The research, whose primary goal was to gain a better understanding of the behaviour of injected CO2 in the sub-surface, was based on uncertainty analysis using simulations for leakage potential and capacity estimates for saline aquifers.
While the capacity simulations showed that there still remains large uncertainty when it comes to storage capacity estimates, the results for the leakage simulation looked rather different. According to the results, there is a certain probability of leakage. The actual amount of CO2 that leaks, however, is a matter of fractions of one percent of total injected volumes of CO2. In addition, it is in the scope of thousands of years that the leakage will eventually occur.
The complete thesis can be obtained from MIT`s website.