Nano-silicon-loaded para-phenolic aldehyde pre-polymerization cross-linking agent as well as preparation method and application thereof

Abstract

The invention relates to the technical field of oil field plugging, and discloses a nano-silicon-loaded para-phenolic aldehyde prepolymerization cross-linking agent as well as a preparation method and application thereof. The method comprises the following steps: (1) reacting hydroquinone, ethylenediamine, silane coupling agent modified nano silicon oxide and a dispersion stabilizer under an alkaline condition to obtain a first reaction solution; (2) reacting the first reaction solution with part of hexamethylenetetramine to obtain a second reaction solution; and (3) carrying out a reaction on the second reaction solution and the rest of hexamethylenetetramine. The nano-silicon-loaded para-phenolic aldehyde prepolymerization cross-linking agent is high in gelling strength and high in aging stability under the ultrahigh-temperature and high-salt conditions, and phenolic aldehyde gel prepared from the nano-silicon-loaded para-phenolic aldehyde prepolymerization cross-linking agent has good structural stability, rheological property and reservoir large pore channel plugging performance under the ultrahigh-temperature and high-salt conditions.

Description

Technical Field

[0001] This invention relates to the field of oilfield plugging technology, specifically to a nano-silicon-supported para-phenolic prepolymer crosslinking agent, its preparation method, and its application. Background Technology

[0002] Phenolic crosslinking agents are a class of synthetic polymer materials that have attracted widespread attention due to their low cost, ease of preparation, and excellent thermal stability, rigidity, solubility, and flame retardant properties. They have been widely used in various fields such as oilfield water shut-off agents, adhesives, and flame retardants. Phenolic gels are typically produced by polymerizing phenols and formaldehyde to obtain phenolic prepolymers, which are then crosslinked with polymers at certain temperatures to form a viscoelastic with a three-dimensional network structure. The crosslinking density and crosslinking strength significantly affect the network structure and physical properties of the gel. Furthermore, the performance of phenolic gels directly relates to the effective period of water shut-off in oilfields. Long-term effective phenolic gels are beneficial for effectively preventing water channeling in oil wells and improving oil well development efficiency. Phenolic gels have low viscosity, are easy to inject, and can preferentially enter the formation's dominant seepage channels. After injection into the formation, they gradually solidify into gels at formation temperatures, thereby sealing water channeling channels, improving water drive sweep efficiency, and ultimately increasing oil recovery. However, gels prepared using phenolic crosslinking agents experience a significant decrease in gel strength and stability under high-temperature and high-salinity formation conditions, and therefore lack the ability to seal water channeling channels for extended periods. Therefore, it is particularly urgent to enhance the high temperature and high salt tolerance of phenolic gels and improve their sealing effect in high temperature and high salt reservoirs. Summary of the Invention

[0003] The purpose of this invention is to overcome the problems of poor gel strength and long-term sealing stability of phenolic gels in existing technologies, as well as poor resistance to high temperature and high salt, which leads to a decrease in oil recovery rate during crude oil extraction. This invention provides a nano-silicon-supported para-phenolic prepolymer crosslinking agent. Phenolic gels prepared using this nano-silicon-supported para-phenolic prepolymer crosslinking agent exhibit good gel strength and resistance to high temperature and high salt. Its application in crude oil extraction can significantly improve the sealing rate and stability, thereby increasing the oil recovery rate.

[0004] To achieve the above objectives, the present invention provides a method for supporting a nano-silicon-based para-phenolic prepolymer crosslinking agent, the method comprising the following steps: (1) Under alkaline conditions, hydroquinone, ethylenediamine, silane coupling agent modified nano-silica and dispersant stabilizer are reacted to obtain the first reaction solution; (2) The first reaction solution and a portion of hexamethylenetetramine are reacted to obtain the second reaction solution; (3) React the second reaction solution with the remaining hexamethylenetetramine; Based on the total weight of hexamethylenetetramine used in steps (2) and (3), the amount of hexamethylenetetramine used in step (2) is 50-70% by weight, and the amount of hexamethylenetetramine used in step (3) is 30-50% by weight. The reaction temperature in step (3) is 5-20°C higher than the reaction temperature in step (2); In step (1), the silane coupling agent is KH560.

[0005] Preferably, in step (1), the dispersant stabilizer is selected from one or more of silicates, sodium hexametaphosphate and sodium dodecylbenzenesulfonate.

[0006] Preferably, in step (1), the particle size of the silane coupling agent modified nano-silica is 10-100 nm.

[0007] Preferably, in step (1), the molar ratio of hydroquinone to ethylenediamine is 1:0.03-0.07.

[0008] Preferably, in step (1), the weight ratio of hydroquinone to silane coupling agent modified nano-silica is 20:0.1-0.2.

[0009] Preferably, in step (1), the weight ratio of hydroquinone to the dispersant stabilizer is 20:0.1-0.2.

[0010] Preferably, in step (1), the reaction conditions include: a temperature of 120-160℃ and a time of 14-20h.

[0011] Preferably, the molar ratio of the amount of hydroquinone to the total amount of hexamethylenetetramine used in steps (2) and (3) is 1:0.5-1.5.

[0012] Preferably, in step (2), the reaction conditions include: a temperature of 70-85°C and a time of 3-4 hours.

[0013] Preferably, in step (3), the reaction conditions include: a temperature of 80-90°C and a time of 4-6 hours.

[0014] A second aspect of the present invention provides a nano-silicon-supported para-phenolic prepolymer crosslinking agent prepared by the above method.

[0015] A third aspect of the present invention provides a nano-silicon-supported para-phenolic gel, wherein the nano-silicon-supported para-phenolic gel contains a functional polymer and the above-mentioned nano-silicon-supported para-phenolic prepolymer crosslinking agent.

[0016] Preferably, the weight ratio of the functional polymer to the nano-silicon-supported para-phenolic prepolymer crosslinking agent is 1:3-8.

