Imbibition enhancing oil recovery mechanism of the two surfactants

Abstract

The subject of the imbibition enhancing oil recovery (IEOR) mechanism by the use of ultra-low interfacial tension (IFT) and emulsifying surfactants remains controversial. In this study, an ultra-low IFT surfactant (SOL) and an easy-emulsifying surfactant (SDBS) were selected on the basis of their interfacial tension and emulsion stability to elucidate the IEOR mechanism. The cell test method was used to measure the imbibition oil recovery. The micro-IEOR mechanisms were analyzed by using a new device making use of a visual micromodel. The results show that the imbibition oil recovery was 8% with SDBS and 17% with SOL, with the two surfactants having a similar variation of imbibition speed, while the ultra-low IFT made the water front more uniform. The emulsion with low coalescence stability formed by SDBS improves the displacement efficiency and diverts flow, improving the sweep efficiency as well. This work proposes a new method for analyzing the micro-IEOR mechanism and provides new fundamental information to the selection of an efficient IEOR surfactant.