Use of Nuclear Magnetic Resonance as an Experimental Probe in Multiphase Systems: Determination of the Instrument Weight Function for Measurements of Liquid‐Phase Volume Fractions

Maneval, James E.; McCarthy, Michael J.; Whitaker, Stephen

doi:10.1029/wr026i011p02807

Cited by 9 publications

(6 citation statements)

References 34 publications

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“…This yields an approximately 0.58-mm3 spatial resolution called a voxel. A more exact analysis of the structure of this voxel was determined by Maneval et al (1990). Regardless of the exact voxel shape, this volume is considerably larger than the 9.7 x mm3 occupied by a single rayon fiber.…”

Section: Sedimentation Profilesmentioning

confidence: 99%

Hindered settling of rod‐like particles measured with magnetic resonance imaging

et al. 1995

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Section: Sedimentation Profilesmentioning

confidence: 99%

Hindered settling of rod‐like particles measured with magnetic resonance imaging

et al. 1995

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“…Oliver [1990] used a perturbation approach to calculate the weighting function for permeability estimates derived from the semilog plot of drawdown versus time for nonsteady pump test data. Weighting functions have been developed according to theoretical means for a number of other problems, including measurement of porosity by flow-through borehole tests using a radioactive tracer [Moltyaner, 1989], measurement of liquid phase porosity by 'nuclear magnetic resonance imaging [Maneval et al, 1990], and measurement of soil water content by time domain reflectomerry [Knight, 1992].…”

mentioning

confidence: 99%

What does an instrument measure? Empirical spatial weighting functions calculated from permeability data sets measured on multiple sample supports

Tidwell¹,

Gutjahr²,

Wilson³

1999

Water Resources Research

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Abstract. With the aid of linear filter theory we analyze 13,824 permeability measurements to empirically address the question, What does an instrument measure? By measure we mean the sample support or sample volume associated with an instrument, as well as how the instrument spatially weights the heterogeneities comprising that sample support. Although the theoretical aspects of linear filter analysis are well documented, physical data for testing the filtering behavior of an instrument, particularly in the context of porous media flow, are rare to nonexistent. Our exploration makes use of permeability data measured with a minipermeameter on a block of Berea sandstone. Data were collected according to a uniform grid that was resampled with tip seals of increasing size (i.e., increasing sample support). Spatial weighting (filter) functions characterizing the minipermeameter measurements were then calculated directly from the permeability data sets. In this paper we limit our presentation to one of the six rock faces, consisting of 2304 measurements, as the general results for each rock face are similar. We found that the empirical weighting functions are consistent with the basic physics of the minipermeameter measurement. They decay as a nonlinear function of radial distance from the center of the tip seal, consistent with the divergent flow geometry imposed by the minipermeameter. The magnitude of the weighting function decreases while its breadth increases with increasing tip seal size, reflecting the increasing sample support. We further demonstrate, both empirically and theoretically, that nonadditive properties like permeability are amenable to linear filter analysis under certain limiting conditions (i.e., small variances). Specifically, the weighting function is independent of the power average employed in its calculation (e.g., arithmetic versus harmonic average). Finally, we examine the implications of these results for other instruments commonly employed in hydraulic testing (e.g., slug and pump tests). Introduction Questions concerning what is actually measured by an in-In this way, the weighting function 13mo explicitly accounts for the influence of the measurement process on the value of k m.

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“…5, the T2 of the system varied as a function of position. Since the spatial resolution in the frequency encode direction is dependent upon T2* (Maneval et al, 1990) quantitation of saturations is not simple if T2* controls the spatial length scale. CONCLUSIONS THE SPIN ECHO TECHNIQUE has been successfully applied to study a two-phase oil water model.…”

Section: Creaming Of Oil In An Unstable Emulsionmentioning

confidence: 99%

Noninvasive Measurement of Lipid and Water in Food Using Magnetic Resonance Imaging

Winkler

McCarthy

German

1991

Journal of Food Science

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Structural properties and quality of many foods depend on changes in the state and distribution of food components. However, information on distribution of food components and their role in providing structure has been difficult to investigate in foods. Noninvasive, dynamic measurement of foods was investigated with nuclear magnetic resonance imaging to simultaneously investigate lipid and water separately. Different relaxation values exhibited by each component allowed resolution of oil and water through relaxation weighted images. This approach is applicable to study of food structure, dynamics, and component interactions.

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Use of Nuclear Magnetic Resonance as an Experimental Probe in Multiphase Systems: Determination of the Instrument Weight Function for Measurements of Liquid‐Phase Volume Fractions

Cited by 9 publications

References 34 publications

Hindered settling of rod‐like particles measured with magnetic resonance imaging

Hindered settling of rod‐like particles measured with magnetic resonance imaging

What does an instrument measure? Empirical spatial weighting functions calculated from permeability data sets measured on multiple sample supports

Noninvasive Measurement of Lipid and Water in Food Using Magnetic Resonance Imaging

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