scholarly journals Electrical conductivity and pore-space topology of Merapi Lavas: Implications for the degassing of porphyritic andesite magmas

2001 ◽  
Vol 28 (22) ◽  
pp. 4283-4286 ◽  
Author(s):  
Jean-Luc Le Pennec ◽  
Daniel Hermitte ◽  
Isya Dana ◽  
Philippe Pezard ◽  
Christian Coulon ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Pore Space ◽  
Space Topology

scholarly journals Parameter Selection for the Evaluation of Compost Quality

Agronomy ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1567
Author(s):  
Haydee Peña ◽  
Heysa Mendoza ◽  
Fernando Diánez ◽  
Mila Santos
Keyword(s):  
Electrical Conductivity ◽  
Organic Matter ◽  
Pore Space ◽  
Linear Regression Analysis ◽  
Organic Matter Content ◽  
Principal Component ◽  
Primary Component ◽  
Matter Content ◽  
Germination Index ◽  
Soil Restoration

This work studies variables measured from the first phase of composting through the acquisition of the final product, with the goal of identifying those that are more strongly related to quality and are most useful for developing an index. The necessity to establish quality control procedures thus exists for the classification of raw materials in the same way as for the finished products. To accomplish this, three mixtures were prepared, with the goal of achieving a C/N ratio of 30 and a moisture content of 60%. The primary component of each mixture was: fruit processing waste (C1), sewage sludge from the food industry (C2), and the manufacturing waste of fried foods (C3). Temperatures were measured over 107 days, with the corresponding data fit to a logistical model where T °C ~ α / ((1 + exp (− (Time − β) / − γ))) + δ, with interaction compost * time being statistically significant (p < 0.001). This allowed for the temperatures, in keeping with health concerns, to be confirmed. Likewise, a linear regression analysis demonstrated the decomposition of organic matter at 0.82%/week. Statistically, the parameters, measured during the process, with the least variability were selected, which differed in the average contrasts: germination index (cucumber), electrical conductivity, and average moisture. A principal component analysis (PCA) and Spearman’s correlation analysis revealed the best Germination Index (GI) values for C1, due to lower electrical conductivity (EC) and bulk density (Bd) along with higher organic matter content (TOM). For its part, C2 induced a higher Relative emergence (RE) of the cucumber thanks to its higher content of total nitrogen (TN) and lower contribution of Cu, Zn and K. C3 showed a higher presence of salts, less favorable physical characteristics (>Bd and <TPS, total pore space) and higher content of Zn and Cu. Composting carried out with appropriate mixtures can offer high-quality products for use as fertiliser, in soil restoration, and as an alternative substrate to peat and virgin mountain soil.

Scaling of Transport Properties of Reservoir Material at Low Saturations of a Wetting Phase

1994 ◽  
Vol 367 ◽  
Author(s):  
Y. Carolina Araujo ◽  
Pedro G. Toledo ◽  
Hada Y. Gonzalez
Keyword(s):  
Electrical Conductivity ◽  
Porous Media ◽  
Transport Properties ◽  
Capillary Pressure ◽  
Power Law ◽  
Scaling Laws ◽  
Pore Space ◽  
Conductivity Data ◽  
Phase Saturation ◽  
Electrical Conductivity Data

AbstractTransport properties of natural porous media have been observed to obey scaling laws in the wetting phase saturation. Previous work relates power-law behavior at low wetting phase saturations, i.e., at high capillary pressures, to the thin-film physics of the wetting phase and the fractal character of the pore space of porous media. Here, we present recent combined porousplate capillary pressure and electrical conductivity data of Berea sandstone at low saturations that lend support to the scaling laws. Power law is interpreted in terms of the exponent m in the relation of surface forces and film thickness and the fractal dimension D of the interface between pore space and solid matrix. Simple determination of D from capillary pressure and m from electrical conductivity data can be used to rapidly determine wetting phase relative permeability and capillary dispersion coefficient at low wetting phase saturations.

