Subsidence of chalk oil reservoirs in North Sea is related to the chalk compaction induced by fluid depletion and by the water ― chalk interaction. A constitutive model is developed in order to take into account these two effects. It is based on frictional - cap elastoplasticity and on the Barcelona unsaturated soil model. Oil ― water ― chalk interaction is modeled through the suction variablse. In a second step, viscous effects are added to the model. After implementation into a finite element code, these tools allow to simulate a waterflooding experiment on a chalk sample. The model appears to reproduce quantitatively and quantitatively the experimental results.
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