The standard methods for determination of the wettability of reservoir cores (Amott and USBM) involve displacement of water- or oil, in presence of both the wetting and non-wetting phases.The result may depend on fluid saturations as well as on experimental procedure, causing uncertainties of the measured wettability.

The paper presents an attempt to determine the wettability of the core material independent of the fluid saturations.The method involves contacting the core with a reagent that selectively adsorbs either to the oil-wet- or to the water wet sites of the pore wall.Adsorption tests with several compounds have led to the selection of n-heptanol and methylene-blue as agents for wettability measurements by dynamic adsorption.

The area of oil-wet sites measured by n-heptanol adsorption from brine, is found to increase for silanized cores.Correspondingly, the fractional water-wet area of the core measured by methylene blue adsorption is reduced for silane-treated Berea cores compared to untreated cores.Wettability measurements are also performed on various cores from North Sea oil reservoirs.

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