Evaluation of Mechanical Strength of a Barents Sea Shale by Applying the Most Common Failure Criteria

Caprock seals are formations that prevent the migration of hydrocarbon and storage CO2 to the surrounding formations. Shales and mudstones are most abundant formations in the sedimentary basin that can be found as caprock seals because of their low permeabilities. The most important mechanical parameter of the caprocks is the main principal stress that has crucial importance in exact determination of rock strength, fracture calculations and failure criteria. In this study, the most common failure criteria have been applied to analyze the triaxial test data that are obtained from geomechanical tests performed on the Hekkingen shales from the Barents Sea. The Hekkingen Formation consists of brownish-grey to very dark grey shale and claystone with occasional thin interbeds of limestone, dolomite, siltstone and sandstone. The core samples belonging to the Hekkingen Formation are selected from two depth intervals and are named as G1 and G2 (Table 1).