For earthquake study, Kansas extends limits on wastewater from drilling

State officials on Thursday extended oil-waste dumping rules that were put in place to try to reduce earthquakes in southern Kansas oil fields.

The main idea: Scientists have identified underground disposal of drilling wastewater as a probable cause of the earthquakes that have rattled homes and nerves in Harper and Sumner counties south of Wichita since 2013. In March, the Kansas Corporation Commission ordered a six-month slowdown in wastewater disposal, and on Thursday extended that to March 2016 to allow for more monitoring.

Is fracking causing quakes? Technically, no, experts say. Fracking, from the industry term “hydraulic fracturing,” is a means of increasing oil production by using high-pressure fluids to break underground rock and free trapped pools of oil. That by itself doesn’t cause anything more than very weak ground movement, according to Kansas Geological Survey scientists.

But fracking did expand oil production and with it, the amount of wastewater. Scientists believe the quakes are caused by injecting that water into rock formations deep underground to get rid of it.

How does water cause earthquakes? Poured or pressure-injected into deep underground formations, it can upset the balance between different types and layers of rock that are under enormous pressure. That can cause the rocks to shift, causing the tremors we feel at ground level.

Where’s all that wastewater coming from? It’s been trapped underground for ages. For every barrel of oil from a southern Kansas oil field, producers get about 16 barrels of water. It’s too salty and oily to dispose of above ground.

Is the plan working? That’s unclear. There has been a general decline in the number and magnitude of quakes since the reduction in wastewater injection took effect. But October brought a spike in quakes between magnitude 3 and 4.

What’s next: The additional six months will give scientists more data, collected over a longer period of time, to better study the relationship between wastewater injection and earthquakes, and evaluate whether the disposal limitations are having the desired effect.

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