In past columns we have discussed the use of horizontal directional drilling (HDD) for remediation well installations, soil sampling using HDD, and HDD drilling fluids and containment. In this article, we look at another of the unique aspects of the technology — locating and navigation. After all, with “directional” as a major part of the technology’s name, you might assume there are ways to figure out where you are and where you’re going when drilling an HDD well.
Terminology for HDD locating systems can be very confusing, even without going into the technology itself. Walkover vs. wireline, GST, grids, coils, and sondes — what do they all mean?