Asphaltene precipitation is one of the most common problems faced by the oil industry throughout the world during oil production, transportation and refinery processes. In oil recovery, especially in gas injection, formation of asphaltene aggregation, following their deposition can result in plugging of the formation, well bore and production facilities and makes the process costly and sometimes uneconomical. Unfortunately, there is no predictive model for asphaltene problem treatment because the mechanisms of asphaltene precipitation and deposition are still under investigation due to their complexity. The main purpose of this book was to study the mechanisms of asphaltene deposition in a porous medium. As part of this research book, a substantial number of experiments were performed to investigate the effect of different parameters on the amount of asphaltene precipitation. A slim tube filled with glass beads was selected as synthetic porous medium and some flood tests at different temperatures, oil to solvent volume ratios and various injection rates were carried out. A mathematical model was developed for prediction of permeability impairment due to asphaltene deposition.