PROPAGATION OF AN ANIONIC SURFACTANT IN RADIAL SANDSTONE CORES

An experimental study was conducted to examine the propagation with ad sorption of an anionic surfactant in unfired Berea sandstone cores. Th e effects of sodium chloride concentration, pH, flow rate, surfactant concentration, and the presence of a liquid crystal phase on the rate of surfactant propagation were studied. To simulate the flow field aro und an injection well, a radial geometry was employed. Experimental re sults showed dramatic surfactant loss and slower rate of surfactant pr opagation as sodium chloride concentration was increased. On the other hand, increasing the pH of the surfactant slug from 6 to 12 reduced s urfactant loss by nearly 30 percent. At a given sodium chloride concen tration and surfactant concentration, surfactant loss was found to dec rease as the injection flow rate was increased. At high surfactant con centrations and over a narrow range ot' sodium chloride concentrations , a liquid crystal phase formed. The presence of this phase resulted i n a higher apparent viscosity, a dramatic increase in the pressure dro p across the core, and significant surfactant retention in the core. T he latter was due to the formation of viscous fingers at the tail of t he surfactant slug.