Induced Seismicity

The number of recorded earthquakes in Kansas had risen substantially since 2013 based on data from the USGS National Earthquake Information Center (NEIC). USGS data shows that from 1981 through 2010, Kansas experienced 30 recorded earthquakes. In 2013, there were four recorded earthquakes in Kansas. That number increased to 127 in 2014. From January 1, 2015, to March 16, 2015, Kansas experienced 51 recorded earthquakes. The majority of the earthquakes occurred in Harper and Sumner Counties.

In response to the increased seismic activity, Kansas Governor Sam Brownback established a task force, led by the Kansas Geological Survey (KGS), and comprised of the Kansas Corporation Commission (KCC), and Kansas Department of Health and Environment (KDHE), with direction to study and develop a State Action Plan for potential induced seismicity. The Induced Seismicity Task Force met six times. Experts were consulted from the U.S. Geological Survey, the Oklahoma Geological Survey, and private industry. The Task Force developed a draft Seismic Action Plan and made revisions based upon public and stakeholder comments then resubmitted the plan for public comment before final adoption.

Seismic Action Plan

The Seismic Action Plan consists of two major components - a plan for enhanced seismic monitoring and a response plan. Enhanced seismic monitoring includes installation of a strategically located permanent monitoring network that will allow all earthquakes in Kansas greater than magnitude (M) 1.5 to be detected and located. It also includes the acquisition of a portable seismic monitoring array that will allow researchers to increase monitoring in specific areas to further delineate seismic data. The response portion of the plan introduced a Seismic Action Score system for evaluating earthquakes. The plan defines "felt" earthquakes at M 2.5 or above.

Commission Order

Citing K.S.A. 2014 Supp. 77-536(a), and to protect the public from immediate danger to health, safety, and welfare, the Kansas Corporation Commission issued an order under Docket No. 15-CONS-770-CMSC (Order) limiting the amount of saltwater disposal rates for more than 70 wells in Harper and Sumner County, KS to monitor the effects on seismic activity. The order limited all Arbuckle disposal wells to no more than 25,000 barrels of fluid per well, per day in Harper and Sumner Counties. It also defined large volume Arbuckle disposal wells as those injecting more than 5,000 barrels per day in these counties and imposed daily monitoring and monthly reporting requirements for all large volume Arbuckle disposal wells. The order identified five areas of seismic concern based on the clustering of earthquakes which triggered a response based on the Seismic Action Score from the Seismic Action Plan. At certain intervals during the 180 days, the maximum allowed volume of saltwater disposal decreased for the 23 wells within the five areas of concern. The order also required confirmation of drill depth for Arbuckle injection wells in the five areas of concern to ensure the well bore did not penetrate deeper than the base of the Arbuckle formation. Commission staff reviewed log data for the wells in these areas and required the operators to verify the true vertical depth of the wells. The operators of wells penetrating below the base of the Arbuckle formation were required to perform remedial cementing to confine disposal into the Arbuckle formation.

Portable Seismic Array

The State Action Plan recommended the acquisition and use of a portable seismic array, which allowed the Kansas Geological Survey to deploy monitoring stations in areas with significant seismic activity to better understand the cause of localized earthquakes. The seismic monitors have been strategically placed in South Central Kansas and have collected important data resulting in a better understanding of the seismic activity over time. The Portable Seismic Array also provides greater accuracy and more granular data allowing KGS to accurately track smaller earthquakes that are not felt.

Findings

The majority of seismic activity in Harper and Sumner Counties corresponds with the identified areas of seismic concern. 120 days after the order became effective there were 87 fewer earthquakes than the same timeframe prior to issuance of the order according to data from the USGS NEIC website. In the 180 days prior to the Commission order, there were 47 earthquakes M 3.0 or larger. In the 180 days after the Commission order, there were 20 earthquakes M 3.0 or larger.

Conclusion

Since the implementation of the order, felt seismic activity is trending downward in Harper and Sumner County, as well as the five areas of seismic concern. While the downward trend of occurrences and magnitude can be viewed as positive news, it must also be viewed cautiously because the results are not conclusive. There are external factors not included in this data, such as crude oil production levels, reduced drilling activities, and other factors related to the reduced price of crude oil. Crude oil production has gone down and drilling activity has declined from 3,797 wells spudded January 1, 2014, through September 2, 2014, to 1,168 wells spudded during the same time frame in 2015.

Timeline of Events

February 17, 2014
Governor Brownback appoints the Induced Seismicity Task Force to study and report on the increased seismic activity. The task force is comprised of representatives from the Kansas Geological Survey, Kansas Corporation Commission and Kansas Department of Health and Environment.

September 26, 2014
Task Force submits State Action Plan to Governor Brownback.

January 2015
Portable seismic array deployed.

March 19, 2015
Kansas Corporation Commission issues an order limiting wastewater disposal in Harper and Sumner counties.

March 29, 2015
Day 10, all wastewater disposal wells in Harper and Sumner counties limited to 25,000 barrels per day. The maximum allowed daily disposal volume in areas of seismic concern reduced to 16,000 barrels per day per well.

May 13, 2015
Day 55, maximum allowed daily disposal volume in areas of seismic concern reduced to 12,000 barrels per day per well.

June 27, 2015
Day 100, maximum allowed daily disposal volume in areas of seismic concern reduced to 8,000 barrels per day per well.

June 27, 2015 Sept. 15, 2015
Wells remain at 8,000 barrels per day per well maximum disposal volume in areas of seismic concern for evaluation and monitoring.

September 14, 2015
KCC staff recommends extending observation and monitoring period.

October 16, 2015
The Commission issued an order extending the volume reductions and monitoring period for 180 days.