APPLICATION OF HIGH-RESOLUTION SEQUENCE STRATIGRAPHY TO NORTHWEST HUTTON FIELD, NORTHERN NORTH-SEA - IMPLICATIONS FOR MANAGEMENT OF A MATURE BRENT-GROUP FIELD

The Middle Jurassic Brent Group reservoirs in Northwest Hutton compris e shallow-marine, marginal-marine, and coastal-plain reservoir sandsto nes of both channelized and sheet geometries, The connectivity and pro duction characteristics of these sandstones can be predicted through t he application of high-resolution sequence stratigraphic correlation t echniques. The Broom Formation overlies a basal Brent sequence boundar y and is a lowstand to transgressive systems tract tidal-estuarine com plex. The overlying Rannoch Formation comprises shoreface sands that r epresent a highstand systems tract, The overlying Etive Formation is a multilayer fluvial to estuarine channelized system of near fieldwide development interpreted as incised valley fills, The superjacent Ness Formation is genetically related to the Etive and is the main oil-bear ing interval over much of the field. The Lower Ness comprises mouth-ba r parasequences and is interpreted to be a transgressive systems tract to the Etive lowstand, The Upper Ness is a nonmarine delta plain succ ession, interpreted as a highstand systems tract. Upper Ness channel s ands typically correlate between several wells and are oriented west-e ast. An interval of widespread, stacked channels indicates a change in drainage orientation and is related to a high-frequency relative sea level fall, The uppermost reservoir unit is the Tarbert Formation, rel ated to a further major sequence boundary. Original repeat formation t ester data support a stratigraphically well-connected reservoir model. Compartmentalization exists and is due to stratigraphic layering (lat erally persistent mudstones creating low vertical permeability) and va riable dimensions of channels and valley fills.