The National Energy Technology Laboratory (NETL) is committed to helping the U.S. control emission of anthropogenic CO2. A significant new storage technique involves scrubbing or removal of CO2 from the flue gases of fossil fuel power plants and injection into underground geologic formations, thus sequestering or preventing its addition to the atmosphere. Ideally, geologic sequestration would result in mineral trapping, the process of forming in-situ, interstitial carbonate minerals from CO2 and the host rock and formation waters. To address the potential of brine aquifers as mineral trapping horizons, a number of published oil and gas well brine composition data bases were evaluated for the Oriskany Formation, Mt. Simon Formation and the Williston Basin. There was considerable variation in the number of chemical variables that were tabulated for the respective wells. To evaluate the variability of the ionic concentrations and pH among the data, a one-way analysis of variance model (ANOVA) was computed (p=0.05) for each formation. Although there are significant differences among the carbonate forming metal ions, the brine chemistry of the three aquifers shows that the units have the potential to sequester anthropogenic CO2. A limiting factor for the carbonation reaction however may be the acidic nature of some of the brines.