Hydraulic fracturing extracts methane from deep wells in shale deposits. A new National Academies study considers whether the technology induces local earthquakes. Credit: Wikimedia.
A new study by the National Academies examines the risk of induced earthquakes caused by hydraulic fracturing and other underground energy technologies, such as carbon dioxide capture and sequestration, geothermal energy and conventional oil and gas recovery. The report is Induced Seismicity Potential in Energy Technology, and prepublication copies are available through the NAS online catalog.
Hydraulic fracturing—or fracking—involves pumping a mix of water, proppants and chemicals under high pressure into deep underground shale deposits. The shale fractures and releases natural gas, which flows back up the well along with some of the wastewater. One of the wastewater disposal methods is to inject it underground at a different site.
With each of the energy technologies considered by the committee, there is a net deposit or withdrawal of fluids, and “all have at least the potential to induce earthquakes that could be felt by people.” According to a NAS press release, there has been no reported loss of life or significant damage from earthquakes induced by energy technologies, but local residents are understandably concerned.
The study found that fluid balance is the key to avoiding induced earthquakes. From the press release, “technologies designed to maintain a balance between the amounts of fluid being injected and withdrawn, such as most geothermal and conventional oil and gas development, appear to produce fewer induced seismic events than technologies that do not maintain fluid balance.”
It is not clear, yet, whether carbon capture and sequestration might induce earthquakes because no large-scale projects exist at present, and the committee notes that more research is needed in this area.
So far, the report says, the federal and state agencies responsible for regulatory oversight have reacted successfully to energy-related seismic events, but the committee urges interagency cooperation as these energy technologies grow.
The report was commissioned by DOE.