Quantitative Comparison of 3D Pore Space Properties With Magnetic Pore Fabrics—Testing the Ability of Magnetic Methods to Predict Pore Fabrics in Rocks

Abstract

The fabric of connected pores, that is, their shape, orientation, and connectivity, largely controls rock properties such as permeability. An accurate 3D description of pore fabrics has therefore many applications, including geothermal energy usage (

Physical and Chemical Stability of Nanoparticles in Ferrofluid Before and After Impregnation: Implications for Magnetic Pore Fabric Studies

“…Pore fabrics and the resulting permeability anisotropy play a crucial role in aquifer and reservoir characterization, production modeling, and the prediction of preferred flow paths (Ayan et al., 1994; Bear, 2013; Bear et al., 1987; Beard & Weyl, 1973; Huang et al., 2017; Ijeje et al., 2019; Panja et al., 2021; Rasolofosaon & Zinszner, 2002; Sinan et al., 2020; Storesletten, 1998; Wang et al., 2019; Willems et al., 2017). Common methods used for characterization include (a) determination of the permeability tensor, which in theory requires six independent directional permeability measurements (Rice et al., 1970), but is often approximated with two or three measurements within and normal to the macroscopically visible bedding or foliation (Armitage et al., 2011; Ayan et al., 1994; Dürrast & Siegesmund, 1999; Rice et al., 1970); and (b) visualization of numerous pores through optical, scanning and transmission electron microscopy or X‐ray computed tomography and their representation by, for example, orientation density functions of longest and shortest axes, ratios of axes lengths, and pore shapes (Baldwin et al., 1996; Keller & Holzer, 2018; Ketcham & Carlson, 2001; Ketcham & Iturrino, 2005; Landis & Keane, 2010; Timur et al., 1971; Zhou et al., 2022). For the first method, several cores or cubes are typically measured, and heterogeneities between samples can affect the estimate of anisotropy (Adams et al., 2013).…”

“…Apparent differences between published empirical relationships are largely explained by the different susceptibilities of the ferrofluids used, and by early studies neglecting distribution anisotropy (Biedermann, 2019, 2020). Ferrofluids that are commonly used in MPF studies include oil‐based EMG901, EMG905 and EMG909 (from highest to lowest susceptibility), and water‐based EMG705 (most common), EMG304, EMG507 and EMG509 (Almqvist et al., 2011; Benson et al., 2003; Biedermann & Parés, 2022; Biedermann et al., 2021; Hrouda et al., 2000; Humbert et al., 2012; Jones et al., 2006; Parés et al., 2016; Pfleiderer & Halls, 1990, 1993, 1994; Pfleiderer & Kissel, 1994; Pugnetti et al., 2022, 2023; Robion et al., 2014; Zhou et al., 2022). Initially, it was believed that oil‐based ferrofluids were more effective in impregnating rock, which was likely a misinterpretation related to differences between the effective susceptibility under standard measurement conditions (1 kHz) and the initial susceptibility listed in the fluids' technical specifications (Biedermann et al., 2021; Robion et al., 2014).…”