Fracking and Seismic Activity
January 12, 2012
Q1: Recent earthquake tremors centered on Youngstown, Ohio, have resurrected safety concerns related to hydraulic fracturing and shale gas extraction. Are the tremors related to fracking activity?
A1: Under the right conditions, every time pressure is applied or reduced from an underground rock formation there is at least a small risk of a seismic result. This is true in the case of mining activity, driving piles for bridge or building construction, drilling geothermal wells, or injecting fluids at high pressure in seismically active areas. According to the recent report by the Secretary of Energy Advisory Board Shale Gas Production Subcommittee, tiny micro earthquakes can be triggered during shale gas development; however, most of these are minuscule and pose no public health or safety hazard (see the subcommittee’s Second Ninety Day Report, November 18, 2011, at http://www.shalegas.energy.gov/resources/111811_final_report.pdf).
The recent seismic activity in Youngstown has been attributed to the injection of wastewater from nearby oil and gas drilling, not from fracking operations. Under EPA and state regulations, disposal of such wastewater requires injection in permitted Class II injection wells, an activity that has been going on for decades. In cases where large volumes of water are injected under pressure in seismically active areas, as the water enters fissures, it lubricates fault lines that can slip, causing tremors. The wells in question have been closed pending further investigation. Reports indicate that the sites have been accepting brine disposal since 2010, but that the injected volumes grew tremendously in 2011.
Q2: What can be done to reduce risk of seismic activity from the injection at wastewater wells?
A2: In the days immediately following the recent seismic activity in Youngstown, Ohio’s Department of Natural Resources closed the injection well nearest the epicenter of the December 31 earthquake and also suspended activity at four other nearby injections wells to more fully evaluate the situation. That said, regulators and operators can take, and are already taking, a number of actions to reduce the future likelihood of seismic activity from wastewater injection, including assessing seismic risk when identifying or permitting injection sites, requiring seismic monitoring at active well sites, and limiting well pressure thresholds by decreasing the amount of water pumped into wells as well as the pressure at which it is pumped. Discussions are also under way about whether and how to handle the issue of large-volume injection at or near fault zones.
Q3: What other options exist for the disposal of wastewater?
A3: Wastewater from natural gas extraction cannot be discharged directly into waterways without undergoing treatment. The EPA is developing natural gas wastewater standards for water that is taken to wastewater treatment facilities as some plants are not properly equipped to handle the wastewater. Another important option is to recycle and re-use wastewater, thereby reducing the volumes that ultimately must be disposed of in injection wells. Technological advancements are increasingly making this cost-competitive option. In addition, firms are now developing and employing “green” frack components, finding better ways to treat and recycle liquids flow, and exploring ways to reduce the amount of water used in fracking operations through advanced minimization technologies—all of which could result in the generation of less wastewater (see the National Petroleum Council’s White Paper, “Management of Produced Water for Oil and Gas Wells,” at http://www.npc.org/Prudent_Development-Topic_Papers/2-17_Management_of_Produced_Water_Paper.pdf).
Frank A. Verrastro is senior vice president and director of the Energy and National Security Program at the Center for Strategic and International Studies (CSIS) in Washington, D.C. Lisa Hyland is research associate and program manager of the CSIS Energy and National Security Program. Molly Walton is research associate and program coordinator with the CSIS Energy and National Security Program.
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