Computer modeling of Minnelusa (Pennsylvanian-Permian) paleotopography in eastern Powder River basin, Wyoming, with a case history
Most Minnelusa Formation (Pennsylvanian-Permian) oil production in the Powder River basin is from paleotopographic traps. These traps occur where upper Minnelusa dune sands are encased in the overlying supratidal red Opeche Shale (Permian). The morphology of these sands suggests northwest-southeast-trending barchanoid sand ridges. Thickness variations in the Opeche mirror the relief on the Minnelusa surface. Opeche isopachous maps are one of the main methods used to explore for Minnelusa paleotopographic traps. Hand-contoured isopachous maps can be subject to ambiguous interpretations in areas of low-density control. This difficulty is partially overcome when the map is mathematically produced. Observations from oil tests in the area indicate that Minnelusa paleotopography is cyclic with a wavelength of approximately 3 mi (5 km). Double Fourier transforms are appropriate in modeling this kind of cyclic data. For a test township, the calculated double Fourier surfaces showed good correlation with the actual data values. This technique was then applied to a Minnelusa prospect in Campbell County, Wyoming. Double Fourier surfaces were calculated for several structural datums and isopach intervals. Additionally, regional dip was determined from a polynomial fit, the section was restored to horizontal, and then was modeled to reveal paleotopography. The paleotopographic-high axes and Opeche thin axes showed remarkable coincidence. This trend is believed to represent the trace of a paleo sand dune. A test well sited using conventional geologic methods plus input from the double Fourier maps confirmed the accuracy of the calculated surface.
- Research Organization:
- Blue Sky Oil and Gas, Denver, CO
- OSTI ID:
- 6387144
- Report Number(s):
- CONF-8405216-
- Journal Information:
- Am. Assoc. Pet. Geol., Bull.; (United States), Journal Name: Am. Assoc. Pet. Geol., Bull.; (United States) Vol. 68:4; ISSN AAPGB
- Country of Publication:
- United States
- Language:
- English
Similar Records
Use of seismic stratigraphy for Minnelusa exploration, northeastern Wyoming
Tensleep, Minnelusa, and Casper Formations, Wyoming and adjacent states: study of Permian-Pennsylvanian oil occurrence and oil gravity distribution
Related Subjects
020200* -- Petroleum-- Reserves
Geology
& Exploration
COMPUTER CALCULATIONS
FEDERAL REGION VIII
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC FORMATIONS
GEOLOGIC STRUCTURES
GEOLOGIC TRAPS
MAPPING
MATHEMATICAL MODELS
MINERAL RESOURCES
NORTH AMERICA
PALEOZOIC ERA
PENNSYLVANIAN PERIOD
PERMIAN PERIOD
PETROLEUM DEPOSITS
RESOURCES
ROCKS
SANDSTONES
SEDIMENTARY BASINS
SEDIMENTARY ROCKS
SHALES
USA
WYOMING