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concentrated where faults and ZBs are not spread out. It flow but allow the fault parallel one. This mixed
means that the CSBs generally do not have relevant conduct/barrier behavior is shown in the bottom left
compartmentalization properties. Those structures can side of the model (Fig. 10 b) and is in agreement with
buffer the flow, but since they are discontinuous in both previous studies made for sandstones (Aydin, 2000).
horizontal and vertical direction their effect is The second test showed that most of the flow is
negligible already at an outcrop scale. Those results are concentrated in the Southeast quadrant of the model
in agreement with previous works on sandstones (e.g. where only a few impermeable structures are present.
Antonellini & Aydin, 1995; Ahmadov et al., 2007; The barrier effect of ZBs is clearly shown by the path
Fossen & Dale, 2007). On the other hand ZBs can act of the flow lines directing toward the top right corner of
as barrier to fluid flow, this attitude can result into the model (Fig. 11 b, c). The aforementioned lines
either deviation of the fluid flow or abrupt change in its deviate around the ZBs adjacent to the point imposed to
velocity (Fig. 10 b). Faults show a dual behavior, have a hydraulic head of 10 m. Fault-perpendicular
indeed these structures inhibit the fault-perpendicular flow in inhibited also in this case, indeed the top left

Figure 11: Fluid flow simulations within the volumes of Fig. 9. a) Steady state simulation: central head
point 10 m, four corners heads 2 m; color legend values are expressed in meters. b) Flow in the N-S
direction (yy), color scale values are expressed in m3/day. c) Flow in the E-W direction (xx), color scale
values are expressed in m3/day. Note the concentration of flow lines in (b) and (c) from the center towards
the south-east corner, which is an area of high hydraulic conductivity.

Stanford Rock Fracture Project Vol. 24, 2013 E-12