8.4 Small-Scale Variations in C/O Ratios
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By acquiring the inelastic gamma ray and time of ight spectra, the C and O
concentration ratios could be obtained to determine small-scale variations in
oil saturation and borehole oil fraction. Information on small-scale variations
in lithology, porosity, and salinity can also be obtained. Logging is proposed
to be performed as station measurements in this mode, but for higher porosi-
ties, low speed (≤20 m/h) continuous passes will be tested. A carbon signal can
originate from the borehole, the cement behind the casing, the formation rock,
and the formation uid. In the proposed approach, the fraction of the ratio of
C and O yields being a measure of the amount of oil around the tool will be