Carl F. Gyllenhammar¹
(1) University of Durham, Durham, United Kingdom

Abstract: Subglacial groundwater flow during the last glaciation in the North Sea

Several recent published studies of hydrocarbon maturation and filling history of North Sea fields have emphasised the importance of the recent geological history. In the North Sea, the Quaternary epoch has not been regarded as particularly relevant to petroleum geology, although the Quaternary epoch was a period of giant ice sheets. The lithosphere underlying the Fennoscandian shield was depressed several 100 meters during the last glaciation (Weichselian/Devensian) followed by its current rebound. The overburden pressure from the ice sheets have been used in this paper to model not only the subsidence and uplift (rebound) but also the effects of the ice loading on sediment properties (compaction and pore fluid pressures). Modelling focuses on the elevation of pore pressure during loading and its dissipation via regionally extensive sandstones aquifers. In addition the potential influence of hydrocarbon maturation and migration are considered.

The British Geological Survey has over several decades cored 576 sites in the offshore area of the British Islands. The geotechnical results from several of these sites suggest current overconsolidation consistent with the modelling of ice iceloading. the results have also been evaluated to investigate subglacial groundwater flow during the last glaciation of the North Sea.

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana