 8-12% polyethylene glycol-b-poly caprolactone, 5-10% sodium gluconate, 5-10% nanoscale cellulose derivative, 0.3% oilfield-grade benzotriazole, 0.6% industrial-grade sodium pyrophosphate, and the balance is a dispersion medium, the sum of the percentage by weight of the components being 100%; the cellulose derivative is a cellulose derivative activated by 0.5% silane coupling agent.

[0008] Optionally, the silane coupling agent is an amino-based silane coupling agent.

[0009] Optionally, the cellulose derivative is sodium carboxymethyl cellulose.

[0010] Optionally, the dispersion medium is deionized water or simulated reservoir brine with a total salinity of ≤200,000 mg / L.

[0011] The application also provides a preparation method of the high-salt-resistant corrosion-inhibiting nano-imbibition agent, which is applied to the high-salt-resistant corrosion-inhibiting nano-imbibition agent and comprises the following steps: Step 1, raw material pretreatment: benzotriazole ethanol solution and sodium pyrophosphate aqueous solution are respectively prepared, the cellulose derivative is activated by a silane coupling agent, and the sodium pyrophosphate aqueous solution is mixed with sodium gluconate to obtain a mixed solution; Step 2, construction of porous suspension: the activated cellulose derivative is added to the dispersion medium, and after ultrasonic dispersion, a trace amount of nitrogen is bubbled to form a cellulose derivative suspension with uniform porous structure; Step 3, component mixing: under stirring, the benzotriazole ethanol solution, the sodium pyrophosphate-sodium gluconate mixed solution and the polyethylene glycol-b-poly caprolactone are sequentially added to the suspension obtained in Step 2, and stirring is performed until the mixture is uniform; Step 4, standing and detection: the mixture system obtained in Step 3 is allowed to stand for 10 min, and the sample is detected; the pH value is 6.0-8.0, and the nanoparticle dispersion particle size is ≤30 nm, so that a qualified high-salt-resistant corrosion-inhibiting nano-imbibition agent is obtained.

[0012] Optionally, in Step 1, the preparation process of the benzotriazole ethanol solution is as follows: the formula amount of oilfield-grade benzotriazole is taken, 3-5 times the mass of industrial ethanol is added, and stirring is performed at 25-30°C for 10-15 min until complete dissolution. The preparation process of the sodium pyrophosphate aqueous solution is as follows: the formula amount of industrial-grade sodium pyrophosphate is taken, 8-10 times the mass of 30°C warm water is added, and stirring is performed for 5-8 min until complete dissolution.

[0013] Optionally, in the step 1, the cellulose derivative is sodium carboxymethyl cellulose, the silane coupling agent is amino silane coupling agent, and the process of activating the cellulose derivative by the silane coupling agent is as follows: Take a formula amount of sodium carboxymethyl cellulose, add 5-8 times of deionized water in mass, and perform ultrasonic pore forming under the condition of power 180-220 W and frequency 25 kHz for 15-20 min; then add 0.5% amino silane coupling agent solution in mass fraction, and stir at 35-40 DEG C for 20-30 min to complete the activation process; wherein the amount of amino silane coupling agent is 10-15 times of the mass of sodium carboxymethyl cellulose. After activation, filter and wash with deionized water for 2-3 times to remove excess amino silane coupling agent; and detect the specific surface area of sodium carboxymethyl cellulose after activation to ensure that the specific surface area of the cellulose derivative is greater than or equal to 150 m² / g.

[0014] Optionally, in the step 2, the ultrasonic dispersion parameters are power 200-300 W, frequency 20-25 kHz, and dispersion time 20-30 min; and the nitrogen bubbling flow is 5-10 mL / min and the bubbling time is 15-20 min.

[0015] Optionally, in the step 3, the stirring speed after adding the benzotriazole ethanol solution is 300-500 r / min, and the stirring time is 15-20 min; after adding the mixed solution, continue to stir for 10-15 min; after adding the polyethylene glycol-b-poly caprolactone, the stirring speed is increased to 600-800 r / min, and the stirring time is 25-30 min.

[0016] The application also provides a high-salt-resistant corrosion-inhibiting nano-imbibition agent as described in the application for use in oil and gas exploitation.

[0017] The application provides a high-salt-resistant corrosion-inhibiting nano-imbibition agent, a preparation method and application thereof, and the high-salt-resistant corrosion-inhibiting nano-imbibition agent comprises, in percentage by weight, 8-12% polyethylene glycol-b-poly caprolactone, 5-10% sodium gluconate, 5-10% nanoscale cellulose derivative, 0.3% oil field grade benzotriazole, 0.6% industrial grade sodium pyrophosphate, and the balance is a dispersion medium, and the sum of the percentage by weight of the components is 100%; the cellulose derivative is a cellulose derivative activated by 0.5% silane coupling agent in mass fraction. BRIEF DESCRIPTION OF DRAWINGS

[0018] The accompanying drawings, which form a part of this specification, are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the application and, together with the description, serve to explain the application without imposing undue limitation thereof. In the drawings: Figure 1 is an optional high-salt-resistant corrosion-inhibiting type nano-impregnating agent preparation method flow chart according to an embodiment of the application. DETAILED DESCRIPTION

[0019] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0020] The present application provides a high-salt-resistant corrosion-inhibiting type nano-impregnating agent, which comprises, by weight percentage: 8-12% polyethylene glycol-b-poly caprolactone, 5-10% sodium gluconate, 5-10% nanoscale cellulose derivative, 0.3% oil field grade benzotriazole, 0.6% industrial grade sodium pyrophosphate, and the balance is a dispersion medium, the sum of the weight percentages of the components is 100%; and the cellulose derivative is a cellulose derivative activated by 0.5% silane coupling agent.

