Ultrahigh-temperature high-salinity water-based guanidium gel fracturing fluid and preparation method thereof

Abstract

The application discloses a kind of superhigh temperature high salinity water-based guan gum fracturing fluid and preparation method.The guan gum fracturing fluid includes mass ratio 100: (0.1-0.6): (0.2-0.8): (0.01-0.08) of base fluid, buffering agent, cage molecule complex crosslinking agent and gel breaker;The base fluid includes the following weight percentage components: cyclodextrin modified thickening agent 0.55-0.6%, composite antioxidant 0.1-0.6%, multiple effect adjuvant 0.4-0.8%, bactericide 0.1-0.2%, and the balance is high salinity water.The superhigh temperature high salinity water-based guan gum fracturing fluid of the application can withstand 200℃ through chemical modification of guan gum thickening agent and synergistic effect of various additives, can be directly prepared using high salinity water, achieve good fracture creation, sand carrying, temperature and shear resistance, low filtration loss and low damage, meet the needs of offshore and onshore oilfield superdeep superhigh temperature low permeability reservoir fracturing operation.

Description

Technical Field

[0001] This invention relates to the field of fracturing and production enhancement technology for low-permeability oil and gas resources, and particularly to an ultra-high temperature, high-salinity water-based guar gum fracturing fluid and its preparation method. Background Technology

[0002] China National Offshore Oil Corporation (CNOOC) has a large number of low-permeability reservoirs in its offshore oilfields, including 541 million tons of proven crude oil reserves and 543.5 billion cubic meters of proven natural gas reserves. Fracturing is a crucial technology for developing low-permeability offshore oil and gas reservoirs. However, current offshore fracturing is limited by factors such as operating space on offshore platforms, load-bearing capacity, operational safety, and transportation conditions, leading to a series of problems including high construction difficulty, long cycles, high costs, and limited scale. Using seawater directly to prepare fracturing fluid on offshore platforms can solve the problem of limited freshwater resources and save on the cost of investing in seawater desalination plants and the operating space they occupy on the platform. Therefore, high-salinity water-based fracturing fluids can effectively improve the difficulties of offshore fracturing operations and facilitate the large-scale development of low-permeability offshore oil and gas resources.

[0003] Given that the average displacement of offshore fracturing operations at this stage is 3.5 m³ / s... 3 The fracturing fluid is designed for low-displacement operations and uses high-density, large-particle-size ceramic particles as proppant. Combined with the generally high temperatures (currently reaching over 200℃) in deep, low-permeability offshore reservoirs and the use of high-salinity water for fluid preparation, high-salinity water-based guar gum fracturing fluids suitable for low-displacement operations and with more stable key properties such as high temperature resistance, salt resistance, shear resistance, and static proppant carrying capacity remain the focus of research and development for offshore oilfield fracturing fluid products.

[0004] Regarding high-salinity water-based fracturing fluids, Chinese invention patent CN 103131405A discloses a high-temperature seawater-based fracturing fluid suitable for formation temperatures of 160℃ and its preparation method. This high-temperature seawater-based fracturing fluid is prepared by reacting a base fluid with a crosslinking agent. The base fluid contains 96–98 parts seawater, 0.5–1.0 parts thickener, 0.8–1.5 parts chelating regulator, 0.3–1.0 parts temperature stabilizer, 0.1–0.5 parts surfactant, and 0.01–0.05 parts breaker. The thickener is a guanidine gum derivative modified with hydroxyalkyl, carboxylalkyl, and sulfonic acid groups; the chelating regulator is ethylenediaminetetraacetic acid (EDTA), etc.; the temperature stabilizer is hydrazine hydrate, etc.; the surfactant is a polyether carboxylate type surfactant, etc.; and the breaker is potassium perchlorate, etc. The crosslinking agent comprises 0.5-1.5 parts, including 10-25 parts of the main agent, 10-20 parts of the complexing agent, 10-30 parts of the co-complexing agent, and 25-70 parts of the organic solvent. The main agent is a zirconium or titanium-containing metal compound, the complexing agent is an organic acid or ethanolamine, the co-complexing agent is ethylene glycol or glycerol, and the organic solvent is ethanol or acetone. This high-temperature seawater-based fracturing fluid is resistant to temperatures up to 160℃. Chinese invention patent CN 103215024A discloses a seawater-based fracturing fluid for fracturing high-temperature marine oil and gas reservoirs. This seawater-based fracturing fluid comprises a base fluid and a crosslinking agent. The base fluid contains 0.3–0.8% thickener, 0.1–0.3% buffer, 0.1–0.5% flow aid, 0.2–0.6% temperature-resistant enhancer, 0.8–1.5% oxygen scavenger, 0.1–0.3% bactericide, 0.1–0.5% clay stabilizer, 0.1–0.5% foaming agent, and 0.04–0.06% breaker, with the balance being seawater-based. The thickener is hydroxypropyl guar gum, etc.; the pH adjuster is potassium carbonate, etc.; the flow aid is quaternary ammonium salt surfactant, etc.; the temperature-resistant enhancer is hydrazine, etc.; the oxygen scavenger is thiourea, etc.; and the breaker is ammonium persulfate, etc. The crosslinking agent accounts for 0.4-0.6%, and is an organozirconium crosslinking agent, etc. This high-temperature seawater-based fracturing fluid is resistant to 150℃. Chinese invention patent with publication number CN 116063585A discloses a modified heat-resistant guar gum and its preparation method. First, long-chain dimethylhydroxyethyl ammonium chloride is prepared through a quaternization reaction. Then, the long-chain dimethylhydroxyethyl ammonium chloride is esterified to prepare a surface-active etherifying agent. Finally, the surface-active etherifying agent is etherified with an alkaline guar gum dispersion to obtain modified heat-resistant guar gum. After crosslinking with the crosslinking agent, the modified heat-resistant guar gum can withstand a temperature of 160℃ under seawater preparation conditions. Chinese invention patent with publication number CN 104498018A discloses a low-concentration guar gum seawater-based fracturing fluid and its preparation method. This seawater-based fracturing fluid includes a base fluid, a pH adjuster, a crosslinking agent, and a breaker, wherein the crosslinking agent is an organoboron crosslinking agent that can be crosslinked multiple times.

[0005] In summary, current research directions for improving the performance of high-salinity water-based guar gum fracturing fluids mainly include: modifying guar gum, developing matching crosslinking agents, and utilizing the chemical and synergistic effects between guar gum and other agents such as crosslinking agents. However, using conventional research approaches and chemical formulations, the synergistic effects between the various components of the fracturing fluid are not strong, thus affecting the key properties of high-salinity water-based guar gum fracturing fluids, such as temperature resistance and shear resistance, under more demanding operating conditions. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides an ultra-high temperature, high-salinity water-based guar gum fracturing fluid and its preparation method. This invention introduces cyclodextrin and adamantane structures into the guar gum thickener and its matching crosslinking agent, respectively. This adds a novel supramolecular interaction—host-guest inclusion—to the conventional chemical crosslinking between the thickener and crosslinking agent. Furthermore, the synergistic effect of buffers and composite antioxidants significantly improves the performance of the high-salinity water-based guar gum fracturing fluid. This ultra-high temperature, high-salinity water-based guar gum fracturing fluid can withstand temperatures up to 200℃, can be directly prepared using high-salinity water, and achieves excellent fracture creation, proppant carrying, temperature and shear resistance, low filtration loss, and low damage, meeting the fracturing requirements of ultra-deep, ultra-high temperature, and low-permeability reservoirs in both offshore and onshore oilfields.

[0007] In a first aspect, the present invention provides an ultra-high temperature, high-mineralization water-based guar gum fracturing fluid, which is achieved by the following technical solution.

[0008] A high-temperature, high-mineralization water-based guar gum fracturing fluid comprises a base fluid, a buffer, a cage-like molecular composite crosslinking agent, and a breaker in a mass ratio of 100:(0.1-0.6):(0.2-0.8):(0.01-0.08); the base fluid comprises the following components in weight percentage: 0.55-0.6% cyclodextrin-modified thickener, 0.1-0.6% composite antioxidant, 0.4-0.8% multi-effect adjuvant, 0.1-0.2% bactericide, and the balance being high-mineralization water with a mineralization of 20000 mg / L to 80000 mg / L.

[0009] Furthermore, the cyclodextrin-modified thickener is prepared by the following steps:

[0010] a. Using ethanol as a solvent, 3-chloropropyltrimethoxysilane was reacted with hydroxypropyl-β-cyclodextrin to generate a modified cyclodextrin with the structure of formula (I); wherein the mass ratio of 3-chloropropyltrimethoxysilane to hydroxypropyl-β-cyclodextrin was 1:(4~6), the reaction temperature was 60~80℃, the reaction time was 4~6h, after the reaction was completed, the mixture was filtered, washed 3 times with acetone, and dried under vacuum to obtain the modified cyclodextrin;

[0011]

[0012]

[0013] R1= or Among them, at least two R1s are ;

[0014] b. Using ethanol as solvent and sodium hydroxide as alkalizing agent, modified cyclodextrin is reacted with hydroxypropyl guar gum to generate a cyclodextrin-modified thickener with the structure of formula (II); wherein the mass ratio of modified cyclodextrin to hydroxypropyl guar gum is (1-10):100, the reaction temperature is 40-60℃, the reaction time is 2-4h, the pH of the system is adjusted to 6-8 with 10%-35% hydrochloric acid, filtered, washed 3 times with ethanol, and vacuum dried to obtain the cyclodextrin-modified thickener;

[0015]

[0016] R= Or H, where, The quantity accounts for ≥90%, and n=500~6000;

[0017]

[0018] R2= or Of these, at least two R2 values ​​are Guar represents the structure of hydroxypropyl guar gum.

[0019] The reaction formula is as follows:

[0020]

[0021]

[0022] R1= or Among them, at least two R1s are ;

[0023]

[0024] R2= or Of these, at least two R2 values ​​are Guar represents the hydroxypropyl guar gum structure.

[0025] Furthermore, the composite antioxidant comprises the following components by weight percentage: 0.1-1% tea polyphenols, 15-20% alkanolamine compounds, 10-15% reducing agent, and the balance being water.

[0026] Furthermore, the amine compound is selected from one or more of monoethanolamine, diethanolamine, and triethanolamine; the reducing agent is selected from one or more of sodium isoascorbate, sodium bisulfite, and sodium thiosulfate.

[0027] Furthermore, the preparation method of the composite antioxidant is as follows: under the conditions of a rotation speed of 100-200 r / min and a temperature of 50-60℃, a specified amount of tea polyphenols, alcohol amine compounds, reducing agents and water are mixed, stirred for 1-2 hours, and filtered to remove solid impurities, thereby obtaining the composite antioxidant.

[0028] Furthermore, the multi-effect adjuvant comprises the following components by weight percentage: 10-15% polyether demulsifier, 0.5-2% fluorocarbon drainage aid, 10-15% clay stabilizer, and the balance being water.

[0029] Furthermore, the polyether demulsifier is selected from any one or more of fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, and fatty amine polyoxyethylene ether; the fluorocarbon emission aid is selected from any one or more of sodium perfluorononenoxybenzenesulfonate, sodium perfluorooctanoate, and sodium perfluorohexanoate; and the clay stabilizer is selected from any one or more of benzyltrimethylammonium chloride, dodecyl dimethylammonium chloride, and dimethyl diallyl ammonium chloride.

[0030] Furthermore, the preparation method of the multi-effect excipient is as follows: under the conditions of a rotation speed of 100-200 r / min and a temperature of 50-60℃, a specified amount of polyether demulsifier, fluorocarbon drainage aid, clay stabilizer and water are mixed, stirred for 1-2 hours, and filtered to remove solid impurities, thereby obtaining the multi-effect excipient.

[0031] Furthermore, the bactericide is selected from any one or more of dodecyl dimethyl benzyl ammonium chloride, isothiazolinone, and polyhexamethylene biguanide.

[0032] Furthermore, the buffer comprises the following components in weight percentage: 5-10% copolymer chelating agent, 5-10% aminocarboxylic acid chelating agent, 4-8% inorganic base, and the balance being water.

[0033] Furthermore, the copolymer-type chelating agent is selected from any one or more of sodium polyacrylate, sodium maleate-acrylic acid copolymer, and sodium polyepoxysuccinate; the aminocarboxylic acid chelating agent is selected from any one or more of disodium ethylenediaminetetraacetate, trisodium nitroglycerin triacetate, and trisodium hydroxyethylethylenediaminetriacetate; and the inorganic base is any one or more of sodium hydroxide, potassium hydroxide, and sodium carbonate.

[0034] Furthermore, the preparation method of the buffer is as follows: under the conditions of a rotation speed of 100-200 r / min and a temperature of 50-60℃, a specified amount of copolymer chelating agent, aminocarboxylic acid chelating agent, inorganic alkali and water are mixed, stirred for 1-2 hours, and filtered to remove solid impurities, thereby obtaining the buffer.

[0035] Furthermore, the cage-like molecular composite crosslinking agent comprises the following components by weight percentage: 10-15% cage-like molecular organoboron component, 15-20% polyhydroxy compound, 20-25% hydroxycarboxylic acid compound, 1-5% high-valence metal compound, 0.5-2% inorganic base, and the balance being water; the structure of the cage-like molecular organoboron component is shown in formula (III):

[0036] .

[0037] Furthermore, the cage-like molecular organoboron component is prepared by the following steps:

[0038] A. An organoboron intermediate is generated by reacting ethylene glycol, n-butanol and boric acid, wherein the molar ratio of ethylene glycol, n-butanol and boric acid is 1:(0.4~0.6):(0.3~0.5), the reaction temperature is 110~120℃, the reaction is refluxed and the aqueous phase is separated using a water separator, the n-butanol phase is refluxed into the reactor, the reaction is carried out for 3~7h, and the solvent is removed by vacuum distillation to obtain the organoboron intermediate;

[0039] B. 1,3-adamantanediamine, an organoboron intermediate, and sodium hydroxide are reacted to generate a cage-like molecular organoboron component, wherein the mass ratio of 1,3-adamantanediamine to the organoboron intermediate is 1:(1.7-2.2), sodium hydroxide accounts for 2-4% of the total mass of the reactants, the reaction temperature is 140-150℃, and the reaction time is 4-6h, to obtain the cage-like molecular organoboron component;

[0040] The reaction formula is as follows:

[0041] .

[0042] Furthermore, the polyhydroxy compound is selected from any one or more of glycerol, sorbitol, and pentaerythritol; the hydroxycarboxylic acid compound is selected from any one or more of potassium citrate, sodium lactate, and sodium gluconate; the high-valence metal compound is selected from any one or a mixture of two of zirconium oxychloride and zirconium tetrachloride; and the inorganic base is selected from any one or more of sodium hydroxide, potassium hydroxide, and sodium carbonate.

[0043] Furthermore, the preparation method of the cage-like molecular composite crosslinking agent is as follows: under the conditions of a rotation speed of 100-200 r / min and a temperature of 50-60℃, a specified amount of water, a polyhydroxy compound, a hydroxycarboxylic acid compound, a high-valence metal compound, an inorganic base, and a cage-like molecular organic boron component are added in sequence and mixed. The mixture is stirred for 1-2 hours, and the solid impurities are removed by filtration to obtain the cage-like molecular composite crosslinking agent.

[0044] Furthermore, the de-gumming agent is selected from any one or more of ammonium persulfate, potassium persulfate, and sodium persulfate.

[0045] Secondly, the present invention provides a method for preparing ultra-high temperature, high-mineralization water-based guar gum fracturing fluid, which is achieved by the following technical solution.

[0046] A method for preparing the above-mentioned ultra-high temperature, high-mineralization water-based guar gum fracturing fluid, characterized by comprising the following steps:

[0047] S1. Under the condition of a rotation speed of 1000-1500 r / min, mix the specified amount of high mineralization water, cyclodextrin modified thickener, composite antioxidant, multi-effect adjuvant and bactericide, stir for 2-5 min, and place at 25℃ for 0.5-5 h to obtain the base liquid;

[0048] S2. Add the specified amounts of buffer, cage-like molecular composite crosslinking agent, and breaker to the base fluid and stir for 1-5 minutes to obtain ultra-high temperature, high mineralization water-based guar gum fracturing fluid.

[0049] This application has the following beneficial effects.

[0050] This invention introduces cyclodextrin and adamantane structures into the guar gum thickener and its matching crosslinking agent, respectively. This adds a novel supramolecular interaction of host-guest inclusion to the conventional chemical crosslinking between the thickener and crosslinking agent. Furthermore, the synergistic effect of buffers and composite antioxidants significantly improves the performance of high-salinity water-based guar gum fracturing fluid. It can withstand temperatures up to 200°C, can be directly prepared with high-salinity water, and achieves excellent fracture creation, proppant carrying, temperature and shear resistance, low filtration loss, and low damage, meeting the needs of fracturing operations in ultra-deep, ultra-high temperature, and low-permeability reservoirs in offshore and onshore oilfields. Whether evaluating the sand carrying capacity, filtration loss, temperature and shear resistance, and gel breaking performance of fracturing fluid in the laboratory according to the conditions specified in the industry standards "SY / T 7627-2021 Technical Requirements for Water-based Fracturing Fluids" and "SY / T 5185-2016 Performance Evaluation Method of Gravel Packing Sand Control Water-based Sand Carrying Fluid", or applying it in the high-temperature deep reservoirs of some offshore oilfields in the East China Sea, South China Sea, and Bohai Sea, the key performance of the ultra-high temperature and high salinity water-based guar gum fracturing fluid of this invention is superior to similar products at home and abroad, and its technical level has reached the leading level in China. Attached Figure Description

[0051] Figure 1 The figure shows the results of the temperature and shear resistance of the ultra-high temperature, high mineralization water-based guar gum fracturing fluid of this invention. Detailed Implementation

[0052] The present patent application will be further described below with reference to the embodiments. Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods. Unless otherwise specified, the materials used in the preparation process in the following embodiments have not undergone further processing and have been commercially available.

[0053] The hydroxypropyl-β-cyclodextrin used in the following embodiments of this application was purchased from Xi'an Lvteng Biotechnology Co., Ltd., with a molecular weight of 1431~1806 g / mol; hydroxypropyl guar gum was purchased from Shanxi Senrui Petroleum Technology Development Co., Ltd., grade 1 powder; tea polyphenols were purchased from Shaanxi Lantu Chenxi Biotechnology Co., Ltd., with a purity of 90%; fatty alcohol polyoxyethylene ether, nonylphenol polyoxyethylene ether, and fatty amine polyoxyethylene ether were purchased from Jiangsu Haian Petrochemical Plant, industrial grade; sodium polyacrylate, sodium polyepoxysuccinate, and sodium maleic acid-acrylic acid copolymer were purchased from Shandong Taihe Technology Co., Ltd., industrial grade.

