Vertical leakage mechanism

The interplay between reservoir and cap rock pore-pressures and vertical leakage mechanisms for the field has been further assessed by analysing the reservoir pore-pressure situation at the apex (i.e., the weak point ) of each hydraulic compartment (Fig. 13), and by relating the apex reservoir pore-pressures to the corresponding minimum fracture pressures of the cap rock (Fig. 14). The fact that the Spekk Formation represents both the main source rock and cap rock for the Njord Field is a key aspect in these considerations. 

The relationships between the pore-pressures of the Jurassic reservoirs, the estimated overburden pore pressures and the formation integrity trends of the structure are taken to suggest that capillary entry pressures (membrane seal failure), possibly in combination with cap rock microfracturing, are the main controlling mechanisms for vertical leakage. 

The mechanisms and observations discussed above may indicate that the Njord reservoirs, particularly the Tilje and He reservoirs in hydraulic compartment II and the Tilje reservoir in hydraulic compartment III at present hold close to their maximum hydrocarbon columns, which further implies active present day recharging of these reservoirs compensating for the vertical leakage. 

The reactor coolant pump is a vertical, single speed (1500 rpm), bottom suction, horizontal discharge casing unit with controlled leakage mechanical shaft seals and driven by a... 

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