“…In most cases, the spacing between transmitters and receivers is less than 1 m and the frequency ranges from hundreds of kilohertz to a few megahertz, which limits the capability of edge detection. One type of electromagnetic boundary detection logging tool, Schlumberger's Periscope and Geosphere, uses a tilted antenna (Li et al, 2005;Omeragic et al, 2006;Antonsen et al, 2014;Seydoux et al, 2014;Zhu et al, 2021;Wu et al, 2022). The other type, by AziTrak and ViziTrak of Baker Hughes, uses an orthogonal antenna (Bell et al, 2006;Wang et al, 2007;Fang et al, 2008;Rabinovich et al, 2011).…”