USE OF PRESATURATION FOR CHEMICAL-SHIFT-SELECTIVE IMAGING OF INDIVIDUAL FLUIDS IN SANDSTONE AND CARBONATE CORES

A number of approaches to chemical-shift-selective NMR imaging are possible, and several have been demonstrated in the literature. Many of these methods were originally developed for solvent signal suppression in Fourier transform NMR spectroscopy. We demonstrate here the use of RF presaturation to obtain chemical-shift-selective, fluid-specific images of refined oil and aqueous brine in carbonate and sandstone cores. This method of fluid-selective imaging has not been previously demonstrated for rock cores. In the sandstone case, by injecting perdeuterated isopropanol, it was further possible to obtain fluid-selective images for each of the three fluids present in the core. To our knowledge, this is the first demonstration by either NMR or X-ray CT imaging of fluid-selective images for three individual fluids in a rock. In addition, 3D reconstructions of the fluid-selective slice images are presented for the sandstone core. © 1991.