Frontier Sub-basalt Exploration in the North Atlantic

Gregers Dam, Michael Larsen, Thomas Ottesen, and Niels Westphal
DongEnergy, Hørsholm, Denmark

In recent years, frontier exploration in the North Atlantic has moved into basalt-covered areas. Although advances in seismic acquisition and processing methods have improved sub-basalt imaging, good analogues are still very important in evaluating the exploration potential in these areas.
The Kangerlussuaq Basin, East Greenland, and the Nuussuaq Basin, West Greenland, are both onshore basalt-covered basins. These basins have a very similar geological evolution and reveal the complex interplay between magmatic processes and sedimentation. Detailed fieldwork has identified three sub-basalt and intra-basalt plays (Mid-Cretaceous, Maastrichtian-Danian and Late Paleocene-Eocene) that can be extended into the offshore basins. The reservoirs of the Mid-Cretaceous and Maastrichtian-Danian Plays are shallow to deep-marine sandstones sealed by deep-marine mudstones. Fluvial and shallow marine sandstones interbedded with volcanic rocks form the reservoir of the Late Paleocene-Eocene Play.
A Late Jurassic source rock has been proven in the West of Shetland area, whereas the geochemical analysis of widepread oil seepage onshore in the Nuussuaq Basin have demonstrated the presence of Early Paleocene and pre-Late Cretaceous source rocks.
Emplacement of hot magmatic bodies at depth followed by extrusion of thick lavapiles impacts the entire sub-basalt petroleum system. In West Greenland magmatic-driven processes controlled sand distribution systems and probably also source rock maturation.
In both East and West Greenland, interbedded volcanic and siliciclastic depositional systems form a direct analogue to a series of hydrocarbon bearing sandstones within a thick volcanic sequence of Paleocene age proven by a recent discovery well in the West of Shetland area (well 213/27-1z operated by Chevron). Also offshore West Greenland the play models established on the basis of onshore analogues has successfully been used in the most recent licensing round.

AAPG Search and Discovery Article #90072 © 2007 AAPG and AAPG European Region Conference, Athens, Greece