f Reservoir monitoring using the VSP technique. A case study in the Oseberg field

The Oseberg Field is located in the Norwegian North Sea blocks 30/6 and 30/9, approximately 140 km northwest of Bergen with a maximum extension of 26 km north-south and a maximum width of 6 km east-west . The Field Game on stream in December 1988 . The Field comprises three major easterly rotated fault blocks Galled Alpha, Gamma and Alpha North . Hydrocarbons occur within the sandstones of the deltaic Middle Jurassic Brent Group . The reservoir sands exhibits excellent reservoir quality with porosities around 20-25% and permeabilities ranging up to several darcys . The structural dip is normally 6-10 ° east-northwest and the gross Brent thickness varies between 40 and 200 m .