Earth Scientists Talk TOUGH

March 31, 1995

By Mike Wooldridge,

About 100 earth scientists from around the world came to LBL last week to talk TOUGH. The Earth Sciences Division held a three-day workshop devoted to a popular fluid simulation program developed at the Lab--Transport of Unsaturated Groundwater and Heat, or TOUGH.

ESD's Karsten Pruess, the conference organizer, created the first version of TOUGH in the early 1980s for tracking the flow of water and vapor in geothermal reservoirs. Since then, the program has been modified for many other earth science specialties. Versions of TOUGH now model the movement of water, oil, solvents, toxic waste, heat--practically anything that flows underground and is of interest to scientists and engineers.

The conference was a chance for earth science researchers from a wide variety of disciplines to share their experiences. "It's all about dialogue," Pruess says. "The underlying physics of fluid flow in porous media is basically the same across different applications. A fluid doesn't care whether it's part of an environmental investigation or part of a geothermal study."

One advantage of programs such as TOUGH is that researchers can conveniently and inexpensively study the "what ifs" of a project. Scientists working on nuclear waste clean-up, for instance, can model a toxic site and try out different strategies for cleaning it up, all on a computer.

TOUGH simulation can also be key in site assessment. The software has been particularly useful at Yucca Mountain, Nevada, where DOE plans to construct a major facility for nuclear waste storage. "Even with all the bore holes drilled and samples taken, much of Yucca Mountain still isn't directly accessible to scientists, and never will be," says Pruess. "Numerical simulation plays a very large role in understanding the site."

In addition to the software's role in nuclear waste isolation and environmental clean-up, the conference also looked at TOUGH simulation in oil exploration, mining engineering, and geothermal engineering.