Wednesday, February 09, 2011

TOP STORY >> Earthquakes from drilling feared

Leader staff writer

Those who drive the state highways through White, Cleburne, Faulkner and Van Buren counties where large companies are drilling for gas in the Fayetteville shale formation have seen both the benefits and damage caused by the gas drilling.

The roads are torn up from heavy loads of drilling equipment and water that is used to break up the shale to extract gas, but the homes along those roads show that their owners, who are paid a share of the profits for the gas under their land, are a little more prosperous than they once were.

It is clear that the gas boom has benefited some while it has only been a nuisance to others.

What isn’t at all clear is whether the earthquakes around Guy in Faulkner County, which are a concern to experts and residents alike, are connected to the gas industry.

Dr. Haydar Al-Shukri, head of the Arkansas Center for Earthquake Education and Technology Transfer at UALR, said although the earthquakes are not directly connected to the drilling, they could be connected to the disposal of the wastewater from the drilling.

The pattern of earthquakes at Guy over the past several months is exactly like the small earthquakes seen around the world where wastewater from the drilling process is injected under high pressure into miles-deep wells. But they also are like the earthquakes in the early 1980s a few miles away at Enola, decades before the drilling started.

“We need to be very clear before we make a correlation,” he said.

Since the companies won’t stop injecting the wastewater to see if the earthquakes stop, all the experts can do is watch both and look for the connection between the earthquakes and the activity at the injection wells.

Shurki said it has been proven that injecting fluids deep into the Earth under high pressure will induce seismic activity.

But it has not been proven yet whether the earthquakes at Guy were induced or naturally occurring.

The maximum earthquake expected from high-pressure injection of wastewater into deep wells is a magnitude 4.5, Shurki said.

The largest one recorded at Guy has been a magnitude 4.

Experts first noticed a connection between earthquakes and injection wells about 50 years ago when the Army was injecting wells near the Rocky Mountain Arsenal.

Hundreds of quakes were recorded in the area and scientists began studying what they call “induced seismicity.”

Stations to measure potential activity at two new wells at Guy were set up last summer, and in September the earthquakes started.

The largest, the magnitude 4, was recorded in October, but December saw at magnitude 3.1.

In all, there have been 640 measurable quakes since September, a number comparable to the earthquakes a few miles away at Enola in 1982.

Enola also experienced a series of earthquakes in 2001, which was also before the gas drilling started.

Guy and Enola are not in the New Madrid Seismic Zone, where a magnitude 7.0 earthquake in December 1811 and others that followed in early 1812 are reputed to be the most powerful to hit the eastern U.S., felt over an estimated 50,000 square miles.