Gas and condensate relative permeability at near-critical conditions: capillary and Reynolds number dependence

Measurement of gas and condensate relative permeabilities is typically performed through steady state linear coreflood experiments. Experiments are normally designed to minimize the saturation variations throughout the core so that the relative permeabilities can be evaluated through direct application of Darcy's Law to each phase. This study addresses relative permeability prediction from linear corefloods for low permeability, near-critical gas-condensate systems at velocities typical of the near wellbore region. In this regime, relative permeabilities are capillary number dependent and non-Darcy terms are significant. This paper looks at combining both the nonlinear (in velocity) terms into a single "effective relative permeability" term. Synthetic "experimental" data were generated numerically through simulation (and not from laboratory experiments). The synthetic data considered a range of capillary numbers at both low and high Reynolds numbers. Simplified correlations were developed to represent both the gas and condensate effective relative permeabilities. Effective relative permeabilities were then history-matched from the synthetic experimental data through non-linear regression. History matching results indicate that the Reynolds number should be included explicitly in the gas effective relative permeability correlation. Two-phase injection experiments are easier to interpret than single-phase injection experiments. (C) 2002 Elsevier Science B.V. All rights reserved.