Abstract: Multi-component induction measurements are made using a resistivity logging tool in an anistropic earth formation. A subset of the multi-component measurements are inverted to first determine horizontal resistivities. Using the determined horizontal resistivities and another subset of the multi-component measurements, the vertical resistivities are obtained. Results of using the in-phase signals are comparable to those obtained using multifrequency focusing of quadrature signals.

Abstract: Multi-component induction measurements are made using a resistivity logging tool in an anistropic earth formation. A subset of the multi-component measurements are inverted to first determine horizontal resistivities. Using the determined horizontal resistivities and another subset of the multi-component measurements, the vertical resistivities are obtained. Results of using the in-phase signals are comparable to those obtained using multifrequency focusing of quadrature signals.

Abstract: A method is discussed for obtaining resistivity values in a horizontal or highly-deviated wellbore penetrating an anisotropic formation layer. Multi-component data is obtained from the formation layer. An initial value of horizontal and vertical resistivity can be determined by using a whole space model and assuming an isotropic layer. Revised values of the vertical and horizontal resistivities are obtained through a first and second inversion process. A first inversion is performed on the horizontal resistivity, holding a value of vertical resistivity constant. A second inversion is performed on the vertical resistivity, holding a value of horizontal resistivity constant. These inversions are iterated until a desired convergence is achieved.

Abstract: Measurements made by a multicomponent logging tool in a borehole are inverted to obtain horizontal and vertical resistivities of a formation traversed by the borehole. The model includes layers of equal thickness, each layer having a horizontal resistivity and a vertical resistivity. For a vertical borehole, the inversion is done by first iteratively obtaining the horizontal resistivities of the layer using the Hzz component of the data wherein in successive steps of the iteration, the horizontal resistivity for each layer is multiplied by a ratio of a model Hzz output to the measured Hzz. The vertical resistivity model is set equal to the derived horizontal resistivities and the iterative process is repeated using the ratio of the model Hxx output to the measured Hxx. A similar process is used for boreholes with a known inclination. For such an inclined borehole, the two horizontal components Hxx and Hyy are summed to give a horizontal measurement Hxxyy that is independent of tool rotation.