Natural gas accumulations with high CO2 concentrations may be useful natural analogs for the study of long-term CO2 storage in geologic strata if viewed in the context of ?CO2 systems?. Comprehensive evaluation of a CO2 system involves the identification of the following parameters: (1) the source and timing of CO2 generation, (2) the CO2 migration pathways, (3) the timing of CO2 migration, and (4) the locations and nature of CO2 traps and seals. The following three examples are described in terms of CO2 systems: (1) the Ellenburger Fields of West Texas, (2) the Leadville Fields of the Paradox Basin, and (3) the Big Escambia Creek and Flomaton Fields of Mississippi. The USGS is applying this concept to the Indian Creek Field of West [...]
