Barnett Shale

Fracturing can cause small quakes, Oklahoma researcher says

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

New research suggests fracking can cause small earthquakes

At least since small earthquakes were recorded near wastewater injection wells at Dallas/Fort Worth Airport and in Johnson County, there hasn't been much argument that the wells are capable of causing tremors when fluid gets into existing faults deep underground. But, the thinking went, that's not the same as hydraulic fracturing itself causing quakes. Now comes a report from Canada that draws direct links from fracking itself and earthquakes. Smithsonian.com has a report here, which includes a link to the study by the British Columbia Oil & Gas Commission.

-- Jim Fuquay

UT study links some disposal wells to small earthquakes

Another study, this one at the University of Texas at Austin, says small earthquakes appear to be associated with some high-volume wastewater disposal wells, but not all of them. Using seismographs placed around the Barnett Shale, the study by Cliff Frohlich at UT's Institute for Geophysics also found many more small quakes than previously reported, suggesting the phenomenon is more common than supposed. The UT report echos a similar report by the National Research Council in June that also linked seismic activity with high-volume injection wells. Frohlich found that quakes occurred near nine of 27 high-volume disposal wells he studied in Johnson County, while there were few quakes near similar wells in Wise County. "A plausible hypothesis to explain these observations is that injection only triggers earthquakes if injected fluids reach and relieve friction on a suitably oriented, nearby fault that is experiencing regional tectonic stress," Frohlich wrote, adding that the theory would need more study to be proved. The Star-Telegram's report is here.

-- Jim Fuquay

New USGS study ties petroleum production and small earthquakes

The U.S. Geological Survey is the latest to weigh in on the issue of earthquakes and their tie to oil and gas production, saying an increase in small quakes is "almost certainly man-made." Here's the Associated Press story.

-- Jim Fuquay