CN103113486A - Sulfonic acid modified carboxymethyl hydroxypropyl guar gum and its preparation method and application - Google Patents

Abstract

The invention relates to sulfonic acid modified carboxymethyl hydroxypropyl guar gum and a preparation method and application thereof, wherein the sulfonic acid modified carboxymethyl hydroxypropyl guar gum is prepared from guar gumThe structural formula of the gel is as follows:

Description

Sulfonic acid modified carboxymethyl hydroxypropyl guar gum and its preparation method and application

technical field

The invention relates to a sulfonic acid modified carboxymethyl hydroxypropyl guar gum and its preparation method and application, and the application specifically refers to its use in preparing fracturing fluid.

Background technique

Polymer thickeners for plant gum fracturing fluid systems mainly include guar gum, coumarin, cellulose and their chemically modified products (such as hydroxypropyl guar gum, carboxymethyl hydroxypropyl guar gum, etc.), Due to the high viscosity of guar gum, low price, simple on-site operation, and low friction, it is widely used in large areas. However, due to the high content of raw powder residue, reaching 19% to 28%, the gel-breaking residue and residual polymer of this type of fracturing fluid It can block the diversion channels formed by the proppant to varying degrees, reducing the effect of oil and gas well stimulation.

Sandstone reservoirs are generally anionic systems. The developed anionic vegetable gums have good compatibility with reservoirs, good water solubility, strong thickening ability, can be used at low concentrations, low water insolubles, and good thermal stability. And resistant to biodegradation. In order to achieve the purpose of multi-purpose in one dose, the main substances in guar gum that produce insolubles and gel-breaking residues - protein and cellulose are chemically hydrolyzed and grafted to make them more easily chemically and biologically degradable and contain prophylaxis. The new substance of water-based sulfonate, the introduction of long-chain organic sulfonate into the structure of carboxymethyl guar gum, can play the role of drainage aid, and at the same time combine the cost factor of vegetable gum, the carboxymethyl hydroxypropyl guar Glue sulfonation to prepare vegetable gum is an effective method with versatility. The fracturing fluid formed by the modified thickener produces less residue and polymer residue after the gel is broken, and the fracturing fluid formed by the cross-linking agent The cross-linked network structure is more prone to oxidative degradation, so it has less damage to the reservoir and fracture conductivity. At the same time, the modified product contains a hydrophilic degradable biosurfactant, which has the characteristics of demulsification and low surface interfacial tension, and the formed fracturing fluid does not need to add demulsifiers and drainage aids, which can save The amount of chemical agent used.

Contents of the invention

An object of the present invention is to provide a sulfonic acid modified carboxymethyl hydroxypropyl guar gum, the guar gum has high thickening efficiency, low surface and interfacial tension, easy gel breaking, and facilitates flowback.

Another object of the present invention is to provide a preparation method of the sulfonic acid modified carboxymethyl hydroxypropyl guar gum.

The third object of the present invention is to provide the application of the sulfonic acid modified carboxymethyl hydroxypropyl guar gum in the preparation of fracturing fluid

The fourth object of the present invention is to provide a fracturing fluid prepared from the sulfonic acid modified carboxymethyl hydroxypropyl guar gum.

For reaching above-mentioned object, on the one hand, the invention provides a kind of sulfonic acid modified carboxymethyl hydroxypropyl guar gum, and its structural formula is as follows:

Wherein, R=H, n=0, 1, 2 or 3; or, R=OH, n=an integer of 0-6.

In order to provide sulfonic acid-modified carboxymethyl hydroxypropyl guar gum with better performance and effect, n is preferably 0 or 1 in the present invention.

Carboxymethyl hydroxypropyl guar fracturing fluid system is a fracturing fluid system with low concentration, low damage and high temperature resistance. Disadvantages of this system are salt tolerance (eg KCl) and narrow pH range for crosslinking. The invention improves the salt tolerance and surface activity of the carboxymethyl hydroxypropyl guar gum by appropriately modifying the sulfonic acid group.

According to a specific embodiment of the present invention, the sulfonic acid group substitution degree of the sulfonic acid modified carboxymethyl hydroxypropyl guar gum of the present invention is 0.01～0.2;

Among them, the substitution degree of sulfonic acid group is more preferably 0.027-0.18.

