Fracking and earthquakes in Oklahoma

Posted by Christine, April 21, 2015

Sarah Terry-Cobo covers energy, health care and other topics for The Journal Record. You can reach her at sarah.terry-cobo@journalrecord.com.

NORMAN – Oil and gas wastewater disposal wells are very likely triggering the majority of earthquakes in northern and central Oklahoma, said Austin Holland, state seismologist.

However, due to the large number of disposal wells and earthquakes in that region, it’s difficult for scientists to prove that a specific disposal well has caused particular seismic swarms, according to a statement by the Oklahoma Geological Survey obtained by The Journal Record.

Other scientists have pointed to the likely correlation between the Sooner State’s exponential temblor increases. The OGS statement represents an evolution of scientific understanding, Holland said. At the end of 2014, the earthquake rates shot through the roof. There are about 2.5 earthquakes greater than magnitude 3.0 each day, which is about 600 times higher than the natural rate for that seismic activity.

“We can say statistically that it is very unlikely this activity represents a significant portion of natural seismicity,” Holland said. “We recognize there are naturally occurring earthquakes in Oklahoma, but they don’t represent what we are observing.”

The Oklahoma Corporation Commission has prioritized 347 wastewater disposal wells in seismically active areas, directing operators to prove their wells aren’t too close to basement rock. As of Monday afternoon, the agency had identified seven disposal wells in the area of interest to plug back; that is, to add more cement to the bottom of the wellbore and make it shallower. Several wells will be required to cut disposal volumes in half, OCC spokesman Matt Skinner said.

The tally on how many wells will be required to make changes could change, because the agency continues to analyze the information submitted, he said.

Skinner refused to comment on the OGS statement, because it had not yet been made public.

The Oklahoma Independent Petroleum Association’s chairman of environmental and regulatory affairs, Kim Hatfield, said operators need to cooperate by supplying the OGS and OCC with information requested. The industry trade group and operators have provided seismologic information and fault data to the OGS to help improve the agency’s fault map. Industry members have also provided disposal volumes and pressures to the OCC.

There should be a scientific basis to back any new changes for disposal well operations, Hatfield said. And issuing a blanket moratorium, even for wells in the Arbuckle formation in seismically active areas, won’t help the situation, Hatfield said. The industry needs to know how to continue with its disposal operations in a safe manner.

“This is an integral part of the business,” he said. “It has been done safely for 60 years and it will be done safely. We need to establish the conditions that permit us to do that.”

Holland said he and other seismologists need more information about rock permeability and the magnitude of stress rock formations can sustain.

Hatfield said he and others are trying to figure out the safest way to continue oil and gas operations, including disposing of wastewater. He said he suspects some people will call for a moratorium on all injection wells, regardless of potential implications for the industry.

“We have to decide what approach we’re taking,” he said. “Are we trying to solve a problem that permits the economic lifeblood of our state to continue, or are we going to take a hatchet to it?”

Holland and OGS research seismologist Amberlee Darold will present research on Oklahoma’s triggered earthquakes at the Seismological Society of America’s annual conference, which begins Tuesday in Pasadena, California.

According to research Darold will present, as much as 10 percent of Oklahoma earthquakes recorded between 2010 and mid-2012 can be linked to the hydraulic fracturing process. Those rates are higher than previously recognized in published scientific research, Holland said.

Holland said he and other seismologists need more information about rock permeability and the magnitude of stress rock formations can sustain.

Hatfield said he and others are trying to figure out the safest way to continue oil and gas operations, including disposing of wastewater. He said he suspects some people will call for a moratorium on all injection wells, regardless of potential implications for the industry.

“We have to decide what approach we’re taking,” he said. “Are we trying to solve a problem that permits the economic lifeblood of our state to continue, or are we going to take a hatchet to it?”

Holland and OGS research seismologist Amberlee Darold will present research on Oklahoma’s triggered earthquakes at the Seismological Society of America’s annual conference, which begins Tuesday in Pasadena, California.

According to research Darold will present, as much as 10 percent of Oklahoma earthquakes recorded between 2010 and mid-2012 can be linked to the hydraulic fracturing process. Those rates are higher than previously recognized in published scientific research, Holland said.

“Certainly the disposal wells are likely generating more seismicity than hydraulic fracturing,” he said.

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