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Study links quakes with injection wells

A study links the increase in earthquakes in the Central and Eastern United States to fluid injection wells used in oil and gas development.

The study, by the University of Colorado-Boulder and the U.S. Geological Survey, includes earthquakes observed in the Trinidad area in 2011.

The largest earthquake in the Trinidad area was recorded as 5.3-magnitude on Aug. 22, 2011, near the site of quakes recorded in 2001. There was concern after the 2001 quake that nearby coalbed methane operations could have triggered it, but there had been earlier quakes in the area in 1966, 1973, 1983 and 1996. Nearby quakes have been reported frequently along known faults in the area.

The Raton Basin contains coal seams that are being explored for coalbed methane and many quakes in recent years have generated some speculation about whether drilling was a cause. Studies by the Colorado Geological Survey and the USGS after the 2011 Trinidad earthquake were inconclusive about whether injection wells were a factor. In 2001, the quakes stopped although injection continued.

Nationally, there were only a handful of earthquakes associated with nearby mining or drilling sites in the 1970s, with an increase to 650 in 2014, according to Matthew Weingarten, who led the CU-USGS study.

Related: Broad approach needed to pinpoint earthquake causes

“This is the first study to look at correlations between injection wells and earthquakes on a broad, nearly national scale,” said Weingarten of CU-Boulder’s geological sciences department. “We saw an enormous increase in earthquakes associated with these high-rate injection wells, especially since 2009, and we think the evidence is convincing that the earthquakes we are seeing near injection sites are induced by oil and gas activity.”

A paper on the study appears in the June 18 issue of Science.

High-rate injection wells, those which pump more than 300,000 barrels of oil into the ground per month, are more likely than other wells to be associated with earthquakes, the researchers found. They looked at a database of 180,000 injection wells and found more than 18,000 were associated with earthquakes.

In Colorado, the areas most affected by earthquakes associated with injection wells were the Raton Basin in the southern part of the state and near Greeley.

“People can’t control the geology of a region or the scale of seismic stress,” Weingarten said. “But managing rates of fluid injection may help decrease the likelihood of induced earthquakes in the future.”

 

This article was written by Chris Woodka from The Pueblo Chieftain, Colo. and was legally licensed through the NewsCred publisher network.