by joe mihelcic, geophysicist clearview geophysics inc. ontario exploration & geoscience...

By Joe Mihelcic, Geophysicist

ClearView Geophysics Inc.

Ontario Exploration & Geoscience Symposium“New Ideas, Revisiting Past Discoveries”December 7, 2010

Any induced polarization survey that utilizes boreholes to: Inject currentor Measure potentials

Most common scenario is that favourable mineralization intersected in at least one borehole: Test if target is chargeable Quantify in or around borehole Determine Orientation/Direction/Extents Prioritize available geophysics and

drilling data

Many configurations and methods available: Mise-a-la-masse In-hole Pole-dipole and dipole-dipole Hole-to-hole Gradient Etc. etc.

Keep it simple Configure using basic physics Include external data Consider cost/risk vs. benefit/reward

E.g., tomographic mode for mineral exploration?

Favourable mineralization detected in a number of boreholes spread over wide area

Favoured theory suggests overall mineralizatoin plunges towards the northwest

Attempt BHIP to test this theory from borehole with good intersection 158.2 m -193.6 m

Run a simple dipole-dipole detection log to determine if intersected zone is chargeable:

Charge the target zone with Current Electrodes above and below the zone: C1 = 162 m (VG at 176 m) C2 = 225 m

Read potentials on surface Ensure lines at 90 degrees to BH

direction Tie-in to surface BH’s (bush crash)

Axis ‘A’ identified along chargeability trend

Axis ‘A’ identified along chargeability trend

Compare to available geophysics data

Compare to available geophysics data

Compare to available geophysics data

Focused post-processing of previously acquired surface pole-dipole geophysics data Inversion modeling Overlay drilling locations in 3D

- Not available on website download due to size

- Available upon request

Which boreholes drilled through zone?

Re-examine logs to find anomaly source

Recommend tighter drilling along source axis if favourable intersections already encountered

BHIP requires more customization than standard surface arrays

Inversion modeling useful in some cases, at end of process, especially for 3D visualization

A method to further prioritize surface IP results