Microseismic Monitoring and Geomechanical Modelling of CO2 - bris

5.5. SURFACE UPLIFT
1
0.9
0.8
Soft
Med
Stiff
1
0.9
0.8
1
0.9
0.8
1
0.9
0.8
0.7
0.7
0.7
0.7
0.6
0.6
0.6
0.6
K 0
0.5
γ 3
0.5
K 0
0.5
γ 3
0.5
0.4
0.4
0.4
0.4
0.3
0.3
0.3
0.3
0.2
0.2
0.2
0.2
0.1
0.1
0.1
0.1
0
1 2 3
0
1 2 3
0
1 2 3
0
1 2 3
(a)
1
1
(b)
0.9
0.9
0.8
0.8
0.7
0.7
0.6
0.6
K 0
0.5
γ 3
0.5
0.4
0.4
0.3
0.3
0.2
0.2
0.1
0.1
0
1 2 3
0
1 2 3
(c)
Figure 5.14: Numerical results for stress path parameters as a function of reservoir geometry and
stiffness for the shallower reservoirs. This figure is in the same format as Figure 5.9.
In Table 5.4 I give the maximum amounts of uplift above each reservoir. However it is difficult
to compare these results as the reservoirs have different pore pressure changes, so in Table 5.5 I give
the uplift normalised by the reservoir pore pressure change for both the deep and shallow reservoirs.
The centimetres of uplift above the extensive reservoirs and the millimetres of uplift above the thin
reservoirs would be detectable even in more challenging environments. The sub-millimetre amounts of
uplift above the small hard and medium reservoirs may be difficult to detect even in good conditions.
The normalised amounts of uplift are similar between deep and shallow cases, in some cases uplift
is larger for the deep case while in some uplift is larger for the shallow case. It is not clear what causes
this variation. The amount of uplift correlates with the volume of CO 2 injected, which is largest for
the extensive case and lowest for the small reservoir. The overburden stiffness for the medium and soft
cases are identical (Figure 5.7) yet a much larger amount of uplift is found above the soft reservoir,
suggesting that the stiffness of the reservoir is a strong control on the amount of uplift expected.
However, the soft overburden above the hard reservoirs leads to a greater amount of uplift than above
the medium case, implying that the stiffness of the overburden is also important.
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