Modeling and experiments of drainage relative permeability and capillary pressure functions using a centrifuge

Centrifuge method is often used for measurement of the drainage saturation functions. The output data of the centrifuge setup is based on average saturation of core samples. Some backward methods are needed to interpret these data to saturation functions.; In this study, it was confirmed that the parameter estimation methods can be used as suitable backward methods for processing centrifuge capillary pressure raw data. For relative permeability measurement, Hagoort's method can be used successfully as an appropriate backward method provided that a minimum value for rotational speed, o, is honoured. To determine the o min, we propose using the value of capillary-gravity number, Ncg, to be of the order of 10-2 or smaller at which the capillary end effect becomes negligible. If o is smaller than omin, the calculated relative permeability should be corrected. The above conclusions were made by developing a forward numerical simulator for centrifuge experiments which forms a forward-backward loop with the backward methods.; We also propose a method for calculating capillary equilibrium time. If the value of the derivative of the pore volume produced versus time (sec) is less than 2x10-7, it can be said that a practically acceptable capillary equilibrium is reached for the cases studied.