Our research objective is to understand the evolution of the fracture behavior of host rock during CO2 sequestration. We focus our study on the Mt. Simon sandstone as part of the Illinois Basin Decatur Project, Illinois, USA. We conduct microscopic scratch tests, ion chromatography tests, environmental back-scattered secondary electron microscopy, and machine learning modelling on both unaltered and altered Mt Simon sandstone. Alteration occurs via incubation in CO2-saturated brine for seven days at 2500 psi and 50 ℃. The size effect law is applied to extract the fracture parameters from the scratch test measurements. A decrease in fracture toughness and an increase in fracture process zone is observed following incubation of Mt Simon sandstone in CO2-saturated brine. Furthermore, microstructural changes are observed such as an increase in the overall porosity, an increase in pore throat sizes, and the formation of local porosity gradients. Evidence of K-feldspar dissolution is shown as well. Thus, scratch testing provides a means to quantify the changes in fracture response following potential CO2-induced geochemical reactions, making the method suitable for quality control and safety design in CO2 geological sequestration schemes.
|Original language||English (US)|
|Title of host publication||10th International Conference on Fracture Mechanics of Concrete and Concrete Structures, FraMCoS-X|
|Editors||G Pijaudier-Cabot, P Grassl, C La Borderie|
|Number of pages||10|
|State||Published - 2019|