Environmental Engineering Reference
In-Depth Information
(a)
(b)
Figure 7.20.
Cumulative production and evolution of reservoir pressure at the two most
important productive levels of Ravenna terra reservoir
We have tried to simulate the formation of a reversed subsidence bowl in an
axisymmetric model reservoir with a radius of 2,000 m, thickness of 80 m, and mean
burial depth of 1,840 m. The reservoir is overlaid by a cap rock 10 m thick, with the
remaining depth being comprised of sand. An edge aquifer is also present.
For the simulation we have used a two-step model. First, by assuming
oedometric conditions we have predicted compaction at the reservoir center and
boundary during the production period and period afterward. For instance, the
resulting stress path for the reservoir center during the gas production period due to
gas expansion with a pressure decline of 8 MPa (see Figure 7.20) is path A-B in
Figure 7.21a. The ensuing volumetric compaction is 0.95/1.35 = 0.70%.
