Water flooding of oil reservoirs, with a purpose of providing pressure support in the reservoir and displacing the oil by using viscose forces, has for a long time been considered as a secondary oil recovery method. The water used at the moment for flooding is not efficient in carbonates as in sandstones. However, more than 50% of proven oil reserves account for carbonate reservoirs. In the recent years, extensive researches have revealed how important it is to take into consideration the characteristics of wettability of the pore spaces for a successful oil displacement. Initial reservoir wettability, which was established for millions of years, can be non-optimal for oil displacement. By injecting a “Smart Water” i.e. seawater with optimal ionic composition and salinity, it is possible to change the wettability in carbonates, hence, significantly improve recovery in carbonate reservoirs (Austad, 2012).
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