Meeting speaker shakes notions about quakes

More than 125 people attended the 69th annual Marion County Conservation District?s dinner and meeting.

In addition to recognizing conservation award winners, Rex Buchanen, interim director of the Kansas Geological Survey?University of Kansas, was the guest speaker.

Buchanen?s presentation, ?Recent Seismic Activity in the Midcontinent: Events and Responses,? focused on the possibility of earthquakes associated with saltwater disposal from hydraulic fracturing.

Earthquake activity in the Earth?s crust is known as seismicity, but when linked to human activities, it is referred to as induced seismicity, he said.

Along with oil and gas production, other induced seismicity, Buchanen said, include mining, geothermal energy production, construction, underground nuclear testing and impoundment of large reservoirs.

Earthquakes associated with oil and gas production are rare. But seismic activity associated with oil and gas production operations is thought to be triggered when wastewater is injected into a disposal well.

?In this disposal process,? he said, ?waste products, such as saltwater produced with oil and gas and recovered hydraulic fracturing fluids, are injected into deep and confined porous rock.?

Buchanen said when he grew up in Rice County in the 1950s and 1960s, he can remember people referring to evaporation pits.

?People put saltwater into big pits in the ground and said it evaporated,? he said. ?But it didn?t evaporate. It went into the shallow subsurface and contaminated the groundwater.?

According to Buchanen, there are places near Wichita and the Burrton area still dealing with saltwater contamination from those old evaporation pits?now 70 years ago.

 

Fracking is a technique in which a hole is drilled in the subsurface either horizontally or vertically, he said. Water and pressure with chemicals injected in the rocks create very small earthquakes of zero magnitude or even smaller.

?What we are talking about is not the earthquakes caused by that low level energy that goes in the ground with hydraulic fracturing,? Buchanen said.

?What we are talking about is the possibility of earthquakes associated with saltwater disposal.?

For every barrel of oil produced, he said, several barrels of saltwater are also produced.

Rocky Mountain Arsenal

Although Buchanen talked primarily about Kan?sas and Oklahoma earthquakes, he did discuss how the Rocky Mountain arsenal (RMA) in the 1960s and fluids in the ground triggered earthquakes.

?Humans can cause earthquakes,? he said.

Buchanen said the RMA contained a deep injection well drilled to a depth of 12,045 feet. The well was cased and sealed to a depth of 11,975 feet, with the remaining 70 feet left as an open hole for the injection of basin liquids.

The well was injected with about 570,000 gallons of water from the city prior to injecting any waste.

The U.S. Army discontinued use of the well in February 1966 because the fluid injection triggered a series of earthquakes in the area.

Earthquakes in Ka

The 69th annual meeting drew more than 125 people to the meal and program at Eastmoor Methodist Church. Patty Decker / Free Press
The 69th annual meeting drew more than 125 people to the meal and program at Eastmoor Methodist Church. Patty Decker / Free Press
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The largest documented earthquake in Kansas was near Wamego in 1867, he said. It rocked buildings, cracked walls, stopped clocks, broke windows and reportedly caused ground to sink and endangered the bank of a canal near Carthage, Ohio.

That earthquake, Buchanen said, was probably associated with the Nemaha Ridge, a 300-million-year-old buried mountain range extending from Omaha to Oklahoma City.

?The Humboldt fault zone, on the eastern boundary of the Nemaha Ridge, is still slightly active,? he said.

The damage caused by the Wamego earthquake was estimated to have a magnitude of 5.2.

?At least 25 earthquakes in Kansas were documented in newspaper accounts between 1867 and 1976,? he said.

Before 2013, the only reported instance of possible induced seismicity in Kan?sas occurred in 1989 when small earthquakes were recorded near Palco in Rooks County, about 30 miles northwest of Hays.

The largest, a magnitude of 4.0, caused minor damage.

Several injection wells used for the disposal of wastewater, extracted during conventional vertical oil well operations, were located in the area, he said.

One well, in particular, may have been close to a deeply buried fault zone.

?Based on that well?s injection history, local geology, and low level of prior earthquake activity in the area, scientists speculated that the seismicity could have been induced,? he said.

In 2013 and early 2014, several earthquakes were recorded in south-central Kansas in the vicinity of wastewater injection wells.

In Harper County, a magnitude 2.9 earthquake was recorded in September 2013, and in Sumner County earthquakes measuring magnitude 3.8 and 3.9 were recorded in December 2013 and February 2014, respectively.

Whether oil activities played a role has not been determined, Buchanen added, but more information is needed.

Large earthquakes

One of the largest earthquakes in Kansas was Nov. 12 with a magnitude of 4.8 near the town of Milan in Sumner County.

Buchanen said that earthquake caused damage to the old post office and other buildings in Milan.

Another small town, Prague, Okla., had a magnitude 5.6 earthquake in 2011, he said. It was considered the most powerful earthquake reported in Oklahoma.

While some scientists believed the earthquake was triggered by the cumulative effects of injecting saltwater under high pressure into the subsurface, he said, state seismologists said the quake was natural.

State involvement

In January 2014, a task force on induced seismicity, was formed with members of the Kansas Geological Survey, Kansas Corporation Commission, and Kansas Department of Health and Environment.

The task force was charged with developing a an action plan for induced seismicity.

Seismic activity continues to be an issue in south-central Kansas, he said.

The U.S. Geological Survey in 2014 has recorded 54 earthquakes, ranging from magnitude 1.3 to 3.4, and nearly all were in Sumner, Harper and Barber counties, Buchanen said.

?That is a significant increase over seismic activity in 2013 and the years prior to that,? he said.

The task force recommended to Gov. Sam Brownback that increased monitoring is recommended to better understand this phenomenon.

Previous studies showed that earthquakes can be triggered by fluid injection, and the U.S. Geological Survey found that ?at some locations the increase in seismicity coincides with the injection of wastewater in deep disposal wells,? he said.

According to information provided by Buchanen, fluid injection near a fault, under a certain set of conditions, can cause a fault to move, resulting in an earthquake.

In the report to the governor, Buchanen said significant amounts of salt water are produced along with oil and natural gas in the United States, including Kansas.

This salt water is generally injected back into the deep subsurface for disposal or as part of enhanced oil recovery projects.

These injection wells are designed and permitted to ensure potential drinking water supplies are not compromised.

?There are approximately 16,000 (of these wells) in Kansas used to inject waste fluids from oil and gas operations,? he said. ?The majority of wells in Kansas are used for EOR projects and about 5,000 serve as disposal wells.?

The injection of salt water should not be confused with hydraulic fracturing, he added.

While hydraulic fracturing does create micro seismic events, which are too small to feel, the events are nearly always localized and not considered a significant hazard.

The USGS has stated that felt earthquake activity, which is generally greater than a magnitude 2.5, in the midcontinent resulting from hydraulic fracturing has been reported from only a handful of locations.

There is no evidence to suggest hydraulic fracturing itself is the cause of the increased rate of earthquakes,? according to the USGS.

In order to determine if there is a connection between recent earthquakes and fluid injection wells in Kansas, Buchanen said, more spaced monitoring stations need to be closer to injection sites.

?Increased access to data pertaining to the injection process, especially the volume of fluid injected over a specified period and the amount of pressure used to inject it, is also vital,? he said. ?It is also a state issue.?

For more information about earthquakes, Buchanen suggested people google ?earthquakes usgs,? which will show recent earthquakes and other information.