During the past two years, Minerals Management Service, U. S. Department of the Interior, has classified the reservoir sands from the approximately 1,100 fields across the entire northern Gulf of Mexico into groups of genetically related plays defined by production, chronostratigraphy, lithostratigraphy, and structure. Sands within each of the 12 chronozones from lower Miocene to upper Pleistocene were classified as transgressive, aggradational, progradational, or deep-sea fan facies. Proved reserves plays, hydrocarbon extents, and facies sand limits were mapped for each chronozone.

Dramatic changes in depositional styles from the Miocene through the Pliocene are observed in the north-central Gulf of Mexico as the ancestral Mississippi River delta moved both basinward and eastward across offshore Louisiana. The depocenter shifted back to the west and significantly basinward during the Pleistocene. Useful hydrocarbon exploration and development tools developed as a result of this study will be presented.

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