Microseismic Monitoring and Geomechanical Modelling of CO2 - bris

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1
1
1
1
1.5
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CHAPTER 3.
INVERTING SHEAR-WAVE SPLITTING MEASUREMENTS FOR FRACTURE PROPERTIES
270°
300°
240°
330°
210°
0°
180°
30°
150°
60°
120°
Anisotropy [%]
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
90°
(a)
180
160
140
2
0.3
0.3
1
0.25
1.5
1.5
0.25
120
1.5
0.2
1
0.2
1.5
Frac strike
100
80
2
1.5
1
1.5
Gamma
0.15
1
Gamma
0.15
2
1
1
60
40
20
2
2
1.5
0.1
0.05
2
1.5
0.1
0.05
1
1.5
1.5
1.5
0
0 0.05 0.1 0.15 0.2
Frac density
1
0
0 0.05 0.1 0.15 0.2
Frac density
0
0 50 100 150
Frac strike
1
(b) (c) (d)
0.3
2
0.3
2
0.25
2
2
1.5
0.25
2
1.5
0.2
2
0.2
1
Delta
0.15
2
1.5
1
Delta
0.15
0.1
0.1
0.05
1.5
1
0.05
1
0
0 0.05 0.1 0.15 0.2
Frac density
(e)
0
0 0.05 0.1 0.15 0.2 0.25 0.3
Gamma
(f)
Figure 3.9: Splitting inversion results for Phase IB, assuming one fracture set is present. Panel
(a) shows the observed and modelled SWS in the same format as Figure 3.5a. In (b)-(f) I show
the normalised misfit contours as a function of ξ, α, γ and δ. The 90% confidence limit is marked
in bold, and the dotted lines mark the best fit values. The inversion images the strike and density
of a fracture set, and suggests that there is little VTI fabric.
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