CN104194766A - Clean fracturing fluid and preparation method thereof - Google Patents

Abstract

The invention discloses a clean fracturing fluid which comprises crude rubber fluid, viscosity accelerant and gel breaker, the crude rubber fluid comprises the following materials by mass percent: 0.1%-0.5% of hydrophobic association polyacrylamide, 0.05%-0.2% of organic acid, 0.1%-0.8% of clay stabilizer and the balance of water; the viscosity accelerant comprises the following materials according to mass percent: 0.05%-0.4% of alkyl amine oxide, 0.1%-0.5% of Gemini surfactant, 0.1%-1.0% of alkyl lower alcohol, 0.05%-0.4% of pH regulator, and the balance of water; the volume ratio of the crude rubber fluid to the viscosity accelerant is 100:(5-10), and the mass of the gel breaker is 0.005%-0.05% that of the clean fracturing fluid. The invention further provides a preparation method of the clean fracturing fluid. The long-term technical problems of high cost and poor temperature resistance performance of the clean fracturing fluid are solved.

Description

A kind of clean fracturing fluid and preparation method thereof

technical field

The invention belongs to the technical field of petrochemical industry, and in particular relates to a clean fracturing fluid and a preparation method thereof.

Background technique

Fracturing is a major measure for increasing production of oil and gas wells and increasing injection of water wells. Fracturing fluids are divided into water-based fracturing fluids, oil-based fracturing fluids, foam fracturing fluids and clean fracturing fluids. Water-based guar gum fracturing fluid is the main fracturing fluid used in low-permeability and ultra-low-permeability oilfields. The fracturing effect statistics show that the fracturing fluid has many kinds of additives, large residue of gel-breaking fluid, short stable production period after fracturing, poor fracturing effect and complicated fluid preparation process.

VES cationic surfactant type clean fracturing fluid is a polymer-free fracturing fluid system, which has the advantages of no residue and good anti-swelling effect of clay. A revolutionary change in technology, it is considered the highest level of water-based fracturing fluid technology. However, its disadvantages are cation adsorption, high cost (1.5%-6% addition), and low temperature resistance (≤70°C), which limit the application and scale of this fracturing fluid in the field.

The fracturing fluid reported in patent ZL201110374771.3 is a non-cationic surfactant type fracturing fluid. This fracturing fluid overcomes the damage caused by the adsorption of VES cationic fracturing fluid, and at the same time endows the gel-breaking and oil-displacement effect. It is a composite and efficient fracturing fluid system, but its disadvantages are (1) the amount of additives is large and the cost is high ; (2) The temperature resistance of the fracturing fluid is poor (≤80°C), therefore, the fracturing fluid cannot fully meet the performance requirements of on-site fracturing construction for the fracturing fluid.

Luo Pingya and others reported an associative hydrophobic-based polymer fracturing fluid, which is a cross-linked fracturing fluid system obtained by modifying acrylamide. The biggest advantages of this fracturing fluid are low residue, good shear resistance, and significantly improved temperature resistance (below 120°C), but the disadvantages are (1) the solid powder thickener dissolves slowly in water when the liquid is mixed on site. "Fish eyes" are easy to appear; (2) when the amount of thickener increases to 0.4%, the viscosity of the original glue is greater than 90mPa·s, and it is difficult to pump liquid during on-site construction; (3) the amount added is high, and the cost is high. The above shortcomings limit its large-scale application.

Throughout the development of fracturing fluids at home and abroad, low-cost, low-damage, high-temperature-resistant and composite fracturing fluids are still the development direction of fracturing working fluids in the future.

Contents of the invention

The technical problem to be solved by the present invention is to provide a clean fracturing fluid for the above-mentioned deficiencies in the prior art. The clean fracturing fluid not only avoids the performance defects of polymer fracturing fluid and surfactant fracturing fluid through reasonable proportioning, but also takes into account their respective advantages to realize the combination of polymer fracturing fluid and surfactant fracturing fluid. The scientific combination of the fracturing fluid can significantly improve the performance.

In order to solve the above-mentioned technical problems, the technical solution adopted in the present invention is: a clean fracturing fluid, characterized in that it consists of a raw glue solution, a viscosity accelerator and a gel breaker, and the raw glue solution consists of the following raw materials in mass percentage Made: 0.1% to 0.5% of hydrophobic association polyacrylamide, 0.05% to 0.2% of organic acid, 0.1% to 0.8% of clay stabilizer, and the balance is water; the viscosity accelerator is made of the following raw materials in mass percentage : 0.05%～0.4% of alkyl amine oxide, 0.1%～0.5% of Gemini surfactant, 0.1%～1.0% of alkyl low-carbon alcohol, 0.05%～0.4% of pH regulator, and the balance is water; the original gum The volume ratio of fluid and viscosity accelerator is 100:(5～10), and the quality of gel breaker is 0.005%～0.05% of clean fracturing fluid quality; Described organic acid is petroleum sulfonic acid, fatty alcohol sulfuric acid, ethylene glycol One or more of amine tetraacetic acid, citric acid, oxalic acid and sulfamic acid, the clay stabilizer is NH ₄ Cl or KCl; the alkyl lower alcohol is methanol, butanol or amyl alcohol, and the pH regulator is Triethanolamine, diethanolamine, ethanolamine, NaOH, KOH, K ₂ CO ₃ , Na ₂ CO ₃ or NaHCO ₃ ; the breaker is ammonium persulfate or chlorine dioxide.

The above-mentioned clean fracturing fluid is characterized in that the original gum solution is made of the following raw materials in mass percentage: 0.1% to 0.3% of hydrophobically associated polyacrylamide, 0.05% to 0.1% of organic acid, clay stabilizer 0.2%-0.6%, the balance is water; the viscosity accelerator is made of the following raw materials in mass percentage: 0.1%-0.3% of alkyl amine oxide, 0.2%-0.4% of Gemini surfactant, and alkyl low-carbon alcohol 0.3% to 0.8%, pH regulator 0.1% to 0.3%, and water as the balance; the quality of the gel breaker is 0.03% to 0.05% of the clean fracturing fluid.

The above-mentioned clean fracturing fluid is characterized in that the raw gum solution is made of the following raw materials in mass percentage: 0.2% of hydrophobic association polyacrylamide, 0.08% of organic acid, 0.5% of clay stabilizer, and the balance is Water; the viscosity accelerator is made of the following raw materials in mass percentage: 0.15% of alkyl amine oxide, 0.3% of Gemini surfactant, 0.5% of alkyl low-carbon alcohol, 0.15% of pH regulator, and the balance is water; The quality of the gel breaker is 0.04% of the clean fracturing fluid.

The above-mentioned clean fracturing fluid is characterized in that the hydrophobic association polyacrylamide is FRAC-102 associate thickener (Xi'an Kali Oilfield Technology Co., Ltd.), FRA-313 associate thickener (Beijing Frick Technology Development Company), GRF-1 associative non-crosslinked fracturing fluid thickener (Sichuan Guangya Polymer Chemical Co., Ltd.), CGR-7 association thickener (Chengdu Jianxiangshu Crown Technology Co., Ltd.) or SXT102 thickener for fracturing (Beijing Xitao Technology Development Co., Ltd.).

The aforementioned clean fracturing fluid is characterized in that the alkyl amine oxide is octadecyl dihydroxyethyl amine oxide, hexadecyl dihydroxyethyl amine oxide, hexadecyl dimethyl oxide amine, octadecyldimethylamine oxide, or stearylamidopropylamine oxide.

In addition, the present invention also provides a method for preparing the above-mentioned clean fracturing fluid, which is characterized in that the method comprises the following steps:

Step 1, uniformly mixing hydrophobically associated polyacrylamide, clay stabilizer, organic acid and water to obtain the original glue solution;

Step 2, mixing the alkyl amine oxide, Gemini surfactant, alkyl low-carbon alcohol and pH regulator evenly to obtain a viscosity accelerator;

Step 3: Mix the original glue solution described in step 1 and the viscosity accelerator described in step 2, and then stir for 1 to 5 minutes. During construction, add a gel breaker to the stirred mixture and mix evenly to obtain a clean fracturing fluid.

When the clean fracturing fluid of the present invention is used, it is pumped into oil wells carrying proppant according to conventional methods.

Compared with the prior art, the present invention has the following advantages:

1. The clean fracturing fluid of the present invention has low production cost, little damage, and excellent performance, which solves the problems of high-temperature addition of polymer fracturing fluid, difficulty in on-site liquid preparation and poor use effect; improves the performance of surfactant-based fracturing fluid. The temperature resistance ability reduces the amount of addition, reduces the cost of fracturing fluid, and solves the long-standing technical problems such as high cost of clean fracturing fluid and poor temperature resistance.

2. The organic acid in the clean fracturing fluid of the present invention can ensure that when the hydrophobic association polyacrylamide is used at a high concentration, the viscosity of the original glue solution is kept below 60mPa·s, so as to facilitate the pumpability of the original glue solution for on-site fracturing construction , which solves the problem of difficulty in transportation and the problem of affecting the quality of the fracturing fluid caused by the excessive viscosity of the original glue solution when the hydrophobic association polymer fracturing fluid is used at high concentrations; in addition, the salt formed after the organic acid is combined with the pH regulator It greatly improves the temperature resistance of the fracturing fluid, and can also produce a synergistic effect with the hydrophobic association polyacrylamide to increase the viscosity of the fracturing fluid.

3. The organic acid in the clean fracturing fluid of the present invention has a strong complexation effect on calcium ions in water, which alleviates the problem of performance degradation of hydrophobically associated polyacrylamide when encountering calcium ions.

