Interfacial polarization of disseminated conductive minerals in absence of redox-active species — Part 1: Mechanistic model and validation

Geophysics ◽  
2016 ◽  
Vol 81 (2) ◽  
pp. E139-E157 ◽  
Author(s):  
S. Misra ◽  
C. Torres-Verdín ◽  
A. Revil ◽  
J. Rasmus ◽  
D. Homan
Keyword(s):  
Electrical Conductivity ◽  
Mechanistic Model ◽  
Interfacial Polarization ◽  
Active Species ◽  
Surface Conductance ◽  
Electrically Conductive ◽  
Mineral Inclusions ◽  
Redox Active ◽  
Polarization Phenomena ◽  
Complex Valued

Electrically conductive mineral inclusions are commonly present in organic-rich mudrock and source-rock formations such as veins, laminations, rods, grains, flakes, and beds. Laboratory and subsurface electromagnetic (EM) measurements performed on geomaterials containing electrically conductive inclusions generally exhibit frequency dispersion due to interfacial polarization phenomena at host-inclusion interfaces. In the absence of redox-active species, surfaces of electrically conductive mineral inclusions are impermeable to the transport of charge carriers, inhibit the exchange of charges and behave as perfectly polarized (PP) interfaces under the influence of an externally applied EM field. Interfacial polarization phenomena involving charge separation, migration, accumulation/depletion, and relaxation around PP interfaces is referred to as PP interfacial polarization; it influences the magnitude and direction of the electric field and charge carrier migration in the geomaterial. We have developed a mechanistic model to quantify the complex-valued electrical conductivity response of geomaterials containing electrically conductive mineral inclusions, such as pyrite and magnetite, uniformly distributed in a fluid-filled, porous matrix made of nonconductive grains possessing surface conductance, such as silica and clay grains. The model first uses a linear approximation of the Poisson-Nernst-Planck equations of dilute solution theory to determine the induced dipole moment of a single isolated conductive inclusion and that of a single isolated nonconductive grain surrounded by an electrolyte. A consistent effective-medium formulation was then implemented to determine the effective complex-valued electrical conductivity of the geomaterial. Model predictions were in good agreement with laboratory measurements of multifrequency complex-valued electrical conductivity, relaxation time, and chargeability of mixtures containing electrically conductive inclusions.

Interfacial polarization of disseminated conductive minerals in absence of redox-active species — Part 2: Effective electrical conductivity and dielectric permittivity

Geophysics ◽  
2016 ◽  
Vol 81 (2) ◽  
pp. E159-E176 ◽  
Author(s):  
S. Misra ◽  
C. Torres-Verdín ◽  
A. Revil ◽  
J. Rasmus ◽  
D. Homan
Keyword(s):  
Electrical Conductivity ◽  
Dielectric Permittivity ◽  
Electric Field ◽  
Relative Permittivity ◽  
Effective Conductivity ◽  
Interfacial Polarization ◽  
Surface Conductance ◽  
Frequency Dependent ◽  
Mineral Inclusions ◽  
Effective Electrical Conductivity

Hydrocarbon-bearing conventional formations, mudrock formations, and source-rock formations generally contain clays, pyrite, magnetite, graphitelike carbon, and/or other electrically conductive mineral inclusions. Under redox-inactive conditions, these inclusions give rise to perfectly polarized interfacial polarization (PPIP) when subjected to an external electric field. Effective electrical conductivity and dielectric permittivity of geomaterials containing such inclusions are frequency-dependent properties due to the electric-field-induced interfacial polarization and associated charge relaxation around host-inclusion interfaces. Existing resistivity interpretation techniques do not account for PPIP phenomena, and hence they can lead to inaccurate estimation of water saturation, total organic content, and conductivity of formation water based on subsurface galvanic resistivity, electromagnetic (EM) induction, and EM propagation measurements in the presence of conductive mineral inclusions. In the first paper of our two-part publication series, we derived a mechanistic electrochemical model, the PPIP model, and we validated a coupled model that integrates the PPIP model with a surface-conductance-assisted interfacial polarization (SCAIP) model to quantify the frequency-dependent electrical complex conductivity of geomaterials. We have used the PPIP-SCAIP model to evaluate the dependence of effective complex-valued conductivity of geologic mixtures on (1) frequency, (2) conductivity of the host medium, and (3) material, size, and the shape of inclusions. Notably, we have used the PPIP-SCAIP model to identify rock conditions that give rise to significant differences in effective conductivity and effective relative permittivity of conductive-inclusion-bearing mixtures from those of conductive-inclusion-free homogeneous media. For a mixture containing as low as a 5% volume fraction of disseminated conductive inclusions, the low-frequency effective conductivity of the mixture is in the range of [Formula: see text] to [Formula: see text] with respect to the host conductivity for frequencies between 100 Hz and 100 kHz. Further, the high-frequency effective relative permittivity of that mixture is in the range of [Formula: see text] to [Formula: see text] with respect to the host relative permittivity for frequencies between 100 kHz and 10 MHz.