[0021] Specifically, the polyethylene glycol-b-poly caprolactone serves as an amphiphilic block copolymer, and has both hydrophilic polyethylene glycol segments and hydrophobic poly caprolactone segments; the sodium gluconate is a water-soluble chelating agent with strong metal ion complexing ability; the cellulose derivative is activated by 0.5% silane coupling agent, and active functional groups are introduced onto the surface, so that the dispersibility and interfacial interaction ability are significantly improved; the oil field grade benzotriazole is a classic metal corrosion inhibitor with excellent adsorption performance, and can form a protective film on the metal surface; and the industrial grade sodium pyrophosphate is a water-soluble inorganic compound containing polydentate ligand groups, and has both strong metal ion complexing ability and system dispersion stability.

[0022] PEG-b-PCL reduces the interfacial tension of the system through amphiphilic structure, promotes the rapid penetration of the penetrating agent into the target medium, and builds a channel for the subsequent function; sodium gluconate chelates calcium, magnesium and other metal ions in high-salt environment, avoids precipitation reaction with other components, optimizes the dispersibility of the system, and improves the salt tolerance. The activated cellulose derivative forms a stable interfacial combination with other components by virtue of the surface active group, and constructs a three-dimensional network structure, which not only strengthens the salt tolerance stability of the system, but also locks the active components to delay the loss. In the corrosion inhibitor system, the oilfield benzotriazole builds a dense organic protective film on the surface of the metal pipe by chemical adsorption, directly blocking the contact channel of chloride ions and metal matrix; industrial-grade sodium pyrophosphate, on the one hand, complexes calcium and magnesium ions to avoid the formation of insoluble salt scale (salt scale will damage the surface integrity of the metal and accelerate the local corrosion of chloride ions), reduces the exposure of active sites on the metal surface, and reduces the adsorption and corrosion probability of chloride ions, on the other hand, complexes with metal ions to inhibit the initiation of corrosion reaction, and adjusts the pH value of the system to strengthen the stability of the protective film, and cooperates to resist the pitting and crevice corrosion dominated by chloride ions. Through the all-round cooperation of penetration promotion, salt tolerance optimization and corrosion protection of various components, long-term protection of pipe corrosion and stable play of penetration function under high-salt working conditions are realized.

[0023] In one possible implementation, the silane coupling agent is an amino silane coupling agent.

[0024] Specifically, the silane coupling agent in the present application is an amino silane coupling agent, which has both amino functional groups and siloxane groups in its molecular structure. Amino groups are strong polar groups and rich in active hydrogen atoms, and siloxane groups can undergo hydrolysis and condensation reaction in the presence of water. During the activation of cellulose derivatives, the amino silane coupling agent is chemically bonded to the hydroxyl groups on the surface of cellulose derivatives through the siloxane group, achieving firm grafting at the molecular level; at the same time, the amino groups in its molecule are exposed on the surface of cellulose derivatives, so that the modified cellulose derivatives are transformed from inert surface to functionalized materials rich in active sites, laying a structural foundation for the interaction with other components in the system.

[0025] The amino group of the amino silane coupling agent can form hydrogen bonding with the ether bond of polyethylene glycol-b-poly caprolactone, the carboxyl group of sodium gluconate, and intermolecular forces with the heterocyclic structure of benzotriazole, thereby significantly improving the compatibility of the cellulose derivative with each functional component, avoiding stratification or precipitation of the system, and enhancing the overall stability; secondly, the synergistic effect of corrosion inhibition is optimized. The strong adsorption performance of the amino group can assist the directional adsorption of benzotriazole on the metal surface, and form a synergistic complex with sodium pyrophosphate, further densifying the protective film on the metal surface and improving the resistance to chloride ions; thirdly, the salt resistance and long-term effectiveness are improved. The three-dimensional network structure of the cellulose derivative after grafting with the amino silane coupling agent is more stable, which can effectively lock the active components and reduce the loss in a high-salt environment, while inhibiting the formation of salt deposits, ensuring the long-term stability of the penetration, salt resistance, and corrosion inhibition performance; fourthly, the adaptability is strong. The hydrolysis and condensation reaction conditions of the amino silane coupling agent are mild, and the modified cellulose derivative has good compatibility with the modification process of the cellulose derivative, and the modified cellulose derivative still maintains good dispersibility, without affecting the overall permeability of the system.

[0026] The amino silane coupling agent of the present application is selected from any one of 3-aminopropyl triethoxysilane (KH-550), 3-aminopropyl trimethoxysilane (KH-540), and N-(β-aminoethyl)-γ-aminopropyl trimethoxysilane (KH-792), all with a purity of ≥98%.

[0027] In one possible implementation, the cellulose derivative is sodium carboxymethyl cellulose.

[0028] Specifically, the cellulose derivative in the present application is sodium carboxymethyl cellulose, with a particle size of 10-100 nm, a degree of substitution of 0.6-1.2, a pH value of 1% aqueous solution of 6.5-8.5, and a molecular weight of 10000-200000. Among them, sodium carboxymethyl cellulose is a water-soluble anionic polymer modified by carboxymethylation of natural cellulose, which retains the rigid skeleton of cellulose in the molecular structure and introduces a large number of carboxymethyl hydrophilic groups. Sodium carboxymethyl cellulose has high specific surface area, excellent mechanical properties of nanoscale materials, and dispersion stability of water-soluble polymers. In the penetration agent system, the carboxyl and hydroxyl groups on the molecular chain can form multiple interactions with other components, and the anionic properties of carboxymethyl groups endow them with good metal ion complexing ability and salt environment adaptability.

