Hydraulic Properties of Injection Formations in Eastern Texas Constrained by Surface Deformation

Date: 4/26/2019

Time: 09:00 AM

Room: Cascade I

Wastewater injection over the past decade has increased seismicity in the central USA, in some cases accompanied by detectable surface uplift. Here, we show that the uplift rate is controlled by the hydraulic diffusivity of the injection medium and thus we can 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 a 4-year period 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 m²/s and 0.7+-0.15 m²/s for shallow and deep injection layers, respectively, which combined with seismicity-derived bulk modulii yields permeability values of 5.5x10^-14 m² and 1.9x10^-14 m² 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 importance of geodetic observations to constrain key hydrogeological properties of injection layers and to monitor the evolution of the subsurface pressure change.

Presenting Author: Manoochehr Shirzaei

Authors