The top geologists in Colorado and Oklahoma, two states with significant shale resources, say researchers with the U.S. Geological Survey (USGS) were hasty in suggesting that injection wells used to dispose of wastewater from oil and gas drilling are responsible for an increase in earthquakes in the Midcontinent region.
Earlier this month, scientists from the USGS earthquake research center in Menlo Park, CA, released an abstract stating they believed a six-fold increase in the number of earthquakes of 3.0 magnitude or greater since 2001 -- over 20th century levels -- were caused by an increase in oil and gas activity (see Shale Daily, April 2).
"I think it's really premature," Vince Matthews, Colorado's state geologist and director of the Colorado Geological Survey, told NGI's Shale Daily on Monday. "They were supposedly doing a study for the [U.S. Environmental Protection Agency], and I was looking forward to the results of that.
"Suddenly in the press we start getting all of these interviews regarding this abstract, which none of the other state geologists in the Midcontinent knew about. I think there are others that are concerned about these press releases and the validity of their conclusions."
In a written statement, Randy Keller, Oklahoma's state geologist and director of the Oklahoma Geological Survey, echoed that sentiment.
"We consider a rush to judgment about earthquakes being triggered to be harmful to state, public, and industry interests," Keller said. "We are taking a measured and scientific approach to addressing issues so that any conclusion that earthquakes are linked to oil and gas activities can be scientifically defensible.
"It is true that the past few years have seen a significant increase in earthquake activity within Oklahoma. While we are studying the possibility that some of this activity could be related to oil and gas operations, it is unlikely that all of the earthquakes can be attributed to human activities. It is, however, possible that there have been incidents of triggered seismicity within Oklahoma over the past several years."
Although environmental groups hailed the USGS's initial claims, supporters of the oil and gas industry and Interior Department Deputy Secretary David Hayes have also taken issue with the abstract (see Shale Daily, April 12).
Keller said it was important to remember that earthquake processes in the stable interior of continents take hundreds to tens of thousands of years to occur, yet meaningful earthquake monitoring has only been technologically possible for about 40 years.
Matthews concurred. "If you took the same 40-year period from 1770 to 1812, you would find that there was an increase in seismicity in that part of the country, culminating in a couple of magnitude 8.0 earthquakes," he said. "You could correlate those earthquakes back in the 1700s and 1800s with the amount of acreage that was being cleared for farmland. Was that what caused those large earthquakes in 1811 and 1812? You have a short time period, you're trying to cover a broad territory and you're coming to a sweeping conclusion. It's a stretch.
"[But] the issue of earthquakes -- where they could conceivably be triggered by oil and gas fluid injection, CO2 sequestration or geothermal activities -- is an extremely important one. And it's too important to be done in the mainstream media. It really needs a lot of serious scientific investigation."
One of the areas of increased seismicity USGS researchers have been focusing on is a coalbed methane field in the Raton Basin, which is located along the Colorado-New Mexico border, just west of Trinidad, CO. Matthews said there were stark differences between injections wells at Trinidad and at three other areas in the state: Paradox Valley, Rangely and the Rocky Mountain Arsenal.
"The wastewater that's being injected in Trinidad is not going in under pressure, as it was at those other locations," Matthews said. "That's a huge difference. The USGS also said that when the injections were stopped at the other locations, the earthquakes stopped. Well, the injections in Trinidad haven't stopped, they have been continuing at exactly the same rate. And yet the earthquakes did stop on that fault.
"There are these tremendous differences that, as a scientist, I don't like reading about in press releases. I want to see the theory and the data. I want to know if we can make conclusions that really make sense and are well supported by theory and by data. And there's a lot of good data that's being collected right now, most of it from the industry."
USGS researchers plan to discuss the increase in earthquakes at the annual Seismological Society of America (SSA) conference, which is being held today (Tuesday, April 17) through Thursday in San Diego. The USGS presentation, entitled "The M5.8 Central Virginia and the M5.6 Oklahoma Earthquakes of 2011," is scheduled for Wednesday at 3:45 p.m.
Last month Ohio regulators said a dozen small earthquakes in northeastern Ohio over the last year may have been triggered by a wastewater disposal well in Youngstown (see Shale Daily, March 12). In 2011, Arkansas established a moratorium on wastewater disposal wells in an area of the Fayetteville Shale after similar quake activity was reported there (see Shale Daily, July 29, 2011; March 4, 2011).