Print this pagePetroleum Systems of the Alaskan North Slope—A Progress Report
By
L.B. Magoon, P.G. Lillis, K.J. Bird (U.S. Geological Survey), and C. Lampe (IES, Integrated Exploration Systems)
Seven onshore
North Slope petroleum systems are identified and mapped using 
oil
-to-oil and
oil-to-source rock correlations, pods of active source rock, and overburden rock
packages. In mapping these systems, we assumed that: a) a source rock contains
at least 2 wt. % organic carbon (TOC); b) an immature oil-prone source rock has
a hydrogen index (HI) greater than 300 (mg HC/gm TOC); c) the top and bottom of
the petroleum (oil plus gas) window are marked by vitrinite reflectance values
of 0.6% Ro and 1.0% Ro, respectively; and d) most hydrocarbons are expelled
within the petroleum window.
Three overburden rock packages determined the time of
expulsion and geometry of migration paths: a) a southern package of Early
Cretaceous and older rocks structurally-thickened by early Brooks Range
thrusting; b) a western package of Early Cretaceous rocks that filled the
western part of the foreland basin; and c) an eastern package of Late Cretaceous
and Paleogene rocks that filled the eastern part of the foreland basin.
The seven petroleum systems mapped by us include: a)
a southern system involving source rock in the Kuna and Otuk Formations that was
active during the Late Jurassic and Early Cretaceous; b) three western systems
involving source rock in the Shublik Formation, Kingak Shale, and Hue Shale that
were active during the Albian; and c) three eastern systems involving the same
three source rocks that were active during the Paleogene.
AAPG Search and Discovery Article #90008©2002 AAPG Pacific Section/SPE Western Region Joint Conference of Geoscientists and Petroleum Engineers, Anchorage, Alaska, May 18–23, 2002.
