New insights into the interactions between asphaltene and a low surface energy anionic surfactant under low and high brine salinity

Hypothesis: The hyperbranched chains on the tail of low surface energy surfactants (LSES) causes lowering of surface free energy and rock wettability alteration, offering significant improvement in oil recovery in asphaltene oil reservoirs. Experiments: Oil sweep efficiency was determined by fluid displacement in pure brine and LSES-brine solutions in a microfluidic pattern that was representative of a sandstone cross-section. Interfacial tension (IFT), wettability alteration, Raman and X-ray photoelectron spectroscopy (XPS) were used to measure the changes of asphaltene interactions with oil-aged substrate after surface treating with brine and surfactant-brine solutions. Findings: The hyperbranched LSES yielded a significant increase in the original-oil-in-place (OOIP) recovery (58%) relative to brine flooding (25%), even in the presence of asphaltene. Raman spectra showed the LSES-brine solutions to be capable of causing change to the asphaltene aggregate size after centrifugation treatment. (C) 2020 Elsevier Inc. All rights reserved.