Probabilistic assessment of uncertainties in induced seismic potential
of the San Juan Basin CarbonSAFE Phase III deep saline carbon
sequestration site
Abstract
Although geologic carbon sequestration projects have yet to induce – or
may never induce – a damaging earthquake, experiences from other deep
injection industries such as hydraulic fracturing, enhanced geothermal
systems, and saltwater disposal suggest that effective quantitative
seismic risk assessment is necessary for deep saline carbon capture and
sequestration (CCS) projects. One such imminent CCS project is the San
Juan Basin CarbonSAFE Phase III program. The study detailed in this
paper utilizes Monte Carlo probabilistic geomechanical analyses combined
with observations of the geological and operational parameters of the
San Juan Basin site and suggests that this project is of low induced
seismic risk. The primary analysis is split into four sections. First,
we assessed the literature for faults and past seismicity, and at least
five faulting scenarios are directly relevant. Second, we developed and
calibrated an integrated earth model for the project site. Third, we
performed Monte Carlo simulations that considered reasonable
uncertainties of the geomechanical parameters. Only the Hogback flexural
faulting scenario presented high Coulomb failure functions, but fourth,
we determined the risk to be low based on the combined lack of
historical seismicity, the geological framework of the flexural faults,
and the presence of saltwater injection at the same depth as the
proposed supercritical carbon dioxide injection. The most sensitive
parameters in the geomechanical calculations were the fault dip and the
coefficient of friction. The least sensitive were the fault strike and
the orientation of the maximum horizontal principal stress.