Numerical estimation of electrical conductivity in saturated porous media with a 2-D lattice gas

Geophysics ◽  
2000 ◽  
Vol 65 (3) ◽  
pp. 766-772 ◽  
Author(s):  
Michel Küntz ◽  
Jean Claude Mareschal ◽  
Paul Lavallée
Keyword(s):  
Electrical Conductivity ◽  
Porous Media ◽  
Power Law ◽  
Lattice Gas ◽  
Effective Conductivity ◽  
Pore Space ◽  
Solid Matrix ◽  
Conductivity Ratio ◽  
Saturated Porous Media ◽  
Formation Factor

A 2-D lattice gas is used to calculate the effective electrical conductivity of saturated porous media as a function of porosity and conductivity ratio [Formula: see text] between the pore‐filling fluid and the solid matrix for various microscopic structures of the pore space. The way the solid phase is introduced allows the porosity ϕ to take any value between 0 and 1 and the geometry of the pore structure to be as complex as desired. The results are presented in terms of the formation factor [Formula: see text], with [Formula: see text] the effective conductivity of the saturated rock and [Formula: see text] the conductivity of the fluid. It is shown that the formation factor F as a function of the porosity ϕ follows a power law [Formula: see text], equivalent to the empirical Archie’s law. The exponent m varies with the microgeometry of the pore space and could therefore reflect the microstructure at the macroscopic scale. The prefactor a of the power law, however, is close to 1 regardless of the microstructure. For a given microgeometry of the pore space, the variation of the residual electrical conductivity of the solid matrix induced by a finite conductivity ratio [Formula: see text] does not significantly influence the variation of the effective conductivity of the fluid‐solid binary mixture unless the porosity is low.

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.

scholarly journals A physically based model for the electrical conductivity of water-saturated porous media

2019 ◽  
Vol 219 (2) ◽  
pp. 866-876 ◽  
Author(s):  
Luong Duy Thanh ◽  
Damien Jougnot ◽  
Phan Van Do ◽  
Nguyen Van Nghia A
Keyword(s):  
Electrical Conductivity ◽  
Porous Media ◽  
Published Data ◽  
Saturated Porous Media ◽  
Formation Factor ◽  
Physically Based Model ◽  
Microstructural Parameters ◽  
Physically Based ◽  
Pore Liquid ◽  
Water Saturated

SUMMARY Electrical conductivity is one of the most commonly used geophysical method for reservoir and environmental studies. Its main interest lies in its sensitivity to key properties of storage and transport in porous media. Its quantitative use therefore depends on the efficiency of the petrophysical relationship to link them. In this work, we develop a new physically based model for estimating electrical conductivity of saturated porous media. The model is derived assuming that the porous media is represented by a bundle of tortuous capillary tubes with a fractal pore-size distribution. The model is expressed in terms of the porosity, electrical conductivity of the pore liquid and the microstructural parameters of porous media. It takes into account the interface properties between minerals and pore water by introducing a surface conductivity. Expressions for the formation factor and hydraulic tortuosity are also obtained from the model derivation. The model is then successfully compared with published data and performs better than previous models. The proposed approach also permits to relate the electrical conductivity to other transport properties such as the hydraulic conductivity.

Electrical conductivity modeling in fractal non-saturated porous media

2018 ◽  
Author(s):  
Wei Wei ◽  
Jianchao Cai ◽  
Yuxuan Xia ◽  
Xiangyun Hu ◽  
Qi Han
Keyword(s):  
Electrical Conductivity ◽  
Porous Media ◽  
Saturated Porous Media ◽  
Conductivity Modeling

scholarly journals Experimental study on retardation of a heavy NAPL vapor in partially saturated porous media

2017 ◽  
Vol 21 (3) ◽  
pp. 1381-1396 ◽  
Author(s):  
Simon Matthias Kleinknecht ◽  
Holger Class ◽  
Jürgen Braun
Keyword(s):  
Porous Media ◽  
Aqueous Phase ◽  
Unsaturated Zone ◽  
Large Scale ◽  
Water Saturation ◽  
Solid Matrix ◽  
Saturated Porous Media ◽  
Gaseous State ◽  
Partially Saturated ◽  
Partially Saturated Porous Media

Abstract. Non-aqueous-phase liquid (NAPL) contaminants introduced into the unsaturated zone spread as a liquid phase; however, they can also vaporize and migrate in a gaseous state. Vapor plumes migrate easily and thus pose a potential threat to underlying aquifers. Large-scale column experiments were performed to quantify partitioning processes responsible for the retardation of carbon disulfide (CS2) vapor in partially saturated porous media. The results were compared with a theoretical approach taking into account the partitioning into the aqueous phase as well as adsorption to the solid matrix and to the air–water interface. The experiments were conducted in large, vertical columns (i.d. of 0.109 m) of 2 m length packed with different porous media. A slug of CS2 vapor and the conservative tracer argon was injected at the bottom of the column followed by a nitrogen chase. Different seepage velocities were applied to characterize the transport and to evaluate their impact on retardation. Concentrations of CS2 and argon were measured at the top outlet of the column using two gas chromatographs. The temporal-moment analysis for step input was employed to evaluate concentration breakthrough curves and to quantify dispersion and retardation. The experiments conducted showed a pronounced retardation of CS2 in moist porous media which increased with water saturation. The comparison with an analytical solution helped to identify the relative contributions of partitioning processes to retardation. Thus, the experiments demonstrated that migrating CS2 vapor is retarded as a result of partitioning processes. Moreover, CS2 dissolved in the bulk water is amenable to biodegradation. The first evidence of CS2 decay by biodegradation was found in the experiments. The findings contribute to the understanding of vapor-plume transport in the unsaturated zone and provide valuable experimental data for the transfer to field-like conditions.

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.

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