Simulation of the extension behavior of a hydraulically induced crack by use of brittle epoxy specimens.

The extension behaviour of a hydraulically induced crack under the simplified conditions of tectonic stresses was simulated experimentally by use of brittle epoxy specimens with boreholes. The results were described by means of linear elastic fracture mechanics, where a criterion for the onset of crack extension is a critical tensile stress at a characteristic distance deduced from the experimental results. Based upon the criterion with a maximum stress criterion for fracture angles, a predictive procedure for breakdown pressure and fracture angles during hydraulic fracturing was proposed.