A unified approach to evaluation of asphaltene precipitation based on laboratory measurement and modeling is presented. This approach uses an organic deposition cell (ODC) for measuring asphaltene-dropout onset conditions. Asphaltene precipitation was detected by changes in optical fluorescence, electrical conductance, and visual observation. A series of experiments measured the effects of changing pressure, temperature, and composition on asphaltene precipitation. A fully compositional vapor/liquid/solid (V/L/S) mathematical model completed the analysis by matching the experimental results. We then used the model to forecast asphaltene precipitation under a variety of production scenarios, including response to gas-lift operations, and to evaluate the possible location of a tar mat.