GEMS TruTracker®

The TruTracker surface locating system provides accurate trenchless drilling when magnetic interference is present.

The system is used in conjunction with a magnetic steering tool run in the drillstring.

The TruTracker Guidance System is the industry standard for trenchless construction by providing accurate location of the bit regardless of magnetic interference. TruTracker measures lateral and vertical position to ±0.2 ft. per 10 ft. of borehole depth (or, ±2%).

TruTracker
The TruTracker system is utilized when magnetic interference is encountered in operations such as rivercrossings or other trenchless construction projects. Items near the borehole, such as railroad tracks, power line towers and other pipelines can corrupt the directional readings in the downhole steering probe.

Operation
The TruTracker system produces a DC power signal on surface to accurately define the position of the subsurface drillstring while drilling. The signal produces a magnetic field to effectively override the influence of the magnetic interference on the downhole steering probe. Then by measuring the known parameters and geometry of the TruTracker field with the steering probe, the probe's location can be found through triangulation.

Set Up
A wire loop is laid out on surface to form a coil centered over the proposed borehole path as illustrated above. The geometry of the coil and elevation relative to the borehole path are measured precisely and staked. A DC power source, such as a welding machine, is connected to the ends of the loop, along with a current measuring device.

Taking a Survey
At an appropriate point during drilling, such as a pipe connection, drilling is stopped to take a TruTracker survey or "shot." The DC power source is turned on, creating a magnetic field under the loop. A proprietary software program generates a model of the magnetic field distribution around the loop, comparing the direction and intensity of the field at particular points to the corresponding data measured by the steering probe. When the two sets of data match, and other qualifying data are within specification, a survey is accepted. The current is then reversed and measurements are taken again as an additional qualification.

The program assumes the probe position is along the centered, proposed path. By measuring the direction from the probe to the coil, the software triangulates drillhead position left or right from center and generates a precise plot of the borehole path.