surfactant type and characteristics

Because EOR use of surfactants reduce interfacial tension, can increase
 Oil processing to 80% to 90%, so this is a both feasible and promising approach. EOR is currently used in the study of surfactant to anionic species, followed by non-ionic and zwitterionic, cationic applications is minimal, the following were discussed in their application and its characteristics. 2. 1 EOR types of surfactant used and the characteristics of 2.1.1 EOR anionic surfactant of anionic surfactant, the molecular structure of the ionic hydrophilic group is an anion, such anionic hydrophilic group consisting of salts are sulfonate? carboxylate? sulfate (ester) salts? phosphoric acid (ester) salts. Anionic surfactants can be used in various surface-active drive, in which the application sulfonate most, while the sulfonate anionic surfactant, the most common petroleum sulfonate. This is because it's a high cloud point, the less adsorbed on the surface of sandstone, machine for pellets, surface-active high temperature performance is good, but the salt is poor, critical micelle concentration (cmc), in the formation of adsorption? stagnation and the role of multivalent ions, resulting in a loss in the oil recovery. 2.1.2 Non-ionic surfactant is a nonionic hydrophilic group which groups, a common ether bond? Ester bond? Amide bond or a hydroxyl group, such groups or the type and amount of length, and two hydrophilic groups The carbon chain can be different between. Since the non-ionic hydrophilic group than the ionic groups much worse, so non-ionic surfactant emulsion to maintain a strong, its molecular structure contains a plurality of generally non-ionic hydrophilic group, forming an ether bond-containing many? ester bond? amide bond or a hydroxyl group, or their mutual combinations structures. Common varieties are alcohol ethoxylates series? Alkylphenol ethoxylates? Alkylphenol polyoxyethylene ether formaldehyde condensate? Polyoxyethylene polyoxypropylene block copolymers? Alkyl amide type? Polyoxyethylene polyoxypropylene ether, sulfoxide? alkyl (poly) glycoside? polyoxyethylene oleic acid ester and the like. The advantage of such surfactants are strong salt? Multivalent cation-resistant performance, cmc low, but poor stability in the formation, adsorption amount of anionic surfactant is high, but not high temperature, high price. 2.1.3 amphoteric surfactants such surfactants are anionic hydrophilic group in the molecule both cationic hydrophilic group and presents another sexes, commonly used betaine type amphoteric surfactants. As the types of surfactants chelation of metal ions, and thus can be used for most of the high salinity? Higher temperature reservoir flooding, and can greatly reduce the non-ionic surfactant and an anionic compound the chromatographic separation effect, but also has the disadvantage of high prices.