scholarly journals Electrical conductivity in two mixed-valence liquids

2015 ◽  
Vol 17 (21) ◽  
pp. 14107-14114 ◽  
Author(s):  
Wenzhi Yao ◽  
Steven P. Kelley ◽  
Robin D. Rogers ◽  
Thomas P. Vaid
Keyword(s):  
Electrical Conductivity ◽  
Electron Transfer ◽  
Exchange Rate ◽  
Rate Constants ◽  
Room Temperature ◽  
Mixed Valence ◽  
Electrical Current ◽  
Active Species ◽  
Redox Active

Two mixed-valence room-temperature liquids are reported: BuFc–[BuFc+][NTf2−] (BuFc = n-butylferrocene) and TEMPO–[TEMPO+][NTf2−]. Both are conductors of DC electrical current, and their conductivity is modeled based on the electron-transfer self-exchange rate constants of their constituent redox-active species.

Dispersive and directional electrical conductivity and dielectric permittivity of conductive-mineral-bearing samples derived from multifrequency tensor electromagnetic induction measurements

Geophysics ◽  
2017 ◽  
Vol 82 (4) ◽  
pp. D211-D223 ◽  
Author(s):  
Siddharth Misra ◽  
Carlos Torres-Verdín ◽  
Dean Homan ◽  
John Rasmus
Keyword(s):  
Electrical Conductivity ◽  
Dielectric Permittivity ◽  
Glass Bead ◽  
Frequency Dispersion ◽  
Source Rocks ◽  
Relative Dielectric Permittivity ◽  
Electrically Conductive ◽  
Mineral Inclusions ◽  
Em Field ◽  
Graphite Inclusions

Organic-rich mudrocks, hydrocarbon-bearing conventional formations, and source rocks generally contain pyrite, rutile, graphite, graphitic precursors, and other electrically conductive minerals in the form of veins, laminations, flakes, and grains. Under redox-inactive subsurface conditions, when an external electromagnetic (EM) field is applied to geomaterials containing conductive mineral inclusions, ions in pore-filling brine and charge carriers (electrons and holes) in electrically conductive mineral inclusions migrate, accumulate/deplete, and diffuse around impermeable host-inclusion interfaces. These EM-field-induced phenomena are referred to as perfectly polarized interfacial polarization (PPIP) phenomena, and they alter the effective electrical conductivity [Formula: see text] and effective relative dielectric permittivity [Formula: see text] of geomaterials. In addition, the relaxation process associated with such polarization phenomena and the time required to fully develop and dissipate the EM-field-induced polarization gives rise to frequency dispersion of [Formula: see text] and [Formula: see text] of geomaterials containing conductive mineral inclusions. A laboratory-based EM apparatus, referred to as a whole-core EM induction tool, was used to measure the directional, multifrequency EM response of brine-saturated 4 in diameter (10.16 cm diameter), 2 ft long (0.61 m long), glass-bead packs containing uniformly distributed pyrite and graphite inclusions. We then implemented a semianalytic (SA) EM forward model, referred to as the SA model, to compute the [Formula: see text] and [Formula: see text] of these conductive-mineral-bearing glass-bead packs. The estimated [Formula: see text] and [Formula: see text] of conductive-mineral-bearing packs exhibit directional and frequency dispersive characteristics, which can be explained using the theory of PPIP phenomena. Relative variations in [Formula: see text] and [Formula: see text] due to frequency dispersion were as large as [Formula: see text] and [Formula: see text], respectively, between the values estimated at 20 and 260 kHz. Computed values of [Formula: see text] of conductive-mineral-bearing packs were unusually large in the range of 103–106, whereas the corresponding values of [Formula: see text] exhibited strong dependence on volume content, size, and metallic nature of conductive mineral inclusions, brine salinity, and frequency. Furthermore, packs containing uniformly distributed pyrite and graphite inclusions exhibited conductivity and permittivity anisotropy in the range of one to two.

