Agca, C., Pope, G.A. and Sepehrnoori, K., 1990. Modelling and analysis of tracer flow in oil reservoirs. In: M. Sardin and D. Schweich (Editors), Impact of Physico-Chemistry on the Study, Design and Optimization of Processes in Natural Porous Media. J. Pet. Sci. Eng., 4: 3-19. Tracer flow in oil reservoirs has been studied using a finite difference compositional reservoir simulator (UTCHEM). One of the applications of this type of study is to aid in reservoir characterization. For this purpose several tracer components have been added to UTCHEM. These tracers can partition between oil and water, adsorb on the rock surface and undergo radioactive decay. Comparisons with an analytical solution for a five-spot well pattern gave excellent agreement, which indicates the dispersion control scheme used works well. Actual field tracer data from the Big Muddy Field, Wyoming, were analyzed successfully taking into account reservoir heterogeneity based on core data, and both dispersion and adsorption of the tracers. Agreement with the data for both the tritium and thiocyanate tracers was excellent. This result illustrates the potential for quantitative analysis of oil field tracer flow and has great utility for modelling enhanced oil recovery processes in oil reservoirs.