[0017] Preferably, the functional polymer is a copolymer of acrylamide monomers and sulfonic acid monomers.

[0018] Preferably, the weight-average molecular weight of the functional polymer is 10 million to 20 million.

[0019] The fourth aspect of this invention provides the application of the above-mentioned nano-silicon-supported para-phenolic gel in the crude oil extraction process of high-temperature and high-salinity oil reservoirs.

[0020] Preferably, the application process includes: first injecting the functional polymer into the formation, then injecting the nano-silicon-supported para-phenolic prepolymer crosslinking agent, and then aging.

[0021] Compared with the prior art, the technical solution of the present invention has the following advantages: The present invention describes a nano-silicon-supported para-phenolic prepolymer crosslinking agent using silane coupling agent-modified nano-silica as a rigid nanofiller. In phenolic gels prepared using this nano-silicon-supported para-phenolic prepolymer crosslinking agent, the nano-silicon-supported para-phenolic prepolymer crosslinking agent acts as a "physical crosslinking point" in the system, filling the polymer network, enhancing the density and strength of the network structure, reducing porosity, partially absorbing and dispersing external heat, reducing the damage to the polymer backbone caused by high temperatures, thereby improving mechanical properties, reducing ion penetration, and effectively improving the gel's salt resistance. Furthermore, the silane coupling agent-modified nano-silica combines nano-silicon with the para-phenolic crosslinked prepolymer structure through epoxy group ring-opening, resulting in a large amount of crosslinking covering the surface of the nano-silicon material. The functional groups, including a large number of hydroxymethyl and amide groups on the surface of nano-silicon, dehydrate and condense to form a more stable network structure. The nano-silicon is firmly "anchored" in the three-dimensional network structure, forming a three-dimensional network structure with higher cross-linking density and higher mechanical strength, thereby improving the water retention stability and strength stability of the prepared phenolic gel under high temperature and high salt conditions. In addition, the nano-silicon material is covalently bonded to the phenolic gel, which enhances its dispersion performance in the network skeleton. The uniformly dispersed nano-silicon under high temperature and high salt conditions can form a "nano barrier" in the gel, which can hinder the migration of water molecules and salt ions in the gel network, slow down the degradation rate, and play a long-term role in improving the heterogeneity of high temperature and high salt reservoirs, improving the subsequent water drive sweep efficiency, and thus improving the crude oil recovery rate. Attached Figure Description

[0022] Figure 1 This is the infrared spectrum of the nano-silicon-supported para-phenolic prepolymer crosslinking agent prepared in Example 1 of this invention; Figure 2 This is an image showing the appearance morphology of the nano-silicon-supported para-phenolic gel prepared in Example 1 of this invention; Figure 3 This is a graph showing the change in injection pressure before and after core plugging of the nano-silicon-supported para-phenolic prepolymer crosslinking agent prepared in Example 1 of this invention during the testing process. Detailed Implementation

[0023] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0024] 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.

[0025] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating relative importance or implying the number of technical features indicated. Therefore, unless otherwise stated, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature; "multiple" means two or more. The term "comprising" and any variations thereof mean non-exclusive inclusion, where one or more other features, integers, steps, operations, units, components, and / or combinations thereof may be present or added.

[0026] This invention provides a method for supporting a nano-silicon-based para-phenolic prepolymer crosslinking agent, the method comprising the following steps: (1) Under alkaline conditions, hydroquinone, ethylenediamine, silane coupling agent modified nano-silica and dispersant stabilizer are reacted to obtain the first reaction solution; (2) The first reaction solution and a portion of hexamethylenetetramine are reacted to obtain the second reaction solution; (3) React the second reaction solution with the remaining hexamethylenetetramine; Based on the total weight of hexamethylenetetramine used in steps (2) and (3), the amount of hexamethylenetetramine used in step (2) is 50-70% by weight, and the amount of hexamethylenetetramine used in step (3) is 30-50% by weight. The reaction temperature in step (3) is 5-20°C higher than the reaction temperature in step (2); In step (1), the silane coupling agent is KH560.

[0027] In the method described in this invention, in step (1), hexamethylenetetramine decomposes into formaldehyde and ammonia at a specific temperature, hydroquinone reacts with formaldehyde to obtain a phenolic prepolymer, and under the action of a dispersing stabilizer, the silane coupling agent modified nano-silica is uniformly dispersed and physically crosslinks with the phenolic prepolymer. Simultaneously, the epoxy groups of the silane coupling agent are opened by the catalyst ethylenediamine, chemically crosslinking the silane coupling agent modified nano-silica with the para-phenolic prepolymer, thus loading the silane coupling agent modified nano-silica onto the phenolic prepolymer to obtain a first reaction solution; in step (2), the first reaction solution is reacted with a portion of hexamethylenetetramine to initially achieve three-dimensional network crosslinking, obtaining a second reaction solution; In step (3), the second reaction solution is reacted with the remaining hexamethylenetetramine to achieve further three-dimensional network crosslinking, thereby obtaining a nano-silicon-supported para-phenolic prepolymer crosslinking agent. Based on this, the method described in this invention uses silane coupling agent to modify nano-silica as a rigid filler to construct a denser spatial network, exhibiting stronger gelling performance and viscoelastic properties. At the same time, by reacting with hexamethylenetetramine in steps and controlling the reaction temperature difference between the two steps, the phenolic gel formed by the nano-silicon-supported para-phenolic prepolymer crosslinking agent and the polymer has good anti-deformation properties and gelling strength. When used in the oilfield exploitation process, it has good permeability and long-term stability, thereby improving the plugging rate and oilfield recovery rate.

[0028] In a preferred embodiment, in order to further improve the high temperature and high salt resistance of the nano-silicon-supported para-phenolic prepolymer crosslinking agent, in step (1), the dispersing stabilizer is selected from one or more of silicates, sodium hexametaphosphate and sodium dodecylbenzenesulfonate; preferably silicates.

