CO2 Injection and Sequestration in Depleted Oil and Gas Fields and Deep Coal Seams: Worldwide Potential and Costs

Abstract Three petroleum extraction technologies offer potential for largescale, low-cost, and long-term sequestration of carbon dioxide. Enhanced oil recovery (EOR) using CO2 injection is a commercially proven process with more than 120 Gt of “value added” CO2 sequestration potential worldwide. Enhanced gas recovery (EGR) using CO2 injection is conceptually feasible but has not yet undergone testing. Depleted natural gas fields offer more than 750 Gt of moderate-cost CO2 sequestration potential, not including EGR. Enhanced coal-bed methane (ECBM) recovery using CO2 injection is undergoing pilot testing in the United States, with favorable early results. ECBM could be used to sequester more than 150 Gt of CO2 in coal basins worldwide. Challenges facing large-scale application of geologic sequestration in hydrocarbon fields include: (1) high capture and processing costs of anthropogenic CO2; (2) inadequate understanding of many petroleum and coal reservoirs, particularly in frontier areas; (3) rigorous monitoring and verification to convince regulators and the public at large that sequestration is secure and long term; (4) achieving recognition and certification from emissions trading systems; and (5) resolving operational conflicts between sequestration and enhanced recovery. These challenges could be overcome by building on existing technologies from the EOR, underground gas storage, and natural CO2 production and transportation industries and by targeted basic and applied R&D. Key Words: CO2, geologic sequestration, enhanced oil recovery, enhanced coal-bed methane recovery, economics.