WHEELING - A West Virginia University professor has joinedChesapeake Energy officials in disputing a notion that natural gasdrilling activity contributes to earthquakes, despite officials inArkansas making such a connection.
The number and magnitude of earthquakes in central Arkansas havedeclined noticeably since Chesapeake and another company shut downtwo of its underground injection wells in the area last month,Arkansas officials said.
"We have definitely noticed a reduction in the number ofearthquakes, especially the larger ones," said Scott Ausbrooks,geohazards supervisor for the Arkansas Geological Survey. "It'sdefinitely worth noting."
The two Arkansas injection wells are used to dispose ofwastewater from gas drilling and fracking. One is owned byChesapeake and the other by Clarita Operating. The two injectionwells at issue dispose of the frack water when it can no longer bere-used by injecting it into the ground.
Similar injection wells are located in West Virginia, and atleast one currently is being drilled in Belmont County.
Tim Carr, WVU's Marshall Miller Professor of Energy, said thereis no evidence that fracking or fluid injection into undergroundwells leads to earthquakes.
In noting the action does cause some "micro-seismic" shifting,Carr said, "These are much, much less than having a large truck goby. They are measured with sophisticated downhole tools and are usedto map fracture stimulation treatments. No one could ever feel oreven detect these events at the surface.
"In terms of inducing earthquakes, fracture stimulation(fracking) would rate very low to non-existent on my list ofconcerns."
In April 2010, a 3.4 magnitude earthquake hit Braxton County,W.Va. In a span of several months, the area was hit by five moresuch quakes. The quakes were small - about a 2.7 magnitude - butlarge enough to catch the attention of state officials.
Carr attributes the West Virginia tremors to natural activity.
"The earth does move and shake, as evidenced by recent events inJapan. Earthquakes in West Virginia are known from throughouthistory," he said.
In Arkansas, the two energy companies agreed March 4 to ceaseinjection operations temporarily at the request of the Arkansas Oiland Gas Commission. Chesapeake officials have said they do notbelieve there is a connection between the injection wells and thearea's seismic activity.
The commission said preliminary studies showed evidencepotentially linking injection activities with nearly 1,000 quakes inthe region over the past six months.
A six-month moratorium on new injection wells in the area tookeffect in January to allow time to determine what relationship, ifany, there is between the wells and the earthquakes.
"We remain confident that the facts and science will lead to amore constructive and satisfactory conclusion to this matter," saidDanny Games, senior director of corporate development forChesapeake's Arkansas operations. "The science continues to point tonaturally occurring seismicity, but to ensure that we provide themost complete expert analysis, we have agreed with the commissionstaff to keep our disposal well temporarily closed."
The Center for Earthquake Research and Information recordedaround 100 earthquakes in the seven days preceding the shutdownearlier this month, including the largest quake to hit Arkansas in35 years - a magnitude 4.7 on Feb. 27. A dozen of the quakes hadmagnitudes greater than 3.0.
In the days since the shutdown, there have been around 60recorded quakes, with only one higher than a magnitude 3.0. Themajority of the quakes were between magnitudes 1.2 and 2.8,according to the center.
Similar to the Marcellus shale underlying West Virginia and partsof Ohio, the Fayetteville shale is a major source of natural gas inArkansas.
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