Abstract
The objective of the present project was to study how high temperatures affect the different mechanical parameters of chalks. Two types of high porosity outcrop chalks were used. Several series of Brazilian, uniaxial and triaxial compressive tests have been performed at both ambient and reservoir temperature, 130 °C the Ekofisk temperature. Both water and glycol were used as saturating fluids, and in addition some test series on dry chalk were included. The results so far show that the yield envelope has a tendency to shrink with increasing temperature. Both cohesion and the hydrostatic yield stress are typically reduced about 20 % in going from 20 to 130 °C, but the magnitude of this reduction may be chalk type dependent. For the friction angle there are some indications of a slight increase with increasing temperature, but some results point in the opposite direction. Experiments with dry chalk show some degree of strengthening, probably due to drying effects.
