AN OVERVIEW OF RECENT INJECTION INDUCED SEISMICITY IN THE CENTRAL AND EASTERN UNITED STATES

The sharp increase in earthquakes in the Central and Eastern United States over the past decade has primarily been attributed to large volume fluid injection associated with enhanced oil and gas recovery. In this presentation, we will provide an overview of the findings from various studies characterizing human-induced seismicity across the region with comparisons to tectonic seismicity. The majority of induced seismicity and the largest magnitude earthquakes have been the result of disposal of produced and flowback water, but there has also been a prominent amount of seismicity caused directly by hydraulic fracture stimulations. Proximity of fluid injection to mature faults optimally oriented in the stress field appears to be a key ingredient for generating seismicity. However, fault identification can be difficult prior to injection, particularly in the predominantly strike-slip settings. Observational studies point to the injection flux (volume per area per time) being a key factor raising the likelihood of induced seismicity. This is supported by modeling studies that identify the seismicity rate being driven by the rate of change in pore fluid pressure. These findings provide some guidance in terms of best practices for mitigating the hazard via regulatory and operational strategies, but ultimately broader integration with geomechanical, hydrological, and structural datasets will be necessary. It will be important to continue to learn lessons from the ongoing large-scale fluid injection “experiment” to better understand the hazards associated with even larger volume injection that will be necessary to make carbon sequestration economically viable.