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Van Tuyl Lecture: Dmitri Kulik, Paul Scherrer Institute, Switzerland
April 25 @ 4:00 pm - 5:00 pm
Dmitri Kulik, Paul Scherrer Institute, Switzerland
241 Berthoud, 4-5PM
Topic: GEMS for Geochemical Modeling of Fluid-rock Interaction and Radioactive Waste Disposal
Abstract: Geochemical systems usually consist of aqueous, gaseous and many possible mineral phases, including solid solutions and/or sorption. Their evolution often involves reactive transport phenomena, represented at any given time point by local- and partial equilibrium states, understanding and prediction of which requires computer-aided thermodynamic modeling. GEMS is a geochemical modeling software based on Gibbs Energy Minimization (GEM) and developed at PSI. The GEM method is best applicable to hydro-thermal fluid-rock interaction and ore formation, and to compacted porous systems such as sediments, clays and cements. Complementary chemical speciation codes (e.g. PHREEQC, GWB), based on the Law-of-Mass Action (LMA) method, are broadly applied to aquatic systems in petroleum- and environmental geochemistry. GEM and LMA programs require different input thermodynamic databases and have their own pros and cons, both as standalone codes or coupled with advection-diffusion or box-flux algorithms for reactive transport simulations. Recent studies lead to an extended xLMA method of the same power as GEM. An overview of typical applications of GEMS at PSI, Empa, ETHZ and CSM will touch radioactive waste disposal, cement chemistry, geothermal and fluid-rock interaction systems.