Seismic stratigraphy, sedimentology, and reservoir potential of a late pleistocene shelf-edge delta

Conference · Wed Sep 01 04:00:00 EDT 1993 · AAPG Bulletin (American Association of Petroleum Geologists); (United States)

OSTI ID:6915719

Roberts, H H ^[1]; Sydow, J; Bouma, A H ^[2]

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1. Coastal Studies Institute, Baton Rouge, LA (United States)
2. Louisiana State Univ., Baton Rouge, LA (United States)

Evaluation of a 92-m continuous boring through a shelf-edge delta sequence in Main Pass lease area, Block 303 (MP303), and 4500 line-km of high-resolution seismic profiles on the outer Mississippi-Alabama shelf have led to a better understanding of the internal architecture of fluvio-deltaic systems during falling to low sea level periods. The resulting stratigraphic mapping supplies valuable knowledge about the lithologic character, stratigraphic position, distribution, and compartmentalization of reservoir facies in an outer shelf setting. The clinoforms of the landward-thinning delta wedge have prograded onto a shelf-wide, high-amplitude reflector. The deltaic clinoform wedge appears to be sand rich. Steep clinoforms at the boring site correspond to the top half of the deltaic sequence, consisting of silty to clean, upper delta front fine sands. Mapping of steep clinoforms indicate that delta sands are volumetrically the most significant reservoir facies on the outer shelf. The broad evacuation created by fluvial scour is a northeast to southwest trending feature, which is filled with mainly medium to coarse sands and gravel, and minor estuarine sand silts at the boring site. The clean fluvial sands form the best quality reservoir facies. Delta reservoir facies have been removed where overridden by widespread fluvial scour on the middle shelf. Fluvial reworking during sea level lowering thus results in poor preservation potential of preceding highstand-delta deposits on the middle and inner shelf. This reworking provides remobilized sand-rich sediment for shelf-edge delta construction. The fluvial deposits in the boring are capped by the bayline flooding surface, which is in turn overlain by estuarine deposits, the transgressive ravinement surface, and finally, submarine shoal and thin sheet deposits. Submarine shoals are sandy, but contain abundant shell material. Shoals are of the poorest quality and volumetrically least important reservoir facies.

• OSTI ID: 6915719
• Report Number(s): CONF-9310237--
• Conference Information: Journal Name: AAPG Bulletin (American Association of Petroleum Geologists); (United States) Journal Volume: 77:9
• Country of Publication: United States
• Language: English

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CONTINENTAL MARGIN
CONTINENTAL SHELF
DEVELOPED COUNTRIES
DISTRIBUTION
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QUATERNARY PERIOD
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