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Where Will Disposal of Wastewater from Fracking and Other Drilling Trigger Earthquakes?

Injection wells that dispose of wastewater from oil and gas drilling operations can trigger earthquakes. Stanford releases a free tool to predict the risk

2 min read

Oil drilling equipment
Photo: iStockphoto

It’s pretty clear by now that wastewater injection, a way of disposing of the brackish water used in fracking and other oil and gas drilling processes, can cause earthquakes. But, to date, the response to these injection-caused earthquakes has been reactive. After a recent earthquake in Oklahoma, the state ordered a shutdown of 37 disposal wells in the area.

Map of Oklahoma earthquake activitySince 2008, there has been a dramatic increase in the number of earthquakes, in Oklahoma. The events have been more clustered in the vicinity northeast and east of Oklahoma City and generally southwest of Tulsa.Image: USGS

This week, researchers at Stanford released a free software tool to enable energy companies and regulatory agencies to be more proactive—to calculate, before drilling a well in a particular spot, the probability that an injection there will trigger an earthquake. The Fault Slip Potential tool uses information about known faults in an area, the way stresses act in the earth, and estimates of how much wastewater injection will increase the pore pressure (that is, the pressure of groundwater trapped within tiny spaces inside the rocks below the surface).

“Our tool provides a quantitative probabilistic approach for identifying at-risk faults so they can be avoided,” said graduate student Rall Walsh in a statement to the media. “Our aim is to make using this tool the first thing that’s done before an injection well is drilled.” For the project—funded by the Stanford Center for Induced and Triggered Seismicity (SCITS) and developed in collaboration with ExxonMobil—Walsh worked with Stanford professor Mark Zoback.

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