structural geology, propagation mechanics and - Stanford School of ...

5. Simulations
Three sets of 2-D simulations were performed. The first set prescribes single-phase,
incompressible well-to-well flow for a series of well pairs to examine how the band
pattern affects the pressure drop required to maintain a given flow rate. The second set of
simulations prescribes two-phase, incompressible flow for a standard five-spot petroleum
reservoir production scenario with central injector to examine how the orientation of the
well array relative to the band pattern influences production efficiency. For this
production scenario, the effects of relative permeability are considered with water as the
wetting phase and oil as the nonwetting phase. The third set of simulations prescribes
incompressible contaminant transport (mobility ratio = 1) for a point-source release to
examine the relationship of regional gradient direction to band pattern in determining the
shape and distribution of the resulting plume.
5.1. Well-to-well flow
In order to characterize the bulk effects of the CB array as mapped, we first performed
a series of 210 single-phase, incompressible well-to-well flow simulations for a fixed
flow rate using injector-producer well pairs spaced 25, 50, 75, 100, 125, 150 and 200 m
apart. At 15 midpoint locations scattered within the band pattern, two simulations were
performed for each well-spacing—one oriented generally parallel to (along) the dominant
band trend and one oriented generally normal to (across) it (Figure 7.6). For every
simulation, the pressure drop measured between the wells in the presence of the bands
was normalized by the corresponding CB-free (homogeneous, isotropic sandstone matrix)
value. The resulting normalized pressure drop data (∆P) are presented graphically in
Figure 7.7.
5.1.1. Results
The most basic observation is that the pressure drop required to drive flow in the
presence of the bands always exceeds that for the CB-free case (Figure 7.7a). With a
range from 1.7 to 4.2 and a mean of about 2.9, there is a slight trend toward increasing ∆P
with decreasing well spacing. Also, the pressure drop required to drive flow across the
dominant band trend (∆Pn) generally exceeds that required to drive flow along it (∆Pp) by
an average of about 25% (Figure 7.7b). In other words, a modest degree of
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