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Application of the continuous wavelet transform on seismic data for mapping of channel deposits and gas detection at the CO2SINK site, Ketzin, Germany
Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
Geological Survey of Denmark and Greenland.
GeoForschungsZentrum Potsdam, Potsdam, Germany..
2009 (English)In: Geophysical Prospecting, ISSN 0016-8025, E-ISSN 1365-2478, Vol. 57, no 1, 111-123 p.Article in journal (Refereed) Published
Abstract [en]

Conventional seismic data are band limited and therefore, provide limited geological information. Every method that can push the limits is desirable for seismic data analysis.

Recently, time-frequency decomposition methods are being used to quickly extract geological information from seismic data and, especially, for revealing frequency dependent amplitude anomalies. Higher frequency resolution at lower frequencies and higher temporal resolution at higher frequencies are the objectives for different timefrequency decomposition methods. Continuous wavelet transform techniques, which are the same as narrow-band spectral analysis methods, provide frequency spectra with high temporal resolution without the windowing process associated with other techniques. Therefore, this technique can be used for analysing geological information associated with low and high frequencies that normally cannot be observed in conventional seismic data. In particular, the continuous wavelet transform is being used to detect thin sand bodies and also as a direct hydrocarbon indicator. This paper presents an application of the continuous wavelet transform method for the mapping of potential channel deposits, as well as remnant natural gas detection by mapping low-frequency anomalies associated with the gas. The study was carried out at the experimental CO2 storage site at Ketzin, Germany (CO2SINK). Given that reservoir heterogeneity and faulting will have significant impact on the movement and storage of the injected CO2, our results are encouraging for monitoring the migration of CO2 at the site. Our study confirms the efficiency of the continuous wavelet transform decomposition method for the detection of frequency-dependent anomalies that may be due to gas migration during and after the injection phase and in this way, it can be used for real-time monitoring of the injected CO2 from both surface and borehole

seismics.

 

Place, publisher, year, edition, pages
HOUTEN-Netherlands: Wiley-Blackwell on behalf of the European Association of Geoscientists & Engineers , 2009. Vol. 57, no 1, 111-123 p.
Keyword [en]
continuous wavelet transform, channel mapping, gas low frequency shadow, CO2SINK Project
National Category
Geophysics
Research subject
Geophysics Specialized In Solid Earth
Identifiers
URN: urn:nbn:se:uu:diva-104154DOI: 10.1111/j.1365-2478.2008.00723.xISI: 000261447600009OAI: oai:DiVA.org:uu-104154DiVA: diva2:219430
Projects
CO2SINK Project
Available from: 2009-05-27 Created: 2009-05-27 Last updated: 2017-12-13Bibliographically approved
In thesis
1. Seismic Investigations at the Ketzin CO2 Injection Site, Germany: Applications to Subsurface Feature Mapping and CO2 Seismic Response Modeling
Open this publication in new window or tab >>Seismic Investigations at the Ketzin CO2 Injection Site, Germany: Applications to Subsurface Feature Mapping and CO2 Seismic Response Modeling
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

3D seismic data are widely used for many different purposes. Despite different objectives, a common goal in almost all 3D seismic programs is to attain better understanding of the subsurface features. In gas injection projects, which are mainly for Enhanced Oil Recovery (EOR) and recently for environmental purposes, seismic data have an important role in the gas monitoring phase. This thesis deals with a 3D seismic investigation at the CO2 injection site at Ketzin, Germany. I focus on two critical aspects of the project: the internal architecture of the heterogeneous Stuttgart reservoir and the detectability of the CO2 response from surface seismic data.

Conventional seismic methods are not able to conclusively map the internal reservoir architecture due to their limited seismic resolution. In order to overcome this limitation, I use the Continuous Wavelet Transform (CWT) decomposition technique, which provides frequency spectra with high temporal resolution without the disadvantages of the windowing process associated with the other techniques. Results from applying this technique reveal more of the details of sand bodies within the Stuttgart Formation. The CWT technique also helps to detect and map remnant gas on the top of the structure. In addition to this method, I also show that the pre-stack spectral blueing method, which is presented for the first time in this research, has an ability to enhance seismic resolution with fewer artifacts in comparison with the post-stack spectral blueing method.

The second objective of this research is to evaluate the CO2 response on surface seismic data as a feasibility study for CO2 monitoring. I build a rock physics model to estimate changes in elastic properties and seismic velocities caused by injected CO2. Based on this model, I study the seismic responses for different CO2 injection geometries and saturations using one dimensional (1D) elastic modeling and two dimensional (2D) acoustic finite-difference modeling. Results show that, in spite of random and coherent noises and reservoir heterogeneity, the CO2 seismic response should be strong enough to be detectable on surface seismic data. I use a similarity-based image registration method to isolate amplitude changes due to the reservoir from amplitude changes caused by time shifts below the reservoir. In support of seismic monitoring using surface seismic data, I also show that acoustic impedance versus Poisson’s ratio cross-plot is a suitable attribute for distinguishing gas-bearing sands from brine-bearing sands.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2009. 73 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 657
Keyword
Seismic resolution, Spectral blueing, CO2 seismic response, Continuous Wavelet Transform Decomposition, 3D seismic baseline, CO2SINK project
National Category
Geophysics
Research subject
Geophysics Specialized In Solid Earth
Identifiers
urn:nbn:se:uu:diva-105032 (URN)978-91-554-7557-4 (ISBN)
Public defence
2009-09-01, Axel Hambergsalen Geocentrum, Villavägen 16, Uppsala, 10:00 (English)
Opponent
Supervisors
Projects
CO2SINK Project
Available from: 2009-06-04 Created: 2009-05-31 Last updated: 2009-06-15

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Kazemeini, Sayed HesammoddinJuhlin, Christopher

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