[0029] The water solubility and anion characteristics of sodium carboxymethyl cellulose enable it to be quickly dissolved in a dispersion medium and form a uniformly dispersed system, hinder the aggregation of itself and other components through electrostatic repulsion, avoid the stratification or precipitation of the system, and improve the overall storage and use stability of the infiltration agent. In addition, the carboxyl groups of sodium carboxymethyl cellulose can form stable complexes with calcium and magnesium ions in a high-salt environment, reducing the risk of salt scale formation and chloride ion corrosion, and forming chelation synergy with sodium gluconate and sodium pyrophosphate, thereby improving the salt tolerance of the system. Furthermore, the rigid molecular chain of sodium carboxymethyl cellulose can construct a flexible three-dimensional network structure to lock up the infiltration active components such as polyethylene glycol-b-poly caprolactone, delay their loss in a high-salt environment, and assist in the uniform adsorption of benzotriazole on the metal surface to form a dense corrosion inhibition film, thereby realizing long-acting synergy of infiltration, salt tolerance, and corrosion inhibition performance. Sodium carboxymethyl cellulose is widely available, has a mature preparation process, and has excellent compatibility with the activation and modification process of amino-based silane coupling agents. After modification, it still maintains good water solubility and dispersibility.

[0030] In one possible implementation, the dispersion medium is deionized water or simulated reservoir brine with a total salinity of ≤200,000 mg / L.

[0031] Specifically, the dispersion medium is deionized water or simulated reservoir brine with a total salinity of ≤200,000 mg / L. The deionized water reduces the interference of impurity ions, and the simulated reservoir brine reproduces the real high-salt environment by compounding common ions in oil reservoirs. Both of them have good compatibility with various functional components. The deionized water ensures the stability of the system in laboratory research and development and in low-salt conditions, and the simulated reservoir brine matches the salt tolerance threshold of the infiltration agent to fit the actual application scenarios in oilfields. The two media can provide a clean environment and ion synergy conditions for component synergy, avoid precipitation reactions caused by harmful ions, form complexation synergy with sodium gluconate and sodium pyrophosphate in the simulated reservoir brine, support the infiltration promotion of polyethylene glycol-b-poly caprolactone and the corrosion inhibition film forming effect of benzotriazole, and at the same time, expand the application range of the infiltration agent to ensure that the salt tolerance, infiltration, and corrosion inhibition performance can be stably realized under different salinity conditions.

[0032] The application also provides a preparation method of the high-salt-resistant corrosion inhibition type nano infiltration agent, which is applied to the high-salt-resistant corrosion inhibition type nano infiltration agent. Step 1, raw material pretreatment: prepare benzotriazole ethanol solution and sodium pyrophosphate aqueous solution, respectively, activate the cellulose derivative through a silane coupling agent, and mix the sodium pyrophosphate aqueous solution and sodium gluconate to obtain a mixed solution; Step 2, construction of a porous suspension: add the activated cellulose derivative into the dispersion medium, pass a small amount of nitrogen gas to form a porous structure uniform cellulose derivative suspension after ultrasonic dispersion; Step 3, component mixing: under stirring, the benzotriazole ethanol solution, the sodium pyrophosphate-sodium gluconate mixture, and the polyethylene glycol-b-poly caprolactone were sequentially added to the suspension obtained in step 2, and stirred until mixed evenly; Step 4, standing and detection: the mixed system obtained in step 3 was allowed to stand for 10 min, and the pH value was detected. When the pH value was 6.0-8.0 and the nanoparticle dispersion particle size was ≤30 nm, a qualified high-salt-resistant corrosion-resistant type nano-impregnation agent was obtained.

[0033] Specifically, in step 1, the oil field grade benzotriazole was dissolved in ethanol to prepare a uniform benzotriazole ethanol solution. It should be ensured that the benzotriazole is completely dissolved to avoid residual solid particles. The industrial grade sodium pyrophosphate was dissolved in water to prepare a sodium pyrophosphate aqueous solution, and then sodium gluconate was added. The sodium gluconate was stirred until it was completely dispersed to form a sodium pyrophosphate-sodium gluconate mixture. This process needs to ensure that the two water-soluble components are fully integrated. The cellulose derivative and 0.5% amino silane coupling agent by mass fraction were mixed and reacted under suitable conditions to graft the silane coupling agent to the surface of the cellulose derivative. After activation, it was ready for use. Through dissolution or activation, the limitation of the form of raw materials on subsequent mixing is eliminated, and preparation for efficient integration of components is made.

[0034] In step 2, deionized water or simulated reservoir brine with a total salinity of ≤200,000 mg / L was used as a dispersion medium, and the activated cellulose derivative was added. Then, an ultrasonic device was started to perform ultrasonic dispersion treatment on the mixed system. After ultrasonic dispersion, bubbling was performed. The nitrogen cylinder was connected to the gas guide pipe with a porous aeration head through a pressure reducing valve and a flow meter. The aeration head was fixed 3-5 cm below the liquid surface at the bottom of the container. The valve of the nitrogen cylinder was opened, and the pressure reducing valve and the flow meter were adjusted to control the nitrogen flow rate at 5-10 mL / min to make the aeration head generate micro-bubbles with a diameter of 0.5-1 mm. Low-speed stirring was maintained at 50-100 rpm during the bubbling process to avoid bubble aggregation. After continuous bubbling, the nitrogen was turned off. Through the generation, slow rising, and escape of micro-bubbles, a uniform porous structure was formed in the suspension, and finally a cellulose derivative suspension with stable porous structure was obtained.

