Upper Jurassic Petroleum Systems of the Arctic Investigated by Earth System Models

Balazs Badics
Global Exploration, StatoilHydro, Stavanger, Norway.

The main objective of Earth System Modelling is to reduce the risks of petroleum exploration by predicting the most likely distribution of source, reservoir and seal rocks at selected time-slices in Earth history in a dynamic matter.

The modelling results can be a series of palaeogeography-based predictive maps which can easily be integrated with other geological information to define proven as well as potential petroleum systems. The lecture will describe Earth System modelling of late Jurassic source rocks in the Arctic as well as the tests made on the model predictions.

All geologic models require calibration. 3D basin models are calibrated using temperature and vitrinite reflectance datasets. Validating Earth System Model results is more challenging and requires innovative approaches. Climate predictions can be compared with climate-indicator sediments and fossils. Predicted lithology distributions can be evaluated against observed data in wells and outcrops. Fixing the time interval being assessed and the necessity of a coarse resolution in global models (grid-size of several 100 km) also represent key challenges for calibration.

The extent and depositional setting of source rocks and working petroleum systems of the upper Jurassic in the Arctic region has been investigated to calibrate and build the Earth System Model. The dataset included the observed thickness, extent, organic matter content and sedimentation rate of the known source rocks in East Greenland (Hareelv Fm.), the Norwegian Sea (Spekk Fm.), the Norwegian Barents Sea (Hekkingen Fm.), West Siberia (Bazhenov Fm.), the North Slope of Alaska (Kingak Fm.), the Mackenzie Delta (Husky Fm.) and the Sverdrup Basin (Ringnes Formation).

The Earth System Model predicted the overall areal extent of all known Upper Jurassic source rocks, and revealed the role of sedimentation rate in source rock prediction. The model suggests that good-quality; oil-prone source rocks occur only if the sedimentation rate is low enough to preserve adequate organic richness. With higher sedimentation rate the impact of dilution decreases source rock quality.

The extension of known petroleum systems into new areas, as well as the potential for new petroleum systems in frontier basins can be assessed using Earth System Model results. A detailed verification of such source rock predictions is always required before one can use the results to identify new petroleum systems.

AAPG Search and Discover Article #90096©2009 AAPG 3-P Arctic Conference and Exhibition, Moscow, Russia