Electrical resistivity tomography for petrophysical investigation

Determination of physical parameters of rock samples is essential to characterize their composition and structure. One of these parameters is electrical resistivity. Depending on porosity, resistivity of the pore fluid, saturation degree and matrix properties (esp. ore and graphite content, clay content), it thus yields information about these quantities. There are different methods for its determination as integral value over the sample (TELFORD et al. 1990 a.o.). RAUEN & SOFFEL (1995) have developed a method for the determination of transversal anisotropy. But it is not possible to estimate the spatial resistivity distribution within the core by these methods. Therefore we applied the principle of tomography. With this method we are able to detect and quantify anomalies due to fractures, cristallization of mobilisates, or spatial variations of the the pore fluid.