Correlation of Triassic to Lower Jurassic sequences, Snorre Field and adjacent areas, northern North Sea

Abstract

The Snorre Field is located within the Tampen Spur on the crest of an uplifted, rotated and eroded fault block which flanks the western margin of the Viking Graben. Reservoir units are the Statfjord Formation (late Rhaetian-Sinemurian) and the continental redbed sequences of the Hegre Group (Scythian-Rhaetian). Log patterns reflect vertical grain size trends associated with the stacking of channel, sheet flood and flood plain deposits. Low-order log sequences represent individual channel or sheet flood units, or channel belt systems that are related to autocyclic processes of channel migration and avulsion. Few low-order log sequences can be correlated confidently at the present well spacing of 2-5 km. Medium- and high-order log sequences, a few tens to a few hundreds of metres thick, reflect depositional cycles that can be correlated over wider areas. These are interpreted as responses to allocyclic mechanisms associated with relative changes in base level and sediment influx. Lithostratigraphic boundaries usually coincide with log sequence boundaries, but discrepancies occur; for example, at the lower boundaries of the Lomvi and Statfjord Formations and at the boundary between the lower and upper members of the Teist Formation. -from Authors