This paper investigates the effect of low salinity water injection (LSWI) on both oil displacement and volumetric sweep efficiencies. A new definition of mobility ratio is proposed and shown to correlate with volumetric sweep efficiency better than other definitions in the literature. A quarter 5-spot field model was created by upscaling recently published coreflood experiments. Simulations were performed using the Empirical LSWI Model implemented in the UTCHEM simulator. Results showed an improved estimation of volumetric sweep efficiency with the proposed mobility ratio definition, which applies in the tertiary mode and physically makes more sense compared to other definitions in the literature. (C) 2015 Elsevier Ltd. All rights reserved.