The Upper Brent Stratigraphy and Reservoir Architecture in the Deep Northern Viking Graben

Abstract

This thesis describes the development of the regressive-to-transgressive shoreline prisms within the Middle Jurassic Tarbert Formation in the Martin Linge-Oseberg west flank and the Valemon-Kvitebjørn area in the Northern North Sea. Three correlations have been built, using 11 facies associations and 9 depositional elements, which comprises 14 facies. The Tarbert Formation has been interpreted to be deposited in a mixed tide and wave energy setting, and has subsequently been divided into the Lower, Middle and Upper Tarbert. The Lower and Upper Tarbert are dominantly wave-dominated, while the Middle Tarbert is tide-dominated. A transition from a more closed wave-dominated bay to a tide dominated estuary and back into a more open wave-dominated bay has been documented. Three lower order sequences have been inferred in the Martin Linge–Oseberg west flank correlation. Each sequence comprises a regressive and a transgressive segment. In the Valemon-Kvitebjørn area 6 higher order sequences are present. Due to the significant expansion of the Tarbert Formation in the southern part of the Rungne sub-basin, fault activity is identified as a major controlling mechanism for thickness variations and facies partitioning. Because the expansion can be noticed as early as in the Lower Tarbert Formation, the initial faulting most likely started before the Tarbert Formation was deposited. More faults became active later during the deposition of the Tarbert Formation, causing the variable thickness and facies shift in the Middle and Upper Tarbert.