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Eastern Section Meeting

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Monitoring Microseismicity Around Wastewater Injection Wells and at the Onset of Unconventional Oil and Gas Production in the Rome Trough, Eastern Kentucky

Abstract

In the central and eastern United States, felt earthquakes likely triggered by fluid injection from oil and gas production or wastewater disposal have dramatically increased in frequency since the onset of the shale gas boom. Studies suggest the likely culprit in these cases is large-volume wastewater injection over time where favorably oriented, preexisting faults are brought to failure conditions by increases in pore-fluid pressures. Hydraulic fracturing has also been linked to some felt events. In the Rome Trough of eastern Kentucky, fracture stimulations (primarily using nitrogen and at relatively shallow depths) and wastewater injection are ongoing. Unlike in states surrounding and near to Kentucky (e.g., Ohio, West Virginia, and Arkansas), no events related to oilfield operations have been reported felt or detected by the regional seismic network operated by the University of Kentucky.

Interest is emerging in development of the deep Cambrian Rogersville Shale in the Rome Trough that would use horizontal drilling and high-volume hydraulic fracturing. To characterize conditions that might lead to induced or triggered events, the Kentucky Geological Survey is conducting a study to establish background seismicity levels prior to the onset of large-scale oil and gas production and wastewater injection. KGS will deploy a temporary network of sensitive seismographs in the vicinity of dense clusters of Class II wastewater injection wells and near the locations of new, deep oil and gas test wells in eastern Kentucky. KGS is collaborating with the University of Kentucky Department of Earth and Environmental Sciences, with an instrument manufacturer, Nanometrics, and with industry to conduct the monitoring and research. Instruments provided by the industry partner and Nanometrics will augment the KGS backbone network to increase the sensitivity. The study involves a minimum of 15 stations in the project area. Installation of the network has begun and should largely be in place by September, 2015.