MINVAR and UNCCON, computer programs for uncertainty analysis of solubility calculations in geological systems

Citation
C. Ekberg et al., MINVAR and UNCCON, computer programs for uncertainty analysis of solubility calculations in geological systems, COMPUT GEOS, 26(2), 2000, pp. 219-226
Citations number
21
Categorie Soggetti
Earth Sciences
Journal title
COMPUTERS & GEOSCIENCES
ISSN journal
00983004 → ACNP
Volume
26
Issue
2
Year of publication
2000
Pages
219 - 226
Database
ISI
SICI code
0098-3004(200003)26:2<219:MAUCPF>2.0.ZU;2-E
Abstract
Computer simulations of different phenonmena have become increasingly impor tant as computer time has become cheaper and computers have become faster. In some cases, it may be that simulation results are used instead of experi ments, since experiments are expensive and require a great deal of time. On e such example is the determination of solubilities of different elements u nder different conditions, e.g. different temperatures and water compositio ns. It is important when working with computer simulations, however, to rem ember that the result is a direct function of the input data, i.e. if input data are slightly uncertain, so will be the results. The main input data t o solubility calculations are thermodynamic data, such as stability constan ts and enthalpies of reactions, and water composition data. The thermodynam ic data have been discussed elsewhere, and the focus of this paper is thus on the water parameters. The uncertainties in water composition may origina te from at least two different sources. Either the water composition at a c ertain location has been measured, thus making the main measurements uncert ain, or the uncertainties in water composition arise from computed estimate s of water composition on the basis of rock-water interactions. To investig ate these different approaches, two programs, MINVAR and UNCCON, have been developed. The MINVAR program gives uncertainties in water composition caus ed by uncertainties in rock composition using the CRACKER code. These uncer tainties or measurement uncertainties may then be transferred to the UNCCON program, which estimates the effect on the calculated solubilities. Both p rograms use the Latin Hypercube sampling technique. (C) 2000 Elsevier Scien ce Ltd. All rights reserved.