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Microseismic Monitoring and Geomechanical Modelling of CO2 - bris

Microseismic Monitoring and Geomechanical Modelling of CO2 - bris

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7.4. SUMMARY<br />

7.4 Summary<br />

• I have developed a workflow to map changes in stress computed by geomechanical simulation<br />

into changes in the dynamic elastic stiffness tensor <strong>of</strong> the reservoir <strong>and</strong> overburden rocks. The<br />

models can be initialised such that the dynamic stiffness match the geomechanical stiffnesses (or<br />

a multiple there<strong>of</strong>).<br />

• The workflow can also model the effects <strong>of</strong> fractures <strong>and</strong> <strong>of</strong> fluid substitution.<br />

• I have computed the changes in overburden two-way travel time above the simple reservoirs. I<br />

find that where stress arching occurs an increase in vertical P-wave velocity leads to a detectable<br />

travel time decrease.<br />

• I have also made predictions about anisotropy induced by stress changes. The amount <strong>of</strong> splitting<br />

predicted may be difficult to observe, but does indicate how anisotropy could provide a useful<br />

indicator <strong>of</strong> reservoir compartmentalisation.<br />

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