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NMT Scientists Evaluate Risk of Rock Fractures to CO2 Storage Sites

NMT Scientists Evaluate Risk of Rock Fractures to CO2 Storage Sites 

SOCORRO, N.M. July 1, 2016 – A New Mexico Tech team, lead by Professors Peter Mozley and Mark Person and graduate students Stefan Raduha and David Butler, recently published the results of a three-year study investigating the threat of fractures in caprock to the integrity of subsurface CO2 storage sites. 

  raduha-in-the-field
 

New Mexico Tech graduate student Stefan Raduha uses a portable device to measure the permeability of rock at a study site on the western flank of the San Rafael Swell, Utah.

 

Along with colleagues from Utah State University, Sandia National Laboratories, and Los Alamos National Laboratory, the group concluded that fractures in such caprock have the potential to compromise a storage site, but only if the fractures completely penetrate the caprock. 

“Fractures that only partially traverse the caprock are actually helpful since they allow storage of CO2 in permeable caprock layers,” Person said.  “This was an interesting and unexpected result.”

One approach to mitigating the buildup of greenhouse gases in Earth’s atmosphere is carbon capture and storage (or carbon sequestration).  The idea is to capture greenhouse gases, particularly CO2, at point sources, such as power plants, before they are released to the atmosphere.  Once captured, the CO2 is compressed and then injected into porous reservoir rock deep in the subsurface.  To keep the CO2 from migrating back up to the surface, however, the reservoir rock must be overlain by an impermeable caprock. 

The team used a combination of detailed descriptions of outcrops in south central Utah, with sophisticated numerical modeling of multiphase fluid flow to arrive at their conclusions.  Mozley said that the research benefited from close cooperation between the modeling team and the geologists. 

“We even had the modelers help with the field work, which is quite unusual,” Mozley said. “The fieldwork, in particular, was lots of fun, though it did get pretty hot since we foolishly did much of our work in August.”

The study was published the international journal Geofluids (http://onlinelibrary.wiley.com/doi/10.1111/gfl.12177/full), and was funded by the U.S. Department of Energy’s National Energy Technology Laboratory (NETL).

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