CN102559166B - A kind of amphoteric surfactant fracturing fluid and preparation method thereof - Google Patents

Abstract

The invention relates to an amphoteric surfactant fracturing fluid and a preparation method thereof, wherein the amphoteric surfactant fracturing fluid comprises 3-5% of amphoteric surfactant, 0.5-1% of anionic surfactant, 2-4% of inorganic salt, 0.3-0.5% of low molecular alcohol, 0-5% of pH value regulator, 0.5% of clay stabilizer and the balance of water by mass percent; firstly, adding an amphoteric surfactant, an anionic surfactant, low molecular alcohol, a pH value regulator and a clay stabilizer into water, stirring for 5-10min to obtain uniform and stable suspension, adding an inorganic salt, and stirring for 1-2min to obtain a fluid with good viscoelasticity; the amphoteric surfactant fracturing fluid is used for oil-gas field fracturing at the formation temperature of 60-80 ℃, has no residues after gel breaking, and does not damage the formation.

Description

A kind of amphoteric surfactant fracturing fluid and preparation method thereof

technical field

The invention relates to a fracturing fluid for hydraulic fracturing stimulation measures in the process of oil and gas field exploitation, in particular to an amphoteric surfactant fracturing fluid and a preparation method thereof.

Background technique

As the main stimulation measure of low permeability oil and gas reservoirs, fracturing has been developed rapidly and widely used, and fracturing fluid is an important part of fracturing technology. The most commonly used fracturing fluids at home and abroad are mainly water-based fracturing fluids with natural vegetable gum, cellulose and synthetic polymers as thickeners, which have been widely used in various oil fields and have achieved good production stimulation effects. However, the disadvantage of the water-based polymer fracturing fluid system is that the fracturing fluid does not completely break the gel, and the residue after the gel breaks will block the pores and fractures of the rock, reducing the conductivity of the fracture propped zone and the permeability of the oil and gas layer, thereby greatly reducing the fracturing effect. As a result, the stimulation effect of fracturing cannot be optimal.

Contents of the invention

The object of the present invention is to provide a fracturing fluid based on amphoteric surfactants and a preparation method thereof, wherein the amphoteric surfactant molecules contain cationic and anionic hydrophilic groups, and the attraction between anions and cations promotes the tight arrangement of surfactant molecules. Micellar gels of different strengths can be formed in salt solutions or acid solutions at different pH values, which can be used to prepare a variety of working fluids with excellent performance, without cross-linking agents, gel breakers and other chemical additives, fracturing fluids The residue content is almost zero, so there is no formation damage and the filling layer can maintain good conductivity, which can more effectively improve the productivity of oil and gas wells and fully achieve the purpose of fracturing oil and gas wells.

The amphoteric surfactant fracturing fluid of the present invention comprises 3%-5% of amphoteric surfactants, 0.5%-1% of anionic surfactants, 2%-4% of inorganic salts, and 0.3%-0.5% of low-molecular alcohols by mass percentage. %, pH adjuster 0%-5%, clay stabilizer 0.5%, and the rest is water.

The preparation method of the amphoteric surfactant fracturing fluid is divided into two steps. First, the amphoteric surfactant, anionic surfactant, low-molecular alcohol, pH regulator and clay stabilizer are added to water according to a certain mass percentage, and stirred After 5-10 minutes to obtain a uniform and stable suspension, add inorganic salts and stir for 1-2 minutes to obtain a fluid with good viscoelasticity.

The amphoteric surfactant described in the present invention is octadecyl betaine, octadecyl dimethyl betaine, oleic acid amidopropyl betaine or erucic acid amidopropyl betaine. The anionic surfactant is sodium fatty acid methyl ester sulfonate or sodium dodecyl diphenyl ether disulfonate. Described inorganic salt is sodium chloride. The low molecular weight alcohol is methanol or ethanol. The pH regulator is formic acid. Described clay stabilizer is potassium chloride.

The amphoteric surfactant fracturing fluid described in the present invention adopts amphoteric surfactant as main thickening agent, anionic surfactant as auxiliary thickening agent, inorganic salt as gel accelerator, and can thicken under different pH conditions. to form a viscoelastic fluid and obtain an amphoteric surfactant fracturing fluid. The amphoteric surfactant fracturing fluid prepared by the invention has the advantages of low viscosity, high elasticity, low friction, high sand carrying, effective control of fracture height, and increase of fracture length. No residue after glue, no damage to the formation.

The surface active agent fracturing fluid prepared by the present invention is evaluated indoors: the temperature resistance can reach above 60°C, which is superior to other clean fracturing fluid systems. Adding water (or hydrocarbons) at a ratio of 1:1 can completely break the gel, and finally The viscosity of the gel breaking fluid is less than 5mPa.S, the surface tension of the gel breaking fluid of the system is 23.59mN/m, and the interfacial tension value is 1.03mN/m, indicating that the system has good flowback performance.

