Microseismic Monitoring and Geomechanical Modelling of CO2 - bris

4.4. SHEAR WAVE SPLITTING
50
−3
Event Magnitude
−3.2
−3.4
−3.6
−3.8
40
30
20
10
Injection pressure (MPa)
−4
0 20 40 60 80 100
0
120
Time (minutes)
(a)
50
−3
Event Magnitude
−3.2
−3.4
−3.6
−3.8
40
30
20
10
Injection pressure (MPa)
−4
0
0 10 20 30 40 50 60 70
Time (minutes)
(b)
Figure 4.10: Surface injection pressures (dotted line) and event magnitudes (crosses) through time
for water (a) and CO 2 (b) injection. There appears to be correlation between event magnitudes
and injection pressures during both stages. Injection pressures and event magnitudes are similar
for both stages, although events are distributed more evenly during water injection.
orientation of the ticks represents the fast direction, with horizontal ticks indicating that ψ is parallel
to the S H axis, while the size of the ticks indicates the magnitude of δV S . Most of the arrivals recorded
during Stage 4 have propagated subhorizontally through the reservoir. As such, ψ will represent a
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