Geochemical Comparison of Oils and Source Rocks from Barents Sea

The main objective of this study is to attempt to correlate twelve (12) core and (1) one outcrop source rock samples, recovered from the Hammerfest Basin, the Nyslepp/Måsøy Fault Complex, the Finnmark Platform, the Nordkapp Basin, the Svalis Dome, the Bjarmeland Platform and the outcrop sample from the Trehøgdene on Svalbard, with ten (10) oil samples from the Hammerfest Basin, the Nyslepp/Måsøy Fault Complex, the Bjarmeland Platform, the Loppa High and the Nordkapp Basin in western Barents Sea, for the purpose of understanding better the source and maturity aspects of the petroleums. The aim of this study is to attempt to correlate source rocks with migrated oils in order to better understand the source rock to oil relationships in the region; hence 11 Mesozoic (e.g Kapp Toscana-Adventalen-Sassendalen Groups) organic rich shales and siltstones, as well as 1 from Upper Paleozoic (Tempelfjorden Group) are attempted to be correlated with 9 Mesozoic oil samples (e.g Kapp Toscana-Sassendalen Groups) and 1 oil sample from the Upper Paleozoic (Gipsdalen Group), all being extracted from wells operated in western Barents Sea. There is also an outcrop sample, namely SO-21, from the De Geerdalen Formation from onshore Svalbard that was analyzed due to its special, almost standard type, chromatogram. In both cases the samples were annotated and calibrated based on the standard sample NSO-1 (North Sea Oil) from Oseberg field, one of the most widespread world-wide used standards, introduced by the Norwegian petroleum industry and NPD. Therefore, gas chromatography coupled with mass spectrometry (GC-MS) technique was applied to get the m/z (mass to ion ratios), namely 191, 217, 218, 231, 253, 178, 198 and 192 in order to obtain information about a series of biomarkers and associated parameters. The gas chromatography coupled with flame ionization detector (GC-FID) technique was used to obtain chromatograms, mainly from C15 to C40 in order to calculate the ratios of the isoprenoids, pristane and phytane (Pr/Ph) and isoprenoids with n-alkanes, Pr/n-C17 and Ph/n-C18. The CPI (carbon preference index) was computed for both datasets and the OEP (odd to even predominance) for the oil dataset. Geochemical correlation was used to evaluate if there is any genetic relationship between the source rocks and the oils. The results obtained from the gas chromatography analyses were used to make conventional plots according to previous studies and to obtain information about the depositional environment, the biodegradation, the maturity and the type of kerogen. These methodologies were used to evaluate the potential source for the migrated oil. Some of the oil samples are medium biodegraded, meaning the composition of the organic matter is affected by microbial alteration, thus there was an attempt to use as many parameters as possible, in order to reach safe conclusions, following also an evaluation of the levels of biodegradation