[0035] In step 3, the benzotriazole ethanol solution prepared in step 1 was slowly added to the porous suspension of step 2, and stirred for 1-2 minutes for preliminary dispersion. Then, the sodium pyrophosphate-sodium gluconate mixture was added, and the system was continuously stirred until it was evenly mixed. Finally, the polyethylene glycol-b-poly caprolactone was added, and the stirring was continued until the block copolymer was completely dissolved and integrated with the system. When adding the polyethylene glycol-b-poly caprolactone, the system temperature needs to be controlled at 25-30°C.

[0036] Step 4, place the container containing the product of step 3 on the shockproof experimental bench, and stand for 10 minutes to allow the small air bubbles entrained in the mixing process to slowly rise and escape, and at the same time allow the very fine impurity particles to fully settle to the bottom of the container. After standing, a sterile glass sampler with a volume of 5-10 mL is selected, and the sampler needle is slowly inserted into the middle of the system along the inner wall to the middle position between the liquid surface and the bottom of the container before sampling. 2-3 mL of sample is slowly drawn to avoid bringing in the bottom sediment or surface bubbles during sampling. Then detection is carried out. During the detection process, first rinse the pH meter probe with deionized water, then insert it into the sample after wiping off the surface moisture with filter paper. After the reading is stable (usually 30 seconds-1 minute), record the pH value. At the same time, 1 mL of sample is taken and injected into the special cuvette of the particle size analyzer. After ensuring that the sample is free of air bubbles, it is placed into the instrument and the nanoparticle detection mode is selected for measurement. If the detection results show that the pH value is between 6.0-8.0 and the nanoparticle dispersion particle size is ≤30 nm, the system is directly transferred to a sealed storage tank to obtain the qualified product. If the pH value is too low, a small amount of 0.1 mol / L sodium hydroxide solution can be added for adjustment. If the pH value is too high, a small amount of 0.1 mol / L hydrochloric acid solution can be added. If the particle size exceeds the standard, return to step 2 and re-disperse by ultrasonic. Adjust the parameters and complete the subsequent steps again until the indicators meet the requirements to ensure that the final product meets the use requirements.

[0037] In one possible implementation, in step 1, the preparation process of the benzotriazole ethanol solution is as follows: take the formula amount of oil field grade benzotriazole, add 3-5 times the mass of industrial ethanol, and stir at 25-30°C for 10-15 min until completely dissolved. The preparation process of the sodium pyrophosphate aqueous solution is as follows: take the formula amount of industrial grade sodium pyrophosphate, add 8-10 times the mass of 30°C warm water, and stir for 5-8 min until fully dissolved.

[0038] Specifically, the preparation of the benzotriazole ethanol solution: weigh the formula amount of oil field grade benzotriazole with a purity of ≥98%, slowly pour into a conical flask, and add industrial ethanol with a purity of ≥95% and a water content of ≤5% at a mass of 3-5 times that of the benzotriazole. Slowly inject along the glass rod to avoid splashing. Put a clean stirrer in the bottle, place it in a constant temperature water bath and adjust the temperature to 25-30°C. Use a precision 0.1°C thermometer to confirm that the solution temperature is consistent with the water bath, then stir at a speed of 250-300 rpm for 10-15 min, and observe every 2 min until the solution is uniform and transparent without solid residue, i.e. completely dissolved. If not dissolved, extend the stirring time by 2-3 min or check the ethanol purity and water temperature. After dissolution, close the equipment, seal with a lid, and store for use to prevent ethanol evaporation.

[0039] Preparation of aqueous sodium pyrophosphate solution: take the formula amount of industrial grade sodium pyrophosphate with purity ≥96% into a standby beaker, and then preheat the deionized water to be stable at 30℃±1℃. Measure the warm water with 8~10 times the mass of sodium pyrophosphate, and pour it into the beaker. Confirm the solution temperature with a thermometer to be 28~32℃. Insert the stirring paddle into the middle of the solution (1~2 cm from the bottom of the beaker), and stir at a speed of 150~200 rpm for 5~8 min. Observe the solution every 1 min. If the solution is colorless, transparent, and free of precipitates and clumps, it is fully dissolved. If there are local clumps, you can help disperse them by gently turning the beaker. After dissolving, turn off the stirring, and place the solution in a 30℃ water bath for preservation to prevent temperature drop and precipitation.

[0040] In one possible implementation, in step 1, the cellulose derivative is sodium carboxymethyl cellulose, and the silane coupling agent is an amino silane coupling agent. The process of activating the cellulose derivative with the silane coupling agent is as follows: Take the formula amount of cellulose derivative, and add 5~8 times its mass of deionized water. Under the conditions of power 180~220 W and frequency 25 kHz, ultrasonically create pores for 15~20 min. Then add a silane coupling agent solution with a mass fraction of 0.5%, and stir at 35~40℃ for 20~30 min to complete the activation process. The amount of silane coupling agent solution is 10~15 times the mass of the cellulose derivative. After activation, filter and wash with deionized water 2~3 times to remove excess silane coupling agent. After activation, detect the specific surface area of the cellulose derivative to ensure that the specific surface area of the cellulose derivative is greater than or equal to 150 m 2 / g.

