COLUMBUS, Ohio (AP) — A dozen earthquakes in northeastern Ohio were almost certainly induced by injection of gas-drilling wastewater into the earth, state regulators said Friday as they announced a series of tough new rules for drillers.
Among the new regulations: Well operators must submit more comprehensive geological data when requesting a drill site, and the chemical makeup of all drilling wastewater must be tracked electronically.
The state Department of Natural Resources announced the tough new brine injection regulations because of the report's findings on the well in Youngstown, which it said were based on "a number of coincidental circumstances."
For one, investigators said, the well began operations just three months ahead of the first quake.
They also noted that the seismic activity was clustered around the well bore, and reported that a fault has since been identified in the Precambrian basement rock where water was being injected.
"Geologists believe it is very difficult for all conditions to be met to induce seismic events," the report states. "In fact, all the evidence indicates that properly located ... injection wells will not cause earthquakes."
Northeastern Ohio and large parts of adjacent states sit atop the Utica and Marcellus Shale geological formations, which contain vast reserves of natural gas that energy companies are rushing to drill using a process known as hydraulic fracturing.
That process involves freeing the gas by injecting huge amounts of chemical-laced water, termed brine, into the earth, but that water needs to be disposed of when companies are done with it. Municipal water treatment plants aren't designed to remove some of the contaminants found in the wastewater, including radioactive elements. Deep injection is considered one of the safest methods for disposing of the wastewater.
Past earthquakes have been linked to energy exploration and production, including from injections of enormous amounts of drilling wastewater or injections of water for geothermal power, experts said.
They point to recent earthquakes in the magnitude 3 and 4 range — not big enough to cause much damage, but big enough to be felt — in Arkansas, Texas, California, England, Germany and Switzerland. And in the 1960s, two Denver quakes in the 5.0 range were traced to deep injection of wastewater.