By Paul Monies

The Oklahoma Corporation Commission said Monday it has asked operators of five nearby saltwater disposal wells to reduce volumes after a swarm of earthquakes hit the Edmond area in the past week.

Central Oklahoma residents have been shaken by a spate of earthquakes, including a 4.3-magnitude quake Dec. 29 and a 4.2-magnitude on New Year's Day. In all, 14 earthquakes greater than 2.5-magnitude have been reported in the Edmond area in the past week, according to the United States Geological Survey.

The latest action marks a continuation of the Corporation Commission's strategy of targeting targeting saltwater disposal wells in the deep Arbuckle formation. Researchers have linked high-volume disposal of the produced water that comes up with oil and natural gas to the state's ongoing escalation of man-made earthquakes.

The commission said there are five operating Arbuckle disposal wells within 10 miles of the recent Edmond earthquake activity. Disposal wells within 3.5 miles will be directed to reduce disposal volumes 50 percent, while the others are to cut volumes by 25 percent. All Arbuckle disposal wells within 15 miles are expected to test reservoir pressures.

The Corporation Commission said Devon Energy Corp.'s Harvey 1-11 saltwater disposal well and Pedestal Oil Co. Inc.'s C.J. Judy disposal well have agreed to suspend operations to aid in the research effort. In all, the commission said operators of 18 disposal wells were contacted for some type of action related to the latest earthquake activity.

"We are working with researchers on the entire area of the state involved in the latest seismic activity to plot out where we should go from here," said Tim Baker, director of the commission's Oil and Gas Conservation Division. "We are looking not only at the Edmond area, but the surrounding area as well, including the new seismic activity that has occurred in the Stillwater area."

Three earthquakes greater than 3.0-magnitude were recorded in the Stillwater area on Monday, according to the USGS.

None of the Edmond-area disposal wells targeted by regulators on Monday are operated by SandRidge Energy Inc., which is defying a voluntary directive issued last month to reduce volumes at six disposal wells in Alfalfa County. Commission officials are preparing an administrative case against the company.

Seismologist Daniel McNamara, with the USGS Geologic Hazards Science Center in Golden, Colo., said last week the recent Edmond earthquakes may have revealed a previously unknown fault line. The fault runs northeast at least two miles from near Interstate 35 and Second Street.

McNamara said it was unknown if it could connect to other, larger faults such as the Nemaha Ridge or the Wizetta Fault, the fault involved in the 5.6-magnitude earthquake that hit the Prague area in 2011.

Oklahoma had 881 earthquakes greater than 3.0-magnitude in 2015, according to the OGS. That was up 50 percent from the 585 recorded in that category in 2014.

The state had 29 earthquakes greater than 4.0-magnitude in 2015, up from 14 in 2014, OGS records show.

So far in 2016, there have been eight earthquakes greater than 3.0-magnitude in Oklahoma. according to USGS.

(c)2016 The Oklahoman