DEPOSITIONAL CHARACTERISTICS OF THE RESERVOIR IN BRENT GROUP, NORTH SEA BASIN

The reservoirs in the Brent Group were studied in this paper, based on core,well logging and diagenetic data. The facies distribution of the Brent Group show a pattern from coastal plain-proximal delta-mouth bar/upper shoreface-distal delta-mouth bar/lower shoreface-offshore marine from south to north. The Broom and the Tarbert Formations are transgressive, tide influenced deposits, while the Rannoch, Etive and Ness Formations are progradational deltaic deposits. There are four sequences in the Brent Group. Each of them is composed of transgressive systems tract and high systems tract. According to sequence stratigraphical analysis, the Tarbert Formation is divided into three units (Tarbert 1, 2 and 3), while the Ness Formation consists of two (Ness 1 and 2). Reservoir properties are controlled by both depositional facies and diagenetic events. High quality reservoirs are mainly formed in deltaic, costal plain environments and distributary channels. Diagenetic events effect reservoir properties either in a constructive way as the uplift-related diagenesis or in a destructive way as the burial diagenesis.