4. The pH regulator in the clean fracturing fluid of the present invention not only neutralizes the organic acid, but also ensures the gelation of the fracturing fluid in an alkaline environment (pH=8-9), increasing the viscosity of the fracturing fluid.

5. A synergistic effect is produced between the Gemini surfactant in the clean fracturing fluid of the present invention and the hydrophobically associated polyacrylamide, which not only reduces the concentration of polymers and surfactants used, but also improves the temperature resistance of the fracturing fluid. And the viscosity can be significantly improved.

6. The clean fracturing fluid of the present invention relies on the oxidized gel breaker to degrade the hydrophobically associated polyacrylamide with a certain viscosity, and uses crude oil to destroy the micellar structure formed by the surfactant and the hydrophobically associated polyacrylamide, finally realizing fracturing The liquid is completely broken.

7. The alkyl lower-carbon alcohol in the clean fracturing fluid of the present invention not only increases the solubility and dispersibility of the Gemini surfactant, but also has a defoaming effect.

8. The clean fracturing fluid of the present invention not only avoids the defects of the respective performances of polymer fracturing fluid and surfactant fracturing fluid through reasonable proportioning, but also realizes polymer fracturing fluid and surface active agent taking into account their respective advantages. The scientific combination of multi-agent fracturing fluid has significantly improved the performance of the fracturing fluid.

The technical solutions of the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments.

Description of drawings

Fig. 1 is a shear curve diagram of the clean fracturing fluid in Example 1 of the present invention.

Fig. 2 is a shear curve diagram of the clean fracturing fluid in Example 3 of the present invention.

Fig. 3 is a shear curve diagram of the clean fracturing fluid in Example 5 of the present invention.

Detailed ways

Example 1

The clean fracturing fluid of this embodiment is composed of raw gum solution, viscosity accelerator and gel breaker, and the raw gum solution is made of the following raw materials in mass percentage: 0.2% of hydrophobically associated polyacrylamide, 0.08% of organic acid , clay stabilizer 0.5%, and the balance is water; Described viscosity accelerator is made of the raw material of following mass percent: hexadecyl dihydroxyethyl amine oxide 0.15%, Gemini surfactant (sulfonate type Gemini surface active agent Activator) 0.3%, alkyl low-carbon alcohol 0.5%, pH regulator 0.15%, and the balance is water; the volume ratio of the original glue solution and the viscosity accelerator is 100:8, and the quality of the gel breaker is clean pressure 0.04% of the split liquid quality; the hydrophobic association polyacrylamide is FRAC-102 association thickener (purchased from Xi'an Kali Oilfield Technology Co., Ltd); the organic acid is petroleum sulfonic acid, and the clay is stable The agent is NH ₄ Cl, the alkyl lower alcohol is methanol, the pH regulator is triethanolamine, and the gel breaker is ammonium persulfate.

The preparation method of the clean fracturing fluid of the present embodiment is:

Step 1. Uniformly mix FRAC-102 associate thickener, clay stabilizer NH ₄ Cl, organic acid petroleum sulfonic acid and water to obtain the original glue solution;

Step 2, mixing cetyl dihydroxyethyl amine oxide, Gemini surfactant, methanol and triethanolamine evenly to obtain a viscosity accelerator;

Step 3: Mix the original glue solution described in step 1 and the viscosity accelerator described in step 2, and then stir for 5 minutes. During construction, add a gel breaker to the stirred mixture, and mix evenly to obtain a clean fracturing fluid.

When the clean fracturing fluid in this embodiment is used, it is pumped into the oil well carrying proppant according to conventional methods.

Fig. 1 is a shear curve diagram of the clean fracturing fluid of this embodiment. It can be seen from the figure that the viscosity of the clean fracturing fluid in this example is ≥40 mPa·s after continuous shearing at 120° C. and 170 s ⁻¹ for 80 minutes.

Example 2

This example is the same as Example 1, except that the hydrophobic association polyacrylamide is FRA-313 association thickener (Beijing Freike Technology Development Company), GRF-1 association non- Cross-linked fracturing fluid thickener (Sichuan Guangya Polymer Chemical Co., Ltd.), CGR-7 associate thickener (Chengdu Jianxiang Shuguan Technology Co., Ltd.) or SXT102 fracturing thickener (Beijing Xitao Technology Development Co., Ltd.), the alkyl amine oxide is octadecyl dihydroxyethyl amine oxide, hexadecyl dimethyl amine oxide, octadecyl dimethyl amine oxide or octadecyl amidopropyl amine oxide Amines, the organic acid being fatty alcohol sulfuric acid, ethylenediaminetetraacetic acid, citric acid, oxalic acid or sulfamic acid, or petroleum sulfonic acid, fatty alcohol sulfuric acid, ethylenediaminetetraacetic acid, citric acid, oxalic acid and sulfamic acid At least two of them, the alkyl lower alcohol is butanol or pentanol, the clay stabilizer is KCl, and the pH regulator is diethanolamine, ethanolamine, ammonia water, NaOH, KOH, K ₂ CO ₃ , Na ₂ CO ₃ or NaHCO ₃ , the breaker is chlorine dioxide.

