Managing Reservoir Uncertainty after 5 years of field life - Britannia Field

The Britannia reservoir consists of deep-water sandstones of mass flow origin, ranging from high density 'clean' turbidites to non-reservoir facies consisting of debris and slurry flows. Britannia reservoir models rely on over 20,000 ft of core to define the reservoir zonation and facies scheme within the static reservoir model. Recent core-based reservoir studies, including a refinement of the depositional models for upper reservoir Zones 50, 45, and 40, fault seal property evaluation, and detailed diagenetic studies, have further benefited the earth model. A rigorous re-correlation study based on biostratigraphy and geochemical chemostratigraphy have led to refined flow unit definition. The main rock types in the Britannia field are S3 Clean, Banded, and Mixed Slurry Sandstones. Each of these has its own particular petrophysical characteristics that decrease in reservoir quality as listed above. Therefore it is essential to understand each rock type's depositional and sedimentary architecture. In addition, remobilisation of sediments means that the initial depositional orientation may not necessarily reflect resultant slump orientation. Cores from the Zone 40 sandstone are displayed together with well crosssections to demonstrate variations in gross lithological distributions, both geographically and stratigraphically.