CO storage in depleted oil and gas reservoirs is an important approach to reducing anthropogenic CO emissions owing to its unique advantages. Carbon capture and storage (CCS) projects thus require a practical monitoring program to confirm that injected CO remains in reservoirs as intended and that any occurring leakage is promptly detected and corrected. To develop an eco-friendly and cost-effective monitoring program, this study proposes a multi-objective integer model with three considerations: environmental sustainability, economic savings, and reliable detection. The proposed model is then applied to a CCS project in Shaanxi, China, to demonstrate its efficiency and practicality. An enhanced strengthen elitist genetic algorithm is developed as the solution approach. The analyses and discussions under different scenarios yield interesting and valuable proposals. Corresponding management recommendations are proposed to improve practical operations.