[0041] Specifically, the sodium carboxymethyl cellulose powder is weighed according to the formula, and the first-grade and above deionized water with a mass of 5-8 times that of the sodium carboxymethyl cellulose powder is measured and poured into a three-necked flask with a mechanical stirring paddle and a thermometer interface. Then, the ultrasonic pore forming treatment is carried out. The stirrer is started at a speed of 200-300 r / min to slowly add the sodium carboxymethyl cellulose powder into the water along the stirring direction to avoid accumulation. After the powder is completely added, the stirring speed is increased to 300-400 r / min, and the uniform suspension is formed after 5 min of pre-stirring. Then, the flask is fixed on the ultrasonic generator, and the ultrasonic probe is immersed in the suspension. The power is set to 180-220 W, and the frequency is set to 25 kHz. The ultrasonic pore forming is performed for 15-20 min. The temperature is monitored in real time during the process. If the temperature exceeds 40℃, the process is paused for 1-2 min to cool down. The state of the suspension is observed every 5 min to ensure that there is no obvious precipitation. After the ultrasonic treatment, the stirring is maintained for standby. Finally, the amino silane coupling agent activation reaction is carried out. The three-necked flask containing the dispersion liquid after the ultrasonic treatment is placed in a constant temperature water bath, and the temperature is increased to 35-40℃ and stabilized for 10 min. The stirring speed is maintained at 300-400 r / min, and the prepared coupling agent solution is slowly added into the dispersion liquid through a constant pressure dropping funnel. After the addition is completed, the constant temperature stirring is continued at the temperature for 20-30 min to ensure that the reaction is fully carried out to complete the activation. After the reaction is completed, the relevant equipment is turned off and the system is left for 5 min.

[0042] After the above activation reaction and standing steps are completed, the activated product needs to be immediately separated, washed and quality detected to ensure that it meets the use requirements of the subsequent infiltration agent preparation. During the product separation and washing, the reaction system after activation is first transferred to a Buchner funnel, and solid-liquid separation is realized by vacuum filtration. The filter cake is collected and re-dispersed with an appropriate amount of deionized water. After uniform stirring, vacuum filtration is performed again. This washing process is repeated 2-3 times to completely remove the unreacted coupling agent and reaction by-products remaining on the surface of the filter cake. After each washing operation is completed, a small amount of washing filtrate can be taken for detection until no coupling agent residue is detected in the filtrate, which is considered as qualified washing. The core index of quality detection is the specific surface area, and the specific operation is as follows: the washed and qualified filter cake is placed in a vacuum drying oven and dried at 55-65℃ and -0.1 to -0.08 MPa until the mass is constant. The dried sample is placed in a special sample tube. First, the sample is degassed at a temperature of 90-110℃ for 1.5-2.5 h to remove the impurities and water adsorbed on the surface of the sample. Then, the BET method (liquid nitrogen adsorption-desorption method) is used to measure the specific surface area. To ensure the accuracy of the data, the detection process needs to be repeated 3-5 times and the average value is taken. If the final detection result shows that the specific surface area of the sample is ≥150 m² / g, it means that the activated product meets the quality standard and can be used for the preparation of the subsequent high-salt-resistant and corrosion-inhibiting type nano-infiltration agent. If the specific surface area does not meet the requirement, the ultrasonic power, ultrasonic time or coupling agent dosage and other key conditions need to be adjusted according to the actual experimental situation to re-activate the cellulose derivative.

[0043] In a possible implementation, in step 2, the ultrasonic dispersion parameters are power 200-300 W, frequency 20-25 kHz, and dispersion time 20-30 min; the nitrogen bubbling flow rate is 5-10 mL / min, and the bubbling time is 15-20 min.

[0044] Specifically, the ultrasonic dispersion parameters are set as power 200-300 W, frequency 20-25 kHz, and dispersion time 20-30 min; this parameter range can make the material particles in the system fully fragmented and uniformly dispersed through moderate ultrasonic energy impact, avoid particle agglomeration, and at the same time, prevent the material structure from being damaged due to excessive energy; nitrogen bubbling is performed at a flow rate of 5-10 mL / min for 15-20 min, which can further strengthen the material dispersion effect through the stirring action of nitrogen, isolate air through the nitrogen atmosphere to prevent the material from being oxidized and deteriorated during the dispersion process, and timely remove the trace bubbles and volatile impurities generated during ultrasonic dispersion, thereby ensuring the uniformity and stability of the dispersion system and laying a foundation for the smooth progress of the subsequent reaction and the improvement of the product performance.

[0045] In a possible implementation, in step 3, the stirring speed after adding the benzotriazole ethanol solution is 300-500 r / min, and the stirring time is 15-20 min; the stirring is continued for 10 min after adding the mixed solution; after adding the polyethylene glycol-b-poly caprolactone, the stirring speed is increased to 600-800 r / min, and the stirring time is 25-30 min.

[0046] Specifically, after adding the benzotriazole ethanol solution, the stirring is performed at a speed of 300-500 r / min for 15-20 min, which can ensure that the solution and the system are fully mixed to make the benzotriazole uniformly dispersed and initially play the pre-formation effect of the corrosion inhibitor component, and at the same time, avoid excessive bubbles in the system due to excessive stirring speed; the stirring is continued for 10 min after adding the mixed solution, which can make the newly added materials quickly integrate with the existing system and maintain the stability of the system. After adding the polyethylene glycol-b-poly caprolactone, the stirring speed is increased to 600-800 r / min and the stirring time is 25-30 min, which can break the local aggregation of the polyethylene glycol-b-poly caprolactone, promote the grafting of the polyethylene glycol-b-poly caprolactone on the surface of the cellulose derivative, and extend the stirring time to ensure the grafting reaction to be more complete. The gradient setting of the entire stirring parameters can realize the orderly dispersion and reaction of the components and at the same time, ensure that the final product has good corrosion inhibition performance and dispersion stability, thereby providing a guarantee for the application of the osmotic agent in a high-salt environment. When the polyethylene glycol-b-poly caprolactone is added, the temperature of the system needs to be controlled at 25-30℃.

