Abstract
Surfactant injection can be used as an EOR technique by either altering the wettability of reservoir and/or reducing IFT of water and oil. How to balance the functionality of wettability alteration and IFT reduction of a surfactant flooding process for oil wet carbonate reservoirs is still paradox for surfactant technology selection. In this study, the effects of IFT reduction and wettability alteration by surfactant on EOR for a carbonate reservoir were studied by using two kind surfactant systems individually. For IFT reduction surfactant, the surfactants which can reach IFT at different level and ultralow IFT were synthesized based on molecular design method by only changing the structure of surfactant and without any formulation process. Moreover, these surfactants are also has a little effect on wettability alteration proven by contact angle test. The surfactants for wettability alteration study are selected based on contact angle method and also on the principle of "less effect on IFT property". The static and dynamic imbibition tests are carried out to understand the contribution of wettability alteration and IFT reduction mechanism individually to enhance oil recovery, hence, the surfactant flooding technique for an oil wet carbonate reservoir could be optimized.
