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Yet another twist to the fraccing debate

IN WHAT appears to certainly provide more fodder to the anti-fraccing brigade, there is research suggesting a direct co-relation between the devastating earthquake in Japan in 2011 and subsequent tremors in the oil fields of West Texas. <b>By Gomati Jagadeesan.</b>

Staff Reporter
Yet another twist to the fraccing debate

A study in the prestigious journal Science claims oil and gas drilling operations, especially wastewater reinjection could make fault zones sensitive to shock waves from distant quakes of high magnitude.

While it is known that large quakes can trigger tremors in faraway zones that are volcanically active, the study provides clues to the influence of remote quakes on fault lines that have been eroded by oil field activities such as deep disposal of wastewater.

The study from Columbia University’s Doherty Earth Observatory notes that a surge in US energy production in the past decade or so has sparked a rise in small to mid-sized earthquakes in the US.

“Large earthquakes from distant parts of the globe are setting off tremors around waste-fluid injection wells in the central United States,” the study says.

“Furthermore, such triggering of minor quakes by distant events could be precursors to larger events at sites where pressure from waste injection has pushed faults close to failure.”

Among the sites studied by the researchers are a set of injection wells near Prague, Oklahoma. There, the study says, a huge earthquake in Chile on February 27 2010 triggered a mid-sized earthquake less than a day later.

There were subsequent tremors recorded in the following months, culminating in probably the largest quake yet associated with waste injection – a magnitude 5.7 event that happened in Prague on November 6 2011.

Earthquakes in Japan in 2011 and in Sumatra the following year also set off mid-size tremors around injection wells in western Texas and southern Colorado, the study says.

“The fluids are driving the faults to their tipping point,” lead author Nicholas van der Elst said.

“The remote triggering by big earthquakes is an indication the area is critically stressed.”

Even as the fraccing debate rages, the study may be the first to find evidence of earthquakes triggered on faults that are critically stressed by wastewater injection.

Admittedly, the research is still in its infancy and requires further refining. Experts say that if the study’s methodology can be replicated and extended to other sites, it can help understand the stress zones.

For the US energy sector, which has engulfed by the shale gale, the study’s initial observations at least pose a huge problem.

While studies have demonstrated that hydraulic fracturing itself is only very rarely the direct cause of felt earthquakes, wastewater from fraccing could become a huge issue.

Indeed, many point out the regulatory framework for wastewater disposal wells is largely designed to protect drinking water sources from contamination and does not address earthquake safety issues.

With the study providing some links, the industry practices could be up for more regulatory oversight.

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