| AVS 59th Annual International Symposium and Exhibition | |
| Nanometer-scale Science and Technology | Thursday Sessions |
| Session NS-ThM |
| Session: | Nanoscale Imaging and Microscopy |
| Presenter: | A.S. Lea, Pacific Northwest National Laboratory |
| Authors: | A.S. Lea, Pacific Northwest National Laboratory M. Xu, Pacific Northwest National Laboratory K.M. Rosso, Pacific Northwest National Laboratory |
| Correspondent: | Click to Email |
Geologic sequestration of CO2 has become an emerging enterprise for reduction of greenhouse gas emissions. Because CO2 will be injected and stored in host rock at depths >800m, lithostatic pressure will cause the CO2 to remain in supercritical fluid state. Knowledge of mineral-fluid chemical transformation rates at geologically relevant temperatures and pressures is expected to be an important aspect of predicting reservoir stability. Many mechanisms of mineral transformation reactions where scCO2 is the dominant phase and water availability is low have so far remained unstudied. We have developed an atomic force microscope capable of observing in-situ mineral transformations under supercritical conditions (i.e., >72.8 atm and >304K) in real time.
Observations of the disappearance of a 1.5nm layer on the surface calcite is evident in anhydrous scCO2 are consistent with the dehydration of a hydrated calcium carbonate layer and is consistent with measurements from piezoelectric force microscopy. We have also followed the formation of a water film on the surface of geologically more relevant forsterite, which is deemed to be essential in the transformation of this silicate mineral into a carbonate, and have related film thickness to water content in the scCO2.