Vibrometric Oy


Vibrometric Oy

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Ivandic M.,Uppsala University | Yang C.,Uppsala University | Luth S.,German Research Center for Geosciences | Cosma C.,Vibrometric Oy | Juhlin C.,Uppsala University
74th European Association of Geoscientists and Engineers Conference and Exhibition 2012 Incorporating SPE EUROPEC 2012: Responsibly Securing Natural Resources | Year: 2012

In April 2004, a research pilot project in the German town of Ketzin started as the first onshore CO2 storage project in Europe. Injection started in June 2008 and until the latest repeat survey in February 2011 around 45 kilotons of CO2 had been injected into a saline aquifer at approximately 630 m depth. Different seismic methods, such as time-lapse Vertical Seismic Profiling, Crosswell, Moving Source Profiling and surface seismics have been employed to detect and monitor changes in the reservoir. We present here timelapse results from sparse pseudo-3D seismic surveying with a radial distribution of acquisition profiles directed towards the approximate location of the injection well, which were acquired to link downhole surveys with full 3D surface seismic surveys. The results are consistent with the 3D seismic time-lapse studies over the injection site and show that the sparse 3D geometry can be used to qualitatively map the CO2 in the reservoir at a significantly lower effort than the full 3D surveying. The last repeat survey indicates preferential migration of the CO2 to the west. There are no indications of migration into the caprock on either of the repeat surveys. The same observation was obtained from the full 3D dataset.

Gotz J.,German Research Center for Geosciences | Luth S.,German Research Center for Geosciences | Krawczyk C.M.,Leibniz Institute for Applied Geophysics | Krawczyk C.M.,TU Berlin | Cosma C.,Vibrometric Oy
International Journal of Geophysics | Year: 2016

At the CO2 storage pilot site near the town of Ketzin (35 km west of Berlin, Germany) the sandstone reservoir at 630 m-650 m depth is thin and heterogeneous. The time-lapse analysis of zero-offset VSP measurements shows that CO2-induced amplitude changes can be observed on near-well corridor stacks. Further, we investigate whether CO2-induced amplitude changes in the monitoring data can be used to derive geometrical and petrophysical parameters governing the migration of CO2 within a brine saturated sandstone aquifer. 2D seismic-elastic modelling is done to test the processing workflow and to perform a wedge modelling study for estimation of the vertical expansion of the CO2 plume. When using the NRMS error as a measure for the similarity between the modelled and recorded repeat traces, the best match is achieved for a plume thickness of 6-7 m within the reservoir sandstone of 8 m thickness. With band limited impedance inversion a velocity reduction at the top of the reservoir of 30%, influenced by casing reverberations as well as CO2 injection, is found. The relation of seismic amplitude to CO2 saturated layer thickness and CO2-induced changes in P-wave velocities are important parameters for the quantification of the injected CO2 volume. © 2014 Julia Götz et al.

Juhojuntti N.,Uppsala University | Juhojuntti N.,Geological Survey of Sweden | Wood G.,Cameco Corporation | Juhlin C.,Uppsala University | And 3 more authors.
Geophysics | Year: 2012

Three-dimensional seismic reflection measurements have been used to assist mine planning at the Millennium uranium deposit, Canada. The deposit is located within the crystalline basement, separated from the overlying Athabasca Basin sediments by an unconformity potentially associated with significant fluid flow. The primary objective of the ∼6.5 km 2 survey was to image the unconformity and possible post-Athabasca deformation structures in and around the deposit. Clear unconformity reflections are observed within most of the survey area, although there are amplitude variations due to complex geology, including intense hydrothermal clay alteration around the deposit. Finite-difference modeling indicates that the wide-angle character of the unconformity reflections is due to a gradual velocity increase at the unconformity. The reflections are obscured by large time delays, due to Quaternary sediments covering the area, making refraction static corrections crucial. The seismic interpretation shows large variations in the unconformity depth (from approximately 430 to 650 m), indicating a pronounced basement depression that coincides with a gravity low. Reflections from the unconformity are vague within the depression, especially in the vicinity of the deposit. Although the orebody is not directly visible in the seismic image, there is a lack of reflectivity coincident with the alteration surrounding the mineralization. We also observed reflections which likely originate at the contact between the altered and fresh basement rock located beneath the deposit. The seismic data further indicate post-Athabasca faults in the vicinity of the orebody. Based on the initial seismic interpretation, the depth of the crown pillar was adjusted and the mine infrastructure moved away from areas interpreted to be affected by the intense hydrothermal alteration surrounding the deposit. The capability to image the unconformity, post-Athabasca structure, and hydrothermal alteration also highlights the potential use of seismic surveys in uranium exploration. © 2012 Society of Exploration Geophysicists.

