Produção Nacional
Distribuição e composição geoquímica de inclusões fluidas de petróleo comparadas com as do óleo cru, indícios e extratos em um poço submarino na Bacia de Campos, Brasil
2008; Sociedade Brasileira de Geologia; Volume: 38; Issue: 1 Linguagem: Inglês
ISSN
2177-4382
AutoresCarlos Eduardo Silva Coelho, Simon C. George, Herbert Volk, Peter J. Eadington, Andrew Ross,
Tópico(s)Geological formations and processes
ResumoAn offshore well containing a shallow, biodegraded producible oil zone underlain by an intermediate oil show zone (slightly biodegraded) and a deep oil show (unbiodegraded). The objective of this study was to screen for the presence of oil-bearing fluid inclusions (FIs), use this information for determining the extent of paleo-oil zones and compare their geochemistry to oils, oil shows and rock extracts. A Grains with Oil Inclusions (GOI TM) value of 5.3% in the producible oil zone is moderate but FIs are small (< 5 μm) and rare. Lower GOI values (0.7-2.0%) in the intermediate oil show interval are evidence for migration and possibly accumulation of oil. In the deep oil show FIs occur more frequently (GOI = 9.6-19%), are larger and are more abundant within grains. Their geochemical signature is similar to the oil show in terms of secondary alteration (non-biodegraded), maturity (peak of oil window) and source signature (clay-rich, probably Cretaceous or younger, suboxic marine shales). The inclusion oil does not correlate with the less mature and lacustrine producible oil or the intermediate oil show, nor does it correlates with the significantly less mature marine mudstones in the well. Similar maturities (peak of oil window) are indicated by parameters calculated from a wide boiling range of compounds, so PIs probably trapped oil from a single charge event. Both palaeo- and current oil in the deep oil show interval differ from the upper producible oil and we infer that they were generated from a deeper source and migrated vertically.
Referência(s)