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The Hammerfest Basin aquifer is classified as a half open aquifer, comprising the Tubåen, Nordmela and Stø Formations. The aquifer is bounded by the Troms-Finnmark and Ringvassøy-Loppa Fault Complexes in the south and west, and by the Asterias Fault Complex towards the Loppa High. The permeability is highest in the Stø Formation and lowest in the Nordmela Fm, as reflected in the permeability range in the table. The total aquifer volume is significantly higher than the volume of separate prospects, and the lateral connectivity in the Stø Formation is good. Consequently, the calculation of storage capacity in the Stø Formation in the prospects is in most cases based on the assumption that the pore volume of the trap is the limiting factor.
Prospects C and D are structurally defined traps with 4-way closures. No major faults and no signs of gas leakage were observed. The interpretation is based on 2D seismic data with poor coverage; consequently the geometry and size of the structural closures are uncertain. Prospect C has several minor faults cutting through the reservoir. The faults are not believed to offset the primary seal completely, but a lower fractured seal quality is indicated. Well 7122/4-1 was drilled on prospect C and proved a brine filled structure with hydrocarbon shows.
Prospects E and F are interpreted as 4-way closures within the greater Albatross area. The closure of prospect E is fault-bounded to the north. The throw of the fault is larger than the thickness of the primary seal; hence the seal quality is rated lower than the neighbouring structure, prospect F. Prospect E was drilled by well 7221/5-3, which encountered brine with hydrocarbon shows in the Stø and Tubåen Formations. Prospect F has not been drilled and is regarded as a hydrocarbon prospect. The closure is partly bounded by faults with small throws. No gas clouds or other signs of gas leakage have been observed in the seismic data. Prospect F can be an interesting candidate for CO2 storage if water-filled. The storage capacities are based on the volume above spill point. Prospects E and F are located between Snøhvit and Melkøya, only a few km away from the pipeline.
Prospect G is defined as a large structural closure with several culminations. The structure is bounded by the Troms-Finnmark Fault Complex, and a deep spill point depends on a fault seal towards the Triassic rocks in the Troms-Finnmark Platform. Two wells have been drilled within the structural closure, 7120/12-5 was dry, 7120/12-3 was a gas discovery in the Stø Formation. South of the structure, 7120/12-1 encountered brine with hydrocarbon shows, and 7120/12-2 proved gas/condensate. The capacity of the trap is based on the volume above the spill point, but with a low storage efficiency because injected CO2 plumes must not interfere with the accumulations of natural gas.
Prospect H is a complex structure with many fault blocks, bounded to the south by the Troms-Finnmark Fault Complex. The volume of the structure is calculated based on a deep spill point which depends on fault seal. The prospect is covered by 3D seismic data, but the seismic data quality is low in large areas due to gas clouds and shallow gas. Within the structure, three wells have been drilled without encountering movable hydrocarbons. 7119/12-4 and 7120/10-1 were dry, while shows were observed in 7119/12-2 throughout the Middle Jurassic to Upper Triassic.