Analysis of floodplain sedimentation, avulsion style and channelized fluvial sandbody distribution in an upper coastal plain reservoir: Middle Jurassic Ness Formation, Brent Field, UK North Sea
Published:January 01, 2017
Yvette S. Flood, Gary J. Hampson, 2017. "Analysis of floodplain sedimentation, avulsion style and channelized fluvial sandbody distribution in an upper coastal plain reservoir: Middle Jurassic Ness Formation, Brent Field, UK North Sea", Sedimentology of Paralic Reservoirs: Recent Advances, G. J. Hampson, A. D. Reynolds, B. Kostic, M. R. Wells
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Numerical models and recent outcrop case studies of alluvial-to-coastal-plain strata suggest that autogenic avulsion can control the stacking density and architecture of channelized fluvial sandbodies. The application of these models to subsurface well data was tested by the analysis of upper coastal plain deposits of the late Bajocian Ness Formation in the Brent Field reservoir, UK North Sea. These coastal plain deposits accumulated during the progradation and retrogradation of the wave-dominated ‘Brent Delta’. Sedimentological facies analysis and palaeosol characterization in cores were used to interpret the styles of palaeochannel avulsion. These results were then compared with the dimensions and distributions of channelized fluvial sandbodies that had been quantified by spatial statistical tools (lacunarity, Besag’s L function) applied to interpretative correlation panels between closely spaced wells. The results indicate that the distributions of channelized sandbodies may plausibly have been generated by avulsions and that they influence sandbody connectivity and pressure depletion patterns. Intervals of upper coastal plain strata with relatively wide sandbodies that display some clustering in their stratigraphic architecture are associated with a high proportion of avulsions by incision and annexation in core samples. Such intervals display relatively good vertical pressure communication and relatively slow, uniform pressure depletion.
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Sedimentology of Paralic Reservoirs: Recent Advances
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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.