Summary
We present the results of time-lapse seismic data processing of two vintages of data acquired prior to CO2 injection at the Aquistore CO2 storage site. The aim of this study is to determine the utility of a sparse permanent seismic array as a time-lapse measurement tool so as to improve the cost effectiveness of CO2 monitoring at Aquistore. Using a processing flow to optimise both the seismic image and similarity between the vintages, we processed the baseline and monitor volumes using the simultaneous processing method. Additionally, we evaluated the nRMS at 13 different stages of processing in a pre-and post-equalisation analysis to evaluate the impact of processing sequence on reducing the non-repeatable difference between the vintages. The global nRMS was reduced from 1.13 for the raw datasets to 0.13 after migration with further reduction to 0.07 after the post-stack cross-equalisation processing sequence. A simulation of the changes in rock properties and seismic response due to various scenarios of CO2 injection in the reservoir suggests that CO2 reservoir monitoring at Aquistore is not limited by the repeatability of the surveys.