Regulators with the Oklahoma Corporation Commission (OCC) said the operators of three oil and gas wastewater disposal wells near a town in Logan County stricken by increased seismic activity have agreed to change their operations.
On Tuesday, the OCC's Oil and Gas Conservation Division (OGCD) said the operators of two of the wells near Crescent, OK, had agreed to shut down their operations, while the operator of a third well located the farthest from the seismic activity had agreed to reduce injected volumes by 50%.
The OGCD said the unidentified operators took the actions voluntarily and no directives were necessary.
Last March, the OGCD issued a directive to operators of 347 disposal wells targeting the Arbuckle formation to prove that they are not injecting oil and gas waste into basement rock below it. The directive was expanded to include an additional 211 disposal wells earlier this month. The wells are all within "areas of interest," which include 21 of the state's 77 counties that have seen increased seismicity (see Shale Daily, July 20; April 2).
In April, scientists with the Oklahoma Geological Survey (OGS) reported that the state is currently being hit by earthquakes at a rate about 600 times greater than historic background data (see Shale Daily, April 22). Seismicity increased from an average of one-and-a-half earthquakes of 3.0 magnitude or greater to about two-and-a-half such earthquakes every day in 2014.
According to the OGS, the earthquakes are primarily occurring within the crystalline basement. The majority of the state's approximately 900 injection wells target the Arbuckle formation, which closely overlies the crystalline basement.
Last fall, Oklahoma regulators shut in a disposal well that was thought to have been drilled too deep following a spate of seismic activity in the area (see Shale Daily, Oct. 31, 2014).