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Fluid Chemistry; Metal-Organic Interactions |
Environment Division, School of Applied Sciences, The Robert Gordon University, Aberdeen AB1 1HG, UK
Geothermal fluids form by the infiltration, heating and circulation of meteoric waters in the Earth’s crust. Rock-water reactions, boiling and condensation processes influence the chemistry of the fluids. The composition of geothermal fluids ranges from that of gold-depositing, dilute waters to saline, oil-field brines; as such they form a link between these two aqueous systems. Techniques developed to examine the processes active in geothermal systems may find valuable application in gold exploration and hydrocarbon reservoir modelling. The concept of hydrological regime is introduced and applied to recognising deposits of geothermal activity, the level of preservation and permeable, potentially gold-bearing zones in ancient epithermal systems. Mixing models, such as Cl-enthalpy plots, and geothermometry can aid identification of breakthrough of edge waters and casing damage. Differences in the equilibration time of geothermometers may enable the thermal profile or history of the reservoir to be developed. Statistical models enable major controls or sources of the solutes to be isolated, and aid in the correlation of formation waters between wells.