Joint petrophysical inversion of multifrequency conductivity and permittivity logs derived from subsurface galvanic, induction, propagation, and dielectric dispersion measurements

Geophysics ◽  
2018 ◽  
Vol 83 (3) ◽  
pp. D97-D112 ◽  
Author(s):  
Yifu Han ◽  
Siddharth Misra
Keyword(s):  
Water Saturation ◽  
Mechanistic Model ◽  
Interfacial Polarization ◽  
Dielectric Dispersion ◽  
Surface Conductance ◽  
Inversion Algorithm ◽  
Shale Formations ◽  
Joint Interpretation ◽  
Shale Formation ◽  
Log Interpretation

Borehole-based subsurface electromagnetic (EM) measurements, namely, galvanic resistivity (laterolog), induction, propagation, and dielectric dispersion logs, are commonly used for water-saturation estimation in hydrocarbon-bearing formations. EM logs exhibit frequency dependence due to the interfacial polarization (IP) effects arising from clay-grain surfaces, conductive minerals, and charge blockage in pore throats. IP effects in shale formations adversely affect the log-derived water-saturation estimates, especially when there is low porosity, high salinity, the presence of pyrite disseminations, and high clay concentration. Conventional EM log-interpretation methods estimate water saturation in shale formations by separately interpreting the galvanic, induction, propagation, and dielectric dispersion logs using various empirical models or mixing laws. This approach leads to significant variations and uncertainties in petrophysical estimations. We have developed an inversion-based joint petrophysical interpretation of multifrequency effective electrical conductivity and dielectric permittivity logs derived from various combinations of the four aforementioned downhole EM logs acquired in clay- and pyrite-rich shale formations. The proposed joint-interpretation method uses a single mechanistic model that accounts for the IP effect arising from clay and conductive mineral grains, thereby generating physically consistent water-saturation estimates in shales. The proposed inversion-based interpretation also generates estimates of formation brine conductivity, surface conductance of clay, and average radius of clay and conductive mineral grains. The proposed method is applied to one field case and three synthetic geologic formations, with varying clay type, conductive mineral properties, and water saturation. Further, the sensitivity of inversion-derived estimates to the presence of various types of noise in the EM logs is investigated. The joint petrophysical inversion algorithm is applied to field broadband dispersion EM data acquired in an organic-rich shale formation. Water saturation, brine conductivity, surface conductance of clay, and radius of clay were consistently estimated in the shale formation using various combinations of available EM logs.

Polypyrrole/PU hybrid hydrogels: electrically conductive and fast self-healing for the potential application in body-monitor sensor

2021 ◽  
Author(s):  
Zhanyu Jia ◽  
Guangyao Li ◽  
Juan Wang ◽  
shouhua Su ◽  
Jie Wen ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Electrical Conductivity ◽  
Potential Application ◽  
Self Healing ◽  
Electrically Conductive ◽  
Sensor Application ◽  
Hybrid Hydrogels ◽  
Health Monitor

Conductivity, self-healing and moderate mechanical properties are necessary for multifunctional hydrogels which have great potential in health-monitor sensor application. However, the combination of electrical conductivity, self-healing and good mechanical properties...

scholarly journals Electrically Conductive Networks from Hybrids of Carbon Nanotubes and Graphene Created by Laser Radiation

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1875
Author(s):  
Alexander Yu. Gerasimenko ◽  
Artem V. Kuksin ◽  
Yury P. Shaman ◽  
Evgeny P. Kitsyuk ◽  
Yulia O. Fedorova ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Electrical Conductivity ◽  
Laser Irradiation ◽  
Flexible Electronics ◽  
Threshold Energy ◽  
Wavelength Region ◽  
Hybrid Nanostructures ◽  
Graphene Sheets ◽  
Electrically Conductive ◽  
Walled Carbon Nanotubes

A technology for the formation of electrically conductive nanostructures from single-walled carbon nanotubes (SWCNT), multi-walled carbon nanotubes (MWCNT), and their hybrids with reduced graphene oxide (rGO) on Si substrate has been developed. Under the action of single pulses of laser irradiation, nanowelding of SWCNT and MWCNT nanotubes with graphene sheets was obtained. Dependences of electromagnetic wave absorption by films of short and long nanotubes with subnanometer and nanometer diameters on wavelength are calculated. It was determined from dependences that absorption maxima of various types of nanotubes are in the wavelength region of about 266 nm. It was found that contact between nanotube and graphene was formed in time up to 400 fs. Formation of networks of SWCNT/MWCNT and their hybrids with rGO at threshold energy densities of 0.3/0.5 J/cm2 is shown. With an increase in energy density above the threshold value, formation of amorphous carbon nanoinclusions on the surface of nanotubes was demonstrated. For all films, except the MWCNT film, an increase in defectiveness after laser irradiation was obtained, which is associated with appearance of C–C bonds with neighboring nanotubes or graphene sheets. CNTs played the role of bridges connecting graphene sheets. Laser-synthesized hybrid nanostructures demonstrated the highest hardness compared to pure nanotubes. Maximum hardness (52.7 GPa) was obtained for MWCNT/rGO topology. Regularity of an increase in electrical conductivity of nanostructures after laser irradiation has been established for films made of all nanomaterials. Hybrid structures of nanotubes and graphene sheets have the highest electrical conductivity compared to networks of pure nanotubes. Maximum electrical conductivity was obtained for MWCNT/rGO hybrid structure (~22.6 kS/m). Networks of nanotubes and CNT/rGO hybrids can be used to form strong electrically conductive interconnections in nanoelectronics, as well as to create components for flexible electronics and bioelectronics, including intelligent wearable devices (IWDs).

