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| Titel |
Analysis of Multilevel Pressure Transient Data at the Illinois Basin - Decatur Project |
| VerfasserIn |
Christin W. Strandli, Edward Mehnert, Sally M. Benson |
| 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 |
250099868
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| Publikation (Nr.) |
 EGU/EGU2014-15706.pdf |
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| Zusammenfassung |
| Based on numerical studies in TOUH2/ECO2N and analyses of multilevel (depth-discrete)
pressure transient data at the Illinois Basin - Decatur Project (IBDP), this study
demonstrates methods for using multilevel pressure transient data as a means to further
characterize the storage formation and for monitoring carbon dioxide (CO2) and
displaced brine migration. By incorporating multilevel pressure monitoring into the
monitoring program, additional information is available that can be used to minimize and
manage potential risk associated with CO2 and displaced brine migration to shallower
depths.
Previously, we used simulated pressure data from numerical studies in TOUGH2/ECO2N
to identify diagnostics for reservoir structure (layering and anisotropy) and CO2
plume migration. In particular, we found that important insights can be obtained
by: 1) normalizing the pressure buildups to the pressure buildup at the depth of
injection, and 2) calculating vertical pressure gradients normalized to the initial
hydrostatic pressure gradient. Soon after the start of injection, pressure buildups
normalized to the pressure buildup at the depth of injection and vertical pressure
gradients normalized to the initial hydrostatic pressure gradient are diagnostic of
reservoir structure, and over time provide information on the height of the CO2
plume.
In this study, the identified diagnostics are applied to the pressure transient data at the
IBDP, where the Westbay* multilevel groundwater characterization and monitoring system
was installed in a deep in-zone verification well (2,000 m) to measure the pressure buildup at
multiple depths within the Mt. Simon storage reservoir and above the Eau Claire Formation
(primary seal) during CO2 injection. Using the diagnostic tools, we are able to
correctly identify the height of the CO2 plume. Specifically, the multilevel pressure
transient data alone indicate that the CO2 plume remains largely confined to the 23-24
m interval into which it is being injected, and there is no indication of buoyancy
driven flow towards the shallower portions of the Mt. Simon. This prediction is
confirmed by RSTPro* reservoir saturation tool logs and sampling carried out by IBDP
staff.
In addition, a multilayered, radially symmetric model with TOUGH2/ECO2N is
used to history match the pressure buildup at the injection well and the verification
well. Our overall excellent match with the pressure transient data from the IBDP
demonstrates that by history matching multilevel pressure transient data, a hydrogeological
model can be developed that in turn can be used to predict future CO2 migration.
Uncertainty remains with regard to the lateral extent of low-permeability layers
and their ability to provide capillary barriers to the upward migrating CO2 across
larger areas. Because pressure data are non-unique, rigorous sensitivity studies are
conducted and other geologic model scenarios are also considered. Overall, the number
and placement of monitoring zones will affect the vertical resolution of reservoir
heterogeneity and the ability to constrain a hydrogeological model with pressure history
matching.
Funding for this research was provided by the United States Environmental
Protection Agency (EPA) – Science to Achieve Results (STAR) program, Grant
R834383.
*Mark of Schlumberger |
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