ABSTRACT: Based on our experimental observations, we developed a numerical model of borehole breakout growth in Alabama limestone. For given states of far-field stress breakout shape and dimensions were obtained by simulating the episodic nature of the spalling process and utilizing a rock strength-size effect determined for boreholes of differing radii. These geometric characteristics of the simulated breakouts correctly matched our experimentally produced ones. The results suggest a means to estimate one of the principal in situ horizontal stresses when the other principal stress is known and breakout dimensions are logged.

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