Possible Hydrocarbon Habitat of the Bulge, Alaska and Yukon Territory

BANET, ARTHUR C., JR., U.S. Bureau of Land Management, Anchorage, AK

Bedrock geology of the northernmost Bulge of the Rocky Mountain Cordillera consists of units ranging in age from the Proterozoic to the Recent. Concerted LANDSAT imagery, field mapping, and CDP seismic interpretation indicates that there are several thick, unconformity-bounded and areally distinct depositional megasequences in northern Alaska and Yukon Territory.

Analyses of the Arctic National Wildlife Refuge (ANWR), 1002 area, subsurface suggest the presence of several large structures. However, seismic resolution is insufficient to determine the stratigraphy with a high degree of confidence. The oldest sediments in the Bulge are the northerly derived Katakturuk dolomite and the southerly derived, predominantly clastic Neruokpuk Formation. Tests of these units

immediately outside ANWR produced oil, gas, and water from vugs and fractures.

Both the Katakturuk and the Neruokpuk are overlain by dissimilar but thick and areally limited Cambrian-Devonian sediments with undetermined reservoir potential. Middle and Upper Ellesmerian (Endicott, Lisburne, and Sadlerochit Groups; the Prudhoe reservoirs) crop out around the periphery of the coastal plain and are found in the subsurface. Their presence and reservoir development in the structures of the 1002 area depend upon the extent of Lower Cretaceous truncation. Two dissimilar locally derived breakup megasequence sandstones having limited lateral extents overlie older units. They have increasing regional importance as commercial oil and gas reservoirs.

Very thick, southerly derived, Brookian clastics overstep this area. They contain the largest endowment of the in-place hydrocarbons in Alaska and the Yukon. Their commercial development is incipient.

AAPG Search and Discovery Article #91004 © 1991 AAPG Annual Convention Dallas, Texas, April 7-10, 1991 (2009)