Interpretation of time-lapse seismic data from a heavy oil field, Alberta, Canada
Byron Matthew Kelly, Donald C. Lawton
Two 3-D seismic datasets and their difference volume were interpreted and analyzed for the presence of amplitude anomalies and time delays related to the injection of steam into a shallow, heavy oil reservoir. High amplitude anomalies were observed on the monitor data in conjunction with apparent time-thickening of the reservoir interval due to a decrease in the P-wave velocity. The decrease of velocity was interpreted to be due to the increase in reservoir temperature and decrease in differential pressure created from the injection of high temperature steam into the McMurray Formation reservoir. An analysis of the amplitude anomalies yielded a spatial display of reservoir steam chamber distributions.
The attenuation of high frequencies beneath steam chambers was observed within the monitor survey, characterized by low-frequency shadows, observable on the Devonian reflection underlying the amplitude anomalies.
Geological well log information was integrated with the geophysical observations. McMurray Formation channels sands were observed within the seismic data through the analysis of the semblance attribute, as well as within the geological data as low gamma ray values on well log cross sections. The channel sands were observed to intersect amplitude anomalies with the monitor volume. Outside of the amplitude anomalies, the channel sands were bound by muddy IHS bedding, creating baffles to steam flow.