Seismic Methods for Heavy Oil Reservoir Monitoring and Characterization

Zandong Sun

Extracted seismic attributes from time-lapse 3-D seismic data has been used extensively to map steam areal conformance by using statistical analysis in the development and monitoring of follow-up processes at Imperial Oil's Cold Lake production project.

In this dissertation, a quantitative cross-calibration scheme between time-lapse seismic surveys has been developed using data normalization. It was found that a significant difference results from using a different calibration set; and that time-lapse data crosscalibration provides better, more stable and consistent results.

Attributes from principal component decomposition of seismic data compensate for the redundancy of conventional seismic attributes in statistical analysis and provide better well-to-seismic ties when a full set of principal component attributes are used.

Vertical steam conformance can be established through post-stack inversion to provide 3D visualization of the impact of lithologic control on steam distribution and steam migration pathway. The vertical conformance reveals that sequence architecture has a significant influence on steam migration. A sequence with high mud content tends to limit or slow both vertical and lateral migration of the steam chambers.

Shear-wave information is useful for both reservoir characterization and monitoring fluid movement. Integrated surface 2-D seismic and borehole VSP P- and S-wave studies have illustrated that the task of differentiating lithology and identifying fluid can be achieved by integrating P- and S-wave information. However, when compared with P-P wave, the surface P-S wave lacks the resolution at Cold Lake area. 3-D 3-component VSP is the tool that will meet this need. A 3-D VSP survey design and processing stream have been developed in this dissertation.

The functional relation of P- to S-wave velocities, called the mud-rock line, plays an important rule in extracting S-wave information from pre-stack data. An optimized mudrock line for Cold Lake clastic rocks is an exponential relationship between P- and S-wave velocities. With an optimized mud-rock line and high frequency seismic data, the inverted psuedo S-wave from AVO analysis has much higher resolution than the P-S wave data. The reservoir heterogeneity can be well defined by fluid factor alone. The application of this technique to reservoir monitoring defines steam channels and identifies lithologic barriers within the reservoir.