Application of Natural Source Surfactants in Development of Ultra Low Permeability Reservoirs
Due to the fact that most of the domestic oil fields have entered the late stage of development,the development of ultra-low permeability oil reservoirs has become the main research direction under the background that traps with good porosity and permeability have been drilled out.In development practice,a new type of surfactant was prepared using saponins as raw materials.This surfactant is a natural source and has good application value in ultra-low permeability reservoirs represented by carbonate rocks through experiments such as interfacial tension,contact angle,and oil recovery evaluation.The ability of surfactant to generate foam and establish stable emulsion on micro and macro scales was evaluated.The research results indicated that when the mass concentration of surfactants reached 1800 mg·L-1,the interfacial tension significantly decreased,reaching the minimum of 0.39 mN·m-1.In addition,by optimizing salinity,the interfacial tension was reduced to the minimum of 0.36 mN·m-1,indicating the role of salinity control in reducing interfacial tension.The experimental results showed that the new surfactant from natural sources showed excellent lotion stability at its critical micelle concentration,and its properties did not change significantly after 6 months.The foam produced by this new surfactant also showed remarkable stability,with a half-life of up to 30 min.Therefore,it can be concluded that in the oil displacement experiment conducted under optimal conditions,when the new surfactant solution is at its critical micelle concentration,and the salinity and alkalinity levels are optimized,the oil recovery rate of crude oil can be significantly improved by 25%,which has better chemical properties than traditional surfactants and will bring significant gains for the development of ultra-low permeability reservoirs in the future.
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