VAPEX is a solvent-based gravity drainage process that follows exactly the same well configuration as in SAGD. In the last decades, several researchers have investigated many aspects of the process, both theoretically and experimentally. However, there are only few reported attempts on numerical simulation of VAPEX; therefore. the feasibility and/or any potential pitfalls of VAPEX numerical modeling with current commercial simulators remain unclear. This paper discusses several aspects of lab-scale VAPEX modeling and addresses some of the associated difficulties and obstacles along with possible Solutions. This was achieved by history matching the lab-scale VAPEX experiments, employing a commercial compositional simulator. The outcome of this study shows that it is still not possible to fully capture the physics of the process with current commercial modeling tools. An extremely thin mass-transfer transition zone is to be modeled with very fine grid Systems along with precise numerical constraints, and this requires exculsive and accurate PVT data and viscosity model for every specific oil-solvent system. The analysis of the results also indicates that numerical dispersion is a serious hurdle that clouds the modeling Outputs, if not carefully treated.