While the state’s oil and natural gas industry activity has picked up in recent years, Oklahoma also has experienced an unexplained swarm of earthquakes.
More than 220 earthquakes magnitude 2.5 or higher were reported in Oklahoma in 2013 — more than any other year in state history.
The Oklahoma Geological Survey, the U.S. Geological Survey and others have been studying whether the state’s swarm of quakes over the past few years is connected to water injection wells. The average oil well in Oklahoma produces about 10 times as much saltwater as oil. Most of that water is returned deep underground through saltwater disposal wells.
One report co-authored by a former University of Oklahoma professor and a U.S. Geological Survey researcher connected the state record 5.7 magnitude quake in 2011 to an injection well near Luther, but the Oklahoma Geological survey has said the incident appears “consistent with a natural earthquake.”
Injection and disposal wells have been used for much of the state’s history. While oil and natural gas activity has picked up in Oklahoma in recent years, oil and water production still pale compared to levels seen in the 1980s and 1920s.
Oklahoma is dotted with more than 4,500 private and commercial water disposal wells. More than 6,600 enhanced recovery wells throughout the state are used to pump water into a producing rock layer in an effort to push oil through a rock formation.
“Crude oil and natural gas are produced in 70 of Oklahoma's 77 counties, so any seismic activity in the state is likely to occur near oil and gas activity,” Oklahoma Independent Petroleum Association spokesman Cody Bannister said.
Others in the industry have taken a more pragmatic approach.
Walter Dale, strategic business manager of water solutions at Halliburton, is working to help the industry recycle produced water, allowing companies to reduce or eliminate the amount of freshwater they use for hydraulic fracturing, or fracking.
“I have no idea if disposal wells cause earthquakes, but if you have enough demand, you don’t need to dispose it. You can recycle it,” Dale said.