A Borehole Imaging Method Using Electromagnetic Short Pulse in Oil-Based Mud

摘要

A borehole imaging method for nonconductive fluid application using a high-frequency electromagnetic (EM) short pulse is introduced in this letter. The pulsed borehole imaging system offers more advantages when compared with conventional dielectric or resistivity imaging tools. The continuous measurement in a wideband spectrum improves accuracy and provides comprehensive well-bore formation analysis information. A high resolution in both vertical and horizontal directions for well-bore cracks, rugosity, and dielectric dispersion of formations can be obtained by radiating an EM pulse signal with a center frequency of 1.2 GHz into a well-bore via a wideband antenna system. This design has been proven to work effectively in oil-based mud and may be used as an alternative tool for logging while drilling imaging applications. By using the transmission line matrix method, numerical simulation results are presented to verify the performance of the proposed EM pulse imaging system. An improved wideband bow-tie antenna is designed for a proposed multispacing EM pulsed imaging system as well.