Numerical modelling and inversion of borehole induced polarization data

Javaheri Koupaei, Amir.H.(Amirhossein) (2012) Numerical modelling and inversion of borehole induced polarization data. Masters thesis, Memorial University of Newfoundland.

	[English] PDF (Migrated (PDF/A Conversion) from original format: (application/pdf)) - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. Download (37MB) [English] PDF - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. (Original Version)
	[English] Archive (ZIP) (Appendix B : 3D Forward Modelling Code for DC resistivity and IP data) - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. Download (87MB)

Abstract

The classical borehole Induced Polarization (IP) for mineral exploration is using a lateral probe where the two potential electrodes and one current electrode are deployed in one probe and used to measure the voltage in the drill-hole while the other current electrode is placed on the ground at infinity. Classical borehole IP has several limitations including an investigation radius that is restricted by borehole depth, depth of measurements limited by borehole depth, sensitivity to in-hole mineralization ,and data are not suited to 3D inversion. In the first part of this thesis, numerical modelling and inversion methods for the measurements of a novel IP borehole survey design have been investigated. The new survey design called, hole-to-hole lP, has been introduced by Abitibi Geophysics and aims to compensate the limitations of classical borehole IP especially in providing data that are suitable for 3D modeling and inversion. The geophysical modelling package "DCIP3D" provided by Geophysical Inversion Facility of the University of British Columbia has been used for forward modelling and inversion of hole-to-hole IP data. Different combinations of receivers and boreholes have been examined to obtain the economically optimum survey design including the minimum number of boreholes and receiver locations for a successful imaging of the chargeable ore body in a mineral exploration project. Also, a weighting function has been applied to improve the imaging of the mineral deposit located between boreholes. In the second part of the thesis, a 3D numerical modeling techniques based on integral equation methods for modelling of DC resistivity and IP data has been developed. The pivotal novelties in the code are, first, the application of unstructured meshes which is more flexible to complicated geometry with respect to the structured mesh. Second, the 3D code has been developed to allow both constant and linearly variable charge inside each cell and this enables us to simulate the charge accumulation over the boundary surface more precisely. Therefore, the developed code will enable numerical modelling to be done for more complicated ore bodies than was previously the case.

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