Intraslope basin reservoirs deposited by gravity-driven processes: Ship Shoal and Ewing Banks areas, offshore Louisiana

Journal Article · Sun Sep 01 04:00:00 EDT 1996 · AAPG Bulletin

DOI:https://doi.org/10.5724/gcs.96.17.0007· OSTI ID:411877

Armentrout, J M; Malecek, S J; Mathur, V R; Neuder, G L; Ragan, G M ^[1]

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1. Mobile Oil Corp., Dallas, TX (United States)

Seismic facies and high-resolution biostratigraphic analysis provide a sequence stratigraphic framework for interpreting lateral distribution of sand-prone facies and reservoir connectivity in the Ship Shoal 351-358 to Ewing Bank 988 area, offshore Louisiana. The interval of interest is an isochron thick interpreted as a lowstand systems tract deposited at bathyal water depths within an intraslope-basin. This basin is approximately 50 kilometers from the age equivalent shelf/slope break. The isochron thick was deposited between the late Pliocene Discoaster Pentaradiatus and early Pleistocene Discoaster brouweri Condensed Sections. The D. pentaradiatus-D. brouweri sequence consists of the synclinal fill of a salt withdrawal basin forming an isochron thick that thins onto adjacent salt-cored structural highs. This isochron interval was subdivided into four seismic facies and each was calibrated with local well data. Mapped patterns of these seismic facies suggest a network of channel systems within a slope valley supplying sand by gravity-driven processes into a local salt withdrawal intrastope-basin. Following the above analysis, three wells (351No.2, 359No.1, 988No.3) and two side-tracks (351No.2stNo.l and stNo.2) were drilled to further test the prospectivity of the area. Rock type and hydrocarbon predictions based on seismic facies analysis were confirmed by the wells. Sandstones occur within the axes of isochron thicks and shales dominate the isochron thins over paleo-highs with gradational facies between. Hydrocarbon accumulation occurs in two settings: (1) channel-fed lobes with blocky log character yield hydrocarbons within areas of structural closure; and (2) overbank facies which contain hydrocarbons in low resistivity pay both within and outside of structural closure. Local abundance peaks of planktonic microfossils provide correlation control between the four depositional lobes of this lowstand deposit.

• Sponsoring Organization: USDOE
• OSTI ID: 411877
• Report Number(s): CONF-9610180--
• Journal Information: AAPG Bulletin, Journal Name: AAPG Bulletin Journal Issue: 9 Vol. 80; ISSN 0149-1423; ISSN AABUD2
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
EXPLORATION
LOUISIANA
OFFSHORE SITES
PETROLEUM
SEDIMENTARY BASINS
SEISMIC SURVEYS
STRATIGRAPHY