Injection of carbon dioxide into depleted oil fields is a commercially proven process used for enhanced oil recovery (EOR). At present, a total of 74 active CO2-EOR projects sequester an estimated 30 Mt Of CO2 (8 MtC) in the U.S. annually, including 5 Mt of anthropogenic waste CO2. This study evaluated the global capacity, costs and technical feasibility of sequestering CO2 in depleted oil and natural gas fields. An economic model of sequestration in 155 worldwide geologic provinces was constructed to generate CO2 sequestration capacity/cost curves. Global sequestration capacity is estimated to be 923 Gt Of CO2. Assuming $20/bbl oil prices and $100/tC CO2 Supply costs, an estimated 34 GtC could be sequestered at low costs (net profit to $50/tC) in EOR projects worldwide. At zero CO2 supply cost, as much as 141 GtC of disposal capacity would be available in depleted oil and gas fields. Barriers to wider implementation include 1) high costs of capturing, processing, and transporting anthropogenic CO2; 2) incomplete understanding of reservoir processes; 3) underdeveloped monitoring and verification technologies; 4) unclear emissions trading regulations; and 5) potential conflicts between sequestration and EOR or natural gas recovery. However, with continued R&D, technologies used by the EOR, underground gas storage, and natural CO2 production industries could be adapted to achieve secure and low-cost sequestration in depleted oil and gas fields.