[0047] The application further provides a use of the high-salt-resistant corrosion inhibition type nano osmotic agent in oil and gas exploitation.

[0048] Specifically, after the high-salt-resistant corrosion-inhibiting nano-impregnating agent in the application is injected into the oil and gas reservoir through the liquid injection process, on the one hand, the active components in the nano level can penetrate into the reservoir pores and micro-cracks by means of impregnation, reduce the oil-water interfacial tension to promote the stripping and flow of crude oil, and improve the oil and gas recovery rate; on the other hand, the corrosion-inhibiting components contained therein can form a dense protective film on the surface of metal equipment such as pumping rods and oil pipes to inhibit electrochemical corrosion in a high-salt environment, reduce equipment wear and maintenance costs, and at the same time, the impregnating agent itself has excellent salt resistance and stability and is not easy to be inactivated in high-mineralization formation water, and can play a dual role of impregnation oil extraction and corrosion protection for a long time, thereby providing protection for the efficiency and safety of oil and gas exploitation.

[0049] The application is further illustrated by the following examples.

[0050] 1. Raw materials Polyethylene glycol-b-poly caprolactone: 50 g, molecular weight 5000-10000, PEG / PCL block ratio 1:1; wherein PEG is polyethylene glycol and PCL is poly caprolactone; Sodium gluconate: 40 g, industrial grade, purity ≥98%; Sodium carboxymethyl cellulose: 40 g, degree of substitution 0.8-1.0; Oil field grade benzotriazole: 1.5 g, purity ≥95%; Industrial grade sodium pyrophosphate: 3 g, purity ≥96%; Simulated reservoir brine: 365.5 g, total salinity 200000 mg / L (containing Cl - 100000 mg / L, Ca 2+ 8000 mg / L, Mg 2+ 5000 mg / L) Auxiliary materials: industrial ethanol 6 g, 0.5% amino silane coupling agent solution 480 g, and the amino silane coupling agent is KH-550 with a purity of ≥98%.

[0051] 2. Experimental equipment Ultrasonic cell disruptor (0-300 W, 20-25 kHz), electric stirrer (0-1000 r / min); Vacuum filtration device, vacuum drying oven (0-200℃), nitrogen cylinder (with flowmeter); Electronic balance (accuracy 0.001 g), constant temperature water bath (temperature control ±0.5℃), zeta potential instrument, rotary viscometer (0-1000 mPa·s), surface tension instrument, and self-impregnation instrument.

[0052] 3. Example-preparation process Step 1: raw material pretreatment 1.1. Preparation of benzotriazole solution: 1.5 g of benzotriazole was dissolved in 6 g of industrial ethanol, stirred at 28°C for 12 min until completely transparent, and ready for use.

[0053] 1.2. Preparation of chelating mixed solution: 3 g of sodium pyrophosphate was dissolved in 27 g of warm water at 30°C, stirred for 5 min, then 40 g of sodium gluconate was added, and stirred for 8 min until dissolved, and ready for use.

[0054] 1.3. Activation of sodium carboxymethyl cellulose: 40 g of sodium carboxymethyl cellulose was added to 240 g of deionized water, pre-stirred for 10 min to form a suspension; 200 W, 25 kHz ultrasonic pore forming for 18 min; the temperature during ultrasonic process did not exceed 40°C. Under constant temperature water bath at 38°C, 480 g of 0.5% amino silane coupling agent solution was added dropwise, and stirred for 25 min; after suction filtration, it was washed with deionized water for 3 times, and vacuum dried at 60°C until constant weight, and the specific surface area was ≥150 m 2 / g.

[0055] Step 2: Construction of porous suspension 365.5 g of simulated oil reservoir brine was poured into a container, and the activated sodium carboxymethyl cellulose was slowly added; the ultrasonic cell disrupter (250 W, 22 kHz) was started, and ultrasonic dispersion was performed for 25 min; then a nitrogen gas sparging head was placed 3 cm below the liquid surface, and nitrogen gas was bubbled at a flow rate of 8 mL / min for 18 min to form a uniform porous suspension.

[0056] Step 3: Gradient mixing of components 3.1. Under stirring at 400 r / min, the benzotriazole solution was slowly added, and the stirring speed was maintained for 18 min.

[0057] 3.2. The chelating mixed solution was added at the same stirring speed, and stirred for 10 min.

[0058] 3.3. 50 g of polyethylene glycol-b-poly caprolactone was added, the stirring speed was increased to 700 r / min, and stirring was performed at 25-30°C for 28 min until complete dissolution.

[0059] Step 4: Quality control and determination of finished product The mixed system was transferred to a sealed container, and left to stand for 10 min to remove entrained bubbles; the sample was taken from the middle of the container for detection: pH value 7.2; nanoparticle dispersion particle size 18 nm, both indicators met the standards, and it was a qualified infiltration agent.

