ABSTRACT
Nuclear magnetic resonance (NMR) is a nondestructive technique that can be used to characterize a variety of systems and oil derivatives such as preserved reservoir rock samples, micro-and macro-emulsions, as well as crude oils and their fractions, e.g., asphaltenes, resins, and organic acids. Different functional groups in a molecule resonate in unique, well-resolved spectral regions, and this fact has established NMR as a highly discriminative and quantitatively reliable analytical technique. NMR has been widely employed to characterize oil samples from different angles, including molecular structures, chemical composition, kinetic behavior, and oil-in-water dispersion stability. While analytical techniques, and NMR in particular, have been heavily used in downstream applications in the oil and gas industry, namely in refining and petrochemistry, the transfer and adaptation of some of these analytical techniques to upstream applications have been increasingly taking place in more recent times. High-field NMR has been the domain of analytical chemistry when it relates to these types of applications; however, low-field or time-domain NMR has fulfilled many of the needs in the upstream world. Relaxometry has become a mature and frequently used low-field NMR alternative, particularly with regard to characterization of porous media and heavy crude oils. Some of the most relevant work employing NMR in these areas is discussed in this chapter.
