An injection well operated by SandRidge Energy shut down Tuesday because of continuing earthquakes in Alfalfa County, OK, near the Kansas border, Oklahoma state officials said.
The well is the second active wastewater injection well directed to “shut in” or halt operations by the Oklahoma Corporation Commission since it began a new monitoring system in 2013.
Agency staff issued the directive Tuesday morning because of a magnitude-4.1 earthquake recorded in the area Friday, said Matt Skinner, a spokesman for the commission. The well is just west of the Alfalfa County town of Cherokee.
“They were operating under a ‘yellow light’ permit with language that said shut in if there’s any seismic activity,” Skinner said.
Injection wells dispose of wastewater, laden with salt and toxic chemicals, produced from oil and gas wells in a fracking environment. The state has about 3,200 active injection wells that disposed of a combined 1.1 billion barrels of wastewater in 2013.
Due to a huge increase in earthquakes in recent years, the Corporation Commission began using a “traffic light” system in December 2013.
Under the system, wells within a six-mile radius of a magnitude-4.0 earthquake end up placed under operating restrictions. If additional earthquakes occur within six miles of an active well in that area, the commission can order the operator to halt injection while they gather more information.
Dozens of scientific studies since the 1970s, including several studies of Oklahoma earthquakes, linked injection wells and earthquakes. Scientists at the U.S. Geological Survey have also said they believe the state’s increased seismicity is due to injection wells.
“We received a notice from the Corporation Commission that under their new monitoring review for saltwater disposal wells, this review process is underway,” said Jeff Wilson, vice president for government and public affairs at SandRidge. “As we have in the past, and as we continue to do with all Corporation Commission requests, we are working closely with commission staff to provide them any and all information needed.”
A consultant for SandRidge, J.P. Dick, testified during a hearing the company planned to drill numerous horizontal wells in the region, known as the Mississippian.
With the advent of horizontal drilling combined with fracking — or hydraulic fracturing of subsurface rock — the area in north-central Oklahoma and across the border in Kansas has seen a boom in oil drilling. Because of heavy water content in the area, operators there want disposal wells close to drilling operations.
“The cost of water disposal is a significant part of developing the Mississippian common source of supply, and trucking the water to a commercial disposal facility is cost prohibitive,” Dick told the commission.
“Absent the ability to dispose of the water, … the development of the Mississippian common source of supply will cease. Applicant has expended a significant amount of time and money.”
Dick told the commission he had examined well logs for the area and “determined that there is no faulting in the immediate area.” He said “the recent seismic activity in this area appears to be naturally occurring” and the injection well’s operation would not trigger earthquakes in the area.
The well and many others in the state inject into the Arbuckle geologic formation, a porous layer of rock just above the granite “basement” layer. That layer is prone to fracturing and faults, so the commission requires tests to ensure that wells don’t penetrate the basement rock.
Records show that commission staff also issued a directive to halt injection at a Payne County well operated by Devon Energy on Nov. 10 due to continuing earthquakes in that area. The well could dispose of 25,000 barrels per day following a hearing in September.
A spokesman for Devon declined to comment on the matter.