Carbon dioxide capture and storage (CCS) is emerging as a key technology for greenhouse gas (GHG) mitigation. The Society of Petroleum Engineers (SPE) Applied Technology Workshop (ATW) on CO2 Sequestration (Galveston Island, Texas, Nov. 15–17, 2005) convened a diverse group of geoscience, engineering, economics and stakeholder experts to review the status of CCS and to identify the remaining critical issues that still serve as barriers to its acceptance and widespread deployment.
Site assessment can be improved with systematic, generally accepted approaches that identify and focus on injection, capacity and containment risks. Reservoir simulation models can be adapted from oil and gas applications but further experimental work and code development are needed to quantify the role of major CO2 trapping mechanisms. Enhanced hydrocarbon recovery accompanying injection of CO2 is well established for CO2 EOR but its efficacy in EGR and ECBM is unclear. Well integrity, a key vulnerability in CO2 storage, should be addressed through modified well materials and construction approaches and cost effective remediation and intervention techniques. Field management issues, including risk assessment and monitoring, would benefit from development of accepted practices to apply through project lifecycle.
Overall, the Workshop participants concluded that implementation of CCS, in a timely manner, represents a complex challenge that requires coordination of technical expertise, economic incentives, appropriate regulations and public acceptance. Storage assessment tools are available and adequate, although in need of refinement and standardization. Capture technology, however, requires more intense research aimed at new technologies and deep cost reduction. Infrastructure and regulatory development needs to reflect expectations and incentives from government bodies. Early implementation of CCS is expected to focus on the gas processing and other industries that produce high purity CO2 with storage in local hydrocarbon reservoirs or saline aquifers. Deployment at a scale required to substantially reduce CO2 atmospheric concentrations, however, would rely heavily on injection into saline formations and take decades of investment to build the extensive infrastructure required to capture and transport CO2 to injection sites.
The ATW gathering was a unique, timely opportunity to engage experts in an assessment of the status and best path forward for CCS.
Current and projected rates of CO2 emissions from fossil fuels may lead to changes in global climate with significant impact. Whereas improved energy efficiency and renewable energy will play growing roles in this century, fossil fuels will continue to meet the majority of energy needs for decades to come (IEA/OECD World Energy Outlook 2004). Even with technical advances and changes in the energy mix and its efficient use, there is an expanding gap over the present century between projected emissions and those emissions levels needed to stabilize atmospheric CO2 to desired levels (Edmonds et al., 2004)1.