Influence of Microgeometry on Membrane Potential of Shaly Sands

1990 ◽  
Vol 195 ◽  
Author(s):  
Pabitra N. Sen
Keyword(s):  
Electrical Conductivity ◽  
Membrane Potential ◽  
Pore Space ◽  
Geometrical Parameters ◽  
Formation Factor ◽  
Water Conductivity ◽  
Shaly Sand ◽  
Local Geology ◽  
Geometrical Factors

ABSTRACTThe microgeometry of the pore space influences the membrane potential Em. and theDC electrical conductivity σ of a shaly sand in a similar manner, independent of the details of the geometry: Em and σ being related via the conductivities of cations and σanions;σ=σcation + σ onion, and Em α σ cation/(σcation + σanion). This explicit relationship is used to investigate the role of the geometrical factors which influence both Em and σ in a related manner. The dependence of σ on the water conductivity σw can be well approximated with four geometrical parameters which can be obtained from the slopes and the interceptsof σ vs. σw curve at high and low salinities. We show that these geometrical factors appear in the expression for Em a well. These geometrical parameters (one of them is the formation factor) vary from rock to rock, and any trend in these parameters depend on the local geology.

The Influence of Activated Dispersed Additives on Electrical Conductivity of Anhydrite Compositions

2021 ◽  
Vol 321 ◽  
pp. 51-57
Author(s):  
Grigory Ivanovich Yakovlev ◽  
Ekaterina V. Begunova ◽  
Rostislav Drochytka ◽  
Jindřich Melichar ◽  
Igor Aleksandrovich Pudov ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Ir Spectrum ◽  
Electrical Resistance ◽  
Pore Space ◽  
Nitrate Solution ◽  
Microstructural Analysis ◽  
Calcium Nitrate ◽  
Absorption Lines ◽  
Structure And Properties ◽  
Crystalline Hydrates

The paper presents the results of studies of the structure and properties of a fluorohydrite binder modified by a chrysotile nanotubes dispersion in a medium of calcium nitrate solution. It is shown that addition of this modifier into the anhydrite composition leads to a 106-fold decrease in electrical resistance. Microstructural analysis of the fluorohydrite composition showed changes in the morphology of new formations with the creation of crystalline hydrates of increased density. The presence of elongated nanocrystals on the surface of the hardened matrix was noted. In addition, IR spectrum absorption lines, prove the presence of calcium nitrate in the pore space of the composition, which contributes to a significant decrease in the electrical resistance of the developed composite.

Simulated electrical conductivity response of clogging mechanisms for managed aquifer recharge

Geophysics ◽  
2014 ◽  
Vol 79 (2) ◽  
pp. D81-D89 ◽  
Author(s):  
A. Rowan Cockett ◽  
Adam Pidlisecky
Keyword(s):  
Electrical Conductivity ◽  
Specific Surface ◽  
Surface Area ◽  
Specific Surface Area ◽  
Film Growth ◽  
Volume Fraction ◽  
Pore Space ◽  
Managed Aquifer Recharge ◽  
Aquifer Recharge ◽  
Conductive Film

Motivated by the need for improved understanding and monitoring of clogging during managed aquifer recharge, we use numerical experiments to evaluate the effect of three different clogging mechanisms on electrical conductivity (EC), porosity, specific surface area, and electrical tortuosity of a simulated sediment pack. The clogging experiments are designed to simulate effect of clogging due to: (a) addition of finer grains, (b) addition of nonconductive films, and (c) addition of conductive films. The simulations involved starting with a random grain pack of 43% porosity, and subsequently reducing the porosity as would occur during clogging. For each of the experiments, we compute the EC response, specific surface area, and electrical tortuosity across the range of porosities. The differences in EC response between (a) and (b) is minor, however, the sediment parameters measuring pore-space configuration show very different responses (i.e., specific surface area and tortuosity), indicating EC is limited in its sensitivity to specific pore configurations. The results from simulations (a) and (b) are well described by Archie’s equation. For the conductive film experiments (c), we explore the effect of film growth for four different surface conductivities ranging from [Formula: see text] to [Formula: see text]. These conductivities correspond to a range of 5–35 times more conductive than the pore fluid conductivity. The bulk EC signal for each of the films results in a distinct manifestation in terms of measured bulk EC. We fit the EC response of the conductive film experiments with a model based on volume fraction occupied by the film; although the model fit the observed results, we required a unique set of fitting parameters for each Film conductivity.

