Earthquake Studies Complicate Fracking Questions
Posted Jul. 29, 2013, 9:05 am
Tom Elias / Mirror Columnist
Bank on this: As oil drilling companies begin ramping up for large numbers of wells in the Saudi Arabian-sized Monterey Shale geologic formation, opponents will paint some doomsday scenarios.
Here’s one they will likely conjure up: Injection wells into which drillers put waste water and chemicals from their operations will somehow set off the adjacent San Andreas Fault and cause multiple earthquakes, possibly as strong as the 1906 San Francisco shock.
The drilling industry will downplay any such risk, saying they’ve used hydraulic fracturing in California for decades without producing quakes.
The issue of fracking and earthquakes took on new currency in early July, when Science magazine, the thoroughly peer-reviewed journal of the American Association for the Advancement of Science, published two studies (http://www.earth.columbia.edu/articles/view/3107, http://www.sciencemag.org/content/341/6142/117.summary). One, from UC Santa Cruz, reported that as geothermal electricity production rises in California’s Imperial Valley, so does the number of small earthquakes in that ever-shaky area where more than 10,000 temblors have been recorded since 1981.
The other, from a team of researchers at Columbia University and the University of Oklahoma, found that fracking may be one reason previously stable parts of the East and Midwest have experienced some earthquakes in recent years.
The second study raises the most questions for fracking in the Monterey Shale, which covers hundreds of square miles from eastern Monterey County south along the west side of the San Joaquin Valley and beyond.
“A recent dramatic increase in seismicity in the midwestern United States may be related to increases in deep wastewater injection,” said the Columbia/Oklahoma study.
As lead author Nicholas van der Elst of Columbia explained it, quakes in previously quiescent areas from North Dakota to Oklahoma and Pennsylvania are at least in part due to injection of waste from fracking and other oil drilling – a combination of water and a variety of chemicals – into separate wells near those producing oil.
The report said waste liquid -- used in fracking to break into shale formations and get at the oil inside – can essentially lubricate small underground faults, which then can be set off by seismic waves traveling through the earth from large and very distant quakes.
“Triggering in induced seismic zones could be an indicator that fluid injection has brought the fault system to a critical state,” the study said.
But van der Elst, who earned his Ph.D. at UC Santa Cruz, noted in an interview that rock formations in the Monterey Shale are different from most of those around oil wells elsewhere in America.
“Elsewhere, waste is rarely injected into shale, but often into sandstone below where oil is found,” he said. So he stops far short of predicting that injection wells for waste fluid in the Monterey Shale could trigger massive earthquakes on or near the San Andreas.
He notes that none of the eastern and midwestern quakes have done significant damage or killed anyone, saying “There is not necessarily greater danger in the Monterey Shale.”
Meanwhile, Tupper Hull, spokesman for the Western States Petroleum Assn., asserts that “There appears to be a fundamental difference in conditions in the Midwest and here. The area here is already saturated with water – oil production in California results in about 10 times more water coming up than oil. The water that comes up here is routinely reinjected in nearby injection wells, without any increase in earthquakes.”
Hull, therefore, insists that “There is no connection between fracking and earthquakes. Disposal of waste water in California has been handled on a routine basis for many, many years, in accordance with both state and federal laws.”
But that’s unlikely to satisfy either seismic alarmists or environmentalists fretting about the possibility of ground water pollution from fracking wastes.
So Hull says the industry expects current discussions in the Legislature of a fracking moratorium or a flat-out prohibition on fracking the Monterey Shale to produce “a more robust regulatory climate.”
Van der Elst recommends not that California stop or ban fracking, but that “there should be long-term seismic monitoring of any long-term injection site. A lot of attention should be paid to what eventually happens to the waste.”
All of which means there’s interesting evidence building in this emerging controversy. And that will make decisions on fracking even more complex.