Monitoring of CO2 sequestration in ultrasonic laboratory

Potential of time-lapse crosswell tomography in monitoring CO2 underground storage is tested in a case of specific geological setting – thin coalbed seams. In contrast to tick reservoirs of sandstone aquifers, thin coal seams are difficult to image. In first European pilot project of CO2 injection in thin coal seams (RECOPOL) seismic monitoring was not successful. In laboratory, using ultrasonic measurements we investigate possible reasons and main problems. Furthermore, we test two different theories (ray and finite-frequency wave theory) underlying imaging method and their performance in monitoring of CO2 injection.