The development of new quantitative magnetic resonance imaging (MRI) technologies opennew opportunities for measurements of mass transport in porous media. The current work examines a simple miscible displacement process of H 2 O and D 2 O in porous media samples. Laboratory measurements of dispersion in porous media traditionally monitor the effluent intensity of an injected tracer. We employ MRI to obtain quantitative water saturation profiles, and to measure dispersion in rock core plugs. The saturation profiles are modeled with PHREEQC, a fluid transport modeling program. We demonstrate how independent magnetic resonance measurements can be employed to estimate three important input parameters for PHREEQC, mobile porosity, immobile porosity, and dispersivity. Bulk Carr Purcell Meiboom Gill (CPMG) T 2 distribution measurements were undertaken to estimate mobile and immobile porosity. Bulk alternatingpulsed-gradient-stimulated-echo (APGSTE) measurements were undertaken to measure dispersivity. The imaging method employed, T 2 mapping Spin Echo Single Point Imaging (SE-SPI), also provides information about the pore size distributions in the rock cores, and how the fluid occupancy of the pores changes during the displacement process.
Quantitative measurements are important for imaging fluid content in porous media. Conventional MRI methods suffer from contrast because of relaxation times in porous media, resulting in measurements of apparent fluid content, not the true fluid content. We compare four magnetic resonance imaging methods for fluid content imaging in several water-saturated reservoir core plugs: frequency-encoded spin echo, single point ramped imaging with T1 enhancement, hybrid spin echo single point imaging (SE-SPI), and T2 mapping SE-SPI. 1-D profiles obtained with each method were compared in terms of image quality, image sensitivity, and quantification of water content. The image quality of short T2 lifetime samples suffered from blurring in hybrid SE-SPI images. Image sensitivity was the highest in the profiles obtained with frequency-encoded spin echo. The quantification of frequency-encoded spin echo, T2 mapping SE-SPI, and hybrid SE-SPI suffered in core plugs with a significant population of short T2 components because of T2 attenuation. Overall, single point ramped imaging with T1 enhancement was found to be the most general method for fluid content imaging.
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