Example 3

The clean fracturing fluid of this embodiment is composed of raw gum solution, viscosity accelerator and gel breaker, and the raw gum solution is made of the following raw materials in mass percentage: 0.3% of hydrophobically associated polyacrylamide, 0.1% of organic acid , clay stabilizer 0.6%, and the balance is water; Described viscosity accelerator is made of the raw material of following mass percent: hexadecyl dimethyl amine oxide 0.1%, Gemini surfactant (quaternary ammonium salt type Gemini surfactant agent) 0.2%, alkyl low-carbon alcohol 0.8%, pH regulator 0.3%, and the balance is water; the volume ratio of the original glue solution and the viscosity accelerator is 100:5, and the quality of the gel breaker is clean fracturing 0.03% of the liquid mass; the hydrophobic association polyacrylamide is GRF-1 association type non-crosslinked fracturing fluid thickener (purchased from Sichuan Guangya Polymer Chemical Co., Ltd); the organic acid is petroleum sulfonic acid A mixture of acid and fatty alcohol sulfuric acid (the mass ratio of petroleum sulfonic acid and fatty alcohol sulfuric acid is 1:1), the alkyl lower alcohol is pentanol, the clay stabilizer is KCl, and the pH regulator is NaOH , the breaker is chlorine dioxide.

The preparation method of the clean fracturing fluid of the present embodiment is:

Step 1. Uniformly mix GRF-1 associative non-crosslinked fracturing fluid thickener, clay stabilizer KCl, petroleum sulfonic acid, fatty alcohol sulfuric acid and water to obtain the original gum solution;

Step 2, mixing cetyl dimethyl amine oxide, Gemini surfactant, amyl alcohol and NaOH evenly to obtain a viscosity accelerator;

Step 3: Mix the raw glue solution described in step 1 and the viscosity accelerator described in step 2, and then stir for 3 minutes. During construction, add a gel breaker to the stirred mixture, and mix evenly to obtain a clean fracturing fluid.

When the clean fracturing fluid in this embodiment is used, it is pumped into the oil well carrying proppant according to conventional methods.

Fig. 2 is a shear curve diagram of the clean fracturing fluid of this embodiment. It can be seen from the figure that the viscosity of the clean fracturing fluid in this example is ≥40 mPa·s after continuous shearing for 80 min at 110° C. and 170 s ⁻¹ .

Example 4

This example is the same as Example 3, except that the hydrophobic association polyacrylamide is FRAC-102 associate thickener (Xi'an Kali Oilfield Technology Co., Ltd.), FRA-313 associate thickener Thickening agent (Beijing Frick Technology Development Co., Ltd.), CGR-7 associate thickener (Chengdu Jianxiang Shuguan Technology Co., Ltd.) or SXT102 thickener for fracturing (Beijing Xitao Technology Development Co., Ltd.). The alkyl amine oxide is octadecyl dihydroxyethyl amine oxide, hexadecyl dihydroxyethyl amine oxide, octadecyl dimethyl amine oxide or octadecylamidopropyl amine oxide, and the organic acid One or more of petroleum sulfonic acid, fatty alcohol sulfuric acid, ethylenediaminetetraacetic acid, citric acid, oxalic acid and aminosulfonic acid, or fatty alcohol sulfuric acid, ethylenediaminetetraacetic acid, citric acid, oxalic acid and amino Two of the sulfonic acids, or one of ethylenediaminetetraacetic acid, citric acid, oxalic acid and sulfamic acid and petroleum sulfonic acid, the alkyl low-carbon alcohol is methanol or butanol, and the clay stabilizer NH ₄ Cl, the pH regulator is triethanolamine, diethanolamine, ethanolamine, ammonia water, KOH, K ₂ CO ₃ , Na ₂ CO ₃ or NaHCO ₃ , and the breaker is ammonium persulfate.

Example 5

The clean fracturing fluid of this embodiment is composed of raw gum solution, viscosity accelerator and gel breaker, and the raw gum solution is made of the following raw materials in mass percentage: 0.1% of hydrophobically associated polyacrylamide, 0.05% of organic acid , 0.2% clay stabilizer, and the balance is water; the viscosity accelerator is made of the following raw materials in mass percent: octadecyl dihydroxyethyl amine oxide 0.3%, Gemini surfactant (polyethylene type nonionic Gemini Surfactant) 0.4%, alkyl lower carbon alcohol 0.3%, pH adjuster 0.1%, surplus is water; The volume ratio of described original glue solution and viscosity accelerator is 100:10, and the quality of breaker is clean 0.05% of the fracturing fluid quality; the hydrophobic association polyacrylamide is FRA-313 association thickener (purchased from Beijing Freike Technology Development Company); the organic acid is petroleum sulfonic acid and citric acid Mixture (the mass ratio of petroleum sulfonic acid and citric acid is 2:1), described alkyl low-carbon alcohol is butanol, and described clay stabilizer is KCl, and described pH adjusting agent is ethanolamine, and described breaker is Ammonium persulfate.