[0029] In a preferred embodiment, in step (1), the particle size of the silane coupling agent modified nano-silica is 10-100 nm.

[0030] In one specific embodiment, the silane coupling agent modified nano-silica is prepared by mixing the above-mentioned silane coupling agent and nano-silica and reacting at a temperature of 60-90°C for 6-12 hours.

[0031] In a preferred embodiment, the weight ratio of the nano-silica to the silane coupling agent is 1:3-5.

[0032] In the method described in this invention, in step (1), the reaction is carried out under alkaline conditions. There are no special requirements for the pH value, as long as the conditions are alkaline. In a preferred embodiment, the pH is 8.5-9.5.

[0033] In a preferred embodiment, in order to improve the reaction efficiency of hydroquinone and thus improve the gel strength and long-term high-temperature and high-salt resistance of the nano-silicon-supported para-phenolic prepolymer crosslinking agent, in step (1), the molar ratio of hydroquinone to ethylenediamine is 1:0.03-0.07; specifically, it can be 1:0.03, 1:0.035, 1:0.04, 1:0.045, 1:0.05, 1:0.055, 1:0.06, 1:0.065 or 1:0.07.

[0034] In a preferred embodiment, in order to further improve the high temperature and high salt resistance of the nano-silicon-supported para-phenolic prepolymer crosslinking agent, in step (1), the weight ratio of the hydroquinone to the silane coupling agent-modified nano-silica is 20:0.1-0.2.

[0035] In a preferred embodiment, in order to improve the dispersion performance of the silane coupling agent modified nano-silica, and thereby improve the strength and high temperature and high salt resistance of the nano-silica loaded with para-phenolic prepolymer crosslinking agent after gelation, in step (1), the weight ratio of hydroquinone to the dispersion stabilizer is 20:0.1-0.2.

[0036] In a preferred embodiment, the reaction conditions in step (1) include: a temperature of 120-160°C and a time of 14-20h.

[0037] In a preferred embodiment, the molar ratio of the amount of hydroquinone to the total amount of hexamethylenetetramine used in steps (2) and (3) is 1:0.5-1.5; based on this, a nano-silicon-supported para-phenolic prepolymer crosslinking agent with good gel strength and good flowability is formed.

[0038] In a preferred embodiment, the reaction conditions in step (2) include a temperature of 70-85°C and a time of 3-4 hours.

[0039] In a preferred embodiment, the reaction conditions in step (3) include: a temperature of 80-90°C and a time of 4-6 hours.

[0040] In the method described in this invention, steps (1)-(3) are all carried out in the presence of a solvent. There are no special requirements for the solvent, as long as it can dissolve and disperse the corresponding substances in steps (1)-(3) to produce the corresponding reactions; for example, the solvent can be water.

[0041] A second aspect of the present invention provides a nano-silicon-supported para-phenolic prepolymer crosslinking agent prepared by the above method.

[0042] The nano-silicon-supported para-phenolic prepolymer crosslinking agent prepared by the above method uses nano-silica modified with silane coupling agent as a rigid filler to construct a denser spatial network, exhibiting stronger gelling and viscoelastic properties while also possessing good high-temperature and high-salt resistance. Furthermore, by reacting with hexamethylenetetramine in steps and controlling the temperature difference between the two steps, the final nano-silicon-supported para-phenolic prepolymer crosslinking agent possesses good flow properties and gelling strength. When used in oilfield development, it exhibits good permeability, thereby improving the plugging rate and oilfield recovery rate.

[0043] A third aspect of the present invention provides a nano-silicon-supported para-phenolic gel, wherein the nano-silicon-supported para-phenolic gel contains a functional polymer and the above-mentioned nano-silicon-supported para-phenolic prepolymer crosslinking agent.

[0044] Based on the combination of numerous cross-linking functional groups on the surface of the nano-silicon material in the nano-silicon-supported para-phenolic prepolymer cross-linking agent with the functional polymer network, the network skeleton strength of the phenolic gel is enhanced. Through the synergistic effects of physical space filling and covalent bonding between the nano-silicon-supported para-phenolic prepolymer cross-linking agent and the polymer network, the dispersion performance of the nano-silicon material in the network skeleton is enhanced, forming a "nano-barrier" in the nano-silicon-supported para-phenolic gel. This hinders the migration of water molecules and salt ions in the gel network, improves the water-binding capacity of the nano-silicon-supported para-phenolic gel, slows down the degradation rate of the cross-linked network, and plays a long-term role in improving the heterogeneity of high-temperature and high-salinity oil reservoirs, thereby increasing the crude oil recovery rate.

[0045] In a preferred embodiment, in order to further improve the high temperature and high salt resistance and strength of the nano-silicon-supported para-phenolic gel, the weight ratio of the functional polymer to the nano-silicon-supported para-phenolic prepolymer crosslinking agent is 1:3-8.

[0046] In a preferred embodiment, the functional polymer is a copolymer of acrylamide monomers and sulfonic acid monomers.

[0047] In a specific embodiment, the acrylamide monomer is acrylamide and / or partially hydrolyzed polyacrylamide; the sulfonic acid monomer is 2-acrylamido-2-methylpropanesulfonic acid and / or sodium p-styrenesulfonate.

[0048] In a preferred embodiment, in order to further improve the high temperature and high salt resistance and strength of the nano-silicon-supported para-phenolic gel, the weight-average molecular weight of the functional polymer is 10 million to 20 million.

[0049] In one specific embodiment, the nano-silicon-supported para-phenolic gel is prepared by the following process: mixing the functional polymer with water, then adding the nano-silicon-supported para-phenolic prepolymer crosslinking agent, and then aging.

