--> Abstract: Deep-Water Foraminifera and Petroleum Geology of the Oligocene Kugmallit Submarine Fan Complex in the Beaufort Sea, Arctic Can; #90063 (2007)

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Deep-Water Foraminifera and Petroleum Geology of the Oligocene Kugmallit Submarine Fan Complex in the Beaufort Sea, Arctic Canada

 

McNeil, D.H.1, J.R. Dietrich2, D.R. Issler2, J. Dixon1, K. Hu1 (1) Geological Survey of Canada, Calgary, AB (2) Geological Survey of Canada, Calgary,

 

Thirteen exploration wells have been drilled in the Kugmallit deep-water play of the Beaufort Sea resulting in six significant discoveries. Potential reserves are large - 2 billion barrels of oil and more than 30 TCF of natural gas, but the play has been delayed by a record of thin sandstones, discontinuous reservoirs on large shale-cored anticlines, and 50 to 100 meters of water, seasonally ice covered. New seismic data and the proposed Mackenzie Valley pipeline, however, now make this prospect more favourable. Nine of the wells penetrate the extensive Oligocene Kugmallit submarine fan complex deposited on the lower slope and continental rise. Deep-water agglutinated foraminifera occur abundantly in most of these deposits, dominated by Bathysiphon, Reticulophragmium, and Recurvoides. Some species, such as R. projectus occur only in the deep water facies, but many other species ranged onto the upper slope and outer shelf during the Oligocene. The “tops” for agglutinated species are diachronous and young distally. Sediment of the Kugmallit Sequence underwent rapid subsidence in the Late Cenozoic concurrent with deposition of the >2.5 km thick Pliocene-Pleistocene Iperk Sequence. As a result, all the reservoirs occur below the top of an overpressure zone located at the base of the Iperk. Thermal maturity, determined by foraminiferal colouration (FCI), is generally low through the Kugmallit fan deposits, but increases with present day borehole temperatures, for example 100oC=FCI 2.6 and 137oC=FCI 5.8. Evidence of hydrocarbon-related diagenesis, indicated by precipitation and dissolution of silica in agglutinated foraminifera, is present in two significant discovery wells.

 

AAPG Search and Discover Article #90063©2007 AAPG Annual Convention, Long Beach, California