Department of Earth Science

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Masterprosjekt - energi / ressurser

Monitoring of underground CO2 storage and possible leakage - Camilla Wikum

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Underground CO2 storage has been proposed to mitigate climate change caused by increased levels of CO2 in the atmosphere. This CO2 storage is currently being tested at a few sites such as Sleipner. However, in order for it to be successful, the number of storage
sites has to increase significantly. All these sites, typically depleted hydrocarbon reservoirs, need to be monitored regularly so that the concentration of CO2 throughout the reservoir can be determined and possible leakage through the caprock can be detected. One of the main ways to do this is by using time-lapse seismics.

Monitoring of CO2 storage in a large number of very different subsurface reservoirs requires accurate and flexible seismic monitoring techniques. Though seismic monitoring is relatively successful at for example Sleipner, relatively large uncertainties still exist. Two of the main sources of uncertainties are the seismic resolution (horizontal and, especially, vertical, resolution) and the relation between rock physics and seismics. In this project both these issues will be addressed by studying and improving seismic modeling and imaging/inversion algorithms.

All seismic imaging and inversion methods require a forward modeling method. In order to better understand the resolution of seismic images and inverted models it is therefore important to have a reliable forward modeling method. Moreover, various theoretical
resolution predictions can be tested if this forward modeling method is flexible and fast, even in realistic (i.e. complex 3D heterogeneous visco-elastic) models. A good class of modeling methods that satisfies these conditions are ray- and scattering-based modeling methods. These will therefore be the main modeling method used in this project. Various theoretical and numerical estimates of (horizontal and vertical) resolution using, for example, Fresnel zones and resolution matrices exist, but are mainly valid in lossless acoustic media. These estimates will be tested using multigrid high resolution modeling and imaging and extended to elastic and visco-elastic media. The improved resolution estimate will be compared and combined with uncertainties in various rock physics relationships. These will then be applied to estimate uncertainty in various CO2 plume shape and leakage scenarios and thus provide more accurate methods for monitoring the underground storage and leakage of CO2.

Krav for opptak: Bachelor Geophysics from UiB

Foreslåtte emner i spesialiseringen (60 sp):
GEOV274 (10 sp)
GEOV277 (10 sp)
SDG207 (10 sp)
GEOV375 (10sp)
Kiel course (5 sp)
GEOV352 (5 sp)
GEOV300 (5 sp)
Spesial pensum seismic modeling and imaging (5sp)