Oil research on salt permeability raises questions about nuclear waste storage

Claire Allbright

Salt may be more permeable than previously thought, raising questions about whether salt isolates nuclear waste effectively, according to a new study released by researchers at UT.

Soheil Ghanbarzadeh, doctoral candidate ​in the Department of Petroleum and Geosystems Engineering, was the lead researcher and author of a thesis sponsored by Statoil, which set out to analyze if salt serves as a good seal for petroleum. The thesis findings have implications for the nuclear waste industry as well.

Currently, Germany and the United States use salt to trap nuclear waste since it was thought to be impermeable. However, if waste can flow through the brine, there is a possibility the waste can contaminate ground water, spurring a renewed interest in research about salt use. Proposals such as storing nuclear waste under Nevada’s Yucca Mountains, which do not rely on the use of salt as a barrier, have faced political and regulatory hurdles, according to a UT press release. 

Ghanbarzadeh said the oil companies hoped to discover whether salt serves as a barrier under which oil and gas would be trapped in large quantities so that it could be extracted
through drilling.

“The project started as a petroleum project, and the oil companies wanted to see whether the oil and gas can get into the salt or not,” Ghanbarzadeh said. “If it cannot get in, then it can be trapped, and you can go and drill and make money, but if the oil and gas can flow into the salt, then it can go anywhere, and you cannot collect oil and gas from the underground.”

Masa Prodanovic, assistant professor in the Cockrell School of Engineering and Ghanbarzadeh’s co-advisor, said the rock salt permeability may be caused by high pressure and temperatures but also by deformation or stretching of the rock.

“The implications of the findings is that rock salt, for instance, in potential nuclear waste storage repositories, might be more permeable to water than just based on the depth,” Prodanovic said. “So, this new piece of information needs to be considered when assessing the site.”

Marc Hesse, assistant professor in the Jackson School of Geosciences and Ghanbarzadeh’s co-advisor, said more research is needed to determine whether salt should be used in nuclear waste management.

“The main impact, I hope is that … it spurs more research,” Hesse said. “We need to understand better when this can occur, and we need to understand, if it occurs, how much fluids can come through. Now, in our research, we only saw that there were fluids; we have no idea how long it took them to get there. So what we really hope is that it’s really an opening for further research.”