A more recent development with Electrical
Resistivity Imaging is the capability to do cross-hole surveys. This
are run using a standard surface system but with the addition of
specialist downhole cables.
The usual depth limits are between 150 to 300m for
most applications. In certain cases with specific electrode setups,
greater depths are possible
The surveys can be run Borehole to Borehole and surface
to Borehole. Surface array data can be combined with cross-hole data
to improve the image result.
Crosshole data , Mineral survey
Comparison
between the results from surface resistivity and crosshole
resistivity tomography.
Crosshole data Lateritic Iron Ore survey
Clearly the tomography shows a
greater level of detail. However, it would take several crosshole
panels to covers the same area as a full surface resistivity image.
