Determination of rock stress by anelastic strain recovery measurement of an oriented core in the Nittsu region of Japan

摘要

Anelastic strain recovery (ASR) of an oriented andesite core taken from a depth of 4500m MD in a deep well was measured in six independent directions. The recovered anelastic strains were used for a three-dimensional analysis of the directions of the principal in-situ stresses. The directions were in agreement with those determined for the same region using stress relief method. In addition, the predicted principal stress values ranged between those of the major and minor principal stresses which were independently determined by differential strain curve analysis using cores extracted from nearly the same depth in the same well. The results obtained show that the ASR method is well suited to be used to determine in-situ stresses at great depth.