Multiattribute framework analysis for the identification of carbonate mounds in the Brazilian presalt zone

Abstract

Carbonate mounds, as described herein, often present seismic characteristics such as low amplitude and a high density of faults and fractures, which can easily be oversampled and blur other rock features in simple geobody extraction processes. We have developed a workflow for combining geometric attributes and hybrid spectral decomposition (HSD) to efficiently identify good-quality reservoirs in carbonate mounds within the complex environment of the Brazilian presalt zone. To better identify these reservoirs within the seismic volume of carbonate mounds, we divide our methodology into four stages: seismic data acquisition and processing overview, preconditioning of seismic data using structural-oriented filtering and imaging enhancement, calculation of seismic attributes, and classification of seismic facies. Although coherence and curvature attributes are often used to identify high-density fault and fracture zones, representing one of the most important features of carbonate mounds, HSD is necessary to discriminate low-amplitude carbonate mounds (good reservoir quality) from low-amplitude clay zones (nonreservoir). Finally, we use a multiattribute facies classification to generate a geologically significant outcome and to guide a final geobody extraction that is calibrated by well data and that can be used as a spatial indicator of the distribution of good reservoir quality for static modeling.

Massive seafloor mounds depict potential for seafloor mineral deposits in the Great South Basin (GSB) offshore New Zealand

“…Although, the seafloor mounds show some similarities with methane-derived carbonate mounds such as high reflectivity and by being underlain by poorly imaged zones 61 , 62 . However, their geometries, large sizes, lack of internal layering, and sharp boundaries signify that they are unlikely to have evolved mainly as methane-derived carbonates on the seafloor.…”

Understanding the relationship between acoustic impedance and porosity in a presalt carbonate reservoir of the Santos Basin

“…Acoustic and elastic inversions are recurrent themes, as well as the use of impedance volumes for modeling reservoir properties, such as porosity and facies classification (Teixeira et al, 2017;Dias et al, 2019;Peçanha et al, 2019;Penna et al, 2019;Penna and Lupinacci, 2021). Acoustic impedance data has also been frequently used for the classification of multi-attribute seismic facies in presalt carbonate reservoirs (Jesus et al, 2019;Ferreira et al, 2019;Ferreira et al, 2021).…”

Borehole image analyses at presalt carbonate reservoirs of the Mero Field, Santos Basin

“…The exploratory and production activities in presalt of the Santos Basin has brought great technological and scientific challenges due to the distance to the coast of these fields, their ultra-deep waters location, the existence of thick salt layer above the reservoirs and to a great heterogeneity of carbonate reservoirs (Karner and Gamboa, 2007;Jesus et al, 2019).…”