Earthquake issues brought above ground
Record seismic activity has highlighted the use of hydraulic fracturing in Oklahoma, which houses a growing number of active fracturing wells.
There are 240 currently active fracturing wells. Apache Corp. built 20 wells between January and March 2011, while BP has started the operation of 13 wells between June and October in eastern Oklahoma, according to Frac Focus, the Chemical Disclosure Registry.
Chesapeake currently leads the state in fracturing activity, operating 155 active sites, with 94.1 percent of them located west of Interstate 35.
Austin Holland, Oklahoma Geological Survey expert, published a report in August examining the impact of fracturing on seismic activity in Garvin County’s Eola Field. In his research, he neither confirms nor denies the possibility of fracturing wells inducing earthquakes. His research identifies cases of “enhanced geothermal systems where there is a clear correlation between injection and earthquakes” in Colorado, New Mexico and Australia.
He also identifies cases in Nebraska, Ohio and France with “less clear examples in which earthquakes may not have been triggered by fluid injection at a well.”
“We have been trying to understand those relationships,” Holland said. “Our biggest issue is incomplete data in Oklahoma.”
Oklahoma recently has experienced a massive spike in earthquakes. In the last decade, Oklahoma has averaged about 50 earthquakes a year. In 2011, the state has been shaken by 1,047 earthquakes, according to data from Leonard Geophysical Observatory in the Oklahoma Geographical Survey.Holland said he doesn’t think these earthquakes are relevant to the study.
“The other earthquakes we are talking about are 2 kilometers deep only. But even the aftershocks in Oklahoma happened at a depth of 4-14 kilometers,” Holland said.
Holland argues that Oklahoma’s geology is very complex across the state, and because Oklahoma has rocks near the surface that contain oil, he can’t put a flat line on anything at this depth that equates an earthquake to hydraulic fracturing.
“Back in the ’40s, they were fracturing the well by using explosives,” Holland said. “In my mind, water would the more preferable constituent. Hydraulic fracturing is an incredibly important technology. It’s better than us getting addicted to fossil fuels.”