The Grès d’Annot as an analogue for Brazilian Cretaceous sandstone reservoirs: comparing convergent to passive-margin confined turbidites

Abstract

The Eocene deep-water sand-rich deposits of the Grès d’Annot of southern France have been used as outcrop analogues for offshore Cretaceous reservoirs of Campos Basin, southeastern Brazil. The analogy is chiefly based on the sand-rich, confined nature of the two systems. Such application can be questioned as the contrasting geological settings, i.e. convergent versus passive margin, could produce rather different depositional scenarios. Detailed comparison between the two systems permits, however, recognizing additional similarities, and also some differences, whose recognition is important to ensure the correct application of the Grès d’Annot as an analogue for this and other passive-margin reservoirs. Comparative analysis of channel dimensions, facies continuity, and three-dimensional expression suggests that confined sand-rich systems show many similarities in terms of critical reservoir heterogeneity, providing that palaeotopographic control was similar, regardless of the tectonic environment in which they were formed. In addition, contrasts found among sequences in the same tectonic setting suggest that other factors (such as, for example, sand/shale ratio of the sediment input) play an important role in defining reservoir architecture. These observations further suggest that, once similarities and differences are correctly understood, analogue data, even from quite different tectonic settings, may provide a powerful tool for improving subsurface reservoir models.

Seismic Geomorphology and Connectivity of Deepwater Reservoirs

“…These curves were not obtained in the Brushy Canyon Formation or in the Karoo Basin outcrops because the database in these regions, at the time of the study, was considered insufficient. However, adequate geological analogy was found with the outcrops from where the curves have been extracted (from the Annot Sandstone, of southern France -see discussions in Stephen et al 4 and Moraes et al 5 ), despite the fact that these outcrops do not present the same extensions as the ones from the Brushy Canyon Formation or the Karoo Basin.…”

“…Where not possible, such an effect should at least be considered in the development strategy. In addition, the depositional directions also should be taken in consideration, as they commonly introduce areal 5 . The several points raised in this section strongly indicate that the recognition and mapping of architectural elements is an essential step of reservoir characterization, and that this procedure, complemented by the use of outcrop analog data, provides the more adequate method for the building of reservoir models.…”

Link between growth faulting and initiation of a mass transport deposit in the northern Taranaki Basin, New Zealand

“…Figure shows cross‐plots of the MTD within this study relative to examples of published MTD length:width ratios (MeCkel, ). Sixty‐one points represent MTDs obtained from published literature including outcrop, seafloor and subsurface data (Clark & Pickering, ; Gardner & Borer, ; Moraes et al ., ; and those reviewed in MeCkel, ). Figure a shows that the Karewa Fault MTD does not follow the characteristic length/width trend of typical MTDs.…”

Impact of salt-related palaeotopography on the distribution of turbidite reservoirs: Evidence from well-seismic analyses and structural restorations in the Brazilian offshore

“…Outcrops of confined turbidite systems have also been used as analogues for the characterization of subsurface reservoirs (e.g. the Annot sandstone in France; Moraes et al, 2004).…”