Kansas Geological Survey
Open-file Report 2003-31

Modeling Relative Permeability

Since relative permeability end point saturations change with permeability (e.g., “irreducible” water saturation changes with permeability), the relative permeability curves also change with absolute permeability. Relative permeability curves for any given permeability were modeled using Corey-type equations where Swi was obtained from Pc-k relations and the average absolute permeability values assigned. Exponent m and n values were initially obtained from measured data and were modified during simulation to reproduce lease production data.

kro = 1(1-SwD)m
krw = 2 wDn
SwD = (Sw-Swi)/(1-Swi-Sorw)

For moldic-porosity Mississippian rocks residual oil saturation to waterflood also changes with permeability and/or Swi following the general trend: Sorw=(1-(Swi+0.5)). Initial pseudo-Swi values were assigned to each layer using Pc-k relations discussed.

Wellington West dolomites exhibit a general increase in pore body size with increasing k as shown by Nuclear Magnetic Resonance T2 times.

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Last updated July 2003