Abstract
Thermally-induced, non-reversible compaction with volumetric strains of up to more than 1% has been observed in laboratory compaction tests with core plugs of several different shales. While thermallyinduced compaction is known to occur in unconsolidated clays, relatively large compaction of caprock shales at temperatures even below in-situ temperature was rather unexpected. The observed thermally-induced compaction follows a creep-like behavior and is accompanied by increases in ultrasonic velocities.