Global Palaeogeography and Palaeo-Earth Systems in the Modelling of Source Rock Depositional Space and the Predictive Mapping of Source Quality: Regional Examples from East Africa and Atlantic Ocean Margin Basins

Harris, Jim; Anderson, Edward; Adriasola Munoz, Alberto; Crossley, Rob; Glover, Claire; Hoyle, Jenny; Stronach, Nick; Watkins, Carl; Watson, John; Goodrich, Mike; Valdes, Paul; Proctor, Roger

The distribution of source rocks and the lateral variation in source quality are some of the main uncertainties for exploration in frontier basins. This information is also required for the assessment of potential shale gas and shale oil resources. To construct a predictive tool designed to address these problems global Plate Wizard reconstructions were used as the basis for palaeogeographic mapping. Detailed palaeotectonics and palaeoenvironments maps were prepared and a new method relating topography and bathymetry to plate tectonic environments was used in the construction of palaeo digital elevation models (DEMs) The compilation of the base maps is based on a global database of palaeoenvironmental and lithofacies data, the legacy of over 30 years of petroleum geological studies and an equally extensive source rocks database. The palaeogeographies were coupled with state-of-the-art palaeo-Earth systems models (HadCM3 palaeoclimate model) and a barotropic model to simulate palaeotides. The database also includes climate proxies that were used to test the veracity of Earth systems modelling results. Together the maps and model results were used to define source facies depositional space and to create a new predictive methodology based on the modelling of organic matter productivity, dilution and preservation parameters. Predictive mapping is used here to provide an assessment of source rock risk for key time slices and to provide petroleum play concepts for selected East Africa and Atlantic Ocean margin basins. This combined approach provides an understanding of regional palaeogeographic and palaeoclimatic geohistory, drainage basin evolution, and the estimation of clastic sediment flux. The gridded model results provide an objective assessment of lateral variability in source quality that is also applicable in the estimation of unconventional resources.

AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013