Microseismic Monitoring and Geomechanical Modelling of CO2 - bris

CHAPTER 2.
THE WEYBURN CO 2 INJECTION PROJECT
that they detect nothing. Other monitoring techniques deployed at Weyburn, such as soil gas flux
monitoring and shallow aquifer sampling, are similar in the way that detection of nothing represents
a success.
Should the lack of microseismicity seen at Weyburn always be expected for CO 2 injection scenarios
It has been suggested that, as it has a lower compressibility, CO 2 will have an inherently lower
seismic deformation efficiency than other common injection fluids such as water. Seismic deformation
efficiency describes the ratio between the energy used in pumping a fluid into the formation and the
total seismic energy recorded on the geophones (e.g., Maxwell et al., 2008). If this is the case, then
microseismic monitoring is less likely to be useful for CCS activities. Alternatively, there may be
geomechanical explanations for the lack of microseismic activity at Weyburn. In the following chapter
I will discuss shear wave splitting measurements made on the Weyburn microseismic data, developing
a novel approach to invert splitting measurements for fracture properties. I will then switch my focus
from the microseismic data and instead seek to explain the lack of it. To do this I will consider another
microseismic dataset from a different CO 2 injection site, and construct representative geomechanical
models that approximate the Weyburn reservoir.
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