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Samples were extracted in hexane solvent and diluted in methanol for
analysis. The UVF-3100 analyzer was calibration using
Sitelab's GRO and PAH
calibration kits, CAL-025M and CAL-060M in methanol. The
handheld TD-500D analyzer was calibrated for Heavy PAHs using the
same PAH standards.
DISCRIMINATION BETWEEN FORMATION OIL AND OIL
BASED MUD
"Drilling for oil using an oil based mud (OBM) facilitates the
drilling process but is often confusing for the mudlogging
geologist. Some of the formation oil qualities that are
readily apparent in water based systems are bright fluorescence and
solvent cuts. Both of these attributes are also present when
using OBM whether there is any formation oil present or not.
Often OBM is used where the target is a high gravity oil that
doesn’t stain the cuttings brown from the oil. Steve Greason
of Sitelab Corporation in West Newbury, MA graciously agreed to test
a set of eight samples for OBM vs formation oil. Three
different tests on each of the eight samples were performed using
Sitelab’s UVF-3100D. An additional test using Sitelab’s
TD-500D analyzer was also performed on all eight samples."
"The
test data shows marked elevation of Polyaromatic Hydrocarbons
(PAH’s) in the crude oils plus in the OBM that contained crude oils. Very low values for these same PAH’s were observed in the unused
OBM, pure LVT (mineral oil base of the OBM), and in CFR (a mud
additive that also fluoresces)."
"The equipment shows a clear distinction between
the OBM and formation oil when they are extracted from their liquid
state. Further tests should include testing of the actual cuttings
during realtime drilling."
Lew Sutfin, Horizon Well Logging, Inc.
https://horizon-well-logging.com/
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