SPE Journal
Volume 17, Number 4, December 2012, pp. 1246-1254

Summary

Thermal stimulation of bitumen in oil-sands reservoirs is a critical requirement for the success of steam-based recovery processes such as steam-assisted gravity drainage (SAGD). If the bitumen is not heated, it remains at its original viscosity, often in the millions of centipoise and, thus, is not mobilized so that it cannot be moved to a production well. All oil-sands reservoirs are heterogeneous, both with respect to geology and fluid composition, and, thus, conformance of steam in the reservoir is not uniform. At present, real-time monitoring of the steam-conformance zone in the reservoir is not possible, and, thus, the spatial distribution of heat delivery to the reservoir is uncertain. In this research, a new method for detecting heterogeneity and monitoring steam chambers has been developed and tested by detailed thermal/acoustic reservoir simulation. Here, a thermal fluid-flow simulator was one-way coupled to a wave-propagation simulator (information passed is density alone) to evaluate the potential of identifying rock and fluid discontinuities during a SAGD operation with coded white-noise-reflection processes. Digital communication systems use coded white-noise processes to make advantageous use of unexpected reflections from environmental heterogeneities. The proposed theory and subsequent simulations reveal that it is possible to resolve the edge of the SAGD steam chamber and to image the heterogeneity within the reservoir as it evolves with white-noise-reflection methods. The properties of the signals described provide an opportunity for property detection at lower power levels and higher frequencies than traditional seismic methods. Furthermore, the signals are such that the noise from recovery processes and the native reservoir environment do not interfere with the detection methods, allowing for the monitoring method to be used concurrently with the recovery process.

© 2012. Society of Petroleum Engineers

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History

• Original manuscript received: 19 January 2011
• Meeting paper published: 19 October 2010
• Revised manuscript received: 22 March 2012
• Manuscript approved: 13 April 2012
• Published online: 27 November 2012
• Version of record: 6 December 2012