Improvements in Acquisition hardware and processing methods have now shown Electrical Resistivity Imaging is a viable way to give detailed electrical images of structures like voids, geological structures, buried objects and similar. These can be converted into meaningful interpretations that can be used like a picture or template. It's a solution to use where reflective methods like Ground Radar or inductive methods like EM are difficult or impossible to use.
Survey Field operations Australia
State of the art
Direct current electrical surveying along the earth’s surface is a well-known geophysical exploration technique.
The method uses an artificial DC power source to create an electric field in the subsurface by injecting current into the ground between two metallic electrodes. By measuring and analysing the potential (voltage) response on the ground surface or underground (in boreholes or in a mine), one can obtain a resistivity distribution map of the subsurface. This map is then used with other information to help identify and delineate geological structures.
Field Crews working in Australia
Traditional DC electrical resistivity surveying uses various current – potential electrode arrangements depending on the prospecting aims and the surface situation. Modern DC resistivity techniques make use of recent developments in geophysical inversion theory. The technique relies on the faster computers now available for the inversion processing.
Example processed Image
Cross-hole DC electrical surveying is able to yield detailed information on the variation of electrical conductivity between two boreholes. In this mode, the current and potential electrodes are placed down hole in two horizontally separated boreholes. The electrodes are then moved over a range of depths to measure the electrical resistivity over many current paths. Specialised inversion programs then convert this data into an electrical resistivity tomogram.
Example Interpreted ERI Image (Coal Seams)
Schematic of field setup
Electrical resistivity imaging uses an automatic switching unit and multiple electrode array gathering high resolution data sets in short periods of time. Surveys can be designed to have high resolution at variable target depths. Induced Polarisation (IP) data can also be collected using the same equipment. Field techniques are non invasive, environmentally friendly and mobile. Data processing is conducted using
proprietary inverse modelling software.
We
use a variety of geophysical methods, Radar, EM, Electrical
Resistivity Imaging, Cross-hole surveys
Talk to SSI about your Geophysical
Imaging OR Cross-hole information ISSUE
