History-matching flow simulations and time-lapse seismic data from the Sleipner CO ₂ plume

Abstract

Since its inception in 1996, the CO 2 injection operation at Sleipner has been monitored by 3D time-lapse seismic surveys. Striking images of the CO 2 plume have been obtained showing a multi-tier feature of high reflectivity. In the medium to longer term, the topmost layer of CO 2 , accumulating and migrating directly beneath the topseal, is the main determinant of storage site performance. Fortunately it is this topmost layer that can be most accurately characterized, its rate of growth quantified, and CO 2 flux arriving at the reservoir top estimated. The latter is mostly controlled by pathway flow through thin intra-reservoir mudstones. This has increased steadily with time, suggesting either that pathway transmissivities are increasing with time and/or the pathways are becoming more numerous. Detailed 3D history-matching of the topmost layer cannot easily match the observed rate of spreading. Isotropic permeabilities result in a stronger radial component than observed and a degree of anisotropic permeability, higher in a north-south direction, is possible. The main contributor to the mismatch, however, is likely to be small but significant uncertainty in the depth conversion. Irrespective of uncertainty, the observed rate of lateral migration seems to require very high permeabilities, and is, moreover, suggestive of a topseal which behaves like a 'hard' impermeable flow barrier. Detailed studies such as this will provide important constraints on longer term predictive models of plume evolution and storage performance which are key regulatory requirements.

Offshore CO 2 storage: Sleipner natural gas field beneath the North Sea

“…A number of approaches have been tried, mainly within the CO2ReMoVe project (www.co2remove.com). These include model-based pre-and post-stack inversion (Clochard et al 2010), constrained AVO, common-focus-point imaging, spectral decomposition and velocity-attenuation tomography, and are summarised in Chadwick et al (2010) and references therein. It is perhaps fair to say that the efficacy of many of these purely seismic techniques is limited by the strong thin-layer tuning effects which tend to swamp the more subtle reflectivity changes on both pre-and post-stack data.…”

Potential structures for CO₂ geological storage in the Baltic Sea: Case study offshore Latvia

“…In addition, a number of papers have been published during last years, including numerical modelling of CO 2 plume dissolution mechanisms in an aquifer (Audigane et al, 2011), CO 2 fluid flow studies and 2D/3D modelling, associated with the fault system in long and short terms (Audigane et al, 2007;Chang et al, 2008;Grimstad et al, 2009;Chadwick & Noy, 2010). The last seismic numerical modelling results represent performance of seismic techniques and methods in detection of presence, evolution, migration and leakage of CO 2 in the storage reservoir (Rossi et al, 2008;Picotti et al, 2012).…”

Numerical Simulation of CO2 Sequestration in Large Saline Aquifers

“…Due to the low permeability Figure 25. eismic image of Utsira formation after 9 years of injection, S-N cross-section [24] Numerical Simulation of CO 2 Sequestration in Large Saline Aquifers http://dx.doi.org/10.5772/57065…”