The substitution degree mentioned in the present invention is the molar substitution degree.

According to the specific embodiment of the present invention, the present invention preferably wherein the carboxymethyl substitution degree is 0.12-0.25, and the hydroxypropyl substitution degree is 0.15-0.4.

According to a specific embodiment of the present invention, it is further preferred in the present invention that the molecular weight of the sulfonic acid-modified carboxymethyl hydroxypropyl guar gum is 1.6 million to 2 million.

Wherein the molecular weight of sulfonic acid modified carboxymethyl hydroxypropyl guar gum is the weight average molecular weight.

On the other hand, the present invention also provides the preparation method of described guar gum, comprises the steps:

(1) Carboxymethyl hydroxypropyl guar gum is added to the reaction vessel, and the aqueous solution of alcohol is added;

(2) Under nitrogen atmosphere, add aqueous sodium hydroxide solution dropwise, stir and heat up to 65-80°C, add sulfonating agent dropwise, and react for 3-10 hours;

(3) Then adjust the pH of the solution to 7 with acid, filter, collect and dry the solid to obtain a light yellow powder, which is organic sulfonic acid modified carboxymethyl hydroxypropyl guar gum.

The alcohol aqueous solution can refer to the alcohol aqueous solution of similar reaction in the prior art, but according to the specific embodiment of the present invention, preferably the alcohol aqueous solution is ethanol aqueous solution or isopropanol aqueous solution.

The concentration of the aqueous alcohol solution can refer to the concentration of the aqueous alcohol solution in similar reactions in the prior art, but according to a specific embodiment of the present invention, the concentration of the aqueous alcohol solution is preferably 50% to 80% by mass.

In the present invention, it is further preferred that the concentration of the aqueous sodium hydroxide solution is 10-30%, more preferably 15%.

In the present invention, it is also preferable that the stirring temperature rise in step (2) is to heat up to 70°C;

In order to further optimize the reaction of the present invention, the present invention preferably stirs for 0.5 h after adding the aqueous sodium hydroxide solution dropwise in step (2), and then raises the temperature to 65-80° C. with stirring.

Even more preferably, after stirring to raise the temperature to 65-80° C., stirring for 0.5 h, and then adding the sulfonating agent dropwise.

The present invention further preferably has a reaction time of step (2) of 3 hours.

In the present invention, the further preferred step (2) sodium hydroxide dripping time is 0.5h.

The dropping time of the sulfonating agent is preferably 0.5-2 hours.

The type of the sulfonating agent can be based on the target compound, using the corresponding sulfonating agent commonly used in the art, and according to specific embodiments of the present invention, preferably the sulfonating agent is vinylsulfonic acid or 3-chloro-2- Sodium Hydroxypropanesulfonate.

The amount of the sulfonating agent can be determined according to the amount of similar sulfonation reactions in the art, and according to specific embodiments of the present invention, when preferably the sulfonating agent is vinyl sulfonic acid, vinyl sulfonic acid: carboxymethyl hydroxy Propyl guar gum: the mass ratio of NaOH is (2-45): 200: (1.5-35);

When described sulfonating agent is 3-chloro-2-hydroxypropanesulfonate sodium, 3-chloro-2-hydroxypropanesulfonate: carboxymethyl hydroxypropyl guar gum: the mass ratio of NaOH is (4-80 ):200: (1.5-35).

The sulfonic acid group is an anionic group, and the carboxymethyl group is also an anionic group. When one anionic group has been connected to the molecular chain, the other anionic group is repelled by the same charge. It is difficult to connect and the conversion rate is low. However, the present invention perfectly solves the above-mentioned problems by controlling the degree of substitution of the reactants and the addition amount of the sulfonic acid etherification agent.

The acid in the step (3) of the present invention can be an acid commonly used in the art to adjust the pH value, such as organic acid or inorganic acid. Those skilled in the art can select an appropriate acid to adjust the pH value according to the reaction described in the specification of the present invention. Wherein the present invention preferably adopts hydrochloric acid, acetic acid or citric acid.

In the third aspect, the present invention also provides the application of the sulfonic acid modified carboxymethyl hydroxypropyl guar gum in the preparation of fracturing fluid.

In the fourth aspect, the present invention also provides the fracturing fluid prepared from the sulfonic acid modified carboxymethyl hydroxypropyl guar gum.

