Nearly 10 years have elapsed since the first engineering prototype of the multi-component induction tool was built and tested. During this time, we have progressed significantly from the first experimental logs run in simple straight wells to a mature service where the tool is used daily in every possible environment. Jointly developed by Baker Atlas and Shell, the 3D Explorer instrument (3DEX) was originally designed for a low-resistivity pay evaluation in laminated sandshale sequences based on detecting resistivity anisotropy. Numerous case studies have demonstrated that the tool reduces uncertainties and often leads to the identification of hundreds of feet of additional pay. At the same time, significant improvements in the multicomponent measurement accuracy and advances in the theory and in data processing have extended the environment in which the tool can be run reliably and have allowed us, in addition to resistivity anisotropy, to determine accurate structural formation dip and azimuth. This application becomes especially important in environments where dipmeter and imaging devices experience problems (OBM, rugose boreholes, soft formations). In several cases, 3DEX was successfully used in evaluation of fractured reservoirs. The multi-component induction tool is comprised of three pairs of mutually orthogonal transmitter-receivers measuring all nine magnetic field components at 10 different frequencies. The acquired data are sensitive to formation anisotropy; however, the response of the tool is highly non-linear with respect to formation parameters and very sensitive to the near-borehole environment. We introduced new processing technology based on multi-frequency focusing (MFF) that allows us to reduce environmental effects and simplify the data dependence on the formation parameters. After MFF, a simple 1-D vertical layered model can be utilized for the data interpretation because near-zone effects have been effectively removed. Our experience shows that often interpretation based on simple models is better than non-unique 3D inversion. Also, MFF responses provide deep measurements that are an excellent source for structural formation dips. Azimuthal sensitivity of the multi-component measurements provides the foundation for their use in fracture analysis. We present in the paper several successful case studies of low resistivity pay evaluation, processing for formation dip and azimuth, and for fracture characterization. We also review common practices of using resistivity anisotropy in petrophysical analysis.
