Regulators in Oklahoma have issued new restrictions on underground injection control wells in the vicinity of the Arbuckle formation – a 122 square mile area that recently experienced a cluster of minor earthquake activity, citing ongoing concerns over the increased incidence of seismicity.

The Oklahoma Corporation Commission’s (OCC) Oil and Gas Conservation Division announced the new rules last week as part of its ongoing efforts to stem the increase in seismic activity linked to hydraulic fracturing.

Citing data from the Oklahoma Geological Survey (OGS), the OCC explained that Oklahoma saw just two seismic events of magnitude 2.5 or greater in 2012, while in 2014, there were 359 – an increase of almost 18,000 percent. 

The new regulations will require operators in two Oklahoma counties to reduce their saltwater injections by 38 percent over the next 60 days. Last year, nearly 8.85 million barrels of wastewater were injected in the Arbuckle region, up from 7.8 million barrels in 2012. The new rules aim to reduce current disposal volumes to approximately 2.4 million barrels less than 2012 levels.

About 12 operators and 23 wells (out of approximately 3,500 statewide) will be affected by the new rules.

In March, neighboring Kansas took similar steps to reduce wastewater injection volumes after declaring earthquakes in two counties bordering Oklahoma “an immediate threat to public health, safety and welfare.” The Kansas Corporation Commission (KCC) – Kansas’ industry-regulating body – ordered operators to reduce injection in increments, starting with 16,000 barrels of saltwater per day within 10 days, and ending with 8,000 barrels per day within 100 days of the order. Violators are subject to fines of up to $10,000 per day.

More information on the new rules is available here and here.