Oklahoma Corporation Commission is continuing to shut down wells near the Cherokee and Medford areas after several earthquakes shook the area in late November.
“The Commission’s Oil and Gas Conservation Division (OGCD) is expanding its efforts to reduce the risk of earthquakes potentially triggered by saltwater disposal wells,” according to a bulletin from Tim Baker, OGCD director.
The bulletin states OGCD has reviewed earthquake activity magnitude 2.5 and greater within two miles of the zones of interest.
“As part of a joint effort to decrease the risk of induced seismicity, you will need to complete reduction of disposal volumes in accordance with the following schedule and as indicated for the wells below,” according to the bulletin. “All disposal well volumes shall be calculated on a daily basis.”
The commission is directing four disposal wells within three miles of earthquake activity in the Byron and Cherokee area to stop operations.
Another 47 wells further from the activity are requested to cut disposal volumes of 25 to 50 percent.
Disposal wells 10 to 15 miles from the earthquake activity in Cherokee are being placed on notice for possible operation changes.
According to a release from the commission, the net volume reduction is 47 percent. The provisions are known as the Byron/Cherokee Plan, according to the release.
Three wells in the Medford area, within three miles of the activity, are requested to halt operations.
Another 19 wells further from the activity will cut disposed volume of 25 to 50 percent.
The total net volume reduction is 42 percent, according to the commission’s release.
Wells within 10 to 15 miles of the Medford earthquake activity are being place on notice for possible operation changes. That impacts about 39 wells, according to the release.
Sandridge Exploration and Production owns the wells advised to shut down in both plans.
OCC will be requiring gauges and flow meters to be placed on wells tasked with volume reduction. Gauges must be placed on wells by Dec. 11.
The response comes after a 4.7 magnitude temblor was recorded in Alfalfa County on Nov. 19, according to U.S. Geological Survey. It was centered at Carmen, 8 miles southwest of Cherokee and 36 miles west-northwest of Enid, and was 4 miles deep.
On Nov. 30, another 4.7 temblor shook the area. The epicenter was 16 miles west, southwest of Medford, 24 miles northwest of Enid and 51 miles west of Ponca City. It was 3.2 miles deep.
This year, 750 earthquakes magnitude 3.0 or greater, including 26 measuring magnitude 4.0 or greater, have been recorded in the state. In 2014, there were 585 quakes magnitude of 3.0 or greater, including 15 measuring magnitude 4.0 or greater.