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| Titel |
Use of FFEC Logging for Long-term Monitoring of Regional Flow in Multi-layer Aquifer System |
| VerfasserIn |
Prabhakar Sharma, Chin-Fu Tsang, Auli Niemi |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250078208
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| Zusammenfassung |
| The flowing fluid electrical conductivity (FFEC) logging method has been successfully used
in deep boreholes to estimate the transmissivity, salinity of formation water, hydraulic head,
and regional flow rate of hydraulically conducting layers as a function of depth, and to do so
in much less time than conventional well logging methods. In this method, the
wellbore fluid electrical conductivity (FEC) is measured over depth for a series of time
periods under pumping condition, after replacement of wellbore water with deionized
water or water of salinity distinctly different from that of the formation. These
FEC profiles are analyzed by fitting to an one-dimensional advection-dispersion
equation. In this presentation, we modified the FFEC procedure to monitor the temporal
changes in regional flows in a deep formation with multiple conductive layers for
periods of months and years. Regional flows in the layers can vary, for instance,
due to changes in subsurface flow recharge or discharge rates. In the event of CO2
injection in the deep subsurface for geological storage of supercritical CO2, the
regional flow pattern of the storage formation will be disturbed and may change
with time as the low density and low viscosity CO2 enters more and more into the
conductive layers. The present study explores the possibility of using the FFEC
method for such a long-term monitoring of the flow velocity of formation water in an
observation well. We assume the conductive layers in the storage formation to have
different values of transmissivity. Results indicate that potential long-term temporal
changes in regional flow in the layers can be estimated at a monitoring well by
the FFEC method. Conditions for the applicability of this method are discussed. |
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