We present a dynamic pore-scale network model of imbibition, capable of calculating residual oil saturation for any given capillary number, viscosity ratio, contact angle, and aspect ratio. Our goal is not to predict the outcome of core floods, but rather to perform a sensitivity analysis of the above-mentioned parameters, except from the viscosity ratio. We find that contact angle, aspect ratio, and capillary number all have a significant influence on the competition between piston-lice advance, leading to high recovery, and snap-off, causing oil entrapment. Due to significant CPU-time requirements we did not incorporate long-range correlations among pore and throat sizes in our network, but were limited to small-range correlations. Consequently, the gradual suppression of snap-off occurs within one order of magnitude of the capillary number. At capillary numbers around 10(-8)-10(-7), snap-off has been entirely inhibited, in agreement with results obtained by Blunt (1997) who used a quasi-static model. For higher aspect ratios, the effect of rate and contact angle is more pronounced.
|Journal||Transport in Porous Media|
|Publication status||Published - 1998|
|Event||18th IEA Workshop and Symposium on Enhanced Oil Recovery - Copenhagen, Denmark|
Duration: 1 Sep 1997 → 3 Sep 1997
|Workshop||18th IEA Workshop and Symposium on Enhanced Oil Recovery|
|Period||01/09/1997 → 03/09/1997|