SCHENK, C. J.¹, D. W. HOUSEKNECHT², P. H. NELSON¹, R. C. BURRUSS², and K. J. BIRD^3
1U.S. Geological Survey, Denver, CO
²U.S. Geological Survey, Reston, VA
³U.S. Geological Survey, Menlo Park, CA

Abstract: Reservoir Properties And Sedimentology Of Some Potential Reservoir Sandstones In The National Petroleum Reserve Alaska (NPRA)

The recent discovery of Alpine field and the upcoming Federal lease sale in NPRA have focused attention on the potential for sandstone reservoirs in Jurassic through Lower Cretaceous strata. Analysis of cores and logs from wells within and near NPRA suggests that reservoir prediction will largely depend upon our understanding of sequence stratigraphic relationships. Reservoir quality sandstones in the basal part of the Lower Cretaceous pebble shale unit with porosity and permeability in excess of 20% and 100 md, respectively, were deposited in topographic lows on the Lower Cretaceous unconformity, either as lowstand or transgressive sands. These thin sandstones, including the Walakpa sandstone, are coeval with the Kuparuk "C" sandstones that are productive east of NPRA. Several sandstones within the Jurassic Kingak Shale in NPRA, such as the Simpson interval, with porosities in excess of 20% but with permeabilities rarely above 1 md, represent muddy glauconitic sandstones deposited mainly as parts of coarsening upwards, highstand shelf parasequences. Potential reservoir sands may occur where these muddy highstand sands were reworked during lowstand or transgressive events, as interpreted from Jurassic sandstones in the area immediately northeast of NPRA.

AAPG Search and Discovery Article #90928©1999 AAPG Annual Convention, San Antonio, Texas