The preparation method of the clean fracturing fluid of the present embodiment is:

Step 1. Mix FRA-313 associate thickener, clay stabilizer KCl, petroleum sulfonic acid, fatty alcohol sulfuric acid, citric acid and water to obtain the original gum solution;

Step 2, mixing octadecyl dihydroxyethyl amine oxide, Gemini surfactant, butanol and ethanolamine evenly to obtain a viscosity accelerator;

Step 3: Mix the original glue solution described in step 1 and the viscosity accelerator described in step 2, and then stir for 1 min. During construction, add a gel breaker to the stirred mixture, and mix evenly to obtain a clean fracturing fluid.

When the clean fracturing fluid in this embodiment is used, it is pumped into the oil well carrying proppant according to conventional methods.

Fig. 3 is a shear curve diagram of the clean fracturing fluid of this embodiment. It can be seen from the figure that the viscosity of the clean fracturing fluid in this example is ≥40 mPa·s after continuous shearing for 80 min at 100°C and 170 s ⁻¹ .

Example 6

This example is the same as Example 5, except that the hydrophobic association polyacrylamide is FRAC-102 association thickener (Xi'an Kali Oilfield Technology Co., Ltd.), GRF-1 association non- Cross-linked fracturing fluid thickener (Sichuan Guangya Polymer Chemical Co., Ltd.), CGR-7 associate thickener (Chengdu Jianxiang Shuguan Technology Co., Ltd.) or SXT102 fracturing thickener (Beijing Xitao Technology Development Co., Ltd.), the alkyl amine oxide is cetyl dihydroxyethyl amine oxide, cetyl dimethyl amine oxide, octadecyl dimethyl amine oxide or octadecyl amidopropyl amine oxide amine, the organic acid is one or more of petroleum sulfonic acid, fatty alcohol sulfuric acid, ethylenediaminetetraacetic acid, citric acid, oxalic acid and sulfamic acid, or fatty alcohol sulfuric acid, ethylenediaminetetraacetic acid, Two of citric acid, oxalic acid and sulfamic acid, or a mixture of fatty alcohol sulfuric acid, ethylenediaminetetraacetic acid, oxalic acid and sulfamic acid and petroleum sulfonic acid, and the alkyl low-carbon alcohol is methanol or amyl alcohol, the clay stabilizer is NH ₄ Cl, the pH regulator is triethanolamine, diethanolamine, ammonia, NaOH, KOH, K ₂ CO ₃ , Na ₂ CO ₃ or NaHCO ₃ , the breaker for chlorine dioxide.

Example 7

The clean fracturing fluid of this embodiment is composed of raw gum solution, viscosity accelerator and gel breaker, and the raw gum solution is made of the following raw materials in mass percentage: 0.2% of hydrophobically associated polyacrylamide, 0.08% of organic acid , clay stabilizer 0.5%, and the balance is water; Described viscosity accelerator is made of the raw material of following mass percent: octadecyl dimethyl amine oxide 0.15%, Gemini surfactant (quaternary ammonium salt type Gemini surfactant agent) 0.3%, alkyl low-carbon alcohol 0.5%, pH regulator 0.15%, and the balance is water; the volume ratio of the original glue solution and the viscosity accelerator is 100:10, and the quality of the gel breaker is clean fracturing 0.05% of the liquid mass; the hydrophobic association polyacrylamide is FRA-313 association thickener (purchased from Beijing Freike Technology Development Company); the organic acid is a mixture of oxalic acid and sulfamic acid (oxalic acid The mass ratio of sulfamic acid and sulfamic acid is 3:1), the alkyl low-carbon alcohol is methanol, the clay stabilizer is NH ₄ Cl, the pH regulator is NaHCO ₃ , and the breaker is dioxide chlorine.

The preparation method of the clean fracturing fluid of the present embodiment is:

Step 1. Mix FRA-313 associate thickener, clay stabilizer NH ₄ Cl, oxalic acid, sulfamic acid and water evenly to obtain the original glue solution;

Step 2, mixing octadecyl dimethyl amine oxide, Gemini surfactant, methanol and _NaHCO3 uniformly to obtain a viscosity accelerator;

Step 3: Mix the original glue solution described in step 1 and the viscosity accelerator described in step 2, and then stir for 1 min. During construction, add a gel breaker to the stirred mixture, and mix evenly to obtain a clean fracturing fluid.

When the clean fracturing fluid in this embodiment is used, it is pumped into the oil well carrying proppant according to conventional methods.

