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W.Va. studying link between quakes, disposal wells

Sep. 01, 2010 @ 06:50 AM

FRAMETOWN, W.Va. — Eight small earthquakes in central West Virginia since April have Chesapeake Energy and the state Department of Environmental Protection discussing the possibility of seismic monitoring near a disposal well for gas-drilling fluids.

Oklahoma-based Chesapeake has injected more than 10.6 million gallons of brine and hydraulic fracturing fluid into the well since March 2009. The underground injection site in the Frametown area has been a permitted disposal well since 2008.

Some geologists suspect high pressure and wastewater have lubricated old fault lines, allowing them to slip and trigger small earthquakes. Chesapeake isn't so sure, but it has agreed to reduce the volume of fluid it's injecting.

Gene Smith, compliance manager for the DEP, said no link has been proven, and no seismic events have been reported at 70 similar disposal wells around West Virginia. Still, he said, the state will investigate.

"We're looking at the mechanics of the well, the geology of the area and the events that have been happening in the area, to see, from a scientific level, if what's taking place could cause earthquakes," Smith said.

Since April 4, Braxton County has been shaken by eight small earthquakes registering between 2.2 and 3.4 on the Richter scale. No major damage was reported.

Drilling companies are producing wastewater as they rush to tap the Marcellus shale field, a rich natural gas reserve that underlies Ohio, West Virginia, Pennsylvania and New York. The gas is locked in tightly compacted rock a mile underground, and freeing it requires unconventional horizontal drilling technologies and vast amounts of water.

The DEP says many companies are recycling much of their water, but some is also pumped back into storage wells.

Marshall University geology professor Ronald Martino said it's "quite possible" the quakes are linked to the high-pressure injection of those fluids.

Geologists have known of a possible link between fluid injection and small quakes for a half-century, he said, and the potential impact on fault lines under Braxton County should be explored further.

Chesapeake spokeswoman Maribeth Anderson said "natural seismicity has long been observed in this part of Appalachia," and seismic activity often occurs in clusters.

But Martin Chapman, director of the Virginia Tech Seismic Observatory, said earthquakes are fairly rare in the center of West Virginia.

The U.S. Geological Survey said the strongest earthquake in West Virginia was in November 1969, when a magnitude 4.3 quake struck Mercer County.

The Braxton County quakes "could happen naturally, but probably not so many, so close together," Chapman said. "... Something's going on there, and I have a strong suspicion that it's something associated with drilling."

Michael Hohn, director of the West Virginia Geological and Economic Survey, agreed that when earthquakes are clustered, "it's time to pay attention."

A study released in March cited underground injection at a Chesapeake disposal well in Texas as a plausible cause for a series of small earthquakes near Grand Prairie and Irving.

The first quakes occurred in October 2008, and 11 more that were too small to be felt occurred over the next several months, according to the study by the University of Texas and Southern Methodist University.

The quakes occurred about a third of a mile from a disposal well, and the study said none has been reported since the well shut down last fall.

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