Seismic monitoring of CO<sub>2</sub>injected into a marine acquifer

Eiken, Ola; Brevik, Ivar; Nitg-Tno, R. Arts; Sintef, E. Lindeberg; Fagervik, K.; Geco-Prakla, Schlumberger

doi:10.1190/1.1815725

Cited by 39 publications

(31 citation statements)

References 1 publication

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“…They are visible on all station combinations and on all components. The injection of CO 2 into a porous layer changes the medium and lowers the seismic velocities with respect to a reference state before the injection (Eiken et al 2000;Kazemeini et al 2010;Ivanova et al 2012). Therefore, we expect a monotonic decrease of the seismic velocities over the period of the injection because the injection is almost continuous with a constant rate (on average).…”

Section: Discussionmentioning

confidence: 99%

Monitoring of environmental influences on seismic velocity at the geological storage site for CO2 in Ketzin (Germany) with ambient seismic noise

Gassenmeier¹,

Sens‐Schönfelder²,

Delatre³

et al. 2014

Geophysical Journal International

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Originally published as:Gassenmeier, M., Sens-Schönfelder, C., Delatre, M., Korn, M. (2015): Monitoring of environmental influences on seismic velocity at the geological storage site for CO2 in Ketzin (Germany) with ambient seismic noise. S U M M A R YRegarding the exploitation of natural resources, storage of waste or subsurface construction, there is an increasing need to obtain comprehensive knowledge about the subsurface and its temporal changes. We investigate the possibility of a passive monitoring using ambient seismic noise, which is cheap and continuous compared to active seismics. We work with data acquired with a seismic network in Ketzin (Germany) where 67 271 tons of CO 2 were injected from 2008 June until 2013 August into a saline aquifer at a depth of about 650 m. Monitoring the expansion of the CO 2 plume is essential for the characterization of the reservoir as well as the detection of potential leakage. By cross-correlating about 4 yr of passive seismic data in a frequency range of 0.05-4.5 Hz we found periodic velocity variations with a period of approximately 1 yr that cannot be caused by the CO 2 injection. The prominent direction of the noise wavefield indicates a wind farm as the dominant source providing the temporally stable noise field. This spacial stability excludes variations of the noise source distribution as a cause of spurious velocity variations. Based on an amplitude decrease associated with time windows towards later parts of the coda, we show that the variations must be generated in the shallow subsurface. A comparison to groundwater level data reveals a direct correlation between depth of the groundwater level and the seismic velocity. The influence of ground frost on the seismic velocities is documented by a sharp increase of velocity when the maximum daily temperature stays below 0 • C. Although the observed periodic changes and the changes due to ground frost affect only the shallow subsurface, they mask potential signals of material changes from the reservoir depths.

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Section: Discussionmentioning

confidence: 99%

Monitoring of environmental influences on seismic velocity at the geological storage site for CO2 in Ketzin (Germany) with ambient seismic noise

Gassenmeier¹,

Sens‐Schönfelder²,

Delatre³

et al. 2014

Geophysical Journal International

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“…Modeling showed that the presence of gas induces a dramatic decrease of the P-wave velocity even for moderate CO 2 saturation, and consequently impacts the Top Utsira Formation reflection coefficient. 25% CO 2 saturation doubles the reflected amplitudes, while 100% gas saturation triples the reflected amplitudes (Eiken et al, 2000). Another seismic indication of the subsurface properties due to gas injection is the measured velocity pushdown determined by crosscorrelating the seismic traces between the baseline and the different monitoring surveys.…”

Section: Nrms (%)mentioning

confidence: 99%

Surface-consistent matching filters for time-lapse processing

Almutlaq

Margrave

2012

SEG Technical Program Expanded Abstracts 2012

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The problem of mismatch between repeated time-lapse seismic surveys remains a challenge, particularly for land acquisition. In this dissertation, we present a new algorithm, which is an extension of the surface-consistent model, and which minimizes the mismatch between surveys, hence improving repeatability.We introduce the concept of surface-consistent matching filters (SCMF) for processing time-lapse seismic data, where matching filters are convolutional filters that minimize the sum-squared error between two signals. Since in the Fourier domain, a matching filter is the spectral ratio of the two signals, we extend the well known surface-consistent hypothesis such that the data term is a trace-by-trace spectral ratio of two datasets instead of only one (i.e. surface-consistent deconvolution). To avoid unstable division of spectra, we compute the spectral ratios in the time domain by first designing tracesequential, least-squares matching filters, then Fourier transforming them. A subsequent least-squares solution then factors the trace-sequential matching filters into four operators: two surface-consistent (source and receiver), and two subsurface-consistent (offset and midpoint).We apply the algorithm to two datasets: a synthetic time-lapse model and field data from a CO 2 monitoring site in Northern Alberta. In addition, two common time-lapse processing schemes (independent processing and simultaneous processing) are compared.We present a modification of the simultaneous processing scheme as a direct result of applying the new SCMF algorithm. The results of applying the SCMF together with the new modified simultaneous processing flow reveal the potential benefit of the method, however some challenges remain, specifically in the presence of random noise.i

