As natural gas speculation increases in the Rogersville Shale in Eastern Kentucky, scientists are beginning research into the region’s existing seismic activity.
Right now, several test wells have been drilled into the Rogersville, which is thought to cover 4 million acres in Kentucky and West Virginia. The results of those test wells are confidential, but if the reserves prove profitable, companies could begin drilling large-scale oil and natural gas wells in the formation.
Tapping the Rogersville will also involve hydraulic fracturing, or fracking. Fracking is used to extract oil and gas from deep below the earth; the practice includes injecting water and chemicals miles underground. The dirty water is eventually discarded in deep disposal wells. In some oil and gas drilling areas, numerous earthquakes have been recorded, and scientists are becoming more confident that these quakes are linked to the industry.
Earthquake activity in Oklahoma in 2013 was 70 times greater than it was before 2008, state geologists reported. Oklahoma historically recorded an average of 1.5 quakes of magnitude 3 or greater each year. It is now seeing an average of 2.5 such quakes each day, according to geologists.
That’s why Kentucky seismologist Seth Carpenter said it’s important to establish a baseline for Kentucky’s seismic activity. The Kentucky Geological Survey has begun a project to measure small earthquakes—the kind that are usually undetected by people living nearby.
“As these oil and gas activities happen using unconventional methods—if they start to produce earthquakes for example—we would be able to see a change between how things were before these activities started and after the oil and gas activities started,” he said.
Fracking by definition causes seismic activity; it’s so slight it’s usually not detectable, Carpenter said.
But, in other states, problems have arisen when fluid migrated away from the fracking site and reacted with preexisting faults in the rock.
“One of the things we hope to be able to assess also is that even if we start to see earthquakes that are too small to be felt, might they lead to larger ones?” he said.
“Are the ingredients right in Eastern Kentucky for this to happen?"
He said he expects the monitoring network to begin measuring seismic activity this summer, and operate for at least a year.