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This new map of Earth’s stress field in the Permian Basin of West Texas and southeastern New Mexico could help energy companies avoid causing earthquakes associated with oil extraction. (Image credit: Jens-Erik Lund Snee)

Fracking, which involves pumping chemicals deep underground to unleash pockets of natural gas for collection, has been tied to increased seismic activity in places like Oklahoma. The small earthquakes have not caused significant damage or injuries, but they could lead to increased chances of major temblors to come, some scientists believe.

Now a Stanford team of researchers is trying to get ahead of a gas-and-oil boom in Texas. The Permian Basin and its 75,000 square miles of land is now the subject of a color-coded map showing the seismic risks, based on geophysical calculations, report the experts in the latest issue of The Leading Edge.

“We want to get out ahead of the problem in Texas,” said Mark Zoback, co-author of the study, a Stanford professor of geophysics. “We want to stop fluid injection from triggering even small earthquakes in Texas so that the probability of larger earthquakes is significantly reduced.”

Zoback and colleagues had previously published calculations that showed the injection of synthetic fluids into the ground accelerated earthquakes so that 6,000 years of activity was packed into approximately five years.

The new measurements of the faults and seismic stressors show a complicated region in the Permian Basin, between West Texas and the southeastern part of New Mexico.

The researchers found seismic activity in the Permian has already been on an increase when oil and gas harvesting increased in the 1960s, they write.

“We have collected hundreds of measurements of stress orientation and relative magnitude to identify potentially active normal, normal/strike-slip, or strike-slip faults that might be susceptible to earthquake triggering in this region,” the researchers write.

They found the Midland Basin and Central Basin Platform were both consistently stressed, and in an approximate east-west configuration.

However, the Delaware Basin shows a 150-degree clockwise rotation, complicating the map, and leading to regional variations of seismic risks.

Hence, the color-coded map.

“They can use these data every day in deciding the best direction to drill and how to carry out optimal hydraulic fracturing operations,” said Zoback.

“While the stress field in this region is surprisingly complex, the data is excellent and having documented what it is, we can now take action on this information and try to prevent the Permian Basin from becoming Oklahoma 2.0,” he added.

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