Quantitative interpretation of CO2 plume from Sleipner (North Sea), using post-stack inversion and rock physics modeling

Ghosh, Ranjana; Sen, Mrinal K.; Vedanti, Nimisha

doi:10.1016/j.ijggc.2014.11.002

Cited by 47 publications

(19 citation statements)

References 46 publications

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“…Golding and Huppert (2011) agree with Queißer and Singh (2013) that saturation is probably greater than 30%. Ghosh et al (2015) quantify the CO 2 saturation with a maximum of 20% for the uniform saturation case and with a maximum of 80% for the patchy mixing case, with an uncertainty of approximately 5%-7%. To mitigate the uncertainty related to a rock physics model, they compare the injected CO 2 mass with the estimated mass corresponding to the two kinds of distributions and they conclude that patchy distribution is more likely.…”

Section: Discussionmentioning

confidence: 99%

“…Buddensiek et al (2010) apply the advanced AVO methodology developed by Causse et al (2007), to analyze the top-most reflection from a series of thin-layer reflections at Sleipner. Ghosh et al (2015) estimate CO 2 saturation from poststack seismic impedance considering dual porosity and a pressure-dependent differential effective medium model.…”

Section: Introductionmentioning

confidence: 99%

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Quantitative seismic characterization of CO₂ at the Sleipner storage site, North Sea

et al. 2017

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Reliable quantification of carbon dioxide (CO 2 ) properties and saturation is crucial in the monitoring of CO 2 underground storage projects. We have focused on quantitative seismic characterization of CO 2 at the Sleipner storage pilot site. We evaluate a methodology combining high-resolution seismic waveform tomography, with uncertainty quantification and rock physics inversion. We use full-waveform inversion (FWI) to provide highresolution estimates of P-wave velocity V P and perform an evaluation of the reliability of the derived model based on posterior covariance matrix analysis. To get realistic estimates of CO 2 saturation, we implement advanced rock physics models taking into account effective fluid phase theory and patchy saturation. We determine through sensitivity tests that the estimation of CO 2 saturation is possible even when using only the P-wave velocity as input. After a characterization of rock frame properties based on log data prior to the CO 2 injection at Sleipner, we apply our two-step methodology. The FWI result provides clear indications of the injected CO 2 plume being observed as low-velocity zones corresponding to thin CO 2 filled layers. Several tests, varying the rock physics model and CO 2 properties, are then performed to estimate CO 2 saturation. The results suggest saturations reaching 30%-35% in the thin sand layers and up to 75% when patchy mixing is considered. We have carried out a joint estimation of saturation with distribution type and, even if the inversion is not wellconstrained due to limited input data, we conclude that the CO 2 has an intermediate pattern between uniform and patchy mixing, which leads to saturation levels of approximately 25% AE 15%. It is worth noting that the 2D section used in this work is located 533 m east of the injection point. We also conclude that the joint estimation of CO 2 properties with saturation is not crucial and consequently that knowing the pressure and temperature state of the reservoir does not prevent reliable estimation of CO 2 saturation.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Quantitative seismic characterization of CO₂ at the Sleipner storage site, North Sea

et al. 2017

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“…Ghosh et al . () also found that the CO 2 phase is not fully patchy or uniformly saturated in the reservoir. Zhang, Lu and Zhu () and Chadwick et al .…”

Section: Discussionmentioning

confidence: 84%

“…Recent work by Ghosh et al . () gives estimations between 0.20 and 0.80 depending on the mixture type (patchiness exponent). In previous tests using the same methodology shown by Dupuy et al .…”

Section: Discussionmentioning

confidence: 99%

CO₂ saturation estimates at Sleipner (North Sea) from seismic tomography and rock physics inversion

Yan

Dupuy

Romdhane

et al. 2018

Geophysical Prospecting

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CO2 saturations are estimated at Sleipner using a two‐step imaging workflow. The workflow combines seismic tomography (full‐waveform inversion) and rock physics inversion and is applied to a two‐dimensional seismic line located near the injection point at Sleipner. We use baseline data (1994 vintage, before CO2 injection) and monitor data that was acquired after 12 years of CO2 injection (2008 vintage). P‐wave velocity models are generated using the Full waveform inversion technology and then, we invert selected rock physics parameters using an rock physics inversion methodology. Full waveform inversion provides high‐resolution P‐wave velocity models both for baseline and monitor data. The physical relations between rock physics properties and acoustic wave velocities in the Utsira unconsolidated sandstone (reservoir formation) are defined using a dynamic rock physics model based on well‐known Biot–Gassmann theories. For data prior to injection, rock frame properties (porosity, bulk and shear dry moduli) are estimated using rock physics inversion that allows deriving physically consistent properties with related uncertainty. We show that the uncertainty related to limited input data (only P‐wave velocity) is not an issue because the mean values of parameters are correct. These rock frame properties are then used as a priori constraint in the monitor case. For monitor data, the Full waveform inversion results show nicely resolved thin layers of CO2–brine saturated sandstones under intra‐reservoir shale layers. The CO2 saturation estimation is carried out by plugging an effective fluid phase in the rock physics model. Calculating the effective fluid bulk modulus of the brine–CO2 mixture (using Brie equation in our study) is shown to be the key factor to link P‐wave velocity to CO2 saturation. The inversion tests are done with several values of Brie/patchiness exponent and show that the CO2 saturation estimates are varying between 0.30 and 0.90 depending on the rock physics model and the location in the reservoir. The uncertainty in CO2 saturation estimation is usually lower than 0.20. When the patchiness exponent is considered as unknown, the inversion is less constrained and we end up with values of exponent varying between 5 and 20 and up to 33 in specific reservoir areas. These estimations tend to show that the CO2–brine mixing is between uniform and patchy mixing and variable throughout the reservoir.

