Jurassic Reservoir Distribution and Environment of Deposition across Eastern Part of Johan Sverdrup Field, South Viking Graben, North Sea

Abstract

The South Viking Graben (SVG) is an asymmetric graben located in the Northern North Sea has been the focus for oil exploration for many years. The SVG includes hydrocarbon plays of Triassic age, Jurassic, Paleocene and Supra Paleocene. During the Triassic and Jurassic age halokinesis of the Zechstein Group occurred due to the structural and stratigraphic developments in the Utsira High margins. Due to the salt withdrawal accommodation place was created that was filled by deposits of fluvial, alluvial and delta plain sediments.The study area is located in the South Viking Graben at Avaldsnes High in the eastern part of the Johan Sverdrup Filed and is one of the five major Fields ever discovered on Norwegian Continental Shelf. The Field is under three production licenses PL501, PL265 and PL502. This study will focus on the distribution and environment of deposition of Jurassic sediments on the Avaldsnes High in the Jurassic time. The data available for the study to be carried consist of 3D Seismic cube, well cores and well log data. The Seismic data and the well data in combination can give the distribution of the sediments in the area with well tops the interpretation of the sediments is much simple. The core data give much more insight into the lithology, grain size, fossils and sedimentary structures present in the rocks within the area and can be used to estimate the environment of deposition. This study involves interpretation of 3d seismic cube, well correlations, correlation between well data and seismic data and core logs created from the well cores had been used to determine the distribution of the Jurassic strata. The Jurassic strata, specifically the Intra Draupne sandstone which is the main reservoir in the study area and Draupne formation mainly thin towards the Avaldsnes High. To comprehend this surface maps, thickness maps and attribute maps had been created. The environment of deposition ranges from fluvial, alluvial for the lower Jurassic to reworked fan delta for the Intra Draupne sandstone to offshore marine for the Draupne Shale.