AAPG Middle East Region Geoscience Technology Workshop, Rift Basin Evolution and Exploration

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From Geomodel to Basin Model to Reality - An Integrated Approach to Petroleum Systems on Rifted Margins

Abstract

Self-evidently the development of ‘Atlantic’ style passive continental margins, and by extension the petroleum systems contained within them, is a consequence of a complex interaction of a large number of processes including crustal tectonics, mantle dynamics, climate, stratigraphy, eustacy, paleogeography, ocean currents. Yet, many studies still tend to compartmentalise basin evolution into its constituent parts (e.g. lithospheric stretching processes, eustatic controls on stratigraphic stacking architectures); the inter-related nature of these processes is overlooked. This provides significant problems when geomodels are used as the input for Petroleum Systems Models (PSM) as the parameters tend to be relatively simplistic representations of the complexity and dynamic evolution of margins. In some situations, this is not important as there are substantial, and well calibrated, data to constrain the model. In frontier exploration areas where there are very limited or no calibration data this presents a significant limitation in assessing the applicability of the PSM. This study focusses on integrating across the range of processes that are associated with the development of rift basins and passive margins to develop a better understanding of the evolution, and petroleum implications, of lithospheric stretching from rift to mature margin. Questions that we are currently considering include the role of rift inheritance on margin development; the nature of the transition from rift to drift and the role of volcanics; controls on post rift margin deformation. These play a critical role on predicting heat flow and basin fill within these systems. The implications for the hydrocarbon system on the margins will also be discussed along with recent results that highlight the importance of considering all of these processes when undertaking petroleum systems modelling. In addition, there will be a focus on how to apply sensitivity analysis on these inputs to determine where the greatest, and most important, uncertainty occurs. The study will consider a range of basin types including magmatic and non-magmatic margins using examples at basin and reservoir scale from a variety of frontier basins including Orange Basin of Namibia and South Africa, East Africa Rift, Kenya, Somalia, West of Shetlands and Greenland.