[0054] Example 1: Preparation of Ultra-High Temperature High-Saltification Water-Based Guargum Fracturing Fluid A

[0055] (1) An organoboron intermediate was generated by reacting ethylene glycol, n-butanol and boric acid, wherein the amounts of ethylene glycol, n-butanol and boric acid added were 1860 kg, 889 kg and 556 kg respectively, the reaction temperature was 120 °C, the reaction was refluxed during the reaction, the aqueous phase was separated by a water separator, the n-butanol phase was refluxed into the reactor, the reaction was carried out for 3 h, the solvent was removed by vacuum distillation, and 970 kg of organoboron intermediate was obtained.

[0056] (2) 1,3-adamantanediamine, organoboron intermediate and sodium hydroxide were reacted to generate cage-like molecular organoboron component A-6. The amount of 1,3-adamantanediamine and organoboron intermediate added was 700 kg and 1190 kg respectively. Sodium hydroxide accounted for 2% of the total mass of the reactants. The reaction temperature was 140℃ and the reaction time was 6 h. 837 kg of cage-like molecular organoboron component A-6 was obtained.

[0057] (3) Using a 5000L reactor, under the conditions of 100r / min rotation speed and 50℃, 2350kg water, 750kg glycerol, 1000kg sodium lactate, 50kg zirconium oxychloride, 100kg sodium hydroxide and 750kg cage-like molecular organic boron component A-6 were added to the reactor in sequence, stirred for 2h, filtered to remove solid impurities, and cage-like molecular composite crosslinking agent A-1 was obtained.

[0058] (4) Using ethanol as solvent, 3-chloropropyltrimethoxysilane was reacted with hydroxypropyl-β-cyclodextrin to generate modified cyclodextrin A-7, wherein the mass of 3-chloropropyltrimethoxysilane and hydroxypropyl-β-cyclodextrin were 20 kg and 80 kg respectively, the reaction temperature was 80℃, the reaction time was 4 h, the mixture was filtered, washed 3 times with acetone, and dried under vacuum to obtain 90 kg of modified cyclodextrin A-7.

[0059] (5) Using ethanol as solvent and sodium hydroxide as alkalizing agent, modified cyclodextrin A-7 was reacted with hydroxypropyl guar gum to generate cyclodextrin modified thickener A-2. The mass of modified cyclodextrin A-7 and hydroxypropyl guar gum were 50 kg and 5000 kg, respectively. The reaction temperature was 60℃ and the reaction time was 2 h. The pH was adjusted to 6 with 10% hydrochloric acid. The mixture was filtered, washed three times with ethanol, and dried under vacuum to obtain 4900 kg of cyclodextrin modified thickener A-2.

[0060] (6) Using a 5000L reactor, under the conditions of 100r / min rotation speed and 60℃, 4050kg water, 500kg sodium maleic acid-acrylic acid copolymer, 250kg disodium ethylenediaminetetraacetate and 200kg sodium hydroxide were added to the reactor in sequence, stirred for 2h, filtered to remove solid impurities, and buffer A-3 was obtained.

[0061] (7) Using a 5000L reactor, under the conditions of 100r / min rotation speed and 50℃ temperature, 3700kg water, 50kg tea polyphenols, 750kg triethanolamine and 500kg sodium thiosulfate were added to the reactor in sequence, stirred for 2h, filtered to remove solid impurities, and the composite antioxidant A-4 was obtained.

[0062] (8) Using a 5000L reactor, under the conditions of 100r / min rotation speed and 50℃, 3725kg water, 500kg fatty alcohol polyoxyethylene ether, 25kg sodium perfluorononenoxybenzenesulfonate and 750kg benzyltrimethylammonium chloride were added to the reactor in sequence, stirred for 2h, filtered to remove solid impurities, and multi-effect excipient A-5 was prepared.

[0063] (9) Using a 1L Wu Yin stirrer, at a speed of 1500r / min, 491.5g of high-mineralization water (mineralization 20000mg / L), 3g of cyclodextrin modified thickener A-2, 1g of composite antioxidant A-4, 4g of multi-effect adjuvant A-5 and 0.5g of isothiazolinone were added sequentially, stirred for 3min, and placed at 25℃ for 0.5h to obtain the base liquid; 2g of buffer A-3, 2.5g of cage-like molecular composite crosslinking agent A-1 and 0.4g of ammonium persulfate were added to the base liquid and stirred for 1min to obtain ultra-high temperature high-mineralization water-based guar gum fracturing fluid A.

[0064] Example 2: Preparation of Ultra-High Temperature High-Saltification Water-Based Guargum Fracturing Fluid B

[0065] (1) An organoboron intermediate was generated by reacting ethylene glycol, n-butanol and boric acid, wherein the amounts of ethylene glycol, n-butanol and boric acid added were 931 kg, 667 kg and 463 kg respectively, the reaction temperature was 120 °C, the reaction was refluxed during the reaction, the aqueous phase was separated by a water separator, the n-butanol phase was refluxed into the reactor, the reaction was carried out for 7 h, the solvent was removed by vacuum distillation, and 863 kg of organoboron intermediate was obtained.

[0066] (2) 1,3-adamantanediamine, organoboron intermediate and sodium hydroxide were reacted to generate cage-like molecular organoboron component B-6, wherein the mass of 1,3-adamantanediamine and organoboron intermediate were 310 kg and 682 kg respectively, sodium hydroxide accounted for 4% of the total mass of reactants, the reaction temperature was 140℃ and the reaction time was 4 h, and 513 kg of cage-like molecular organoboron component B-6 was obtained.

[0067] (3) Using a 5000L reactor, under the conditions of a rotation speed of 200r / min and a temperature of 60℃, 2600kg of water, 750kg of sorbitol, 1000kg of sodium gluconate, 50kg of zirconium tetrachloride, 100kg of sodium carbonate and 500kg of cage-like molecular organic boron component B-6 were added to the reactor in sequence, stirred for 1h, filtered to remove solid impurities, and cage-like molecular composite crosslinking agent B-1 was obtained.

