Pore scale visualization of low salinity water flooding as an enhanced oil recovery method

Abstract

The controlling mechanisms behind low salinity water flooding (LSWF) as an Enhanced Oil Recovery (EOR) method are not well understood. So far, a limited number of researchers have tried to provide visual and direct evidence of the underlying mechanisms behind the LS effect. In this paper, to investigate the dynamics of displacement throughout LSWF, clean and clay-coated two-dimensional glass micromodels were used, with the wettability status set at both water-wet and oil-wet conditions. Hence, pore-scale displacement mechanisms in the presence and absence of clay, as well as in the drainage and imbibition-dominated two-phase flow, were studied. In water-wet systems, in the absence and presence of clays, LSW hindered “snap-off” perhaps due to the development of a viscoelastic water−oil interface. The wettability alteration toward more water wetness was observed for oil-wet systems. The observations are discussed in terms of the expansion of the Electrical Double Layer (EDL). Fines migration played an insignificant role in our observations.