Observations of borehole breakouts and tensile wall-fractures in deviated boreholes: A technique to constrain in situ stress and rock strength

In this study we demonstrate the relationship between compressive and tensile failures of inclined wellbores and the tectonic stress field. We present illustrative polar diagrams from which one can determine the orientation and tendency for borehole failure as a function of the borehole orientation and the stress field. In the case of borehole breakouts, we propose a technique to constrain the magnitude and orientation of SHmax (as well as to estimate the effective in situ rock strength) from the orientation of breakouts in deviated boreholes. The method is based on the assumption that an estimate of the least principal stress is available from leak-off tests or hydrofracs, the overburden stress is obtained…