RETRIEVABLE FORMATION RESISTIVITY TOOL HAVING A SLOTTED COLLAR

摘要

A sonde is movable lengthwise in and relative to tubular structure such as a drill collar; slits extend through the tubular structure; and antennae coils on the sonde come into registration with the slits, for transmitting electromagnetic energy into the underground formation via certain slits, and for receiving such transmitted energy back through other of the slits; for processing.