Reifenstuhl, Rocky R.1
(1) Alaska Division of Geological & Geophysical Surveys, Fairbanks, AK
ABSTRACT: Reservoir Characterization Studies: Yukon Flats Basin, Alaska
A reservoir characterization study by the Alaska Division of Geological and Geophysical Surveys (DGGS) and U.S. Geological Survey took place in 2002. Potential reservoirs are quantified using petrophysics (P&P) and detailed petrographic analyses (point counting, grain size measurement, cement timing assessment). Other geologic controls include: facies analyses, stratigraphic sections, regional facies correlation, distribution, and subsurface and surface geology. To evaluate principle target reservoirs, data are integrated with the results of our reconnaissance geology. The Yukon Flats basin is a latest Cretaceous and Cenozoic extensional sedimentary basin associated with the Tintina and Kaltag strike-slip faults. More than 15,000 feet of nonmarine and lake sediments are inferred from geophysics. Lake sediments may include oil-prone or gas-prone organic material and act as reservoir topseals. Oil and gas plays include reservoir sandstones in structural and stratigraphic traps. Existing gravity data indicates a 50 milligal low over the south-central portion of the basin. At the town of Fort Yukon, the U.S. Geological Survey in 1994 drilled to 390 meters deep. The stratigraphy included 7 to 9 meters of lignite coal (with gas) of Miocene age at 370 to 390 meters depth. Tasmanite oil shale (Triassic to Permian) occurs locally (Tozitna terrane). The Mesozoic and Paleozoic age Tozitna terrane underlies an unknown part of the Yukon Flats basin. Potential energy resources of the Yukon Flats basin include: coalbed gas, shalebed methane, conventional gas, and oil. Porosity and permeability values from the Yukon Flats basin samples (40) range from 0.006 to 38.7%; 0.001 to 203mD.
AAPG Search and Discovery Article #90026©2004 AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.