Control on reservoir distribution and quality in regressive member of an Upper Pennsylvanian cyclothem

Conference · Mon Aug 01 04:00:00 EDT 1983 · Am. Assoc. Pet. Geol., Bull.; (United States)

OSTI ID:6527159

Prather, B E

Isopach maps and diagenetic features may be used to predict the distribution of reservoir-quality rock in the D-zone cyclothem of the Lansing-Kansas City Groups in southwestern Nebraska. The D-zone cyclothem was deposited during one major oscillation of the epeiric sea in late Pennsylvanian (Missourian). This cyclothem records a transgression of sea level followed by a major regression. During the regressive phase there was a brief sea level transgression. The D-zone cyclothem consists of the four basic lithofacies common to most cyclic deposits of this age in northwestern Kansas and southwestern Nebraska: 1) a thin lower carbonate unit deposited in a shallow-marine environment; 2) a laterally extensive lower shale unit of marine origin resulting from a terrigenous influx from the north; 3) a complex upper carbonate unit deposited in shoaling water during waning terrigenous influx; and 4) an upper shale unit deposited in tidal flat to nonmarine environments. Conclusions: 1) paleobathymetery is reflected in an isopach map of the upper shale unit; 2) distribution of grain-supported rock is controlled in part by formation of bathymetric highs while underlying shales compacted around preexisting topographic highs; 3) enhancement of porosity by dissolution in the grain-supported rocks occurred in the freshwater phreatic and vadose zoes; and 4) recognition of diagenetic features associated with formation of paleowater tables may be used to predict the distribution of porosity in these grainstones.

• Research Organization: Shell Oil Co., New Orleans, LA
• OSTI ID: 6527159
• Report Number(s): CONF-8310309-
• Conference Information: Journal Name: Am. Assoc. Pet. Geol., Bull.; (United States) Journal Volume: 67:8
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200* -- Petroleum-- Reserves
Geology
& Exploration
03 NATURAL GAS
030200 -- Natural Gas-- Reserves
Geology
& Exploration
DIAGENESIS
DISSOLUTION
DISTRIBUTION
FEDERAL REGION VII
GEOLOGIC AGES
GEOLOGY
LITHOLOGY
NEBRASKA
NORTH AMERICA
PALEOZOIC ERA
PENNSYLVANIAN PERIOD
POROSITY
RESERVOIR ROCK
SEDIMENTATION
STRATIGRAPHY
USA