25th International Meeting on Organic Geochemistry IMOG 2011

P-299
Drilling conditions making wells unsuitable for fluid inclusion
studies
Sverre Ekrene Ohm, Helen Haneferd
ConocoPhillips, Tananger, Norway (corresponding author:sverre.e.ohm@conocophillips.com)
A fluid inclusion study carried out on a well in the
Northern North Sea showed a remarkable correlation
between fluid inclusion stratigraphy responses and
depths of bit changes. Further investigation of the well
data suggested that extreme temperatures
occasionally had been generated at the bit-sediment
interface during drilling. Cracking of larger molecules
to an abundance of smaller ones and trapping of
these in inclusions formed by super-cooling of partly
melted sediment explain the correlation. Not all wells
are consequently suitable for fluid inclusion screening
analyses. Thus, before initiating fluid inclusion
studies, wells which have experienced intense heat
during drilling should be identified and avoided.
Figure
To the left various Fluid Inclusion Stratigraphy (FIS)
responses are shown through the well. The right part
of the figure shows a blow-up of that part of the well
which shows the most significant FIS responses. The
gamma ray (GR) and sonic velocity (DT) logs are also
displayed for this depth interval. The numbers 1 – 14
represent bit changes at associated depths and the
colour bar reflects the FIS interpretations. A close
correlation is noted between FIS responses and some
of the bit changes
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