Mining Publication: Borehole Location System Concept Demonstration Tests

This report describes the feasibility test of an electromagnetic method for locating boreholes, with or without casing, that have been drilled in conjunction with mining operations but without precisely known locations with respect to the tunnel. The first tests, conducted in cooperation with the Kerr-McGee Corp. near Gallup, new Mexico, in September 1977, demonstrated that accuracies of better than +/-5 pct of range and +/-1 deg. of bearing can be achieved with a simple system and setup. Subsequent tests on a horizontally drilled pipeline river crossing application, by Titan Contractors of Sacramento, California, in January 1978, demonstrated that accuracies of better than 0.5 pct of range and a few tenths of 1 deg. of bearing can be achieved by using refined techniques. The demonstration tests were done at ranges on the order of 100 to 200 feet, but the method is capable of working at much greater distances.