Why Directional drilling?
Normally the raise boring technique produces pilot holes with deviations between 0.5 - 1.0 % of pilot hole length. In most cases this is acceptable, but in some applications the need for a straight, controlled hole is critical (i.e. hoist shafts, elevator shafts or pipe shafts). We offer the following products to be able to guarantee tolerances within 0.2% of pilot hole lengths.
The Micon R
ystem (RVDS) is a directional tool that was designed by the German company Micon in 1994-95 and has been tested in the field since November 1994 by us. With the RVDS tool it is possible to guarantee straight holes for standard raise boring diameters (12 1/4", 13 3/4" or 15") without changing the normal raise boring drilling parameters.
The tool is an automatic steering-system for drilling vertical holes. Based on measured values of the two-axis inclination sensors the deviation from vertical course is determined. Exceeding permissible variation activates the hydraulic steering system. Extendible stabilizer ribs generate radial forces and work against the angle build-up. Simultaneously the inclination data are transmitted by mud pulsing (water) to the surface. The tool is specially designed for mining applications, but it can also used for conventional drilling.
The RVDS is supplied to the rig as a complete system consisting of the downhole tool and an independent PC-based surface system. The downhole tool can be divided into three parts, each approximately 1.5 m long. It is connectable with standard DI22 8 1/4" threads with normal wrench flats to fit all types of raise bore machines. In order to monitor the self-steering drilling process, data signals are transmitted to the surface via positive mud pulses and are received decoded and visualized by a surface unit.
Compared with other tools available on the world market today, the RVDS tool has the following advantages:
- Can be handled by the raise boring machine without any modifications or moving of machine
- Same drilling parameters as normal raise boring (rpm, load,…)
- Drilling to final diameter directly (12 1/4" - 15")
- No extra operators or engineers necessary. Easy to understand
- Easy assembling and disassembling of tool
- Rental prices are fixed meter price