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 Scratchers marks the core during drilling Single point orientation The core is marked on surface after drilling

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

11. 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