--> Abstract: Beaufort-Mackenzie Basin Offshore Shelf and Slope: Vast, Mostly Untested, Potential of Oligocene and Younger Sequences, by Peter A. Emmet, Naresh Kumar, James A. Helwig, and Menno Dinkelman; #90124 (2011)

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Making the Next Giant Leap in Geosciences
April 10-13, 2011, Houston, Texas, USA

Beaufort-Mackenzie Basin Offshore Shelf and Slope: Vast, Mostly Untested, Potential of Oligocene and Younger Sequences

Peter A. Emmet1; Naresh Kumar1; James A. Helwig1; Menno Dinkelman2

(1) ION BasinSPAN Programs, Houston, TX.

(2) Chief Geologist, ION Geophysical - GXT, Houston, TX.

The Beaufort-Mackenzie-Banks Island areas of the Canadian Arctic margin are host to an active petroleum system. The Mackenzie delta is potentially second only to the Mississippi delta in size and significance as a hydrocarbon exploration province in North America. Exploration has yielded > 50 significant discoveries containing > 1.1 BB bbls (173 MM m3) of recoverable liquids without yet testing water depths > 50m. Leases recently acquired in 500 to 1,000 m water depth suggest that the industry expects to meet the technical challenges of drilling in deeper water. Prestack Depth-Migrated (PSDM) 2D regional seismic lines document structural and stratigraphic controls on source, migration and trap for a variety of plays. We focus on the four youngest, as yet mostly-untested, sedimentary sequences that generally post-date formation of the Beaufort Fold Belt. The Plio-Pleistocene Iperk deltaic sequence spans shallow to deep-water environments and exceeds 3,000 m thickness over an area greater than 24,000 km 2. The locus of deposition is 150 km north of the Tuktoyaktuk peninsula. The shallow-water plays are sand-prone deltaic shelf and shelf margin strata, and deep-water plays include basin floor fans, slope fans, channel levee and slump deposits that may be draped over local structures. Deposition of the thick Iperk accelerated maturation of older sequences. The base of the Iperk sequence is in attainable drilling depths even at deep water drilling locations. The Upper Miocene Akpak and Lower Miocene Mackenzie Bay sequences are locally sand-prone, strongly progradational, shallow-water strata. The two sequences attain a combined thickness > 1,000 m over an area > 50,000 km 2. For comparison this area is equivalent to all offshore Texas OCS blocks in water depths < 200 m. The Akpak and Mackenzie Bay sequences are particularly thick (1,000 to 3,000 m) in growth synclines in the central part of the Beaufort fold belt 100 km north of Herschel Island. These sequences onlap a late structural feature, the Tulluk High, which was uplifted in Miocene time. The Oligocene Kugmallit sequence generally fines-upward and fills depositional topography across the fold belt. It attains a thickness > 1,000m over an area of 20,000 km 2, with exceptional thickness (> 4,500 m) in tilted fault blocks in a pull-apart basin 100 km north of the Tuktoyaktuk peninsula. Three of the five largest discoveries to date in this basin are reservoired in the Kugmallit sequence.