To determine all of the components of in situ stress from core discing, both the directions and magnitudes of the principal in situ stresses must be determined for a disc of a given thickness. In this study, we analyzed the magnitude of tensile stress below an HQ core stub for 11 core lengths using stress conditions under which core discing is likely to occur. Based on the results for the central part of the core, we proposed a linear criterion for core discing, which can be applied to a core of any length. This criterion was in good agreement with an empirical formula obtained previously in laboratory experiments. By combining information on the direction of in situ stress and the linear criterion for core discing, we proposed a method for determining all of the components of in situ stress from core discing under the assumption that vertical stress is given by the overburden stress. This method was applied to discs obtained from a field where hydraulic fracturing was performed to measure horizontal stresses. The results showed that while the magnitudes of the principal horizontal stresses estimated from core discing showed a large scatter, they were similar to those determined by hydraulic fracturing.
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