20 November 2024 | 10:00 AM (CST)
Induced polarization (IP) is a valuable geophysical tool used to predict key subsurface properties that control fluid flow and transport in sedimentary materials. Using an extensive dataset of 264 samples composed of sandstones, carbonates, and mudstones, this webinar will explore the properties controlling IP signatures. All samples are observed to be influenced by variations in electrochemical parameters (i.e., specific polarizability), with sandstone and carbonate samples showing a stronger relationship between IP parameters (imaginary conductivity and normalized chargeability) and volumetric magnetic susceptibility (κ) compared to IP parameters and pore geometric properties.
Additionally, unlike unconsolidated sediments, no significant relationship is found between IP parameters and surface area normalized to pore volume (S_por). The formation factor (F) exerts primary control on IP parameters in these samples. In the finer-grained mudstones, the modified Hagen-Poiseuille model, which links k to F and an effective pore radius (r), provides an excellent fit to the dataset with a near-constant pore radius, indicating that the effective porosity (1/F) is the controlling factor on k. Furthermore, a strong linear relationship is found between IP parameters and surface conductivity for sandstones, carbonates, and mudstones. The proportionality factor (l) describing the ratio between IP parameters and surface conductivity varies significantly across different rock types. Estimates of F for individual rock types (sandstone, carbonate, or mudstone) are improved when using l values specific to that rock type, although F estimates for carbonates and mudstones show high sensitivity to changes in l, which are controlled by variations in clay content.
Speaker Bio
Klaudio Peshtani
Klaudio Peshtani is a joint postdoctoral researcher at Rutgers University–Newark and the Pacific Northwest National Laboratory (PNNL). He earned his PhD in March 2024 and specializes in investigating the factors controlling Spectral Induced Polarization (SIP) in porous sediments and rocks. His current work at PNNL focuses on using SIP as a tool to monitor soil organic matter (SOM) complexation, with the aim of advancing SIP as a reliable technique for in-situ environmental monitoring.