| 1. |
- Zhang, Fengjiao, 1981-, et al.
(författare)
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Application of seismic waveform tomography to monitoring of CO2 injection : modeling and a real data example from the Ketzin site, Germany
- 2013
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Ingår i: Geophysical Prospecting. - : Wiley-Blackwell. - 0016-8025 .- 1365-2478. ; 61:Suppl.s1, s. 284-299
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Tidskriftsartikel (refereegranskat)abstract
- Seismic monitoring of the injected carbon dioxide (CO2) distribution at depth is an important issue in the geological storage of CO2. To help monitor changes in the subsurface during CO2 injection a series of 2D seismic surveys were acquired within the framework of the CO2SINK and CO2MAN projects at Ketzin, Germany at different stages of the injection process. Here we investigate using seismic waveform tomography as a qualitative tool for time-lapse seismic monitoring given the constraints of the limited maximum offsets of the 2D seismic data. Prior to applying the inversion to the real data we first made a number of benchmark tests on synthetic data using a similar geometry as in the real data. Results from the synthetic benchmark tests show that it is difficult to recover the true value of the velocity anomaly due to the injection, but that it is possible to qualitatively locate the distribution of the injected CO2. After the synthetic studies, we applied seismic waveform tomography on the real time-lapse data from the Ketzin site along with conventional time-lapse processing. Both methods show a similar qualitative distribution of the injected CO2 and agree well with expectations based upon more extensive 3D time-lapse monitoring in the area.
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| 2. |
- Bastani, Mehrdad, 1960-, et al.
(författare)
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3D magnetic susceptibility model of a deep iron-oxide apatite-bearing orebody incorporating borehole data in Blötberget, Sweden
- 2019
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Konferensbidrag (refereegranskat)abstract
- We have processed and modelled in 3D available airborne magnetic data flown over the Blötberget iron-oxide deposit in central Sweden. 3D magnetic susceptibility models were then compared to the existing borehole information, downhole logging data and ground geological observations. Use of such information in the 3D inversion of the magnetic field data in the form of a reference model has considerably improved the 3D model in resolving the deeper parts of the iron-oxide orebody as well as the geometry of nearby geological structures. Unconstrained inversion results, however, do not resolve the true dip and depth extension of the iron-oxide orebody.
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| 3. |
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| 4. |
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| 5. |
- Bergmann, Peter, et al.
(författare)
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Review on geophysical monitoring of CO2 injection at Ketzin, Germany
- 2016
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Ingår i: Journal of Petroleum Science and Engineering. - : Elsevier BV. - 0920-4105. ; 139, s. 112-136
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Tidskriftsartikel (refereegranskat)abstract
- Geophysical monitoring activities were an important component of the CO2 injection program at the Ketzin site, Germany. Here we report on the seismic and electrical resistivity tomography (ERT) measurements performed during the period of the site development and CO2 injection. Details on the site geology, the history of the CO2 injection operation, and petrophysical models relevant for the interpretation of the geophysical data are presented. The seismic measurements comprise 2D and 3D surface seismic surveys, vertical seismic profilings, and crosshole measurements. Apart from the measurements, results from advanced processing methods, such as impedance inversion and full-waveform inversion are also presented. In addition, results from crosshole ERT and surface-downhole ERT are presented. If operational efforts are taken into consideration we conclude that a combination of several geophysical methods is preferable given the demands of a spatiotemporally comprehensive monitoring program. We base this conclusion on that the different imaging characteristics and petrophysical sensitivities of different methods can complement each other. An important finding is, based on signal quality and reduced operational costs, that the use of permanent installations is promising. Generally, specific monitoring layouts will depend on site-specific characteristics, such as reservoir depth, availability of wells, petrophysical characteristics, and accessibility of surface locations. Given the comprehensive range of methods applied, the reported results are not only relevant to the operation of CO2 storage sites, but are also of interest to other monitoring projects dealing with fluid injection or production.
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| 8. |
- Huang, Fei, 1987-, et al.
(författare)
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Application of seismic complex decomposition on thin layer detection of the CO2 plume at Ketzin, Germany
- 2015
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Konferensbidrag (refereegranskat)abstract
- The seismic complex decomposition technique is a spectral decomposition method using inversion strategies to decompose a seismic trace into its constituent frequencies and corresponding complex coefficients. This method has high time-frequency resolution and it is not necessary to select a signal window in comparison to conventional spectral decomposition methods. The thickness of the reservoir at the Ketzin pilot site is relatively thin, making it difficult to resolve seismically due to the band-limited seismic spectrum. This study presents an application of seismic complex decomposition to the time-lapse 3D seismic datasets at the Ketzin pilot site for estimating the temporal thickness of the injected CO2 within the thin reservoir via frequency tuning. Quantitative analysis for CO2 thickness and mass is investigated. Comparison between the real recorded data and the estimates shows that our results are reliable in assessing the amount of the CO2 in the plume at the Ketzin pilot site.
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| 9. |
- Huang, Fei, et al.
(författare)
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Feasibility of utilizing wavelet phase to map the CO2 plume at the Ketzin pilot site, Germany
- 2017
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Ingår i: Geophysical Prospecting. - : Wiley. - 0016-8025 .- 1365-2478. ; 65:2, s. 523-543
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Tidskriftsartikel (refereegranskat)abstract
- Spectral decomposition is a powerful tool that can provide geological details dependent upon discrete frequencies. Complex spectral decomposition using inversion strategies differs from conventional spectral decomposition methods in that it produces not only frequency information but also wavelet phase information. This method was applied to a time‐lapse three‐dimensional seismic dataset in order to test the feasibility of using wavelet phase changes to detect and map injected carbon dioxide within the reservoir at the Ketzin carbon dioxide storage site, Germany. Simplified zero‐offset forward modelling was used to help verify the effectiveness of this technique and to better understand the wavelet phase response from the highly heterogeneous storage reservoir and carbon dioxide plume. Ambient noise and signal‐to‐noise ratios were calculated from the raw data to determine the extracted wavelet phase. Strong noise caused by rainfall and the assumed spatial distribution of sandstone channels in the reservoir could be correlated with phase anomalies. Qualitative and quantitative results indicate that the wavelet phase extracted by the complex spectral decomposition technique has great potential as a practical and feasible tool for carbon dioxide detection at the Ketzin pilot site.
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| 10. |
- Huang, Fei, 1987-, et al.
(författare)
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Preliminary Seismic Time-lapse Results from the First Post-injection Survey at the Ketzin Pilot Site
- 2016
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Konferensbidrag (refereegranskat)abstract
- Since the CO2SINK project start in April 2004, different methods involving seismics, geoelectrics andpressure-temperature monitoring have been applied at the Ketzin pilot site to map geological structuresand assess CO2 distribution and movement. One 3D baseline seismic survey prior to CO2 injection andtwo 3D repeat seismic surveys during CO2 injection have proven that the 3D time-lapse surface seismicmethod is an effective tool for providing good quality images of the CO2 plume. In the autumn of 2015, athird 3D repeat seismic survey, serving as the first post-injection survey, was acquired. The preliminaryresults show that the predominant westward trend of the CO2 migration is in agreement with the previousresults. No CO2 migration upwards through the caprock was detected. The decrease in the size of CO2plume may be related to ongoing dissolution into the saline formation water.
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