The Arbuckle Group, a watery, underground rock structure, was created in southern Kansas 480 million years ago, when fish were just beginning to evolve. Since then, time has buried it as much as 8,000 feet beneath the earth’s surface.

In modern times, the 17-county area over the Arbuckle has been a profitable territory for the oil industry, but now those oil rigs are being used for a different purpose. If all goes as anticipated, instead of pumping out oil, the rigs will pump in carbon dioxide in an effort to curb climate change. Deep inside the earth, the Arbuckle’s aquifer system will become a depository for the greenhouse causing gas. With $10 million in federal grants, members of the University’s Kansas Geological Survey have drilled 5,000 feet into the Arbuckle in Sumner County, just south of Wichita, to investigate its potential for storing carbon dioxide.

South-central Kansas CO2 Project

Geologic carbon sequestration, the pumping of man-made carbon dioxide deep underground, is a nationwide Department of Energy (DOE) initiative to mitigate the effects of greenhouse gases. The DOE estimates that geologic formations in the U.S. such as saline aquifers and oil and gas reservoirs have the potential to absorb the nation’s total output of carbon dioxide from fossil fuel emissions for the next 600 years. By trapping carbon dioxide underground, policy makers hope to help the U.S. meet its goal of halting the increase in greenhouse gas. They also hope to make a new industry as private businesses find economic incentives to dispose of carbon dioxide.

However, some studies question current estimates of the volume of carbon dioxide those geologic spaces can hold, while others raise questions about groundwater contamination.

“The 800-pound gorilla in the room is putting it in the ground safely,” said W. Lynn Watney, senior KGS scientific fellow. “We’re trying to prove the concept so that it will be palatable to regulators.”

Both Watney and Saibal Bhattacharya, the lead KGS engineer, are the principal investigators of the project. Their team is using oil rigs and advanced seismic imaging technology to test the Arbuckle aquifer’s ability to store carbon dioxide within the saltwater and pores in the rock. The KGS initially received a $5 million grant from the DOE in 2009 and received another $5 million last month.

Watney said the goal of the project, which is to be completed in December of 2012, is to measure the volume and test the safety of the Arbuckle. The current project plan does not involve any injection.

CO2 as Oil/Gas Industry Tool

The petroleum industry has been injecting carbon dioxide into the earth for more than 30 years, but not for the purpose of trapping it. Enhanced oil recovery is the industry term for pumping carbon dioxide into oil or gas reservoirs in order to increase productivity. As practiced today, it has no significant impact on greenhouse gas emissions.

The KGS has subcontracted with petroleum firms such as Berexco LLC, Beredco Drilling and Bittersweet Energy Inc. in order to accomplish the drilling, gain access to practical expertise and draw private industry into the business of carbon dioxide.

“If the industry looks at it as an asset, they might help build the pipeline and make it feasible for a power plant,” Watney said.

Statoil, a major Norwegian oil and gas company, has been conducting large-scale, commercial carbon sequestration in the North Sea since 1996. Carbon sequestration projects are now underway at dozens of locations in the U.S., funded in part by the Department of Energy.

Dana Wreath, vice president of Brexco, said the project was an unusual one for his company.

“You could be seeing a new industry created,” Wreath said. “The preliminary information is that it looks good.”

Other Studies Raise Questions

Not all researchers are convinced carbon sequestration is the answer to reducing greenhouse gases.

The research of Mark Little and Robert Jackson at Duke University’s Center on Global Change showed that carbon dioxide could contaminate groundwater with metals and potentially dangerous uranium and barium if it leaked from underground storage.

Another study questioned the feasibility of storing large amounts of carbon dioxide underground. A paper published in the Journal of Petroleum Science and Engineering by Christine Ehlig-Economides and Michael Economides asserts that many researchers have vastly overestimated the quantities of carbon dioxide that most geologic formations can hold. The researchers used mathematical models to make their own estimates of how much space is available in underground reservoirs.

Michael Economides earned his bachelor’s and master’s degrees in chemical engineering at the University of Kansas and is now a University of Houston professor of chemical engineering. Economides said using sequestration to mitigate against climate change was not feasible, and that many researchers and government officials were promoting unrealistic projections.

“Not only is it not going to happen, but it is ridiculous that we’re even talking about it,” Economides said.

Watney said the Economides’ estimates assumed a closed space, whereas formations like the Arbuckle may extend for over 200 miles in any direction.

“For our purposes, this is an infinite aquifer,” Watney said.

— Edited by Brittany Nelson