Real-Time Multi-Well DAS Monitoring for Carbon Storage: Otway Stage 4 Implementation

Summary Seismic monitoring is a powerful method for ensuring conformance and assurance in geological carbon storage (GCS) projects, as it responds to changes in both saturation and pressure. When deployed in downhole configurations, it can also detect induced seismicity. The CO2CRC Otway Project, located onshore in Victoria, Australia, has served as a key research site for carbon capture and storage (CCS) technologies since 2007. In Stage 3, 15 kilotonnes (kt) of a supercritical CO2/CH4 mixture were injected into a reservoir at a depth of 1.5 km. Stage 4, which commenced in November 2024, involves the injection of an additional 20 kt of the same gas mixture into a formation approximately 50 metres above the previous interval. Continuous monitoring is a key focus of this phase. Both stages employ downhole distributed fibre optic sensing for seismic monitoring, supported by surface orbital vibrators (SOVs) for ongoing data acquisition and occasional 4D vertical seismic profiling (VSP) surveys. This presentation outlines the experimental setup and presents initial findings from the Otway Stage 4 injection program.