Flow and diffusion measurements in natural porous media using magnetic resonance imaging.

Flow and diffusion of water in natural porous media, quartz sand, and calcareous gravel were measured using a 1.5-T clinical magnetic resonance tomograph. The spatial resolution of the dynamic measurements was 1.32 x 1.32 x 5 mm3, and the time between two cross-sectional measurements was approximately 10 s. The measured coefficients of molecular diffusion for water were in good agreement with theoretical data. Flow was measured without any tracer at velocities between 0.15 and 6.67 mm/s. The results, based on a calibration within one part of the column, were in good agreement with data obtained from a tracer experiment and from a numerical model. It was possible to measure the flow velocity in larger pores and preferential flow paths directly. The results of the flow measurements in smaller pores reflected the mean velocity within that volume element. In that case the obtained values were close to the average linear velocity. Since the time resolution is high a monitoring of flow processes is possible. The pore space was imaged with a spatial resolution of 0.5 x 0.5 x 0.5 mm3. Here, the porosity of pores that are larger than 0.2 mm can be measured directly; for smaller pores a calibration is necessary.

[1]  L. Bailey,et al.  X-ray tomography vizualization and mechanical modelling of swelling shale around the wellbore , 1993 .

[2]  Lee A. Feldkamp,et al.  Microscopic Imaging of Porous Media With X-Ray Computer Tomography , 1993 .

[3]  Sharon E. Roosevelt,et al.  Micromodel visualization and quantification of solute transport in porous media , 1997 .

[4]  M. Elimelech,et al.  Kinetics of Colloid Deposition onto Heterogeneously Charged Surfaces in Porous Media. , 1994, Environmental science & technology.

[5]  W. Kinzelbach,et al.  Observation of flow and transport processes in artificial porous media via magnetic resonance imaging in three dimensions , 1997 .

[6]  Stephen P. Garabedian,et al.  Use of colloid filtration theory in modeling movement of bacteria through a contaminated sandy aquifer , 1991 .

[7]  J. E. Tanner,et al.  Spin diffusion measurements : spin echoes in the presence of a time-dependent field gradient , 1965 .

[8]  R J Seitz,et al.  Diffusion- and perfusion-weighted MRI. The DWI/PWI mismatch region in acute stroke. , 1999, Stroke.

[9]  Hans-Jörg Vogel,et al.  Morphological determination of pore connectivity as a function of pore size using serial sections , 1997 .

[10]  A Haase,et al.  Fast NMR flow measurements in plants using FLASH imaging. , 1999, Journal of magnetic resonance.

[11]  S. Akin,et al.  A novel method of porosity measurement utilizing computerized tomography , 1996 .

[12]  W. Nitz,et al.  MR imaging: acronyms and clinical applications , 1999, European Radiology.

[13]  C. Welty,et al.  Stochastic analysis of virus transport in aquifers , 1999 .

[14]  A. Sharpley,et al.  Hydrologic Controls on Phosphorus Loss from Upland Agricultural Watersheds , 1998 .

[15]  J. McCarthy,et al.  Subsurface transport of contaminants , 1989 .

[16]  Atuo Nishioka,et al.  High Resolution NMR , 1974 .

[17]  P. J. Whiting,et al.  Climatic and agricultural factors in nutrient exports from two watersheds in Ohio. , 2002, Journal of environmental quality.

[18]  F. J. Holler,et al.  Principles of Instrumental Analysis , 1973 .

[19]  M. Wiesner,et al.  Deposit Morphology and Head Loss Development in Porous Media , 1997 .

[20]  Hans-Jörg Vogel,et al.  A new approach for determining effective soil hydraulic functions , 1998 .

[21]  J. A. Chudek,et al.  An application of nuclear magnetic resonance imaging to study migration rates of oil-related residues in estuarine sediments , 1998, Biodegradation.

[22]  P. Gschwend,et al.  Sorption kinetics of hydrophobic organic compounds to natural sediments and soils. , 1986, Environmental science & technology.