Detailed ways

Example 1

Under stirring conditions, add 5g of octadecyl betaine, 1g of sodium dodecyl diphenyl ether disulfonate, 0.5g of methanol, 5g of formic acid, and 0.5% potassium chloride into 84g of distilled water, and stir for 5-10min. After obtaining a milky white stable suspension, add 4g of sodium chloride and stir for 1-2 minutes to obtain a transparent viscoelastic fluid.

The performance of the amphoteric surfactant fracturing fluid was tested by the EX2000 rheometer of TA Company in the United States. At 60 ° C, the viscosity remained at 40 mPa·s after shearing at 170 s ^-1 for 1 h.

The amphoteric surfactant fracturing fluid described in this embodiment includes 5% octadecyl betaine, 1% sodium dodecyl diphenyl ether disulfonate, 0.5% methanol, and 5% formic acid by mass percentage , sodium chloride 4%, clay stabilizer 0.5%, and the rest is water. The amphoteric surfactant fracturing fluid obtained in this example can be used for fracturing at a formation temperature of 60°C.

Example 2

Under stirring conditions, 5g of octadecyldimethyl betaine, 1g of sodium fatty acid methyl ester sulfonate, 0.5g of methanol, and 0.5g of potassium chloride were added to 89g of distilled water, and stirred for 5-10min to obtain a milky white stable suspension To the turbid liquid, add 4g of sodium chloride and stir for 1-2min to obtain a transparent viscoelastic fluid.

The performance of the amphoteric surfactant fracturing fluid was tested by the EX2000 rheometer of TA Company in the United States. At 60 ° C, the viscosity remained at about 36 mPa·s after shearing at 170 s ^-1 for 1 h.

The amphoteric surfactant fracturing fluid described in this embodiment includes 5% octadecyl dimethyl betaine, 1% sodium fatty acid methyl ester sulfonate, 0.5% methanol, and 4% sodium chloride by mass percentage , clay stabilizer 0.5%, the rest is water. The amphoteric surfactant fracturing fluid obtained in this example can be used for fracturing at a formation temperature of 60°C.

Example 3

Under stirring conditions, 3g oleic acid amidopropyl betaine, 0.5g sodium dodecyl diphenyl ether disulfonate, 0.3g ethanol, 5g formic acid, 0.5g potassium chloride were added to 84.7g distilled water respectively, and stirred for 5 -10min to obtain a milky white stable suspension, then add 4g of sodium chloride and stir for 1-2min to obtain a transparent viscoelastic fluid.

The performance of the amphoteric surfactant fracturing fluid was tested by the EX2000 rheometer of TA Company in the United States. At 60 ° C, the viscosity remained at about 55 mPa·s after shearing at 170 s ^-1 for 1 h.

The amphoteric surfactant fracturing fluid described in this embodiment comprises oleic amidopropyl betaine 5%, sodium dodecyl diphenyl ether disulfonate 0.5%, methanol 0.3%, formic acid 5% by mass percentage %, sodium chloride 4%, clay stabilizer 0.5%, and the rest is water. The amphoteric surfactant fracturing fluid obtained in this example can be used for fracturing at a formation temperature of 60°C.

Example 4

Under stirring conditions, add 5g of erucamide propyl betaine, 1g of sodium fatty acid methyl ester sulfonate, 0.3g of ethanol, and 0.5g of potassium chloride to 91.2g of distilled water, and stir for 5-10min to obtain a milky white stable suspension Liquid, then add 2g sodium chloride, stir for 1-2min to obtain a transparent viscoelastic fluid.

The performance of the amphoteric surfactant fracturing fluid was tested by the EX2000 rheometer of TA Company in the United States. At 80 ° C, the viscosity remained at about 34 mPa·s after shearing at 170 s ^-1 for 1 h.

The amphoteric surfactant fracturing fluid described in this embodiment comprises erucamide propyl betaine 5%, fatty acid methyl ester sodium sulfonate 1%, methanol 0.3%, sodium chloride 2%, clay Stabilizer 0.5%, the rest is water. The amphoteric surfactant fracturing fluid obtained in this example can be used for fracturing at a formation temperature of 60-80°C.

Claims (1)

1. an amphoterics fracturing liquid, it is characterized in that: under agitation condition, 3g amine hydroxybenzene CAB, 0.5g disodium 4-dodecyl-2,4 '-oxydibenzenesulfonate, 0.3g ethanol, 5g formic acid, 0.5g Repone K are joined respectively to 84.7g distilled water, stir 5-10min, obtain the suspension liquid that oyster white is stable, add again 4g sodium-chlor, stir 1-2min and obtain transparent viscoelastic fluid;

By this amphoterics fracturing liquid performance of the U.S. EX2000 of TA company rheometer test, at 60 ℃, with 170s ^-1after shearing 1h, viscosity still remains on 55mPas.