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| Titel |
Subsurface characterisation and modeling of a CO2 test site in south Scania, Sweden, with special emphasis on the treatment of hydrogeological heterogeneity |
| VerfasserIn |
Kristina Rasmusson, Auli Niemi, Mikael Erlström |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250054217
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| Zusammenfassung |
| The south Scania site is one of the five test sites included in the MUSTANG project (EU FP7
programme) with an objective to understand - by means of experimental and simulation
studies - the spreading and trapping of injected CO2 in different type saline formations. The
geological setting of the site is an example of a typical multilayered sequence commonly
found in sedimentary basins all over the world. It is analyzed here as an example of such
sequence of primary and secondary traps and seal units. Particular emphasis is given for the
characterization and quantification of the geological heterogeneity, in terms of what
can be described in deterministic terms and where a stochastic representation is
needed.
For constructing the conceptual model, detailed hydrogeological and hydrogeochemical
data is available in one deep well originally drilled for geothermal investigations, including
an extensive hydrogeological testing programme. In addition, comprehensive data sets and
analyses exist in 15 adjacent wells, allow definition of the characteristics of different
lithological units and boundary layers with some confidence. The geology is dominated by a
relatively thick (1200–1600 m) sequence of Upper Cretaceous strata, overlying a 400–600 m
thick Lower Cretaceous, Jurassic and Triassic sequence of claystone and sandstone layers.
Eight lithologic units have been mapped and characterised, the primary trap aquifer for this
study being about 10 m thick sandstone and secondary traps having thicknesses between 10
and 50 metres, with lower overall permeabilities than the primary target. The primary seal
consist of a several hundred meters thick limestone and the intermediate seals of claystone
and mudstone. The lateral correlations of the layers between wells are based on
lithological descriptions of cuttings, biostratigraphical analyses and geophysical well log
correlation.
One of the challenges for modeling the spreading of injected CO2 is to understand and to
be able to quantify the characteristics of the horizontal heterogeneity and continuity
of the layers between the boreholes. For this purpose, both a deterministic and a
probabilistic/stochastic approach are used here to describe 1) the distribution of the
depositional settings and 2) the properties (heterogeneity) within the units, in particular in
terms of the distribution of the permeability values. Importance of the choice of the approach
is discussed based on preliminary model simulations of CO2 injection using the various
assumptions. |
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