Relative Permeability

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Brief

Relative Permeability is the ratio of the effective permeability to base oil permeability measured at connate water saturation[1].

 k_{ro} = k_o/k_{oS_{wc}}
 k_{rw} = k_w/k_{oS_{wc}}

where

 k_{ro} = Oil relative permeability, fraction
 k_{rw} = Water relative permeability, fraction
 k_o = Effective water permeability, mD
 k_w = Effective water permeability, mD
 k_{oS_{wc}} = Effective oil permeability at irreducible oil saturation, mD
 S_{wc} = Connate water saturation, fraction

Related definitions

Effective permeability - oil, water, gas phase permeability when more than one phase is present. Depends on fluids saturations.

Absolute permeability - permeability of the core sample when saturated with one liquid. Independent of fluid. Dependent on pore throat sizes.

Example

Determine the Relative Permeability using the following data[1]:
Core dimensions: A=2 cm2, L=3 cm. PVT: water viscosity = 1 cP, oil viscosity = 3 cP, Bw=1 cm3/cm3, Bo=1.2 cm3/cm3.

Core is at 100% water and qw=0.553 cc/sec

Using the Darcy's law:

 k_{abs} = \frac{0.553*1*1*3}{2*2} = 0.415 D = 415 mD

In this case the mobility of water is 15 times higher than the mobility of water.

See Also

References

  1. 1.0 1.1 Wolcott, Don (2009). Applied Waterflood Field DevelopmentPaid subscription required. Houston: Energy Tribune Publishing Inc.