Three aspects of reservoir compaction/subsidence simulation for Ekofisk are addressed: (i) stress paths in the reservoir during depletion, (ii) impact of porosity heterogeneities in reservoir chalk on scaling laboratory compaction data to field behavior, and (iii) methods for treating the behavior of the overburden in a finite element simulator. Specially created finite element models were used for the first two issues. Results indicate that geometry has a major impact on stress path. Results of the scaling analysis indicate that porosity heterogeneities cause a block of chalk comprised of numerous cells with different porosities to appear strong when internal shear failure is not allowed, but to appear weak when it is allowed. The discussion of the overburden behavior concentrates on field observations, interpretations of these observations, and methods used to represent them in a simulator.

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