Object-oriented approach for the pore-scale simulation of DC electrical conductivity of two-phase saturated porous media

Geophysics ◽  
2008 ◽  
Vol 73 (2) ◽  
pp. E67-E79 ◽  
Author(s):  
Emmanuel Toumelin ◽  
Carlos Torres-Verdín
Keyword(s):  
Thin Films ◽  
Electrical Conductivity ◽  
Porous Media ◽  
Random Walk ◽  
Water Saturation ◽  
Pore Space ◽  
Pore Network ◽  
Pore Scale ◽  
Exchange Cations ◽  
Wet Rocks

Archie’s empirical power laws are strictly valid only for homogeneous, water-wet (WW) rocks deprived of microporosity or substantial clay-exchange cations. When these conditions are not met, non-Archie electrical behavior arises whereby relationships among rock resistivity, porosity, and water saturation no longer exhibit power-law dependence. Currently, such an unreliable behavior of empirical laws can be quantified only through pore-scale modeling of electrical conductivity under specific sets of geometric assumptions and with substantial computation memory requirements. We introduce a new geometric concept to simulate direct-current electrical-conductivity phenomena in arbitrary rock models on the basis of 3D grain and pore objects that include explicit distributions of intragranular porosity, clay-exchange cations, nonwetting fluid blobs, thin films, and pendular rings. These objects are distributed in the pore space following simple heuristic principles of drainage/imbibition that honorcapillary-pressure curves. They provide a simple way to parameterize the 3D pore space and to calculate the electrical conductivity of porous media saturated with two immiscible fluid phases by way of diffusive random walks within the brine-filled pore space. Not only is the random-walk method memory efficient but it also allows the inclusion of clay/brine cation exchange surfaces otherwise not possible with conventional pore-network models. By comparing results stemming from random-walk, pore-network, and percolation simulations, we show the importance of grain surface roughness and thin film thickness, even in water-wet rocks where those factors usually are neglected. For the case of strongly oil-wet rocks, we show that thin films, snap-offs, and pore microgeometry have a primary impact on hysteresis-dominated rock resistivity during imbibition (increasing water saturation). Our simulation method agrees well overall with percolation simulation results and is advantageously unaffected by assumptions concerning site-percolation imbibition.

scholarly journals A novel saturation calculation model of fractured-vuggy carbonate reservoir via multiscale pore networks: a case study from Sichuan Basin, China

2021 ◽  
Vol 18 (1) ◽  
pp. 85-97
Author(s):  
Jianmeng Sun ◽  
Peng Chi ◽  
Zhigang Cheng ◽  
Lin Yang ◽  
Weichao Yan ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Sichuan Basin ◽  
Pore Space ◽  
Network Models ◽  
Pore Network ◽  
Carbonate Reservoir ◽  
Fluid Distribution ◽  
Scanning Method ◽  
Conductivity Mechanism ◽  
Simulation Results

Abstract Existing saturation models cannot effectively describe the specific fractured-vuggy carbonate reservoir in area A of the Sichuan Basin, southwestern China. This reservoir has got a wide pore size distribution, strong heterogeneity, high gas saturation and complex electrical conductivity mechanism. Hence, the present study attempted to establish a new saturation calculation equation for this carbonate reservoir based on the microscopic conductivity mechanism of the rock. Here, we first used the multiscale computed tomography (CT) scanning method to build multiscale digital rocks. Subsequently, we applied the maximum sphere algorithm to extract the pore space structure and constructed the multiscale pore network models. By using the cross-scale fusion method, four different pore configurations were determined. Then, the percolation theory was implemented to simulate the conductivity mechanism of the constructed pore network models. As a result, the fluid distribution characteristics and the resistivity variation trends of the different pore structures were obtained. The simulation results showed that the fracture system of the studied reservoir had a much greater effect than the vug system on the carbonate rock's electrical conductivity, and the conductivity was closely related to the fluid distribution. In addition, based on the simulation results, a new conductivity model was proposed that incorporates the coupling phenomenon of pores, vugs and fractures; and also a new saturation calculation equation for triple-porosity media was established. The observations indicated that the field application of the proposed equation had an acceptable performance with an error value of less than 2.56%. The results from the present study provide new insights into the evolution of electrical properties in triple-porosity carbonate systems.

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