The oil sands reservoirs in the Hangingstone area occur in the Lower Cretaceous McMurray formation and their distribution is very complex both vertically and horizontally. Steam chamber growth is strongly dependent on the reservoir facies changes around the SAGD injector/producer well pairs and the steam chambers usually spread irregularly through the reservoir zone. The understanding of the relationship between steam-affected zones and their reservoir geologies can help to plan further exploitation and production in the field.
The first survey was acquired in January, 2002 to construct a detailed 3D geological model for reservoir characterization and to optimize the deployment of the SAGD well pairs. The seismic data from the 2002 survey have seismic amplitude anomalies around the horizontal well pairs which were being used as steam-injection and production wells at that time. These amplitude anomalies were qualitatively interpreted as a result of acoustic impedance decrease of the reservoir sands caused by the steam-injection. The second survey was shot in March, 2006 to monitor the changes of the reservoir properties induced by the continuous steam injection process since the 2002 survey.
The data sets of both the baseline survey and the repeat survey were processed with similar processing flows and parameters at the same time. The differences between the two data sets in the reservoir zone were investigated while analyzing the synthetic seismic response and comparing with the reservoir facies changes predicted from the detailed 3D geological model that was constructed in 2002.
The time lapse seismic monitoring is expected to help better understand the heterogeneity of the reservoir sands by integrating the information of the steam chamber geometry and the seismic response analysis.