A new well-logging tool with tilted-coil can provide azimuthal information about formation and can improve the estimates of formation anisotropy. In this paper, an efficient algorithm is employed to simulate the response of electromagnetic logging tool with tilted-coil antennas in cylindrically stratified anisotropic formations. Firstly, tilted-coils are approximated into tilted magnetic dipoles. Then, we decompose it into three orthonormal components of magnetic dipoles, and the electromagnetic field generated by the three orthonormal components can be solved with the analytic method. Finally, we analyze the response of electromagnetic tool with tilted-coil antennas at different tilted angles and in different borehole environments, such as the responses in anisotropic formations, borehole effects and tool's eccentricity effect.
Read full abstract