Imaging Fluid Movements Through Sandstones, Sands and Model Glass-Bead Packs Using Fast NMR Imaging Techniques

Nuclear Magnetic Resonance (NMR) techniques are extremely powerful for characterising and quantifying the properties of the fluid-rock systems. Magnetic Resonance Imaging (MRI) has an additional attraction in that it can be used to generate image contrast through fluid transport properties. The imaging experiments on such systems can be performed as static¹ or dynamic^2,3 fluid measurements. In some cases results of static-fluid measurements (eg. pore size distribution) are used to calculate a property that is more appropriately related to dynamic-fluid measurements (eg. permeability) In this work, an efficient flow mapping technique called Pi-Echo-Planar-Imaging (π-EPI or Pi-EPl or PEPI) was used to quantify flow through different porous materials, ranging from model glass bead packs to unconsolidated sand specimens to consolidated sandstone samples. The results presented demonstrate the potential of the high-speed snap-shot PEPI technique for quantitative spatial flow measurements in porous media. The fluid flow studies on different porous samples seem to indicate a linear relation between the mean flow velocity and the velocity variance within a selected slice. A detailed simulation model for the interpretation of these results is described elsewhere⁴. These results are still at the beginning of EPI applications in dynamic studies of porous media. Research protocols in this area are still at a relatively early stage and a far wider range of remaining challenges still exist⁵.