科研之友
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摘要
In the Norwegian North Sea, the Sleipner field produces gas with a high CO(2) content. For environmental reasons, since 1996, more than 11 Mt of this carbon dioxide (CO(2)) have been injected in the Utsira Sand saline aquifer located above the hydrocarbon reservoir. A series of seven 3D seismic surveys were recorded to monitor the CO(2) plume evolution. With this case study, time-lapse seismics have been shown to be successful in mapping the spread of CO(2) over the past decade and to ensure the integrity of the overburden.
Stratigraphic inversion of seismic data is currently used in the petroleum industry for quantitative reservoir characterization and enhanced oil recovery. Now it may also be used to evaluate the expansion of a CO(2) plume in an underground reservoir. The aim of this study is to estimate the P-wave impedances via a Bayesian model-based stratigraphic inversion.
We have focused our study on the 1994 vintage before CO(2) injection and the 2006 vintage carried out after a CO(2) injection of 8.4 Mt. In spite of some difficulties due to the lack of time-lapse well log data on the interest area, the full application of our inversion workflow allowed us to obtain, for the first time to our knowledge, 3D impedance cubes including the Utsira Sand. These results can be used to better characterize the spreading of CO(2) in a reservoir. With the post-stack inversion workflow applied to CO(2) storage, we point out the importance of the a priori model and the issue to obtain coherent results between sequential inversions of different seismic vintages. The stacking velocity workflow that yields the migration model and the a priori model, specific to each vintage, can induce a slight inconsistency in the results.
- 出版日期2011-1
