ROCK PROPERTIES DERIVED FROM CONTINUOUS PRESSURE MONITORING IN THE ARBUCKLE GROUP OF OKLAHOMA

The Arbuckle Group is the primary saltwater disposal (SWD) zone in Oklahoma, receiving approximately 68% of the total volume of wastewater in the state. Disposal into the Arbuckle Group has been correlated to historically high seismicity in the states of Oklahoma and Kansas. Regardless of the correlation, the hydraulic properties of the geologic unit are still poorly characterized so fluid or pressure propagation cannot be accurately modeled.

Numerous inactive disposal wells with open injection intervals in the Arbuckle Group have been instrumented with pressure transducers, which have been collecting continuous pressure and temperature data since August 2016. Numerous earthquakes have occurred near the instrumented wells, such as the September 3 2016 M5.8 Pawnee earthquake, and were recorded as poroelastic responses in the monitoring wells. Tidal strain and stress from injection into nearby SWD wells are also observed in the monitoring wells. Each of these stresses and the associated responses can be used to compute material properties of the reservoir. Rock compressibility, permeability, storage coefficient, and hydraulic diffusivity computed from stress and associated responses can be used to simulate geomechanical, hydrogeological, and seismological processes. Improved understanding of the material properties may lead to better management practices and mitigation of induced seismicity.