61 technical article © 2012 EAGE www.firstbreak.org first break volume 30, January 2012 The impact of conjugate margins analysis on play fairway evaluation – an analysis of the hydrocarbon potential of Nova Scotia Matt Luheshi, 1* David G. Roberts, 1,2 Keith Nunn, 1 Jannis Makris, 3 Bernard Colletta, 4 Hamish Wilson, 1 Frederic Monnier, 4 Guillaume Rabary 4 and Matthieu Dubille 4 Introduction Analysing conjugate margins is a powerful way of evaluat- ing basins in a search for overlooked plays. Emerging new plays in Brazil (subsalt), Ghana (Cretaceous), and Morocco (Jurassic and Cretaceous) have triggered interest in search- ing for analogue plays in their respective conjugate mar- gins. Interest in the continental margins of Nova Scotia and Morocco has been enhanced by recent licence activity. Both margins show evidence for elements of working petroleum systems.  Proving an extensive and effective source system is essential to the hydrocarbon prospectivity of both margins.  Extensive shows, commercial discoveries, and evidence of by-passed oil demonstrate that there are effective charge systems. Here we describe forensic geochemical work that has been used to type the shows and link the fluids to specific sources. Traditional models for sourcing both margins have relied on Late Jurassic and Early Cretaceous delta systems.  However, these deltaic source rocks are restricted geographi- cally offshore Nova Scotia, and in the south-western half of the margin are too shallow to be effective, even where they are present. A search for more geographically extensive play systems requires more regional source rocks. We postulate that there may be a deeper source in the Early Jurassic, which may be effective in the south-west part of the Scotia margin and which could provide charge with different characteristics and timing. A revised rifting model of the central North Atlantic has been developed and is discussed below. It is based on integra- tion of new seismic refraction data acquired in 2009 and merged potential field data from both margins. It explains the relationship between salt deposition and restricted shal- low marine environments. The second critical risk has been reservoir prediction. New progress on this front is based on revised sequence and seismic stratigraphy. Reservoirs are found in Late Jurassic and Early Cretaceous delta systems with associated slope turbidites, and in the Jurassic carbonate bank. Play fairway analysis programme This study is based on a comprehensive, integrated play fair- way evaluation. The objective was to re-evaluate the hydro- carbon prospectivity offshore Nova Scotia. Exploration in Nova Scotia started in 1959 and ~2.1 bboe of hydrocarbons in place have been discovered from 127 exploration wells Abstract An analysis of the rifting history of the Central Atlantic focused on Nova Scotia and Morocco reveals new plays potentially charged from an Early Jurassic source system. The revised rift model is based on newly acquired seismic refraction data, reprocessing of existing refraction and multi-channel seismic data, and integration of potential fields data from the conju- gate margins. We infer from the geophysical evidence that there was volcanic rifting from south-west Nova Scotia to the Newfoundland fracture zone during the Early Jurassic, with a restricted, shallow marine environment for sediment deposi- tion. We have integrated plate tectonics, geochemistry, and sequence stratigraphic interpretation with the aim of identifying new plays. Analysis and integration of geochemical evidence has led to a new paradigm for the exploration potential offshore Nova Scotia. In particular, there is now good evidence for deposition of a source rock in restricted marine conditions during the Early Jurassic. This source rock is capable of providing charge to an oil play in the south-western half of the Scotian margin, which is a new concept for this area. 1 RPS Energy, 1 st Floor, Cottons Centre, Cottons Lane, London SE1 2QG, UK. 2 Department of Earth Sciences, Royal Holloway, Egham, Surrey, UK. 3 GeoPro GmbH, Billhorner Röhrendamm 8, 20539 Hamburg, Germany. 4 Beicip-Franlab, 232, Av. Napoléon Bonaparte, 92502 Rueil-Malmaison Cedex, France. * Corresponding author, E-mail: matt.luheshi@btinternet.com