Reservoir characterization of Sognefjord and Fensfjord formations across Gjøa field, North Sea, Norway

Abstract

The Gjøa field was discovered in 1989 and first production started in 2010 located about 40 kilometers north of the Fram field. The reservoir contains gas above a relatively thin oil zone in Jurassic sandstones in the Viking, Brent and Dunlin Groups. The main reservoir units of Gjøa field are Fensfjord and Sognefjord formations, Viking group. The stratigraphic evolution from Callovian to Kimmeridgian Fensfjord and Sognefjord formations in the greater Gjøa field hasn’t been subject of previous work, but they form perspective reservoir intervals on neighborhood areas like Troll and Brage fields. The Fensfjord and Sognefjord formations interpreted as tide, wave and fluvial dominated delta environment. The facies association indicates shelfal, pro-delta, delta-front, delta-plain, shoreface and estuarine depositional environments. The seismic interpretation of the study area revealed changes in structural regimes during deposition of Fensfjord and Sognefjord formations. The N-S extension changed to NW-SE in E. Oxfordian – M. Oxfordian periods, which highly affected the depositional processes of Fensfjord and Sognefjord formations. The main goal of this study is an integration of data analysis and provided conceptual geological model for tectono-stratigraphic evolution of Gjøa field from Callovian to Kimmeridgian period.