Section 1: Rock Physics Aspects
Published:January 01, 2010
With a high demand of hydrocarbon worldwide, conventional oil production is quickly approaching its peak. Inevitably, heavy oil and bitumen (ultraheavy oil) will emerge as “new” (so-called unconventional) hydrocarbon resources because of their tremendous potential. Currently, more than 50% of Canada’s oil production is from heavy oils (Alboudwarej et al., 2006; Hinkle and Batzle, 2006).
Such heavy oils are highly viscous, difficult to move in reservoirs, and much more expensive to produce. In addition to mining and other cold production methods, many different techniques (e.g., thermal, chemical, or in situ combustion, etc.) have been applied to mainly reduce viscosity and assist the heavy-oil production. None of these techniques have matured completely yet, and engineering developments are occurring rapidly. These techniques remain expensive in terms of energy and resources used (lots of water) and in terms of efficiency and overall environmental impact. The steam-assisted gravity drainage (SAGD) technique is a current popular technique. In a steam chamber, more than 60% of oil in place can be produced (Caruso, 2005; Gupta, 2005). However, on a reservoir scale, efficiency can be low (approximately 15% with different resources). Clearly, seismic techniques hold great potential for assisting reservoir characterization and recovery monitoring. Monitoring has been demonstrated successfully in several fields [Cold Lake (Eastwood et al., 1994) and Duri Field, Indonesia (Jenkins et al., 1997)]. However, to be effective, we must understand the seismic properties of the heavy oils and the heavy-oil sands. This understanding of in situ properties is the key to bridging the seismic response to reservoir properties and changes. Schmitt (2004) provided a general review of rock physics as related to heavy-oil reservoirs. Here, we examine the seismic properties of heavy oils in detail.
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Heavy Oils: Reservoir Characterization and Production Monitoring
Heavy oil is an important global resource with reserves comparable to those of conventional oil. As conventional resources get thinner, attention is being focused on heavy oil and bitumen, which hold the promise of becoming useful fuels. Already more than 1 million barrels of oil are being produced from the oil sands in Canada; heavy oil represents half of California’s crude oil production in the United States and is a major production in Mexico. With demand for global energy soaring, heavy oil will undoubtedly be an important resource to be exploited in a big way in the near future.
The SEG Development and Production Committee held its Heavy Oil Forum in Edmonton, Alberta, in July 2007. This was a joint research forum cosponsored by the Canadian Society of Exploration Geophysicists (CSEG) and SEG and hosted by the University of Alberta. Preceding the forum, a field trip took the participants to the vast Athabasca Oil Sands region where they observed the outcrops, open pit mining, and steam injection operations, followed by a tour of the steam-assisted gravity drainage projects. Topics of the well-attended forum included the definition of heavy oil; where is heavy oil found; how it is produced; heavy-oil reservoir characterization; fluid and rock properties; electrical, tilt, and gravity techniques; borehole, surface seismic measurements; and microseismicity.