Banca de QUALIFICAÇÃO: Gabriella Talamo Fontaneta

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : Gabriella Talamo Fontaneta
DATE: 28/06/2024
TIME: 14:00
LOCAL: Sala de Videoconferência do IGD
TITLE:

South Atlantic Saline Crisis: understanding the evolution from pre-salt alkaline paleolakes to evaporitic basin, Early Cretaceous, Santos Basin, Brazil.

KEY WORDS:

Eevaporites; Pre-Salt; Marco Lula; travertine; carbon, oxygen and strontium stable isotopes; U/Pb dating.

PAGES: 88
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUMMARY:

The evaporites of the eastern Brazilian margin have always been considered effective seals for petroleum systems, and their other geological characteristics have been under-examined. However, with the advance of Pre-salt oil production in the Santos Basin, the heterogeneity of the evaporite section has gained notorious relevance, evidenced by the geological risks faced during oil and gas drilling processes. Stratigraphically below the salt, it is found the top section of the Barra Velha Formation, known as Marco Lula, which has different petrographic and geochemical characteristics from the the Barra Velha Formation basal sections and whose relationship with the evaporites is not well understood. The aim of this doctoral study is to investigate the genetic relationships between the lacustrine carbonates deposited at the end of the sag phase and the basal anhydrites of the frankly evaporitic deposits of the Ariri Formation in the Santos Basin, in order to understand the origin of the fluids that form these rocks. For this purpose, it was selected five wells that sampled the interesting stratigraphic section and carried out petrographic, carbon, oxygen and strontium stable isotope analyses on bulk rock and punctual strontium analyses, as well as some U/Pb dating. These analyses, until the present moment of the research, allowed the identification of travertines with a negative carbon isotope composition, which suggest the presence of fluids strongly depleted in ¹³C during the precipitation of these rocks, such as methane exudations. Based on the ⁸⁷Sr/⁸⁶Sr isotope ratios, it was possible to identify a marine source contribution in the precipitation of the basal anhydrites, which differ from the carbonates of Marco Lula. The ages obtained by U/Pb dating are older than expected for these rocks, which requires further research into the behavior of this isotopic system in carbonates. In the future stages of this research, it is intended to carry out isotopic microanalyses of carbon, oxygen and sulphur by SIMS and carbon and oxygen clumped isotopes. Finally, it is expected that the understanding of the genetic relationship between the lacustrine carbonates at the end of the Pre-Salt and the evaporites will provide important inputs for the depositional and diagenetic model of this Santos Basin stratigraphic section, allowing for the evaporitic facies prediction, guiding new technological drilling challenges in frontier exploration areas and contributing to a reduction in geological risk and operating costs.

COMMITTEE MEMBERS:
Interno - 3342517 - ADRIANO DOMINGOS DOS REIS
Interno - 1178074 - GUILHERME DE OLIVEIRA GONCALVES
Presidente - 1658822 - LUCIETH CRUZ VIEIRA
Interno - 2339865 - MARTINO GIORGIONI
Interno - 418662 - ROBERTO VENTURA SANTOS