OGS: Oil, Gas Wastewater Disposal Wells Likely Trigger For Most Oklahoma Earthquakes

The Oklahoma Geological Survey released a new statement Tuesday, saying that oil and gas wastewater disposal wells are likely the trigger for most of the earthquakes in central and northern Oklahoma.

According to the OGS, based on observed seismicity rates and geographical trends following major oil and gas plays with large amounts of produced water, the rates and trends in seismicity are very unlikely to represent a naturally occurring process.

According to the news release, during 2013, the OGS observed on average about 2, M3+ earthquakes each week on average, and this rate continued to increase during 2014. Currently, the OGS is reporting on average about 2 ½, M3+ earthquakes each day.

The OGS considers it very likely that the majority of recent earthquakes, particularly those in central and north-central Oklahoma, are triggered by the injection of produced water in disposal wells.

According to the news release, the primary suspected source of triggered seismicity is not from hydraulic fracturing, but from the injection/disposal of water associated with oil and gas production.

Read more of the news release here.

The release of the statement reflects a subtle change in OGS's position on the cause of Oklahoma's increased seismic activity and puts it more in line with what experts outside of the state have been postulating for some time. It also coincides with an evolving regulatory attitude taken by the Oklahoma Corporation Commission (OCC), which is responsible for permitting disposal wells.

In 2013, OCC adopted a “traffic light” approach to approving permits for individual injection wells. In March, OCC issued a new directive, requiring operators of more than 300 disposal wells in areas of high seismicity (“areas of interest') to provide proof that they are not injecting below the Arbuckle formation. There is general consensus among seismologists that injecting too close to the basement rock is likely to trigger earthquakes.