Revisiting the Drainage Relative Permeability Measurement by Centrifuge Method Using a Forward-backward Modelling Scheme

Measurement of drainage relative permeability by the centrifuge method was first introduced by Hagoort. It has been shown that capillary end effects can cause errors in the measurements if a minimum rotational speed is not honored. To determine the min ! , we propose maintaining the value of capillary-gravity number, cg N , to be of the order of 10 -2 or smaller, at which the capillary end effect becomes negligible. The above conclusions were determined by applying a forward numerical simulator developed for centrifuge experiments and applying Hagoort’s method as a backward model. These forward and backward models form a forward-backward loop which is a powerful tool for error analysis such as determining the impact of capillary end effects. Introduction Measurement of drainage relative permeability using the centrifuge method was first introduced by Hagoort. He viewed the gravity drainage process as a gravity stable BuckleyLeverett displacement with the same set of assumptions. In addition, he assumed constant centrifugal acceleration along the core length and infinite mobility for the gas phase. In the full version of this paper, it will be shown that these assumptions are reasonable. Nevertheless, error caused by capillary end effect is one of the issues in relative permeability measurements. In the centrifuge method, if the rotational speed, ! , of the experiment PETROLEUM SOCIETY CANADIAN INSTITUTE OF MINING, METALLURGY & PETROLEUM