’NW European Gas Atlas’ – new implications for the Carboniferous gas plays in the western part of the Southern Permian Basin

The ‘Northwest European Gas Atlas’ comprises maps on characteristics (e.g. molecular and isotopic compositions) of natural gases in northwest European gas fields, on the distribution and facies of source and reservoir rocks, on maturities, and other relevant geological information. The mapped area includes the entire Southern Permian Basin from the Southern North Sea to central Poland. Palaeozoic source rocks in the Dinantian, Namurian and Westphalian have been identified in the western part of the Southern Permian Basin. They contain kerogens of marine (Type I and II) and continental origin with TOC contents as high as 12%. There are two Carboniferous production provinces in this area: C1 in the Southern North Sea and C2 in the area along the border between The Netherlands and Germany. The natural gas in most of the C1 production province has methane contents of more than 80%; in most of the C2 province even more than 85%. Nitrogen is the second most abundant constituent in both provinces. Carbon dioxide plays a significant role only locally in the areas of intrusive rocks. Isotope data show that the source of the natural gases in the C2 province is a terrestrial rock (Westphalian). In the C1 province, the gases are of mixed origin: a low maturity terrestrial source rock (Westphalian) and a more mature marine source rock (?Namurian).