A method and apparatus for obtaining a parameter of interest relating to a region proximate a nuclear magnetic resonance (NMR) logging tool suitable for subterranean well logging is disclosed. The nuclei of the region are subjected to a pulsed NMR technique and are productive of NMR logging data, the nuclei of the region characteristically having a longitudinal relaxation time T.sub.1 distribution and an apparent transverse relaxation time T.sub.2app distribution. In response to the NMR logging data, an R distribution is defined as R=T.sub.1/T.sub.2app, the T.sub.2app and R distributions are processed as separate bins, along with the NMR logging data, according to a two-dimensional inversion model, and a signal intensity map of R versus T.sub.2app is provided that is representative of the parameter of interest relating to the region. In response to a high-intensity signal on the map being within a first range of T.sub.2app values and a first range of R values, the presence of a light hydrocarbon within the region is identified.