Title
CO2 dissolution and its impact on reservoir pressure behavior
Author
Peters, E.
Egberts, P.J.P.
Loeve, D.
Hofstee, C.
Publication year
2015
Abstract
Geological storage of CO2 in large, saline aquifers needs to be monitored for safety purposes. In particular the observation of the pressure behavior of a storage site is relevant for the indication of CO2 leakage. However, interpretation of observed pressure is not straightforward in these systems, due to the large number of natural processes that affects the pressure. These processes include pressure dissipation across aquifer boundaries for which both location and transmissibility are uncertain, pressure dissipation in low-permeable deposits surrounding the aquifer, dissolution of CO2 into the brine and chemical reactions. In this paper we will focus on the aquifer pressure effects of dissolution of CO2 in brine which can be significantly enhanced by density-driven convective mixing. The convective mixing occurs because the density of brine increases due to the dissolution of CO2, creating an unstable layer of dense brine below the CO2 plume. This layer may induce vertical, density-driven convective flow in so-called fingers. We have studied the effect of convectively-enhanced CO2 dissolution on the pressure in a CO2 storage site for 50 years using a volume balance model. This showed that only for reservoirs with very high permeability (>500mD in vertical direction) and a thin CO2 layer (<2-3m), the pressure reduction due to CO2 dissolution enhanced by convective mixing is important (>0.05bar/yr). For most examples simulated here, the effect of CO2 dissolution on the pressure was minor (<0.02bar/yr or <0.2% of the pressure increase due to CO2 injection per year). © 2015 Elsevier Ltd.
Subject
Geo
PG - Petroleum Geosciences
ELSS - Earth, Life and Social Sciences
Geological Survey Netherlands
Geosciences
2015 Energy
CO2 storage
Monitoring
Aquifer
Volume balance approach
CO2 dissolution
Convective mixing
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http://resolver.tudelft.nl/uuid:601f9dcf-4c47-470d-9500-b771e45d8024
DOI
https://doi.org/10.1016/j.ijggc.2015.10.016
TNO identifier
529728
Publisher
Elsevier Ltd
ISSN
1750-5836
Source
International Journal of Greenhouse Gas Control, 43, 115-123
Document type
article