Integrated geologic and geophysical mapping: An example from the Muddy Sandstone Wind River basin, Wyoming

Conference · Tue May 01 04:00:00 EDT 1990 · AAPG Bulletin (American Association of Petroleum Geologists); (USA)

OSTI ID:6667899

Johnson, S R ^[1]; Western, S K ^[2]

---

1. BP Exploration, Anchorage, AK (USA)
2. BP Exploratin, Houston, TX (USA)

Muddy Sandstone stratigraphic traps have been the primary stratigraphic exploration target in the Wind River basin (WRB) for BP Exploration and many in industry since the discovery of the Grieve field (30 MMBO, 60 bcf of gas) in 1954. Since 1984 in the eastern WRB, 18 wildcats have been drilled resulting in three new field discoveries which total approximately 23 MMBOE. BP Exploration staff has successfully predicted the reservoir outcome of over 95% of the wildcats by incorporating log facies and facies models with seismic amplitude mapping of the Muddy reflector. The Early Cretaceous Muddy Sandstone unconformably overlies the earlier Cretaceous marine Thermopolis Shale and is conformably overlain by the marine Mowry Shale. An incised valley system was cut into the Thermopolis Shale during a eustatic sea level drop. During the ensuing sea level rise in the southeast portion of the WRB, the Recluse sandstone is the primary Muddy reservoir unit. Secondary Muddy sandstone deposition of marine shoreline sandstones occurred during fluctuations of the primary eustatic sea level cycle. Therefore, in certain areas of the WRB , the Recluse member sandstones can be overlain and/or underlain by marine sandstones. In areas where the older and younger marine sandstones are absent, seismic amplitude mapping, incorporating well control, provides a method of mapping the extent of the valley fill sediments. The Muddy valley-fill sediments are generally less than 30 m thick and are encased in slower velocity shales. When valley-fill sediments are present, the Muddy reflector is high amplitude in contrast to low amplitudes when the valley-fill is absent. Estimates of valley fill lithology are provided through synthetic modeling of well logs representing different lithofacies. The resulting wavelet characterization, which includes wavelet shape and peak-to-trough time separation, improves predictability of sandstone distribution.

• OSTI ID: 6667899
• Report Number(s): CONF-900605--
• Conference Information: Journal Name: AAPG Bulletin (American Association of Petroleum Geologists); (USA) Journal Volume: 74:5
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020200* -- Petroleum-- Reserves
Geology
& Exploration
58 GEOSCIENCES
580000 -- Geosciences
CRETACEOUS PERIOD
DEPOSITION
EXPLORATION
FEDERAL REGION VIII
GEOLOGIC AGES
GEOLOGIC DEPOSITS
GEOLOGIC FORMATIONS
MAPPING
MESOZOIC ERA
MINERAL RESOURCES
NATURAL GAS DEPOSITS
NORTH AMERICA
PETROLEUM DEPOSITS
RESOURCES
ROCKS
SANDSTONES
SEDIMENTARY ROCKS
SHALES
USA
WELL LOGGING
WYOMING