(Updates with analyst comment in fifth paragraph, Richter scale definition in 12th.)
Jan. 11 (Bloomberg) -- Drilling for shale gas in the U.K. won’t cause dangerous earthquakes and poses little risk to the environment given appropriate safeguards, scientists said.
“Most geologists think this is a pretty safe activity,” Mike Stephenson, head of energy science at the British Geological Survey, said at a briefing in London yesterday. “We think the risk is pretty low and we have the scientific tools to tell if there is a problem.”
Hydraulic fracturing, a process using water, sand and chemicals to open fissures in rocks and release natural gas, has made the U.S the world’s largest natural-gas producer while raising concerns that the technique pollutes drinking water and causes earthquakes. Exploration was suspended in northwest England last year after fracturing gas wells caused two tremors.
Fracking, as the process has become known, is unlikely to start earthquakes stronger than magnitude 3.3 on the Richter scale, a level that typically causes no damage to property, and most will be around magnitude 2, said Peter Styles, a professor of applied and environmental geophysics at Keele University.
Scientists have also developed models linking the volume of water used during a fracking injection and the scale of earthquake caused, Bernstein & Co. analyst Bob Brackett said in a Jan. 6 note. An injection of 10 million gallons or less is unlikely to cause an earthquake exceeding magnitude 4, he said, citing U.S. Geological Survey geologist Arthur McGarr.
More Than Iraq
The U.K. could have more shale gas the previously thought, Stephenson said. The British Geological Survey is reviewing its estimates for U.K. onshore shale gas resources. The survey originally estimated that there is about 150 billion cubic meters of shale gas onshore, compared with about 300 billion cubic meters of conventional gas resources.
Cuadrilla Resources Ltd. says it’s found more natural gas trapped in the shale rock around Blackpool in northwest England than Iraq has in its entire reserves.
“There is much more shale than we thought under Blackpool,” the British Geological Survey’s Stephenson said at the briefing, adding more research remains to be done on the impact of fracking.
The debate over shale drilling in the U.S. and Europe has intensified in recent months following tremors near wastewater disposal sites in Ohio and concerns about water pollution in Pennsylvania. The U.S. Environmental Protection Agency is studying the effects of fracking on drinking water with an eye on possible nationwide regulations.
Styles said he has examined seismic data from 30 years of coal mining in the English midlands to assess the threat from fracking. The research suggests there is a “low” probability of unconventional gas drilling operations causing major earthquakes, he said.
The rock drilled by Cuadrilla, the company that caused last year’s earthquakes, is similar to that found at the country’s major coal-mining sites, suggesting potential tremors will be of a similar or lesser magnitude, he said.
“There’s not an exact analogy to coal mining, but the seismicity is remarkably similar,” Styles said at the briefing organized by the Science Media Center. “If there are going to be others, they will be about this magnitude and because they’re of that magnitude they’re very unlikely to cause damage.”
The first tremor set off by Cuadrilla was on April 1 and measured magnitude 2.3 on the Richter scale. A weaker quake of 1.5 was recorded in May. Earthquakes of magnitude 3.9 or less on the scale are considered minor or micro, while anything under 4.9 is described as light and is unlikely to cause major damage.
--Editors: Will Kennedy, Randall Hackley
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