The reserves of natural gas in Germany are limited. Hence, new exploration concepts are necessary to meet the future requirements. The BGR has studied in collaboration with German and European universities and the Germany oil industry the possibilities for deep gas generation in northern Germany. The term ‘deep gas’ defines natural gas generated from organic matter in pre-Westphalian Sediments. A multidisciplinary geological and geochemical approach has been followed in this research program: Structural geology of the pre-Permian and palaeogeographical studies of potential pre-Westphalian source rocks. Organo-petrographical studies in order to set up maturity maps of Base Zechstein and Top pre-Permain. Modelling of burial and subsidence. Source rocks evaluation including hydrous and anhydrous pyrolysis experiments. Extensive gas and isotope geochemistry on reservoir gases and pyrolysis products. The integration of all results verify that the prerequisites for the existence of deep gas in Germany are fulfilled in several cases and allow ‘perspective areas’ to be defined.
As a contribution to securing the mid and longterm domestic supply of natural gas, but also in the run-up to industrial exploration, the Federal Institute for Geosciences and Natural Resources (BGR), has being carrying out the interdisciplinary study ‘Deep Gas’ (Stahl et al. 1996).
The aim was to gain evidence for the existence of deep gases of pre-Westphalian origin, to narrow down their genetic origin, to estimate the timing of gas generation and to highlight the circumstances under which deep gases in the North German Basin can be expected.
DISTRIBUTION OF PRE-WESTPHALIAN SOURCE ROCKS Early Paleozoic source rocks and Devonian source rocks certainly play only a subordinate role in the North German Basin.
The source rock potential in the pre-Westphalian carboniferous Sediments however is extremely interesting, especially since the natural gas fields Altmark-Wustrow and Alfeld-Elze are situated outside the distribution of coal-bearing Westphalian.
In the Dinantian, coal-bearing delta-plain and lacustrine deposits as well as alternations of shallowmarine and deltaic deposits (Yoredale facies) with source rock potential are limited to the northern and north eastern fringe of the depositional area (Mid North Sea high, Ringköbing-Fyn high, Lublin area).
Intra-platform basins, known from Central Britain and containing marine and non-marine source rocks, may also occur in the southern North Sea basin and in the north German plains. South of the grabendissected carbonate platform the large, starved Rheno-Hercynian basin with marine source rocks (alum shales, silicious shales) extended from the Rhine to Upper Silesia.