Hydraulic Conductivity of Porous Media at Low Water Content

Toledo, Pedro G.; Novy, Robert A.; Davis, H. T.; Scriven, L. E.

doi:10.2136/sssaj1990.03615995005400030007x

Cited by 129 publications

(72 citation statements)

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“…In addition, adsorptive forces between water and matrix lead to the formation of a thin water film at the rock-air interface. Such water films with a thickness typically below 20 nm (e.g., Toledo et al, 1990;Tokunaga and Wan, 1997) exhibit very short NMR relaxation times. Although water films to some extent may influence transport properties and water distribution of a partially saturated porous system (Tuller and Or, 2001), the contribution of the film volume to NMR amplitudes is very small with respect to the NMR signal amplitudes arising from the water trapped in the menisci; i.e., V film V meniscus .…”

Section: Water Distribution During Drainage and Imbibition In A Partimentioning

confidence: 99%

Understanding NMR relaxometry of partially water-saturated rocks

Mohnke

Jorand

Nordlund

2015

Hydrol. Earth Syst. Sci.

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Abstract. Nuclear magnetic resonance (NMR) relaxometry measurements are commonly used to characterize the storage and transport properties of water-saturated rocks. Estimations of these properties are based on the direct link of the initial NMR signal amplitude to porosity (water content) and of the NMR relaxation time to pore size. Herein, pore shapes are usually assumed to be spherical or cylindrical. However, the NMR response at partial water saturation for natural sediments and rocks may differ strongly from the responses calculated for spherical or cylindrical pores, because these pore shapes do not account for water menisci remaining in the corners of desaturated angular pores. Therefore, we consider a bundle of pores with triangular cross sections. We introduce analytical solutions of the NMR equations at partial saturation of these pores, which account for water menisci of desaturated pores. After developing equations that describe the water distribution inside the pores, we calculate the NMR response at partial saturation for imbibition and drainage based on the deduced water distributions.For this pore model, the NMR amplitudes and NMR relaxation times at partial water saturation strongly depend on pore shape, i.e., arising from the capillary pressure and pore shape-dependent water distribution in desaturated pores with triangular cross sections. Even so, the NMR relaxation time at full saturation only depends on the surface-to-volume ratio of the pore. Moreover, we show the qualitative agreement of the saturation-dependent relaxation-time distributions of our model with those observed for rocks and soils.

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Section: Water Distribution During Drainage and Imbibition In A Partimentioning

confidence: 99%

Understanding NMR relaxometry of partially water-saturated rocks

Mohnke

Jorand

Nordlund

2015

Hydrol. Earth Syst. Sci.

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“…This was attributed to the impact of the distribution of smaller pores, and this topic shall be recalled within the present paper, as well. It is well known that at high water contents the WRC is governed by the distribution of larger pores, while at the low water contents the WRC is determined by the thin water film on the solid particles [11] [14] [15]. This naturally calls for a two-fold fractal interpretation of the retention process.…”

Section: The Two Regimes Fractal Modelmentioning

confidence: 99%

“…In the past years, an important boost came from the fractal geometry [6]- [8] which was used to characterize the hydraulic conductivity by means of the fractal properties of pore spaces ([9] [10]). This has permitted relating the fractal dimension at low water content values to the physics of thin water films [11] either by combining Kock's curve to the flow (Poiseuille) equation [12], or by dealing with the fractal dimension of the porosity and a diffusion-type (Millington and Quirk) equation [13]. An exhaustive review of all these models can be found in ( [14] [15] and references therein).…”

Section: Introductionmentioning

confidence: 99%

Two Fractal Regimes of the Soil Hydraulic Properties

Bartolo¹,

Fallico²,

Severino³

et al. 2014

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A fractal analysis of the soil retention and hydraulic conductivity curves is presented. The retention process is modeled by a two fractal regimes: one pertaining to high water content values, and another accounting for the low water content data. This significantly improves the physical insight of the retention process as compared with the case of one-fractal models. The fractal dimensions characterizing the two regimes are estimated by fitting the retention curve model upon real data, and subsequently they are used to determine the hydraulic conductivity which for the retention curve models of Mualem and Burdine, is obtained in closed form. The reliability of the model is tested against independent conductivity data collected in a field-scale campaign.

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“…Theoretical results for the dependence of the relative permeability of the wetting phase under conditions of film flow were obtained by de Gennes, 6 Novy, 7 and Toledo. 8 In the thick-film flow regime, de Gennes' theory predicts an exponent of the form (see Toledo et al 8 ). For values of D on the order of 2.3 to 2.6 and m‫ס‬ 1 ⁄2, one obtains estimates for b in the range 8.4 to 16.8.…”

Section: Introductionmentioning

confidence: 99%

Time Scaling of Rates of Produced Fluids in Laboratory Displacements

Laroche

Chen²,

Yortsos³

et al. 2004

SPE Journal

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In a recent study, 1 it was shown that the ratio of the flow rates of the produced fluids in an immiscible displacement can be used to identify geometrical and petrophysical characteristics of a reservoir. In this paper, we develop an extended version of this approach and apply it to displacements in 1D laboratory cores. Because of the possible importance of capillary effects, we derive asymptotic theories for the time dependence of the produced fluid ratio in the limits where capillary is negligible and where it dominates, respectively. Attention is paid to the capillary end effect at the outlet and to late times.It is shown that the exponent in the power-law dependence of the relative permeability to saturation, near its residual value, can be determined from a segment of the curve of the outlet fractional flow sometime after breakthrough. The asymptotic predictions are verified by obtaining an analytical solution to the full problem, including end effects, for a model case corresponding to Burgers' equation. Solutions are obtained for both drainage and imbibition. Experimental results for the high-rate displacement of some gas/ liquids pairs are then reported. In agreement with the theoretical predictions, a power-law segment in the outlet fractional flow curve can be identified before capillary effects set in. The exponents obtained are discussed in terms of pore-scale models for gas/liquid displacement.

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Hydraulic Conductivity of Porous Media at Low Water Content

Cited by 129 publications

References 0 publications

Understanding NMR relaxometry of partially water-saturated rocks

Understanding NMR relaxometry of partially water-saturated rocks

Two Fractal Regimes of the Soil Hydraulic Properties

Time Scaling of Rates of Produced Fluids in Laboratory Displacements

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