[0068] (4) Using ethanol as solvent, 3-chloropropyltrimethoxysilane was reacted with hydroxypropyl-β-cyclodextrin to generate modified cyclodextrin B-7, wherein the mass of 3-chloropropyltrimethoxysilane and hydroxypropyl-β-cyclodextrin were 20 kg and 120 kg respectively, the reaction temperature was 60℃, the reaction time was 6 h, the mixture was filtered, washed 3 times with acetone, and dried under vacuum to obtain 104 kg of modified cyclodextrin B-7.

[0069] (5) Using ethanol as solvent and sodium hydroxide as alkalizing agent, modified cyclodextrin B-7 was reacted with hydroxypropyl guar gum to generate cyclodextrin modified thickener B-2. The mass of modified cyclodextrin B-7 and hydroxypropyl guar gum were 90 kg and 1800 kg, respectively. The reaction temperature was 60℃ and the reaction time was 3 h. The pH was adjusted to 8 with 35% hydrochloric acid. The mixture was filtered, washed three times with ethanol, and dried under vacuum to obtain 1746 kg of cyclodextrin modified thickener B-2.

[0070] (6) Using a 5000L reactor, under the conditions of a rotation speed of 200r / min and a temperature of 60℃, 3800kg of water, 400kg of sodium polyacrylate, 500kg of hydroxyethyl ethylenediamine triacetate trisodium and 300kg of sodium carbonate were added to the reactor in sequence, stirred for 1h, filtered to remove solid impurities, and buffer B-3 was obtained.

[0071] (7) Using a 5000L reactor, under the conditions of 200r / min rotation speed and 60℃, 3725kg water, 25kg tea polyphenols, 750kg triethanolamine and 500kg sodium thiosulfate were added to the reactor in sequence, stirred for 1h, filtered to remove solid impurities, and the composite antioxidant B-4 was obtained.

[0072] (8) Using a 5000L reactor, under the conditions of a rotation speed of 200r / min and a temperature of 60℃, 3750kg of water, 600kg of nonylphenol polyoxyethylene ether, 50kg of sodium perfluorononenoxybenzenesulfonate and 600kg of benzyltrimethylammonium chloride were added to the reactor in sequence, stirred for 1h, filtered to remove solid impurities, and multi-effect excipient B-5 was prepared.

[0073] (9) Using a 1L Wu Yin stirrer, at a speed of 1000r / min, add 493g of high-mineralization water (mineralization 80000mg / L), 3g of cyclodextrin modified thickener B-2, 0.5g of composite antioxidant B-4, 3g of multi-effect adjuvant B-5 and 0.5g of polyhexamethylene biguanide, stir for 5min, and place at 25℃ for 4h to obtain the base liquid; add 2.5g of buffer B-3, 3g of cage-like molecular composite crosslinking agent B-1 and 0.4g of ammonium persulfate to the base liquid and stir for 5min to obtain ultra-high temperature high-mineralization water-based guar gum fracturing fluid B.

[0074] Example 3: Preparation of Ultra-High Temperature High-Saltification Water-Based Guargum Fracturing Fluid C

[0075] (1) An organoboron intermediate was generated by reacting ethylene glycol, n-butanol and boric acid. The amounts of ethylene glycol, n-butanol and boric acid added were 931 kg, 555 kg and 370 kg, respectively. The reaction temperature was 120 °C. During the reaction, the mixture was refluxed and the aqueous phase was separated using a water separator. The n-butanol phase was refluxed back into the reactor. The reaction was carried out for 5 h. The solvent was removed by vacuum distillation to obtain 710 kg of organoboron intermediate.

[0076] (2) 1,3-adamantanediamine, organoboron intermediate and sodium hydroxide were reacted to generate cage-like molecular organoboron component C-6, wherein the mass of 1,3-adamantanediamine and organoboron intermediate were 420 kg and 840 kg respectively, sodium hydroxide accounted for 3% of the total mass of reactants, the reaction temperature was 150℃ and the reaction time was 5 h, and 656 kg of cage-like molecular organoboron component C-6 was obtained.

[0077] (3) Using a 5000L reactor, under the conditions of 150r / min rotation speed and 55℃, 2525kg water, 750kg pentaerythritol, 1000kg sodium lactate, 75kg zirconium oxychloride, 50kg potassium hydroxide and 600kg cage-like molecular organic boron component C-6 were added to the reactor in sequence, stirred for 1.5h, filtered to remove solid impurities, and cage-like molecular composite crosslinking agent C-1 was obtained.

[0078] (4) Using ethanol as solvent, 3-chloropropyltrimethoxysilane was reacted with hydroxypropyl-β-cyclodextrin to generate modified cyclodextrin C-7, wherein the mass of 3-chloropropyltrimethoxysilane and hydroxypropyl-β-cyclodextrin were 20 kg and 100 kg respectively, the reaction temperature was 70℃, the reaction time was 5 h, the mixture was filtered, washed 3 times with acetone, and dried under vacuum to obtain 92 kg of modified cyclodextrin C-7.

[0079] (5) Using ethanol as solvent and sodium hydroxide as alkalizing agent, modified cyclodextrin C-7 was reacted with hydroxypropyl guar gum to generate cyclodextrin modified thickener C-2. The mass of modified cyclodextrin C-7 and hydroxypropyl guar gum were 80 kg and 800 kg, respectively. The reaction temperature was 40℃ and the reaction time was 4 h. The pH was adjusted to 7 with 30% hydrochloric acid. The mixture was filtered, washed three times with ethanol, and dried under vacuum to obtain 760 kg of cyclodextrin modified thickener C-2.

[0080] (6) Using a 5000L reactor, under the conditions of 150r / min rotation speed and 55℃, 4200kg water, 300kg sodium polyoxysuccinate, 300kg trisodium triacetate and 200kg potassium hydroxide were added to the reactor in sequence, stirred for 1.5h, filtered to remove solid impurities, and buffer C-3 was obtained.

[0081] (7) Using a 5000L reactor, under the conditions of 150r / min rotation speed and 55℃ temperature, 3495kg water, 5kg tea polyphenols, 900kg diethanolamine and 600kg sodium bisulfite were added to the reactor in sequence, stirred for 1.5h, filtered to remove solid impurities, and the composite antioxidant C-4 was obtained.

