--> Abstract: Siliciclastic Sandstones in Volcanic Basins, Control from Deposition, Reservoir Quality and Distribution in the Rosebank Field, West of Shetlands, North West Atlantic Margin, by Dag Helland-Hansen and Louise Duncan; #90082 (2008)

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Siliciclastic Sandstones in Volcanic Basins, Control from Deposition, Reservoir Quality and Distribution in the Rosebank Field, West of Shetlands, North West Atlantic Margin

Dag Helland-Hansen and Louise Duncan
Value Creation, Chevron Upstream Europe, Aberdeen, United Kingdom

The Rosebank field, West of Shetlands in the UK, has it reservoir intervals in fluvial to shallow marine sandstones deposited contemporary with basaltic lava flows and their associated erosion product, volcanoclastics.

The volcanic rocks impacts the in place volumes and recovery efficiency of the field in several manners.

1.The volcanoclastics constitutes the seal mechanism of the reservoir
2.The basaltic lava flows form the paleo-landscapes for which the reservoir sandstones were deposited on top and hence indirectly control the reservoir architecture.
3.The fluvial to shallow marine depositional system consists of both volcanoclastics (erosion material from lava) and siliciclastic rocks with rocktype depending upon the hinterland of each river system feeding the sub-basin.
●The volcanoclastic sands have reservoir qualities ranging from poor to medium porosity, with pre-dominantly poor but occasionally medium permeability.
●The siliclastic reservoirs are very clean with medium porosity and very high permeability.

Hence, describing and understanding the interaction of the different rocktypes is therefore crucial for resource estimation, field planning and later production optimisation.

This paper will focus on the current understanding of these processes and how they are interpreted/mapped by integrating paleo-landscapes from seismic data with sedimentological interpretation from elogs, FMI and cores as input into reservoir modelling exercises.

AAPG International Conference and Exhibition, Cape Town, South Africa 2008 © AAPG Search and Discovery