Example 8

This example is the same as Example 7, except that the hydrophobic association polyacrylamide is FRAC-102 association thickener (Xi'an Kali Oilfield Technology Co., Ltd.), GRF-1 association non- Cross-linked fracturing fluid thickener (Sichuan Guangya Polymer Chemical Co., Ltd.), CGR-7 associate thickener (Chengdu Jianxiang Shuguan Technology Co., Ltd.) or SXT102 fracturing thickener (Beijing Xitao Technology Development Co., Ltd.), the alkyl amine oxide is octadecyl dihydroxyethyl amine oxide, hexadecyl dihydroxyethyl amine oxide, cetyl dimethyl amine oxide or octadecyl amidopropyl Amine oxide, the organic acid is one or more of petroleum sulfonic acid, fatty alcohol sulfuric acid, ethylenediaminetetraacetic acid, citric acid, oxalic acid and sulfamic acid, or petroleum sulfonic acid, fatty alcohol sulfuric acid, ethyl alcohol Two of diaminetetraacetic acid, citric acid and oxalic acid, or a mixture of petroleum sulfonic acid, fatty alcohol sulfuric acid, ethylenediaminetetraacetic acid and citric acid with sulfamic acid, the alkyl low-carbon alcohol butanol or pentanol, the clay stabilizer is KCl, the pH regulator is triethanolamine, diethanolamine, ethanolamine, ammonia, NaOH, KOH, K ₂ CO ₃ or Na ₂ CO ₃ , the breaker for ammonium persulfate.

Example 9

The clean fracturing fluid of this embodiment is composed of raw gum solution, viscosity accelerator and gel breaker, and the raw gum solution is made of the following raw materials in mass percentage: 0.1% of hydrophobically associated polyacrylamide, 0.05% of organic acid , 0.1% of clay stabilizer, and the balance is water; Described viscosity accelerator is made of the raw material of following mass percent: 0.05% of octadecamidopropyl amine oxide, Gemini surfactant (carboxylate type Gemini surfactant) 0.5%, 0.1% of alkyl low-carbon alcohol, 0.05% of pH regulator, and the balance is water; the volume ratio of the original glue solution and the viscosity accelerator is 100:5, and the quality of the breaker is the quality of clean fracturing fluid 0.005%; the hydrophobic association polyacrylamide is a thickener for SXT102 fracturing (purchased from Beijing Xitao Technology Development Co., Ltd.); the organic acid is ethylenediaminetetraacetic acid, and the alkyl low-carbon alcohol is pentanol, the clay stabilizer is KCl, the pH regulator is K ₂ CO ₃ , and the breaker is ammonium persulfate.

The preparation method of the clean fracturing fluid of the present embodiment is:

Step 1. Mix SXT102 thickener for fracturing, clay stabilizer KCl, ethylenediaminetetraacetic acid and water evenly to obtain the original glue solution;

Step 2, mixing octadecamidopropylamine oxide _, Gemini surfactant, amyl alcohol and _K2CO3 evenly to obtain a viscosity accelerator;

Step 3: Mix the raw glue solution described in step 1 and the viscosity accelerator described in step 2, and then stir for 3 minutes. During construction, add a gel breaker to the stirred mixture, and mix evenly to obtain a clean fracturing fluid.

When the clean fracturing fluid in this embodiment is used, it is pumped into the oil well carrying proppant according to conventional methods.

Example 10

This example is the same as Example 9, except that the hydrophobic association polyacrylamide is FRAC-102 associate thickener (Xi'an Kali Oilfield Technology Co., Ltd.), FRA-313 associate thickener Chemical agent (Beijing Frick Technology Development Company), GRF-1 associative non-crosslinked fracturing fluid thickener (Sichuan Guangya Polymer Chemical Co., Ltd.) or CGR-7 association thickener (Chengdu Jian Xiang Shu Crown Technology Co., Ltd.), the alkyl amine oxide is octadecyl dihydroxyethyl amine oxide, hexadecyl dihydroxyethyl amine oxide, hexadecyl dimethyl amine oxide or octadecane dimethyl amine oxide, the organic acid is petroleum sulfonic acid, fatty alcohol sulfuric acid, citric acid, oxalic acid or sulfamic acid, or petroleum sulfonic acid, fatty alcohol sulfuric acid, ethylenediaminetetraacetic acid, citric acid, oxalic acid and At least two of sulfamic acid, the alkyl low-carbon alcohol is methanol or butanol, the clay stabilizer is NH ₄ Cl, and the pH regulator is triethanolamine, diethanolamine, ethanolamine, ammonia water, NaOH, KOH, Na ₂ CO ₃ or NaHCO ₃ , the breaker is chlorine dioxide.

