The Amott test is one of the most widely used empirical wettability measurements for reservoir cores in petroleum engineering.
This test defines two different indices: the Amott water index (
It is a number between −1 and 1 describing wettability of a rock in drainage processes.
It is defined as: These two indices are obtained from special core analysis (SCAL) experiments (porous plate or centrifuge) by plotting the capillary pressure curve as a function of the water saturation as shown on figure 1: with
is the water saturation for a zero capillary pressure during the imbibition process,
is the oil saturation for a zero capillary pressure during the secondary drainage process,