GAS DRILLING SHAKES EARTH UP

Study: Dallas-area quakes likely tied to gas drilling
Mike Lee, March 10, 2010 (Ft. Worth Star-Telegram via Houston Chronicle)

"A team of university researchers has concluded there's likely a link between a series of small earthquakes at Dallas/Fort Worth Airport and an injection well used to get rid of wastewater from natural gas drilling.

"Chesapeake Energy, which owns the injection well in question, disputed that conclusion. Researcher Brian Stump of SMU, one of four researchers who published [Dallas-Fort Worth earthquakes coincident with activity associated with natural gas production], said that the injection well at the airport was a ‘plausible cause’ of the earthquakes. The quakes started seven weeks after the well began operating in 2008 and stopped when the well was closed."

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"The researchers couldn't draw a conclusion about earthquakes that were felt further south, in the Johnson County city of Cleburne, around the same time; research there is ongoing. Stump said more research is vital…

"Chesapeake Energy signed a lease to drill for gas at the 18,000-acre airport in 2006 and drilled two injection wells to get rid of wastewater from the gas wells [and contends there is not conclusive proof of a direct causal link between the drilling and the quakes]…Each natural gas well produces millions of gallons of wastewater that can be contaminated with salt, chemicals and crude oil. Injection wells dispose of the waste by forcing it deep into the ground under high pressure."

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"The earthquakes weren't big enough to do any damage on the surface; the biggest was magnitude 3.3. SMU researchers began investigating in 2009 and were joined by researchers from the University of Texas.

"Researchers discovered that the earthquakes were centered around a fault line that ran close to the injection well at the south end of the airport, Stump said. Also, they occurred at the same depth as the injection well, roughly 4.4 to 4.8 kilometers…[T]he researchers theorized that the pressure from fluid, or possibly heat from the process, could have been a trigger for the earthquakes. Or the fluid could have served as a lubricant and caused the existing fault line to slip, Stump said."