The Impact of Conjugate Margins Analysis on Play Fairway Evaluation - An Analysis of the Hydrocarbon Potential of Nova Scotia "Best of EAGE"

Luheshi, Matt ¹; Roberts, David G.¹; Wilson, Hamish ¹; Nunn, Keith R.¹
(1)RPS Energy Ltd., London, United Kingdom.

An understanding of the rift history of rifting margins is fundamental to developing prospectivity. A new analysis of the rifting history of the Central Atlantic with particular focus on Nova Scotia and Morocco shows the possibility of new play systems.The revised rift model is based on acquisition of new refraction data, reprocessing of existing refraction and multi-channel seismic as well as integration of potential fields data from the Nova Scotia/Morocco conjugate margins. The new analysis of rifting history integrated with a play fairway exploration evaluation has identified some potentially important new play types.

The use of conjugate margin models in combination with a systematic play based exploration approach has proved critical in developing models on which the hydrocarbon prospectivity can be quantified and de-risked. The fundamental starting point is a thorough review of the rifting history of the Central Atlantic. This was conducted using an integrated plate tectonics project supported with extensive forward structural modelling.

Previous interpretations of the available data offshore Nova Scotia have proposed an apparent along strike transition from a volcanic (or magmatic) passive margin to a non magmatic passive margin. Review of these historical data sets with new data acquired as part of this project leads to a revised interpretation. The proposition here is that the whole of the Nova Scotian margin is volcanic. This leads to a profoundly different view of the evolution of paleo-water depths and implies the existence of a regional restricted shallow marine environment in the Early Jurassic. Such an anoxic environment would be consistent with the presence of a rich regional Early Jurassic source rock evidenced from geochemical analyses of source rocks and discovered oils.

The paper will show the development of play models at both Jurassic and Cretaceous levels based on the above fundamental re-analysis of the Scotian margin’s rift history. A number of plays will be shown, including Jurassic carbonates, delta and deep marine reservoir systems, sourced locally or from deeper syn/post rift lacustrine/restricted marine sediments. Extensive large-scale salt related structures show the potential of a high value petroleum province on both sides of the Atlantic. The play evaluations are based on a rigorous understanding of sequence stratigraphy built on existing and new biostratigraphic and seismic stratigraphic studies.

AAPG Search and Discovery Article #90135©2011 AAPG International Conference and Exhibition, Milan, Italy, 23-26 October 2011.