Injection wells, earthquakes: related?

On January 24, 2012 — No comments

A handful of low magnitude earthquakes recorded in Ohio was enough to shut down five wastewater injection wells used to dispose of brine and other byproducts of the natural gas drilling process.

One — a 4.0 earthquake outside of Youngstown, Ohio, on New Year’s Eve — was felt as far north as Toronto. Some experts link the deep injection to the quakes, but others are not ready to put the full responsibility on activity related to increased gas drilling.

However, the Ohio earthquakes are not an oddity. Injection wells also have been suspected in earthquakes in Arkansas, Colorado and Oklahoma.

So with more than 3,000 natural gas wells and more than 200 injection wells drilled in northwest Louisiana since the onset of the Haynesville Shale, why hasn’t the earth in northwest Louisiana been shaking?

The answer is a matter of simple geology. Under feet here is soft rock, instead of harder formations in the Northern states. Louisiana’s sands give the ground flexibility that would move as underground compression or tension builds up.

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