The concentration of the guar gum in the fracturing fluid can refer to the concentration in the prior art, and according to a specific embodiment of the present invention, the concentration of the sulfonic acid modified carboxymethyl hydroxypropyl guar gum is preferably mass percent 0.1% to 0.3%.

The components of the fracturing fluid can be prepared with reference to other fracturing fluids in the prior art. Those skilled in the art can easily obtain the fracturing fluid described in the present invention according to the description of the present invention and in combination with the fracturing fluid of the prior art. liquid.

In the present invention, it is further preferred that the fracturing fluid also contains the following components in mass percentage: 0.2-1% of cross-linking agent, 0.15-0.4% of cross-linking accelerator, and 0.25-0.4% of anti-swelling agent.

Wherein the cross-linking agent can be a cross-linking agent commonly used in preparing fracturing fluid in the field, and in the present invention, organic boron, organic zirconium or organic titanium is preferred.

Among them, cross-linking accelerator and anti-swelling agent are also common cross-linking accelerators and anti-swelling agents for preparing fracturing fluids in this field, and those skilled in the art do not need to pay more creative work when selecting cross-linking accelerators and anti-swelling agents .

For example, commonly used cross-linking accelerators can be sodium hydroxide, sodium carbonate and sodium bicarbonate and the like.

Commonly used anti-swelling agents can be potassium chloride, ammonium chloride and polyquaternium salt.

In summary, the present invention provides a sulfonic acid modified carboxymethyl hydroxypropyl guar gum, its use, preparation method and fracturing fluid prepared therefrom. Guar gum provided by the present invention has the following advantages:

1, the organosulphonic acid modified carboxymethyl hydroxypropyl guar gum prepared by the present invention has certain surface activity, has enough high viscosity and lower surface activity when operation construction, simultaneously salt-resistant (Fig. 1 investigated The sulfonic acid hydroxypropyl guar gum (0.6%) of embodiment 1 is respectively in the viscosity situation of 0～0.5%NaCl and KCl, as can be seen from the figure, the viscosity is affected very little by 0～0.5% salt), High temperature resistance, easy biodegradation, easy cross-linking, low viscosity after gel breaking, low surface tension of gel breaking fluid, less residue, easy flowback, and can be popularized and applied in oil fields.

2. The organic sulfonic acid modified carboxymethyl hydroxypropyl guar gum prepared by the present invention has good water solubility, small fluid loss coefficient, good fluid loss performance, and multifunctionality itself. The internal energy becomes a low-viscosity fluid, which can completely flow back, reduce the types of additives, and greatly reduce the damage of fracturing fluid to the reservoir.

3. The organic sulfonic acid modified carboxymethyl hydroxypropyl guar gum prepared by the present invention introduces long-chain organic sulfonate in the structure, which can play the role of drainage aid, and simultaneously combines the cost factor of vegetable gum to convert carboxymethyl The fracturing fluid formed by sulfonating hydroxypropyl guar gum to prepare vegetable gum does not need to add demulsifiers and drainage aids, which can save the amount of chemical agents.

Description of drawings

Fig. 1 is the change figure of the viscosity of sulfoethyl substituted carboxymethyl hydroxypropyl guar gum of embodiment 1.

Fig. 2 is the molecular weight distribution spectrum of the sulfoethyl substituted carboxymethyl hydroxypropyl guar gum in Example 1, the molecular weight Mn = 1.585 million.

Fig. 3 is the molecular weight distribution spectrum of the carboxymethyl hydroxypropyl guar gum substituted with hydroxysulfopropyl group in Example 2, the molecular weight Mn=1.888 million.

Figures 2 and 3 are drawn using BI-DNDC differential refractometer detection.

Figure 4 is the NMR spectrum of the sulfoethyl substituted carboxymethyl hydroxypropyl guar gum of Example 1: the degree of carboxymethyl substitution is 0.12 to 0.25, the degree of substitution of hydroxypropyl is 0.15 to 0.4, and the degree of substitution of sulfonic acid group : 0.01～0.1.

