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