Do High Resolution Sequence Stratigraphic Studies of Quaternary Strata Yield Useful Results for Oil and Gas Exploration?
ANDERSON, JOHN B., LAURA A. BANFIELD, PHILIP J. BART, BRENDA J. ECKLES, ANTONIO B. RODRIGUEZ, JENNIFER N. SNOW
A long term study of the northern Gulf of Mexico continental shelf and upper
slope focuses on examining the response of different depositional systems
(fluvial, deltaic
, coastal, etc.) to rising and falling sea level during the
last few glacial eustatic cycles. The data base consists of over 20,000
kilometers of high resolution seismic data and several hundred oil company
platform borings and cores. The study area extends from the west Florida shelf
to the Rio Grande and includes very different fluvial input, shelf gradient, and
climatic and oceanographic shelf settings.
A series of strike and dip-oriented cross sections and paleogeographic maps
extending across the study area and coinciding with prominent seismic
stratigraphic surfaces illustrate how deposition varied from one area to the
next at specific times and sea-level positions. These surfaces include the
maximum flooding surface of the last highstand, the sequence boundary associated
with the subsequent lowstand and the following transgressive ravinement surface.
Variations between deposits are profound. In some areas the stratigraphic
section is dominated by highstand deposits while other areas are dominated by
transgressive and/or lowstand deposits. Potential time equivalent reservoirs
also vary along the shelf. For example, highstand sand bodies are dominantly
deltaic
deposits on the south Texas and west Florida shelves and barrier/bar
sands on the central Texas shelf. Reasonable repetition of depositional systems
occurs within any given area over several glacial eustatic cycles. Therefore,
predictable trends are observed in terms of reservoir character, shape, and
stratigraphic position.