Non-isothermal reactive transport modelling of dissolved CO2 leaking through a fractured caprock
(English)Manuscript (preprint) (Other academic)
Geological storage of CO2 is considered as one of the mitigation actions for climate change adverse effects. However, some fraction of CO2 dissolved in the brine following injection, may leak from the reservoir through permeable zones such as conducting fractures. In this study we perform the reactive transport modelling of single-phase brine saturated with dissolved CO2 (CO2aq) along a conducting fracture in a clay-rich caprock. This study investigates the role of temperature and various reaction systems on the fate of migrating CO2aq, its geochemical interactions with the carbonate minerals, its conversion in geochemical reactions and associated medium porosity and permeability evolutions along the transport pathway.About 0.64% of leaking CO2aq is found converted into other ions in its geochemical interactions with calcite (simplified geochemical system). Addition of mineral dolomite in the geochemical system (extended geochemical system) results in up to 11% higher mass conversion of CO2 in reactions as compared to the simplified geochemical system. Considering extended geochemical system and heat transport by moving brine resulted in about 27.34% higher mass conversion of CO2 in reactions as compared to the simplified geochemical system. A combination of extended geochemical system, heat transport and sorption resulted in about 82.59% higher mass conversion of CO2 compared to the simplified geochemical system. Leaking CO2aq travelled less than 250 m along the fractured pathway, for a velocity of nearly 19 m/year in the fracture, due to retardation caused by mass stored in aqueous and adsorbed states.
Reactive transport, Brine carrying dissolved CO2, Conducting fracture, Kinetics of calcite and dolomite, Heat transport, Sorption
Mineral and Mine Engineering
Research subject Applied and Computational Mathematics; Chemical Engineering; Civil and Architectural Engineering; Land and Water Resources Engineering
IdentifiersURN: urn:nbn:se:kth:diva-184623OAI: oai:DiVA.org:kth-184623DiVA: diva2:916393
This manuscript was submitted to the journal of Water Resources Research. The main funder for this study has been “Higher Education Commission (HEC) of Pakistan”. The study was also partly supported by Lars Erik Lundberg Scholarship Foundation, Sweden.2016-04-012016-04-012016-04-04Bibliographically approved