Structural and stratigraphic feature delineation and facies distribution using seismic attributes and well log analysis applied to a Brazilian carbonate field

Abstract

Identification of structural and stratigraphic components within a hydrocarbon reservoir is essential for the construction of geologic models that represent the facies distribution as accurately as possible. Such construction may represent a challenge for ancient carbonate reservoirs, which exhibit greater heterogeneity than siliciclastic reservoirs. We developed a workflow that incorporated seismic attribute analysis and well log data to highlight structural and architectural elements with the benefit of the understanding the distribution of facies in this features in an Albian offshore carbonate reservoir in Brazil. The proposed workflow combined incoherence, sweetness, and a new approach of spectral decomposition to delineate the main structural and architectural elements in the field. Well log facies and modern analog analyses were used to support the architectural elements’ interpretation. Joulters Cays is an oolitic shoal in the Bahamas that provided a modern analog for the field in study. Three main fault systems, responsible for the rollover structure of the field, were detected with the incoherence attribute. The workflow allowed the interpretation of four main architectural elements in the field: (1) tidal channels, (2) carbonate shoals, (3) reef, and (4) lagoons. Tidal channels and lagoons are mainly composed by wackestone. Carbonate shoals are primarily composed by grainstone with secondary packstone, while the reef crest is composed by packstone. Sequential indicator simulation (SIS) of well log facies supported these observations. The highlighted architectural elements could be helpful for the construction of a conceptual model of the field or useful as a training image for multiple-point statistics because SIS of well log facies does not define geologic bodies.