Lawrence Berkeley National Laboratory

This report describes modifications made to the EOSN module (Shan and Pruess, 2003) of the nonisothermal multiphase flow simulator TOUGH2 (Pruess, et al., 1999). The EOSN fluid property module simulates transport of water, brine, air, and noble gases or CO2 in the subsurface. In the standard version of the EOSN module, diffusion coefficients can be specified by the user, but there is no allowance for liquid-phase diffusion coefficients to change with temperature. Furthermore, users must specify radiogenic sources of heat and helium for each element in data block GENER, which can be a time-consuming task for models with large numbers of elements. Our modifications seek to increase the functionality and efficiency of using TOUGH2-EOSN by allowing for mass- and temperature-dependent liquid-phase diffusion coefficients for helium and neon and specification of radiogenic heat and helium production as a property of a material. The modified version is based on TOUGH2-EOSN and thus requires familiarity with the capabilities and input formats of the TOUGH2 code (Pruess, et al., 1999) and the EOSN module (Shan and Pruess, 2003). This report only details our modifications and how to properly utilize them.