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Abstract

Geophysical monitoring at the CO2 pilot storage Ketzin comprises time-lapse seismic and geoelectric (ERT) measurements. Both types of measurements are known to image geological structures differently, in particular for a variable saturation of CO2. We present a combination of both methods by means of a structural constrained inversion approach. Structural constraints are implemented in the geoelectric inversion by a local regularization. This allows model parameters to behave discontinuously across prominent geological boundaries. A tetrahedral finite-element parametrization is used to closely follow geometric a priori structures interpreted from seismic reflection data. Thus, seismics and geoelectrics are arranged in a sequential workflow which is based on a structural similarity. Practical application is performed on the Ketzin datasets which comprise repeated 3D seismic surveys, as well as repeated surface-downhole geoelectric surveys, providing different illumination/coverage and time-lapse signals. However, application of a local regularization for the caprock-reservoir boundary yields a more consistent image and reduces some of the ill-posedness in the ERT inversion. We compare the result with that of an unconstrained inversion and discuss its potential for CO2 migration imaging.

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/content/papers/10.3997/2214-4609.20148254
2012-06-04
2024-03-29
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http://instance.metastore.ingenta.com/content/papers/10.3997/2214-4609.20148254
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