An overview of the spectral induced polarization method for near‐surface applications

Abstract

Over the last 15 years significant advancements in induced polarization (IP) research have taken place, particularly with respect to spectral IP (SIP), concerning the understanding of the mechanisms of the IP phenomenon, the conduction of accurate and broadband laboratory measurements, the modelling and inversion of IP data for imaging purposes, and the increasing application of the method in near-surface investigations. We here summarized the current state of the science of the SIP method for near-surface applications and describe which aspects still represent open issues and should be the focus of future research efforts.Significant progress has been made over the last decade in the understanding of the microscopic mechanisms of IP; however, integrated mechanistic models involving the different possible polarization processes at the grain/pore scale are still lacking. A prerequisite for the advances in the mechanistic understanding of IP was the development of improved laboratory instrumentation, which has led to a continuously growing database of SIP measurements on various soil and rock samples. We summarize the experience of numerous experimental studies by formulating key recommendations for reliable SIP laboratory measurements. To make use of the established theoretical and empirical relationships between SIP characteristics and target petrophysical properties at the field scale, sophisticated forward modelling and inversion algorithms are needed. Considerable progress has been made also in this field, in particular with the development of complex resistivity algorithms allowing the modelling and inversion of IP data in the frequency domain. The ultimate goal for the future are algorithms and codes for the integral inversion of 3-D, time-3 lapse and multi-frequency IP data, which defines a 5-D inversion problem involving the dimensions space (for imaging), time (for monitoring) and frequency (for spectroscopy). We also offer guidelines for reliable and accurate measurements of IP spectra, which are essential for improved understanding of IP mechanisms and their links to physical, chemical and biological properties of interest. We believe that the SIP method offers potential for subsurface structure and process characterization, in particular in hydrogeophysical and biogeophysical studies.

Quadrature conductivity: A quantitative indicator of bacterial abundance in porous media

“…In other words, it investigates the capacitance of porous media at low frequencies of the exciting electric field (typically between 1 mHz and 10 kHz). Recent reviews on this geophysical method, the associated mechanisms, and applications in environmental geosciences can be found in Kemna et al (2012) and Revil et al (2012b). The in-phase component of the complex conductivity describes the electromigration of the charge carriers in the material, whereas its quadrature component describes the polarization.…”

Modeling the evolution of complex conductivity during calcite precipitation on glass beads

“…electromigration of the charge carriers) and polarization (i.e. the reversible storage of electrical charges) of porous materials (Kemna et al 2012). Polarization of oxides and carbonates minerals such as calcite is related to the polarization of the electrical double layer (EDL) surrounding the particles under an external alternating current or electrical field (Chelidze & Gueguen 1999;Jougnot et al 2010;Revil & Florsch 2010).…”

In situ field measurements of the temporal evolution of low-frequency sea-ice dielectric properties in relation to temperature, salinity, and microstructure

“…The rise in ε at low frequencies has been examined in several studies of composite media (e.g., Buchanan et al, 2011;Kemna et al, 2012;Bücker and Hördt, 2013). In sea ice and other porous media, space charge polarization is labeled as the primary cause for this increase below frequencies of about 100 Hz.…”

“…Such features complicate pore geometry and will increase SA/V . Pore necks are a potential source of membrane polarization, in which reduced mobility of a specific type of ion within the fluid in a narrow pore result in a polarization effect (Kemna et al, 2012;Bücker and Hördt, 2013). SA/V ratio has the greatest loading for the second principal component responsible for 20 % of variance in apparent permittivity.…”