Geochemical Evaluation of Fluids and Scales from Romanian Geothermal Production Wells of Bihor

Chemical data interpretation is of major importance for maintaining a good production well. The credibility of the results of the laboratory analysis depends on the care taken in the collecting of samples and the analytical procedures adopted. The results of analysis of main elements in the water samples, the concentration of trace elements and nutritient components, as well as trace of heavy metals concentration in the water from the studied wells will be summarized for each well. For an initial classification, we will use diagrams calculated by the AqQa program. Then by using Giggenbach and Arnorsson triangular diagrams, we will have information regarding the water-rock equilibrium. The chemical geothermometers are the most important geochemical tool for exploration and development of geothermal resources. Geothermometers will be used to estimate subsurface temperatures, below the zone of cooling, expected to be encountered by drilling, using the chemical composition of wellhead waters. For geothermal wells where scaling problems have been recorded, metallic coupons will be installed into a laboratory set up, geothermal water from the well will be kept at a certain temperature for different periods and samples will be taken of the solid deposition. In order to do a chemical control of deposition and to find out the most efficient chemical additive, an experimental laboratory setup is installed, where geothermal water is running, first at wellhead temperature and later at a lower temperature, through a capillary tube. Depending on the type of scales occurring in the experiments, several additives will be selected. Also, the effect of different additive concentrations will be investigated. In order to determine the corrosion rates, the gravimetric method will be used, both in static conditions and in dynamic conditions.