Abstract
More than 750 wildcat wells have been drilled in the Norwegian North Sea since 1966. Some of these wells could pose a risk for the environment, climate, and future CO(2) and hydrogen storage projects by being potential leakage pathways for subsurface gases (mainly CH(4) and stored CO(2) and hydrogen). To ensure well integrity, these wells were secured by building cement plugs at crucial positions in the well path before abandoning the well. However, first 2004 the NORSOK d-010 standard defined strict regulation for plugging and abandonment (P&A) of gas and oil wells along the Norwegian continental margin. Here we report data relevant for the quality of a P&A work done on old exploration wells (1979 to 2003) from the Troll gas and oil field in the Norwegian North Sea. The data was extracted from public available well completion reports and the webpage of the Norwegian Petroleum Directorate. The dataset was analysed regarding their availability, plausibility and evaluated towards the present P&A regulations for offshore Norway. Based on twelve single criteria a final P&A score for 31 exploration wells was established, which may be applied to other abandoned wells in the Norwegian North Sea for further analyses. The resulting scores vary from -1 to 23.67 whereby lowest scores indicate wells where monitoring would be recommended. A P&A work evaluation is especially relevant in the Troll area as Norwegian large-scale CO(2) storage is planned close to this location.