Viscoelastic Surfactant System and Its Application in Waterflooding Heavy Oil Reservoir Production

Abstract

The invention discloses a viscoelastic surfactant system, which is composed of a cationic oligomeric surfactant, an anionic nonionic surfactant, a small molecule additive and water, and the cationic oligomeric surfactant accounts for 0.01% to 1%. Anionic and nonionic surfactants account for 0.05% to 3%, and small molecule additives account for 0.02% to 5%. The anionic nonionic surfactant is selected from alkylphenol polyoxyethylene ether sulfonate and alkyl alcohol polyoxyethylene ether sulfonate. The application of the viscoelastic surfactant system of the present invention in the production of water flooding heavy oil reservoirs. The viscoelastic surfactant system of the present invention has dual functions of regulating and driving and reducing viscosity, can effectively reduce the viscosity of heavy oil, and greatly reduce the viscous force of heavy oil in rock voids; at the same time, it can also increase the viscosity of the water phase, Reducing the mobility ratio and increasing the swept volume can effectively improve the efficiency of water flooding; it can also reduce the oil-water interfacial tension to an ultra-low range, thereby effectively improving the recovery of heavy oil in water flooding.

Description

technical field

[0001] The invention relates to a viscoelastic surfactant system, in particular to a viscoelastic surfactant system containing a specific oligomeric cationic quaternary ammonium salt surfactant, and the use of the viscoelastic surfactant system in water flooding heavy oil reservoirs The application in mining technology belongs to the field of oil mining technology. Background technique

[0002] In the development process of heavy oil reservoirs, for the heavy oil reservoirs whose underground crude oil viscosity is higher than 2000mPa·s, they can be effectively developed by means of steam thermal recovery. However, for heavy oil reservoirs with underground crude oil viscosity values ​​between 150 and 2000 mPa·s, due to their better underground fluidity, the water flooding heavy oil method is usually preferred for development. Compared with steam thermal recovery technology, the cost of water flooding heavy oil is lower and the economic benefit is better, so t...

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