Fig. 5 is the NMR spectrum of the carboxymethyl hydroxypropyl guar gum substituted with hydroxysulfopropyl group in Example 2: the degree of substitution of carboxymethyl group is 0.12-0.25, the degree of substitution of hydroxypropyl group is 0.15-0.4, and the degree of substitution of sulfonic acid group is 0.05 ~0.15.

Detailed ways

The implementation process and beneficial effects of the present invention are described in detail below through specific examples, aiming to help readers better understand the essence and characteristics of the present invention, and not as a limitation to the scope of implementation of this case.

Example 1:

A preparation method of organic sulfonic acid modified carboxymethyl hydroxypropyl guar gum, the steps are as follows:

(1) In the reactor that 3L65% ethanol solution is housed, add 1000.0g carboxymethyl hydroxypropyl guar gum (the degree of substitution of carboxymethyl is 0.19, the degree of substitution of hydroxypropyl is 0.28);

(2) Under a nitrogen atmosphere, add 150 g of 15% sodium hydroxide aqueous solution dropwise, stir for 0.5 hours, then heat up to 65-70° C., stir for 0.5 hours, add 68 g of vinylsulfonic acid dropwise, keep the temperature at 70° C., and complete the dropwise addition in 2 hours. Continue stirring for 4 hours;

(3) neutralize the reaction solution with hydrochloric acid to pH = 7, filter, and dry the solid product at 70°C to obtain the light yellow powder product SCMHPG;

In this structure R=H, n=0.

Determination of special performance indicators of products:

(1) Molecular weight determination:

Using a gel chromatography system combined with a multi-angle laser light scattering instrument, the mobile phase: 0.1N NaNO ₃ aqueous solution, PLAquagelOH series gel column as the separation column, the sample concentration is 0.70‰, and the molecular weight of the product is determined;

(2) Determination of surface and interfacial tension:

K100C automatic surface tensiometer to measure surface interfacial tension;

(3) Determination of dynamic damage performance:

Crush the coal, pass it through a 100-mesh sieve, weigh 30g of coal powder and put it into the core holder, press it under 6MPa pressure for 10min, set aside, use 2% KCl to measure the permeability, and the gel breaker is damaged;

(4) Measurement of viscosity affected by salt content: investigate the viscosity situation of sulfoethyl substituted carboxymethyl hydroxypropyl guar gum (0.6%) in 0～0.5% NaCl and KCl respectively in this embodiment, as can be seen from the figure , the viscosity is very little affected by 0～0.5% salt, other examples have also done the same experiment, and obtain the curve with consistent trend of change, illustrate that the viscosity of sulfonic acid modified carboxymethyl hydroxypropyl guar gum of the present invention is all Little affected by salt.

Product performance test results:

(1) product number-average molecular weight: 1.585 million (Fig. 2 is the molecular weight distribution collection of sulfoethyl substituted carboxymethyl hydroxypropyl guar gum, molecular weight Mn=158.5;

(2) Sulfonic acid group substitution degree: 0.027 (Fig. 4 is the NMR spectrum of sulfoethyl substituted carboxymethyl hydroxypropyl guar gum: carboxymethyl substitution degree is 0.12～0.25, hydroxypropyl substitution degree is 0.15～0.4, Substitution degree of sulfonic acid group: 0.01～0.1);

(3) Apparent viscosity (0.6%): 109.5mPa·s;

(4) The product is formulated into an aqueous solution with a mass fraction of 0.12%, viscosity: 12mPa.s;

(4.1) Viscosity after crosslinking: 360mPa.s;

静态初滤失量Qsp＝1.27×10^-3m³/m²，滤失速率V＝2.25×10^-4m/min；(4.2) Static filtration performance: static filtration performance filtration coefficient

Static initial fluid loss Qsp=1.27×10 ^-3 m ³ /m ² , fluid loss rate V=2.25×10 ^-4 m/min;

(4.3) Injury rate of coal seam: 12.6%;

(4.4) Surface tension: 31.54mN/m, interfacial tension: 2.20mN/m;

(4.5) Gel breaking in the presence of ammonium persulfate (0.5‰)-sodium sulfite (0.5‰), residue after breaking: 54.0mg/L, viscosity of breaking liquid: 1.60mPa.s.

