Revisiting the Relationship Between Induced Polarization and Surface Conductivity: Ratios From Laboratory to Field

Journal Article · 04 April 2025 · Journal of Geophysical Research. Solid Earth

DOI: https://doi.org/10.1029/2024JB030406 · OSTI ID:2549472

Qi, Youzheng  ^[1]; Wu, Yuxin  ^[1]

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1. Earth and Environmental Sciences Area Lawrence Berkeley National Laboratory Berkeley CA USA

Abstract Among the subsurface geophysical methods used in the critical zone investigations, induced polarization (IP) shows great vitality thanks to its unique ability to assess porosity via bulk conduction and estimate permeability through surface conduction and/or polarization. However, such an advantageous separation between bulk and surface is mostly implemented by multi‐salinity experiments in the laboratory, which is incredibly difficult to realize in the field. One promising approach to address such an obstinate issue is to gauge the surface conductivity ( σ _s ) from the quadrature conductivity ( σ ″) or normalized chargeability ( M _n ) with the ratios between ( l  =  σ ″/ σ _s , l _mn  =  M _n / σ _s ). While these ratios are known not to be universal, the underlying principles are not fully understood and relevant theoretical studies are rare, which makes quantitative IP applications difficult. Here we scrutinize the conduction and polarization mechanisms of geomaterials and pinpoint that the two ratios are inherently functions of salinities and frequencies rather than only determined by the properties of the electrical double layer (EDL), hence representative samples from the investigated field must be calibrated in the laboratory and a characteristic frequency should be chosen for their usage. Besides the macro‐scale ratios l and l _mn , we define two micro‐scale ratios χ and χ _mn directly from the EDL, such that the new ratios exclude the effect of salinity and frequency and offer the opportunity to characterize and monitor changes of the EDL. Our study demonstrates that the existing macro‐scale ratios converge toward the values of novel micro‐scale ratios at high water salinity.

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: US Department of Energy; USDOE; USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23), Climate and Environmental Sciences Division (SC-23.1 )
• Grant/Contract Number: AC02-05CH11231
• OSTI ID: 2549472
• Journal Information: Journal of Geophysical Research. Solid Earth, Journal Name: Journal of Geophysical Research. Solid Earth Journal Issue: 4 Vol. 130; ISSN 2169-9313
• Publisher: American Geophysical Union (AGU)Copyright Statement
• Country of Publication: United States
• Language: English