This study is a basic resarch which has been conducted to investigate the effect of oil recovery by nonionic surfactant flooding under the low concentration of the same. For the purpose, two kinds of surfactant were selected as samples. One of them was polyethylene glycol-polypropylene glycol ether and the other was polyethylene glycol-nonylphenol ether.
In the first type, polyethylene glycol-polypropylene glycol ether, we prepare chemicals, which have various mole numbers of ethylene oxide and molecular weight of polypropylene. Concerning their low concentration, the interfacial tension between crude oil and oil recovery efficiency were measured at every temperature.
From these results, we recongnized extremely low interfacial tensions and higher recovery of residual oil when molecular weight of polypropylene glycols were 3, 000 to 4, 000 and ethylene oxide contents were 30 to 40 percent at 30°C to 40°C of test temperature.
In the second type, nonylphenol ether, the lowest interfacial tensions were obtained at 9 to 10 polymerized degrees of ethylene oxide in these surfactants, but the most recoverable efficiency was shown at 7 to 9 polymerized degrees. We could not get the clear relationship between interfacial tension and recovery efficiency in this type of surfactant.
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