Example 2:

A preparation method of organic sulfonic acid modified carboxymethyl hydroxypropyl guar gum, comprising the following steps successively:

(1) In the reactor that 3L65% isopropanol solution is housed, add 1000.0g carboxymethyl hydroxypropyl guar gum (the degree of substitution of carboxymethyl is 0.16, the degree of substitution of hydroxypropyl is 0.23);

(2) Under nitrogen atmosphere, 110g of 30% sodium hydroxide aqueous solution was added dropwise, and the temperature was raised to 80° C. after stirring for 0.5 hours, stirred for 0.5 hours, 250 g of 40% 3-chloro-2-hydroxypropanesulfonate aqueous solution was added dropwise, and kept The temperature is at 80°C, the dropwise addition is completed in 1.5 hours, and the stirring is continued for 5 hours;

(3) Neutralize the reaction solution with 5% hydrochloric acid to pH = 7, filter, and dry the solid product at 70°C to obtain a light yellow powder;

In this structure R=OH, n=1.

Determination of special performance indicators of products:

(1) Molecular weight determination:

Using a gel chromatography system combined with a multi-angle laser light scattering instrument, the mobile phase: 0.1N NaNO ₃ aqueous solution, PLAquagelOH series gel column as the separation column, the sample concentration is 0.70‰, and the molecular weight of the product is determined;

(2) Determination of surface and interfacial tension:

K100C automatic surface tensiometer to measure surface interfacial tension;

(3) Determination of dynamic damage performance:

Crush the coal, pass through a 100-mesh sieve, weigh 30g of coal powder and put it into the core holder, press it under 6MPa pressure for 10min, and set aside, use 2% KCl to measure the permeability, and the side of the gel-breaking fluid is damaged;

(4) Measurement of viscosity affected by salt content: investigate the viscosity situation of hydroxysulfopropyl substituted carboxymethyl hydroxypropyl guar gum (0.6%) in 0～0.5% NaCl and KCl respectively in this embodiment, obtain the change with Fig. 1 The curves with the same trend indicate that the viscosity of the hydroxysulfopropyl substituted carboxymethyl hydroxypropyl guar gum in this embodiment is less affected by the salt content.

Product performance test results:

(1) product number-average molecular weight: 1.888 million (Fig. 3 is the molecular weight distribution collection of hydroxysulfopropyl substituted carboxymethyl hydroxypropyl guar gum, molecular weight Mn=1.888 million);

(2) Sulfonic acid group substitution degree: 0.11 (Figure 5 is the NMR spectrum of hydroxysulfopropyl substituted carboxymethyl hydroxypropyl guar gum: carboxymethyl substitution degree is 0.12～0.25, hydroxypropyl substitution degree is 0.15～0.4 , sulfonic acid group substitution degree 0.05～0.15);

(3) Apparent viscosity (0.6%): 105.2mPa·s;

(4) The product is formulated into an aqueous solution with a mass fraction of 0.12%, viscosity: 15mPa.s;

(4.1) Viscosity after crosslinking: 300mPa.s;

静态初滤失量Qsp＝5.79×10^-3m³/m²，滤失速率V＝7.51×10^-4m/min；(4.2) Static filtration performance: filtration coefficient

Static initial fluid loss Qsp=5.79×10 ^-3 m ³ /m ² , fluid loss rate V=7.51×10 ^-4 m/min;

(4.3) Injury rate of coal seam: 18.5%;

(4.4) Surface tension: 32.78mN/m; Interfacial tension: 3.10mN/m;

(4.5) Gel breaking in the presence of ammonium persulfate (0.5‰)-sodium sulfite (0.5‰), residue after breaking: 58.0mg/L, viscosity 1.80mPa.s.

When the organic sulfonic acid modified carboxymethyl hydroxypropyl guar gum is used as a thickening agent for fracturing, the use concentration is 0.1%-0.3% (m/m).

Example 3:

A preparation method of organic sulfonic acid modified carboxymethyl hydroxypropyl guar gum, the steps are as follows:

(1) In the reactor that 3L65% ethanol solution is housed, add 1000.0g carboxymethyl hydroxypropyl guar gum (the degree of substitution of carboxymethyl group is 0.12, the degree of substitution of hydroxypropyl group is 0.35);

(2) Under a nitrogen atmosphere, add dropwise 360 g of 30% aqueous sodium hydroxide solution, stir for 0.5 hours and then heat up to 80° C., stir for 0.5 hour, add dropwise 650 g of 40% 3-chloro-2-hydroxypropanesulfonate aqueous solution, and keep The temperature is at 80°C, the dropwise addition is completed in 1.5 hours, and the stirring is continued for 5 hours;

(3) Neutralize the reaction solution with 5% citric acid to pH = 7, filter, and dry the solid product at 70°C to obtain the light yellow powder product SCMHPG;

In this structure R=OH, n=1.

