NMR imaging of fluids in porous solids

The principles governing the NMR behaviour of 1 H-containing fluids permeating porous solids, such as hydrocarbon reservoir rocks, are outlined. The additional capabilities of NMR imaging methods for characterizing these systems is considered. Experimental results are presented for NMR imaging applied to a model porous solid (alumina) and natural sandstone and limestone rocks, saturated with aqueous phases. Both three-dimensional and slice-selected two-dimensional FT spin echo methods are used and the images demonstrate the capability of NMRI in these systems to reveal internal structures of the porous solids. Simple strategies for characterizing the spatial heterogeneity of these materials in terms of histograms and correlation functions are proposed and a general pixel fitting program is used to examine some of the data in terms of such histograms and related property maps.