1. Core orientation in vertical holes

2. Vertical hole in Portugal
Ground investigation for mine shaft
1250m deep (planned)
5m radius
Drillcon drilling contractor
Devico
Directional core drilling
Core orientation

3. Borehole specifications
Core orientation required in project specifications
Devico offered the DeviCore system, but mainly as a ”steering” tool to keep track of borehole inclination. Core orientation would be possible if inclination was above -88.5°.

4. DeviCore system Continuous orientation Single point orientation
Scratchers marks the core during drilling
Single point orientation
The core is marked on surface after drilling

5. DeviCore 0° tool face aligned with master scratcher/mark
DeviCore principal
DeviCore 0° tool face aligned with master scratcher/mark

6. Drilling equipment Atlas Copco Corac N3/50 core barrel
3m inner tube with split tubes
50mm core

7. DeviCore in Corac
Difficult to accommodate the DeviCore in the split tubes
DeviCore takes up 1 meter of the inner tube
Solution: 1.5m extension behind the inner tube/split tubes and on the core barrel

8. Mark on the inner tube corresponds with DeviCore
Core orientation
Mark on the inner tube corresponds with DeviCore

9. Core orientation cont. Drill 3m as normal Reduce or remove water flow
Instrument reading before breaking the core

10. Mark the core at 0° tool face and pump the split tubes
Core orientation cont.
Mark the core at 0° tool face and pump the split tubes

11. Mark the core according to tool face reading (shows up)
Core orientation cont.
Mark the core according to tool face reading (shows up)

12. DeviCore results Core orientation has worked (surprisingly) well
Good results achieved even at inclinations down to -89.3°
Normal error 0°-10°
Maximum error about 30°-40°
All orientation work performed by the drillers

13. Understanding the orientation
Some issues getting the core loggers to understand the orientation
Making the orientation line from the reference mark
Vertical hole gives rapid changes in azimuth which moves the orientation line over the rock structures

14. Directional core drilling
High natural deviation
Soft and fractured rocks
Dogleg setting of 6!!
5 DeviDrill corrections
before 450m