NRC studies earthquake risk from hydraulic fracturing

June 25, 2012
Hydraulic fracturing, as currently used by the oil and gas industry for unconventional natural gas projects, poses little risk for inducing earthquakes that can be felt by people, the National Research Council (NRC) said in a recent report.

Hydraulic fracturing, as currently used by the oil and gas industry for unconventional natural gas projects, poses little risk for inducing earthquakes that can be felt by people, the National Research Council (NRC) said in a recent report.

Researchers noted the number of seismic events associated with unconventional oil and gas activities have been "very few" given that 35,000 fractured shale gas wells exist in the US.

Carbon capture and storage projects have greater potential for inducing seismic events because significant volumes of fluids are injected underground over long periods, the report said.

Insufficient information exists to fully understand the potential earthquake risk for future large-scale CCS projects, researchers said.

The US Department of Energy sponsored the study after it was requested by Sen. Jeff Bingaman (D-NM) in June 2010. Bingaman is chairman of the Senate Energy and Natural Resources Committee.

DOE asked NRC to examine the scale, scope, and consequences of seismicity induced during the injection of fluids related to energy development and production.

"Recently, several induced seismic events related to energy technology development projects in the US have drawn heightened public attention," said the final report released June 15.

A committee examined the potential for shale gas recovery, CCS, geothermal energy production, and conventional oil and gas development to cause earthquakes.

In particular, researchers sought a better understanding of the probable physical mechanisms of inducing seismic events.

"Since the 1920s, we have recognized that pumping fluids into or out of the Earth has the potential to cause seismic events that can be felt," the report said.

The study did not attempt to calculate property damages and did not consider the possibility of water contamination.

Earthquake prediction difficult

The ability to predict induced seismicity at a particular energy project relies on both theoretical modeling and available field measurements, the report said.

Researchers considered pressure of fluids in the pores of the rocks at depth and pore pressure changes along with the rates and volumes of fluids being injected or withdrawn.

"While scientists understand the general mechanisms that induce seismic events, they are unable to accurately predict the magnitude or occurrence of these earthquakes due to insufficient information about the natural rock systems and a lack of validated predictive models at specific energy development sites," the report said.

The factor most directly correlated with induced earthquakes is the total balance of fluid introduced or removed underground, the committee said.

Because oil and gas development, CCS, and geothermal energy production each involve net fluid injection or withdrawal, all have at least the potential to induce earthquakes.

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.

Numerous federal and state agencies have regulatory oversight related to different aspects of underground injection activities associated with energy technologies. The committee issuing the report said interagency cooperation is warranted given expanding energy development.

Seismic events caused by or likely related to energy development have been measured and felt in Alabama, Arkansas, California, Colorado, Illinois, Louisiana, Mississippi, Nebraska, Nevada, New Mexico, Ohio, Oklahoma, and Texas, the report said.

Abroad, the UK government has looked into events around a Cuadrilla Resources Ltd. shale-gas well near Poulton-le-Fylde (OGJ Online, Nov. 3, 2011).

Cuadrilla commissioned the study that found a high probability that hydraulic fracturing of its Preese Hall-1 well triggered seismic events. The well was completed in a Bowland basin shale, which Cuadrilla has said might hold 200 tcf of gas in place in its 437-sq-mile license area between Blackpool and Preston (OGJ Online, Sept. 22, 2011).

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About the Author

Paula Dittrick | Senior Staff Writer

Paula Dittrick has covered oil and gas from Houston for more than 20 years. Starting in May 2007, she developed a health, safety, and environment beat for Oil & Gas Journal. Dittrick is familiar with the industry’s financial aspects. She also monitors issues associated with carbon sequestration and renewable energy.

Dittrick joined OGJ in February 2001. Previously, she worked for Dow Jones and United Press International. She began writing about oil and gas as UPI’s West Texas bureau chief during the 1980s. She earned a Bachelor’s of Science degree in journalism from the University of Nebraska in 1974.