9.2 Potential role of CO2 EOR in CCS
CO2 EOR has long been of interest to the CCS community as an opportunity for developing technical knowledge and for study of large-scale field deployment of CO2 injection. Increasingly, however, it is being viewed as a likely means of advancing CCS deployment more broadly. This is largely because CO2 EOR can provide or support a business case for the capture and delivery of CO2, thereby fostering development and improvement in capture methods and ultimately lowering their associated costs. In turn this may expand infrastructure and distribution networks to access additional storage sites, which will lead to gains in scientific and technical knowledge around aspects of geologic storage including risk management, monitoring and verification, and modelling and simulation of the subsurface behaviour of CO2.
Natural gas processing, the production of ammonia and ethanol, ethylene plants, and coalall produce high concentrations of CO2 as part of their standard industrial processes and have a comparatively low cost of capture. These low-cost anthropogenic sources of CO2 are those typically used currently for EOR, and are serving as vanguards for the development of CCS as an integrated solution to carbon storage. Outside the US, A-CO2 is the largest source of CO2 for EOR. In the US, projects under construction and planning since 2010 have greater growth in A-CO2 than development of natural sources, and thus A-CO2 is expected to become increasingly important in the next decade. Current CO2 prices for EOR in the US are typically US$10–40/tonne (Godec 2011) and revenues from its sale can cover capture costs from low-cost anthropogenic sources. For CCS projects with relatively higher capture costs, such as power generation, revenue from CO2 sales can cover some, but not all, of the additional costs. In this way CO2 EOR can become an important element toward CCS development activity, particularly in North America but also in Europe, Latin America, the Middle East, and China.
Nonetheless, there are differences between a generic CO2 EOR operation and a CO2 EOR operation targeting the storage of A-CO2, including:
- anthropogenic CO2 must, clearly, be used as the source, as transferring natural CO2 from one geologic to another (the oil field) does not reduce emissions overall; and
- monitoring and verification activities currently associated with CO2 EOR are applied to optimise oil production, and not to establish baselines or demonstrate conformance and permanence of storage.
The mechanisms involved in the EOR process do result in permanent geologic storage of CO2 but in the absence of policy or other financial benefit, CO2 EOR sites will not be operated for CO2 storage. Most individual fields offer considerably more capacity for carbon storage potential than utilised in normal production operations, and apolicy would provide incentives for operators to store more CO2.