Title
Observed CO2-induced reactivity in werkendam gas field, the Dutch storage analogue
Author
Koenen, M.
Wasch, L.
Waldmann, S.
van der Gijp, S.
Contributor
Dixon, T. (editor)
Twinning, S. (editor)
Herzog, H. (editor)
Publication year
2014
Abstract
Natural CO2 fields provide important insights in the long-term geochemical behaviour of CO2 in a reservoir and the potential of permanent trapping in carbonate minerals. The Werkendam gas field in The Netherlands, discovered during gas exploration activities in 1991, contains >70% CO2. Core samples were selected from the Werkendam natural analogue (WED) as well as from the nearby Barendrecht-Ziedewij (BRTZ) and Waalwijk-Noord (WWN) CH4-bearing reservoirs. The three gas reservoirs are all Triassic Bunter sandstones, with BRTZ and WWN containing respectively 0.8% and 1.4% CO2. Mineralogical and petrographic analyses were performed to unravel the diagenetic evolution of each field for comparison. Early diagenetic mineral reactions were similar for the three field. Minor differences are attributed to variation in primary mineralogy and the K+/H+ ratio of the formation water. The late stage mineral reactions that are observed in WED which are absent in BRTZ and WWN were interpreted to be induced by the influx of CO2. These include the (additional) dissolution of K-feldspar and anhydrite, and the precipitation of Mg-rich siderite, quartz and barite. Even though carbon isotope analysis could not confirm (but also not exclude) this, petrographic analysis gave strong indications for the precipitation of siderite in WED as a result of the high CO2 partial pressure. The estimated amount of carbon trapping in siderite is 20% to 58% of the total CO2. Barite precipitation was probably the result of K-feldspar and anhydrite dissolution, since barium is a common impurity in K-feldspar. In the overall reaction between the sandstone and carbonized brine, several unknowns remain. A sink for calcium, potassium and aluminium from anhydrite and K-feldspar dissolution was not observed in the samples from WED. In addition, potential sources of magnesium and iron for Mg-rich siderite could not be deduced from the comparison of the fields. Possibly, these sinks and sources can be found in the clay-rich intervals within the sandstone reservoir. Future research should investigate the effect of heterogeneity within storage complexes on mineral trapping.
Subject
Earth / Environmental
SGE - Sustainable Geo Energy
ELSS - Earth, Life and Social Sciences
Geological Survey Netherlands
Geosciences
Energy
CO2 storage
Long-term mineral reactions
Mineral trapping
Natural analogue
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http://resolver.tudelft.nl/uuid:ac842716-de89-4fd6-bd31-f4d318aa4f01
TNO identifier
523256
Publisher
Elsevier, Amsterdam
ISSN
1876-6102
Source
Energy Procedia, 63, 2985-2993
Document type
conference paper