Stratigraphic architecture of the Knarr Field, Norwegian North Sea: sedimentology and biostratigraphy of an evolving tide- to wave-dominated shoreline system
James M. Churchill, Matthew T. Poole, Silje S. Skarpeid, Matthew I. Wakefield, 2017. "Stratigraphic architecture of the Knarr Field, Norwegian North Sea: sedimentology and biostratigraphy of an evolving tide- to wave-dominated shoreline system", Sedimentology of Paralic Reservoirs: Recent Advances, G. J. Hampson, A. D. Reynolds, B. Kostic, M. R. Wells
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The Knarr Field is located on the Tampen Spur, Norwegian continental shelf and was discovered in 2008 by the Jordbær well (34/3-1S), with additional resources later added to the field by the Jordbær Vest well (34/3-3S) in 2011. Within the Knarr Field, the Cook Formation is informally divided into the Lower Cook and Upper Cook successions and appears to have prograded from east to west. The Lower Cook consists of Sands 1, 2 and 3 and the Upper Cook consists of Sands 4 and 5, with the sands separated by intraformational mudstones that are commonly chronostratigraphically constrained; the J15 maximum flooding surface separates the Lower and Upper Cook. The tide-dominated Lower Cook is notably heterolithic, with intricate intercalations of sandstone and mudrock lithologies representing tidal channel, tidal bar and intertidal bar facies. The Upper Cook represents a series of coarsening-upwards cycles that displays the systematic changes in facies and ichnology expected for a shoreface succession, consisting of offshore, offshore transition zone and shoreface facies. Palynomorphs confirm these observations and suggest that the Lower Cook was deposited in brackish-water conditions, whereas the presence of more marine fossils in the Upper Cook suggests an increase in marine influence. The integration of the sedimentology and biostratigraphy described herein enabled the establishment of a robust reservoir zonation that has been utilized during the development and ongoing exploitation of the Knarr Field.
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Paralic reservoirs reflect a range of depositional environments including deltas, shoreline-shelf systems and estuaries. They provide the backbone of production in many mature basins, and contribute significantly to global conventional hydrocarbon production. However, the range of environments, together with relative sea-level and sediment supply changes, result in significant variability in their stratigraphic architecture and sedimentological heterogeneity, which translates into complex patterns of reservoir distribution and production that are challenging to predict, optimize and manage.
This volume presents new research and developments in established approaches to the exploration and production of paralic reservoirs. The 13 papers in the volume are grouped into three thematic sections, which address: the sedimentological characterization of paralic reservoirs using subsurface data; lithological heterogeneity in paralic depositional systems arising from the influence of tidal currents; and paralic reservoir analogue studies of modern sediments and ancient outcrops. The volume demonstrates that heterogeneity in paralic reservoirs is increasingly well understood at all scales, but highlights gaps in our knowledge and areas of current research.