Several research groups have shown that injection of low saline water may result in a wettability alteration towards a more water-wet behaviour. The present work shows a core flooding series where the response to low saline water injection was interpreted as yielding more oil-wetting conditions. Interpretation of secondary injection of both highsalinity and low-salinity water indicated a more oil-wet behaviour at low salinity. Using the relative permeability and capillary pressure data derived from these experiments, predictions of a tertiary mode low salinity injection experiment were in good qualitative agreement with experimental data. An ion exchange framework has been used to explain why such a wettability alteration is plausible for the present system. The ion exchange mechanism has been reviewed to show how it can explain wettability alteration in both directions; either more oil-wetting or more water-wetting, depending on the oil and rock properties. A pH increase acts in the opposite direction than a decreased salinity. The latter may lead to artefacts in low pressure core floods and a simple CO2 buffer system has been proposed as a convenient method to eliminate this pH uncertainty.
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