Análise de sismossequências na Seção Drifte da porção offshore da bacia de Barreirinhas, margem equatorial brasileira

Abstract

Important discoveries made over recent years in the South American (Zaedyus discovery) and African (Jubilee Field) equatorial margins opened new perspectives in the exploration of the Brazilian equatorial margin, particularly for the Barreirinhas Basin. The objective of this study is a first seismic analysis approach for the Drift section of Barreirinhas Basin, in deep water areas, based on the identification, correlation and mapping of the seismic facies, horizons and sequences. The few stratigraphic data available together with the lack of stratigraphic interpretations in the studied area make this study challenging. Five 2D depth seismic lines (Pre-Stack Depth Migration) dip oriented and one strike oriented are located in an approximately 1100km2 area, in the offshore Barreirinhas Basin, were interpreted using Petrel (Schlumberger), and its applications. The analysis of seismic characters, impedance contrast, reflectors’ patterns, and sequence geometries showed nine seismic facies, and ten seismic horizons, which seven of them limit six seismic sequences. Geometries identified by isopach maps of the sequences reveals a stratigraphic pattern of aggradational (seismic sequence 1) to retrogradational (seismic sequences 2, and 3) to progradational (seismic sequences 4 and 5) and finally to retrogradational (seismic sequence 6) which can be associated to transgressive-regressive cycles which allowed attemptive correlation to depositional sequences in the onshore previously proposed by literature