Preliminary data shows the number of ‘felt’ earthquakes in Harper and Sumner counties has decreased since Kansas regulators set limits on drilling wastewater disposal. Regulators say they want to continue new limits on such disposal operations.

Early study findings suggest that as the amount of allowable wastewater disposal gradually decreased, there was a corresponding reduction in the strength of earthquakes.

Seismic monitoring also indicates the number of ‘unfelt’ earthquakes below magnitude of 2.5 have increased at the same time.
Staff from the Kansas Corporation Commission told the Harper County Commission Tuesday that it is recommending that KCC continue the existing limits.

The agency said in a news release that its staff also is recommending continued study of seismic activity and its relationship to large-volume disposal, but say the data is encouraging.

Oil wells typically produce a lot of saltwater, or brine, which is typically injected back underground. The average in Kansas ranges from 15 to 30 barrels of saltwater produced for every barrel of oil.

Data submitted by the KCC show more than 100,000 barrels (4.2 million gallons) were disposed in this manner in Harper County last year, nearly tripling the amount reported the year before.

KCC is expected to formally review the recommendations in mid-September.

(The Associated Press contributed to this report)