[0050] In a preferred embodiment, the weight ratio of the functional polymer to the water is 0.5-0.8:100, preferably 0.4-0.7:100.

[0051] In a preferred embodiment, the weight ratio of the nano-silicon-supported para-phenolic prepolymer crosslinking agent to the water is 2.4-4:100, preferably 3-4:100.

[0052] In a preferred embodiment, the aging conditions include a temperature of 140-160°C and a time of 36-48 hours; more preferably, the temperature is 145-155°C and the time is 36-48 hours.

[0053] The fourth aspect of this invention provides the application of the above-mentioned nano-silicon-supported para-phenolic gel in the crude oil extraction process of high-temperature and high-salinity oil reservoirs.

[0054] In a preferred embodiment, the application process includes: first injecting the functional polymer into the formation, then injecting the nano-silicon-supported para-phenolic prepolymer crosslinking agent, followed by aging; based on this, the nano-silicon-supported para-phenolic gel is formed in the oilfield formation. The nano-silicon-supported para-phenolic gel exhibits high gel strength and strong aging stability under ultra-high temperature and high salt conditions. Furthermore, based on the rigid physical filling, interface enhancement, and ion buffering mechanisms of silane coupling agent-modified nano-silica, as well as the synergistic construction of a dense and stable network structure with the polymer, the performance of the nano-silicon-supported para-phenolic gel under ultra-high temperature and high salt conditions (160℃, 25℃) is significantly improved. 10 4 The structure, rheological properties, and reservoir large-pore plugging performance of the nano-silicon loaded para-phenolic gel in oilfields significantly improve the recovery rate during the exploitation of high-temperature and high-salinity oilfields. In practical applications, the core pore permeability after plugging with nano-silicon loaded para-phenolic gel is less than 75mD, less than 20mD in preferred cases, and can reach as low as 12mD. The plugging rate is as high as 85% or more, up to 96% in preferred cases, and up to 97.6%.

[0055] In a preferred embodiment, the salinity of formation water and / or reservoir formation water in the formation may be 10. 10 4 -30 10 4 mg / L, preferably 15 mg / L 10 4 -25 10 4 mg / L.

[0056] The following examples further illustrate the present invention's nano-silicon-supported para-phenolic prepolymer crosslinking agent, its preparation method, and its application. These examples are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures; however, the scope of protection of the present invention is not limited to the following examples.

[0057] Unless otherwise specified, the experimental methods used in the following examples are conventional methods in the art. Unless otherwise specified, the experimental materials used in the following examples are commercially available; the silane coupling agent-modified nano-silica used in the following examples and comparative examples was prepared by the following method: Silane coupling agent modified nano-silica S1: KH560 is mixed with nano-silica and then reacted at 80°C for 10 h. The weight ratio of the nano-silica to the KH560 is 1:4, and the average particle size of the silane coupling agent modified nano-silica S1 is 20 nm. Silane coupling agent modified nano-silica S2: KH550 is mixed with nano-silica and then reacted at 80°C for 10 h. The weight ratio of nano-silica to KH550 is 1:4, and the average particle size of silane coupling agent modified nano-silica S2 is 20 nm.

[0058] Example 1 (1) Hydroquinone and water are mixed to form a hydroquinone solution with a mass concentration of 20 wt%, and then mixed with ethylenediamine, wherein the molar ratio of the hydroquinone to the ethylenediamine is 1:0.05, the pH is adjusted to 8.5, and then silane coupling agent modified nano-silica S1 and dispersant stabilizer (sodium silicate solution with a mass concentration of 20 wt%) are added and reacted at 160°C for 5 h, and then the temperature is lowered to 120°C and reacted for 14 h to obtain the first reaction solution, wherein the weight ratio of the silane coupling agent modified nano-silica S1 to hydroquinone is 0.1:20, and the weight ratio of the dispersant stabilizer to hydroquinone is 0.1:20; (2) Mix hexamethylenetetramine and water to obtain a hexamethylenetetramine solution with a mass concentration of 40 wt%. React the first reaction solution and a portion of the hexamethylenetetramine solution at 75 °C for 3 h to obtain a second reaction solution. (3) React the second reaction solution and the remaining hexamethylenetetramine solution at 85°C for 5 hours; The molar ratio of the amount of hydroquinone to the total amount of hexamethylenetetramine used in steps (2) and (3) is 1:0.5. Based on the total weight of hexamethylenetetramine used in steps (2) and (3), the amount of hexamethylenetetramine used in step (2) is 50% by weight, and the amount of hexamethylenetetramine used in step (3) is 50% by weight.

[0059] Example 2 (1) Hydroquinone and water are mixed to form a hydroquinone solution with a mass concentration of 20 wt%, and then mixed with ethylenediamine, wherein the molar ratio of the hydroquinone to the ethylenediamine is 1:0.05, the pH is adjusted to 9, and then silane coupling agent modified nano-silica S1 and dispersant stabilizer (sodium silicate solution with a mass concentration of 20 wt%) are added and reacted at 160°C for 5 h, and then the temperature is lowered to 120°C and reacted for 14 h to obtain the first reaction solution, wherein the weight ratio of the silane coupling agent modified nano-silica S1 to hydroquinone is 0.1:20, and the weight ratio of the dispersant stabilizer to hydroquinone is 0.1:20; (2) Mix hexamethylenetetramine and water to obtain a hexamethylenetetramine solution with a mass concentration of 40 wt%. React the first reaction solution and a portion of the hexamethylenetetramine solution at 75 °C for 3 h to obtain a second reaction solution. (3) React the second reaction solution and the remaining hexamethylenetetramine solution at 85°C for 5 hours; The molar ratio of the amount of hydroquinone to the total amount of hexamethylenetetramine used in steps (2) and (3) is 1:1.5. Based on the total weight of hexamethylenetetramine used in steps (2) and (3), the amount of hexamethylenetetramine used in step (2) is 50% by weight and the amount of hexamethylenetetramine used in step (3) is 50% by weight.

