Monitoring CO2 storage using ghost reflections retrieved from seismic interferometry

Time-lapse seismic monitoring constitutes the foundation for most monitoring programmes involving CO2 storage. Two major sources of uncertainty in the estimation of changes in the reservoir properties like saturation and pressure, using time-lapse seismics, are the non-repeatability of the source positions and the difficulty to separate the effect of the overburden from that of the changes taking place in a CO2 reservoir. In order to address those challenges, we propose a new concept of using non-physical (ghost) reflection events retrieved by seismic interferometry. We test this concept on data of realistic numerical modelling and scaled laboratory experiments, both representing a horizontally layered subsurface. Our results demonstrate that the seismic reflection ghosts can indeed be used advantageously to monitor changes in the CO2 reservoir.

► We propose an application of seismic interferometry for CO2 reservoir monitoring.
► For this we use non-physical arrivals from seismic interferometry.
► We monitor layer-specific changes in the seismic velocities.
► We demonstrate the method using numerically modelled data.
► We demonstrate the method using ultrasonic laboratory data.