Summary

Oil shales are recorded around the world, in Cambrian to Tertiary stratigraphy, and in a range of depositional environments, which directly impacts organic content and subsequent oil yield, making regional geology a key control on economics. Specifically an understanding of the distribution of organic matter and brittle grains (or mineral matter) within a sequence stratigraphic framework is vital, along with consideration of the regional stress regime and thermal maturity. This can only be achieved through an improved understanding of the subsurface regional geology and stratigraphic context. While exploration has yet to start in earnest in the Karoo Basin, and although it is further developed in the Parana Basin, lessons can still be learnt from US resource play analogues, as well as the world class Eocene Green River play in Wyoming and Utah.

Introduction

The lack of a comprehensive study on global oil shale distribution and no conclusive classification of this resource can make comparisons difficult. The application of our biostratigraphically calibrated, global, 3rd-order sequence stratigraphic Earth Model to these oil shale horizons helps constrain and predict regional lithological variation. It also reveals that similar genetic patterns and cyclicity can be seen in the Cisuralian oil shale targets of the Whitehill and IratÍ formations, regardless of differing tectonic settings and sediment supply histories; highlighting the eustatic nature of these formations. Such a sequence stratigraphic approach can ultimately provide a basis for genetically subdividing an oil shale horizon across a basin and down to individual system tracts.

URTeC 1575989

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