[0060] Example 3 (1) Hydroquinone and water are mixed to form a hydroquinone solution with a mass concentration of 20 wt%, and then mixed with ethylenediamine, wherein the molar ratio of the hydroquinone to the ethylenediamine is 1:0.05, the pH is adjusted to 9, and then silane coupling agent modified nano-silica S1 and dispersant stabilizer (sodium silicate solution with a mass concentration of 20 wt%) are added and reacted at 160°C for 5 h, and then the temperature is lowered to 120°C and reacted for 12 h to obtain the first reaction solution, wherein the weight ratio of the silane coupling agent modified nano-silica S1 to hydroquinone is 0.15:20, and the weight ratio of the dispersant stabilizer to hydroquinone is 0.1:20; (2) Mix hexamethylenetetramine and water to obtain a hexamethylenetetramine solution with a mass concentration of 40 wt%. React the first reaction solution and a portion of the hexamethylenetetramine solution at 75 °C for 3 h to obtain a second reaction solution. (3) React the second reaction solution and the remaining hexamethylenetetramine solution at 85°C for 5 hours; The molar ratio of the amount of hydroquinone to the total amount of hexamethylenetetramine used in steps (2) and (3) is 1:1. Based on the total weight of hexamethylenetetramine used in steps (2) and (3), the amount of hexamethylenetetramine used in step (2) is 70% by weight and the amount of hexamethylenetetramine used in step (3) is 30% by weight.

[0061] Example 4 The implementation was carried out in accordance with Example 1, except that the weight ratio of the silane coupling agent modified nano-silica S1 to hydroquinone was 0.05:20, that is: (1) Hydroquinone and water are mixed to form a hydroquinone solution with a mass concentration of 20 wt%, and then mixed with ethylenediamine, wherein the molar ratio of the hydroquinone to the ethylenediamine is 1:0.05, the pH is adjusted to 8.5, and then silane coupling agent modified nano-silica S1 and dispersant stabilizer (sodium silicate solution with a mass concentration of 20 wt%) are added and reacted at 160°C for 5 h, and then the temperature is lowered to 120°C and reacted for 14 h to obtain the first reaction solution, wherein the weight ratio of the silane coupling agent modified nano-silica S1 to hydroquinone is 0.05:20, and the weight ratio of the dispersant stabilizer to hydroquinone is 0.1:20; (2) Mix hexamethylenetetramine and water to obtain a hexamethylenetetramine solution with a mass concentration of 40 wt%. React the first reaction solution and a portion of the hexamethylenetetramine solution at 75 °C for 3 h to obtain a second reaction solution. (3) React the second reaction solution and the remaining hexamethylenetetramine solution at 85°C for 5 hours; The molar ratio of the amount of hydroquinone to the total amount of hexamethylenetetramine used in steps (2) and (3) is 1:0.5. Based on the total weight of hexamethylenetetramine used in steps (2) and (3), the amount of hexamethylenetetramine used in step (2) is 50% by weight, and the amount of hexamethylenetetramine used in step (3) is 50% by weight.

[0062] Example 5 The implementation was carried out in accordance with Example 1, except that the weight ratio of the silane coupling agent modified nano-silica S1 to hydroquinone was 0.3:20, that is: (1) Hydroquinone and water are mixed to form a hydroquinone solution with a mass concentration of 20 wt%, and then mixed with ethylenediamine, wherein the molar ratio of the hydroquinone to the ethylenediamine is 1:0.05, the pH is adjusted to 8.5, and then silane coupling agent modified nano-silica S1 and dispersant stabilizer (sodium silicate solution with a mass concentration of 20 wt%) are added and reacted at 160°C for 5 h, and then the temperature is lowered to 120°C and reacted for 14 h to obtain the first reaction solution, wherein the weight ratio of the silane coupling agent modified nano-silica S1 to hydroquinone is 0.3:20, and the weight ratio of the dispersant stabilizer to hydroquinone is 0.1:20; (2) Mix hexamethylenetetramine and water to obtain a hexamethylenetetramine solution with a mass concentration of 40 wt%. React the first reaction solution and a portion of the hexamethylenetetramine solution at 75 °C for 3 h to obtain a second reaction solution. (3) React the second reaction solution and the remaining hexamethylenetetramine solution at 85°C for 5 hours; The molar ratio of the amount of hydroquinone to the total amount of hexamethylenetetramine used in steps (2) and (3) is 1:0.5. Based on the total weight of hexamethylenetetramine used in steps (2) and (3), the amount of hexamethylenetetramine used in step (2) is 50% by weight, and the amount of hexamethylenetetramine used in step (3) is 50% by weight.

[0063] Comparative Example 1 The procedure was carried out in accordance with Example 1, except that an equal weight of phenol was used to replace hydroquinone, i.e.: (1) Phenol and water are mixed to form a phenol solution with a mass concentration of 20 wt%, and then mixed with ethylenediamine, wherein the molar ratio of the amount of phenol to the amount of ethylenediamine is 1:0.05, the pH is adjusted to 8.5, and then silane coupling agent modified nano-silica S1 and dispersant stabilizer (sodium silicate solution with a mass concentration of 20 wt%) are added and reacted at 160°C for 5 h, and then the temperature is lowered to 120°C and reacted for 14 h to obtain the first reaction solution, wherein the weight ratio of the amount of silane coupling agent modified nano-silica S1 to phenol is 0.1:20, and the weight ratio of the amount of dispersant stabilizer to phenol is 0.1:20; (2) Mix hexamethylenetetramine and water to obtain a hexamethylenetetramine solution with a mass concentration of 40 wt%. React the first reaction solution and a portion of the hexamethylenetetramine solution at 75 °C for 3 h to obtain a second reaction solution. (3) React the second reaction solution and the remaining hexamethylenetetramine solution at 85°C for 5 hours; The molar ratio of the amount of phenol to the total amount of hexamethylenetetramine used in steps (2) and (3) is 1:0.5. Based on the total weight of hexamethylenetetramine used in steps (2) and (3), the amount of hexamethylenetetramine used in step (2) is 50% by weight and the amount of hexamethylenetetramine used in step (3) is 50% by weight.

[0064] Comparative Example 2 The implementation was carried out in accordance with Example 1, except that an equal weight of nano-silica was used to replace the silane coupling agent-modified nano-silica S1, that is: (1) Hydroquinone and water are mixed to form a hydroquinone solution with a mass concentration of 20 wt%, and then mixed with ethylenediamine, wherein the molar ratio of the hydroquinone to the ethylenediamine is 1:0.05, the pH is adjusted to 8.5, and then nano-silica and a dispersant (sodium silicate solution with a mass concentration of 20 wt%) are added and reacted at 160°C for 5 h, and then the temperature is lowered to 120°C and reacted for 14 h to obtain the first reaction solution, wherein the weight ratio of the nano-silica to the hydroquinone is 0.1:20, and the weight ratio of the dispersant to the hydroquinone is 0.1:20; (2) Mix hexamethylenetetramine and water to obtain a hexamethylenetetramine solution with a mass concentration of 40 wt%. React the first reaction solution and a portion of the hexamethylenetetramine solution at 75 °C for 3 h to obtain a second reaction solution. (3) React the second reaction solution and the remaining hexamethylenetetramine solution at 85°C for 5 hours; The molar ratio of the amount of hydroquinone to the total amount of hexamethylenetetramine used in steps (2) and (3) is 1:0.5. Based on the total weight of hexamethylenetetramine used in steps (2) and (3), the amount of hexamethylenetetramine used in step (2) is 50% by weight, and the amount of hexamethylenetetramine used in step (3) is 50% by weight.

[0065] Comparative Example 3 The procedure was carried out as described in Example 1, except that no dispersant stabilizer was added, i.e.: (1) Hydroquinone and water are mixed to form a hydroquinone solution with a mass concentration of 20 wt%, and then mixed with ethylenediamine, wherein the molar ratio of the amount of hydroquinone to the amount of ethylenediamine is 1:0.05, the pH is adjusted to 8.5, and then silane coupling agent modified nano-silica S1 is added and reacted at 160°C for 5 h, and then the temperature is lowered to 120°C and reacted for 14 h to obtain the first reaction solution, wherein the weight ratio of the amount of the amount of silane coupling agent modified nano-silica S1 to the amount of hydroquinone is 0.1:20; (2) Mix hexamethylenetetramine and water to obtain a hexamethylenetetramine solution with a mass concentration of 40 wt%. React the first reaction solution and a portion of the hexamethylenetetramine solution at 75 °C for 3 h to obtain a second reaction solution. (3) React the second reaction solution and the remaining hexamethylenetetramine solution at 85°C for 5 hours; The molar ratio of the amount of hydroquinone to the total amount of hexamethylenetetramine used in steps (2) and (3) is 1:0.5. Based on the total weight of hexamethylenetetramine used in steps (2) and (3), the amount of hexamethylenetetramine used in step (2) is 50% by weight, and the amount of hexamethylenetetramine used in step (3) is 50% by weight.

[0066] Comparative Example 4 The procedure was carried out as described in Example 1, except that the hexamethylenetetramine solution was added in one step, i.e.: (1) Hydroquinone and water are mixed to form a hydroquinone solution with a mass concentration of 20 wt%, and then mixed with ethylenediamine, wherein the molar ratio of the hydroquinone to the ethylenediamine is 1:0.05, the pH is adjusted to 8.5, and then silane coupling agent modified nano-silica S1 and dispersant stabilizer (sodium silicate solution with a mass concentration of 20 wt%) are added and reacted at 160°C for 5 h, and then the temperature is lowered to 120°C and reacted for 14 h to obtain the first reaction solution, wherein the weight ratio of the silane coupling agent modified nano-silica S1 to hydroquinone is 0.1:20, and the weight ratio of the dispersant stabilizer to hydroquinone is 0.1:20; (2) Hexamethylenetetramine and water were mixed to obtain a hexamethylenetetramine solution with a mass concentration of 40 wt%, and the first reaction solution and the hexamethylenetetramine solution were reacted at 85 °C for 8 h; The molar ratio of hydroquinone to hexamethylenetetramine is 1:0.5.

[0067] Comparative Example 5 The procedure was carried out as described in Example 1, except that an equal weight of catechol was used to replace hydroquinone, i.e.: (1) A catechol solution with a mass concentration of 20 wt% is formed by mixing catechol and water, and then mixed with ethylenediamine, wherein the molar ratio of the catechol to the ethylenediamine is 1:0.05. The pH is adjusted to 8.5, and then silane coupling agent modified nano-silica S1 and dispersant stabilizer (sodium silicate solution with a mass concentration of 20 wt%) are added. The mixture is reacted at 160°C for 5 h, and then the temperature is lowered to 120°C and reacted for 14 h to obtain the first reaction solution, wherein the weight ratio of the silane coupling agent modified nano-silica S1 to the catechol is 0.1:20, and the weight ratio of the dispersant stabilizer to the catechol is 0.1:20. (2) Mix hexamethylenetetramine and water to obtain a hexamethylenetetramine solution with a mass concentration of 40 wt%. React the first reaction solution and a portion of the hexamethylenetetramine solution at 75 °C for 3 h to obtain a second reaction solution. (3) React the second reaction solution and the remaining hexamethylenetetramine solution at 85°C for 5 hours; The molar ratio of the amount of catechol to the total amount of hexamethylenetetramine used in steps (2) and (3) is 1:0.5. Based on the total weight of hexamethylenetetramine used in steps (2) and (3), the amount of hexamethylenetetramine used in step (2) is 50% by weight and the amount of hexamethylenetetramine used in step (3) is 50% by weight.

