| 1. |
- Bergmann, Peter, et al.
(author)
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Time-lapse difference static correction using prestack crosscorrelations : 4D seismic image enhancement case from Ketzin
- 2014
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In: Geophysics. - : Society of Exploration Geophysicists. - 0016-8033 .- 1942-2156. ; 79:6, s. B243-B252
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Journal article (peer-reviewed)abstract
- A method for static correction of time-lapse differences in reflection arrival times of time-lapse prestack seismic data is presented. These arrival-time differences are typically caused by changes in the near-surface velocities between the acquisitions and had a detrimental impact on time-lapse seismic imaging. Trace-to-trace time shifts of the data sets from different vintages are determined by crosscorrelations. The time shifts are decomposed in a surface-consistent manner, which yields static corrections that tie the repeat data to the baseline data. Hence, this approach implies that new refraction static corrections for the repeat data sets are unnecessary. The approach is demonstrated on a 4D seismic data set from the Ketzin CO2 pilot storage site, Germany, and is compared with the result of an initial processing that was based on separate refraction static corrections. It is shown that the time-lapse difference static correction approach reduces 4D noise more effectively than separate refraction static corrections and is significantly less labor intensive.
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| 2. |
- Ivandic, Monika, et al.
(author)
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Geophysical monitoring at the Ketzin pilot site for CO2 storage : New insights into the plume evolution
- 2015
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In: International Journal of Greenhouse Gas Control. - : Elsevier BV. - 1750-5836 .- 1878-0148. ; 32, s. 90-105
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Journal article (peer-reviewed)abstract
- To date, 3D time-lapse seismic monitoring at the Ketzin CO2 storage pilot site comprised a baseline survey conducted in 2005 and two repeat surveys conducted in 2009 and 2012. At the time of the first repeat survey (22-25 kt of CO2), the CO2 plume was found to be concentrated around the injection well with a maximum lateral extent of approximately 300-400 m and a thickness of 5-20m. Data from the 2012 survey (61 kt of CO2), show further growth and migration of the amplitude anomaly interpreted to be induced by the CO2 injection. The anomaly is similar in shape to that obtained from the 2009 survey, but significantly stronger and larger by similar to 150m in the N-S direction and by similar to 200m in the E-W direction. In agreement with the 2009 survey, the new data show a westward propagation of the plume, a trend governed by the complex structure of the reservoir. No evidence of systematic changes in the seismic signature within the overburden is observed. A quantitative assessment of the plume reveals a 15% discrepancy with the injected amount, which could be attributed to the ongoing dissolution processes. However, the estimated quantity also contains significant uncertainty.
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| 3. |
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| 4. |
- Ivandic, Monika, et al.
(author)
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Monitoring CO2 saturation using time-lapse amplitude versus offset analysis of 3D seismic data from the Ketzin CO2 storage pilot site, Germany
- 2018
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In: Geophysical Prospecting. - : WILEY. - 0016-8025 .- 1365-2478. ; 66:8, s. 1568-1585
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Journal article (peer-reviewed)abstract
- The injection of CO2 at the Ketzin pilot site commenced in June 2008 and was terminated in August 2013 after 67 kT had been injected into a saline formation at a depth of 630-650 m. As part of the site monitoring program, four 3D surface seismic surveys have been acquired to date, one baseline and three repeats, of which two were conducted during the injection period, and one during the post-injection phase. The surveys have provided the most comprehensive images of the spreading CO2 plume within the reservoir layer. Both petrophysical experiments on core samples from the Ketzin reservoir and spectral decomposition of the 3D time-lapse seismic data show that the reservoir pore pressure change due to CO2 injection has a rather minor impact on the seismic amplitudes. Therefore, the observed amplitude anomaly is interpreted to be mainly due to CO2 saturation. In this study, amplitude versus offset analysis has been applied to investigate the amplitude versus offset response from the top of the sandstone reservoir during the injection and post-injection phases, and utilize it to obtain a more quantitative assessment of the CO2 gaseous saturation changes. Based on the amplitude versus offset modelling, a prominent decrease in the intercept values imaged at the top of the reservoir around the injection well is indeed associated solely with the CO2 saturation increase. Any change in the gradient values, which would, in case it was positive, be the only signature induced by the reservoir pressure variations, has not been observed. The amplitude versus offset intercept change is, therefore, entirely ascribed to CO2 saturation and used for its quantitative assessment. The estimated CO2 saturation values around the injection area in the range of 40%-60% are similar to those obtained earlier from pulsed neutron-gamma logging. The highest values of 80% are found in the second seismic repeat in close vicinity to the injection and observation wells.
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| 5. |
- Ivandic, Monika, et al.
