Limescale is a well-known term, since it occurs everywhere, where water is processed, i.e. water is heated up or evaporated. It precipitates out of hard water, whereas carbon dioxide outgases leading to formation of insoluble calciumcarbonate. In the oilfield industry, problems with scale precipitations cause a loss of billions of US dollars every year. Scale is a problem, since the production of hydrocarbons is connected with a series of temperature and pressure changes, which can initiate and/or aggravate the formation of scale. Precipitations can lead to a production loss, since the effective line diameter in general is reduced and thus reducing the production rate. The first part of the thesis describes the theoretical background. Therefore, this part includes explanations concerning the scale formation, the resulting possible problems due to scale precipitations and the methods for removing and avoiding the precipitations respectively. In the second part laboratory experiments are used to identify the best and most efficient products among a number of different scale inhibitors from a Global Tender, based on a screening procedure from OMV. Subsequent to the dynamic tests, predictions of possible precipitations should be done with a scale prediction software for comparison with the results from the practical tests. At the end two scale inhibitors could be identified, which showed very good results when testing with the four different water samples.