Hydraulic fracturing, not just wastewater injection wells, has likely caused small earthquakes in Oklahoma, a research scientist with the state said Wednesday. Austin Holland, speaking at the American Geophysical Union annual meeting in San Francisco, said his studies suggest that about 2 percent of the oil and gas wells hydraulically fractured in that state in the past 2 1/2 years were followed within 21 days by a quake within eight kilometers, or about five miles, of the well. While some likely were coincidental, not all were, concluded Holland, who is with the Oklahoma Geological Survey.
Holland’s finding of quakes triggered by hydraulic fracturing itself — the technique that pumps water, sand and chemicals at high pressure to fracture rock and release oil and gas — goes beyond the more common conclusion that high-volume injection wells are the most likely culprits of increased earthquakes in areas with oil and gas development. Injection wells continually pump fluid into deep formations below oil and gas-producing layers, while fracturing, or “fracking,” is a process that only lasts several days. Holland was one of three panelists at a session focused on the likelihood of earthquakes being induced by oil and gas activities.
Fellow panelists Art McGarr, of the Earthquake Science Center at the U.S. Geological Survey, and Cliff Frohlich, associate director of the Institute for Geophysics at the University of Texas at Austin, both said injection wells, rather than fracturing, can likely trigger quakes. McGarr noted that the size of quakes seem related to the volume of fluid injected, not how fast it was injected.
Ed Ireland, director of the Barnett Shale Energy Education Council, an industry group, said he hasn’t seen Holland’s research, but said “it’s interesting, because it would be contrary to everything that’s come along so far that I’m aware of.” Ireland said injection wells have garnered the most attention, “and even then it would have to be located directly over a fault.”
The Star-Telegram has a longer report here.
-- Jim Fuquay