The research results have shown that the mixed system can produce ultra low interfacial tensions(10 -3 mN/m order) with Daqing crude oil within a wider range of surfactant and methanol concentration, not adding any alkali to the system, but depending on synergism of methanol; it can produce ultra low interfacial tensions with Daqing crude oil after it is dilut.

Mechanism of betaine surfactant solution on residual oil after water flooding in ultralow interfacial tension;

Displacement mode of ultralow interfacial tension system in heterogeneous low permeability oil layers

The results show that an excellent surfactant AOS for displacing oil can be obtained, which can lead to an ultralow interfacial tension of 6×10~ -3 mN/m with the oil of Daqing .

A high efficiency,ultra-low interfacial tension foaming system without alkali was developed for improving the oil recovery by studying foaming property and surface tension of different surfactants,after combination this system possessed several merits,such as :high ability of anti-aging and high temperature resistance.

There are limitations in the application of classic capillary number theory to the ultra-low interfacial intension displacement system in low-permeability reservoirs,and therefore the modified formula of the capillary number is presented.

Study on ultralow interfacial tension chemical flooding in low permeability reservoirs;