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Petroleum geologist to present new evidence on human-induced earthquakes

A petroleum geologist who served on a committee studying how, when and where fluid injected underground can cause earthquakes will speak today on recent revelations about hydraulic fracturing and underground wastewater injections.

Donald Clarke, a California-based petroleum geology consultant and professor at University of Southern California will deliver a talk titled, “Hydraulic Fracturing and Earthquakes: How Do We Move Forward and Do the Right Thing?” at 7 p.m. today at Keystone College.

“There are some absolutely new and breaking things,” Mr. Clarke said.

Mr. Clarke served on a National Research Council committee studying the connection between “induced seismicity,” or man-made earthquakes, and geothermal energy, oil and gas production, wastewater injection and carbon capture and storage.

The committee released a report almost two years ago stating hydraulic fracturing does not pose a high risk for earthquakes because the technique, compared to the others, injects a fluid over a short period of time and maintains a closer balance between fluid injected and removed than some of the other techniques.

Wastewater injection wells, one of the most common methods of hydraulic fracturing wastewater disposal, poses “some risk,” because of the potential for larger volumes intended for permanent storage to increase the pore pressure of the rock, the report states.

At the time, only one seismic event from hydraulic fracturing and eight from wastewater injection were scientifically confirmed in the United States. Since then, new data have emerged linking these techniques to earthquakes, Mr. Clarke said.

One example Mr. Clarke pointed out is a set of earthquakes from 2009 to 2011 in the Horn River Basin in British Columbia, which the British Columbia Oil and Gas Commission linked to hydraulic fracturing near existing faults. The commission released a report on the earthquakes in the August 2012, two months after the National Research Council committee’s report.

Since the NRC report, scientists have linked more earthquakes to wastewater injection near Youngstown, Ohio, and Prague, Okla., Mr. Clarke said.

The brittleness of the rock, the presence of an existing fault line, the porosity and permeability of the rock and presence of stress fields above are all factors in causing induced seismicity, Mr. Clarke said.

“It’s a little bit complex, so that’s why our recommendation is to develop computer models and gather more data,” he said.

Pennsylvania only has eight active wastewater injection wells, mostly in western Pennsylvania, according to a database the U.S. Environmental Protection Agency shared with The Times-Tribune. The state has not experienced any earthquakes that have been linked to hydraulic fracturing or wastewater injection.

From 2000 through 2014, Pennsylvania experienced about 100 observed earthquakes, according to documents shared by Penn State seismologist Eliza Richardson, Ph.D. Most of these occurred in a cluster in the center of the state, with other, smaller clusters to the southeast. Almost all of these were magnitude 3 or under.

Contact the writer: bgibbons@timesshamrock.com, @bgibbonsTT on Twitter

To see the National Research Council committee’s study, visit http://i2.cdn.turner.com/cnn/2012/images/06/15/induced.seismicity.prepublication.pdf

To see the British Columbia Oil and Gas Commission’s report, visit http://www.bcogc.ca/node/8046/downloadIf you go

–Who: Donald Clarke, Ph.D., petroleum geologist and University of Southern California professor

–What: “Hydraulic Fracturing and Earthquakes: How Do We Move Forward and Do the Right Thing?”

–When: 7 p.m. today

–Where: President’s Dining Room, Hibbard Campus Center, Keystone College, La Plume Twp.

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