Gas flooding of the Statfjord reservoir, Statfjord Field

Gas has been injected into the Statfjord reservoir in the Statfjord Field for more than ten years. The reservoir is a heterogeneous sandstone reservoir of Jurassic age and is not considered as an ideal candidate for gas injection. The displacement is more gravity stable than originally anticipated, and currently a large gas cap has been established on top of the reservoir. A low residual oil saturation is expected behind the gas front. The gas flood is believed to be a multicontact miscible process. Fluid sampling from the field has shown minor transfer of molecules between the oil and gas phases. An aggressive drainage strategy and frequent well interventions have contributed to a high recovery from the Statfjord reservoir.