A feasibility and efficiency study of seismic waveform inversion for time-lapse monitoring of onshore CO2 geological storage sites using reflection seismic geometry
(English)Manuscript (preprint) (Other academic)
The monitoring of the CO2 distribution at depth is very important for onshore geological storage of CO2. Seismic methods are effective monitoring tools during and after the injection process, but are generally expensive and time consuming to perform. In this paper we perform a series of synthetic experiments in order to compare the seismic waveform inversion method with conventional seismic monitoring methods for time-lapse monitoring at CO2 geological storage sites. We mainly focus our study on seismic data sets with typical reflection acquisition geometries, that is far offset data is limited. Three synthetic seismic data sets (consisting of one baseline and two repeats) were generated by a third party 2D forward modeling code to compare the waveform inversion method with the conventional method. The area into which CO2 is injected is on the order of a few hundred meters wide and a few 10s of meters high and can be considered as a leak. We compare the waveform inversion results and conventional time-lapse results to determine how sparse spatial sub-sampling affects the results by successively increasing both the shot and receiver spacing. Aside from testing the influence of the shot and receiver spacing on the results, we also use a coarse starting model and increase the starting frequency to make the test more realistic. Our results show that, under certain conditions concerning noise, it may be possible to use a combination of sparse spatial sampling geometries and seismic waveform inversion to monitor CO2 injection sites. Regardless, seismic waveform inversion may be a good complement to standard CDP processing when monitoring CO2 injection.
CO2 monitoring, CO2 sequestration, time lapse, seismic waveform inversion
Earth and Related Environmental Sciences Geophysics
IdentifiersURN: urn:nbn:se:uu:diva-187138OAI: oai:DiVA.org:uu-187138DiVA: diva2:573803