Determination of dip and anisotropy from transient triaxial induction measurements

Abstract

The dip and anisotropy of an anisotropic formation were algebraically determined from the transient triaxial induction data without inversion. The time-dependent apparent dip and the apparent anisotropy, algebraically defined from the triaxial transient induction measurements, were applied in a two-layer formation. The apparent dip yielded the true dip in an anisotropic formation, as well as in layered formations, though it yielded the zero dip in an isotropic formation. At early time the apparent anisotropy yielded the true anisotropy of the layer on which the induction tool was located, and at later time the macroscopic anisotropy for a larger volume of investigation. The distance to the layer interface was identified by the transition time when the apparent dip and the apparent anisotropy change the values.