Ohio Department of Natural Resources Director James Zehringer ordered operations halted at a fluid injection well near Youngstown on Dec. 30, 2011, after scientists from Columbia University's Lamont-Doherty Earth Observatory found a possible link to mild earthquakes.
Ohio has 177 Class 2 deep well injection sites. This was the first time seismic activity had been associated with one of them. ODNR said its seismic monitoring network detected 10 events within 2 miles of Northstar Disposal Services LLC's well during 2011. Each registered at 2.7 magnitude or lower on the Richter scale, well below the 4 points considered necessary to cause surface damage, it indicated.
Although the well operated by Northstar Disposal Services LLC was the only one in the vicinity taking fluid, ODNR has since ordered operations suspended at four others nearby as it analyzes data found by the Lamont-Doherty team, a spokeswoman said on Jan. 10.
"We still don't have a direct scientific link," she told OGJ. "We have a lot more data based on the epicenter, but we're continuing to study the area. We have enough information that we felt it was prudent to shut the wells down temporarily, and hope to have a comprehensive report available in another month."
Oil and gas producers have known for decades that injecting enough fluid into an underground formation might trigger tremors under the right conditions. Three US Geological Survey scientists—C.B. Raleigh, J.H. Healy, and J.D. Bredehoft—initially demonstrated this at various fluid pressures at Chevron Corp.'s Rangely, Colo., oil field in the early 1970s.
The problem is that it's impossible to predict, according to Terry Engelder, a professor at Penn State University's Geosciences Department who has done research on rock mechanics and structural geology. "Even if a volume of water triggers a 3.5 magnitude quake in one well, it may not in 15 others which are nearby," he explained.
Minor tremors
Engelder questioned attempts to link large water volumes required for hydraulic fracturing to possible earthquake activity because horizontal drilling spreads the fluid over a large area. Resulting tremors aren't significant, he said.
"It can't be overemphasized that these events are nondestructive," Engelder told OGJ. "In the industry, the technique for understanding a reservoir's distributed volume is to set up microseismic instruments and identify where such incidents take place."
During an interview on NPR's "All Things Considered" on Jan. 3, John Armbruster, who was part of the Lamont-Doherty team working in Ohio, said that underground fluid disposal without quakes is a matter of luck.
"I would advocate monitoring of wells to know when triggering of earthquakes first begins," he said. "Then you can decide whether to continue using that well."
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