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Reactive transport modeling of leaking CO2-saturated brine along a fractured pathway
KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Hydraulic Engineering. Policy Wing, Ministry of Petroleum and Natural Resources, Government of Pakistan, Pakistan.ORCID iD: 0000-0002-6871-8540
KTH, School of Architecture and the Built Environment (ABE), Civil and Architectural Engineering, Hydraulic Engineering.
2015 (English)In: International Journal of Greenhouse Gas Control, ISSN 1750-5836, E-ISSN 1878-0148, Vol. 42, 672-689 p.Article in journal (Refereed) PublishedText
Abstract [en]

One concern regarding the underground storage of carbon dioxide (CO2) is its potential leakage from reservoirs. Over short period of time, the leakage risk is related mainly to CO2 as a separate supercritical fluid phase. However, over longer periods upon complete dissolution of injected CO2 in the fluid, the leakage risk is associated with dissolved phase CO2. Over the geological time scales, large-scale groundwater motion may cause displacement of brine containing dissolved CO2 along the conducting pathways. In this paper, we present a comprehensive modeling framework that describes the reactive transport of CO2-saturated brine along a fracture in the clay caprock based on the future, hypothetical leakage of the dissolved phase CO2. This study shows that the transport of leaked dissolved CO2 is significantly retarded by a combination of various physical and geochemical processes, such as mass exchange between conducting fracture and the neighboring rock matrix through molecular diffusion, sorption and calcite dissolution in the rock matrix. Mass stored in aqueous and adsorbed states in the rock matrix caused retention of dissolved CO2 along the leakage pathway. Calcite dissolution reaction in the rock matrix resulted in consumption of leaking dissolved CO2 and reduced its mass along the leakage pathway. Consumption and retention of dissolved CO2 along the leakage pathway have important implications for analyzing the potential reduction of CO2 fluxes from storage reservoirs over large periods and long travel pathways.

Place, publisher, year, edition, pages
Elsevier, 2015. Vol. 42, 672-689 p.
Keyword [en]
CO2-saturated brine leakage, Reactive transport, Fracture, Matrix diffusion, Sorption, Calcite kinetic reaction
National Category
Geochemistry
Identifiers
URN: urn:nbn:se:kth:diva-180631DOI: 10.1016/j.ijggc.2015.09.001ISI: 000366947400061ScopusID: 2-s2.0-84945326226OAI: oai:DiVA.org:kth-180631DiVA: diva2:896549
Funder
StandUp
Note

QC 20160121

Available from: 2016-01-21 Created: 2016-01-19 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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