Oklahoma has experienced a major increase in earthquakes in recent years, including one biggie that damaged 200 buildings — and measured 5.6 magnitude — in November 2011. Swarms of quakes have continued in 2013.
Are the Earthquakes Related to Oil and Gas Drilling?
Several scientists have suggested that disposal wells, used to dispose of waste from some oil and gas drilling operations — including hydraulic fracturing, or “fracking” — could be the cause of the recent spike.
More than 10,000 underground injection wells were active in Oklahoma as of January 2013, data from the state Corporation Commission show. About 6,000 of these wells are a type of injection well used for enhanced oil recovery, says the commission’s injection well manager Charles Lord.
The remaining 4,400 are disposal wells used to store drilling waste, Lord says. Most of these disposal wells store waste between 10,000 and 20,000 feet underground.
Visualized: Oklahoma Injection Wells
Source: Oklahoma Corporation Commission | Download Data
Who Are These Scientists and What Have They Found?
A report issued last year by the U.S. Geological Survey found that most of these new earthquakes have taken place near active injection wells. Geophysicist William Ellsworth, the lead author of the report, wrote that it is completely plausible that the high water pressure often used in wastewater injections could nudge previously dormant faults out of their “locked” positions. The quakes, he wrote, are “almost certainly manmade.”
Scientists at Columbia University came to a similar conclusion after studying a rare 4.0 earthquake that took place in Ohio in 2011. The findings prompted state officials to enact broad new regulations and halt the use of any injection wells near faults. Regulators also shut down injection wells in Arkansas that same year following a cluster of quakes there, including one that measured 4.7 on the Richter scale.
University of Oklahoma seismologist Katie Keranen, who has studied a 5.6 earthquake that hit Oklahoma in November 2011, found the link between the “zone of injection” and the seismic activity “compelling.” There are three deep injection wells within two-and-a-half miles of that quake’s epicenter, according to Energy Wire.
None of these reports have claimed to have absolute proof that the two are linked. In other words, there is no scientific certainty surrounding the phenomenon.
The Oklahoma Corporation Commission, which regulates oil and gas activity in the state, points to that fact to explain its current “wait-and-see” approach. To date, Oklahoma does not have any regulations regarding injection wells and fault lines. Spokesman Matt Skinner says the commission is “keeping an open mind” about the recent and ongoing research.
If There is a Connection, What Can Be Done?
The National Research Council‘s list of best practices for drillers and disposal well operators includes investigating any potential disposal site’s history of earthquakes and its proximity to fault lines. Some states, like Ohio, are doing just that, and are forbidding any deep injection wells near fault lines.
Cliff Frolich, the Associate Director of the University of Texas Institute for Geophysics, says such moves are smart policy. He also suggests that companies look for new ways of disposing of wastewater altogether. “If disposal is causing earthquakes you can find a different way of dispose of it,” he said. ”You can dispose of the stuff in a different well, or you can even take it to a fluid treatment plant.”
Of course, he added, such processes are costly and therefore companies’ willingness to do that will depend largely on what states require of them.