| After more than 30 years of development and adjustment governance, Pucheng oilfield of Central Plains has now entered the late stage of high water cut development. It is essential to have a try of tertiary oil recovery. Microemulsion flooding is the most efficient method of chemical flooding. Micro-emulsion、the oil and water have ultra-low interfacial tension and high solubilizing capacity, so there is no capillary resistance and washing efficiency is very good. It is mainly fitted for the sandstone reservoirs with good water flooding effects.In this paper, the phase behaviors of microemulsion were studied. Microemulsion is formed spontaneously from surfactant, co-surfactants, Pucheng crude oil and oilfield injection water. The surfactant is resistant to high temperature and salt resistance, besides, its oil/water interfacial tension with crude oil reach 10-3mN/m. The better formula concentration range of microemulsion has been researched by orthogonal experiment. We analyzed the influence of co-surfactants, surfactants and salt concentration on the phase behavior of microemulsion. Some characteristic parameters of Pucheng crude oil microemulsion such as the better formula, salt wide, optimal salt concentration has been obtained. The theoretical preparation for the oil field to carry out the microemulsion and surfactants recombination displacement has been accomplished.After refining the surfactants screened out and microemulsion formulation, combining with the previous experience in the construction field, the microemulsion flooding advanced test has been carried on in the west Pucheng oilfield. Microemulsion slug injection after 2 months, production well that is seeing significant results and the test area oil production has increased significantly. |
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