3D induction: fact or fiction?

11/2/99


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Table of Contents

3D induction: fact or fiction?

Do we need to worry about 3D induction for mining scale problems?

3D induction in an isolated body of limited frequency range

Canadian generic EM ore body

2D response: centre site

2D inversion of “perfect” 2D data

2D cf. 3D response: centre site Mackie

3D comparison: centre site Mackie SYSEM (IE) EMIGMA (ILN)

2D cf. 3D response: centre site EMIGMA (ILN)

2D cf. 3D response: centre site EMIGMA “new”

2D cf. 3D response: centre site Mackie “new”

TM Rho_a comparison

TE Rho_a comparison

2D inversion of EMIGMA 3D data

Example: Okak Bay project

Large aeromag anomaly

Raw rho_a_av map @ 192 Hz

Raw rho_a_av map @ 192 Hz

Borehole intersections

Inversion of Line 6

Strike & distortion analysis

Distortion & anisotropy-corrected data

TE rho_a map @ 192 Hz

Real IV @ 500 Hz

1D inversion of site GAL004 data

2D inversion of Line 6

2D inversions of all lines

2D inversion of line Z

Pseudo-3D images from 2D inversions

Pseudo-3D model space: cutout

Pseudo-3D model space: projection

Pseudo-3D model space: body volume

Non-inductive response: Why?

Non-inductive response: Region of anomaly

Regional 3D currents - local charges?

EMIGMA modelling:

Conclusions - 1

Conclusions - 2

Conclusions - 3

Recommendations

Acknowledgements

Author: Alan G Jones

Email: ajones@cg.nrcan.gc.ca

Home Page: www.cg.nrcan.gc.ca/staff/jones

Other information:
Presentation given at 3D-EM II workshop in Salt Lake City on 27-29 October, 1999.