[0082] (8) Using a 5000L reactor, under the conditions of 150r / min rotation speed and 55℃, 3575kg water, 700kg fatty amine polyoxyethylene ether, 25kg sodium perfluorooctanoate and 700kg dodecyl dimethyl ammonium chloride were added to the reactor in sequence, stirred for 1.5h, filtered to remove solid impurities, and multi-effect excipient C-5 was prepared.

[0083] (9) Using a 1L Wu Yin stirrer, at a speed of 1500r / min, 493.25g of high-mineralization water (mineralization 40000mg / L), 2.75g of modified guar gum thickener C-2, 0.5g of composite antioxidant C-4, 3g of multi-effect adjuvant C-5 and 0.5g of dodecyl dimethyl benzyl ammonium chloride were added sequentially, stirred for 3min, and placed at 25℃ for 2h to obtain the base liquid; 2g of buffer C-3, 2.5g of cage-like molecular composite crosslinking agent C-1 and 0.4g of potassium persulfate were added to the base liquid and stirred for 3min to obtain ultra-high temperature high-mineralization water-based guar gum fracturing fluid C.

[0084] Example 4: Preparation of Ultra-High Temperature High-Saltification Water-Based Guargum Fracturing Fluid D

[0085] (1) An organoboron intermediate was generated by reacting ethylene glycol, n-butanol and boric acid, wherein the masses of ethylene glycol, n-butanol and boric acid were 1117 kg, 733 kg and 500 kg respectively, the reaction temperature was 120 °C, the reaction was refluxed and condensed during the reaction, the aqueous phase was separated by a water separator, the n-butanol phase was refluxed into the reactor, the reaction was carried out for 4 h, the solvent was removed by vacuum distillation, and 967 kg of organoboron intermediate was obtained.

[0086] (2) 1,3-adamantanediamine, organoboron intermediate and sodium hydroxide were reacted to generate cage-like molecular organoboron component D-6, wherein the mass of 1,3-adamantanediamine and organoboron intermediate were 550 kg and 935 kg respectively, sodium hydroxide accounted for 4% of the total mass of reactants, the reaction temperature was 150℃ and the reaction time was 4 h, and 829 kg of cage-like molecular organoboron component D-6 was obtained.

[0087] (3) Using a 5000L reactor, under the conditions of 100r / min rotation speed and 60℃, 2250kg water, 750kg glycerol, 1100kg sodium gluconate, 100kg zirconium tetrachloride, 50kg sodium hydroxide and 750kg cage-like molecular organic boron component D-6 were added to the reactor in sequence, stirred for 2h, filtered to remove solid impurities, and cage-like molecular composite crosslinking agent D-1 was obtained.

[0088] (4) Using ethanol as solvent, 3-chloropropyltrimethoxysilane was reacted with hydroxypropyl-β-cyclodextrin to generate modified cyclodextrin D-7, wherein the mass of 3-chloropropyltrimethoxysilane and hydroxypropyl-β-cyclodextrin were 40 kg and 160 kg, respectively, the reaction temperature was 60℃, the reaction time was 6 h, the mixture was filtered, washed 3 times with acetone, and dried under vacuum to obtain 154 kg of modified cyclodextrin D-7.

[0089] (5) Using ethanol as solvent and sodium hydroxide as alkalizing agent, modified cyclodextrin D-7 was reacted with hydroxypropyl guar gum to generate cyclodextrin modified thickener D-2. The mass of modified cyclodextrin D-7 and hydroxypropyl guar gum were 8 kg and 800 kg, respectively. The reaction temperature was 40℃ and the reaction time was 4 h. The pH was adjusted to 6.5 with 25% hydrochloric acid, filtered, washed 3 times with ethanol, and vacuum dried to obtain 776 kg of cyclodextrin modified thickener D-2.

[0090] (6) Using a 5000L reactor, under the conditions of 100r / min rotation speed and 60℃, 4000kg of water, 400kg of sodium maleic acid-acrylic acid copolymer, 300kg of trisodium hydroxyethyl ethylenediamine triacetate and 300kg of sodium carbonate were added to the reactor in sequence, stirred for 2h, filtered to remove solid impurities, and buffer D-3 was obtained.

[0091] (7) Using a 5000L reactor, under the conditions of 100r / min rotation speed and 50℃ temperature, 3450kg water, 50kg tea polyphenols, 1000kg monoethanolamine and 500kg sodium isoascorbate were added to the reactor in sequence, stirred for 2h, filtered to remove solid impurities, and the composite antioxidant D-4 was obtained.

[0092] (8) Using a 5000L reactor, under the conditions of 100r / min rotation speed and 50℃ temperature, 3950kg water, 500kg fatty alcohol polyoxyethylene ether, 50kg sodium perfluorooctanoate and 500kg dimethyl diallyl ammonium chloride were added to the reactor in sequence, stirred for 2h, filtered to remove solid impurities, and multi-effect excipient D-5 was prepared.

[0093] (9) Using a 1L Wu Yin stirrer, at a speed of 1500r / min, 491.5g of high-mineralization water (mineralization 30000mg / L), 3g of modified guar gum thickener D-2, 1g of composite antioxidant D-4, 4g of multi-effect adjuvant D-5 and 0.5g of dodecyl dimethyl benzyl ammonium chloride were added sequentially, stirred for 3min, and placed at 25℃ for 4h to obtain the base liquid; 2g of buffer D-3, 2.5g of cage-like molecular composite crosslinking agent D-1 and 0.4g of ammonium persulfate were added to the base liquid and stirred for 2min to obtain ultra-high temperature high-mineralization water-based guar gum fracturing fluid D.

[0094] Example 5: Preparation of Ultra-High Temperature High-Mineralization Water-Based Guargum Fracturing Fluid E

[0095] (1) An organoboron intermediate was generated by reacting ethylene glycol, n-butanol and boric acid, wherein the amounts of ethylene glycol, n-butanol and boric acid added were 1365 kg, 733 kg and 476 kg respectively, the reaction temperature was 120 °C, the reaction was refluxed and condensed during the reaction, the aqueous phase was separated by a water separator, the n-butanol phase was refluxed into the reactor, the reaction was carried out for 3 h, the solvent was removed by vacuum distillation, and 872 kg of organoboron intermediate was obtained.

