Patent attributes
Determination of in-situ rock yield stress state of a geological formation surrounding a borehole includes determining a profile for each of an axial effective, a radial effective, and a hoop effective stress within at least one axial plane containing a borehole axis. A predicted radial shear response radial profile is calculated from the effective stresses within the at least one axial plane. A measurement-based estimate of a shear response radial profile within the at least one axial plane is determined from measured data. A maximum radial distance at which a difference between the predicted and measurement-based shear response radial profiles is identified within the at least one axial plane as being greater than a difference threshold. The respective axial, radial, and hoop stresses, are determined at the identified maximum radial distance. The identified stresses are indicative of an in-situ yield stress state of the rock.
