The electrical conductivity and surface conduction of consolidated rock cores

Alkafeef, Saad F.; Alajmi, Abdullah F.

doi:10.1016/j.jcis.2007.02.004

Cited by 20 publications

(10 citation statements)

References 22 publications

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“…However, an exact quantitative analysis has not been done till now on the effect of the Stern layer conductivity on the streaming potential and on the electrokinetic coupling coefficient. Alkafeef and Alajmi [2007] measured the surface conductivity and the zeta potential for consolidated rock cores. They showed that the total surface conductivity is not ignorable at low salinity, but did not separate the contribution of the Stern layer to surface conductivity from that of the diffuse layer.…”

Section: Mathematical Formulationmentioning

confidence: 99%

“…The Pride's equations are valid if one uses experimentally obtained coefficients. In the earthquake wave frequency (which is less than several hertz) band, the conductivity and the coupling coefficient do not change with frequency and can be measured by experiments as done by Pengra et al [1999] and Alkafeef and Alajmi [2007]. In our modeling example, we use Pride's expressions for low‐frequency conductivity and coupling coefficient.…”

Section: Mathematical Formulationmentioning

confidence: 99%

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Electromagnetic field generated by a finite fault due to electrokinetic effect

Hu¹,

Gao²

2011

J. Geophys. Res.

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[1] This work investigates surface electromagnetic wavefields generated by a finite fault due to electrokinetic effect with Pride's theory as the governing equations. A finite fault is discretized into a series of small subfaults, each of which is taken as a point source with different initiation time. The wavefields generated by the whole fault are then synthesized by stacking those generated by all the subfaults. Numerical simulations of a vertical strike-slip fault with a constant rupturing velocity are then conducted on the basis of the derived formalism. Simulation results show that the rupturing fault generates observable permanent ground motions and electromagnetic field disturbances. Two types of electric field characters are observed in simulations: the coseismic oscillatory variation and the postseismic decaying variation. When the fault rupturing stops and the seismic waves pass far away, the magnetic field vanishes while the electric field remains, decaying slowly and lasting for hundreds of seconds. Adjacent to the free surface the vertical electric field is about 100 times larger than the horizontal one. When the receiving depth increases, the amplitudes of the horizontal electric fields in both the oscillatory and decaying components increase while those of the vertical electric fields decrease. It is also shown that there is no horizontal electric field remnant right at the free surface after the seismic perturbations decay away. The near-fault electric fields simulated in this paper hold similar features to some field observations in literature.Citation: Hu, H., and Y. Gao (2011), Electromagnetic field generated by a finite fault due to electrokinetic effect, J. Geophys.

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Section: Mathematical Formulationmentioning

confidence: 99%

Section: Mathematical Formulationmentioning

confidence: 99%

Electromagnetic field generated by a finite fault due to electrokinetic effect

Hu¹,

Gao²

2011

J. Geophys. Res.

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“…Pozzi 1995a, b, 1997;Alkafeef and Alajmi 2007;Vinogradov et al 2010). Glover et al (2006) collated a database of C sp and ζ determinations as a function of salinity, which is reproduced in Fig.…”

Section: Introductionmentioning

confidence: 99%

“…(Sprunt et al 1994;Pozzi 1995a, 1997;Li et al 1995;Jiang et al 1998;Pengra et al 1999); [2] sandstone with NaCl as a function of permeability/microstructure (pH5) (Jouniaux and Pozzi 1995b); [3] St. Bees, Stainton, and Fontainebleau sandstones with NaCl (Jaafar et al 2009;Vinogradov et al 2010); [4] sandstone with KCl (Alkafeef and Alajmi 2007); [5] sand with NaCl (Guichet et al 2003;Block and Harris 2006);[6] granite with NaCl (Morgan et al (1989)); [7] glass with NaCl (Pengra et al 1999;Block and Harris 2006);[8] zeolitized tuffs with NaCl (Revil et al 2002);[9] basalt with NaCl (Revil et al 2003 (Tardif et al 2011;Glover et al 2012a). b [1] Quartz with NaCl (Pride and Morgan (1991)); [2] silica with NaCl (Gaudin and Fuerstenau 1955;Li and Bruyn 1966;Kirby and Hasselbrink 2004);[3] glass beads with NaCl (Bolève et al 2007);[4] St.…”

