Scientists from the Energy Geosciences Division at Lawrence Berkeley National Laboratory (LBNL) have released the latest version of TOUGH (Transport Of Unsaturated Groundwater and Heat), a suite of software codes used worldwide to simulate nonisothermal multiphase flow and transport in fractured and porous media. TOUGH3 builds on the impressive legacy of its TOUGH predecessors, which have broad applications for coupled thermal, hydrological, geochemical, and mechanical processes in permeable media.
The TOUGH codes were originally developed at LBNL beginning in the early 1980s primarily for geothermal reservoir engineering. The software suite has evolved over the years to address a wide variety of needs by a large user base at universities, government organizations, and private industry. Today, the applications of the TOUGH codes have expanded to include geologic carbon sequestration, hydrocarbon recovery including gas hydrate deposits, vadose zone hydrology, and environmental remediation in addition to geothermal and enhanced geothermal systems.
Recently the TOUGH codes have found use in two of the highest-profile environmental disasters of the last decade. Specifically, TOUGH2 was used in 2010 to simulate the flow of oil and gas leaking into the Gulf of Mexico from the blown-out Macondo Well drilled from the Deepwater Horizon platform, and five years later to model the flow of methane from the blown-out SS-25 well at the Aliso Canyon underground storage facility in southern California. In both cases, simulations carried out using the TOUGH code T2Well were instrumental in quantifying and understanding the coupled flow processes controlling leakage.
The TOUGH suite of simulators is continually updated for ease of use and added capabilities, and currently includes TOUGH3, TOUGH+, TOUGHREACT, iTOUGH2, and TOUGH-FLAC. Consolidating more than a decade of independent developments by multiple researchers, TOUGH3 adds the capability to facilitate parallel execution enabling the code to exploit multi-processor computers with a single flagship simulator.
The new capabilities embodied in TOUGH3 were developed by Energy Geoscience Division researchers George Pau, Yoojin Jung, and Stefan Finsterle over the last five years. Curt Oldenburg, a senior scientist in the Energy Geosciences Division at Berkeley Lab, led a small group of scientists in the final testing and documenting of the code for licensing and release.
Oldenburg is very excited about what TOUGH3 offers TOUGH users who need a flow simulator developed for a wide range of application areas. “What’s really special about TOUGH3 is its ability to run large problems with great accuracy by virtue of the new parallel solvers available in the code,” says Oldenburg. “This single code can take advantage of computers with two processors to more than a thousand processors.”
The software also incorporates numerous bug fixes, several new EOS modules, and more flexible input options, such as time-dependent GENER block, relative to the old code TOUGH2. Experienced users of simulators from the TOUGH family, however, will find a lot that is familiar. Subroutines performing the flow, transport, and phase equilibria functions, for example, remain relatively unchanged from predecessor TOUGH versions developed by Karsten Pruess and others over the last several decades.
A test of TOUGH3 (by Antonio Rinaldi, ETH Zurich) showed its potential to simulate very large problems using parallel linear-equation solvers. When cold water was injected into a homogeneous geothermal reservoir discretized into 853,128 volume elements (grid blocks), run time significantly improved as the number of processors increased.
Another enhancement to the newest of TOUGH simulators is its ability to automatically allocate problem size-dependent arrays during initialization. Oldenburg explains, “In the old days, you would have to dimension the arrays or variables according to the problem size before you ran the code. In TOUGH3, it’s done automatically.”
TOUGH3 is now available through the Lawrence Berkeley National Laboratory licensing website. A user guide is available here. Development of TOUGH3 was partially supported by TOUGH royalty funds provided by revenue from the licensing of the TOUGH codes.
As with previous versions of the TOUGH codes, users of TOUGH3 will have access to a large, collaborative community of users through the online TOUGH Forum.
Early response to the new codes has been positive. When testing TOUGH3 for the application shown in Figure 1, for example, long-time TOUGH2 user Antonio Rinaldi (ETH, Zurich) was moved to email his feedback. “I admit I already love TOUGH3, it really is an improved TOUGH2!” Rinaldi wrote. “I am now looking forward to trying all the different new features and additions.”