Coupled chemical-mechanical processes associated with the injection of CO2 into subsurface
The long-term carbon dioxide storage capacity of reservoirs can be impacted by chemical reactions, mass transport, and mechanical deformation of the reservoir and caprock following the injection of CO2. Mineral mass removal can lead to microcracking and compaction, thus affecting the mechanical integrity of the reservoir-caprock system. The short-term (days, months) and long-term (hundreds to thousands of years) chemical effects, such as the dissolution of intergranular cement and mineral precipitation, can lead to a coupled chemical-mechanical response. This chemical-mechanical coupling occurs at multiple temporal and spatial scales. For instance, chemical processes at the crack-tip (micrometer) scale affect fracture networks with complex fracture architecture all the way to the reservoir scale. This chapter addresses chemical effects on the mechanical response of reservoir and caprock lithologies considered for geological carbon storage. Particular emphasis is on sandstone reservoir and mudrock (shale) caprock, as they are the most typical formations targeted for the injection of CO2. This chapter examines the existing laboratory, field, and modeling studies that address the coupled chemical-mechanical response of sandstone and mudrock lithologies to the injection of CO2. These coupled chemical-mechanical responses during geological carbon storage can result in the development of preferential flow paths and CO2leakage.
