Development of a core holder for consolidated and unconsolidated rocks to determine their complex electrical properties
Investigating complex electrical properties of natural rocks and soils by using spectral induced polarization (i.e. “low frequency impedance spectroscopy, typically from 1 mHz up to 100 kHz) is of high research interest for all pore space and boundary surface specific processes and properties between the matrix and the pore fluid. The deduction of hydraulic and pore space related structural properties, as well as the correlation of SIP-data with CAL and SCAL data is recently in the focus of research. In the past ten years, especially the development of new measurement equipment has greatly improved the quality of the results. Nevertheless, no uniform standards and technical requirements exist for adequate core holders for the determination of SIP related parameters. Furthermore, most of the core holders do not take different materials (unconsolidated, consolidated) or different core geometries (diameter, length, cross-section shape) into account. Within the department Petrophysics and Borehole Geophysics of the Leibniz Institute for Applied Geophysics (LIAG), a new and modular core holder for measuring complex electrical properties has been developed, in order to address the mentioned needs and functionalities. In addition, the core holder is characterized by a significantly reduced residual noise, so that also rock materials, which feature low frequency phase effects (such as Fontainebleau or Nivelsteiner Sandstone), can be investigated with high measurement accuracy and excellent reproducibility. The core holder is currently pending for patent and already commercially available for interested working groups.