Summary
The storage of carbon dioxide (CO2) in saline aquifers is one of
the most promising options for Europe to reduce emissions of greenhouse gases
from power plants to the atmosphere and to mitigate global climate change. The
CO2SINK (CO2 Storage by Injection into a saline aquifer
at Ketzin) project is a research and development (R&D) project, mainly
supported by the European Commission, the German Federal Ministry of Education
and Research, and the German Federal Ministry of Economics and Technology,
targeted at developing an in-situ laboratory for CO2
storage.
The preparatory phase of the project involved a baseline geological-site
exploration and the drilling of one injection and two observation wells, as
well as the acquisition of a geophysical baseline and geochemical monitoring,
in Ketzin, located near Berlin. The target saline aquifer is the lithologically
heterogeneous Triassic Stuttgart formation, situated at approximately 630- to
710-m (2,070- to 2,330-ft) depth. A comprehensive borehole-logging program was
performed consisting of routine well logging complemented with an enhanced
logging program for one well that recorded nuclear-magnetic-resonance (NMR) and
borehole-resistivity images, to characterize the storage formation better. A
core analysis program carried out on reservoir rock and caprock included
measurements of helium porosity, nitrogen permeability, and brine permeability
at different pressure conditions.
The saline aquifer at Ketzin shows a variable porosity/permeability
distribution, which is related to grain size, facies variation, and rock
cementation with values in the range from 5 to > 35% and 0.02 to >
5,000 md for porosity and permeability, respectively. On the basis of core
analysis and logging data, an elemental log-analysis model for the target
formation was established for all three wells. In addition, permeability was
estimated using the Coates equation and compared with core data and NMR
log-derived permeability, which seems to provide meaningful permeability
estimates for the Ketzin reservoir. On the basis of the good core control that
guided the petrophysical well-log interpretation in the first two
CO2SINK wells, a porosity and permeability prediction by analogy for
the third well is appropriate and applicable. The availability of cores was
crucial for a sophisticated formation evaluation at borehole scale that
characterizes the real subsurface conditions.
© 2010. Society of Petroleum Engineers
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History
- Original manuscript received:
7 July 2008
- Meeting paper published:
20 October 2008
- Revised manuscript received:
27 March 2009
- Manuscript approved:
22 May 2009
- Published online:
11 March 2010
- Version of record:
20 April 2010