Exploration for Natural Gas in Northern Germany and in the Alpine Area

Abstract

Abstract During the sixties, natural gas fields in carbonate reservoirs of the Sechstein formation (Upper Permian), in particular, were developed in the North German basin at depths of 2 000 - 4 000 m (about 6 500′ - 13 0001). Current exploration is focussed on Rotliegendes sandstones (Lower Permian) at about 5 000 m (16 400′). Successful discoveries are being developed. In some places natural gas has been discovered below the Permian in sandstones of the Upper Carboniferous (Pennsylvanian), the coalbearing source formation for the gas. With the development of gasbearing Paleozoic and deeply buried sandstones, the problems of tight reservoir rocks became evident. Stimulation of these rocks requires super-frac operations. Throughout the present phase of active development, exploration geologists have in mind that exploration in future decades will be looking out for potential natural gas prospects in Devonian and/or Lower Carboniferous (Mississippian) of the North German basin. This has already happened in the eastern part of Germany. Such targets occur at depths of about 7-8 000 m (23 000′ - 27 000′). Geophysical surveys and some wildcat drilling, partly supported by governmental funds, have been carried out, some of which by major joint ventures. Similar subsidies are given for exploration of deep targets (6 - 8 000 m, 20 - 27 000′) in the area of the Northern Alpine thrust zone in Bavaria. In the Northern Alpine Foreland, however, only small to medium natural gas fields at depths of between 1 000 and 3 000 m (About 3 000 - 10 000′) have so far been developed. Below the intermountane Alpine basins (Austria) and in the Southern Alpine Foreland (Italy) discoveries have been made at depths of up to 7 000 m (23 000′).