[0068] Comparative Example 6 The procedure was carried out in accordance with Example 1, except that the reaction temperature in step (2) was 10°C higher than the reaction temperature in step (3), that is: (1) Hydroquinone and water are mixed to form a hydroquinone solution with a mass concentration of 20 wt%, and then mixed with ethylenediamine, wherein the molar ratio of the hydroquinone to the ethylenediamine is 1:0.05, the pH is adjusted to 8.5, and then silane coupling agent modified nano-silica S1 and dispersant stabilizer (sodium silicate solution with a mass concentration of 20 wt%) are added and reacted at 160°C for 5 h, and then the temperature is lowered to 120°C and reacted for 14 h to obtain the first reaction solution, wherein the weight ratio of the silane coupling agent modified nano-silica S1 to hydroquinone is 0.1:20, and the weight ratio of the dispersant stabilizer to hydroquinone is 0.1:20; (2) Mix hexamethylenetetramine and water to obtain a hexamethylenetetramine solution with a mass concentration of 40 wt%. React the first reaction solution and a portion of the hexamethylenetetramine solution at 95 °C for 3 h to obtain a second reaction solution. (3) React the second reaction solution and the remaining hexamethylenetetramine solution at 85°C for 5 hours; The molar ratio of the amount of hydroquinone to the total amount of hexamethylenetetramine used in steps (2) and (3) is 1:0.5. Based on the total weight of hexamethylenetetramine used in steps (2) and (3), the amount of hexamethylenetetramine used in step (2) is 50% by weight, and the amount of hexamethylenetetramine used in step (3) is 50% by weight.

[0069] Comparative Example 7 The implementation was carried out in accordance with Example 1, except that an equal weight of silane coupling agent modified nano-silica S2 was used to replace silane coupling agent modified nano-silica S1, that is: (1) Hydroquinone and water are mixed to form a hydroquinone solution with a mass concentration of 20 wt%, and then mixed with ethylenediamine, wherein the molar ratio of the hydroquinone to the ethylenediamine is 1:0.05, the pH is adjusted to 8.5, and then silane coupling agent modified nano-silica S2 and dispersant stabilizer (sodium silicate solution with a mass concentration of 20 wt%) are added and reacted at 160°C for 5 h, and then the temperature is lowered to 120°C and reacted for 14 h to obtain the first reaction solution, wherein the weight ratio of the silane coupling agent modified nano-silica S2 to hydroquinone is 0.1:20 and the weight ratio of the dispersant stabilizer to hydroquinone is 0.1:20; (2) Mix hexamethylenetetramine and water to obtain a hexamethylenetetramine solution with a mass concentration of 40 wt%. React the first reaction solution and a portion of the hexamethylenetetramine solution at 75 °C for 3 h to obtain a second reaction solution. (3) React the second reaction solution and the remaining hexamethylenetetramine solution at 85°C for 5 hours; The molar ratio of the amount of hydroquinone to the total amount of hexamethylenetetramine used in steps (2) and (3) is 1:0.5. Based on the total weight of hexamethylenetetramine used in steps (2) and (3), the amount of hexamethylenetetramine used in step (2) is 50% by weight, and the amount of hexamethylenetetramine used in step (3) is 50% by weight.

[0070] Test case (1) The nano-silicon-supported para-phenolic crosslinking agent prepared in Example 1 was subjected to infrared spectroscopy testing, and the results are as follows: Figure 1 As shown; Depend on Figure 1 It can be seen that: 1232cm in the infrared spectrum -1 The characteristic peak of the benzene ring COC appeared at 1023 cm⁻¹. -1The COC characteristic peak of silane coupling agent KH560 appeared at the above location. The appearance of the above characteristic peak proves that under the catalysis of ethylenediamine, silane coupling agent KH560 successfully opened the ring and reacted with the benzene ring hydroxyl group in the para-phenolic prepolymer, proving the successful synthesis of nano-silicon-supported para-phenolic prepolymer crosslinking agent. (2) The performance of the samples prepared in the examples and comparative examples was tested as follows: The simulated formation water (with a salinity of 25 × 10⁻⁶) was prepared. 4 The functional polymer (a copolymer of acrylamide and 2-acrylamido-2-methylpropanesulfonic acid, with a weight average molecular weight of 10 million) was added to the solution and stirred until the functional polymer swelled. Then, the solution was injected into the samples prepared in the examples and comparative examples and stirred until completely dissolved to obtain a gel. The solution was then placed in an oven at 160°C for 36 hours to obtain nano-silicon-supported para-phenolic gel. The weight ratio of the functional polymer to the sample was 1:5, and the weight ratio of the functional polymer to simulated formation water was 0.6:100. High-temperature and high-salt gelation effect test: The GSC strength code method was used to observe the flow state of the sample at 160℃ for 12h, 1d, 2d, 3d, 10d, 30d, 60d, and 90d. When the sample bottle is inverted, most of the gel flows to the cap, indicating a strength level of AC. When the sample bottle is vertically inverted, only a small portion (15%-10%) of the gel does not easily flow to the cap (usually described as a gel with a long tongue), indicating a strength level of D. When the sample bottle is vertically inverted, the gel flows very slowly to the cap, indicating a strength level of E. A highly deformed sample that is not flowing indicates a strength level of F. A moderately deformed sample that is not flowing indicates a strength level of G. A slightly deformed sample that is not flowing indicates a strength level of H. The dehydration rate of the sample was the ratio of the difference between the weight of the gelling liquid before gelation and the weight of the gel after gelation to the weight of the gelling liquid before gelation. The test results are shown in Table 1. Simultaneously, the dehydration rate of the prepared gel under high temperature and high salt conditions was tested, and the test results are shown in Table 2. The morphology of the nano-silicon-supported para-phenolic gel prepared in Example 1 after aging for 90 days is shown in Table 2. Figure 2 As shown; Depend on Figure 2 It can be seen that the nano-silicon-supported para-phenolic gel prepared in Example 1 has good gel strength. After aging for 90 days, the nano-silicon-supported para-phenolic gel sample is slightly deformed and does not flow. (2) Sealing performance test: The core sample was a medium-to-high permeability sandstone core, with a core length of 10cm, a diameter of 2.5cm, and a core porosity of 28.4%. The core displacement device was used for testing. The core displacement device included a plunger pump, a high-temperature and high-pressure intermediate container, a core holder, a high-temperature and high-pressure oven, and a back pressure valve. The specific operation steps were as follows: The core sample was dried at 60℃ for 48h. The initial oil saturation was established by vacuum pressurizing saturated crude oil. A water drive test was carried out. The core was displaced using simulated formation water. The injection pressure was recorded during the test, and the confining pressure was tracked to be 1MPa. The back pressure was 4 MPa, the temperature was 160℃, and the injection rate was 0.2 mL / min. Nano-silica-supported para-phenolic gel was injected, with a gelling solution filling one pore volume. The confining pressure was 1 MPa, the back pressure was 4 MPa, the temperature was 160℃, and the injection rate was 0.2 mL / min. It was aged in a high-temperature, high-pressure oven until complete gelation. A secondary waterflooding test was conducted using simulated formation water. The injection pressure was recorded during the test, with the confining pressure at 1 MPa, the back pressure at 4 MPa, the temperature at 160℃, and the injection rate at 0.2 mL / min. The test results are shown in Table 3. Figure 3 This is an injection pressure curve before and after the sample of Example 1 was prepared and sealed with nano-silicon-loaded para-phenolic gel to seal the core. Depend on Figure 3 It can be seen that the pressure difference before and after the first water injection of the core before sealing was 2.5 kPa. After the phenolic gel prepared in Example 1 was injected and aged, the second water injection was carried out, and the pressure difference was 104.2 kPa. The sealing rate of the gel reached 97.6%. The permeability of the core after sealing decreased from the original 500 mD to 12 mD, showing a good sealing effect.

