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| Titel |
Merging single-well and inter-well tracer tests into one forced-gradient dipole test, at the Heletz site within the MUSTANG project |
| VerfasserIn |
Horst Behrens, Julia Ghergut, Jac Bensabat, Auli Niemi, Tobias Licha, Thomas Ptak, Martin Sauter |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250090213
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| Publikation (Nr.) |
 EGU/EGU2014-4434.pdf |
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| Zusammenfassung |
| The Heletz site[1] in Israel was chosen for conducting a CO2 transport experiment within the
MUSTANG project[2], whose aim is to demonstrate and validate leading-edge techniques for
CCS site characterization, process monitoring and risk assessment.
The major CO2 injection experiment at Heletz was supposed to be preceded and
accompanied by a sequence of single-well ‘push-then-pull’ (SW) and inter-well (IW)
tracer tests, aimed at characterizing transport properties of the storage formation, in
accordance to a number of general and specific principles[3],[4]. – Instead of the rather
luxurious {SW1, IW1, SW2, IW2} test sequence described in our previous work[5], we
now propose a drastically economized tracer test concept, which lets the sampling
stages of SW and IW tests merge into a single fluid production stage, and relies
on a forced-gradient dipole flow field at any time of the overall test. Besides cost
reduction, this economized design also improves on operational aspects, as well as on
issues of parameter ambiguity and of scale disparity between SW and IW flow
fields:
(i) the new design renders SW test results more representative for the aquifer sector
(‘angle’) actually interrogated by the IW dipole test;
(ii) the new design saves time and costs on the SW test (fluid sampling for SW ‘pull’ now
being conducted simultaneously with IW-related sampling and monitoring), while allowing
for a considerably longer duration of SW ‘pull’ signals than had originally been intended,
whose late-time tailings help improve the quantification of non-advective processes and
parameters, which are of great relevance to mid- and long-term trapping mechanisms
(‘residual trapping’, ‘mineral trapping’);
(iii) the quasi-simultaneous execution of fluid injection/production for the IW and SW
tests considerably reduces the overall hydraulic imbalance that was originally associated with
the SW test, thus preventing formation damage and supporting hydrogeomechanical
stability;
(iv) the new design reduces the imbalance between injected and produced fluid volumes
at any time to a minimum, thus eliminating the need for large-capacity tanks (and water
supply) to provide ‘push’ fluid for injection and to store ‘pull’ fluid during production within
the SW test (saving on costs again).
Advantages and drawbacks of this modified tracer test concept w.r. to parameter
sensitivity and scale representativity are further analyzed by means of numerical simulations
of tracer transport in the layered Heletz aquifer (using FEOW) alongside with closed-form
approximations to tracer signals.
References:
[1] www.co2mustang.eu/Heletz.aspx
[2] www.co2mustang.eu/
[3] Behrens H, Ghergut I, Sauter M (2010) Tracer properties, and tracer test results, part 3:
modification to Shook’s flow-storage diagram. Stanford Geothermal Prog Tech Reports,
SGP-TR-188
[4] Ghergut I, Behrens H, Maier F, Karmakar S, Sauter M (2011) A note on ‘heat
exchange areas’ as a target parameter for tracer SWIW tests. Stanford Geothermal Prog Tech
Reports, SGP-TR-191
[5] presentations.copernicus.org/EGU2012-13549_presentation.pdf
and presentations.copernicus.org/EGU2013-3683_presentation.pdf
Acknowledgements: Heletz hydrostratigraphy data were provided by the MUSTANG
project teams[1],[2], this project being funded by the EU under FP7 (grant no.227286). Tracer
transport modeling for IW and SW tests in layered reservoirs was conducted within the
‘gebo’ project (‘Geothermal Energy and High-Performance Drilling’, www.gebo-nds.de),
funded by the Lower-Saxonian government and by Baker Hughes (Celle), Germany. |
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