Perception vs. reality in deep-water exploration
- Mobil Exploration & Producing Technical Center, Dallas, TX (United States)
The common perception in exploration is that deep-water sands are predominantly a product of low- and high-density turbidity currents, and that submarine-fan models with channel/levee and lobe elements are the norm. The reality, however, is that deep-water systems are extremely complex and variable in terms of depositional processes and sand-body geometries. For example, the Bourna Sequence, composed of T{sub a}, T{sub b}, T{sub c}, T{sub d}, and T{sub e} divisions, is believed to be the product of a turbidity current. However, recent core and outcrop studies show that the complete and partial Bouma sequences also can be explained by processes other than turbidity currents, such as sandy debris flows (i.e., {open_quotes}T{sub a}{close_quotes}) and bottom-current reworking (i.e., {open_quotes}T{sub b}, T{sub c} and T{sub d}{close_quotes}). Massive sands are interpreted routinely as high-density turbidites, but the reality is that the term {open_quotes}high-density turbidity current{close_quotes} commonly refers to sandy debris flow in terms of flow theology and sediment-support mechanism. Deep-water sequences in the North Sea, Norwegian Sea, Offshore Gabon, Offshore Nigeria, Gulf of Mexico, and the Ouachita Mountains are generally considered to be turbidite-rich submarine fans. However, the reality is that these sequences are composed predominantly of sandy slumps and debris flows, not turbidites. Fan models are attractive to explorationists because of their predictable sheet-like geometries; however, these simplistic conceptual models are obsolete because they defy reality. Although the turbidite paradigm is alive and well for now in the minds of many sedimentologists and sequence stratigraphers, the turbidites themselves that form the foundation for fan models are becoming an endangered facies!
- OSTI ID:
- 425861
- Report Number(s):
- CONF-960527-; TRN: 96:004994-0502
- Resource Relation:
- Conference: Annual convention of the American Association of Petroleum Geologists, Inc. and the Society for Sedimentary Geology: global exploration and geotechnology, San Diego, CA (United States), 19-22 May 1996; Other Information: PBD: 1996; Related Information: Is Part Of 1996 AAPG annual convention. Volume 5; PB: 231 p.
- Country of Publication:
- United States
- Language:
- English
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