Detection of Borehole Currents in Well Logging

摘要

Methods and apparatus for detecting and monitoring the borehole effect in subsurface measurements. Toroidal sensor configurations address the undesired axial electric currents that travel along the borehole when antennas with tilted or transverse axes are used to make electromagnetic measurements. Embodiments use currents measured along the instrument to determine the quality of measured logs, the borehole size, and instrument position or orientation within the borehole.