Kazemeini S.H.,Uppsala University | Kazemeini S.H.,University of Texas at Austin | Yang C.,Uppsala University | Juhlin C.,Uppsala University | And 2 more authors.
Geophysics | Year: 2010

Restricted resolution imposes limits on the detection of subsurface geologic features using surface seismic data. Despite great improvements in acquisition and processing techniques in recent years, seismic data still suffer from limited resolution. Detailed subsurface information on the geologic conditions at depth cannot always be attained from conventional surface seismic data. For the area of this study, the carbon dioxide (CO2) storage site at Ketzin, Germany, high seismic resolution is required for mapping the internal structure of the main target reservoir. Processing of the 3D surface seismic data using conventional methods did not provide optimum resolution. The spectral blueing technique attempts to enhance the surface seismic data resolution. Well-log data generally show a blue spectrum with higher-amplitudes at the higher frequencies than the commonly assumed white reflection series. By designing and applying one or several operators to poststack data, it has been possible to better match the reflectivity series and improve resolution. Applying the blueing operator to prestack data was investigated to possibly improve seismic resolution, produce more consistent results, and cause fewer ringing artifacts than when applied to poststack data. Prestack blueing, poststack blueing, and no blueing of the Ketzin 3D seismic data were compared with zero-offset vertical seismic profile (VSP) and synthetic seismograms. The comparison shows that prestack spectral blueing can indeed enhance seismic resolution with fewer artifacts associated with it than the poststack technique. The prestack and poststack spectral blueing approaches improve the well to seismic tie. © 2010 Society of Exploration Geophysicists.

Zhang F.,Uppsala University | Juhlin C.,Uppsala University | Cosma C.,Vibrometric Oy | Tryggvason A.,Uppsala University | Pratt R.G.,University of Western Ontario
Geophysical Journal International | Year: 2012

Geological storage of CO2 is one means of mitigating the effects of continued burning of fossil fuels for power generation. An important component in the storage concept is the monitoring of the CO2 distribution at depth. Seismic methods can play a significant role in this monitoring, in particular cross-well methods are of interest due to their high resolution. For these purposes, a series of cross-well seismic surveys were acquired within the framework of the CO2SINK project at Ketzin, Germany, at various stages of an injection test. We study here the potential of applying cross-well seismic waveform tomography to monitor the CO2 injection process. First, we test the method on synthetic data having a similar geometry to that of the real data. After successful application on the synthetic data, we test the method on the real data acquired at the Ketzin Site. Traveltime tomography images of the real data show no observable differences between the surveys. However, seismic waveform tomography difference images show significant differences. A number of these differences are artefacts that can probably be attributed to inconsistent receiver coupling between the different surveys. However, near the injection horizon, below the caprock, a velocity decrease is present that is consistent with that expected from the injection process. © 2012 The Authors Geophysical Journal International © 2012 RAS.

Cosma C.,Vibrometric Oy | Enescu N.,Vibrometric Oy | Heikkinen E.,Pöyry
Rock Characterisation, Modelling and Engineering Design Methods - Proceedings of the 3rd ISRM SINOROCK 2013 Symposium | Year: 2013

ONKALO is the underground rock characterisation built for the final disposal of spent nuclear fuel at Olkiluoto, Finland. Geology, geophysics, hydro-geology, geochemistry and rock mechanics contribute to bedrock studies conducted during repository construction to ensure the suitability of the bedrock for the final disposal. A high-resolution 3D reflection seismic imaging survey was conducted in 2009 at a depth of app. 350 m. Lines 240 m long were measured, with source stations spaced at 1 m and receivers at 3 m, respectively. Measurements were conducted withahydraulic impact source that was usedonthe tunnel wall and floor. Fractures were imaged couple of hundred meters away from the tunnel. The location of the target features was achieved by using 3-component receivers, two parallel source lines and 3D vector migration schemes. IP (Image Point) migration was found particularly useful for imaging narrow and roughly planar features of diverse orientations. © 2013 Taylor & Francis Group.

Cosma C.,Vibrometric Oy | Enescu N.,Vibrometric Oy | Heikkinen E.,Pöyry
Near Surface 2010 - 16th European Meeting of Environmental and Engineering Geophysics | Year: 2010

Seismic and Radar investigations performed in 2009 at Olkiluoto in a niche excavated on the side of the ONKALO access tunnel. The objectives have been to confirm the existence of the EDZ at Olkiluoto, to evaluate its extent and to determine its physical characteristics. Three crosshole and one singlehole seismic sections have been measured before and after the excavation. The results of these investigations are presented and discussed. As direct consequence of the EDZ along the tunnel wall, a decrease of acoustic P and S wave velocities and an increase in attenuation can be observed both from direct cross-hole measurements done in the immediate vicinity of the excavated wall and from remote sensing by side-scan measurements done in a borehole parallel to the tunnel wall and away from it. The existence of the EDZ has been proven beyond doubt by both transmission and reflection seismic imaging.

