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Non-isothermal reactive transport modelling of dissolved CO2 leaking through a fractured caprock
KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Hydraulic Engineering. KTH Royal Institute of Technology. (Doctoral Program in Land and Water Resources Engineering)ORCID iD: 0000-0002-6871-8540
KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Hydraulic Engineering.ORCID iD: 0000-0003-2726-6821
Stockholm University, Sweden. (Department of Physical Geography, The Bolin Centre for Climate Research, Stockholm University, SE-10691 Stockholm, Sweden)
Universitat Politècnica de Catalunya, UPC-BarcelonaTech, 08034 Barcelona, Spain. (Hydrogeology Group, Department of Geotechnical Engineering and Geosciences, Universitat Politècnica de Catalunya, UPC-BarcelonaTech, 08034 Barcelona, Spain)
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(English)Manuscript (preprint) (Other academic)
Abstract [en]

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.

Keyword [en]
Reactive transport, Brine carrying dissolved CO2, Conducting fracture, Kinetics of calcite and dolomite, Heat transport, Sorption
National Category
Mineral and Mine Engineering
Research subject
Applied and Computational Mathematics; Chemical Engineering; Civil and Architectural Engineering; Land and Water Resources Engineering
Identifiers
URN: urn:nbn:se:kth:diva-184623OAI: oai:DiVA.org:kth-184623DiVA: diva2:916393
Funder
StandUp
Note

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.

Available from: 2016-04-01 Created: 2016-04-01 Last updated: 2016-04-04Bibliographically approved
In thesis
1. REACTIVE TRANSPORT MODELLING OF DISSOLVED CO2 IN POROUS MEDIA: Injection into and leakage from geological reservoirs
Open this publication in new window or tab >>REACTIVE TRANSPORT MODELLING OF DISSOLVED CO2 IN POROUS MEDIA: Injection into and leakage from geological reservoirs
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The geological sequestration of carbon dioxide (CO2) is one of the options of controlling the greenhouse gas emissions. However, leakage of CO2 from the storage reservoir is a risk associated with geological sequestration. Over longer times, large-scale groundwater motion may cause leakage of dissolved CO2 (CO2aq).

The objectives of this thesis are twofold. First, the modelling study analyzes the leakage of CO2aq along the conducting pathways. Second, a relatively safer mode of geological storage is investigated wherein CO2aq is injected in a carbonate reservoir. A reactive transport model is developed that accounts for the coupled hydrological transport and the geochemical reactions of CO2aq in the porous media. The study provides a quantitative assessment of the impact of advection, dispersion, diffusion, sorption, geochemical reactions, temperature, and heat transport on the fate of leaking CO2aq.

The mass exchange between the conducting pathway and the rock matrix plays an important role in retention and reactions of leaking CO2aq. A significant retention of leaking CO2aq is caused by its mass stored in aqueous and adsorbed states and its consumption in reactions in the rock matrix along the leakage pathway. Advection causes a significant leakage of CO2aq directly from the reservoir through the matrix in comparison to the diffusion alone in the rock matrix and advection in a highly conducting, but thin fracture. Heat transport by leaking brine also plays an important role in geochemical interactions of leaking CO2aq

Injection of CO2aq is simulated for a carbonate reservoir. Injected CO2-saturated brine being reactive causes fast dissolution of carbonate minerals in the reservoir and fast conversion of CO2aq through considered geochemical reactions. Various parameters like dispersion, sorption, temperature, and minerals reaction kinetics are found to play important role in the consumption of CO2aq in reactions.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2016. xii, 59 p.
Series
TRITA-LWR. PHD, ISSN 1650-8602 ; 2016-04
Keyword
CO2 geological storage and safety, leakage of brine saturated with dissolved CO2, reactive transport, fracture, advection, dispersion and diffusion, sorption, carbonate minerals kinetic reactions, calcite, dolomite, siderite, porosity, permeability, heat transport
National Category
Mineral and Mine Engineering
Research subject
Land and Water Resources Engineering
Identifiers
urn:nbn:se:kth:diva-184204 (URN)978-91-7595-911-5 (ISBN)
Public defence
2016-04-20, F3, Lindstedstsvägen 26, KTH, Stockholm, 10:00 (English)
Opponent
Supervisors
Funder
StandUpSwedish Research Council, VR621-2007-4440
Note

Research Funders:

(i) Higher Education Commission (HEC) of Pakistan

(ii) Lars Erik Lundberg Scholarship Foundation, Sweden

Available from: 2016-04-04 Created: 2016-03-30 Last updated: 2016-05-02Bibliographically approved

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