Biodegradation of Hydrocarbons in the Potiguar
Dreyfus, S.1, C. Pecheyran1, C.P. Lienemann2, C. Magnier3, L.A.F Trindade4, A. Prinzhofer5, O.F.X. Donard1 (1) LCABIE / CNRS UMR 5034, Pau, France (2) Institut Francais du Petrole, Vernaison, France (3) Geology-Geochemistry, Institut Francais du Petrole (4) CENPES, Petrobras, Brazil (5) Institut Francais du Petrole, Rueil-Malmaison Cedex, France
In the recent
years, intensive studies have been dedicated to the geochemical characterization
of petroleum systems. Trace and ultra trace metals in crude oils may be used as
geochemical markers in oil-oil and oil-source rock correlations,
identification of source rocks depositional environment and in the
quantification of oils thermal maturity and biodegradation levels.
Elemental signatures such as Ni and V concentrations evolution in crude oils
have already been used to determine the degree of reservoir biodegradation.
However new parameters are needed to improve the general knowledge about
migration, maturation, mixing and biodegradation of the oil from an
inorganic or bioinorganic angle. Sensitive methods are then required to
analyze other elements occurring in petroleum in very low concentration
(like Mo, Pb, Cu, Cd, Sn, Ba,…).
The instrumental limitations of the most common techniques used so far (AAS,
ICP-OES), have been the main reason for the poor knowledge about inorganic
constituents of crude oil. Performances of the inductively plasma mass
spectrometry allows now the detection of very low concentrations in an organic
matrix. A method was developed to analyze directly trace and ultra-trace metal
elements in crude oil and its fractions (maltenes, asphaltenes) by ICP-MS after sample dilution in xylene. Several biodegraded and non biodegraded crude oils
and fractions originating from the