[0071] Table 1

[0072] Table 2

[0073] Table 3

[0074] As can be seen from the data in Tables 1-3, the nano-silicon-supported para-phenolic prepolymer crosslinking agent prepared by the method described in this invention has good gel strength and flow properties. When applied to oilfield development, it is combined with functional polymers to prepare nano-silicon-supported para-phenolic gel. This nano-silicon-supported para-phenolic gel has good gel strength and ultra-high temperature and high salt tolerance, and has a good plugging rate for oilfields, greatly improving oilfield recovery rate.

[0075] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for supporting a nano-silicon-based para-phenolic prepolymer crosslinking agent, characterized in that, The method includes the following steps: (1) Under alkaline conditions, hydroquinone, ethylenediamine, silane coupling agent modified nano-silica and dispersant stabilizer are reacted to obtain the first reaction solution; (2) The first reaction solution and a portion of hexamethylenetetramine are reacted to obtain the second reaction solution; (3) React the second reaction solution with the remaining hexamethylenetetramine; Based on the total weight of hexamethylenetetramine used in steps (2) and (3), the amount of hexamethylenetetramine used in step (2) is 50-70% by weight, and the amount of hexamethylenetetramine used in step (3) is 30-50% by weight. The reaction temperature in step (3) is 5-20°C higher than the reaction temperature in step (2); In step (1), the silane coupling agent is KH560.

2. The method according to claim 1, characterized in that, In step (1), the dispersant stabilizer is selected from one or more of silicates, sodium hexametaphosphate, and sodium dodecylbenzenesulfonate; and / or The particle size of the silane coupling agent modified nano-silica is 10-100 nm.

3. The method according to claim 1 or 2, characterized in that, In step (1), the molar ratio of hydroquinone to ethylenediamine is 1:0.03-0.07; and / or The weight ratio of hydroquinone to the silane coupling agent-modified nano-silica is 20:0.1-0.2; and / or The weight ratio of hydroquinone to the dispersant stabilizer is 20:0.1-0.

2.

4. The method according to any one of claims 1-3, characterized in that, In step (1), the reaction conditions include: a temperature of 120-160℃ and a time of 14-20h.

5. The method according to any one of claims 1-4, characterized in that, The molar ratio of the amount of hydroquinone used to the total amount of hexamethylenetetramine used in steps (2) and (3) is 1:0.5-1.

5.

6. The method according to any one of claims 1-5, characterized in that, In step (2), the reaction conditions include: a temperature of 70-85℃ and a time of 3-4 hours; and / or In step (3), the reaction conditions include a temperature of 80-90℃ and a time of 4-6h.

7. A nano-silicon-supported para-phenolic prepolymer crosslinking agent prepared by the method according to any one of claims 1-6.

8. A nano-silicon-supported para-phenolic gel, characterized in that, The nano-silicon-supported para-phenolic gel contains a functional polymer and the nano-silicon-supported para-phenolic prepolymer crosslinking agent as described in claim 7. Preferably, the weight ratio of the functional polymer to the nano-silicon-supported para-phenolic prepolymer crosslinking agent is 1:3-8.

9. The nano-silicon-supported para-phenolic gel according to claim 8, characterized in that, The functional polymer is a copolymer of acrylamide monomers and sulfonic acid monomers; Preferably, the weight-average molecular weight of the functional polymer is 10 million to 20 million.

10. The application of the nano-silicon-supported para-phenolic gel according to claim 8 or 9 in the crude oil extraction process of high-temperature and high-salinity oil reservoirs; Preferably, the application process includes: The functional polymer is first injected into the formation, followed by the nano-silicon-supported para-phenolic prepolymer crosslinking agent, and then aged.

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