Greensites and brownsites: Implications for CO2 sequestration characterization, risk assessment, and monitoring

Greensite pore fluids are typically unperturbed and relatively stable, providing a simpler environment for characterization and monitoring. Brownsite reservoir fluids, however, may have been modified by resource recovery. Geologic processes commonly have introduced trace hydrocarbons into the shallow subsurface. At the surface, brownsite legacy infrastructure and contamination must be evaluated so that preinjection transients do not mimic or mask leakage signals. To be effective, policies and regulations need to recognize inherent differences between greensites and brownsites during CO2 storage project development.