Geochemical and isotopic characterization of oils from Brazilian basins

In organic geochemistry, the determination of the origin of oil can often be accessed by studying its fossil organic molecules. These molecules, the biomarkers, allow us to infer environmental conditions of the source rock, providing the correlation between generated oil and its rock. Despite the wide applicability of biomarkers, molecular geochemical methods do not always allow to effectively differentiate oils generated from source rocks deposited under similar conditions. However, isotopic analysis of individual compounds in oils can help to differentiate sources by establishing more exact fingerprints of the oils. To test the δ13C proxy on individual compounds in biogeochemical analysis, this study presents an integrated assessment of biomarkers, total oil isotopic analysis and individual compounds in oils from five Brazilian basins: Recôncavo Basin, Paraná Basin, Santos Basin, Solimões Basin, and Sergipe-Alagoas Basin. The isotopic and geochemical data reported here reinforces the actual interpretation proposed for the paleoenvironments associated with the source rocks and correlated oils. Analyses of the individual compounds pristane and phytane, compounds that are commonly used as a paleoredox tool, revealed that these individual compounds differ in isotopic values. This result demonstrates that, in most cases, these components have different sources that make difficult the single application of the P/F ratio as a paleoredox tool. Additionally, oils associated with source rocks deposited under similar condition have distinct isotopic values for both whole oil composition and individual compounds. This result highlights that the technique is promising for providing oil fingerprints that can be further useful for the identification of the origin of oil, provided these are pollutants in environmental disasters.Na geoquímica orgânica, a definição da origem do petróleo muitas vezes pode ser acessada por meio do estudo de suas moléculas orgânicas fósseis. Tais moléculas, os biomarcadores, permitem inferir condições ambientais da rocha geradora, possibilitando a correlação entre óleo gerado e sua rocha. Apesar da ampla aplicabilidade dos biomarcadores, métodos geoquímicos moleculares nem sempre permitem diferenciar com efetividade óleos gerados em condições paleoambientais similares. Contudo, a análise isotópica de compostos individuais em óleos pode auxiliar na diferenciação de fontes estabelecendo identidades mais exatas dos óleos. Com o objetivo de testar a ferramenta δ13C em compostos individuais na análise biogeoquímica, o presente estudo apresenta a avaliação integrada de biomarcadores, análise isotópica de óleo total e de compostos individuais em óleos oriundos de cinco bacias brasileiras: Bacia do Recôncavo, Bacia do Paraná, Bacia de Santos, Bacia do Solimões e Bacia de Sergipe-Alagoas. Os dados isotópicos e geoquímicos obtidos corroboram a interpretação atual proposta para seus ambientes geradores. As análises dos compostos individuais pristano e fitano, cuja razão é amplamente utilizada como uma ferramenta de paleoredox, mostrou que esses compostos apresentaram valores isotópicos diferenciados. Tal resultado demonstra que, na maioria dos casos, esses compostos tiveram fontes distintas, o que impõe certa cautela na aplicabilidade da razão P/F como uma ferramenta paleoredox. Adicionalmente, óleos associados a rochas geradoras com ambientes deposicionais semelhantes apresentaram valores isotópicos distintos tanto para composição total quanto para compostos individuais. Tal resultado sugere que a técnica é promissora na definição de identidades de óleos que podem ser utilizadas em estudos de correlação e identificação da origem de petróleo, quando esses são poluentes em desastres ambientais

Requirements for Bend Insensitive Fiber in Millimeter-Wave Fronthaul Systems

The impact of fiber bending on mm-wave radio-over-fiber transmission is investigated and the need for bend insensitive fiber for front-haul installation confirmed. A 70m W-band hybrid photonic-wireless link including bend insensitive fiber is demonstrated with BER<10\u3csup\u3e-6\u3c/sup\u3e at 5mm bending radius

W-band photonic-wireless link with a Schottky diode envelope detector and bend insensitive fiber

The performance and potential of a W-band radio-over-fiber link is analyzed, including a characterization of the wireless channel. The presented setup focuses on minimizing complexity in the radio frequency domain, using a passive radio frequency transmitter and a Schottky diode based envelope detector. Performance is experimentally validated with carriers at 75–87GHz over wireless distances of 30–70m. Finally the necessity for and impact of bend insensitive fiber for on-site installation are discussed and experimentally investigated

Performance Evaluation of Wavelet-Coded OFDM on a 4.9 Gbps W-Band Radio-over-Fiber Link

Future generation mobile communications running on mm-wave frequencies will require great robustness against frequency selective channels. In this paper, we evaluate the transmission performance of 4.9 Gb/s wavelet-coded orthogonal frequency division multiplexing (OFDM) signals on a 10 km fiber plus 58 m wireless radio-over-fiber link using a mm-wave radio frequency carrier. The results show that a 2 × 128 wavelet-coded OFDM system achieves a bit-error rate of 1e-4 with nearly 2.5 dB less signal-to-noise ratio than a convolutional coded OFDM system with equivalent spectral efficiency for 8 GHz-wide signals with 512 subcarriers on a carrier frequency of 86 GHz. Our findings confirm the Tzannes’ theory that wavelet coding enables high diversity gains with a low complexity receiver and, most notably, without compromising the system’s spectral efficiency