CO2 on the move

Geophysicists working within IFPEN's Geology-Geochemistry-Geophysics Division have just achieved a first: adapting interpretation techniques developed for the characterization of oil fields to the geological CO₂ storage context.

Noalwenn Sallée Geology-Geochemistry-Geophysics Division noalwenn.sallee@ifpen.fr

It is essential to monitor the evolution of CO₂ injected into a geological reservoir to ensure that the storage site remains intact over time and to fine-tune simulation models.

Among the various geophysical methods examined repetitive seismic data are emerging today as the most effective method of meeting these two objectives. However, this methodis dependent on being able to interpret seismic property variations in underground environments due to the injection of CO₂ between two data acquisitions separated over time.

Geophysicists working within IFPEN's Geology-Geochemistry-Geophysics Division have just achieved a first, adapting interpretation techniques developed for the characterization of oil fields to the geological CO₂ storage context. As part of the European FP6 project, CO₂ReMoVe, these techniques have been applied to seismic data recorded at the Sleipner site (North Sea - Norway) during surveys conducted in 1994 and 2006 (before and after 10 years of CO₂ injection). The seismic impedance variations obtained enable monitoring of the 3D evolution of the CO₂ plume within the host saline aquifer.

The results obtained have been analyzed in order to quantify the CO₂ stored in the aquifer. Comparison of these data with reservoir simulations will help reinforce predictions relative to storage site behavior over several centuries. More broadly, the experience acquired thanks to the development and deployment of these new technologies on the first sites will enable recommendations to be drawn up relative to the management of geological CO₂ storage sites.

3D view of the distribution of P wave impedance obtained following seismic inversion of data acquired in 2006. CO₂ is identified by lower impedance values (blue and green colors) inside the reservoir (as per Clochard et al. First Break 2010).

Publications

• T. Tonellot, M.-L. Bernard and V. Clochard, 2010. Method of joint inversion of seismic data represented on different time scales, US Patent 2010/0004870 A1.
• N. Delépine, V. Clochard, K. Labat, P. Ricarte, 2010. Post- stack stratigraphic inversion workflow applied to carbon dioxide storage: application to the saline aquifer of Sleipner field, accepted in Geophysical Prospecting. DOI: 10.1111/j.1365-2478.2010.00905.x
• N. Dubos-Sallée and P. Rasolofosaon, 2011. Estimation of permeability anisotropy using seismic inversion for the CO₂ geological storage site of Sleipner (North Sea), Geophysics, vol 76 (3), B1–B7
  

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