Example 11

The clean fracturing fluid of this embodiment is composed of raw gum solution, viscosity accelerator and gel breaker, and the raw gum solution is made of the following raw materials in mass percentage: 0.5% of hydrophobically associated polyacrylamide, 0.2% of organic acid , clay stabilizer 0.8%, and the balance is water; Described viscosity accelerator is made of the raw material of following mass percent: hexadecyl dimethyl amine oxide 0.4%, Gemini surfactant (quaternary ammonium salt type Gemini surfactant agent) 0.1%, alkyl low-carbon alcohol 1.0%, pH regulator 0.4%, and the balance is water; the volume ratio of the original glue solution and the viscosity accelerator is 100:7, and the quality of the gel breaker is clean fracturing 0.01% of the liquid mass; the hydrophobic association polyacrylamide is a CGR-7 association thickener (purchased from Chengdu Jianxiang Shuguan Technology Co., Ltd); the organic acid is petroleum sulfonic acid and ethylenediaminetetra A mixture of acetic acid (the mass ratio of petroleum sulfonic acid and ethylenediaminetetraacetic acid is 1:3), the alkyl lower alcohol is butanol, the clay stabilizer is NH ₄ Cl, and the pH regulator is KOH , the breaker is ammonium persulfate.

The preparation method of the clean fracturing fluid of the present embodiment is:

Step 1. Uniformly mix CGR-7 associate thickener, clay stabilizer NH ₄ Cl, petroleum sulfonic acid, oxalic acid, sulfamic acid and water to obtain the original glue solution;

Step 2, mixing cetyl dimethyl amine oxide, Gemini surfactant, butanol and KOH evenly to obtain a viscosity accelerator;

Step 3: Mix the raw glue solution described in step 1 and the viscosity accelerator described in step 2, and then stir for 3 minutes. During construction, add a gel breaker to the stirred mixture, and mix evenly to obtain a clean fracturing fluid.

When the clean fracturing fluid in this embodiment is used, it is pumped into the oil well carrying proppant according to conventional methods.

Example 12

This example is the same as Example 11, except that the hydrophobic association polyacrylamide is FRAC-102 associate thickener (Xi'an Kali Oilfield Technology Co., Ltd.), FRA-313 associate thickener Chemical agent (Beijing Frick Technology Development Company), GRF-1 associative non-crosslinked fracturing fluid thickener (Sichuan Guangya Polymer Chemical Co., Ltd.) or SXT102 thickener for fracturing (Beijing Xitao Technology Co., Ltd.) Development Co., Ltd.), the alkyl amine oxide is octadecyl dihydroxyethyl amine oxide, hexadecyl dihydroxyethyl amine oxide, hexadecyl dimethyl amine oxide, octadecyl dimethyl amine oxide or octadecamidopropyl amine oxide, the organic acid is one or more of petroleum sulfonic acid, fatty alcohol sulfuric acid, ethylenediaminetetraacetic acid, citric acid, oxalic acid and sulfamic acid, or Two of fatty alcohol sulfuric acid, ethylenediaminetetraacetic acid, citric acid, oxalic acid and sulfamic acid, or a mixture of fatty alcohol sulfuric acid, citric acid, oxalic acid and sulfamic acid and petroleum sulfonic acid, the The alkyl lower alcohol is methanol or amyl alcohol, the clay stabilizer is KCl, the pH regulator is triethanolamine, diethanolamine, ethanolamine, ammonia, NaOH, K ₂ CO ₃ , Na ₂ CO ₃ or NaHCO ₃ , The breaker is chlorine dioxide.

Performance comparison of fracturing fluid of the present invention with VES fracturing fluid and polymer fracturing fluid:

Table 1 Performance comparison of three types of fracturing fluids

It can be seen from Table 1 that the clean fracturing fluid of the present invention is a fracturing fluid system between VES clean fracturing fluid and polymer fracturing fluid. It inherits the advantages of the two fracturing fluids, avoids their disadvantages, and has excellent performance.

The clean fracturing fluid of the present invention breaks the gel at different times, and there is almost no residue after the gel is broken. The viscosity after the gel is detected, and the results are shown in the table below.

Table 2 Viscosity test results after gel breaking at different times

It can be seen from Table 2 that when the temperature is 80-100°C and the concentration of the fracturing fluid breaker is 0.03%-0.05%, the fracturing fluid can be completely broken within 4.0 hours, and the viscosity of the solution after breaking is very low. The viscosity after breaking the gel is less than 3.2mPa·s, and the surface tension is less than 28mN/m.

Table 3 Comparison of residues between the clean fracturing fluid of the present invention and conventional guar gum fracturing fluid

Fracturing fluid Residue content ppm Phenomenon Guar Gum Fracturing Fluid 350 gel breaking fluid has floc Clean fracturing fluid of the present invention almost no residue clear and bright

It can be seen from Table 3 that the clean fracturing fluid of the present invention has almost no residue, is clear and translucent, and belongs to clean fracturing fluid.

The artificial rock core with a diameter of 3.8 cm and a length of 7.6 cm was used to carry out a dynamic damage test to compare the damage of the clean fracturing fluid of the present invention and the conventional guar gum fracturing fluid to the core. The results are shown in Table 4.

