The Oklahoma Corporation Commission’s (OCC) Oil and Gas Conservation Division (OGCD) has issued new directives to disposal well operators in Oklahoma as part of the continuing evolution of the agency’s induced seismicity traffic light system.
Under the new directives, disposal well operators in areas of interest that inject into the Arbuckle formation had until April 18 to prove to the OGCD that the disposal well is not disposing below the Arbuckle formation. The OCC said that there is broad agreement among seismologists that disposal below the Arbuckle poses a potential risk of causing earthquakes, as it puts the well in communication with the solid basement rock.
Operators who could not show that the well is not disposing below the Arbuckle and who do not have an approved plugging plan will be required to reduce their disposal volume by 50%.
The directive applies to 347 of the approximately 900 Arbuckle disposal wells in Oklahoma.
In addition, the OCC redefined the term area of interest to include seismic swarms.
According to the OCC, a swarm is an area consisting of at least two events with epicenters within a quarter mile of one another, with at least one event with a magnitude 3.0 or higher. An area of interest is an approximately six-mile area with the central mass of the swarm serving as the area center.
Previously, an approximately six-mile circle around a 4.0 magnitude earthquake constituted an area of interest. The OCC said that the change is expected to more than double the number of disposal wells within an area of interest.
The OCC established the traffic light system in 2013. Other elements of the traffic light system include:
- The yellow light permitting program that requires seismicity review for any proposed disposal well and requires special permitting based on seismicity concerns for any well:
- proposed within three miles of a stressed fault, even in the absence of seismicity
- proposed within approximately six miles of an earthquake swarm or magnitude 4.0 event
- Rules increasing from monthly to daily the required recording of well pressure and volume from all Arbuckle wells in the state
- Rules requiring mechanical integrity tests for wells disposing of volumes of
- 20,000 barrels per day or more have increased from once every five years to every year, or more often if so directed by the OCC
- Full review of disposal well operations in an area of interest