Ekofisk time-lapse seismic — a continuous process of improvement

摘要

The Ekofisk oilfield (Figure 1) is located about 300 km south-west of Stavanger in blocks 2/4 and 2/7 of the Norwegian North Sea, where the water depth is about 70 m. It is a late Cretaceous/early Palaeocene anticlinal chalk structure at about 2900-3500 m depth, with a total reservoir thickness of approximately 200 m. There are two reservoirs, the Tor formation and the overlying Ekofisk formation, separated by an impermeable tight zone. The Ekofisk formation contains about two-thirds of the original reserves. Both reservoirs have high porosity (25-45%), but low matrix permeability (0.1-10 mD), and the permeability that exists is largely related to pervasive fracturing.