[0060] 4. Detection index (at 60°C) 4.1. High salt stability: including system basic stability and infiltration function stability; 4.1.1. System stability: The initial dispersed particle size, 72h particle size change rate, zeta potential, viscosity change, and stratification after standing were measured. The requirements are: particle size change rate ≤20%, absolute value of zeta potential ≥30mV, viscosity change rate ≤15%, and no stratification. 4.1.2. Stable Irradiation Function: Initial and 72-hour surface tension, interfacial tension, and self-absorption height were measured. Surface tension was required to be ≤35 mN / m, interfacial tension ≤1.5 mN / m, and the rate of change in self-absorption height ≤10%. Testing methods: Basic stability: A 50 mL sample was placed at 60℃ and allowed to stand. Particle size, potential, and viscosity were measured at 0 h and 72 h. Functional stability: Surface tension was measured using the ring method, interfacial tension using the pendant drop method, and self-absorption height (cumulative value over 72 h) was measured using a self-absorption analyzer (natural core, φ25 mm × 50 mm).

[0061] 4.2. Permeation efficiency: Displacement experiments were conducted using natural rock cores (specifications φ25mm×50mm, porosity 18%~22%, permeability 100~200mD). The "increase in core permeation recovery rate" was used as the indicator, and the requirement was ≥15%.

[0062] 4.3. Corrosion Inhibition Performance: 1. Material Selection: 20CrMo steel was used. 2. Testing Method: The loss-in-weight method was used. The specific steps were as follows: Take a 20CrMo steel sample (20mm×10mm×2mm), polish it sequentially with 400#, 800#, and 1200# sandpaper, degrease it with anhydrous ethanol for 10 minutes, rinse it with deionized water, dry it, and weigh it accurately (recorded as m1, with an accuracy of 0.001g); immerse the sample completely in simulated reservoir brine containing 5% of the percolating agent from the example, and corrode it at a constant temperature of 60℃ and 150r / min for 72 hours; remove the sample and remove it with a rust remover (5% lemon juice). Soak in acid + 0.5% thiourea for 3-5 minutes to remove corrosion products (visually judged by the absence of rust spots), then degrease with anhydrous ethanol, rinse with deionized water, blow dry and weigh (recorded as m2); corrosion rate and corrosion inhibition rate are calculated as follows: corrosion rate v = (m1-m2) × 87600 / (S × t × ρ) (S is the surface area of ​​the test piece, t is the corrosion time, ρ is the steel density 7.85 g / cm³), corrosion inhibition rate η = (v0-v1) / v0 × 100% (v0 is the corrosion rate of blank brine, v1 is the corrosion rate of the sample).

[0063] 3. Standard requirements: corrosion rate ≤ 0.1 mm / a, corrosion inhibition rate ≥ 85%.

[0064] 5. Test Results The results of each performance test index are shown in Table 1: Table 1 Test Results Detection index Unit Detection value Standard requirement Initial dispersed particle size nm 18 ≤ 30 nm Dispersed particle size after 72 h nm 21 - Particle size change rate % 16.7 ≤20% Zeta potential after 72 h mV -35.2 Absolute value ≥ 30 mV Initial viscosity (60°C) mPa·s 85 - Viscosity after 72 h (60°C) mPa·s 78 - Viscosity change rate % 8.2 ≤15% Oil-water interfacial tension mN / m 0.9 (RSD = 2.1%) ≤ 1.5 mN / m, RSD ≤ 3% Core recovery rate improvement range % 22.3 ≥15% Corrosion rate of 20CrMo steel (sucker rod steel) mm / a 0.072 ≤ 0.1 mm / a Corrosion inhibition rate % 88.7 ≥85% 72 h standing stratification - No stratification, uniform and stable No stratification 6. Blank test verification (corrosion inhibition performance) To eliminate the interference of the inherent corrosion resistance of 20CrMo steel on the test results, a blank control group was set up for comparison with the experimental group to verify the corrosion inhibition and synergistic effect of the penetrant. The specific design and results are as follows: 6.1. Experimental design: Both groups used simulated reservoir brine (total salinity 200,000 mg / L) as the corrosive medium and underwent constant temperature oscillation corrosion at 60℃ and 150 r / min for 72 h; the experimental group contained 5% of the permeate from the example, while the blank group contained no permeate component, and all other conditions were completely identical.

[0065] 6.2. Test materials and pretreatment: Both groups used 20CrMo steel test pieces (20mm×10mm×2mm), which were polished with 400# / 800# / 1200# sandpaper, degreased with anhydrous ethanol for 10 min, rinsed with deionized water, dried and weighed (the experimental group was recorded as m1 and the blank group as m0).

[0066] 6.3. Data Results: After corrosion and the same post-treatment, the corrosion rate of the blank group was v0=0.637mm / a, and the corrosion rate of the experimental group was v1=0.072mm / a. The corrosion inhibition rate was calculated to be 88.7% using the formula η=(v0-v1) / v0×100%, which proves the corrosion protection and strengthening effect of the penetrant on 20CrMo steel.

