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

Abstract

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 collection 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, will be used diagrams calculated by the AqQa program. Then by the use of Giggenbach and Arnorsson triangular diagram we will have information regarding water-rock equilibrium. The chemical geothermometers constitute 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 have been recorded scaling problems, metallic coupons will be installed into a laboratory set up, geothermal water from the well being kept at certain temperature for different periods and samples 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, at wellhead temperature and later at lower temperature, through a capillary tube. Depending on the type of scales occurring in the experiments, several additives will be selected, and there will be tried out different concentration ranges of the additives. In order to determine the corrosion rates, there will be used gravimetric method, in static conditions and also in dynamic conditions.