[0096] (2) 1,3-adamantanediamine, organoboron intermediate and sodium hydroxide were reacted to generate cage-like molecular organoboron component E-6, wherein the mass of 1,3-adamantanediamine and organoboron intermediate were 360 ​​kg and 792 kg respectively, sodium hydroxide accounted for 3% of the total mass of reactants, the reaction temperature was 140℃ and the reaction time was 6 h, and 602 kg of cage-like molecular organoboron component E-6 was obtained.

[0097] (3) Using a 5000L reactor, under the conditions of 200r / min rotation speed and 60℃, 2525kg water, 800kg pentaerythritol, 1000kg potassium citrate, 50kg zirconium oxychloride, 25kg potassium hydroxide and 600kg cage-like molecular organic boron component E-6 were added to the reactor in sequence, stirred for 1h, filtered to remove solid impurities, and cage-like molecular composite crosslinking agent E-1 was obtained.

[0098] (4) Using ethanol as a solvent, 3-chloropropyltrimethoxysilane was reacted with hydroxypropyl-β-cyclodextrin to generate modified cyclodextrin E-7, wherein the mass of 3-chloropropyltrimethoxysilane and hydroxypropyl-β-cyclodextrin were 40 kg and 240 kg, respectively, the reaction temperature was 80℃, the reaction time was 4 h, the mixture was filtered, washed 3 times with acetone, and dried under vacuum to obtain 216 kg of modified cyclodextrin E-7.

[0099] (5) Using ethanol as solvent and sodium hydroxide as alkalizing agent, modified cyclodextrin E-7 was reacted with hydroxypropyl guar gum to generate cyclodextrin modified thickener E-2, wherein the mass of modified cyclodextrin E-7 and hydroxypropyl guar gum were 100 kg and 2000 kg respectively, the reaction temperature was 40℃, the reaction time was 4 h, the pH was adjusted to 7.5 with 25% hydrochloric acid, filtered, washed 3 times with ethanol, and vacuum dried to obtain 1930 kg of cyclodextrin modified thickener E-2.

[0100] (6) Using a 5000L reactor, under the conditions of 200r / min rotation speed and 60℃, 4100kg water, 300kg sodium polyoxysuccinate, 300kg trisodium hydroxyethyl ethylenediamine triacetate and 300kg sodium hydroxide were added to the reactor in sequence, stirred for 1h, filtered to remove solid impurities, and buffer E-3 was obtained.

[0101] (7) Using a 5000L reactor, under the conditions of 200r / min rotation speed and 60℃, 3720kg water, 30kg tea polyphenols, 750kg triethanolamine and 500kg sodium thiosulfate were added to the reactor in sequence, stirred for 1h, filtered to remove solid impurities, and the composite antioxidant E-4 was obtained.

[0102] (8) Using a 5000L reactor, under the conditions of 200r / min rotation speed and 60℃, 3950kg water, 500kg fatty amine polyoxyethylene ether, 50kg sodium perfluorohexanoate and 500kg dodecyl dimethyl ammonium chloride were added to the reactor in sequence, stirred for 1h, filtered to remove solid impurities, and multi-effect adjuvant E-5 was prepared.

[0103] (9) Using a 1L Wu Yin stirrer, at a speed of 1000r / min, add 493g of high-mineralization water (mineralization 60000mg / L), 3g of cyclodextrin modified thickener E-2, 0.5g of composite antioxidant E-4, 3g of multi-effect adjuvant E-5 and 0.5g of isothiazolinone, stir for 5min, and place at 25℃ for 4h to obtain the base liquid; add 2.5g of buffer E-3, 3g of cage-like molecular composite crosslinking agent E-1 and 0.4g of ammonium persulfate to the base liquid and stir for 3min to obtain ultra-high temperature high-mineralization water-based guar gum fracturing fluid E.

[0104] Performance evaluation of ultra-high temperature, high-mineralization water-based guar gum fracturing fluids prepared in Examples 1-5:

[0105] Seawater samples were collected from an oilfield in the western South China Sea (water quality data are shown in Table 1) to prepare a seawater-based high-temperature guar gum fracturing fluid. Based on the standards "SY / T 7627-2021 Technical Requirements for Water-Based Fracturing Fluids" and "SY / T 5185-2016 Performance Evaluation Method for Gravel-Packed Sand Control Water-Based Propellant Fluids," a high-temperature, high-pressure filtration analyzer, rheometer, and high-speed centrifuge were used to evaluate the proppant carrying capacity, filtration loss, temperature and shear resistance, and gel breaking performance (residue content) of the ultra-high temperature, high-salinity water-based guar gum fracturing fluid. Other experimental conditions: static proppant carrying test temperature 95℃; static filtration loss, temperature and shear resistance, and gel breaking test temperatures 200℃; no gel breaking agent was added in the temperature and shear resistance test. The experimental results are shown in Table 2.

[0106] Table 1. Water quality data of seawater samples from an oilfield in the western South China Sea.

[0107]

[0108] Table 2. Experimental Results of Performance Evaluation of Ultra-High Temperature High-Salinity Fracturing Fluid

[0109]

[0110] *Foreign manufacturers' sample formula: 0.8% thickener, 1% temperature stabilizer, 0.4% pH adjuster, 1% crosslinking agent, 1% demulsifier, anti-swelling and drainage aid; add 0.6% demulsifier during demulsification.

[0111] From Table 2 and Figure 1 The data shows that the ultra-high temperature and high salinity fracturing fluid of this invention, under the experimental temperature of 200℃, meets the requirements of offshore oilfield and industry standards in terms of static filtration performance, temperature and shear resistance, and gel breaking performance. Under the same conditions, its sand carrying capacity, filtration performance, temperature and shear resistance, and gel breaking performance are all superior to ultra-high temperature and high salinity fracturing fluid products from other foreign manufacturers.

