CO2 sequestration in a deep saline aquifer was simulated using a compositional commercial simulator based on a single-well aquifer model, which was developed to analyze the injection and storage process of CO2 under supercritical and gaseous conditions for long periods of time. The influence of controlling parameters including vertical to horizontal permeability ratio, aquifer pressure, injection rate on the isothermal injection, and sequestration processes were investigated and the sensitivity analysis corresponding to those processes was performed. The results of this parametric study showed that these controllable parameters have a significant influence on CO2 sequestration process and should be well optimized for effective sequestration processes in a deep saline aquifer. The present study indicated that vertical to horizontal permeability ratio (k(v)/k(h)) and initial pressure conditions were the most dominating parameters affecting the free CO2 saturation at the injection well block in each layer of the aquifer; whereas, free CO2 saturation level in the middle and bottom layers was strongly affected by CO2 injection rate. This can be attributed to the fact that an increase in k(v)/k(h) ratio caused an increase in free CO2 saturation level in top layer; whereas, free CO2 saturation level decreased with an increase in k(v)/k(h) ratio in the middle and bottom layers due to the high tendency of free CO2 to rise up.