Michael Celia, Theodora Shelton Pitney Professor of Environmental Studies. Professor of Civil and Environmental Engineering. Director, Program in Environmental Engineering and Water Resources.
Carbon capture and sequestration (CCS) is the only currently available technology that can significantly reduce atmospheric carbon emissions while allowing continued use of fossil fuels for electric power generation and other industrial processes. CCS involves capturing the CO2 before it is emitted to the atmosphere, and injecting it into deep subsurface formations, thereby keeping it out of the atmosphere for centuries to millennia or longer. While conventional, high-permeability formations have traditionally been considered as injection targets, recent proposals suggest possible injection of captured CO2 into unconventional reservoirs with low permeability, specifically depleted shale-gas reservoirs. Injection into both conventional and unconventional formations involves a number of challenges, including the need for comprehensive environmental risk assessments and associated analysis of possible leakage scenarios. The use of unconventional formations has the additional challenge of low injection rates per well, leading to the need for large numbers of injection wells with associated logistical and economic issues. This presentation will focus on specific leakage risks in conventional formations and on logistical challenges for injection into unconventional reservoirs.