Source:Department of Earth Sciences, Laurentian University, Volume MSc, p.72 (2014)
Keywords:conductivity, cross borehole, electric dipole, electromagnetics, geophysics, modelling, radio imaging method, simulation, tomography
Information as to how the signal of the Radio Imaging Method (RIM) changes when the system parameters change or the rock properties change is not well documented. Having a better understanding of the impact of these changes would assist in the design of surveys and the interpretations of RIM data. To quantify the impacts, a modelling program was created by representing the transmitter as an electric dipole. It outputs the amplitude and phase of the electric field in a homogeneous whole space. The system parameters were varied to investigate their effects on the measured signal. It was found that increasing the conductivity or the magnetic permeability resulted in amplitude attenuation and sharper anomalies, while increasing the dielectric permittivity resulted in increased amplitude and broader anomalies. A case study was performed using data from Drury Township, near Sudbury, Ontario, Canada. The mostly homogeneous section of field data was fit with synthetic data whose conductivity values ranged in the 10-3 S/m magnitude. A better fit was found using a conductivity of 3*10-4 S/m, by increasing the relative dielectric permittivity from 1 to between 18 and 20. It was concluded that the program was effective at fitting homogeneous sections of field data, and was developed into RIM forward model software for easy use.