ABSTRACT: Sequence Stratigraphy and Stratigraphic Modeling for Improved Understanding of Mid-Continent Paleozoic Reservoirs
WATNEY, W. LYNN, J. A. FRENCH, J. C. WONG, H. R. FELDMAN, E. K. FRANSEEN, and W. J. GUY, Kansas Geological Survey, Lawrence, KS
Stratigraphic studies of all types of mid-continent Paleozoic petroleum reservoirs often result in similar conclusions-that sandstones and carbonate units are interrupted by numerous surfaces representing extended periods of nondeposition or erosion. These temporally and spatially distinct packages of strata, which are termed genetic units, are equivalent to 4th- and 5th-order sedimentary cycles (also known as depositional sequences and parasequences).
The genetic units and bounding surfaces provide a framework of fluid flow units in a reservoir due to facies offsets across the bounding surfaces and common juxtaposition of porous and nonporous lithologies. Thus, the recognition and interpretation of genetic units improves our ability to define and predict reservoir heterogeneity.
Elements of genetic units were recognized in the mid-continent in cyclothems over 60 years ago by workers such as Wanless, Weller, and R.C. Moore, and their geometries were mapped in the subsurface and used to infer base-level (relative sea level) changes over 30 years ago (Van Siclen). The refined concepts of today's sequence stratigraphy, better methods of subsurface data collection, and advances in computing such as three-dimensional visualization and stratigraphic simulation are moving geology further into the quantitative realm. These approaches are fundamentally built upon the recognition of these genetic units.
A diverse set of examples using these concepts and techniques illustrates the ability to enhance the understanding of reservoir heterogeneity. Examples are from the Lower Ordovician Simpson Group, the Upper Devonian Misener sandstone and limestone, and the Upper Pennsylvanian Kansas City Group in Kansas.
AAPG Search and Discovery Article #91013©1992 AAPG Eastern Section Meeting, Champaign, Illinois, September 20-22, 1992 (2009)