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Thin-bedded sand-shale sequences frequently exhibit resistivity anisotropy. That is, resistivity measured perpendicular to the bedding (Rv) is significantly higher than the resistivity measured parallel to the bedding (Rh). It is difficult to determine water saturation in these sequences using standard induction logs that respond primarily to Rh, regardless of relative dip angle. If conductive shale laminations are present, the water saturation is over estimated; equivalently, hydrocarbon in place is underestimated.A recently introduced triaxial induction tool provides several 3×3 tensor measurements that are sensitive to Rh, Rv and formation dip. A fast and rigorous inversion of triaxial induction data provides logs of Rh, and Rv without shoulder bed effect, and also provides logs of formation dip. The robustness of the inversion algorithm has been validated with synthetic log data.A petrophysical model has been developed that computes both sand resistivity (Rsand) and shale resistivity (Rshale) from Rh and Rv logs. Fraction of shale, determined using established log interpretation techniques, is an input to the model. Since the induction measurement is relatively deep, the uncertainty in water saturation using the model is greatly reduced compared to interpretation models that use microresistivity logs.Case studies from oilfields around the world demonstrate the utility of triaxial induction measurements for formation evaluation. Data were acquired in a wide variety of borehole and formation environments. These include oil-based mud, waterbase mud, dipping formations, vertical wells, deviated wells, and a wide-range of borehole sizes. Low resistivity pay zones were identified that might otherwise be missed with standard induction logs. Microresistivity images confirmed the presence of thin laminations and confirmed the dip measurements from the triaxial induction.