Full-Waveform Adaptive Monitoring for CCS

Summary Each carbon storage site requires a MMV plan that provides assurance regarding containment of the CO2 and conformance with regulations. Time-lapse seismic monitoring is the main technology for 3D localisation of the CO2, but associated costs are high. To address this, we consider an adaptive monitoring scheme that takes advantage of the modelling and risk identification conducted during the planning process. We consider two components of adaptive monitoring based on full-waveform modelling and inversion. The first is a data-domain CO2 detection and tracking technique that uses the subsurface model to map from subsurface zones of interest to shot gathers. The second is an adaptive 4D full-waveform inversion approach, where sparse 3D monitor surveys are designed to target specific subsurface changes using full-waveform inversion. Both approaches are enabled by a baseline model that honours the observed seismic wavefield. We illustrate these approaches using the SEG Advanced Modeling (SEAM) CO2 dataset. By combining different methods, the monitoring effort and frequency becomes adaptive, scaling with the evolution of the CO2 plume. This allows for a modular adaptive monitoring system, with each module addressing different monitoring objectives, from early warning to CO2 tracking, targeted model updates, and full 4D analysis and model updates.