Seismic Detection and Characterization of a CO₂ Flood in Ardley Coals, Alberta, Canada

Michael Jason McCrank

At the Alder Flats pilot project, 180 tonnes of gaseous CO₂ was injected into the Ardley Coals at a depth of 0.4 km to test enhanced coalbed methane production, as well as carbon sequestration in coals. This thesis discusses the seismic monitoring program which was executed to image the CO₂ flood. Prior to commencement of CO₂ injection, two preliminary 2D surveys were conducted in order to assist in designing a third 3D survey which was acquired after CO₂ injection. Poststack inversion of the 3D vertical component data showed a low acoustic impedance anomaly up-dip and along strike of the preferential fluid pathway in the target coal zone. The size and location of the anomaly concurs with the expected imprint of the injected CO₂ and it has been interpreted as the CO₂ flood. The magnitude of the acoustic impedance anomaly suggests that a reduction in the elastic stiffness of the coal matrix frame may have been detected.