Palaeozoic natural gas in Mesozoic North German oilfields – a remarkable observation
Gerling, Johannes Peter; Blumenberg, Martin; Faber, Eckhard; Stahl, Wolfgang
published: Sep 1, 2016
ArtNo. ESP171016702020, Price: 29.00 €
Franz Kockel has been significantly involved, when BGR performed elaborate investigations in the late 1980s on the petroleum systems existing in the Lower Saxony Basin (LSB). In this paper, focus is placed on geochemical data of oil-associated gases from oilfields with striking properties. Compositions of gaseous hydrocarbons as well as stable isotope ratios clearly indicate that natural gas from subjacent Upper Carboniferous coals is abundantly admixed with the common oil-associated gases in several oilfields in the LSB. The Vorhop oilfield is a particularly well studied reservoir. Here, in addition to carbon gas geochemistry, nitrogen abundances and stable isotope signatures are studied and are equally a clear indicator for the feeding of coal gas into a certain part of the oilfield. In all other oilfields presented in this paper, salt tectonics and/or deep reaching fault systems, the latter in some cases re-activated during the inversion of the LSB, are supposed to provide migration pathways for natural gas originating from deep strata. Physical reservoir data are in accordance with our assessment that this mechanism may still be active and can be considered in future exploitation strategies.