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Ouro Preto do Oeste, Brazil

Soriano A.U.,Petrobras | Martins L.F.,Petrobras | Santos de Assumpcao Ventura E.,Petrobras | Teixeira Gerken de Landa F.H.,Petrobras | And 8 more authors.
International Biodeterioration and Biodegradation

The present work consisted of evaluating and comparing, at bench scale, the biodeterioration processes of diesel oil, soy biodiesel (B100 soy), beef tallow biodiesel (B100 beef tallow) and the resulting blends containing 5% biodiesel and 95% diesel oil (B5), throughout 42 days storage. Fuels were stored with and without the inoculation of a microbial consortium from a water drainage tank, under conditions that simulated service station storage. Oxygen consumption and carbon dioxide production were more pronounced in the presence of microbial inoculum, especially for B100 and B5 beef tallow. Diesel oil instead was the least subject to chemical and/or biological oxidation. A trend of increase in acid number was also observed and for B100 soy and B5 beef tallow the regulatory limits were exceeded. Residues deposition was observed in all inoculated fuels, especially in B5 beef tallow. Communities' differentiation depended on biodiesel feedstock and occurred during storage time. Among all microcosms, 18 microbial genera (8 fungal and 10 bacterial) were identified by DNA sequencing, being 17 of them directly linked to: fuel microbial contamination and/or biodegradation (74%); biofuel production or related enzymes expression (26%); biofilm formation and/or exopolysaccharide production (26%), emulsifying properties (11%) and nitrogen fixation (5%). Finally, despite the biodeterioration events in all the fuels, such phenomenon had small magnitude, even in inoculated samples. © 2014 Elsevier Ltd. Source

Dos Santos Neto E.V.,Petrobras | De Morais E.T.,Petrobras | Ferreira A.A.,Petrobras | Torres C.L.,Fundacao Gorceix
Proceedings of the Annual Offshore Technology Conference

Petroleum exploration in presalt reservoirs is reaching increasingly deeper carbonate reservoirs, more and more distant from coastline. Therefore, optimization of investments for a safe and profitable production is critical. Each possible concern on geological conditions that would govern fluid composition and that can bring impact in development cost of an accumulation must be taken into account. In some petroleum accumulations, within presalt reservoirs, along southeastern offshore Brazilian basins, H2S was found. Although H2S concentrations were significantly lower than most of carbonates worldwide, they are enough to be considered in economical evaluations. Therefore, it is important to identify the process that generated H2S and to constraint the main variables that govern its occurrence for a more precise evaluation of the "H2S risk", take into consideration possible pit falls during well intervention. In this way, H 2S is precipitated on site as a salt (Ag2S) from the gas produced during the long lasting producing tests, shipped to laboratory and the 34S/32S ratio is measured. The corresponding δ34S value is the main tool for identifying H2S origin: if it was formed due to organic (BSR, δ34S < -10 ‰) or inorganic (TSR, δ34S > +10 ‰) sulfate reduction. Results of δ34SCDT obtained in H 2S from presalt reservoirs of the Santos Basin spread between +10 ‰ and +20 ‰ typical of TSR. However, temperatures of the reservoirs are lower than that inferred for development of TSR (T > ≈120°C) suggesting that H2S was generated in deeper intervals with significantly higher temperatures. More accuracy in the interpretation about the origin, and clues on migration pathways and accumulation are obtained integrating geochemical, geological and well data production. This integrated approach gives to the explorationist the best understanding about the "H2S risk" in a specific exploratory target. In this work it will be presented a discussion on the methodology for sampling and measuring δ34S for identification of H2S origin. Copyright 2013, Offshore Technology Conference. Source

Schmidt J.S.,Petrobras | Araujo C.V.,Petrobras | Souza I.V.A.F.,Petrobras | Chagas R.B.A.,Fundacao Gorceix
International Journal of Coal Geology

The evaluation of thermal maturity of Lower Paleozoic sedimentary rocks is somewhat complex, mainly because of the absence of humic vitrinite maceral material. Various sedimentary basins of this age contain a syndepositional vitrinite-like maceral that resembles vitrinite but has a lower reflectance. Samples of shales from outcrops and boreholes from the Ponta Grossa Formation (Middle Devonian or older) in the Paraná Basin were studied for maturation assessment. Hydrous pyrolysis assays were conducted for 27 combinations of time and temperature to compare the reflectances of the vitrinite-like maceral and humic vitrinite in response to increasing temperature and time. This data confirmed that the maturation pathway of the vitrinite-like maceral is lower than that of humic vitrinite. The Spore Coloration Index for the outcrop samples was also evaluated for natural series studies. The combination of the natural and artificial series led to the development of two-stage linear regression equations that estimate the equivalent vitrinite reflectance values from measured vitrinite-like maceral reflectances. To validate the proposed equations, reported measurements of vitrinite-like maceral reflectances from sedimentary basins in China, North America and Europe were selected from the literature for comparison. The validations showed that the values obtained from the proposed equations correlated well with other maturity parameters. © 2015 Elsevier B.V. Source

This study aims the proposition of a biostratigraphic zonation based on calcareous nannofossils assemblages recovered from the Quaternary sediments of the well GL-77. The piston core was drilled on the lower slope in the northern Campos Basin, southeastern Brazil. The nannofossil assemblage is rich, well diversified and preserved, and is recognized as being unicellular algae (coccolithophorids and nannoliths), calcareous dinoflagellates and ascidian spicules. According to the biostratigraphic framework were identified the E?, F and G intervals, of the upper Pleistocene-Holocene age. The F Interval can be divided into two parts based on abundance of small Gephyrocapsa: lower (high frequency) and upper (low frequency). The stratigraphic distribution pattern of the abundance of Gephyrocapsa and Emiliania huxleyi throughout the section showed similar values at the upper part of F Interval as has been reported in previous studies. © 2012 by the Sociedade Brasileira de Paleontologia. Source

Jurelevicius D.,Federal University of Rio de Janeiro | Korenblum E.,Federal University of Rio de Janeiro | Casella R.,Fundacao Gorceix | Vital R.L.,Petrobras | Seldin L.,Federal University of Rio de Janeiro
Journal of Microbiology and Biotechnology

Cyperus rotundus L. is a perennial herb that was found to be dominating an area in northeast Brazil previously contaminated with petroleum. In order to increase our knowledge of microorganism-plant interactions in phytoremediation, the bacterial community present in the rhizosphere and roots of C. rotundus was evaluated by culture-dependent and molecular approaches. PCR-DGGE analysis based on the 16S rRNA gene showed that the bacterial community in bulk soil, rhizosphere, and root samples had a high degree of similarity. A complex population of alkane-utilizing bacteria and a variable nitrogen-fixing population were observed via PCR-DGGE analysis of alkB and nifH genes, respectively. In addition, two clone libraries were generated from alkB fragments obtained by PCR of bulk and rhizosphere soil DNA samples. Statistical analyses of these libraries showed that the compositions of their respective populations were different in terms of alkB gene sequences. Using culture-dependent techniques, 209 bacterial strains were isolated from the rhizosphere and rhizoplane/roots of C. rotundus. Dot-blot analysis showed that 17 strains contained both alkB and nifH gene sequences. Partial 16S rRNA gene sequencing revealed that these strains are affiliated with the genera Bosea, Cupriavidus, Enterobacter, Gordonia, Mycoplana, Pandoraea, Pseudomonas, Rhizobium, and Rhodococcus. These isolates can be considered to have great potential for the phytoremediation of soil with C. rotundus in this tropical soil area. © The Korean Society for Microbiology and Biotechnology. Source

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