 |
| Titel |
Seismic and geoelectric monitoring of CCS - parameter studies in simplified and realistic scenarios |
| VerfasserIn |
Matthias Strahser, Said Attia al Hagrey, Wolfgang Rabbel |
| Konferenz |
EGU General Assembly 2011
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250048894
|
|
|
|
|
|
| Zusammenfassung |
| The multi-disciplinary research project “CO2-MoPa” (modeling and parametrization of CO2
storage in deep saline formations for dimension and risk analyses) deals with the
parametrization of virtual subsurface storage sites to characterize rock properties with
modeling of processes related to CCS in deep saline reservoirs. The geophysical task is to
estimate the sensitivity and the resolution of reflection seismic and geoelectrical time-lapses
in order to determine the propagation of CO2 within the sediments and the development of
the CO2 reservoir. Compared with seismics, electric resistivity tomography (ERT) in
boreholes has a lower resolution, but its permanent installation and continuous monitoring
can make it a complement.
In the first part of this study, we use simplified models to investigate the effects of
selected parameters or their combinations on seismic and geoelectric properties and how this
affects monitoring possibilities with reflection seismics and ERT (in boreholes).
In the second part, we apply the acquired experiences on a realistic subsurface
scenario in the North German Basin (Wagrien, Eastern Holstein). We obtain the
necessary parameters from other CO2-MoPa sub-projects (e.g. geochemistry, geology)
and from literature. The study focuses on effects of parameters related to depths,
petrophysics, plume forms, dimensions and saturations, reservoir salinity, as well as on data
acquisition, processing and inversions. Both methods show stronger effects with
increasing brine salinity, CO2 reservoir thickness, porosity and CO2 saturation in
the pore fluid. They have a pronounced depth dependence due to the pressure and
temperature dependence of the velocities, densities and resistivities of the sequestration
targets (host rock, brine, and CO2). While the lateral extent of a thin CO2 reservoir
can be determined rather accurately with seismics, the reflections from its top and
bottom interfere with each other, making it difficult to identify the exact vertical
dimensions of the reservoir. This is especially true in the more realistic scenario with
several interfering reflectors. In BRT, the resulting resistivity resolution and anomaly
magnitudes are inversely proportional to the salinity and temperatures and directly
proportional to CO2 saturation, dimensions, and aspect ratio. The sensitivity of
the seismic method to CO2 saturation changes is most pronounced for low CO2
concentrations while the geoelectric method has a higher sensitivity to concentration
changes at high concentrations. A combination of the two geophysical monitoring
techniques can thus be advantageous, especially in the estimation of the mass of the CO2
anomaly.
Acknowledgments
This study is funded by the German Federal Ministry of Education and Research
(BMBF), EnBW Energie Baden-Württemberg AG, E.ON Energie AG, E.ON Gas Storage
AG, RWE Dea AG, Vattenfall Europe Technology Research GmbH, Wintershall Holding AG
and Stadtwerke Kiel AG as part of the CO2-MoPa joint project in the framework of the
Special Program GEOTECHNOLOGIEN. |
|
|
|
|
|
|