Gas-Oil Relative Permeability and Residual Oil Saturation as Related to Displacement Instability and Dimensionless Numbers

Displacement experiments of the gas-oil system are performed on long core scale models by varying the petrophysical properties and flowing conditions. Experiments are conducted in situations where capillary, gravity and viscous forces are comparable. From oil production history and picture analysis, the threshold for the stability is determined. The experimental findings are comparable to the results of a gradient percolation theory. The effect of destabilized front velocity on relative permeability and residual saturation is investigated. The relative permeabilities determined by using analytical and numerical approaches indicate that higher displacement velocity leads to a higher gas relative permeability and lower oil relative permeability. The remaining oil saturation is found to be much higher for displacement velocity above the stabilized criterion. Displacement morphology including the average remaining oil saturation is then described using dimensionless groups expressed as Bond and capillary number. Experimentally determined remaining oil saturation shows a direct and inverse relation to the capillary and Bond number respectively. Hence, a combined dimensionless group has been proposed to generalize the estimation of remaining and residual oil saturations under the range of dimensionless numbers studied here.