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“…The seismic images obtained highlight the strong effect of CO 2 injection on the seismic response, both on seismic amplitudes and traveltimes inside the CO 2 plume (Eiken et al, 2000).…”

Section: Case Study: the Co Storage Reservoir At Sleipner Sitementioning

confidence: 99%

4D Joint Stratigraphic Inversion of Prestack Seismic Data: Application to the CO₂Storage Reservoir (Utsira Sand Formation) at Sleipner Site

Labat

Delépine

Clochard

et al. 2012

Oil Gas Sci. Technol. – Rev. IFP Energies nouvelles

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Résumé -Inversion stratigraphique jointe 4D de données sismiques avant sommation : application au réservoir de stockage de CO 2 (Formation Utsira) du site de Sleipner -Le monitoring sismique est couramment utilisé dans l'industrie pétrolière pour suivre l'évolution des propriétés des réservoirs au cours de leur production. Nous présentons ici une méthodologie d'inversion stratigraphique 4D qui fournit une estimation des variations d'impédances des ondes P et S dans le réservoir, par inversion de données de sismiques répétées avant-sommation. L'inversion 4D est implémentée dans le domaine temps et nécessite une loi de mise à l'échelle des temps de trajets pour chaque jeu de données de sismique répétée (aussi appelé "millésime") afin de mettre en correspondance les temps d'arrivée d'événements homologues observés sur les jeux de données appelés référence et monitors. Cette opération est souvent appelée "warping". L'inversion 4D est une méthodologie qui comporte trois étapes : la première étape consiste à inverser chaque millésime sismique séparément, pour produire autant de distributions en impédances P et S que de jeux de données considérés. La seconde étape utilise l'information des impédances P disponibles pour résoudre le problème du warping, qui est un point clé pour la troisième et dernière étape : l'inversion jointe de tous les millésimes sismiques disponibles. Cette séquence d'inversion 4D a été appliquée aux jeux de données enregistrés sur le réservoir de stockage de CO 2 du site norvégien de Sleipner (Mer du Nord). Ce dernier est devenu un site industriel de référence pour le stockage à long terme du dioxyde de carbone (CO 2 ) dans un aquifère salin, la formation des sables de l'Utsira. Nous avons focalisé notre étude sur l'inversion 4D des millésimes 1994 et 2006, acquise respectivement avant et dix ans après le début de l'injection de CO 2 . Le warping a fourni une loi de mise à l'échelle des temps de propagation avec un retard maximum d'environ 45 ms à la base de l'aquifère Utsira. L'inversion 4D jointe a donné des résultats plus cohérents que les inversions 3D : l'inversion 4D fournit en particulier des impédances P pour les grès saturés en CO 2 qui sont très proches des valeurs fournies par la physique des roches. Abstract

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Seismic monitoring of CO₂injected into a marine acquifer

Cited by 39 publications

References 1 publication

Monitoring of environmental influences on seismic velocity at the geological storage site for CO2 in Ketzin (Germany) with ambient seismic noise

Monitoring of environmental influences on seismic velocity at the geological storage site for CO2 in Ketzin (Germany) with ambient seismic noise

Surface-consistent matching filters for time-lapse processing

4D Joint Stratigraphic Inversion of Prestack Seismic Data: Application to the CO₂Storage Reservoir (Utsira Sand Formation) at Sleipner Site

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Seismic monitoring of CO2injected into a marine acquifer

Cited by 39 publications

References 1 publication

Monitoring of environmental influences on seismic velocity at the geological storage site for CO2 in Ketzin (Germany) with ambient seismic noise

Monitoring of environmental influences on seismic velocity at the geological storage site for CO2 in Ketzin (Germany) with ambient seismic noise

Surface-consistent matching filters for time-lapse processing

4D Joint Stratigraphic Inversion of Prestack Seismic Data: Application to the CO2Storage Reservoir (Utsira Sand Formation) at Sleipner Site

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Seismic monitoring of CO₂injected into a marine acquifer

4D Joint Stratigraphic Inversion of Prestack Seismic Data: Application to the CO₂Storage Reservoir (Utsira Sand Formation) at Sleipner Site