download pdf version of PhD book - Universiteit Utrecht

5. Pore-Network Modeling of Two-Phase Flow
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
of one and retained only the percolating backbone of the pore space. In our
stochastic network, we also eliminated pores with the coordination number of
one, except those which were located at the inlet and outlet boundaries of the
network, since they are carrying flow and belong to the percolating backbone.
The other difference is that Lindquist et al. [2000] defined pores with coordination
number two to be part of a channel; in our stochastic network, the pores
with coordination number of two are kept as pore bodies.
Figure (5.16) shows the resulting relative permeabilities with and without considering
resistance to the flow within the pore bodies. Here again, neglecting
pore body resistance to the flow results in a significant overestimation of relative
permeability.
Figure 5.16: Comparison of relative permeability computed with and without
consideration of pore body resistance to the wetting flow.
5.4.3 The concept of equivalent pore conductance
An alternative method to the approach presented here is to modify the conductance
of pore throats to account for the resistance to the flow within the
two adjacent pore bodies [Mogensen and Stenby, 1998, Sholokhova et al., 2009,
Fenwick and Blunt, 1998, Dillard and Blunt, 2000]. This can be done through
assigning an effective conductance to a given pore throat, for example as the
harmonic mean of its own conductances and those of its two neighboring pore
bodies [Fenwick and Blunt, 1998, Dillard and Blunt, 2000]:
120