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“…A number of advanced techniques have been tested here and some are summarised in . These include, inter alia, pre-and post-stack inversion Ghosh et al, 2015); full waveform inversion (Queisser and Singh, 2013); spectral inversion (Rubino et al, 2011b); spectral attenuation (Rubino et al, 2011a); spectral decomposition ; amplitude-versus-angle analysis (Rabben and Ursin, 2011) and travel-time / attenuation tomography (Rossi et al, 2012). The varied approaches have all helped to understand better the complexity of the CO 2 plume at a range of scales and have added to a progressive reduction in uncertainty of some key parameters.…”

Section: D Seismicsmentioning

confidence: 99%

The state of the art in monitoring and verification—Ten years on

Jenkins

Chadwick

Hovorka

2015

International Journal of Greenhouse Gas Control

187

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a b s t r a c tIn the ten years since publication of the IPCC Special Report on CCS, there has been considerable progress in monitoring and verification (M&V). Numerous injection projects, ranging from small injection pilots to much larger longer-term commercial operations, have been successfully monitored to the satisfaction of regulatory agencies, and technologies have been adapted and implemented to demonstrate containment, conformance, and no environmental impact. In this review we consider M&V chiefly from the perspective of its ability to satisfy stakeholders that these three key requirements are being met. From selected project examples, we show how this was done, and reflect particularly on the nature of the verification process. It is clear that deep-focussed monitoring will deliver the primary requirement to demonstrate conformance and containment and to provide early warning of any deviations from predicted storage behaviour. Progress in seismic imaging, especially offshore, and the remarkable results with InSAR from In Salah are highlights of the past decade. A wide range of shallow monitoring techniques has been tested at many sites, focussing especially on the monitoring of soil gas and groundwater. Quantification of any detected emissions would be required in some jurisdictions to satisfy carbon mitigation targets in the event of leakage to surface: however, given the likely high security of foreseeable storage sites, we suggest that shallow monitoring should focus mainly on assuring against environmental impacts. This reflects the low risk profile of well selected and well operated storage sites and recognizes the over-arching need for monitoring to be directed to specific, measureable risks. In particular, regulatory compliance might usefully involve clearer articulation of leakage scenarios, with this specificity making it possible to demonstrate "no leakage" in a more objective way than is currently the case. We also consider the monitoring issues for CO 2 -EOR, and argue that there are few technical problems in providing assurance that EOR sites are successfully sequestering CO 2 ; the issues lie largely in linking existing oil and gas regulations to new greenhouse gas policy. We foresee that, overall, monitoring technologies will continue to benefit from synergies with oil and gas operations, but that the distinctive regulatory and certification environments for CCS may pose new questions. Overall, while there is clearly scope for technical improvements, more clearly posed requirements, and better communication of monitoring results, we reiterate that this has been a decade of significant achievement that leaves monitoring and verification well placed to serve the wider CCS enterprise.Crown

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Quantitative interpretation of CO2 plume from Sleipner (North Sea), using post-stack inversion and rock physics modeling

Cited by 47 publications

References 46 publications

Quantitative seismic characterization of CO₂ at the Sleipner storage site, North Sea

Quantitative seismic characterization of CO₂ at the Sleipner storage site, North Sea

CO₂ saturation estimates at Sleipner (North Sea) from seismic tomography and rock physics inversion

The state of the art in monitoring and verification—Ten years on

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Quantitative interpretation of CO2 plume from Sleipner (North Sea), using post-stack inversion and rock physics modeling

Cited by 47 publications

References 46 publications

Quantitative seismic characterization of CO2 at the Sleipner storage site, North Sea

Quantitative seismic characterization of CO2 at the Sleipner storage site, North Sea

CO2 saturation estimates at Sleipner (North Sea) from seismic tomography and rock physics inversion

The state of the art in monitoring and verification—Ten years on

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Quantitative seismic characterization of CO₂ at the Sleipner storage site, North Sea

Quantitative seismic characterization of CO₂ at the Sleipner storage site, North Sea

CO₂ saturation estimates at Sleipner (North Sea) from seismic tomography and rock physics inversion