In all tests, the

absolute permeability is a diagonal tensor and the porous media are isotropic.

To investigate the effective stress effect, we consider the intrinsic permeability as

absolute permeability instead which is an effective strain-based model.

where [t.sub.DMK] is the dimensionless time (s), [alpha] a units conversion factor (3.16>[10.sup.-4]), k is the

absolute permeability (md), [sigma] is the interfacial tension (mN/m), and L is the characteristic length of the sample (cm).

Absolute permeability of brine was measured on each sample in both horizontal and vertical flow orientations.

where [k.sub.0] is the

absolute permeability of the porous medium, [k.sub.ri] is the relative permeability of phase i, [[micro].sub.i] is the viscosity of phase i, and P represents phase pressure which are the same for different phases here.

Deutsch, "Calculating Effective

Absolute Permeability in Sandstone/Shale Sequences," SPE Formation Evaluation, vol.

The flow in these systems can easily be studied using, for example, the Hagen-Poiseuille approximation (for single-phase flows), which can then be used to estimate the

absolute permeability of the rock sample.

Bijeljic, "Computations of

absolute permeability on micro-CT image," Mathematical Geosciences, vol.

The relative permeability refers to the ratio between the effective permeability of each fluid type and the

absolute permeability of the rock itself, in the cases of saturated multiphase fluid in the rock pores.

Then the

absolute permeability is calculated in the following term [43]:

Figure 6 shows the cross-sectional views of the initial hydrate saturation, porosity, and

absolute permeability in the model.

where [k.sub.n] is the

absolute permeability of grid n, as specified in data block ROCKS and [[zeta].sub.n] is the permeability modification coefficient which can be defined internally or externally and maybe provided as part of the geometry data in block ELEME and then employed to multiply the

absolute permeability [k.sub.n] for each grid in the subdomain.