News Release, Kansas Geological Survey, Dec. 30, 2010

Kansas Geological Survey receives grant to test tool for predicting CO₂ storage potential

LAWRENCE--The Kansas Geological Survey, based at the University of Kansas, will use a $1.5 million award from the U.S. Department of Energy to test a technique that could cast light on the potential for sequestering carbon dioxide in the deep subsurface of south-central and southwestern Kansas.

The researchers will use a new tool, called volumetric curvature, to analyze data from seismic reflection, a technique commonly used in oil exploration to create images of underground rocks without the necessity of drilling.

CO₂ sequestration--the containment of CO₂ from industrial processes and other sources--is not currently practiced in Kansas but is being explored worldwide in an effort to reduce the greenhouse gases released into the atmosphere.

One target for sequestration in south-central and southwestern Kansas is a deep saline aquifer called the Arbuckle. The Arbuckle is a porous rock formation more than 3,500 feet deep, up to 1,000 feet thick, and is isolated by numerous impermeable layers, or cap rocks, from the much shallower High Plains aquifer that provides most of the region's fresh water. Because water in the Arbuckle is unusable, it is a candidate for sequestration.

The Arbuckle must be better defined, however, before CO₂ sequestration is considered. Paleokarst--a landscape of ancient caverns and sinkholes formed in limestone and other soluble rocks now buried beneath thousands of feet sediment--sits atop the Arbuckle and could pose problems if its extent is not identified.

"We'll use the volumetric curvature tool to describe the extent of paleokarst features and associated faults," said Jason Rush, joint principal investigator on the project with Survey researcher Saibal Bhattacharya.

The tool will be operated from the surface to analyze seismic data collected at the study area. Survey researchers will then work with industry partners Murfin Drilling Company and Vess Oil Corporation of Wichita to drill a horizontal borehole in Ellis County into paleokarst features identified by the seismic data analysis.

The borehole will start out vertical, then gradually turn until it reaches a horizontal trajectory in the uppermost Arbuckle. Measurements and images collected from the borehole will be compared to maps generated by the volumetric curvature to confirm the effectiveness of the tool.

"Along the horizontal length of the well, about 1500 feet, cores and fluid samples will be recovered and pressure tests recorded to model the way a plume of CO₂ would interact with paleokarst," Bhattacharya said. "This data also will be used to determine the containment or flow of CO₂ injected into the sub-surface."

If successful, the seismic data analysis tool would provide a cost-effective way to assess geologic CO₂ storage capacity and lead to a better understanding of the underground movement of CO₂ in the Arbuckle and other deep saline aquifers.

"This tool will also benefit the oil and gas industry by helping them locate wells in large, undrained reservoir compartments, which increases the odds of getting a productive well," said Bhattacharya.

"If the Arbuckle saline aquifer proves to be a good candidate for sequestration, the benefits would include the potential for commercial-scale sequestration operations in the state that would reduce CO₂ emissions to the atmosphere," Rush said. "CO₂ also can be injected into depleted oil reservoirs to sweep bypassed oil not recoverable by traditional methods, thereby increasing state revenue and reducing oil imports."

The results of this research will augment other ongoing Survey studies assessing the potential for CO₂ sequestration in central and western Kansas.