Gr. Jerauld et Jj. Rathmell, WETTABILITY AND RELATIVE PERMEABILITY OF PRUDHOE BAY - A CASE-STUDY IN MIXED-WET RESERVOIRS, SPE reservoir engineering, 12(1), 1997, pp. 58-65
This paper describes the variation in wettability and relative permeab
ility at Prudhoe Bay. We show that measurements are consistent with re
cent theories of the relationship between water-saturation, pH, wettab
ility and relative permeability.(1) In particular, the wettability of
the reservoir changes from water-wet low on structure near the water/o
il contact to mixed-wet behavior higher on structure. Increasing oil/w
etting character is correlated to decreasing water saturation. Changes
in wettability are also accompanied by changes in water-flood recover
y efficiency and are optimum at Amott indices approaching zero. Lithol
ogy also impacts recovery efficiency, with more clay-rich rocks having
higher residual oil saturations.