Determination of special performance indicators of products:

(1) Molecular weight determination:

Using a gel chromatography system combined with a multi-angle laser light scattering instrument, the mobile phase: 0.1N NaNO ₃ aqueous solution, PLAquagelOH series gel column as the separation column, the sample concentration is 0.70‰, and the molecular weight of the product is determined;

(2) Determination of surface and interfacial tension:

K100C automatic surface tensiometer to measure surface interfacial tension;

(3) Dynamic damage performance:

Crush the coal, pass it through a 100-mesh sieve, weigh 30g of coal powder and put it into the core holder, press it under 6MPa pressure for 10min, set aside, use 2% KCl to measure the permeability, and the gel breaker is damaged;

(4) Measurement of viscosity affected by salt content: investigate the viscosity situation of hydroxysulfopropyl substituted carboxymethyl hydroxypropyl guar gum (0.6%) in 0～0.5% NaCl and KCl respectively in this embodiment, obtain the change with Fig. 1 The curves with the same trend indicate that the viscosity of the hydroxysulfopropyl substituted carboxymethyl hydroxypropyl guar gum in this embodiment is less affected by the salt content.

Product performance test results:

(1) Number average molecular weight of the product: 1.65 million;

(2) Substitution degree of sulfonic acid group: 0.18;

(3) Apparent viscosity (0.6%): 97.9mPa·s;

(4) The product is formulated into an aqueous solution with a mass fraction of 0.12%, viscosity: 12mPa.s;

(4.1) Viscosity after crosslinking: 134mPa.s;

(4.2) Static filtration performance Static filtration performance:

静态初滤失量Qsp＝2.67×10^-3m³/m²，滤失速率V＝2.16×10^-4m/min；Filter loss coefficient

Static initial fluid loss Qsp=2.67×10 ^-3 m ³ /m ² , fluid loss rate V=2.16×10 ^-4 m/min;

(4.3) Injury rate of coal seam: 21.0%;

(4.4) Surface tension: 27.54mN/m, interfacial tension: 2.05mN/m;

(4.5) Gel breaking in the presence of ammonium persulfate (0.5‰)-sodium sulfite (0.5‰), residue after breaking: 53.0mg/L, viscosity: 1.70mPa.s.

Example 4:

A preparation method of organic sulfonic acid modified carboxymethyl hydroxypropyl guar gum, the steps are as follows:

(1) In the reactor that 3L65% ethanol solution is housed, add 1000.0g carboxymethyl hydroxypropyl guar gum (the degree of substitution of carboxymethyl is 0.15, the degree of substitution of hydroxypropyl is 0.32);

(2) Under a nitrogen atmosphere, add 325 g of 40% sodium hydroxide aqueous solution dropwise, stir for 0.5 hours, then heat up to 65-70° C., stir for 0.5 hours, add 360 g of vinylsulfonic acid dropwise, keep the temperature at 70° C., and complete the dropwise addition in 2 hours. Continue stirring for 4 hours;

(3) neutralize the reaction solution with hydrochloric acid to pH = 7, filter, and dry the solid product at 70°C to obtain the light yellow powder product SCMHPG;

In this structure R=H, n=0.

Determination of special performance indicators of products:

(1) Determination of molecular weight:

Using a gel chromatography system combined with a multi-angle laser light scattering instrument, the mobile phase: 0.1N NaNO ₃ aqueous solution, PLAquagelOH series gel column as the separation column, the sample concentration is 0.70‰, and the molecular weight of the product is determined;

(2) Determination of surface and interfacial tension:

K100C automatic surface tensiometer to measure surface interfacial tension;

(3) Determination of dynamic damage performance:

Crush the coal, pass it through a 100-mesh sieve, weigh 30g of coal powder and put it into the core holder, press it under 6MPa pressure for 10min, set aside, use 2% KCl to measure the permeability, and the gel breaker is damaged;

(4) Viscosity is affected by the change measurement of salt: investigate the viscosity situation of sulfoethyl substituted carboxymethyl hydroxypropyl guar gum (0.6%) in 0～0.5% NaCl and KCl respectively in this embodiment, obtain and Fig. 1 change trend The same curve shows that the viscosity of the sulfoethyl substituted carboxymethyl hydroxypropyl guar gum in this embodiment is less affected by the salt content.

