LITTLE ROCK, Ark. -- Two natural gas exploration companies have agreed to extend the shutdowns of two injection wells in Arkansas as researchers study whether the operations are linked to more than 1,000 unexplained earthquakes in the region, a state commission said Wednesday.
Chesapeake Energy Corp. and Clarita Operating LLC asked to postpone a scheduled April 26 hearing on the shutdowns until the Arkansas Oil and Gas Commission's next meeting on May 24, said Shane Khoury, deputy director and general counsel for the commission.
Khoury said the commission agreed to the continuance provided the companies not restart injection well operations at the two wells, both located in Faulkner County, before the May hearing.
"It was fine with us," Khoury said. "Our goal was to request a 60-day continuance of the shutdown at that meeting anyway. The more time we have, the more confident we will be with results of study."
BHP Billiton acquired the well from Chesapeake on March 31, but Khoury said the transfer request has not yet been received, so the commission recognizes Chesapeake as the owner.
It was the second time the owners of the two wells have filed for a continuance, with the first occurring before the March 29 hearing. The wells are used to dispose of waste fluid from natural gas production.
Clarita and Chesapeake agreed March 4 to temporarily cease injection operations at the request of the commission so scientists could analyze whether injection well operations were possibly causing the tremors.
The commission has said preliminary studies showed evidence potentially linking injection activities with more than 1,000 quakes in the north-central cities of Greenbrier and Guy since September, including the largest quake to hit the state in 35 years – a magnitude 4.7 on Feb. 27.
Kris Sava, BHP Billiton spokesperson, said in a written statement that the company's goal is "to develop the Fayetteville shale in line with our values of ensuring we fully protect people, the environment and communities where we operate."
"We will use the coming months to review the available data, and speak with interested stakeholders to understand the facts about the operating history of the well and the recent seismic activity in Faulkner County," Sava said.
Scott Ausbrooks, a geo-hazards supervisor for the Arkansas Geological Survey, said the area's seismic activity has dramatically declined since the injection well closures.
"We're still having earthquakes, but that's not unexpected," he said. "We've definitely seen a marked decrease in the number of earthquakes since the shutdown, especially the larger ones."
He said that in the month before the shutdown, there were more than 80 seismic events with a magnitude 2.5 or greater, compared with 20 in the month after.
The largest quake before the well closures was the magnitude 4.7 in February, while the largest since the closures were the two quakes in early April with magnitudes 3.9.
Ausbrooks said it's too soon to say if the quakes are directly related to the injection well operations, but that scientists are ready to show their research to the commission.
"We would have been ready two months ago to present our findings, but more time is fine. We can see if the trend continues," he said.
The Fayetteville Shale, an organically-rich rock formation underlying the region, is a major source of natural gas in Arkansas. Drillers free up the gas by using hydraulic fracturing or "fracking," which requires injecting pressurized water to create fractures deep in the ground. The two injection wells at issue dispose of "frack" water when it can no longer be re-used by injecting it into the ground.