David W. Bowen1, Paul Weimer2, Andrew Pulham3
(1) Energy Minerals and Applied Research Center, University of Colorado, Boulder, Bozeman, MT
(2) University of Colorado, Boulder, Boulder, CO
(3) University of Colorado, Boulder, CO
ABSTRACT: Stratigraphy and Reservoir Geology of Morrow Sandstones, Eastern Colorado and Western Kansas - A 150 Mile Transect Down a Single Incised Valley-Fill System
The Morrow Formation of eastern Colorado and western Kansas is unique in that this system is one of the few in the world where extensive subsurface wireline well control and core data exist in a transect through the entire range of lowstand depositional systems from updip fluvial dominated incised valley-fill systems to deep-water basin-floor systems within a single composite depositional sequence. This poster presents a cross-section through one trunk incised valley-fill drainage with continuous control for 150 miles (240 km) down depositional dip. Along this traverse, internal valley-fill strata change significantly as a function of the interplay of varying depositional systems down gradient in the valley. Key contrasts in reservoir performance are documented as a function of changes in reservoir characteristics, trap controls and trap configurations from updip to downdip within this valley.
The strata of the Morrow Formation were deposited during an icehouse phase of the earth's history in a cratonic basin. High-frequency changes of sea level across an extremely low-gradient depositional surface controlled erosion and deposition. The resultant valley-fill systems have many characteristics in common with published valley-fill models but have significant differences as well. This poster will 1) document the sequence stratigraphic framework of the Morrow Formation in eastern Colorado and western Kansas, 2) demonstrate down-depositional-dip changes in reservoir characteristics and trapping styles within a single valley-fill system along 150 miles (240 km) of its course, and 3) develop a variation of the valley-fill model applicable to strata deposited as a result of glacio-eustacy in cratonic basins.
AAPG Search and Discovery Article #90906©2001 AAPG Annual Convention, Denver, Colorado