An experimental study, as well as theoretical and numerical models, are used to validate a methodology to exploit conventional geochemical data with regard to the concentration profiles of organic components occurring naturally in hydrocarbon reservoir oils. The experiment was designed to study transport of organic compounds from bypassed oil during water injection using a homogeneous oil-filled core sample, which was made heterogeneous by drilling a hole through its central axis and filling it with a highly permeable material. Under the present conditions, diffusion coefficients are the most important parameters controlling the transport, and the effect of partitioning could be accounted for by a simple normalization. The experimental results are well described by a simple 2-D analytical model that assumes instantaneous removal of solutes from the oil-water interface. The experimental results are also well described by two numerical models, of which one is a full-featured reservoir scale model, suitable for applications of the methodology to reservoir-scale cases.