[0112] The embodiments described herein are preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape, and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A high-temperature, high-mineralization water-based guar gum fracturing fluid, characterized in that: The mixture comprises a base liquid, a buffer, a cage-like molecular composite crosslinking agent, and a degumming agent in a mass ratio of 100:(0.1-0.6):(0.2-0.8):(0.01-0.08); the base liquid comprises the following components in weight percentage: 0.55-0.6% cyclodextrin-modified thickener, 0.1-0.6% composite antioxidant, 0.4-0.8% multi-effect adjuvant, 0.1-0.2% bactericide, and the balance being high-mineralized water with a mineralization of 20000 mg / L to 80000 mg / L; The cyclodextrin-modified thickener is prepared by the following steps: a. Using ethanol as a solvent, 3-chloropropyltrimethoxysilane is reacted with hydroxypropyl-β-cyclodextrin to generate a modified cyclodextrin having the structure of formula (I); wherein, the mass ratio of 3-chloropropyltrimethoxysilane to hydroxypropyl-β-cyclodextrin is 1:(4~6), the reaction temperature is 60~80℃, and the reaction time is 4~6h, to obtain the modified cyclodextrin; (I) R1= or Among them, at least two R1s are ; b. Using ethanol as solvent and sodium hydroxide as alkalizing agent, modified cyclodextrin is reacted with hydroxypropyl guar gum to generate a cyclodextrin-modified thickener with the structure of formula (II); wherein the mass ratio of modified cyclodextrin to hydroxypropyl guar gum is (1-10):100, the reaction temperature is 40-60℃, the reaction time is 2-4h, and the pH of the system is adjusted to 6-8 to obtain the cyclodextrin-modified thickener; （Ⅱ） R2= or Of these, at least two R2 values ​​are Guar represents the hydroxypropyl guar gum structure; The cage-like molecular composite crosslinking agent comprises the following components by weight percentage: 10-15% cage-like molecular organoboron component, 15-20% polyhydroxy compound, 20-25% hydroxycarboxylic acid compound, 1-5% high-valence metal compound, 0.5-2% inorganic base, and the balance being water; the structure of the cage-like molecular organoboron component is shown in formula (III). （Ⅲ）。 2. The ultra-high temperature, high-mineralization water-based guar gum fracturing fluid according to claim 1, characterized in that: The composite antioxidant comprises the following components by weight percentage: 0.1-1% tea polyphenols, 15-20% alcohol amine compounds, 10-15% reducing agent, and the balance being water; the alcohol amine compounds are selected from any one or more of monoethanolamine, diethanolamine, and triethanolamine; the reducing agent is selected from any one or more of sodium isoascorbate, sodium bisulfite, and sodium thiosulfate.

3. The ultra-high temperature, high-mineralization water-based guar gum fracturing fluid according to claim 1, characterized in that: The multi-effect adjuvant comprises the following components by weight percentage: 10-15% polyether demulsifier, 0.5-2% fluorocarbon discharge aid, 10-15% clay stabilizer, and the balance being water; the polyether demulsifier is selected from any one or more of fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, and fatty amine polyoxyethylene ether; the fluorocarbon discharge aid is selected from any one or more of sodium perfluorononenoxybenzenesulfonate, sodium perfluorooctanoate, and sodium perfluorohexanoate; and the clay stabilizer is selected from any one or more of benzyltrimethylammonium chloride, didodecyldimethylammonium chloride, and dimethyldiallylammonium chloride.

4. The ultra-high temperature, high-mineralization water-based guar gum fracturing fluid according to claim 1, characterized in that: The buffer comprises the following components by weight percentage: 5-10% copolymer chelating agent, 5-10% aminocarboxylic acid chelating agent, 4-8% inorganic base, and the balance being water; the copolymer chelating agent is selected from any one or more of sodium polyacrylate, sodium maleate-acrylic acid copolymer, and sodium polyepoxysuccinate; the aminocarboxylic acid chelating agent is selected from any one or more of disodium ethylenediaminetetraacetate, trisodium nitroglycerin triacetate, and trisodium hydroxyethylethylenediaminetriacetate; and the inorganic base is any one or more of sodium hydroxide, potassium hydroxide, and sodium carbonate.

5. The ultra-high temperature, high-mineralization water-based guar gum fracturing fluid according to claim 1, characterized in that: The cage-like molecular organoboron component is prepared by the following steps: A. An organoboron intermediate is generated by reacting ethylene glycol, n-butanol and boric acid, wherein the molar ratio of ethylene glycol, n-butanol and boric acid is 1:(0.4~0.6):(0.3~0.5), the reaction temperature is 110~120℃, the reaction is refluxed and the aqueous phase is separated using a water separator, the n-butanol phase is refluxed into the reactor, the reaction is carried out for 3~7h, and the solvent is removed by vacuum distillation to obtain the organoboron intermediate; B. 1,3-adamantanediamine, an organoboron intermediate, and sodium hydroxide are reacted to generate a cage-like molecular organoboron component, wherein the mass ratio of 1,3-adamantanediamine to the organoboron intermediate is 1:(1.7-2.2), sodium hydroxide accounts for 2-4% of the total mass of the reactants, the reaction temperature is 140-150℃, and the reaction time is 4-6h, to obtain the cage-like molecular organoboron component.

6. The ultra-high temperature, high-mineralization water-based guar gum fracturing fluid according to claim 1, characterized in that: The polyhydroxy compound is selected from any one or more of glycerol, sorbitol, and pentaerythritol; the hydroxycarboxylic acid compound is selected from any one or more of potassium citrate, sodium lactate, and sodium gluconate; the high-valence metal compound is selected from any one or a mixture of two of zirconium oxychloride and zirconium tetrachloride; and the inorganic base is selected from any one or more of sodium hydroxide, potassium hydroxide, and sodium carbonate.

7. The ultra-high temperature, high-mineralization water-based guar gum fracturing fluid according to claim 1, characterized in that: The bactericide is selected from any one or more of dodecyl dimethyl benzyl ammonium chloride, isothiazolinone, and polyhexamethylene biguanide; the degreasing agent is selected from any one or more of ammonium persulfate, potassium persulfate, and sodium persulfate.

8. A method for preparing the ultra-high temperature, high-mineralization water-based guar gum fracturing fluid according to any one of claims 1-7, characterized in that: Includes the following steps: S1. Under the condition of a rotation speed of 1000-1500 r / min, mix the specified amount of high mineralization water, cyclodextrin modified thickener, composite antioxidant, multi-effect adjuvant and bactericide, stir for 2-5 min, and place at 25℃ for 0.5-5 h to obtain the base liquid; S2. Add the specified amounts of buffer, cage-like molecular composite crosslinking agent, and breaker to the base fluid and stir for 1-5 minutes to obtain ultra-high temperature, high mineralization water-based guar gum fracturing fluid.

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