A Supercritical CO2 Microemulsion Formed from Anion-Non-Zwitterionic Surfactants

Abstract

The invention discloses a supercritical CO2 microemulsion formed by an anionic-nonionic amphoteric surfactant. 100 parts by weight of the supercritical CO2 microemulsion are prepared from the following components: 0.1-20 parts of water, 1*10<-4>-1*10<-1> parts of the surfactant, 1-10 parts of a cosolvent and the balance of CO2. The preparation method of the supercritical CO2 microemulsion comprises steps as follows: (1) the cosolvent in certain mass is mixed with water at the temperature of 20-25 DEG C and stirred uniformly; (2) the anionic-nonionic amphoteric surfactant in certain mass is weighed and added to a mixed solution of the water and the cosolvent and stirred to be dissolved; (3) the mixed solution is added to a transparent high-pressure container, CO2 is introduced, the mixture is stirred and completely miscible, and the supercritical CO2 microemulsion is formed. The anionic-nonionic amphoteric surfactant does not have a cloud point and has good solubility, good hydrophilia and a wide application range; ion components are simple, and the interface stability is high; polar heads are distributed more uniformly in a concentrated manner through the single-stranded surfactant, and the hydrophilia is higher; the surfactant has high solulbilizing power and is low in cost and suitable for large-scale application in an oil field.

Description

technical field [0001] The invention relates to the technical field of oil exploitation and oilfield chemistry, in particular to a supercritical CO formed by an anion-non-zwitterionic surfactant. 2 Microemulsion. Background technique [0002] Supercritical CO 2 Microemulsion systems have been widely used in the fields of extraction, organic synthesis, nanomaterial preparation and cleaning, and have shown excellent performance. In terms of tertiary oil recovery, CO 2 Oil displacement technology can effectively develop low permeability and heavy oil reservoirs. With the deepening of research, CO 2 There are more and more applications in oilfield exploitation, and field tests have been started in Jiangsu, Zhongyuan, Daqing, Shengli and other oilfields in China. In foreign countries, since the 1980s, CO 2 Oil displacement technology has been successfully applied in low-permeability reservoirs in the United States, the former Soviet Union, Canada, and Algeria, and this tech...

AI Technical Summary

Problems solved by technology

This type of surfactant exhibits a strong affinity for CO 2 properties, but a notable feature of nonionic surfactants is the presence of cloud point, when the temperature is higher than the cloud point, its hydrophilicity becomes poor, easy to precipitate and make the system turbid

However, the formation temperature is generally high, which limits the application of such surfactants in the oil field

If the anionic surfactant is simply compounded with a nonionic surfactant, too many impurity ions will be added to the system, which will affect the charge distribution of the interface layer of the microemulsion, thereby reducing the stability of the microemulsion

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