Patent ID: 9207342
Filing Date: 2015-12-08
Classification: G01V

Abstract:
1. A method for determining a shear wave velocity of a transversely isotropic region of an earth formation traversed by a wellbore with a non-zero relative dip angle between a longitudinal axis of the wellbore and an axis of symmetry of the transversely isotropic region, the method comprising: measuring, with a sonic tool for which the orientation is known, for at least one depth in the wellbore, a quasi-shear velocity in the transversely isotropic region with polarisations orthogonal to the longitudinal axis of the wellbore to obtain a measured quasi-shear velocity; and determining, using a computer, a shear wave velocity for propagation in a direction along the axis of symmetry of the transversely isotropic region as a function of the measured quasi-shear velocity, anisotropy parameters δ and ε of the formation, a compression wave velocity along the axis of symmetry, and the relative dip angle for at least one depth, wherein the shear wave velocity is used to identify one or more properties of the earth formation.