High-efficiency emulsification anionic surfactant for enhancing heavy oil recovery

Abstract

A high-efficiency anionic surfactant alcohol ethoxylate sodium hydroxypropyl sulfonate (AEOSHS) suitable for enhancing heavy oil recovery has been synthesized through chemical modification. Its structure and properties were characterized by FT-IR, TGA and SFT. Then, the performance of surfactant AEOSHS was better than traditional anionic surfactant sodium dodecyl sulfate (SDS) confirmed through emulsification state observation, droplet size distribution test, interfacial tension (IFT) test, rheological test and porous level emulsification visualization observation. The mechanism of surfactant AEOSHS to efficiently emulsify heavy oil and W/O emulsion was clarified. Finally, the enhancing heavy oil recovery of surfactant SDS and AEOSHS was compared through long sand-packed tube flooding experiment. Experimental results show that when surfactant concentration was 0.5%, the IFT between surfactant SDS solution and dehydrated heavy oil was 0.34 mN/m, while the IFT of AEOSHS was only 0.092 mN/m. As water content of W/O emulsion increase, its density, viscosity and IFT were all increase. Surfactant AEOSHS molecule can dissolved in heavy oil because the long carbon chain and the existence of ether bonds. It can effectively disperse the layer stacking structure of resin and asphaltene so that water in W/O emulsion can be effectively emulsified. In addition, surfactant AEOSHS can emulsify heavy oil into small droplets (7.1 µm), which has high elastic modulus, so that the additional resistance was very small when it flows through porous media. Through flooding experiments, which shown that surfactant AEOSHS (0.5PV) can enhancing heavy oil recovery rate up to 18.17%, while SDS was only 8.71%. Therefore, the newly synthesized anionic surfactant AEOSHS has the ability to significantly reduce IFT and high-efficiency emulsification, and can be used for enhancing heavy oil recovery.