How do drilling companies dispose of drilling wastewater? In Pennsylvania and other locations, drillers recycle much of the wastewater (or fracking fluid) by mixing it with new water and reusing it. Some drillers are recycling 100 percent of their wastewater. But in some areas, drillers use a method called injection wells—pumping the wastewater down deep wells created specifically for disposing of it—in a place where it will not rise back to the surface.
Injection wells are being used in another shale formation, the Fayetteville Shale, in Arkansas. And use of those wells has caused some controversy. Some believe injection wells in Arkansas have led to earthquakes in the area.
In Arkansas…two energy companies agreed March 4 to temporarily cease injection operations at the request of the Arkansas Oil and Gas Commission.
The commission said preliminary studies showed evidence potentially linking injection activities with nearly 1,000 quakes in the region over the past six months.
The Center for Earthquake Research and Information recorded around 100 earthquakes in the seven days preceding the shutdown earlier this month, including the largest quake to hit Arkansas in 35 years – a magnitude 4.7 on Feb. 27. A dozen of the quakes had magnitudes greater than 3.0.
In the days since the shutdown, there have been around 60 recorded quakes, with only one higher than a magnitude 3.0. The majority were between magnitudes 1.2 and 2.8, according to the center.*
One of the closed injection wells is owned by Chesapeake Energy, who maintains the practice of using injection wells is not causing the earthquakes.
"We remain confident that the facts and science will lead to a more constructive and satisfactory conclusion to this matter," said Danny Games, senior director of corporate development for Chesapeake’s Arkansas operations. "The science continues to point to naturally occurring seismicity, but to ensure that we provide the most complete expert analysis, we have agreed with the commission staff to keep our disposal well temporarily closed."*
We’ll keep an eye out as this story develops.
*The Intelligencer/Wheeling News-Register (Apr 3, 2011) – Proof Not There: Prof: Drilling, Earthquakes Not Connected