Geoelectrical methods for monitoring geological CO₂ storage: First results from cross-hole and surface–downhole measurements from the CO₂SINK test site at Ketzin (Germany)

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• 作者：Dana Kiessling ; Cornelia Schmidt-Hattenberger ; Hartmut Schuett ; Frank Schilling ; Kay Krueger ; Birgit Schoebel ; Erik Danckwardt ; Juliane Kummerow ; the CO₂SINK Group
• 关键词：Electrical resistivity tomography (ERT) ; Geoelectric monitoring ; CO₂ storage ; Field data ; Buried electrodes
• 刊名：International Journal of Greenhouse Gas Control
• 出版年：2010
• 出版时间：September 2010
• 年：2010
• 卷：4
• 期：5
• 页码：816-826
• 全文大小：1661 K

文摘

The feasibility of monitoring CO₂ migration in a saline aquifer at a depth of about 650 m with cross-hole and surface–downhole electrical resistivity tomography (ERT) is investigated at the CO₂SINK test site close to Ketzin (Germany). The permanent vertical electrical resistivity array (VERA) consists of 45 electrodes (15 in the injection well Ktzi201 and 15 in each of the two observation wells Ktzi200 and Ktzi202), successfully placed on the electrically insulated casings, in the depth range of about 590–740 m with a spacing of about 10 m. The three Ketzin wells are arranged as perpendicular triangle with distances of 50 and 100 m.

First synthetic modelling studies indicate an increase of the electrical resistivity of about 200 % caused by CO₂ injection, corresponding to a bulk CO₂ saturation of 50 % , which is in good agreement with laboratory studies. Finite difference inversion of field data delivers three-dimensional resistivity distributions between the wells which are consistent with the reservoir modelling studies.

To increase the limited observation area provided by the cross-hole measurements, additional surface–downhole measurements were deployed. A main CO₂ migration in SE–NW direction is deduced from surface to downhole resistivity experiments.

The first cross-hole time-lapse results show that the resolution and the coverage of the electrode array in the Ketzin setting are sufficient to resolve the expected resistivity changes on the characteristic length scale of the electrode array. Significant resistivity changes could be measured, however, detailed information on the CO₂ plume could not be resolved yet by VERA under the existing geological circumstances.