Banca de DEFESA: GUILHERME MARTINS DELABRIDA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : GUILHERME MARTINS DELABRIDA
DATE: 25/01/2023
TIME: 09:00
LOCAL: videoconferência
TITLE:

SEISMIC ANALYSIS OF COLD SEEPS AS PROSPECTIVE ZONES ON OFFSHORE BARREIRINHAS BASIN, BRAZILIAN EQUATORIAL MARGIN

KEY WORDS:

Brazilian equatorial margin, leakage/seepage structures, hydrocarbon migration, cold seeps, pockmark, deep-water mounds

PAGES: 120
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUBÁREA: Geofísica
SUMMARY:

The Brazilian equatorial margin (BEM) is an oblique-transform segment with counterparts in the Gulf of Guinea on West Africa. Both margins are inherited from the Pangea breakup and hence opening of the Equatorial Atlantic Ocean. These areas have been studied as new exploratory frontiers and recently gained attention due to petroleum systems found in deep- and ultra-deep waters in both conjugate margins. The strike-slip Barreirinhas Basin, located at the central portion of the BEM, has counterparts with the oil and gas producers Ivory Coast and Tano basins. Nevertheless, no relevant reserves were identified on the Barreirinhas Basin yet, moreover due to the poor study in respect to the petroleum systems, particularly on deep-waters. This present study aims to identify cold seeps localized in shallow strata and associated with hydrocarbon migration, indicating possible hydrocarbon accumulations along the offshore Barreirinhas Basin. Investigation was made through conventional 2D seismic reflection in post-stack time migration with additional use of seismic attributes, including RMS amplitude, instantaneous amplitude, instantaneous frequency, and chaos. These seismic attributes are extensively used in the petroleum industry to reduce exploratory risks by optimizing the conventional seismic lines. The results comprise the identification of cold seeps, in shallow-strata, associated with hydrocarbon migration, including leaking faults, gas chimneys, pockmarks, hydrocarbon-derived diagenetic zone (HRDZ), bottom simulating reflectors (BSR), and deep-water mounds. Regional morphologic and stratigraphic structures constrain the zones of cold seep occurrences formed by fluid leakage and seepage, which indicate petroleum systems. In the eastern lower continental slope and continental rise, regional normal faults and gas chimneys controls cold seep formation. On the central to northern sectors of the continental rise and abyssal plain, several deep-water mounds are linked by large gas chimneys and faults. There are gravitational gliding systems on the western and central portion of the basin, where the extensional domain is characterized by normal faults, negative flower structures, and gas chimneys that produce cold seeps on the outer shelf and upper slope. These structural controls are related to the compressional domain of the lower continental slope and continental rise, where the decollement zone and series of faults and folds are correlated to pockmarks and deep-water mounds. Near to the western compressional domain, igneous intrusions control the development of leaking faults, gas chimneys, bright spots, and pockmarks. These hydrocarbon-derived structures, cold seeps, and pathways of fluid migration in deep-water indicate potential petroleum systems in the Aptian to Turonian-Oligocene tectono-sedimentary sequences in the central sector of the Brazilian Equatorial Margin. However, more refined techniques are needed to confirm the presence of active hydrocarbon seepage and/or storage. Likewise, the Barreirinhas Basin can be a vast field to the petroleum industry and scientific research, with the latter specially focusing in the nature of the HRDZs and deep-water mounds, endowed of great potential for the geobiology.

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