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Microseismic Monitoring and Geomechanical Modelling of CO2 - bris

Microseismic Monitoring and Geomechanical Modelling of CO2 - bris

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30<br />

30<br />

CHAPTER 4. A COMPARISON OF MICROSEISMIC MONITORING OF FRACTURE STIMULATION DUE TO WATER<br />

VERSUS CO 2 INJECTION<br />

330°<br />

0°<br />

30°<br />

Anisotropy [%]<br />

9<br />

8<br />

300°<br />

60°<br />

7<br />

6<br />

270°<br />

90°<br />

5<br />

4<br />

3<br />

240°<br />

120°<br />

2<br />

1<br />

210°<br />

180°<br />

150°<br />

0<br />

Fracture strike (α)<br />

180<br />

160<br />

140<br />

120<br />

100<br />

80<br />

60<br />

40<br />

20<br />

20<br />

20<br />

30<br />

40<br />

30<br />

60<br />

80<br />

40<br />

20<br />

100<br />

40<br />

30<br />

10<br />

10<br />

60<br />

100<br />

5<br />

5<br />

20<br />

1<br />

100<br />

80<br />

60<br />

3030<br />

0<br />

0 0.05 0.1 0.15 0.2<br />

Fracture density (ξ)<br />

80<br />

80<br />

100<br />

200<br />

200<br />

40<br />

20<br />

10<br />

40<br />

30<br />

60<br />

200<br />

80<br />

20<br />

60<br />

80<br />

100<br />

100<br />

200<br />

40<br />

(a)<br />

γ<br />

0.2<br />

0.18<br />

0.16<br />

0.14<br />

0.12<br />

0.1<br />

0.08<br />

0.06<br />

0.04<br />

0.02<br />

200 200 200<br />

20<br />

30<br />

40<br />

30<br />

10<br />

40<br />

5<br />

10<br />

20<br />

60 60<br />

1<br />

30<br />

5<br />

20<br />

100<br />

100<br />

80<br />

30<br />

40<br />

0<br />

0 0.05 0.1 0.15 0.2<br />

Fracture density (ξ)<br />

60<br />

80<br />

10<br />

40<br />

20<br />

30<br />

60<br />

80<br />

100<br />

40<br />

60<br />

100<br />

80<br />

(b)<br />

0.2<br />

0.18<br />

200<br />

100<br />

200<br />

(c)<br />

0.16<br />

80<br />

60<br />

0.14<br />

0.12<br />

100<br />

100<br />

40<br />

80<br />

200<br />

γ<br />

0.1<br />

0.08<br />

0.06<br />

0.04<br />

0.02<br />

80<br />

100<br />

80<br />

60<br />

0<br />

0 20 40 60 80 100 120 140 160 180<br />

Fracture Strike (α)<br />

200<br />

100<br />

200<br />

(d)<br />

Figure 4.22: Synthetic inversion for a situation with fractures striking 120 ◦ , in the same format as<br />

Fig. 4.21. This case also has subhorizontal arrivals, but with fractures striking at 120 ◦ (γ=0.04,<br />

δ=0.1, ξ=0.08 <strong>and</strong> α=120 ◦ ). The inversion accurately identifies γ <strong>and</strong> the fracture strike, but<br />

fracture density is only poorly constrained.<br />

30<br />

20<br />

40<br />

100<br />

30<br />

80<br />

60<br />

5<br />

60<br />

40<br />

10<br />

10<br />

20<br />

30<br />

80<br />

40<br />

60<br />

80<br />

100<br />

100<br />

76

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