In an oil and gas industry processes, high emission of CO2 is commonly happening and become a serious environmental issue. Some of the oil and gas industries have been implementing the CO2 storing technology called Carbon Capture Storage (CCS). However, there are less restrictions and consideration to calculate the capacity of the CCS reservoir. This problem will make the storage assessor use a lot of assumptions and less accuracy in the result. Finally, risks associated with the storage capacity and its integrity remain unresolved problem. This study will be focusing on estimating the storage capacity and maximum injection time for a multilayer reservoir in which the basic model will be generated from East Natuna Basin. CMG-GEM will be used as the software to model this field. The experiment case used in this model will be trained by CMG-CMOST. In determining the range of each parameter for the experiment case, there will be an analysis from a total of 10 fields of CCS in the world. The objective function in the CMG-CMOST is the storage capacity and estimated allowable injection time which will use a total of 620 experiments with a combination of 11 parameters. The results of sensitivity analysis will be simplified by Eureqa software which could be used for both single and multilayer reservoir with a confidence level of 96.6% for storage capacity and 95.4% for maximum injection time. Furthermore, there are other case studies for three CCS field to show the capability of the proposed equations.