The applications of nuclear magnetic resonance (NMR) to petroleum exploration and production have become more and more important in recent years. The development of the NMR logging technology and the NMR applications to core analysis and formation evaluation have been very rapid and extensive.The scope of this book covers a wide range of NMR related petrophysical measurements on cores including brief descriptions of recent applications of Magic Angle Spinning (MAS) NMR and the basics of NMR imaging of cores. In the discussion of NMR logging applications various schemes of using NMR logs to obtain necessary information for formation evaluation are outlined, such as irreducible water saturation determination, hydrocarbon typing, oil viscosity estimation, and permeability prediction. The principles of these applications are discussed using schematic diagrams for illustration.A unique aspect of the book is that it provides a detailed account of the basic principles of spin diffusion and relaxation in porous media. Another important area that is covered is the inversion of NMR data into a distribution of amplitudes associated with relaxation time which provides the basic information needed to interpret the NMR measurements obtained from logging.