Up to 10 percent of Okla. quake surge comes from fracking -- state scientist This EnergyWire story was sent to you by: [email protected] [EnergyWire] AN E&E PUBLISHING SERVICE EARTHQUAKES: Up to 10 percent of Okla. quake surge comes from fracking -- state scientist Mike Soraghan, E&E reporter Published: Friday, October 31, 2014 Oklahomas state seismologist said yesterday that up to 10 percent of the surge in earthquakes in his state could have been caused by hydraulic fracturing rather than wastewater disposal. Its more common than currently recognized, Austin Holland, seismologist at the Oklahoma Geological Survey, said at a forum on man-made earthquakes at the Washington offices of the U.S. Energy Association. Up to 2 percent of completed wells may have earthquakes associated with that completion process. But he said he believed the fracturing-related quakes are scattered around the edges of the states earthquake zones and not responsible for any of the major swarms of seismicity in the state. Oklahoma has had more earthquakes than California this year, and scientists have linked most of them to disposal of drilling wastewater. The state had three earthquakes yesterday. Within the debate about man-made earthquakes linked to oil and gas production, there is a sub-debate on whether fracking causes earthquakes of significant magnitude or in significant numbers. U.S. Geological Survey scientists and many of their academic colleagues say the specific process of fracturing -- injecting fluid underground at high pressure -- does not cause earthquakes that present a hazard. It is earthquakes caused by disposal, they say, that really present a hazard. Fracking quakes are considered something of a distraction (EnergyWire, April 23, 2012). But the scientist who oversees USGSs earthquake hazards program muddied that a little himself yesterday when he noted that fracking has been linked to a magnitude-4.2 quake in a remote area of Alberta. Magnitude 4.0 is roughly the level that seismologists expect to start seeing significant damage. These are very rare and present a challenge to understanding this, Bill Leith said. Fracking is only rarely the cause of felt earthquakes. Earthquakes have also been linked to the fracturing process in England, British Columbia and Ohio. Leith said USGS avoids talking about hydraulic fracturing and earthquakes in Oklahoma because many of the quakes in the state have been linked to a production practice that involves no fracking. Its called dewatering and involves pumping water out of declining oil fields to free up remaining crude. Dewatering creates as much as 1,000 times more water than oil, and many wells have a ratio thats as much as 200 times higher than conventional wells (EnergyWire, July 14). But Holland said hydraulic-fracturing-related earthquakes present a great research opportunity because drilling companies gather precise information on their fracturing work. They collect more data, and its more precise than the data on their disposal of wastewater. We are looking at using potential cases of induced seismicity as sort of these virtual laboratories, he said. Hydraulic fracturing, because its easy to identify and has a lot more data, may be a great source for these virtual observatories. Holland said he is working on a scientific paper detailing his findings on fracturing and earthquakes but keeps getting delayed by new earthquakes deserving of study. Also yesterday, a top Exxon Mobil Corp. engineer said his company is doing risk analysis for earthquake potential for each of the handful of disposal wells it drills each year. We do this for every one of our wells now, said Kris Nygaard, Exxons recognized expert on hydraulic fracturing and similar processes. Plans for two wells, he said, have been changed as a result. Nygaard said Exxon realizes that earthquakes generate a lot of concern among the public. People are bothered when theres shaking going on, he said, and they want it to stop.
Posted on: Fri, 31 Oct 2014 18:10:55 +0000
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