Section: Introductionmentioning

confidence: 99%

“…[11] mica with NaCl (Will and Nover 1986);[12] sandstone with NaCl (Alkafeef and Alajmi 2007) These high-quality measurements would then allow us answer the questions posed above as well as to provide high-quality experimental data against which the theoretical model of Glover and Déry (2010) and Glover et al (2012b) could be rigorously tested. This paper addresses the questions posed above and reserves the modelling to a forthcoming paper.…”

Section: Introductionmentioning

confidence: 99%

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Measurements of the Relationship Between Microstructure, pH, and the Streaming and Zeta Potentials of Sandstones

Walker

Glover

2017

Transp Porous Med

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A large number (1253) of high-quality streaming potential coefficient (C sp ) measurements have been carried out on Berea, Boise, Fontainebleau, and Lochaline sandstones (the latter two including both detrital and authigenic overgrowth forms), as a function of pore fluid salinity (C f ) and rock microstructure. All samples were saturated with fully equilibrated aqueous solutions of NaCl (10 −5 and 4.5 mol/dm 3 ) upon which accurate measurements of their electrical conductivity and pH were taken. These C sp measurements represent about a fivefold increase in streaming potential data available in the literature, are consistent with the pre-existing 266 measurements, and have lower experimental uncertainties. The C sp measurements follow a pH-sensitive power law behaviour with respect to C f at medium salinities (C sp = − 1.44 × 10 −9 C − 1.127 f , units: V/Pa and mol/dm 3 ) and show the effect of rock microstructure on the low salinity C sp clearly, producing a smaller decrease in C sp per decade reduction in C f for samples with (i) lower porosity, (ii) larger cementation exponents, (iii) smaller grain sizes (and hence pore and pore throat sizes), and (iv) larger surface conduction. The C sp measurements include 313 made at C f > 1 mol/dm 3 , which confirm the limiting high salinity C sp behaviour noted by Vinogradov et al., which has been ascribed to the attainment of maximum charge density in the electrical double layer occurring when the Debye length approximates to the size of the hydrated metal ion. The zeta potential (ζ ) was calculated from each C sp measurement. It was found that ζ is highly sensitive to pH but not sensitive to rock microstructure. It exhibits a pH-dependent logarithmic behaviour with respect to C f at low to medium salinities (ζ = 0.01133 log 10 (C f ) + 0.003505, units: V and mol/dm 3 ) and a limiting zeta potential (zeta potential offset) at high salinities of ζ o = − 17.36 ± 5.11 mV in the pH range 6-8, which is also pH dependent. The sensitivity of both C sp and ζ to pH and of C sp to rock microstructure indicates that C sp and ζ measurements can only be interpreted together with accurate and equilibrated measurements of pore fluid conductivity and pH and supporting microstructural and surface conduction measurements for each sample.

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Surface conductivity in electrokinetic systems with porous and charged interfaces: Analytical approximations and numerical results

Barbati

Kirby

2016

Electrophoresis

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We derive an approximate analytical representation of the conductivity for a 1D system with porous and charged layers grafted onto parallel plates. Our theory improves on prior work by developing approximate analytical expressions applicable over an arbitrary range of potentials, both large and small as compared to the thermal voltage (RTF). Further, we describe these results in a framework of simplifying nondimensional parameters, indicating the relative dominance of various physicochemical processes. We demonstrate the efficacy of our approximate expression with comparisons to numerical representations of the exact analytical conductivity. Finally, we utilize this conductivity expression, in concert with other components of the electrokinetic coupling matrix, to describe the streaming potential and electroviscous effect in systems with porous and charged layers.

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The electrical conductivity and surface conduction of consolidated rock cores

Cited by 20 publications

References 22 publications

Electromagnetic field generated by a finite fault due to electrokinetic effect

Electromagnetic field generated by a finite fault due to electrokinetic effect

Measurements of the Relationship Between Microstructure, pH, and the Streaming and Zeta Potentials of Sandstones

Surface conductivity in electrokinetic systems with porous and charged interfaces: Analytical approximations and numerical results

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