Experts: Fracking-related earthquakes in the area are not likely
Professor of geology at California University of Pennsylvania Dr. Kyle C. Fredrick stops for a portrait in his geology classroom in the Eberly Science Building. Fredrick is an expert in groundwater hydrology. (Photo by Rebecca Devereaux)
This graphic by the U.S. Geological Survey shows the effects fluid injection and withdrawal can have on nearby faults.
Fracking can cause earthquakes in western Pennsylvania, but the seismic activity likely won’t be felt by people above ground, experts said.
That opinion is followed by a recent report from the state Department of Environmental Protection that found a low-level earthquake which occurred in Lawrence County by the Ohio border in April was related to fracking.
“There is a risk, but it is extremely low,” said Tim Carr, a professor of geology at West Virginia University.
The DEP said the five earthquakes that occurred just west of New Castle on April 25, 2016 were roughly 2 on the Richter scale, the equivalent of feeling a large truck drive by.
“When you put high- pressure fluids in the ground, it is going to impact what is underground,” said Kyle Fredrick, a geologist at California University of Pennsylvania.
“The idea that it is fracking makes it a touchy topic,” he said.
At the time the quakes were reported, Texas-based Hilcorp Energy Co. was using a technique called zipper fracturing, or hydraulic fracturing operations that are carried out at the same time on two horizontal wellbores that are parallel and adjacent to each other, the DEP said. The Hilcorp pad includes four wells.
When a site is fracked for natural gas, high pressure fluids are forced underground to crack oil and gas- bearing layers of rock. When cracked, those rock layers release pockets of oil or gas encased inside.
“Induced seismicity is a relatively new and complex technical issue,” DEP Acting Secretary Patrick McDonnell said in a statement. “The report reflects our commitment to understand what occurred, through extensive review with scientific and industry partners, and to formulate procedures to reduce seismic risk going forward.”
CUP’s Fredrick said the fracking-related earthquake is much different from the seismic activity that took place at well sites in Oklahoma last fall. In November, a 5.0 earthquake was reported, which caused renewed worries that oil and gas drilling was the cause.
What makes what has happened in Oklahoma much different from the earthquake in Lawrence County is that wastewater from fracking operations are pumped back into deep wells, the Washington Post said. In most cases, wastewater from fracking operations in Pennsylvania is taken out of state – usually Ohio – for disposal. Ohio has more disposal wells that the Commonwealth.
“I really don’t equate this with what has been going on in Oklahoma,” Fredrick said. “That is wastewater injection.”
The other thing to consider as well is the market for natural gas depressed. Despite the fact that Pennsylvania is the second-highest natural gas producing state in the country, revenue generated by wells in 2016 is expected to drop by 7 percent. Final numbers should be released in April, the state has said.
Plus, a DEP official notes that much of Fayette, Greene, Washington and Westmoreland counties sit in the Rome Trough, which is a long, fault-bounded geologic structure that has thickened over time.
“Over time, as sediments were deposited that eventually became the oil and gas reserves of the Appalachian basin, the depression allowed for thicker successions of material to accumulate ,” said Deborah Kenotic, DEP’s deputy communications director, in an email.
“The thickening has created a greater vertical separation between the Utica Shale and the crystalline basement rocks in Fayette, Washington, Westmoreland and Greene counties, thus reducing the likelihood of hydraulic communication and induced seismicity in those areas.”