The continuous wedging tool ‘CWT’ is a non-coring directional drilling system that is operated by the weight and the rotation of the drill rods. The drilling fluid doesn’t have a direct relation with the operation of the CWT and serves to clean and lubricate the drill bit and transport the cuttings to the surface. The deviations made with the CWT are short (2 to 3-meters long) and spaced out with about 6 to 15 meters of regular wireline coring in-between. The deviations created are the same size as the hole size, but careful reaming needs to be done before continuing with wireline drilling. The gain from one deviation is usually 2 degrees and the loss of core in the deviation is acceptable as it’s insignificant and always before any orebodies. In the rare cases where the CWT deviation enters the ore and the geological information is important, that section can be repeated and cored.
- Low cost
- No depth limitation.
- No additional mud pumps required or any other equipment.
- No trained drillers are needed.
- No steel left in the hole after deviations.
- No spare parts charges.
- Light equipment - the entire CWT equipment easily fits in the back of any pick-up truck
- No core during deviations.
- Survey of the deviation is possible only after the CWT is out of the hole and the core barrel is back at the bottom
- Unable to provide a continues curve.
- Length:2.5-2.7m (depends on tool design);
- CWT OD:72.00mm;
- Bit diameter:NQ (full face 75.00mm);
- Weight:45-55kg (depends on the design);
- Build up rate:0.2-1.0deg/m;
- Drill rig:Standard exploration drill rig;
- Drill rods:Standard N-size rods;
- Mud pump:The existing rig pump;
- Drill crew CWT experience:None required;
Technical and operational conditions
Core barrel pull out;
CWT run in hole;
Drilling with CWT(2 - 3m);
Pull out the CWT;
Go back down with the core barrel;
Ream, core drilling for 6m and survey;
Analyse the results;
Repeat steps if more steering is needed.
Systems and Procedures
On TrakTM is software developed by BG Drilling in order to execute complicated calculations in regard to directional drilling and Hole Path Control (HPC). We claim that it is the most sophisticated directional drilling software in the industry and one of the most important factors of proper and successful project execution. On TrakTM evaluates natural borehole trends, calculates what is required to reach a specific target, and optimizes the drilling plan. Besides the numerical section, there is a graphical expression of the drilling plan and multiple options.