This study characterizes an Albian carbonate reservoir of oilfield B in the Campos Basin, based on geophysical well logs and laboratory petrophysical data. The use of current approaches to characterize reservoirs allowed us to estimate the porosity, permeability, and water saturation of this reservoir in a more reliable way than when this oilfield was discovered in 1976. To achieve this goal, the cluster analysis for rock typing module of the Interactive Petrophysics software was used to divide the succession into 11 electrofacies. Using log and laboratory data, an equation was derived to determine the porosity and the permeability of each electrofacies through the multiple linear regression technique. The results were compared with different models proposed by other authors, with the best results being found with multiple linear regression. Water saturation, on the other hand, was estimated by the Archie (The electrical resistivity log as an aid in determining some reservoir characteristics, Petroleum Transactions of AIME , 146:54–62, 1942) equation after identifying the cementation coefficient with the Pickett (A review of current techniques for determination of water saturation from logs, Journal of Petroleum Technology 18:1425–1433, 1966) cross plot. Finally, the porosity and permeability data were again used to identify three main flow units in the reservoir through the Winland (Oil accumulation in response to pore size changes, Weyburn field, Saskatchewan. Amoco Production Company Report F72-G-25, 20 p., 1972) graph. To verify the effectiveness of the adopted methodology, it was applied (successfully) in a test well, defining porosity, permeability, water saturation, and flow units, where laboratory data were absent.

Abstract In recent years, stratigraphic and combination traps such as Buzzard (UK North Sea) and Jubilee (Ghana) have attracted much industry attention. Such trap types are generally considered higher risk than structural traps, and understanding them represents a challenge for explorers, as numerous less successful (often amplitude-driven) attempts have demonstrated. Owing to their perceived high risk, stratigraphic traps are often drilled late in a basin's exploration history; however, we assert that consideration of stratigraphic traps should be part of any frontier exploration programme because they occur in all basin types and depositional settings, and allow new plays to be opened up. Additionally, stratigraphic, combination and sub-unconformity traps offer the chance to rejuvenate exploration in mature basins, as recent discoveries like the Edvard Grieg Field (Norwegian North Sea) have shown. Focusing on clastic systems, and using a combination of seismic examples and models, we present two aspects of stratigraphic trap exploration: (1) the regional and local factors that favour the development of stratigraphic trap edges; and (2) a systematic method for defining and risking the trap edges, avoiding the common problem of over-risking. These two methods, used together and applied consistently, allow explorers to focus on the right area of a basin and to risk stratigraphic traps appropriately, for a fair comparison with structural traps.