Table 4 Comparison of damage to rock core between clean fracturing fluid of the present invention and conventional guar gum fracturing fluid

It can be seen from Table 3 that the fracturing fluid of the present invention has almost no residue, is clear and translucent, and belongs to clean fracturing fluid. As can be seen from Table 4, using a diameter of 3.8cm, the dynamic damage test carried out by an artificial rock core with a length of 7.6cm shows that the clean fracturing fluid of the present invention has less damage to the permeability of the core matrix, and its average damage rate is 5.08%. Under the same conditions, the permeability damage rate of guar gum fracturing fluid reaches 28.30%. It can be seen that the clean fracturing fluid of the present invention can significantly reduce damage to rock cores.

The above are only preferred embodiments of the present invention, and do not limit the present invention in any way. All simple modifications, changes and equivalent structural changes made to the above embodiments according to the technical essence of the invention still belong to the technical solution of the present invention. within the scope of protection.

Claims (6)

1. a clean fracturing fluid, it is characterized in that, formed by original gelatin, viscosity promotor and gel breaker, described original gelatin is made up of the raw material of following mass percent: hydrophobic association polyacrylamide 0.1%～0.5%, organic acid 0.05%～0.2%, clay stabilizer 0.1%～0.8%, surplus is water; Described viscosity promotor is made up of the raw material of following mass percent: alkyl amine oxide 0.05%～0.4%, and Gemini tensio-active agent 0.1%～0.5%, alkyl low-carbon alcohol 0.1%～1.0%, pH adjusting agent 0.05%～0.4%, surplus is water; The volume ratio of described original gelatin and viscosity promotor is 100:(5～10), the quality of gel breaker is 0.005%～0.05% of clean fracturing fluid quality; Described organic acid is one or more in mahogany acid, fatty alcohol sulphuric acid, ethylenediamine tetraacetic acid (EDTA), citric acid, oxalic acid and thionamic acid, and clay stabilizer is NH ₄cl or KCl; Described alkyl low-carbon alcohol is methyl alcohol, butanols or amylalcohol, and pH adjusting agent is trolamine, diethanolamine, thanomin, NaOH, KOH, K ₂cO ₃, Na ₂cO ₃or NaHCO ₃; Described gel breaker is ammonium persulphate or dioxide peroxide.

2. a kind of clean fracturing fluid according to claim 1, it is characterized in that, described original gelatin is made up of the raw material of following mass percent: hydrophobic association polyacrylamide 0.1%～0.3%, organic acid 0.05%～0.1%, clay stabilizer 0.2%～0.6%, surplus is water; Described viscosity promotor is made up of the raw material of following mass percent: alkyl amine oxide 0.1%～0.3%, and Gemini tensio-active agent 0.2%～0.4%, alkyl low-carbon alcohol 0.3%～0.8%, pH adjusting agent 0.1%～0.3%, surplus is water; The quality of described gel breaker is 0.03%～0.05% of clean fracturing fluid quality.

3. a kind of clean fracturing fluid according to claim 2, is characterized in that, described original gelatin is made up of the raw material of following mass percent: hydrophobic association polyacrylamide 0.2%, and organic acid 0.08%, clay stabilizer 0.5%, surplus is water; Described viscosity promotor is made up of the raw material of following mass percent: alkyl amine oxide 0.15%, and Gemini tensio-active agent 0.3%, alkyl low-carbon alcohol 0.5%, pH adjusting agent 0.15%, surplus is water; The quality of described gel breaker is 0.04% of clean fracturing fluid quality.

4. according to a kind of clean fracturing fluid described in claim 1,2 or 3, it is characterized in that, described hydrophobic association polyacrylamide is FRAC-102 associated complex viscosifying agent, FRA-313 associated complex viscosifying agent, GRF-1 association type non-crosslinked fracturing fluid thickener, CGR-7 associated complex viscosifying agent or SXT102 pressure break viscosifying agent.

5. according to a kind of clean fracturing fluid described in claim 1,2 or 3, it is characterized in that, described alkyl amine oxide is octadecyl dihydroxy ethyl amine oxide, hexadecyl dihydroxy ethyl amine oxide, cetyl dimethyl amine oxide, octadecyl dimethyl amine oxide or stearylamide propyl group amine oxide.

6. a method of preparing clean fracturing fluid as described in claim 1,2 or 3, is characterized in that, the method comprises the following steps:

Step 1, hydrophobic association polyacrylamide, clay stabilizer, organic acid and water are mixed, obtain original gelatin;

Step 2, alkyl amine oxide, Gemini tensio-active agent, alkyl low-carbon alcohol and pH adjusting agent are mixed, obtain viscosity promotor;

Step 3, by viscosity promotor described in original gelatin described in step 1 and step 2 mix after stir 1min～5min, when construction to stir after mixture in add gel breaker, mix, obtain clean fracturing fluid.