Product performance test results:

(1) Number average molecular weight of the product: 1.64 million;

(2) Substitution degree of sulfonic acid group: 0.25;

(3) Apparent viscosity (0.6%): 105.3mPa·s;

(4) The product is formulated into an aqueous solution with a mass fraction of 0.12%, viscosity: 10.5mPa·s;

(4.1) Viscosity after crosslinking: 36mPa.s;

Due to the high degree of substitution of sulfonic acid groups in the product of this example, its cross-linking performance becomes poor, and the performance of the cross-linking jelly cannot meet the requirements of actual fracturing construction.

Claims (10)

1. a sulfonic acid modified carboxymethyl hydroxypropyl guar gum, is characterized in that, its structural formula is as follows: Wherein, R=H, n=0, 1, 2 or 3; or, R=OH, n=0-6. 2. The sulfonic acid modified carboxymethyl hydroxypropyl guar gum according to claim 1, characterized in that the molecular weight of the sulfonic acid modified carboxymethyl hydroxypropyl guar gum is 1.6 to 2 million. 3. sulfonic acid modified carboxymethyl hydroxypropyl guar gum according to claim 1 or 2, is characterized in that, wherein the degree of substitution of sulfonic acid group is 0.01～0.2, and the degree of substitution of carboxymethyl group is 0.12～0.25, The degree of substitution of hydroxypropyl group is 0.15-0.4. 4. the preparation method of the sulfonic acid modified carboxymethyl hydroxypropyl guar gum described in any one of claims 1 to 3, is characterized in that, the method comprises the steps: (1) adding carboxymethyl hydroxypropyl guar gum to the reaction vessel, adding the aqueous solution of alcohol, stirring and dissolving; preferably the alcohol is ethanol or isopropanol; (2) Under nitrogen atmosphere, add sodium hydroxide aqueous solution dropwise, preferably dropwise for 0.5h, stir and heat up to 65-80°C, preferably rise to 70°C, dropwise add sulfonating agent, preferably dropwisely for 0.5-2h, react for 3~ 10 hours, preferably reacted for 3 hours; (3) Then lower the temperature to 30-40° C., adjust the pH of the solution to 7 with acid, filter, collect and dry the solid to obtain a light yellow powder, which is the sulfonic acid-modified carboxymethylhydroxypropyl guar gum. 5. method according to claim 4, it is characterized in that: the concentration of the aqueous solution of described alcohol is mass percent 50%～80%, and weight consumption is 5～8 times of carboxymethyl hydroxypropyl guar gum weight; The concentration of the aqueous sodium hydroxide solution is 10% to 30%, preferably 15%. 6. The method according to claim 4, characterized in that: the sulfonating agent is vinylsulfonic acid or sodium 3-chloro-2-hydroxypropanesulfonate. 7. method according to claim 4, is characterized in that: when described sulfonating agent is vinylsulfonic acid, vinylsulfonic acid: carboxymethyl hydroxypropyl guar gum: the mass ratio of NaOH is (2- 45):200:(1.5-35); When described sulfonating agent is 3-chloro-2-hydroxypropanesulfonate sodium, 3-chloro-2-hydroxypropanesulfonate: carboxymethyl hydroxypropyl guar gum: the mass ratio of NaOH is (4-80 ):200: (1.5-35). 8. The application of the sulfonic acid modified carboxymethyl hydroxypropyl guar gum described in any one of claims 1 to 3 in the preparation of fracturing fluid. 9. A fracturing fluid, characterized in that the fracturing fluid comprises the sulfonic acid-modified carboxymethylhydroxypropyl guar gum according to any one of claims 1-3. 10. The fracturing fluid according to claim 9, characterized in that the concentration of the sulfonic acid modified carboxymethyl hydroxypropyl guar gum in the fracturing fluid is 0.1%-0.3% by mass.

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