(author)
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Time-lapse AVO Analysis of 3D Surface Seismic Data Sets from the Ketzin CO2 Storage Pilot Site, Germany
- 2015
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Conference paper (peer-reviewed)abstract
- Time–lapse 3D surface seismic monitoring at the Ketzin CO2 storage pilot site has provided time–lapse images of the spreading plume, which has been interpreted as being caused by fluid saturation changes only. The integration of seismic AVO/AVA modeling and petrophysical experiments on core samples from the Ketzin reservoir support the interpretation of the field data by demonstrating that pressure has a rather minor impact on the seismic amplitudes at the Ketzin site. In this study Amplitude Variation with Offset (AVO) analysis has been applied to the baseline and the latest 3D repeat data set to investigate the real AVO response from the top of the sandstone reservoir after the injection of ~ 61 kT of CO2. The results show a good agreement with the modeling results, indicating that CO2 saturation effect dominates the time–lapse seismic signature.
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| 6. |
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| 7. |
- Ivanova, Alexandra, et al.
(author)
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Monitoring and volumetric estimation of injected CO2 using 4D seismic, petrophysical data, core measurements and well logging : a case study at Ketzin, Germany
- 2012
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In: Geophysical Prospecting. - : Wiley. - 0016-8025 .- 1365-2478. ; 60:5, s. 957-973
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Journal article (peer-reviewed)abstract
- More than 50 000 tons of CO2 have been injected at Ketzin into the Stuttgart Formation, a saline aquifer, at approximately 620 m depth, as of summer 2011. We present here results from the 1st repeat 3D seismic survey that was performed at the site in autumn 2009, after about 22 000 tons of CO2 had been injected. We show here that rather complex time-lapse signatures of this CO2 can be clearly observed within a radius of about 300 m from the injection well. The highly irregular amplitude response within this radius is attributed to the heterogeneity of the injection reservoir. Time delays to a reflection below the injection level are also observed. Petrophysical measurements on core samples and geophysical logging of CO2 saturation levels allow an estimate of the total amount of CO2 visible in the seismic data to be made. These estimates are somewhat lower than the actual amount of CO2 injected at the time of the survey and they are dependent upon the choice of a number of parameters. In spite of some uncertainty, the close agreement between the amount injected and the amount observed is encouraging for quantitative monitoring of a CO2 storage site using seismic methods.
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| 8. |
- Juhlin, Christopher, 1956-, et al.
(author)
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Seismic and Electrical Resistivity Tomography 3D Monitoring at the Ketzin Pilot Storage Site in Germany
- 2019
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In: Geophysics and Geosequestration. - : Cambridge University Press. - 9781316480724
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Book chapter (peer-reviewed)abstract
- Geosequestration involves the deep geological storage of carbon dioxide from major industrial sources, providing a potential solution for reducing the rate of increase of atmospheric concentrations of carbon dioxide and mitigating climate change. This volume provides an overview of the major geophysical techniques and analysis methods for monitoring the movement and predictability of carbon dioxide plumes underground. Comprising chapters from eminent researchers, the book is illustrated with practical examples and case studies of active projects and government initiatives, and discusses their successes and remaining challenges. A key case study from Norway demonstrates how governments and other stake-holders could estimate storage capacity and design storage projects that meet the requirements of regulatory authorities. Presenting reasons for embracing geosequestration, technical best practice for carbon management, and outlooks for the future, this volume provides a key reference for academic researchers, industry practitioners and graduate students looking to gain insight into subsurface carbon management.
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| 9. |
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| 10. |
- Lueth, Stefan, et al.
(author)
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4D Seismic Monitoring of CO2 Storage During Injection and Post-closure at the Ketzin Pilot Site
- 2017
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In: Energy Procedia. - : Elsevier. - 1876-6102. ; 114, s. 5761-5767
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Journal article (peer-reviewed)abstract
- At the Ketzin pilot site for geological CO2 storage, about 67,000 tons of CO2 were injected during the period June 2008 – August 2013. Since August 2013, the site is in its post-closure phase. Before and during the injection phase, a comprehensive monitoring programme was established. In the early post-injection phase, a majority of the monitoring activities have continued. The stepwise abandonment of the pilot site, which is planned to be accomplished in 2018, marks also the termination of most monitoring activities. Four 3D seismic surveys were acquired between 2005 and 2015 for characterizing the reservoir structure and its overburden and for monitoring the propagation of the injected CO2 in the storage formation. The first and second repeat surveys revealed the lateral extension of the CO2 plume after injecting 22 and 61 ktons, respectively. In autumn 2015, the third 3D repeat seismic survey, serving as the first post-injection survey, was acquired. The survey was acquired using the same acquisition geometry as for previous surveys, consisting of 33 templates with five receiver lines and twelve source profiles perpendicular to the receiver lines. Seismic processing of the recently acquired data has resulted in preliminary observations which can be summarized as follows: As in previous seismic repeat surveys, a clear CO2 signature is observed at the top of the storage formation. No systematic amplitude changes are observed above the reservoir which might indicate leakage. Compared to the second repeat survey acquired in 2012, the lateral extent of the CO2 plume seems to have been reduced, which may be an indication for ongoing (and relatively fast) dissolution of the CO2 in the formation brine and diffusion into very thin layers indicating pressure release.
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