Abstract: Distinction Between Deltaic and "Deep Water" Sands, Gulf Coast Province, Based on Analysis of Small Samples

By

David K. Davies

The Tertiary to recent geologic record of the Gulf Coastal Province includes significant amounts of sand deposited in deltaic and "deep water" environments. Interpretation of the correct environment of deposition of any deltaic or deep-water sand is of significance because depositional environment controls the trend, shape, and, at times, the dimensions and quality of sand reservoirs. Interpretation of depositional environment is best undertaken using conventional cores. In the Gulf Coastal Province, conventional cores are taken infrequently, whereas sidewall cores and cuttings samples are much more abundant. These small samples can be used for environmental interpretations at a sophisticated level.

Petrographic analysis of thin sections prepared from a wide range of Gulf Coast sidewall cores and cuttings samples demonstrates that quantifiable changes in composition and texture can be used to differentiate between deltaic and "deep water" sands. These data can be particularly informative when used in conjunction with gamma ray, S.P., and resistivity curves from geophysical logs.

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