South Dinkum Prospect: A Potential Giant?

Arnaud Lenail, Baljit Dhami, Patrick Chaffel, and James Matthews
Total, Paris - La Défense, France.

The South Dinkum leases are located in the Flaxman Island zone, 50 kilometres from shore in approximately 35m of water depth. These leases were awarded to Total (100% W.I.) in the 2007 Beaufort Sea 202 Lease Sale for a period of 10 years.

The regional geology of the North Slope of Alaska has been extensively studied since the discovery of Prudhoe Bay and neighbouring fields. The prospectivity of the South Dinkum area has been recently re-evaluated based primarily on an extensive set of non-exclusive 2D seismic surveys shot in the eighties and re-processed in 2010.

The main petroleum objective on South Dinkum area corresponds to the Triassic sandstone of the Ivishak formation, which is the main reservoir at the Prudhoe Bay super-giant field. Overlying shales of the Shublik formation constitute an excellent source-rock but also an efficient seal. Trapping is defined as tilted fault blocks generated during the Beaufortian rifting phase. Recent diagenesis modelling confirms that good porosity preservation at deep burial is possible in the context of South Dinkum, partly due to the specific mineralogy of the Ivishak fluvial sands and to the likely early charge of hydrocarbons. The interpretation of the reprocessed data has identified a giant undrilled structure called the South Dinkum prospect

In addition to the Trias, a shallow Oligocene play is proven in the area (Hammerhead and Sivulliq discoveries) and is mapped to extend onto the South Dinkum blocks. The play consists in stacked shelfal deposits sourced by the well-known Pebble Shale unit but also by widely deposited shales of the Torok/Canning formations. Presence of hydrocarbon accumulations is inferred by possible DHI’s seen on seismic, and this Tertiary play, despite being smaller in size, provides a significant upside to the South Dinkum blocks.

Several subsurface and Surface challenges are associated to the South Dinkum prospect, but it has been confirmed from the recent seismic processing and reservoir modelling that it could be a giant, with a combined mean resource potential of greater than 1 Billion barrels of condensate and 5 Tcf gas. South Dinkum thus consists of what is most likely to be the largest undrilled feature in the area, and could hence be the next frontier to explore in the offshore Beaufort Sea.

 

AAPG Search and Discovery Article #90130©2011 3P Arctic, The Polar Petroleum Potential Conference & Exhibition, Halifax, Nova Scotia, Canada, 30 August-2 September, 2011.

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