[0067] 7. Conclusion Based on the test results, the high-salt resistant corrosion-inhibiting nano-permeabilizer prepared using the proposed method fully meets the performance requirements of high-salt reservoir extraction, and the preparation process has industrialization potential. Regarding high-salt stability, the permeabilizer initially disperses at 18 nm, increasing to 21 nm after 72 hours, with a particle size change rate of only 16.7%. Its zeta potential reaches -35.2 mV, and its initial viscosity is 85 mPa·s, increasing to 78 mPa·s after 72 hours, with a viscosity change rate of 8.2%. It exhibits no stratification and remains homogeneous and stable after standing for 72 hours in a high-salt environment at 60℃, making it suitable for harsh reservoir environments. In terms of permeation and oil displacement performance, its oil-water interfacial tension is as low as 0.9 mN / m (relative standard deviation 2.1%), and its core recovery rate increases by 22.3%, significantly exceeding the target, effectively reducing oil-water interfacial resistance and improving crude oil extraction efficiency. It exhibits outstanding corrosion inhibition and protection performance, with a corrosion rate of only 0.072 mm / a for 20CrMo steel commonly used in sucker rods, and a corrosion inhibition rate of 88.7%, effectively reducing corrosion losses of downhole equipment. Therefore, this penetrant and its preparation method provide a reliable guarantee for large-scale production and field application.

[0068] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A high salt resistant corrosion inhibition type nano-impregnation agent, characterized in that, By weight percentage, including: 8~12% polyethylene glycol-b-poly (caprolactone), 5~10% sodium gluconate, 5~10% nanoscale cellulose derivatives, 0.3% oil field level benzotriazole, 0.6% industrial grade sodium pyrophosphate, the balance is a dispersion medium, the sum of the weight percentage of each component is 100%; The cellulose derivative is a cellulose derivative activated by 0.5% mass fraction silane coupling agent.

2. The high-salt-tolerant corrosion-inhibiting nano-impregnant according to claim 1, characterized in that, The silane coupling agent is an amino silane coupling agent. 3.The high-salt-tolerant corrosion-inhibiting nano-impregnating agent according to claim 1, characterized in that, The cellulose derivative is sodium carboxymethyl cellulose. 4.The high-salt-tolerant corrosion-inhibiting nano-impregnating agent according to claim 1, characterized in that, The dispersion medium is deionized water or simulated reservoir brine with total salinity ≤200000 mg / L.

5. A method for preparing a high-salt-resistant corrosion-inhibiting nano-impregnant, characterized in that, Applied to the high-salt-resistant corrosion-resistant nano-imbibition agent of any one of claims 1-4, comprising the following steps: Step 1, raw material pretreatment: prepare benzotriazole ethanol solution, sodium pyrophosphate aqueous solution, and activate the cellulose derivative by silane coupling agent, mix the sodium pyrophosphate aqueous solution with sodium gluconate to obtain a mixed solution; Step 2, construct a porous suspension: add the activated cellulose derivative to the dispersion medium, disperse by ultrasound, and then introduce a small amount of nitrogen gas to form a uniform porous cellulose derivative suspension; Step 3, component mixing: under stirring, add benzotriazole ethanol solution, sodium pyrophosphate-sodium gluconate mixed solution and polyethylene glycol-b-poly (caprolactone) to the suspension obtained in step 2 in sequence, and stir until mixed evenly; Step 4, standing and detection: the mixed system obtained in step 3 is allowed to stand for 10 min, and the sample is detected for pH value of 6.0~8.0 and nanoparticle dispersion particle size ≤30 nm, to obtain a qualified high-salt-resistant corrosion-resistant nano-imbibition agent.

6. The method for preparing the high-salt-resistant corrosion-inhibiting nano- wetting agent according to claim 5, characterized in that, In step 1, the preparation process of benzotriazole ethanol solution is as follows: take the formula amount of oil field level benzotriazole, add 3~5 times its mass of industrial ethanol, and stir at 25~30℃ for 10~15 min until completely dissolved; The preparation process of sodium pyrophosphate aqueous solution is as follows: take the formula amount of industrial grade sodium pyrophosphate, add 8~10 times its mass of 30℃ warm water, and stir for 5~8 min until completely dissolved.

7. The method for preparing the high-salt-resistant corrosion-inhibiting nano- wetting agent according to claim 5, characterized in that, In step 1, the cellulose derivative is sodium carboxymethyl cellulose, and the silane coupling agent is an amino silane coupling agent. The process of activating the cellulose derivative by the silane coupling agent is as follows: Take the formula amount of sodium carboxymethyl cellulose, add 5~8 times its mass of deionized water, and ultrasonically pore-forming at a power of 180~220 W and a frequency of 25 kHz for 15~20 min. Then add 0.5% amino silane coupling agent solution, and stir at 35~40℃ for 20~30 min to complete the activation process. The amount of amino silane coupling agent is 10~15 times the mass of sodium carboxymethyl cellulose; After activation, filtration, washing with deionized water 2-3 times to remove excess amino silane coupling agent, and after activation, the carboxymethylcellulose sodium specific surface area is measured to ensure that the cellulose derivative specific surface area is greater than or equal to 150 m 2 / g.

8. The method for preparing the high-salt-resistant corrosion-inhibiting nano- wetting agent according to claim 5, characterized in that, In step 2, the ultrasonic dispersion parameters are power 200~300 W, frequency 20~25 kHz, and dispersion time 20~30 min. The nitrogen bubbling flow is 5~10 mL / min, and the bubbling time is 15~20 min.

9. The method for preparing the high-salt-resistant corrosion-inhibiting nano- wetting agent according to claim 5, characterized in that, In the step 3, the stirring speed after adding the benzotriazole ethanol solution is 300-500 r / min, the stirring time is 15-20 min; after adding the mixed solution, continue to stir for 10-15 min; after adding the polyethylene glycol-b-poly caprolactone, the stirring speed is increased to 600-800 r / min, and the stirring time is 25-30 min.

10. The use of the high-salt-resistant corrosion-inhibiting nano-impregnating agent according to any one of claims 1-4 in oil and gas exploitation.

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