Sequence
Stratigraphic
Analysis
of the Kuparuk River Field:
Implications for Kemik Exploration on the North Slope of Alaska
A. D. Donovan, D. J. Bouquet, P. E. Walker, L. M. Dobson,
and M. D. Sullivan
A detailed sequence
stratigraphic
analysis
of the Kuparuk River Field on the
North Slope of Alaska reveals that the distribution, thickness, and facies
variations of the Early Cretaceous Kuparuk A and Kemik (Kuparuk C) reservoirs
are controlled by the primary depositional paleogeography of these units, as
well
as their post-depositional erosion and accommodation patterns. The Kemik
stratigraphic interval at the Kuparuk River Field is an unconformity-bounded
depositional
sequence
. This
sequence
consists of a basal aggradational to
retrogradational portion, interpreted as the lowstand and transgressive systems
tracts, overlain by a progradational portion interpreted as a highstand systems
tract. The distribution and thickness of the underlying Kuparuk A reservoirs are
also effected by the Base and Top Kemik unconformities, as
well
as by four
unconformities located within and at the top of the Kuparuk A.
Within this sequence
stratigraphic framework, Kuparuk A and Kemik reservoirs
are interpreted as erosional remnants of, what were originally, more laterally
continuous highstand and transgressive shorelines, and lowstand incised valley
systems. Kemik and Kuparuk strata were preserved in paleo-structural lows and
eroded over paleo-structural highs formed during Early Cretaceous deformation.
This syn-rift deformation coincided with the development of the base Kemik and
top Kemik unconformities.
Sequence
-keyed paleogeographic maps across the Kuparuk
River Field, reveal that: 1) Kemik highstands were deposited along an
arcuate-shaped, low-energy, wave-dominated shoreline which, in general, becomes
more proximal to southwest and more distal to the northeast; 2) Kemik incised
valleys (lowstands) trend, in general, NE-SW and thicken to the northeast; and
3) Kuparuk A reservoirs, unlike the Kemik, prograded and were derived from the
north.
AAPG Search and Discover Article #91019©1996 AAPG Convention and Exhibition 19-22 May 1996, San Diego, California