| Through the surfactant screening tests, three kinds of surfactant system are determined by which the oil in third class oil layer could achieve super-low interfacial tension: the blends with system between amide betaine and heavy alkyl benzene sulfonic acid sodium in alkali system,anionic and nonionic salt system and non-alkali nonionic surfactant system. It researches the change rule of the interfacial activities in the three surfactant system of the conditions of surfactant concentration, alkali (NaOH) concentration, salt (NaCl) concentration, water salinity, experimental temperature. Experimental results show that three kinds of surfactant system can achieve super-low interfacial tension at a given concentration, alkali and salt all have certain effect to the interfacial tension in surfactant system, the influence of temperature to the three kinds of surfactant system is not obvious, interfacial tension stability of these three kinds of surfactant system is good. It studied emulsifying ability and adsorption retention rules of the three kinds of surfactant system. Results show that emulsified effect is obvious as the increase of surfactant concentrations; Under the condition of the same permeability, three kinds of surfactant system for the adsorption size order is that the blends with system between amide betaine and heavy alkyl benzene sulfonic acid sodium in alkali system> nonionic surfactant system> Anionic and nonionic salt system.With the three kinds of surfactants as foundation, It studied recovery influence of various potions of the surfactant system in displacement experiment. Results show that each surfactant system under the condition of the same concentration, the extent of enhancing oil recovery in 80x10-3um2 core is bigger than 40x10-3um2 core. In the same permeability core, it has a larger extent of oil recovery in larger concentration surfactant system. The displacement experiment shows that the injection pressure is stable of each surfactant system. |
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