Repurposing an Abandoned North Sea Reservoir for CO2 Injection - a Sim2Seis Case Study

This paper evaluates the magnitude of 4D signal and ability to capture key features of interest to determine if 4D seismic monitoring of CO2 injection is possible at all. The current work follows on the earlier feasibility study conducted using Log2Seis. In this study, we simulated hydrocarbon gas production for six years and CO2 injection for six years in the Goldeneye field. We then carry out seismic modelling to create synthetic seismic response from the simulation results. The results indicated that CO2 injection should produce a visible signal and the fluid contact movement is detectable. The amplitude responses are not as visible as time shift signals, especially for thick intervals, suggesting that the latter may be a more preferential attribute to monitor CO2 injection into a gas reservoir. Although the current Sim2Seis study suggests that the signal is strong and easily seen, the inherent noise quality and variability in resolution will start to obfuscate these signals. Therefore, one should consider the noise model and illumination characteristics for the different seismic acquisitions when assessing the monitoring programme going forward.