Contrasts in the geochemical behavior of carbonate and siliciclastic rocks during carbon storage and sequestration

In order to better understand the geochemical behavior of carbonate and siliciclastic materials that may host carbon dioxide in the subsurface, we carried out experiments using a dolostone from the Weyburn formation and an arkosic sandstone from the Newark Basin. Synthetic brine (0.7 m NaCl) saturated with CO2 with or without CH4 reacted with the powdered materials for 30 to 60 days at 100 bars pressure and 50 – 150 °C. The reactivity of the material was monitored by release of elements from the rock to solution over time. A subset of experiments were carried out in which an acidic heavy metals solution was injected into a Weyburn experiment in order to simulate the release of metals to solution through injection of CO2-saturated brines. The results show that the heavy metals do not stay in solution and rapidly decrease in concentration to pre-injection levels after a few days’ time.