Hydraulic properties of injection formations constrained by surface deformation
Published Web Locationhttp://dx.doi.org/10.1016/j.epsl.2019.03.025
Wastewater injection over the past decade has increased seismicity in the central USA, in some cases accompanied by detectable surface uplift. Here, we use this uplift to constrain subsurface properties and pore pressure evolution. We apply an advanced multitemporal interferometric algorithm to 35 synthetic aperture radar images acquired by ALOS satellite over four years before the 2012 earthquake sequence in east Texas, where large volumes of wastewater are disposed at depths of ∼800 m and ∼1800 m. To solve for the hydraulic diffusivity of the injection layers, we jointly inverted the injected volume and uplift data, considering a poroelastic layered half space. We find diffusivity values of 0.3±0.1 m 2 /s and 0.7±0.15 m 2 /s for shallow and deep injection layers, respectively, which combined with seismically-derived bulk moduli yields permeability values of 5.5±2.6×10 −14 m 2 and 1.9±0.25×10 −13 m 2 for these layers, consistent with permeability range reported for Rodessa formation and well test values. Hydraulic conductivity determines the evolution of pore pressure and thus the origin and location of induced seismicity. This study highlights the value of geodetic observations to constrain key hydrogeological properties of injection layers and to monitor the evolution of the subsurface pressure change.