  Fluid injection can induce seismicity by altering stresses on pre-existing
faults. Here, we investigate minimizing induced seismic hazard by optimizing
injection operations in a physics-based forecasting framework. We built a 3D
finite element model of the poroelastic crust for the Raton Basin, Central US,
and used it to estimate time dependent Coulomb stress changes due to ~25 years
of wastewater injection in the region. Our finite element model is complemented
by a statistical analysis of the seismogenic index (SI), a proxy for critically
stressed faults affected by variations in the pore pressure. Forecasts of
seismicity rate from our hybrid physics-based statistical model suggest that
induced seismicity in the Raton Basin, from 2001 - 2022, is still driven by
wastewater injection. Our model suggests that pore pressure diffusion is the
dominant cause of Coulomb stress changes at seismogenic depth, with poroelastic
stress changes contributing about 5% to the driving force. Linear programming
optimization for the Raton Basin reveals that it is feasible to reduce seismic
hazard for a given amount of injected fluid (safety objective) or maximize
fluid injection for a prescribed seismic hazard (economic objective). The
optimization tends to spread out high-rate injectors and shift them to regions
of lower SI. The framework has practical importance as a tool to manage
injection rate per unit field area to reduce induced seismic hazard. Our
optimization framework is both flexible and adaptable to mitigate induced
seismic hazard in other regions and for other types of subsurface fluid
injection.
