MINNELUSA FORMATION POWDER RIVER BASIN
SEA, SAND AND OIL
MINNELUSA CONSORTIUM
Jackson, Wyoming
February 4, 2009
February 4, 2009 Gene R. George PG No. 8
MINNELUSA FORMATION
• INTRODUCTION• PALEOGEOGRAPHY• DEPOSITIONAL HISTORY• MINNELUSA PRODUCTION
February 4, 2009 Gene R. George PG No. 8
INTRODUCTION
• Minnelusa
means Rapid Water in Sioux• Named by N. H. Winchell 1895 on the Rapid River
near Rapid City S. D.• Permian in age, Wolfcampian• Deposition similar to Sabkha
in Persian Gulf
• Al Allen identified the Eolian
Character in 1966• 129 Fields produced more than 1 MM BO• Raven Creek is the largest field at 47 MM BO• Deposition and Diagenesis
affects production
February 4, 2009 Gene R. George PG No. 8
PALEOGEOGRPHY
• Pangaea was oriented so that Wyoming was near 15 degrees north Latitude.
• Trade winds blew across low‐lying areas near shallow seas
• Persian Gulf is the Modern Analogy
• Compare Persian Gulf to PRB
February 4, 2009 Gene R. George PG No. 8
Stampfli & Borel 2000
PANGAEA
Wyoming
Trade Winds
Equator
Wyoming
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SABKHA
SIOUXIA
George, WGA 1984
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Persian Gulf
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QATA R
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Next View
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Shamalwinds
Next View
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TIDAL DELTA
LONGSHORE SPIT
MARINE SAND
WATER
CARBONATE
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DUNES = 30’
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Shamal
Winds
Shinn, 1973
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Comparison: Persian Gulf to PRB
6 miles6 miles WIND
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DEPOSITIONAL HISTORY
• Dune types related to sand supply and wind direction
• Internal structure caused by episodic events and wetting
• Marine provides early cement and stabilization
• Cyclic sequences provide traps• Tectonic movements yield meteoric waters for
cement removal and hydrocarbon emplacement
• Now we know‐
where do we drill?
February 4, 2009 Gene R. George PG No. 8
Schenk SEPM 1990
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LINE OF SECTION
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Shinn 1973
CORE
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Fryberger 1973Fryberger 1990
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Fryberger 1990WET
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Schenk 1990
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MINNELUSA STRATIGRAPHY
• Trap Types– Opeche
truncation and sealing
– Loss of porosity by anhydrite cementation (also change from dune to interdune
or sheetsand)
– Encasement by dolomite
• Recognizing depositional environments– Comparing cores to logs– Correlation by dolomites and depositional
environments
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Fryberger 1984
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Fryberger 1984
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Fryberger 1984
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Fryberger 1984
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Fryberger 1984
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HAWK POINT JAMES
James 1998
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MINNELUSA FIELDS
• Raven Creek No. 1 At 47 MMBO
• Correlation key = B Dolomite– Look for sequences– Look for offsetting relationships– Find the B Dolomite (hint always drill deep
enough to see the C sand). Many wells only go to the B sand and could be leaving a C sand field
behind.
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George WGA 1984
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B Sand Porosity
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Upper C Sand Porosity
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Lower C Sand Porosity
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B Sands
Lower C Sand
Upper C Sand Tite
Upper C Sand
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CONCLUSIONS
• PERSIAN GULF ANALYOGY IS PROVEN• B DOLOMITE AND OFFSETTING SANDS KEYS
TO CORRELATION
• DUNE PRESERVATION AND DIAGENESIS CAN CREATE COMPARTMENTS BY FACIES CHANGE OR CEMENTATION
• POROSITY ZONE CORRELATION IS KEY TO EFFECTIVE FLOOD SWEEP
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