Log Analysis of the Aurora 890 #1 OCS-Y-0943 Well, Offshore of the Arctic National Wildlife Refuge 1002 Area, Northeast Alaska

The Aurora well, drilled in federal waters immediately offshore of the Arctic National Wildlife Refuge, 1002 area, is currently the deepest well in the Beaufort Sea (U.S.). It represents some of the most recent publicly available geological data for this remote, but important area to U.S. and Canadian exploration. Geophysical logs record 18,325 feet (5587m) of elastic section at this location. Log analyses determines that both Breakup and Brookian depositional sequences are represented. Informal names are assigned to several sandstones to facilitate comparisons to regional units.

Breakup sequence shales and locally deposited sands are from 18,325 to 15,937 feet (5585 to 4858m). The basal Unit I, is approximately 1000 feet (305 m) of Kingak Shale and is terminated by a lower Cretaceous-age unconformity (LCU). It is unconformably overlain by Unit II: a coarsening and thickening upwards sequence of shales arid sandstones, culminating with the informally- named Tapkaurak sand. Unit III is mostly marine mudstone and is terminated by a lower Tertiary-age unconformity (LTU) at 15,937 feet (4858m). Notable similarities and differences exist between these sediments and coeval onshore lithologies and there are important implications pertinent to the analysis of the ANWR 1002 area.

This analysis identifies 10 units of middle Brookian and one upper Brookian sequence sediments. Individually, these units range in thickness from 473 to 3533 feet (144 to 1077 m) and are composed of mostly thin, and interbedded shale siltstone, mudstone and clay. Sediment transport directions are north to north-northwest. The major Brookian sequence sand, informally named the Oruktalik sand, had a show of gas and some minor staining, and is comparable to the Flaxman sands.