Optical Characteristics of Petroleum Crudes–Surfactant–Brine Solutions: Understanding Molecular Level Interaction for Designing Injection Fluids for Enhanced Oil Recovery

Abstract

Surfactant flooding plays a major role in the enhanced oil recovery (EOR) methods to recover the crude oil trapped in the reservoir through their interaction with the crude oil by reducing the interfacial tension of the oil–water system and altering the wettability of the reservoir system. It is therefore vital to understand the molecular interaction between crude oil with different surfactants and brines for proper designing of injection fluid. Three petroleum crudes from different fields of Cambay Basin, India, were characterized using optical spectroscopy approach. The crude oil samples were mixed with three different type surfactants—anionic (sodium dodecyl sulphate), cationic (cetyl trimethyl ammonium bromide) and non-ionic (Triton X-100) to study the interaction behaviour of surfactant–brine with crude oil. These samples were analysed using optical characterization techniques, namely dynamic light scattering (DLS) and UV–visible and fluorescence spectroscopic approach to examine the particle size distribution and entrapment of crude oil components in the micelle structure. The particle size of different surfactant–brine solutions with different crude oils is analysed. The absorption and fluorescence behaviour of crude oil samples with different surfactant–brine solutions show unique emission spectra in each case. In the present study, we have established that the intrinsic optical behaviour of crude oil can monitor its interaction with surfactant self-assemblies (micelle) of different charges and could be used for effective designing of the EOR fluids.KeywordsDynamic light scattering (DLS)Optical spectroscopyPetroleum crudesEnhanced oil recovery (EOR)MicelleCambay basin