Microseismic Monitoring and Geomechanical Modelling of CO2 - bris

CHAPTER 1.
INTRODUCTION
In Chapter 6 I develop a microstructural model to map changes in stress predicted by geomechanical
models into changes in elastic stiffness (from which seismic velocities can be computed). This model is
fully anisotropic and includes the nonlinear response of velocity to stress changes. I have calibrated this
model with over 200 stress-velocity measurements from the literature. In Chapter 7 I demonstrate
this approach by forward modelling the changes in P-wave travel time and shear wave anisotropy
from the simple models developed in Chapter 5, with the intention of seeing whether different styles
of geomechanical deformation can be differentiated using seismic observations.
Through Chapters 5 to 7 I have outlined a workflow to go from the development of a geomechanical
model to the prediction of changes to seismic properties caused by deformation. In Chapter 8 I bring
this workflow together and demonstrate it in its entirety by developing geomechanical models of the
Weyburn reservoir. By comparing predicted microseismic event locations with observations made in
Chapter 2, and splitting predictions with measurements made in Chapter 3, the geomechanical models
can be groundtruthed, and the most appropriate models selected. These geomechanical models aid
the understanding of the microseismic observations made in Chapters 2 and 3. They help to show
that the injection of CO 2 at Weyburn can be understood, and that there is little risk of leakage.
Finally, in Chapter 9 I present the main conclusions of this project, highlighting the significant
contributions made towards the improved understanding of geological storage of CO 2 , and I also make
recommendations for future work.
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