Correlations used to predict three phase relative permeability from two phase data often assume gas relative permeability is a function of gas saturation and not dependent on the liquid phase displaced. To test the validity of this assumption and to investigate the applicability of ambient condition gas/liquid relative permeability data, unsteady state displacements were conducted at ambient and reservoir conditions. All tests were performed on a composite constructed from four reservoir sandstone core plugs with similar lithological and petrophysical properties.

In-situ saturation monitoring, used throughout the ambient condition experiments, provided distributed saturation histories along the length of the composite. Good agreement between experimental observations and numerical predictions of pressure, effluent production and saturation histories indicates history matching via coreflood simulation is a valid method to obtain drainage gas/liquid relative permeability data free of sample scale capillary pressure end effects. Also, increased confidence may be placed in the results of history matching the reservoir condition displacements where distributed saturation data are not available.

History matched relative permeability data from ambient and reservoir condition tests show gas/water relative permeability data are suppressed compared to gas/oil data over a similar liquid saturation range. The good agreement between history matched ambient and reservoir condition gas/liquid data suggests ambient condition unsteady state displacements provide similar drainage relative permeability data when interpreted using coreflood simulation incorporating capillary pressure and the appropriate boundary conditions.

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