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The Barcellona Pozzo di Gotto Basin of northeastern Sicily, central Mediterranean, is a Plio-Pleistocene peri-Tyrrhenian shelf embayment that formed by the collapse and marine inundation of bedrock fault-blocks in response to regional tectonic extension. The study focuses on the well-developed transgressive systems tract of the lower bay-fill sequence. This succession of middle Pliocene to Lower Pleistocene marine deposits has a mixed siliciclastic to bioclastic composition and is ~73 m thick in mid-bay outcrop section. The deposits are sandy to silty facies indicating a wavedominated bay rich in suspended sediment and influenced by storms and tidal currents. Facies associations represent upper and lower shoreface, offshore-transition and mid-bay offshore zones. The abundance of silty to sandy suspension is attributed to the entrapment of fine sediment entrained by storms and tides and possibly derived from nearby streams. The supply of sediment from the bay's shoreline zone probably combined with fine-grained sediment drift from offshore areas, as is also suggested by admixtures of outer circalittoral benthic microfauna. Facies-based estimates indicate a water depth of ≤ 25 m for the mid-bay area, with a mean depth of ~10 m for fairweather wave base and ~15-16 m for storm wave base. The shallow bay hosted circalittoral benthic fauna typical of deeper water Mediterranean shelves, which can be attributed to the high turbidity of the bay water (limited light penetration).The stratigraphic organization of the facies associations and their fauna assemblages reveals that the succession consists of six parasequences, or transgressive-regressive cycles, bounded by marine flooding surfaces and showing an overall deepening upward trend. The parasequences are 4-17 m thick, and some include well-developed transgressive deposits and also a relatively thick mid-cycle condensation zone. The latter indicates a prolonged balance between the rates of accommodation development and its filling by slow aggradation. Palaeoecological and taphonomic criteria defining a condensation maximum allow the maximum flooding surface to be identified, typically in the upper part of the mid-cycle condensation zone. The parasequences have time spans of ~300 kyr and correlate with the 4th-order regional sequences recognized in the central Mediterranean. Accordingly, they are inferred to be the local equivalents of these high-frequency sequences, owing their facies architecture to a relatively high rate of tectonic subsidence in the peri-Tyrrhenian coastal region of northern Sicily. These would thus be type 2 sequences involving little or no fall in relative sea level and hence developed as parasequences. The integration of sedimentological, biostratigraphic, palaeoecological and taphonomic data proves to be a powerful method for high-resolution sequence stratigraphy and palaeoenvironment reconstruction, including sediment dynamics, palaeogeography and bathymetric changes.

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Models of hydrocarbon reservoirs are often used to support management decisions about field development and redevelopment. Typical modelling workflows result in a reservoir and simulation model with a property distribution generally comparable to the well data, and this is often considered sufficient. The current study tests this assumption on the fluvial reservoir in the Upper Lunde Member of the Snorre Field where sedimentary heterogeneities at multiple scales influence reservoir properties such as porosity and permeability. This work shows that, by describing and modelling the sedimentary heterogeneities at several length scales in the reservoir, and by using a flow-based local upscaling method, the resulting porosity and permeability distribution at the scale of the reservoir and simulation model are significantly different from porosity and permeability distribution at the well data scale; the variance tends to reduce and, for permeability, the distribution type is changed from log-normal to normal. Reservoir property distributions based on multiscale modelling, sensitive to the representative elementary volumes for permeability, and upscaled in a realistic sedimentological framework, give a better representation of the effective permeability architecture.

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