The effect of indigenous microorganisms on water-rock interaction during the geological storage of CO2

The authors studied the influence of indigenous microorganisms on dissolution and precipitation of the minerals under conditions of high-pressure CO2 presence in deep saline geological formations. A series of experiments in shake flasks at ambient pressure and autoclaves were performed, in order to simulate the underground temperature, pressure and water environment. The results showed that calcium carbonate deposited on the surface of the minerals with the growth of bacteria. However, the dissolution rate of some carbon sequestration ions increased with the growth of fungi. Deposition amounts of iron carbonates on the surface of the minerals were enhanced by the growth of actinomycetes. Both the bacteria experiments and the autoclave experiments showed a kind of un-identified mineral precipitated on the surface of the rock samples, which potentially promoted the fixing of CO2 in underground. If the reaction time was long enough, the bicarbonate could turn into some carbonate minerals, such as CaCO3, MgCO3, and FeCO3. Thus, it is possible to store CO2 underground permanently.