(1) University of Copenhagen, DK-1350 Copenhagen K, Denmark
(2) Geological Institute
Abstract: Shelf-edge deltas, slope gullies and base-of-slope massive sands, Upper Jurassic, East Greenland: Field analog for a complex type of reservoir
Shelf-edge sandbodies formed during major sea-level falls are important targets for hydrocarbon exploration. They are coarse-grained, commonly basinally-isolated, encased in outer shelf mudstones, strike parallel, and have sheet-like geometry. They form the source of sandy debris flows and turbidity currents which deposit thick massive sands at the base-of-slope.
The Upper Jurassic of East Greenland shows excellent exposures of a forestepping stack of shelf-edge deltas composed of high-angle clinoform-bedded coarse-grained sand. The clinobeds have an areal of extent of up to 900 km2 and are up to 50 m thick. Sandy debris flows were triggered from the collapsing delta front when the delta had prograded to the shelf-slope break. They flowed downslope through a network of gullies cut into the slope muds and deposited thick massive sands at the base-of-slope. Subsequent to burial the massive sands were liquefied and intruded into the mudstones forming an impressive intrusive complex. The mudstones have excellent source rock potential and the intrusive sandstones act as a drainage system for migrating hydrocarbons. The larger massive sand bodies are potential reservoirs and the intrusive complex could, in addition, act as a fairway for hydrocarbon migrating into the shallower shelf-edge delta sandstones.
The whole system provides an excellent field analog for several types of poorly understood fields in the North Sea and elsewhere.
AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana