A new study has found that earthquakes in the state may be triggered by fracking wastewater.
Researchers from the University of Colorado and Cornell University say they have some new scientific evidence to support their observations that frack quakes are to blame for the giant group of earthquakes that have hit central Oklahoma, which they believe were likely caused by disposal well activity where wastewater from hydraulic fracturing and other drilling operations is forced into the ground.
Oklahoma is currently the second most seismically active state in the continental U.S.
So far, in 2014, based on earthquake figures from the U.S. Geological Survey database, Oklahoma has experienced over 230 quakes. According to a study recently published by the journal Science, it is theorized that the wells have caused over 100 small to mid-sized earthquakes between 2008 and 2013. Four high-rate disposal wells, in particular, which are located in southeast Oklahoma City, are what likely provoked the “Jones swarm”, the name given to the group of quakes that made up 20% percent of the seismicity in the eastern and central U.S. during the last five years.
The water that is injected into the four wells named Deep Throat, Sweetheart, Flower Power and Chambers, has more than doubled since a decade ago when the drilling boom first began. The more water that is injected, the more wastewater requires disposal. Over 4 million barrels of fluid are discarded monthly by the four wells.
Hydraulic fracturing is a mining process that requires a mixture of water, chemicals and sand to be injected deep down beneath the earth’s surface at a high pressure for the purpose of breaking up rocks underground that contain natural gas or oil so these substances can be extracted.
When the high-pressure fluid is forced into the rock formations, it increases the pressure within the pores of these formations. According to Shemin Ge, the study’s senior author and a hydrogeology professor at the University of Colorado, Boulder, earthquakes can be triggered in faults that preexist or in other areas where geological weakness is present from the increased pressure.
Frack quakes occurred at a greater distance away from the wells than was expected.
The researchers also discovered that many of the quakes within the state occurred farther away from the wells than anticipated. Previously, scientists thought that wells could only trigger quakes that were within a 5 km range from the well. However, this recent study utilized computer simulations and learned that huge amounts of water travel as far as 32 kilometers away from the well. This could mean that the pressure is triggering preexisting small faults or undiscovered ones. In other words, frack quakes could be occurring far away from the wells.