화학공학소재연구정보센터
Fuel, Vol.229, 167-179, 2018
Synergism, phase behaviour and characterization of ionic liquid-nonionic surfactant mixture in high salinity environment of oil reservoirs
A large number of matured oil reservoirs still have ample quantity of oil trapped in the pores of the reservoir rock. The quest of a reliable tertiary oil recovery process has opened opportunities for chemical enhanced oil recovery processes. Most of the conventional chemicals used in this method lose their efficacy under high salinity conditions of oil reservoirs. In the present work, synergism in reducing interfacial tension between crude oil and aqueous phase has been investigated, between a mixture of long chain imidazolium ionic liquid and a nonionic surfactant. The reservoir fluid has been modelled as a system containing crude oil/kerosene and surfactant brine. Phase behaviour studies of this system at varying salinities have been studied. Formation of a distinct and stable TYPE III microemulsion at ultra-high salinities has been observed. Presence of middle phase microemulsion at very high salinities indicated ultralow interfacial tensions thereby making the mixed surfactant formulation suitable enough to be used in reservoirs having high salinity of formation brine. Characterization of this middle phase microemulsion was carried out using Transmission Electron Microscopy (TEM), Atomic Force Microscopy (AFM), Polarised optical microscopy (POM) and Dynamic light scattering (DLS) techniques. Time required for the modelled reservoir fluid to coalesce into a stable middle phase microemulsion was characterised using Turbiscan. Subsequently, flooding experiments with only ionic liquid (C(16)mimBr) and mixed system containing ionic liquid (C(16)mimBr) + nonionic surfactant (Tergitol 15-S-9) at high salinity conditions were performed. The results showed that during surfactant