--> Abstract: Platform-Scale Facies Distributions Using LANDSAT Data from Isolated Carbonate Platforms: Methods to Constrain Lateral Facies Continuity for Geologic Modeling, by Steven L. Bachtel and Robert L. Brovey; #90039 (2005)

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Platform-Scale Facies Distributions Using LANDSAT Data from Isolated Carbonate Platforms: Methods to Constrain Lateral Facies Continuity for Geologic Modeling

Steven L. Bachtel and Robert L. Brovey
ExxonMobil Upstream Research, Houston, TX

Subsurface geologic models are typically better constrained vertically (well data) than laterally (interwell correlations, seismic, outcrop, or conceptual models). Understanding lateral continuity of carbonate facies can be improved by a more quantitative approach to studying lateral facies distributions in modern environments.

Automated techniques to predict bathymetry and facies from LANDSAT data were applied to a series of modern platforms to understand facies to water depth relationships and to define lateral continuity changes with respect to hydrography and platform geometry. Unsupervised classification techniques were used in image processing software to predict bathymetry using the average brightness of the visible color bands (adjusted for shallow, dark-colored organic boundstone and vegetation). The three visible color bands, convolved with average brightness, were then classified to predict facies. Histograms of water depth versus facies can be constructed from the predicted bathymetry and facies grids. A program was also developed to capture facies lengths that can then be related to modern wind data and the geometry of the platform.

Variations in reef crest and back-reef sand apron widths were measured manually and evaluated in context with wind direction and coastline morphology. Cross correlation of the facies widths indicates a negative correlation between reef crest width and sand apron width (i.e. - wider reef crests typically have narrower sand aprons). At high-angles of incidence, this relationship is more pronounced due to wider reef crests. At low-angle of incidence, reef crest widths have a higher range, especially for those reef crests with narrow sand aprons.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005