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