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Sedimentology |
1 Koninklijke Shell Exploratie en Produktie Laboratorium, Volmerlaan 6, 2288 GD Rijswijk ZH, Netherlands
2 Shell UK Expro, Shell Mex House, Strand, London WC2R ODX, UK
The ability of SHDT processing techniques to produce detailed sedimentological information has been evaluated by comparing the data with 3000 ft of cores covering shallow marine, deltaic, lacustrine, fluvial and aeolian sedimentary environments. It has been shown previously that, by using side-by-side processing, realistic sedimentary dip sequences through sedimentary bodies can be obtained from SHDT data under normal conditions. However, optimum results require processing parameters to be chosen compatible with the scale of the sedimentary structures present. Furthermore, post-processing selection procedures are required to remove noise and to identify dips representing foreset inclination which can be interpreted in terms of flow direction and sand body orientation.
The sedimentological interpretation of downhole dips is often difficult. It may be improved by comparison with vertical dip sequences from outcrops. Sedimentary dip profiles have been measured as part of field work carried out in the Pocahontas Basin of Kentucky. Extensive roadcuts not only enable an unambiguous sedimentological interpretation, but also exhibit numerous relict blast-boreholes, in which vertical dip profiles can be measured under conditions similar to downhole logging. The data now available show that even contradictory dip sequences may be a proper representation of the reality. Systematic collection of sedimentary dip sequences will provide guidelines for a realistic interpretation of downhole records of sedimentary dips.