Yang C.,Uppsala University | Juhlin C.,Uppsala University | Enescu N.,Uppsala University | Cosma C.,Vibrometric Oy | Luth S.,Helmholtz Center Potsdam
Near Surface Geophysics | Year: 2010

Baseline moving source profiling data were acquired in borehole Ketzin 202/2007 along seven lines at the Ketzin CO2 injection site in 2007. The data were recorded on eight three-component receivers spaced 10 m apart over a depth interval of 470-540 m. The main objective of the moving source profile survey was to generate high-resolution seismic images around the borehole. This was especially important given that the 3D surface seismic data in the area have a low fold at the injection site. Mapping of the sandy layers in the target formation (Stuttgart Formation) at around 630 m, the approximate CO2 injection depth, was another objective of the research. A comparison with repeat moving source profile surveys, during and after the injection, will be done in the future. A processing sequence consisting in hodogram analysis, wavefield separation and prestack migration was applied to the moving source profile data. A median filter was used to separate the downgoing and upgoing wave modes. The data were processed to generate depth migrated images in the vicinity of the borehole that could be compared with the 3D surface seismic data. Both the modelling studies that were carried out and the migrated images, indicate that the sandy layers within the Stuttgart Formation can potentially be imaged in the moving source profile data whereas reflections from these layers are not as clearly observed in the 3D surface seismic data. © 2010 European Association of Geoscientists & Engineers.

Ivandic M.,Uppsala University | Yang C.,Uppsala University | Luth S.,Helmholtz Center Potsdam | Cosma C.,Vibrometric Oy | Juhlin C.,Uppsala University
Journal of Applied Geophysics | Year: 2012

The Ketzin pilot site is the first European on-shore CO2 storage project site. Injection started in June 2008 and until the latest repeat survey in February 2011 around 45,000t of CO2 had been injected into a saline aquifer at approximately 630m depth. Seismic monitoring methods that have been applied at the Ketzin site comprise baseline and repeat observations at various scales. We present here time-lapse results from sparse 3D seismic data measurements at Ketzin, which were acquired to link downhole surveys with conventional 3D surface seismic surveys. The results are consistent with the 3D seismic time-lapse studies over the injection site and show that the sparse 3D geometry can be used to map the CO2 in the reservoir at a significantly lower effort than the conventional 3D surveying. The last repeat survey indicates preferential migration of the CO2 to the west. There are no indications of migration into the caprock on either of the repeat surveys. © 2012 Elsevier B.V.

Bergmann P.,Helmholtz Center Potsdam | Yang C.,Uppsala University | Luth S.,Helmholtz Center Potsdam | Juhlin C.,Uppsala University | Cosma C.,Vibrometric Oy
Journal of Applied Geophysics | Year: 2011

The Ketzin project provides an experimental pilot test site for the geological storage of CO2. Seismic monitoring of the Ketzin site comprises 2D and 3D time-lapse experiments with baseline experiments in 2005. The first repeat 2D survey was acquired in 2009 after 22kt of CO2 had been injected into the Stuttgart Formation at approximately 630m depth. Main objectives of the 2D seismic surveys were the imaging of geological structures, detection of injected CO2, and comparison with the 3D surveys. Time-lapse processing highlighted the importance of detailed static corrections to account for travel time delays, which are attributed to different near-surface velocities during the survey periods. Compensation for these delays has been performed using both pre-stack static corrections and post-stack static corrections. The pre-stack method decomposes the travel time delays of baseline and repeat datasets in a surface consistent manner, while the latter cross-aligns baseline and repeat stacked sections along a reference horizon. Application of the static corrections improves the S/N ratio of the time-lapse sections significantly. Based on our results, it is recommended to apply a combination of both corrections when time-lapse processing faces considerable near-surface velocity changes. Processing of the datasets demonstrates that the decomposed solution of the pre-stack static corrections can be used for interpretation of changes in near-surface velocities. In particular, the long-wavelength part of the solution indicates an increase in soil moisture or a shallower groundwater table in the repeat survey. Comparison with the processing results of 2D and 3D surveys shows that both image the subsurface, but with local variations which are mainly associated to differences in the acquisition geometry and source types used. Interpretation of baseline and repeat stacks shows that no CO2 related time-lapse signature is observable where the 2D lines allow monitoring of the reservoir. This finding is consistent with the time-lapse results of the 3D surveys, which show an increase in reflection amplitude centered around the injection well. To further investigate any potential CO2 signature, an amplitude versus offset (AVO) analysis was performed. The time-lapse analysis of the AVO does not indicate the presence of CO2, as expected, but shows signs of a pressure response in the repeat data. © 2011 Elsevier B.V.

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