CARBON DIOXIDE SEQUESTRATION WITH BRINES

Permanent sequestration of carbon dioxide can reduce the green house gas effect generated from combustion of fossil fuels. Injection of carbon dioxide into saline aquifer formations is one option in geologic sequestration of carbon dioxide. The estimated carbon storage capacity of saline formations in the United States is large, making them a viable long-term solution. Carbon dioxide can be trapped in saline aquifers via mineral trapping. Various carbonates such as calcite, dolomite, and siderite can be formed in the brine aquifer by mineral trapping. The extended time, however, required for mineral trapping is the major concern of this process.

In this study, accelerated mineral trapping experiments with brine solutions under controlled conditions have been initiated. Brine solutions were tested in a half-liter autoclave under various conditions. Preliminary results indicate that the mineral species type and amount of solid precipitation depend on the pH of the brine and the reaction conditions utilized. In addition, the reactions were modeled with an advanced geo-chemical code. The computer simulation includes all the possible chemical reactions for the formation of carbonates and various reaction parameters including temperature, pressure, ionic concentration, and pH. The combined experimental and modeling data suggest that pH plays a key role in the formation of carbonate minerals. The effects of temperature and carbon dioxide pressure have less impact on the formation of carbonates.