scholarly journals Multi-material braids for multifunctional laminates: conductive through-thickness reinforcement

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Caroline O’Keeffe ◽  
Laura Rhian Pickard ◽  
Juan Cao ◽  
Giuliano Allegri ◽  
Ivana K. Partridge ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Carbon Fibre ◽  
Electromagnetic Interference ◽  
Design Tool ◽  
Electrically Conductive ◽  
Current Collection ◽  
Wide Range ◽  
Predictive Design ◽  
The Right ◽  
Metal Wires

AbstractConventional carbon fibre laminates are known to be moderately electrically conductive in-plane, but have a poor through-thickness conductivity. This poses a problem for functionality aspects that are of increasing importance to industry, such as sensing, current collection, inductive/resistive heating, electromagnetic interference (EMI) shielding, etc. This restriction is of course more pronounced for non-conductive composite reinforcements such as glass, organic or natural fibres. Among various solutions to boost through-thickness electrical conductivity, tufting with hybrid micro-braided metal-carbon fibre yarns is one of the most promising. As a well-characterised method of through thickness reinforcement, tufting is easily implementable in a manufacturing environment. The hybridisation of materials in the braid promotes the resilience and integrity of yarns, while integrating metal wires opens up a wide range of multifunctional applications. Many configurations can be produced by varying braid patterns and the constituting yarns/wires. A predictive design tool is therefore necessary to select the right material configuration for the desired functional and structural performance. This paper suggests a fast and robust method for generating finite-element models of the braids, validates the prediction of micro-architecture and electrical conductivity, and demonstrates successful manufacturing of composites enhanced with braided tufts.

Investigate of Electrical Conductivity of Shape-Memory Polymer Filled with Carbon Black

2008 ◽  
Vol 47-50 ◽  
pp. 714-717 ◽  
Author(s):  
Xin Lan ◽  
Jin Song Leng ◽  
Yan Ju Liu ◽  
Shan Yi Du
Keyword(s):  
Electrical Conductivity ◽  
Carbon Black ◽  
Shape Memory ◽  
Shape Recovery ◽  
Volume Fraction ◽  
Shape Memory Polymer ◽  
Recovery Process ◽  
Thermomechanical Properties ◽  
Electrically Conductive ◽  
New System

A new system of thermoset styrene-based shape-memory polymer (SMP) filled with carbon black (CB) is investigated. To realize the electroactive stimuli of SMP, the electrical conductivity of SMP filled with various amounts of CB is characterized. The percolation threshold of electrically conductive SMP filled with CB is about 3% (volume fraction of CB), which is much lower than many other electrically conductive polymers. When applying a voltage of 30V, the shape recovery process of SMP/CB(10 vol%) can be realized in about 100s. In addition, the thermomechanical properties are also characterized by differential scanning calorimetery (DSC).

Heterogeneous Preparation of Cellulose/Ag/Polyaniline Conductive Composite and its Electrical Property

2012 ◽  
Vol 182-183 ◽  
pp. 254-258
Author(s):  
Zhong Li Zhao ◽  
Zun Li Mo ◽  
Zhong Yu Chen
Keyword(s):  
Electrical Conductivity ◽  
Electrical Property ◽  
Conductive Network ◽  
High Electrical Conductivity ◽  
Electrically Conductive ◽  
Conductive Composite

Cellulose/Ag/polyaniline conductive composite with rather excellent electrical conductivity was heterogeneously synthesized in this paper. The UV-Vis analysis indicated that homogeneous nanoAg particles deposited on the surface of cellulose in the form of globe particles. They offered some electrons to polyaniline chains. This behavior resulted to the facts that more polyaniline embedded on cellulose and an integrated electrically conductive network formed. Consequently, the high electrical conductivity of the composite was observed. The value was 3.48 S/cm, which was higher two magnitudes than the electrical conductivity of cellulose/polyaniline composite (2.15×10-2S/cm), and even was higher than the electrical conductivity of pure polyaniline (0.142 S/cm). This paper provided a facile method for the preparation of cellulose/Ag/ polyaniline composite with favorable electrical conductivity.

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