Oil recovery performance of surfactant solutions and adsorption in sandstone

In this article, five nonionic surfactants with different ethoxylation degrees (R70, R95, R120, R150, and R200) were evaluated in surfactant adsorption experiments and oil recovery tests. Both sets of tests were carried out in a surfactant flooding apparatus using 30 psi as pressure gradient. The concentration of the solutions injected in adsorption tests were 30% above the critical micelle concentration (c.m.c.) to ensure micelle formation. In oil recovery tests, the solution concentration varied from the c.m.c. until 500% above it. The results obtained showed that adsorption was higher for R120 and the better oil recovery was for R200.